SOFTWOOD GASIFICATION IN A SMALL SCALE DOWNDRAFT GASIFIER
HUMBOLDT STATE UNIVERSITY
By
Michael Joseph Purdon
A Thesis
Presented to
The Faculty of The Department of Environmental Resources Engineering
In Partial Fulfillment
Of the Requirements for the Degree
Master of Science
In Environmental Systems:
Environmental Resources Engineering Option
August, 2010
SOFTWOOD GASIFICATION IN A SMALL SCALE DOWNDRAFT GASIFIER
By
Michael Joseph Purdon
Approved by the Master's Thesis Committee:
Dr. Arne Jacobson, Major Professor Date
Dr. Charles Chamberlin, Committee Member Date
Dr. Christopher Dugaw, Graduate Coordinator Date
Dr. Jená Burges, Vice Provost Date
ABSTRACT
SOFTWOOD GASIFICATION IN A SMALL SCALE DOWNDRAFT GASIFIER
Michael Joseph Purdon
This thesis is a performance evaluation of a small scale, 11 kilowatt electric, kWe, downdraft gasifier made by Ankur Scientific. According to the US Department of
Energy, the potential exists to displace 30% of the United States’ petroleum use by gasifying sustainably harvested biomass which includes forest residues and biomass from forest thinning operations. Transportation costs for this biomass is high, however. One way to minimize these costs is to use small scale, decentralized gasifiers near the harvest sites. Furthermore, the preferred type of gasifier for the small scale is the downdraft gasifier type. A majority of US forests are softwood, and most of the forest derived biomass resource that would be used for gasification is softwood. Historically, however, hardwood has been the preferred fuel for downdraft gasifiers. Therefore, the need exists to evaluate the efficacy of using softwood fuel for downdraft gasification. The softwood fuel used in this evaluation was Douglas Fir wood chips. Moisture content, MC, of the fuel is critical to performance, so in this study, the MC of the fuel was varied from 6% to
22%. The survey consisted of three experiments at 6% MC, four at 13% MC, and three at 22% MC. The experimental run times were relatively short; they averaged 2.9 hrs per experiment. The cold gas efficiency of the gasifier was reasonably stable across the three
MCs, with an average of 65.7%. Most performance parameters matched those in the literature for various hardwood studies, but the amount of hydrogen produced was lower
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than all reported values in the literature. The filtration system produced hazardous waste from the sawdust and bag filters. Also, a number of maintenance issues were encountered during the survey which included initial carbon monoxide leaks and mechanical failure of various components of the gasifier. This study showed that softwood gasification is possible, and performance is comparable to hardwood fuel.
However, the short run times and maintenance issues encountered reveal that much more research and development are needed if decentralized gasification is to become a feasible option for converting the potential stock of sustainably harvestable US biomass into energy.
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ACKNOWLEDGEMENTS
First, if it weren’t for funding, no research would be conducted anywhere. I would like to thank the Indonesian Sugar Group for sponsoring this research, which provided the Schatz Energy Research Center with their first gasifier and gas chromatograph. The work was carried out through a collaboration with a team from the
Renewable and Appropriate Energy Laboratory (RAEL) at UC Berkeley, led by Dr.
Daniel Kammen. This is the first experimental thesis conducted on this gasifier; may many more theses be conducted in the future with it. Based on my results, there’s a lot of work left to do.
Second, if it weren’t for the amazing and diverse staff at SERC, this work would have never been completed. Project manager Greg Chapman helped run the experiments and installed all of the tubing and fittings for both the gasifier and the gas chromatograph, among many other things. He also watched over me and made sure I didn’t kill myself from the 200,000 ppm of carbon monoxide in the gasifier’s product gas. Marc Marshall and Scott Rommel handled all of the electronic connections and instrumentation, including writing the Labview program to handle the bulk of the data collection. Mark
Rocheleau and Ray Glover fabricated all of the custom parts needed to keep the gasifier safe and running, which even included a steel reinforced broom that I used to push the woodchips around when I was drying them. James Apple was a great asset as he helped me perform the experiments, dry the woodchips, and analyze the data. Ranjit Deshmukh was key in the purchase of the gasifier from India, which came complete with wood
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eating beetles in the crates. I’m really glad they didn’t survive the climate and eat the
Redwood Forest.
Third, I would like to thank Tom Miles for his comments and insights on the results of this study. Tom is a leading expert on the subject of small scale downdraft gasification, and his comments made the results much more clear.
Finally, I’d like to thank Arne Jacobson and Charles Chamberlin for their assistance throughout the thesis process. Charles didn’t let anything slip through the cracks, and was always there for a good heated argument when discussing the results.
Arne has been there for me the entire time, even responding to frantic emails at midnight.
If it weren’t for Arne, I never would have finished. I thank Arne most for helping me only after I helped myself. In all of my years in academia, I’ve never had a teacher as compassionate and caring as Arne. Humboldt State is a much better place with him on their team. Thank you for everything.
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TABLE OF CONTENTS
ABSTRACT...... iii
ACKNOWLEDGEMENTS...... v
LIST OF TABLES...... x
LIST OF FIGURES ...... xv
CHAPTER 1. INTRODUCTION...... 1
CHAPTER 2. REVIEW OF LITERATURE...... 3
Gasification- A Brief History ...... 6
The Gasification Process ...... 7
The Gasification Process - Critical Variables...... 11
The Gasification Process – Performance Indicators...... 13
CHAPTER 3. METHODS AND OPERATION...... 22
Variables ...... 22
Experimental Setup – Gasifier Operation...... 23
Experimental Setup – Gasifier Instrumentation...... 30
Methods – Fuel Preparation and Data Collection...... 37
Methods – Calculating the Cold Gas Efficiency ...... 42
Methods – Performance Evaluation...... 47
CHAPTER 4: RESULTS...... 49
Efficiency Interval and Its Determination ...... 50
Equivalence Ratio...... 51
vii
TABLE OF CONTENTS (continued)
Gas Composition...... 52
Energy Content ...... 58
Cold Gas Efficiency...... 59
Tars and Particulates...... 61
Fuel Consumption...... 63
Thermal Output Power...... 64
Char-Ash...... 65
Gasifier Maintenance...... 66
CHAPTER 5. DISCUSSION...... 73
Experimental Run Time...... 73
Equivalence Ratio...... 75
Gas Composition...... 75
Energy Content of Product Gas...... 77
Fuel Consumption Rate ...... 78
Cold Gas Efficiency...... 79
Thermal Power...... 81
Tars and Particulates...... 81
Douglas Fir Woodchips as Fuel...... 82
Performance Evaluation...... 84
viii
TABLE OF CONTENTS (continued)
CHAPTER 6. CONCLUSIONS AND RECOMMENDATIONS...... 88
REFERENCES ...... 92
APPENDIX A...... 95
A.1 Run Summary for 5.7% Moisture Content Run...... 95
A.2 Run Summary for 5.8% Moisture Content Run...... 98
A.3 Run Summary for 5.5% Moisture Content Run...... 101
A.4 Run Summary for 13.4% Moisture Content Run...... 104
A.5 Run Summary for 12.2% Moisture Content Run...... 107
A.6 Run Summary for 12.8% Moisture Content Run...... 110
A.7 Run Summary for 12.5% Moisture Content Run...... 113
A.8 Run Summary for 22.6% Moisture Content Run...... 116
A.9 Run Summary for 21.6% Moisture Content Run...... 119
A.10 Run Summary for 21.5% Moisture Content Run...... 122
APPENDIX B...... 125
B.1 Orifice Plate Flow Meter Calibration...... 125
B.2 Sample Line Flow Meter Calibration...... 127
APPENDIX C...... 129
C.1 Estimating Product Gas Temperature Profile for First Two 13% MC Runs...... 129
ix
LIST OF TABLES
Table Page
2.1: Principal chemical reactions in gasification (Kaupp & Goss, 1984)...... 8
2.2: Typical gas compositions from biomass fuel in downdraft gasifiers...... 15
2.3: Typical energy contents of product gas in downdraft gasifiers...... 17
2.4: Cold gas efficiencies for biomass in downdraft gasifiers...... 19
3.1: Ankur WBG20 specifications from Operations Manual, (Ankur Scientific 2008). . 23
3.2: Thermocouples used on gasifier...... 32
3.3: Pressure transducers and manometers on gasifier...... 33
3.4: Scott Specialty Gases calibration gas composition and Ankur’s expected gas composition...... 36
3.5: Gas properties (Sonntag et al., 2003)...... 45
4.1: Time of efficiency intervals for each experiment...... 51
4.2: Equivalence ratio for each experiment...... 52
4.3: Complete average product gas composition, %, and standard deviation for 10 experimental gasifier runs using Douglas Fir woodchips as fuel...... 57
4.4: Average energy content of product gas for 10 experimental gasifier runs using Douglas Fir woodchips as fuel...... 59
4.5: Energy content of oven dry Douglas Fir woodchips...... 60
4.6: Cold gas efficiency for each experiment...... 61
4.7: Tars and particulate matter in product gas for each experiment...... 62
4.8: Average tar and particulate matter for each experiment, and for each set of moisture content experiments...... 63
x
LIST OF TABLES (continued)
4.9: Dry fuel consumption rate for each experiment during efficiency interval...... 64
4.10: Char-ash percentages for each set of MC experiments...... 66
4.11: Energy content of char-ash generated in Ankur gasifier...... 66
5.1: Average product gas composition of each set of MC experiments compared with manufacturer’s claims...... 76
5.2: Average dry fuel consumption compared to manufacturer’s claim (kg/hr)...... 79
A.1.1 Cold gas efficiency determination for 5.7% MC run during efficiency interval. .. 95
A.1.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 5.7% MC Run...... 95
A.1.3 Tar and particulate measurements for 5.7% MC run...... 95
A.1.4 Processed data for each GC interval for 5.7% MC run...... 96
A.1.5 Unprocessed GC gas composition for 5.7% MC run (mole percent)...... 97
A.2.1 Cold gas efficiency determination for 5.8% MC run during efficiency interval. . 98
A.2.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 5.8% MC run...... 98
A.2.3 Tar and particulate measurements for 5.8% MC run...... 98
A.2.4 Processed data for each GC interval for 5.8% MC run...... 99
A.2.5 Unprocessed GC gas composition for 5.8% MC run (mole percent)...... 100
A.3.1 Cold gas efficiency determination for 5.5% MC run during efficiency interval.101
A.3.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 5.5% MC run...... 101
A.3.3 Tar and particulate measurements for 5.5% MC run...... 101
xi
LIST OF TABLES (continued)
A.3.4 Processed data for each GC interval for 5.5% MC run...... 102
A.3.5 Unprocessed GC gas composition for 5.5% MC run (mole percent)...... 103
A.4.1 Cold gas efficiency determination for 13.4% MC run during efficiency interval ...... 104
A.4.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 13.4% MC run...... 104
A.4.3 Tar and particulate measurements for 13.4% MC run...... 104
A.4.4 Processed data for each GC interval for 13.4% MC run...... 105
A.4.5 Unprocessed GC gas composition for 13.4% MC run (mole percent)...... 106
A.5.1 Cold gas efficiency determination for 12.2% MC run during efficiency interval.
...... 107
A.5.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 12.2% MC run...... 107
A.5.3 Tar and particulate measurements for 12.2% MC run...... 107
A.5.4 Processed data for each GC interval for 12.2% MC run...... 108
A.5.5 Unprocessed GC gas composition for 12.2% MC run (mole percent)...... 109
A.6.1 Cold gas efficiency determination for 12.8% MC run during efficiency interval.
...... 110
A.6.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 12.8% MC run...... 110
A.6.3 Tar and particulate measurements for 12.8% MC run...... 110
A.6.4 Processed data for each GC interval for 12.8% MC run...... 111
xii
LIST OF TABLES (continued)
A.6.5 Unprocessed GC gas composition for 12.8% MC run (mole percent)...... 112
A.7.1 Cold gas efficiency determination for 12.5% MC run during efficiency interval.
...... 113
A.7.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 12.5% MC run...... 113
A.7.3 Tar and particulate measurements for 12.5% MC run...... 113
A.7.4 Processed data for each GC interval for 12.5% MC run...... 114
A.7.5 Unprocessed GC gas composition for 12.5% MC run (mole percent)...... 115
A.8.1 Cold gas efficiency determination for 22.6% MC run during efficiency interval.
...... 116
A.8.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 22.6% MC run...... 116
A.8.3 Tar and particulate measurements for 22.6% MC run...... 116
A.8.4 Processed data for each GC interval for 22.6% MC run...... 117
A.8.5 Unprocessed GC gas composition for 22.6% MC run (mole percent)...... 118
A.9.1 Cold gas efficiency determination for 21.6% MC run during efficiency interval.
...... 119
A.9.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 21.6% MC run...... 119
A.9.3 Tar and particulate measurements for 21.6% MC run...... 119
A.9.4 Processed data for each GC interval for 21.6% MC run...... 120
xiii
LIST OF TABLES (continued)
A.9.5 Unprocessed GC gas composition for 21.6% MC run (mole percent)...... 121
A.10.1 Cold gas efficiency determination for 21.5% MC run during efficiency interval.
...... 122
A.10.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 21.5% MC run...... 122
A.10.3 Tar and particulate measurements for 21.5% MC run...... 122
A.10.4 Processed data for each GC interval for 21.5% MC run...... 123
A.10.5 Unprocessed GC gas composition for 21.5% MC run (mole percent)...... 124
B.1: Orifice plate voltages, mass flow readings, and predicted mass flow readings..... 126
B.2: Sample line mass flow meter parameters for correction factor determination...... 128
C.1: Estimated product gas temperature profile for the first two 13% MC experiments, using a polynomial fit to the product gas temperature profiles of the final two 13% MC experiments...... 131
xiv
LIST OF FIGURES
Figure Page
2.1: Large volume cost comparison of energy resources in Wisconsin (Bergman & Zerbe 2004) ...... 5
2.2: Preferred gasification technologies vs. scale (Larson, 1998) ...... 5
2.3: Diagram of the hopper-reactor system in a downdraft gasifier, showing the different zones of the gasification process (Reed & Das, 1988)...... 9
2.4: Equilibrium gas composition as a function of equivalence ratio (Reed & Das, 1988)...... 14
2.5: Gas composition as a function of moisture content using cottonwood as fuel (Chee, 1987)...... 16
2.6: Energy content of product gas as a function of moisture content using cottonwood as a fuel source (Chee 1987)...... 18
2.7: Gasification efficiency as a function of moisture content (Ptasinski et al., 2006). .. 19
2.8: Cold gas efficiency as a function of moisture content using cottonwood as a fuel source (Chee 1987)...... 20
3.1: Ankur WBG20 downdraft gasifier installed at Schatz Energy Research Center. The fuel feed door, fuel hopper, reactor, filtration system, and water scrubber system are shown...... 24
3.2: Process diagram of Ankur gasifier as installed...... 25
3.3: Water scrubber system showing water pump, water jet system, and the four baffled barrels that both store the water and allow particulate matter to settle...... 28
3.4: Filtration system showing the sawdust filter and bag filter. The sample port is also shown...... 29
3.5: Schematic of gasifier setup and instrumentation...... 31
xv
LIST OF FIGURES (continued)
3.6: Sample line filtration system for cleaning the product gas prior to analysis with the gas chromatograph...... 35
3.7: Sieved Douglas Fir wood chips...... 38
4.1: Equivalence ratio vs. moisture content of fuel...... 52
4.2: Average product gas composition vs. moisture content of fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel...... 54
4.3: Average product gas nitrogen content vs. moisture content of fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel...... 54
4.4: Average product gas carbon monoxide content vs. moisture content of fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel...... 55
4.5: Average product gas hydrogen content vs. moisture content of fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel...... 55
4.6: Average product gas carbon dioxide content vs. moisture content of fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel...... 56
4.7: Average product gas methane content vs. moisture content of fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel...... 56
4.8: Average energy content of product gas vs. moisture content of fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel...... 58
4.9: Cold gas efficiency vs. moisture content of input fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel...... 60
4.10: Tars and particulates in product gas vs. moisture content of input fuel for n = 26 determinations...... 62
4.11: Dry fuel consumption rate vs. moisture content of fuel...... 63
4.12: Thermal output power vs. efficiency interval run time for each experiment...... 65
4.13: Vibrator motor and broken mounts...... 67
xvi
LIST OF FIGURES (continued)
4.14: Looking straight up into the bottom of the reactor bed, this image shows that the ash gets clogged before it drops into the automatic ash collection system, which has been moved to the side for manual removal of the ash...... 69
4.15: Tar and particulate buildup around and behind water jet in scrubber system...... 70
4.16: The water jet, pictured above, is installed here in the scrubber system, where more tar and particulate buildup is visible...... 70
5.1: Unprocessed product gas mass flow readings for the 21.6% MC experiment, the second in the 22% MC set...... 74
5.2: Product gas energy content vs. carbon monoxide content...... 78
5.3: Product gas energy content vs. dry fuel consumption rate...... 80
5.4: Average cold gas efficiency vs. char-ash production...... 81
C.1: Product gas temperature profiles for 10 experimental gasifier runs using Douglas Fir woodchips as fuel...... 129
C.2: Polynomial fit of the product gas temperature profiles of the 3 rd and 4 th 13% MC experiments...... 130
xvii
CHAPTER 1. INTRODUCTION
This thesis is a performance evaluation of an Ankur WBG20 small scale downdraft gasifier, manufactured by Ankur Scientific. The gasifier was tested using
Douglas Fir, a softwood, as a fuel source. Since moisture content of the fuel is critical to performance, this evaluation consisted of operating the gasifier in a series of experiments where the moisture content of the fuel was varied. According to the Department of
Energy, the potential exists in the United States to generate enough electricity, by gasifying biomass, to displace 30% of the United States’ current petroleum use. For this purpose, part of the available stock of biomass could at least theoretically come from sustainable harvesting of forests (Perlack et. al., 2005). A majority of this biomass is softwood, but historically, downdraft gasifiers have used hardwood as a fuel source
(Adams et. al., 2006, Reed & Das, 1988). Therefore, a need exists to quantify the performance of softwood fuel in small scale downdraft gasifiers.
In chapter two, projections for the role gasification can play in future energy generation are presented, which provides the rationale for the study. Also, a brief history of gasification and the gasification process itself are presented. Finally, the various performance parameters that were studied are discussed, and typical values from the literature for each parameter are presented.
In chapter three, the methods used to conduct the study are presented. A description of the gasifier is given along with the critical variables that affect its performance. A summary of both the operation of the gasifier and all installed
1 2 instrumentation is included. Also, a description is given of each performance parameter that was measured, along with the respective data collection procedures. Finally, the derivation of the equation used to determine the efficiency of this particular gasifier is presented.
In chapter four, the results of the study are presented. The results for each performance parameter are presented in graphical as well as in tabular form. Also, while running the series of experiments, a number of maintenance issues were encountered. In this chapter, a summary of these issues is presented along with the steps taken to resolve each issue.
In chapters five and six, discussions and conclusions are presented. Each result is discussed and the data collected in this study are compared to data found in the literature and to Ankur’s own claims. Comments on the difference between hardwood and softwood, and the difficulty of gasifying softwood, are presented. Also, the performance evaluation of the Ankur WBG20 gasifier is presented. Finally, the conclusion summarizes the findings of this thesis and outlines recommendations for future work in downdraft gasification as it pertains to energy generation from forest derived biomass, particularly in the western United States.
CHAPTER 2. REVIEW OF LITERATURE
In the current search for alternative energy sources, gasification is one option
among many. Gasification converts carbon based solid fuel to combustible gaseous fuel.
An excess of oxygen exists during complete combustion, but during gasification, an
excess of carbon exists. The gasification process is therefore said to be oxygen starved
(Kaupp & Goss, 1984). The combustible gas can be directly used to generate heat or can
fuel an internal combustion engine or gas turbine to generate mechanical power or
electricity.
Interest in gasification is on the rise because it represents an attractive way to
utilize the planet’s vast biomass resource for energy generation. The attractiveness is
two-fold. First, biomass can be a carbon neutral fuel because as new biomass grows and
replaces what was taken, the CO 2 is re-absorbed. Second, the gasification process can be more efficient than direct combustion.
Biomass is abundant, and is already the largest renewable energy resource used in the US (Perlack et al., 2005). A feasibility study, conducted by the US Department of
Energy and the US Department of Agriculture, determined if it was possible to displace
30% of current US petroleum use by using domestic biomass. This study estimated that
1366 million oven dry tons per year, bdt/yr, can be sustainably harvested in the US to meet this goal. Of this total, an estimated 368 million bdt/yr would theoretically come from US forestlands. In 2003, 190 million bdt/yr of forest derived biomass was actually used in the US for energy generation, so the potential exists to nearly double the amount
3 4 currently utilized (Perlack et al., 2005). This thesis will focus on the forest derived biomass portion of the available stock.
Biomass energy has the potential to be economical. Bergman and Zerbe (2004) show that wood chips in particular are a relatively cheap energy source, Figure 2.1. Also, the Western Governors’ Association’s Clean and Diversified Energy Advisory
Committee commissioned a task force to study the potential of economical biomass power by 2015. The task force reported that 10,000MW of power can be produced from biomass at 8¢/kWh by 2015. Various gasification technologies, which are not currently operating, are a significant part of the power generation technologies of this assessment
(Gray et al., 2006).
Although these projections appear positive, one critical factor may severely inhibit the large scale use of this potential resource: transportation costs. The potential stock of biomass includes forest residues left behind after a timber harvest as well as biomass from forest thinning operations. Rural transportation costs are in the range of
$0.25 – $0.27/ton-mile (Demeter et al., 2003). Perlack et al. (2005) give a larger range of
$0.20 - $0.60 / ton-mile. Such high transportation costs will spur locating the power generation capacity close to the harvest site.
5
Figure 2.1: Large volume cost comparison of energy resources in Wisconsin (Bergman & Zerbe 2004)
One method to reduce the high transportation cost of biomass is to utilize decentralized, small scale, power generation systems near timber harvest sites and forest thinning sites. The use of small scale decentralized gasifiers as the power generation systems therefore represents one option to minimize costs. For systems smaller than 1
MW fuel capacity, the downdraft gasifier type is the only feasible gasification technology, Figure 2.2 (Larson, 1998). Therefore, this thesis focuses on an evaluation of the performance of a small scale downdraft gasifier.
Figure 2.2: Preferred gasification technologies vs. scale (Larson, 1998)
6 Historically, small scale downdraft biomass gasifiers used “highly processed,
hardwood blocks” as a fuel source (Reed & Das, 1988). A significant portion of the
available biomass resource for US power generation is softwood, however. In 2002, the
total US supply of harvested forest derived biomass was 60% softwood. Furthermore, in
2002, the total harvested forest derived biomass from California, Oregon, and
Washington was 83.5% softwood (Adams et al., 2006). Softwood will undoubtedly be a
major fuel source if gasifiers are to be widely used, especially in the western states. For
these reasons, softwood fuel will be used in this thesis for the performance evaluation of
the Ankur WBG20 small scale downdraft gasifier.
Gasification- A Brief History
Gasification technology has existed for over 200 years. The first patent related to gasification was issued in 1788, and the first commercially used gas producer was commissioned in 1840 for the iron works of Audincourt, France (Kaupp & Goss, 1984).
By 1850, manufactured gas from coal was used extensively in London for lighting. This technology migrated to the US during this time and by 1920, a majority of American towns and cities had gasification facilities that supplied residents with gas for cooking and lighting. However, the production of manufactured gas, or town gas, quickly declined in the 1930’s as it was displaced by natural gas (Reed & Das, 1988).
Although town gas became virtually obsolete by 1940, small scale gasifiers for transportation purposes increased rapidly in Europe during World War II. By the end of
7 the war, there were approximately 1 million cars and trucks in Europe that were powered by gasifiers, fueled by processed coal or hardwood (Reed & Das, 1988).
The rapid implementation of syngas powered vehicles during this time was due to the war. Oil and natural gas were in short supply and the military was given priority over civilians, who were left without. After the war, in the 1950’s and 1960’s, the technology vanished, along with the knowledge and wisdom of the experienced operators, as inexpensive and abundant supplies of oil and natural gas rendered the technology obsolete. Tom Reed and Agua Das (1988), and Ali Kaupp and John Goss (1984), have summarized the experience contained in over 1000 pre-1950 documents and papers written on gasification in order to help the next generation of scientists and engineers as the technology becomes popular once again, this time for its renewable energy potential.
The Gasification Process
Gasification is the thermal breakdown of organic matter into combustible gases in an oxygen starved environment. The main combustible gases are hydrogen and carbon monoxide, but small amounts of methane, ethane, ethene, and acetylene are also produced. It is generally accepted that five primary endothermic and exothermic chemical reactions drive the process, Table 2.1 (Kaupp & Goss, 1984). These reactions do not reach equilibrium and a single general net reaction equation thus cannot be determined. Overall gasification efficiency is generally reported empirically and is dependent on the specific gasifier used, fuel type, fuel moisture content, and fuel geometry.
8 Table 2.1: Principal chemical reactions in gasification (Kaupp & Goss, 1984). Reaction Chemical Formula Combustion C + O 2 = CO 2 + 393,800 kJ/kg mole Water Gas C + H 2O = CO + H 2 – 131,400 kJ/kg mole Water Shift Reaction CO + H 2O = CO 2 + H 2 + 41,200 kJ/kg mole Boudouard Reaction C + CO 2 = 2CO – 172,600 kJ/kg mole Methane Reaction C + 2H 2 = CH 4 + 75,000 kJ/kg mole
Figure 2.3 illustrates a typical downdraft gasifier design that is representative of the gasifier used in this thesis. The top of the hopper is sealed when fuel is not being loaded, and air enters at the bottom of the hopper, which is the top of the reactor, through air inlets. There is not a clear boundary between the hopper and reactor because as the fuel travels down through the hopper, chemical reactions occur as the fuel gets heated.
The product gas exits the reactor at the bottom, and travels to an exit pipe. The gasifier is double walled so the exiting gas is kept separate from the fuel inside the reactor, between the inner and outer walls of the gasifier. The double walled feature also insulates the gasifier.
9
Figure 2.3: Diagram of the hopper-reactor system in a downdraft gasifier, showing the different zones of the gasification process (Reed & Das, 1988).
The top of the hopper serves as storage for the fuel. As the fuel travels down, its temperature increases as it approaches the combustion zone. All incoming oxygen via the air inlets is consumed in the combustion zone, so the hopper and reactor are virtually oxygen free everywhere else. The excess fuel that is not combusted therefore begins to undergo pyrolysis, the thermal breakdown of matter in the absence of oxygen. In the case of biomass, the matter degrades into oils, tars, and gases. Since there isn’t enough oxygen available to burn all of the biomass, as the fuel reaches the air inlet portion of the hopper, most of it isn’t burned, but instead experiences flaming pyrolysis, converting the fuel into tars and combustible gases (Reed & Das, 1988, Kaupp & Goss, 1984).
10 The main advantage of the downdraft gasifier, versus updraft for example, is its
low tar product gas. Woodchips are 80% volatile matter and therefore, during pyrolysis,
over 200 various molecules are formed which are defined as tar (Milne et al., 1998). In
the downdraft design, all gas must pass through a small throat at the bottom of the
combustion/flaming pyrolysis zone. Because this zone is in the range of 1100 – 1600 ºC,
these tars are cracked as they pass through the throat, leaving only 1% of the initial tars.
The stable gases that remain in this hot zone are mostly N 2, H 2, H 2O, CO, CO 2, and CH 4.
This is not the case for an updraft gasifier, for example, because the air is moving up through the fuel, and the tars formed during pyrolysis leave with the product gas without passing though a hot combustion zone throat (Reed & Das, 1988).
Immediately following the combustion/flaming pyrolysis zone is the reduction zone. Here, the remaining solid matter is in the form of hot charcoal, or char, and all product gas comes into contact with it. The two main endothermic reactions take place here, the Water Gas and Boudouard reactions. In these reactions, H 2O and CO 2 react
with carbon in the char, and are cracked into more H 2 and CO. These reactions essentially dissolve the charcoal by consuming the carbon (Reed & Das, 1988).
The charcoal decreases in size due to the reduction reactions, and in the Ankur gasifier used in this thesis, the small particles and fine powder are swept out of the bottom of the gasifier through a grate. Some carbon still remains in the ash, so it is called char-ash. The char-ash falls down, and the product gas passes through the grate and is drawn out of the gasifier into the filtration system. A blower at the end of the filtration
11 system is the mechanism that forces the air into the nozzles, and forces the gas through the gasifier (Reed & Das 1988).
The downdraft gasifier has self correcting properties that make it attractive. First, the combustion zone is maintained at a consistent level within the reactor. If there isn’t enough charcoal in the combustion zone, then more fuel is burned and pyrolyzed to make more charcoal. Conversely, if there is too much charcoal, the incoming air burns it down to the correct level. Also, the reduction reactions help prevent overheating. As the temperature increases, these reaction rates increase rapidly. Because they are endothermic, energy is consumed during the reactions, and the gas cools (Reed & Das,
1988).
The Gasification Process - Critical Variables
The first critical variable in gasification is the fuel type. A wide range of fuel types exist from coal to wood to agricultural byproducts. Each fuel type has a different shape, size, chemical makeup, moisture content, and ash content. These properties affect how the fuel physically moves through the gasifier as well as its ability to be gasified.
Generally, if a gasifier is designed to handle one type of fuel, it will perform poorly when different fuels are used (Kaupp & Goss, 1984). The gasifier used in this thesis is designed to use woodchips as a fuel source, although different hoppers can be fitted to it in order to handle other fuels such as rice hulls.
The second critical variable in gasification is fuel size. The size of the fuel affects how it flows through the gasifier, which affects steady state gas production. If a fuel’s
12 bulk density is too high, then incoming air from the inlets cannot penetrate far enough into the fuel bed in the hopper. If the bulk density is too low, then too much air enters which leads to too much combustion, and too little combustible gas production. Also, if the bulk density is not constant, then the airflow distribution inside the hopper is transient, which leads to transient gas production. It is best for the fuel to be of uniform particle size (Reed & Das, 1988). The woodchips used in this thesis will have an upper limit on particle size, but will have a non-uniform distribution.
The moisture content of the fuel is the third critical variable. There are two methods used to quantify the fuel moisture content, wet basis and dry basis. Each method requires drying the fuel to first determine the mass difference between the wet and dry fuel. For the wet basis, the moisture content is the percentage of moisture in the fuel relative to the original mass of wet fuel, and is therefore always less than 100%. For the dry basis, the moisture content is the percentage of moisture in the fuel relative to the mass of the dry fuel, and can be greater than 100%. The general rule for downdraft gasification is that the fuel moisture content needs to be 20% or less, on a wet basis. In other words, 20% or less of the mass of the fuel being loaded into the gasifier can be water. Energy is lost in vaporizing water, which decreases the overall efficiency of the gasification process if the fuel is too wet. If the fuel is too dry, then hydrogen production via the water shift reaction may be limited. Finding the balance between fuel type, size distribution, and moisture content is therefore the small scale downdraft gasifier operator’s greatest challenge (Reed & Das, 1988).
13 The Gasification Process – Performance Indicators
The equivalence ratio is the first metric used to evaluate gasifier performance. It is the mass ratio between the actual air-fuel ratio and the air-fuel ratio required for complete stoichiometric combustion, a ratio of ratios. In gasifiers, this ratio is always less than one because gasification requires less air than is needed for complete combustion. Although the various forms of biomass differ in composition, the distribution of carbon, oxygen, and hydrogen are similar, so a general biomass formula can be used, CH 1.4 O0.6 (Reed 1979). The formula for complete stoichiometric combustion of biomass is given, Equation 2.1.
CH 4.1 O 6.0 + 05.1 O2 + 05.1 78.3( N 2 ) → CO 2 + 7.0 H 2O + 05.1 78.3( N 2 ) 2.1
Therefore, on a mass basis, it takes 144.78 g of air to completely combust 23.02 g of biomass. The air-fuel ratio for complete stoichiometric combustion of biomass is thus
6.29 on a mass basis (Reed 1979). Knowing this, the equivalence ratio can be determined for a gasifier by measuring the amount of air entering the inlets and weighing the amount of oven dry fuel consumed. The presence of nitrogen in the product gas can be used as a tracer to back calculate the original amount of air that entered the gasifier. If the five principal gasification chemical reactions are allowed to proceed to equilibrium, the product gas composition can be determined by the equivalence ratio, Figure 2.4.
Although the reactions rarely reach equilibrium, this figure illustrates the gas composition trends as the equivalence ratio approaches one for complete combustion. At complete
14
combustion, the only remaining products are the combustion products CO 2 and H 20. The
optimal equivalence ratio is theoretically 0.25, where the mole fraction of CO peaks and
the product gas energy content is maximized (Reed & Das 1988). Zainal (2002)
experimentally investigated the effect of the equivalence ratio on the performance of a 50
kW downdraft gasifier, and found 0.38 to be the optimal equivalence ratio for that
particular gasifier. Sheth (2009) reports 0.205 as an optimal equivalence ratio for their
bench scale downdraft gasifier.
Figure 2.4: Equilibrium gas composition as a function of equivalence ratio (Reed & Das, 1988).
Gas composition is the second metric used for evaluating gasifier performance.
The gasifier design, as well as the physical and chemical properties of the fuel itself, affects the gas composition. As seen above, the amount of air entering the gasifier also
15 affects gas composition, as too much air leads to too much combustion. Various gas
compositions are given for woody biomass in downdraft gasfiers, Table 2.2.
Table 2.2: Typical gas compositions from biomass fuel in downdraft gasifiers.
Fuel
Chipped Untreated General Wood Wood Tree Cottenwood Wood Biomass Chips Prunings (theoretical)
Moisture Content, wet basis
12 – 20 % 17.3% 15.7% 19.8% < 20%
Percent Composition of Product Gas
CO 21.0 17-22 18.8 21.0 17.7 16 - 22 CO 2 9.7 10-15 13.7 13.6 12.6 7 - 13 H2 14.5 16-20 16.4 17.3 22.7 16-20 CH 4 1.6 2-3 4.75 2.1 1.3 < 3 N2 48.4 55-60 46.1 45.2 38 50 C2H6 0.25 0.1 Reed & Ankur Rajvanshi Kaupp & Ptasinski et Das Chee (1987) Scientific Source (1986) Goss (1984) al. (2006) (1988) (2008)
The moisture content of the fuel also affects the gas composition. The increased moisture produces more hydrogen from the water shift reaction. Also, some of this hydrogen is a reactant in the methane reaction to generate more methane. Carbon monoxide is oxidized to carbon dioxide in the water shift reaction (McKendry, 2002).
These trends are supported by a performance evaluation using cottonwood as a feedstock,
Figure 2.5.
16
50 45 40 35 N2 30 CO 25 H2 20 CO2 15 CH4 10
Gas CompositionGas (mole %) 5 0 0 5 10 15 20 25 Moisture Content, Wet Basis (%)
Figure 2.5: Gas composition as a function of moisture content using cottonwood as fuel (Chee, 1987).
The energy content of the product gas is the third metric used to evaluate gasifier
performance. It can be calculated directly from the gas composition by adding the higher
heating value, HHV, of all combustible components of the product gas, weighted by their
mole fractions. Product gas from air gasification, as opposed to pure oxygen gasification
for example, is defined as a low energy gas because of the high nitrogen content. Low
energy gas is defined as gas having an energy content in the range of 4 – 6 megajoules
3 per normal cubic meter, MJ/Nm (McKendry 2002). This low energy gas can be combusted to heat air or water, or to power an engine. When pure oxygen is used in place of air, the product gas energy content is in the range of 12 – 18 MJ/Nm 3. This gas
17 can be used for synthesizing chemicals like methanol. Various experimental product gas
energy contents for woody biomass in a downdraft gasifier are presented in Table 2.3.
Table 2.3: Typical energy contents of product gas in downdraft gasifiers. Moisture Energy Content Fuel Content, wet Source (MJ/Nm 3) basis (%) General Biomass Not Reported 5.5 Reed & Das (1988) Rosewood 7.3 6.34 Sheth & Babu (2009) Furniture Wood & Not Reported 5.62 Zainal et al. (2002) Charcoal Wood 12 – 20 5.00 – 5.86 Rajvanshi (1986) Cottenwood 14.0 6.04 Chee (1987) Maple 12.0 5.55 Chee (1987) Black Locust 13.5 6.08 Chee (1987) Oak 13.8 6.12 Chee (1987)
The energy content of the product gas also changes as a function of moisture content of the fuel. Even though hydrogen content is expected to increase with wetter fuel due to the water shift reaction, the decrease of carbon monoxide leads to an overall decrease in energy content of the product gas, compared to the same fuel type being gasified with less moisture (McKendry, 2002). Schlapher in 1937, and Heywood in
1943, as cited in Reed & Das (1988) show that as biomass moisture content decreases from 20% to 0%, the energy content in the product gas increases from 4.3 MJ/m 3 to 5.1
MJ/m 3. Chee (1987) reports a slight, but not statistically significant, increase in energy content as the moisture content is decreased, Figure 2.6.
18
6.5 6.0 5.5 5.0 4.5 Content (MJ/m^3) (MJ/m^3) Content
Product Gas Energy Energy Gas Product 4.0 0 5 10 15 20 25 Moisture Content of Fuel, Wet Basis (%)
Figure 2.6: Energy content of product gas as a function of moisture content using cottonwood as a fuel source (Chee 1987).
One of the most important metrics in evaluating a gasifier is the efficiency, the fourth performance evaluation metric for this thesis. The cold gas efficiency, CGE, is used in this thesis, and is defined by Equation 2.2 (Rao et al., 2004). The CGE is the fraction of energy, originally in the solid fuel, that is now in the product gas and does not include the final conversion to electricity. Various CGE values for biomass in a downdraft gasifier are presented in Table 2.4.
HHV of gas (MJ) CGE = 2.2 HHV of fuel (MJ)
19 Table 2.4: Cold gas efficiencies for biomass in downdraft gasifiers. Moisture Cold Gas Fuel Content, wet Source Efficiency (%) basis (%) Rosewood 7.3 56.87 Sheth & Babu (2009) Wood Average Not reported 60 - 70 Rajvanshi (1986) Cottenwood 14.0 73 Chee (1987) Maple 12.0 65 Chee (1987) Black Locust 13.5 68 Chee (1987) Oak 13.8 65 Chee (1987) Furniture Wood & Not reported 80.9 Zainal et al. (2002) Charcoal Wood Chips < 20 > 75 Ankur Scientific (2008)
The CGE also changes with moisture content. Ptasinski et al. (2006) performed a theoretical analysis on an idealized gasifier using the modeling software Aspen Plus.
Their model shows that efficiency increases as the biomass is dried from 33% to 11%, although the increase levels off as the fuel becomes drier than 20% moisture content, as shown in Figure 2.7. The relatively flat efficiency curve in the 11 – 20% moisture content range is supported by experiment, Figure 2.8.
Figure 2.7: Gasification efficiency as a function of moisture content (Ptasinski et al., 2006).
20
100 90 80 70 60 50 40 30 20 Cold Gas Efficiency (%) 10 0 0 5 10 15 20 25 Moisture Content of Fuel, Wet Basis (%)
Figure 2.8: Cold gas efficiency as a function of moisture content using cottonwood as a fuel source (Chee 1987).
Product gas purity is critical to the end use of the gas, especially if it is to be used
in an internal combustion engine or gas turbine to generate electricity, and is the fifth
performance evaluation metric used in this thesis. Tars and particulate matter are the
important two categories of gas impurities. Particulate matter is any char, ash, or
biomass that remains after the product gas passes through the filtration system on the
gasifier. The term “tar” is used loosely in the literature, but Milne et al. (1998) gives a
general definition as, “The organics, produced under thermal or partial-oxidation regimes
(gasification) of any organic material, are called “tars” and are generally assumed to be
largely aromatic.”
Downdraft gasifiers are known for producing low tar gas, but their gas is far from tar free. This measurement varies widely among downdraft gasifiers, with one survey reporting a range of 500 – 3000 mg/Nm 3 (Reed & Das, 1988). Other claims are much
21 lower, however. Schmidt and Vasa (2000) claim that Ankur gasifiers generate a product
gas with less than 5 mg/Nm 3.
In the following chapter, the gasifier used in this thesis is presented along with a summary of its operation. All methods used to conduct the experiments and evaluate the gasifier’s performance are given.
CHAPTER 3. METHODS AND OPERATION
In this chapter, the methods used to evaluate the performance of the Ankur
WBG20 downdraft gasifier are presented. First, the independent and dependent variables are briefly discussed. Second, the Ankur downdraft gasifier used in this thesis is presented along with a summary of gasifier operation. Third, the instrumentation installed on this gasifier is presented, including the sample line system that delivers product gas to the gas chromatograph. Fourth, all data collection procedures are outlined, including fuel preparation and product gas analysis methods. Fifth, a derivation of the equation used to determine the Cold Gas Efficiency of this particular gasifier is given.
Finally, the performance evaluation criteria are presented.
Variables
Using a constant fuel source at each of several moisture contents, the operation
and performance of the gasifier was investigated. The fuel was Douglas Fir, Pseudotsuga
menziesii, woodchips with moisture contents, on a wet basis, of approximately 6%, 13%,
and 22%. These wood chips were sieved to control the particle size distribution. Since
the fuel type and size were held constant, the independent variable was fuel moisture
content.
The dependent variables were the product gas composition as well as product gas
purity. Also, product gas flow rate, fuel consumption rate, and char-ash production were
monitored. The relationship between these variables determined how the gasifier
22 23 performed, which was quantified by measuring the cold gas efficiency, equivalence ratio,
energy content of product gas, and fuel consumption rate for each experiment.
Experimental Setup – Gasifier Operation
An Ankur WBG20 downdraft gasifier was used to conduct the experiments, as
shown in Figure 3.1. The rating for this gasifier is 11 kWe, but electric power output was
not determined. The gasifier was operated in thermal mode only and no thermal rating
was given in the Operations Manual. Additional specifications for this gasifier are given
in Table 3.1.
Table 3.1: Ankur WBG20 specifications from the Operations Manual, (Ankur Scientific 2008). Model WBG-20 in scrubbed, clean gas mode. Mode 11 kWe in 100% producer gas mode. Gas Flow 50 NM 3/hr (880 standard liters/minute, SLM) Gasifier Type Downdraft Average Gas Calorific Value 1000 Kcal/Nm 3 (4.18 MJ/Nm 3) Gasification Temperature 1050 – 1100 ºC Wood / woody waste with maximum dimension Fuel Type and Size not exceeding 25mm Moisture Content in Biomass Fuel Less than 20% on a wet basis Rated Hourly Consumption 13-15 kg Typical Conversion Efficiency > 75%
24
Figure 3.1: Ankur WBG20 downdraft gasifier installed at Schatz Energy Research Center. The fuel feed door, fuel hopper, reactor, filtration system, and water scrubber system are shown.
25 A process diagram of the Ankur gasifier as installed at the Schatz Energy
Research Center is presented in Figure 3.2. The main components that make up the gasifier system are labeled and are discussed below in a summary of the operation of the gasifier.
Figure 3.2: Process diagram of Ankur gasifier as installed
For each experiment, all operators wore personal carbon monoxide detectors, and the three carbon monoxide detectors in the gasifier building were checked for proper functionality prior to each experiment. For gasifier start up, a propane pilot light on the burner would be ignited, the water scrubber system would be activated by starting the
26 water pump, and the combustion air blower would be turned on. Via an ejector, starting the water pump also initiated air flow into the hopper and reactor. Once water was flowing through the scrubber system, a propane torch would be inserted into the air inlets to ignite the charcoal bed inside the gasifier. After ignition of the charcoal bed, both the gas blower and vibrator motor would be turned on. The vibrator motor helped to move the fuel through the hopper and helped to prevent blockages of fuel flow. When a product gas flame was evident at the gas burner, the gasifier was ready for operation.
Prepared fuel was loaded into the cone on top of the pneumatic feed door. This cone could hold approximately 10 kg of wood chips. When the operator was safely away from the top of the gasifier, the pneumatic feed door was opened and the fuel entered the hopper. The wood level sensor indicated when fuel needed to be added to the hopper, and sounded an alarm approximately every 30 minutes. This sensor contained a rotating fin inside the hopper and when this fin could rotate freely, it indicated there was no wood obstructing its path and a low fuel alarm would sound. To control the amount of fuel gasified, experiments would begin and end when the fuel in the hopper was at the level of activating this wood level sensor. In other words, the remaining fuel in the hopper below this sensor would serve as the initial condition for all experiments.
Two air inlets were located at the bottom of the hopper where the combustion zone was located. Here, fuel would partially combust to provide heat for pyrolysis of the rest of the fuel. The bottom of the fuel hopper contained a throat where all charcoal, gas, oils, and tars would pass into the reactor. Most tars would be cracked at this point, which is the primary advantage of the general downdraft gasifier design.
27 The reactor was where charcoal would be reduced into combustible gas. The bottom of the reactor bed consisted of a grate and a rotating comb rotor. Both the product gas and char ash would pass through this grate. The char ash would fall through this grate which was aided by both the vibrator motor and the comb rotor. The char ash would build up in the bottom of the reactor, under the grate, and this char ash could be removed by a set of pneumatic valves. When the top valve was opened, the char ash would fall into a collection vessel. After the top valve was closed, the bottom valve would be opened to allow the char ash to fall out of the gasifier. The two valve system was necessary to maintain the partial vacuum inside the gasifier and to prevent atmospheric air from combining with the product gas. The product gas exited the reactor at the gas outlet pipe. This product gas would now enter the scrubber and filtration section of the gasifier to be cooled and cleaned.
This gasifier’s filtration system consisted of three parts, as shown in Figure 3.3 and Figure 3.4. First, the water scrubber both cooled the product gas and removed large particles that did not fall to the bottom of the reactor. All product gas would pass through a water jet and small orifice, forming an ejector. The cooled product gas would then exit the scrubber at the top, and the water and particulate matter would fall into the first of four barrels that contained baffles. The baffles allowed the particulate matter in the water to settle. A filter was installed on the water hose at the end of the barrel system to further clean the water before it passed through the water pump again in a closed loop system.
Second, the sawdust filter removed tars and smaller particulate matter from the product gas that were not removed by the water scrubber. All product gas was forced
28 through a bed of sawdust that would be stirred before each experiment. When this sawdust would become saturated, it would be removed and fresh sawdust would be added. The indicator to change the sawdust was a pressure drop across this filter of 30 millimeters of water column, mmWC, or higher. Finally, the product gas would exit the sawdust filter and pass through a bag filter that removed most of the remaining particulate impurities. A new bag filter was installed prior to each experiment.
Figure 3.3: Water scrubber system showing water pump, water jet system, and the four baffled barrels that both store the water and allow particulate matter to settle.
29
Figure 3.4: Filtration system showing the sawdust filter and bag filter. The sample port is also shown.
At this point, a portion of the product gas was diverted in a sample line for analysis with the gas chromatograph, GC. Prior to analysis, this sample gas was cleaned further, which is explained in detail in the next section. After exiting the filtration system, the product gas then passed through the gas blower and out to the burner to be combusted. A combustion air blower was installed to aid in complete combustion of the product gas by adding more oxygen to the mix.
At the end of each experiment, the gasifier was shut down immediately after the wood level alarm sounded. This ensured that the next experiment would begin under the same startup conditions as the previous experiment. First, the vibrator motor and gas blower would be shut off. When the gas blower stopped rotating completely, the air inlets would be sealed off by activating their pneumatic caps. After this, a valve on the
30 product gas line, immediately after the gas blower, would be closed and the product gas
sample line would be sealed. This sealed off the gasifier from the outside environment
and prevented any residual product gas from escaping. Once the gasifier was sealed, the
combustion air blower would be shut off and the pilot light on the burner would be turned
off.
The following section describes the instrumentation that was installed on the
gasifier as well as the GC calibration methods.
Experimental Setup – Gasifier Instrumentation
A schematic diagram showing the instrumentation installed on the gasifier is presented in Figure 3.5. The locations of the thermocouples, differential pressure transducers, and mass flow meters are shown. Also, a schematic of the sample line to the
GC is given in this figure. Further cleaning of the product gas was necessary to maintain proper functionality of the GC.
31
Figure 3.5: Schematic of gasifier setup and instrumentation.
Thermocouples, TC, were installed to measure many temperatures throughout the gasifier, Table 3.2. TC 1 was installed to monitor the combustion zone temperature.
This temperature served as a check of the internal condition of the gasifier and if an overheating situation occurred, the operator would know and could shut down the experiment. TC 2 was installed to measure the temperature of the product gas before it was cooled by the water scrubber. TC 3 was installed to measure the product gas temperature after it passed through the scrubber. This temperature served as a check of the water scrubber’s functionality to ensure the safety of the operators as well as the rest of the filtration system. If the water scrubber system was not functioning properly, hot
32 product gas could damage filters and equipment downstream of that system. TC 4 was
installed to measure the post-filtration-system product gas temperature. This TC port was
also where a portion of the product gas was sampled and sent to the GC for analysis.
This temperature was used to determine the water content of the product gas assuming
100% saturation. TC 5 was installed on the burner to measure the burner flame
temperature. This temperature measurement was linked to the safety system, so that in
the event of a burner flame out, the gasifier would automatically shut down. Finally, TC
6 was installed to measure ambient temperature.
Table 3.2: Thermocouples used on gasifier. Temperature Thermocouple Type Range Precision Measurement Combustion zone 1 K -270 – 1372 ºC ± 2.2 ºC or 0.75% inside fuel hopper Pre-scrubber 2 K -270 – 1372 ºC ± 2.2 ºC or 0.75% product gas Post-scrubber 3 T -270 – 400 ºC ± 1.0 ºC or 0.75% product gas GC sample line 4 T -270 – 400 ºC ± 1.0 ºC or 0.75% product gas Burner flame 5 K -270 – 1372 ºC ± 2.2 ºC or 0.75% temperature Ambient 6 T -270 – 400 ºC ± 1.0 ºC or 0.75% temperature
Differential pressure transducers were installed to electronically measure the various pressure drops throughout the gasifier, as outlined in Table 3.3. These were
Envic Model DP-101SPD1-C-24VDC differential pressure transducers. They had a range of 0 – 300 mmWC and a precision of ±0.01 mmWC. There were also differential pressure manometers that served as an analog backup to the transducers, which had a
33 range of 0 – 300 mmWC and a precision of ± 1 mmWC. Only an analog manometer was
installed for the DP3 location. These pressure drop measurements served as real time
indicators of the state of the various subsystems on the gasifier during operation. In the
reactor and hopper, too low of a pressure drop could indicate either no fuel or a fuel
bridge in the hopper. Large pressure drops anywhere in the system would indicate a
blockage of gas flow.
Table 3.3: Pressure transducers and manometers on gasifier. Transducer/ Pressure Drop Expected Pressure Drop for manometer Normal Operation, mmWC* 1 Air Nozzle: Ambient to Inside Hopper 15-20 2 Reactor: Inside Hopper to Reactor Gas 30-50 Outlet 3 Water Scrubber: Reactor Gas Outlet to Unknown Sawdust Filter Entrance 4 Sawdust Filter: Sawdust Filter Entrance 10-12 to Sawdust Filter Exit 5 Bag Filter: Bag Filter Entrance to Bag 3-5 Filter Exit *Ankur Scientific (2008)
Two flow meters were used to measure product gas flows. First, the main product gas flow was determined with an orifice plate flow meter with a differential pressure transducer. An orifice plate was used because a mass flow meter would be damaged from the tar and particulate impurities in the product gas. The pressure transducer used on this flow meter was an Auto Tran Inc. Model 600D5, which had a voltage output of 0-
5 volts of direct current, VDC. This type of flow meter works by measuring a pressure drop across an orifice because flow rate is proportional to pressure drop. This orifice plate flow meter was calibrated with a conventional mass flow meter and atmospheric air.
34 Atmospheric air was passed through the orifice and the pressure drop was determined while measuring the corresponding flow using the conventional mass flow meter. This calibration had a standard error of 6.8 standard liters per minute, SLM, and is presented in Appendix B.1. Since the orifice plate flow meter was calibrated with atmospheric air, the product gas flow estimates from the gasifier were corrected based on the final gas composition. This flow correction factor is described in detail later in this chapter in
Methods – Calculating the Cold Gas Efficiency. The second flow meter, an MKS
Instruments Model 1179A, measured the sample gas flow in the line to the GC. It had a range of 0-1000 standard cubic centimeters per minute, sccm, and a precision of ± 1%.
Because this sample gas was subjected to further filtration and a moisture trap, this flow meter was a conventional mass flow meter. This flow meter was designed to measure nitrogen flow, but was calibrated to read product gas flow by use of a correction factor of
1.0325. The calibration is presented in Appendix B.2.
The product gas composition was determined by using an Agilent Micro GC. The sample line from the gasifier to the GC contained its own filtration system, as shown in
Figure 3.6, because gas entering the GC needed to be completely free of water, tars, and particulates.
35
Figure 3.6: Sample line filtration system for cleaning the product gas prior to analysis with the gas chromatograph.
The sample gas first passed through a Whatman GF/D, 25 mm glass microfiber filter, not shown in Figure 3.6, to remove any remaining tars and particulates that were not removed in the gasifier’s own filtration system. This filter was replaced as needed during experiments when the sample gas flow became too low or when oxygen began to appear in the sample gas composition indicating a leak. After this filter, the sample gas passed through a salt-ice bath to condense water vapor that was in the gas. A desiccant column, in line after the salt-ice bath, removed any remaining water vapor. There were
36 two more glass microfiber filters installed in the sample line, before and after the
desiccant column, respectively. This filtration system allowed completely tar free, dry
product gas to be sent to the GC for determination of gas composition.
To calibrate the GC, three separate gas sources of known composition were used.
The main constituents of the product gas for this gasifier were N 2, H 2, CO, CO 2, and CH 4.
Ankur specified the expected mole fractions of each gas in the product gas. Therefore, a
gas cylinder was purchased from Scott Specialty Gases in Plumsteadville, PA with each
of these five gases at their expected percentages, to serve as calibration gas, as shown in
Table 3.4. The GC was calibrated before each experiment with this calibration gas.
Table 3.4: Scott Specialty Gases calibration gas composition and Ankur’s expected gas composition . Scott Specialty Gases Ankur’s Expected Gas Percent Composition Gas Composition* N2 50.1 50 H2 17.8 18 ± 2 CO 18.01 19 ± 3 CO 2 9.02 10 ± 3 CH 4 5.01 ≤ 3 *Ankur Scientific (2008)
A trace amount of oxygen may be present in the product gas. Therefore,
atmospheric air was used to calibrate the GC for oxygen. This calibration was performed
before the series of experiments began, and was not performed before each individual
experiment.
37 Finally, trace amounts of ethene, ethane, and acetylene may also be contained in the product gas. Agilent, the manufacturer of the GC, supplied a cylinder of calibration gas with the GC that contained trace amounts of these three gases. Like oxygen, this calibration was performed before the series of experiments began, and was not performed before each individual experiment.
In the following section, the methods for fuel preparation are discussed. Also, the methods for determining fuel moisture content, tar and particulates in the product gas, fuel energy content, and product gas energy content are discussed.
Methods – Fuel Preparation and Data Collection
The fuel type used in these experiments was Douglas Fir wood chips. The wood chips were sieved through a one inch mesh screen to remove the large chips in order to prevent bridging in the gasifier. The large narrow chips that passed through the screen were removed by hand and all remaining wood chips were used as fuel for the experiment. Although the fuel had an upper limit on size, the remaining chips did have a non-uniform size distribution. Figure 3.7 shows a sample of sieved Douglas Fir wood chips that were used in the gasifier.
38
Figure 3.7: Sieved Douglas Fir wood chips.
For the 13% and 22% MC wood chip experiments, the fuel was solar dried. Thin layers of chips were spread out on large black tarps and the moisture content was checked daily. Once the chips attained the proper MC, they were immediately bagged to preserve the moisture. The bags of dried wood chips were on the order of 10 – 20 kg each.
The 6% MC wood chips were first solar dried. Since the wood chips could not achieve 6% MC in ambient air, they were further dried in a tumbler fitted with a Nauticus
250 desiccant dryer to attain 6% MC. A direct relationship exists between the relative humidity of the surrounding air and the steady state moisture content of the wood chips.
Therefore, the target relative humidity was controlled by the desiccant dryer and the wood chips reached their equilibrium moisture content. For 6% MC wood chips, the relative humidity on the desiccant dryer was set to 22%.
39 Moisture content was determined for this thesis on a wet basis, which is defined
by Equation 3.1. Conversely, moisture content determinations on a dry basis have the
mass of the dry chips in the denominator. In general, a pan of woodchips was weighed
first, and then dried in an oven at 105 °C overnight to drive off all moisture. The oven
dry chips were weighed and the MC was then determined, after subtracting the pan mass.
Mass - Mass Wet Chips Dry Chips MC (%) = ×100 3.1 Mass Wet Chips
For each MC determination, a representative sample of wood chips on the order of 100 g was collected in an aluminum pan. The wet chips were weighed on an ACB
Plus 600H scale, with a range of 0 – 600 g and a precision of 0.01 g. The chips were then dried overnight in an oven set to 105 ºC. The oven dry chips were immediately weighed after being taken out of the oven and the MC was then determined. Although some chips may have been drier and some may have been wetter due to the non-uniform size distribution, this method determined the bulk MC of the wood chips. During experimental operation, the MC of the wood chips was checked again by this method.
The tar and particulate matter in the product gas was measured from the gas that had already passed through the three filtration systems on the gasifier. The tar and particulate matter in the pre-scrubber gas immediately leaving the reactor was not measured. The portion of product gas that was diverted to the sample line for gas composition determination was used to measure the tar and particulate matter of the
40 filtered product gas. The sample line port was installed on the side of the product gas flow line and sampled the edge of gas flow and not the center. In other words, the sample line port did not protrude into the main product gas flow path and draw the sample from the center of this flow path. The sample port drew the gas from the edge, perpendicular to the main flow path of the product gas.
The tar and particulate matter present in the product gas were quantified by measuring the change in mass of the first glass microfiber filter on the sample line to the
GC divided by the total sample gas volume that passed through that filter. These filters and their holders were stored in a desiccant chamber prior to use. Before each experiment, the filters and holders were removed from the desiccant chamber, weighed, and assembled. Depending on the tar and particulate content of the gas, more than one filter could be used during an experiment. After each experiment, the filters and holders would be returned to the room temperature desiccant chamber to remove moisture. The filters and holders were weighed 24 hours later to determine the mass difference due to tar and particulate matter accumulation on the filter. The volume of gas that passed through each filter was determined by integrating the sample line’s mass flow meter readings over the duration that the respective filter was installed. This method provided the sum of tar and particulate matter in the product gas, in units of mg/m 3 of gas.
The energy content of the input fuel was determined with a Parr 1241 oxygen bomb calorimeter. Wood chips were first dried in an oven at 105 ºC overnight to drive off all moisture. For each calorimeter experiment, oven dry wood chips that totaled approximately 1 g were used. The wood was placed into the bomb which was then
41 pressurized with pure oxygen. This pressurized bomb was immersed into 2.00 kg of de- ionized water. After connecting electrodes to the bomb, a current ignited the fuse wire inside the bomb and the sample was completely combusted. The energy content of the wood was determined by the temperature change of the surrounding de-ionized water, after correcting for the fuse wire used. This method provided the higher heating value,
HHV, of the input fuel in units of MJ/kg.
The total amount of fuel consumed in each experiment was determined by
weighing each fuel addition with a Pelouze Model 4040 scale. This scale had a range of
0 – 180 kg and a precision of 0.2 kg. In addition to weighing the fuel additions, the
amount of remaining fuel in the hopper at the end of each experiment was controlled with
the use of the wood level sensor. This ensured that each experiment both began and
ended with the fuel level in the hopper at the same height.
The energy content of the product gas was determined by the sum of the HHV’s
of each component of the gas, weighted by the mole fraction of each component as
measured by the GC, in units of megajoules/standard liter, MJ/SL. The GC measured the
gas composition every five minutes. For each five minute GC interval, the gas
composition was averaged from the composition at the beginning and end of the period.
The total product gas flow for each GC interval was determined by integrating the orifice
plate flow meter readings for that interval, in units of Standard Liters, SL. A flow
correction factor was determined for each GC interval based on the gas composition
because the orifice plate flow meter was calibrated with atmospheric air. This correction
factor is described in the next section.
42 The equivalence ratio is a ratio of air-fuel ratios. It is the actual air-fuel ratio of the experiment divided by the air-fuel ratio needed for complete stoichiometric combustion of the biomass. As described in Chapter 2, the air-fuel ratio for complete combustion of biomass is 6.29. The actual air-fuel ratio of each experiment was estimated from the total nitrogen content of the product gas and the amount of fuel gasified. All nitrogen contained in the product gas was assumed to come from the atmospheric air entering the air inlets during each experiment and, based on the gas composition of atmospheric air, was assumed to be approximately 79% of the entering air. The total mass of entering air was estimated by the density of 20 ºC air at sea level,
1.2 kg/m 3. The actual air-fuel ratio was then determined by dividing the total mass of air
that entered the air inlets by the total mass of dry fuel that was gasified. The equivalence
ratio was then determined by dividing the actual air-fuel ratio by 6.29.
The energy content of the char-ash produced by the gasifier was determined using
the bomb calorimeter with the same method described for determining the energy content
of the input fuel. The total mass of char-ash was collected for all experiments conducted
at each MC, giving a production quantity for each experimental set. The method for
determining the cold gas efficiency of the gasifier is outlined in the following section.
Methods – Calculating the Cold Gas Efficiency
The cold gas efficiency is defined as the total energy contained in the product gas divided by the total energy contained in the input fuel. The method that was used to calculate the cold gas efficiency for this particular gasifier is presented below.
43 Since oxygen in the product gas was assumed to be an impurity from air entering the sample line, it was removed from the product gas composition. Furthermore, since air is approximately 20% oxygen and 79% nitrogen, the nitrogen component of the product gas needed to be adjusted to remove the presumed component from air. The adjusted nitrogen component was found by Equation 3.2.
yO y' = y '' −y = y '' − 2 ∗ 79.0 3.2 n n nair n 20.0 where
y'n = adjusted mole fraction of nitrogen
y ''n = mole fraction of nitrogen as recorded by the GC y = presumed mole fraction of nitrogen from air leak n air y = mole fraction of oxygen as recorded by the GC O 2
The nitrogen and oxygen from the presumed air leak were then removed from the product gas composition, and the mole fractions were adjusted accordingly by Equation
3.3.
y '' i y'i = 3.3 n y '' −y − y ∑ j O2 nair j=1 where
y'i = adjusted mole fraction of gas component i
y ''i = mole fraction of gas component i as recorded by the GC, including the adjusted nitrogen from Equation 3.2, and excluding y and y . O 2 n air
y '' j = mole fraction of gas component j as recorded by the GC, including the adjusted nitrogen from Equation 3.2. y = mole fraction of oxygen O 2 y = mole fraction of nitrogen from air n air n = total number of gas components
44 Also, since the GC sampled dry gas, the water vapor in the original product gas must be included. It was assumed that the product gas was saturated at the sample line port on the gasifier. Therefore, the mole fraction of water vapor could be estimated from the product gas temperature using a polynomial approximation of the water saturation curve, given in Equation 3.4.
RH y = ⋅ (b + b ⋅T + b ⋅T 2 + b ⋅T 3 ) 3.4 H 2O P 0 1 2 3 where y = estimated molar fraction of water vapor H 2O RH = 100% relative humidity T = sample gas temperature (°C) P = atmospheric pressure, assumed constant = 101.325 kPa b0 = constant = -0.488822 b1 = constant = 0.07205565 b2 = constant = -0.0002694052 -7 b3 = constant = 5.992389•10
With this estimate, the mole fractions of the other gases were adjusted accordingly from the addition of the water vapor, Equation 3.5.
y = y' ⋅(1− y ) 3.5 i i H 2O where
yi = corrected mole fraction of gas component i
y'i = mole fraction of gas component i from Equation 3.3 y = estimated mole fraction of water vapor H 2O
The orifice flow correction factor, CF, could now be calculated with the corrected
product gas composition entering the sample line. Both air and the product gas were
assumed to be ideal gases. The CF is the square root of the ratio of air to product gas
densities, as given in Equation 3.6, Table 3.5.
45
Pair 1 ρ R ⋅T R ⋅T CF = air = air air = air air 3.6 k k ρ pg Pgas yi 1 yi ⋅ ∑ ⋅ ∑ Tgas i=1 Ri Tgas i=1 Ri where P = pressure at the orifice (kPa) assumed constant Tair = calibration air temperature at the orifice (K) = 291.4 K Tgas = product gas temperature at the orifice (K) Rair = ideal gas constant for air [ kJ/(kg•K) ] yi = corrected mole fraction of component i Ri = ideal gas constant for component i [ kJ/(kg•K) ]
Table 3.5: Gas properties (Sonntag et al., 2003) Gas R (kJ/kg K) HHV (kJ/mole)
N2 0.29680 H2 4.12418 285.84 CO 0.29683 282.99 CO 2 0.18892 CH 4 0.51835 890.36
C2H4 0.29637 1410.97 C2H6 0.27650 1559.90 C2H2 0.31931 1299.60 H2O 0.46152 O2 0.25980
For each five minute GC interval, a correction factor was calculated and applied to the orifice plate flow readings for that interval. Flow readings were generated approximately every second, so each GC interval contained about 300 data points for product gas flow. The volume of product gas generated by the gasifier was determined for each GC interval, as shown in Equation 3.7.
46 n 60 min Q = CF ⋅Q ⋅ t − t ⋅ Corr ∑ i ()i i−1 3.7 i=2 1 hr where QCorr = volume of product gas in GC Interval (SL) CF = correction factor for GC Interval Qi = orifice flow rate for current data point (SLM.) ti = time stamp of current data point (hrs.) ti-1 = time stamp of previous data point (hrs.) n = number of data points in GC Interval
The higher heating value, HHV, of the product gas was calculated for each GC
measurement, as given in Equation 3.8, using values from Table 3.5. In general, the
HHV is energy per mol, volume, or mass. Here, the HHV of each combustible
component of the product gas is reported as kJ/mol, and the total HHV of the product gas
is converted to MJ/SL via Equation 3.8.
1 MJ 1 mol k HHV pg = ⋅ ∑()HHV i ⋅ yi 3.8 1000 kJ 22.4 SL i=1 where HHV pg = estimated HHV of product gas (MJ/SL) HHV i = HHV of combustible component i (kJ/mol) yi = corrected mole fraction of combustible component i k = number of combustible components in product gas
The energy of the input fuel was determined by Equation 3.9. In this equation, since the input fuel is in the solid state, the HHV is reported as MJ/kg.
E fuel = mdry ⋅ HHV fuel 3.9 where Efuel = energy content of fuel (MJ) mdry = dry mass of fuel (kg) HHV fuel = higher heating value of dry fuel (MJ/kg)
47 Finally, the cold gas efficiency, CGE, was determined by Equation 3.10.
nGC −1 HHV + HHV pg ,i+1 pg ,i ∑ Qcorr ,i ⋅ E pg i=1 2 CGE = = 3.10 E n _ fuel MC fuel i ∑ mi ⋅1− ⋅ HHV fuel i=1 100 where
Epg = total energy content of product gas for an experiment (MJ) th th Qcorr,i = Total gas flow of product gas over the GC interval between the i and i+1 GC samples (SL) th HHV pg,i = HHV for the i GC sample (MJ/SL) nGC = number of GC samples taken during an experiment Efuel = total energy content of fuel added during an experiment (MJ) th mi = mass of fuel added to hopper in i addition (kg) th MC i = moisture content (wet basis) of the i fuel addition to the hopper (%) HHV fuel = HHV of the dry fuel (assumed constant for a type of fuel) (MJ/kg) nfuel = number of fuel additions during a run
Methods – Performance Evaluation
A total of 10 experiments were conducted for this performance evaluation.
The gasifier was evaluated by comparing its performance parameters while operating with a constant fuel type over a range of moisture contents. Although the MC was checked during the drying process, the MC of each bag of fuel used in the experiments was re-measured by taking a sample of fuel immediately before the fuel was loaded into the gasifier. The cold gas efficiency, equivalence ratio, gas composition, energy content of product gas, and fuel consumption rate were plotted versus moisture content to measure and compare the performance of the gasifier. Also, the thermal output power was plotted versus time for each experiment.
48 Within each experiment, the efficiency interval was defined as the time interval where both steady state gas production was reached and where fuel consumption could be effectively determined. All analyses for each experiment were performed on data collected during the efficiency interval, except char-ash production and tar and particulate content of the product gas. These analyses were performed on the total run time for each experiment, because the gasifier was always generating char-ash during operation and the glass microfiber filters were always collecting the tar and particulate matter during operation.
The results of the 10 experiments are presented in the next chapter. These results also include a summary of the various maintenance issues that were encountered during gasifier operation.
CHAPTER 4: RESULTS
In this chapter, all results are presented. First, the rationale for conducting ten experimental runs of the gasifier is presented. Second, a product gas temperature adjustment for two experiments is presented. Third, the efficiency interval for each experiment is presented, which was the time during each experiment in which most data analysis was performed. Fourth, the results for the five performance metrics described in
Chapter 2 are presented: equivalence ratio, product gas composition, product gas energy content, cold gas efficiency, and product gas purity. In addition to these five performance metrics, results for fuel consumption rates, thermal output power, and char- ash production are presented. Finally, a summary of the maintenance issues that were encountered during experimental operation, and the steps taken to resolve each issue, is presented.
Originally, nine experimental runs of the gasifier were planned: three at 6% MC, three at 13% MC, and three at 22% MC. A total of ten experimental runs of the gasifier were conducted, however. The first three experiments were conducted at approximately
13% MC. After these experiments were conducted, the originally supplied bag filters from Ankur were replaced by a similar bag filter available in the United States. After this change in filter type was implemented, three experiments were conducted at approximately 22% MC followed by three at approximately 6% MC. A final experiment at 13% MC was conducted with the new bag filter as a check of the performance of the
49 50 new filter compared to the original filter. Therefore, a total of 10 experiments were conducted.
The product gas temperature was used both in determining the water content of the gas as well as determining the product gas flow correction factor. The thermocouple measuring the product gas temperature was placed too far from the sample port and orifice plate flow meter for the first two 13% MC experiments, however. This resulted in erroneous product gas temperature readings. The thermocouple was repositioned for the last eight experiments. Therefore, the product gas temperature profile for the first two
13% MC experiments was estimated by using the product gas temperature profiles of the other two 13% MC experiments, and is described in Appendix C.
Efficiency Interval and Its Determination
The efficiency interval for each experiment is defined as the interval during which all analyses were made, with the exception of determining char-ash production and tar and particulate concentrations. This was the interval where steady state GC data were available and where fuel consumption could be determined. The time between successive wood level alarms was longer than the time between successive GC readings.
This was true because the GC recorded data every five minutes while the wood level sensor sounded and alarm to add fuel approximately every 30 minutes. Therefore, if the efficiency interval began after fuel was loaded, then the fuel consumed in this portion of the efficiency interval was prorated by time. For example, if the first fuel loading cycle was 30 minutes and the GC data collection started 15 minutes into this interval, then the
51 fuel consumption for this portion of the efficiency interval was assumed to be 15/30, or ½ of the fuel loaded. Furthermore, the gas flow measurements were recorded every second.
If an efficiency interval ended in the middle of a GC reading, the total gas flow for that five minute interval was integrated for only the portion within the efficiency interval, not the total five minutes. The efficiency interval times for each experiment are presented in
Table 4.1. Raw data for each experiment are presented in Appendix A, in the order of experiments as presented in Table 4.1.
Table 4.1: Time of efficiency intervals for each experiment. Average Moisture Content Experiment Efficiency Interval Average of Fuel, Wet Basis Time (Hours) (Hours) 5.70% 1 2.17 5.80% 2 2.50 2.50 5.50% 3 2.83 13.40% 1 2.65 12.20% 2 3.47 3.24 12.80% 3 3.25 12.50% 4 3.00 22.60% 1 2.67 21.60% 2 3.60 3.02 21.50% 3 2.80 All Experiments 2.89
Equivalence Ratio
The equivalence ratio was determined by using the general formula for biomass,
CH 1.4 O0.6 , and by using the nitrogen in the product gas as a tracer to determine the amount of air that entered the gasifier as described in Chapter 3. These results are presented in Figure 4.1 and Table 4.2.
52
0.40 0.35 0.30 0.25 0.20 y = 0.6069x + 0.1909 0.15 R2 = 0.9441 0.10 Equivalence Ratio 0.05 0.00 0% 5% 10% 15% 20% 25% Moisture Content of Fuel, Wet Basis (%)
Figure 4.1: Equivalence ratio vs. moisture content of fuel.
Table 4.2: Equivalence ratio for each experiment. Average Moisture Content Experiment Equivalence Ratio Average of Fuel, Wet Basis 5.70% 1 0.237 5.80% 2 0.227 0.231 5.50% 3 0.228 13.40% 1 0.263 12.20% 2 0.263 0.261 12.80% 3 0.263 12.50% 4 0.254 22.60% 1 0.321 21.60% 2 0.324 0.328 21.50% 3 0.341
Gas Composition
The composition of the product gas was determined by GC at five minute
intervals. The five principal gases in the product gas were nitrogen, carbon monoxide,
hydrogen, carbon dioxide, and methane. In addition to these, trace amounts of oxygen,
53 acetylene, ethane, and ethylene were also present. Oxygen was assumed to be present due to an air leak in the sample line, which occured when the microfiber filter collecting tar and particulates would become blocked and need to be replaced. Oxygen, and the corresponding nitrogen, was subtracted and the concentrations of the remaining gases were adjusted accordingly. Also, the product gas was assumed to be saturated with water vapor, so the water vapor concentration was estimated from the temperature of the sample gas using the water saturation curve. The concentrations of the other gases were adjusted accordingly for the presence of water vapor.
Figure 4.2 illustrates the variation of the five principal components of the product gas versus moisture content, after subtracting the oxygen/nitrogen from the air leak and adding the water vapor. Each principal component is plotted separately in Figures 4.3 –
4.7, with trendlines added. The complete product gas compositions are presented in
Table 4.3, after subtracting the oxygen/nitrogen from the air leak and adding the water vapor. These data are the average gas compositions for each efficiency interval for each experiment, as the GC recorded data every five minutes. All composition values are mole fractions.
54
60
50
40 Hydrogen Carbon Monoxide 30 Carbon Dioxide Methane Nitrogen 20
10 Percent Composition of Gas (%) Gas of Composition Percent 0 0% 5% 10% 15% 20% 25% Moisture Content of Fuel, Wet Basis (%)
Figure 4.2: Average product gas composition vs. moisture content of fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel.
60
50
40
30 y = 34.785x + 44.279 R2 = 0.9165
20
10 Percent Composition of Gas (%) 0 0% 5% 10% 15% 20% 25% Moisture Content of Fuel, Wet Basis (%)
Figure 4.3: Average product gas nitrogen content vs. moisture content of fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel.
55
60
50
y = -42.744x + 27.38 40 R2 = 0.9596
30
20
10 Percent Composition of Gas (%) 0 0% 5% 10% 15% 20% 25% Moisture Content of Fuel, Wet Basis (%)
Figure 4.4: Average product gas carbon monoxide content vs. moisture content of fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel.
60
50
40
y = -6.5551x + 13.917 30 R2 = 0.4771
20
10 Percent Composition of Gas (%) 0 0% 5% 10% 15% 20% 25% Moisture Content of Fuel, Wet Basis (%)
Figure 4.5: Average product gas hydrogen content vs. moisture content of fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel.
56
60
50
40
y = 19.917x + 8.8991 30 R2 = 0.9655
20
10 Percent Composition of Gas (%) 0 0% 5% 10% 15% 20% 25% Moisture Content of Fuel, Wet Basis (%)
Figure 4.6: Average product gas carbon dioxide content vs. moisture content of fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel.
60
50
40
y = -3.1373x + 2.8006 30 R2 = 0.6966
20
10 Percent Composition of Gas (%) 0 0% 5% 10% 15% 20% 25% Moisture Content of Fuel, Wet Basis (%)
Figure 4.7: Average product gas methane content vs. moisture content of fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel.
57 Table 4.3: Complete average product gas composition, %, and standard deviation for 10 experimental gasifier runs using Douglas Fir woodchips as fuel. Average MC of H20 H20 H2 H2 N2 N2 CH 4 CH 4 Fuel, Ave. St. Ave. St. Ave. St. Ave. St. Wet Dev Dev Dev. Dev. Basis 5.70% 1.47 0.27 13.70 0.54 46.72 0.95 2.47 0.25 5.80% 1.56 0.36 13.28 0.53 46.69 0.91 2.55 0.28 5.50% 1.77 0.46 13.14 0.54 47.00 1.22 2.62 0.30 13.40% 1.47 0.40 13.57 0.66 48.14 1.49 2.29 0.17 12.20% 1.62 0.43 13.49 0.74 47.89 1.47 2.45 0.24 12.80% 1.39 0.35 13.01 0.42 48.03 0.99 2.62 0.28 12.50% 1.83 0.40 13.21 0.32 47.76 0.61 2.64 0.20 22.60% 1.42 0.34 12.50 1.14 52.03 1.78 2.06 0.20 21.60% 1.53 0.43 11.53 0.67 52.58 1.88 2.17 0.26 21.50% 1.45 0.52 12.98 0.59 52.43 1.49 1.95 0.23
Average MC of CO CO CO 2 CO 2 C2H4 C2H4 C2H6 C2H6 C2H2 C2H2 Fuel, Ave. St. Ave. St. Ave. St. Ave. St. Ave. St. Wet Dev. Dev Dev. Dev. Dev. Basis 5.70% 24.82 1.13 9.95 0.78 0.62 0.06 0.08 0.01 0.17 0.01 5.80% 25.13 0.84 9.87 0.55 0.66 0.08 0.09 0.02 0.18 0.02 5.50% 24.20 1.15 10.31 0.72 0.69 0.09 0.09 0.02 0.19 0.03 13.40% 22.44 0.95 11.22 0.48 0.62 0.06 0.08 0.01 0.16 0.01 12.20% 22.32 1.21 11.32 0.61 0.66 0.07 0.08 0.01 0.17 0.03 12.80% 22.22 0.88 11.69 0.52 0.74 0.10 0.09 0.02 0.20 0.02 12.50% 22.21 0.90 11.36 0.54 0.74 0.07 0.09 0.01 0.18 0.02 22.60% 18.22 1.39 13.06 0.99 0.54 0.07 0.07 0.01 0.11 0.03 21.60% 18.07 1.32 13.30 0.59 0.59 0.08 0.08 0.02 0.14 0.04 21.50% 17.05 0.95 13.53 0.41 0.47 0.08 0.06 0.02 0.08 0.02
58 Energy Content
The energy content of the product gas is a function of its composition. Each combustible component of the product gas has an energy content defined as the higher heating value, HHV. The total energy content of the product gas is the sum of the HHV’s of each combustible component, weighed by the mole fractions of each component. The results are presented in Figure 4.8 and Table 4.4. The results reported here are the average product gas energy contents for each experiment. For each five minute GC interval, the energy content was averaged from the two gas compositions as reported by the GC at the beginning and end of each GC interval, available in Appendix A.
7
6
5 y = -38.667x 2 + 2.4683x + 6.413 4 R2 = 0.9744
3
Gas (MJ/m^3) Gas 2
1 Higher Heating Value of Product Product HigherHeating of Value 0 0% 5% 10% 15% 20% 25% Moisture Content of Fuel, Wet Basis (%)
Figure 4.8: Average energy content of product gas vs. moisture content of fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel.
59 Table 4.4: Average energy content of product gas for 10 experimental gasifier runs using Douglas Fir woodchips as fuel. Average Moisture Content Experiment Average Energy Standard Deviation of Fuel, Wet Basis Content (MJ/m 3) (MJ/m 3) 5.70% 1 6.42 0.16 5.80% 2 6.47 0.15 5.50% 3 6.39 0.19 13.40% 1 6.03 0.18 12.20% 2 6.09 0.23 12.80% 3 6.16 0.14 12.50% 4 6.17 0.10 22.60% 1 5.17 0.24 21.60% 2 5.12 0.28 21.50% 3 4.97 0.20
Cold Gas Efficiency
The average energy content of the oven dry Douglas Fir wood chips, determined via bomb calorimeter, was 20.16 MJ/kg and was assumed constant for all experiments.
The wood chips used in the experiments arrived in two lots of approximately one ton each. Three energy content determinations were made for each lot of woodchips, and the results are presented in Table 4.5. The energy, MJ, of the product gas was determined for each GC interval by multiplying the total gas flow, m 3, in the respective interval by the average energy content of the product gas, MJ/m 3, for that interval. The total product gas energy for each efficiency interval was the sum of the product gas energy contained in each GC interval. The cold gas efficiency, the ratio of energy in the product gas to energy in the input fuel, is presented in Figure 4.9 and Table 4.6.
60 Table 4.5: Energy content of oven dry Douglas Fir woodchips. Fusewire Mass Temp Temp HHV Sample final initial Consumed (g) (ºC) (ºC) (MJ/kg) (cal) 1 0.987 26.300 24.340 11 19.99 1st 2 1.011 27.533 25.515 16 20.06 Lot 3 1.028 28.486 26.440 9 20.02 1 1.004 27.418 25.380 18 20.39 2nd 2 1.047 29.192 27.108 17 20.01 Lot 3 1.020 27.125 25.044 19 20.50 Average 20.16 Standard Deviation 0.22
100%
80%
60% y = 0.0085x + 0.6558 40% R2 = 0.0009 20%
0% Cold Gas Efficiency (%) Efficiency Gas Cold 0% 5% 10% 15% 20% 25% Moisture Content of Fuel, Wet Basis (%)
Figure 4.9: Cold gas efficiency vs. moisture content of input fuel for 10 experimental gasifier runs using Douglas Fir woodchips as fuel.
61 Table 4.6: Cold gas efficiency for each experiment. Average Moisture Cold Gas Standard Average Content of Fuel, Experiment Efficiency Deviation (%) Wet Basis (%) (%) 5.70% 1 66.0% 64.3% 1.55% 5.80% 2 63.8%
5.50% 3 63.0% 13.40% 1 66.8%
12.20% 2 68.1% 67.5% 0.97% 12.80% 3 68.5%
12.50% 4 66.5% 22.60% 1 64.7% 21.60% 2 63.8% 64.7% 0.95% 21.50% 3 65.7% Average 65.7% Standard Deviation 1.86%
Tars and Particulates
The tars and particulates in the product gas were determined by mass difference
of glass microfiber filters on the sample line to the GC. The filters were changed when
they became blocked. Therefore, some experiments used more filters than others. A
mass flow meter on the sample line was used to determine the amount of product gas that
passed through each filter. These values are for the total amount of tars and particulates
only, and were not separated into each component. A tar/particulate value was
determined for each filter, and the results are presented as such. It was not feasible to
extrapolate these data to the efficiency interval only, as these data were collected during
the entire run time of each experiment. The results are presented in Figure 4.10, Table
4.7, and Table 4.8.
62
1200
1000
800
600
400 y = -2058.7x + 861.22 200 2
Tar and in Tar Particulates R = 0.3109 ProductGas (mg/m^3) 0 0% 5% 10% 15% 20% 25% Moisture Content of Fuel, Wet Basis (%)
Figure 4.10: Tars and particulates in product gas vs. moisture content of input fuel for n = 26 determinations.
Table 4.7: Tars and particulate matter in product gas for each experiment. Average Moisture Content of Fuel, Wet Experiment Tars and Particulate Matter (mg/m 3) Basis Filter 1 Filter 2 Filter 3 Filter 4 5.70% 1 543 849 5.80% 2 890 645 733 455 5.50% 3 973 747 689 844 13.40% 1 678 908 12.20% 2 348 434 12.80% 3 442 621 12.50% 4 900 543 699 22.60% 1 310 21.60% 2 518 481 917 21.50% 3 230 152 189
63 Table 4.8: Average tar and particulate matter for each experiment, and for each set of moisture content experiments. Average Moisture Average Average Standard Experiment Content of (mg/m 3) (mg/m 3) Deviation Fuel, Wet Basis 5.70% 1 696 5.80% 2 681 737 160 5.50% 3 813 13.40% 1 793 12.20% 2 391 619 199 12.80% 3 532 12.50% 4 714 22.60% 1 310 21.60% 2 639 400 268 21.50% 3 190
Fuel Consumption
The fuel consumption rate for each experiment was determined for the dry biomass consumed and did not include the mass of water contained in the fuel. These results are for the efficiency interval only, and the relationship between dry fuel consumption rate and moisture content of fuel is presented in Figure 4.11 and Table 4.9.
25
20
15 y = -39.582x + 23.197
(kg/hr) 10 R2 = 0.8721 5
0 Dry FuelDry Consumption Rate 0% 5% 10% 15% 20% 25% Moisture Content of Fuel, Wet Basis (%)
Figure 4.11: Dry fuel consumption rate vs. moisture content of fuel.
64 Table 4.9: Dry fuel consumption rate for each experiment during efficiency interval. Average Moisture Dry Fuel Standard Average Content of Fuel, Experiment Consumption Deviation (kg/hr) Wet Basis Rate (kg/hr) (kg/hr) 5.70% 1 21.5 5.80% 2 20.4 20.7 0.7 5.50% 3 20.3 13.40% 1 19.2 12.20% 2 19.0 18.5 0.8 12.80% 3 17.5 12.50% 4 18.3 22.60% 1 14.7 21.60% 2 12.5 14.3 1.6 21.50% 3 15.7
Thermal Output Power
The thermal output power is a function of both the energy content of the product
gas and total gas flow. For each GC interval, the total gas flow was determined from the
orifice plate flow meter readings. The total energy contained in the product gas was
determined by multiplying the total flow by the average energy content of the product gas
in each GC interval. Therefore, the thermal output power was determined for each GC
interval and was plotted over time as shown in Figure 4.12.
65
MC 90 5.7% 80 5.8% 5.5% 70 13.4% 12.2% 60 12.8% 50 12.5% 22.6% 40 21.6% 21.5% 30
Gasifier Output(kWth) Power Gasifier 0 1 2 3 Cumulative Run Time (hr)
Figure 4.12: Thermal output power vs. efficiency interval run time for each experiment.
Char-Ash
As will be discussed later in this chapter, the char-ash measurement was difficult to make. The first three 13% MC experiments were conducted first, and only the third experiment produced a measurement. For the 6% and 22% MC sets, the total char-ash was collected after each set of experiments were conducted. These data were collected during the entire run time for the experiments as opposed to just the efficiency interval, and the results are shown in Table 4.10. The char-ash energy content was determined using the bomb calorimeter and was found to be 30.9 MJ/kg. Three determinations were made, and the resulting energy content was assumed to be a constant. The results are presented in Table 4.11.
66 Table 4.10: Char-ash percentages for each set of MC experiments. Total dry fuel Percentage of Experiment Char-ash (kg) gasified (kg) original dry fuel All 6% runs 205.3 15.5 7.5% 13% run 3 64 2.6 4.1% All 22% runs 146 8.18 5.6%
Table 4.11: Energy content of char-ash generated in Ankur gasifier. Fusewire Mass Temp Temp HHV Sample final initial Consumed (g) (ºC) (ºC) (MJ/kg) (cal) 1 1.0456 27.870 24.695 18 30.55 2 0.9602 28.015 25.040 18 31.16 3 1.0060 29.340 26.245 18 30.95 Average 30.89 Standard Deviation 0.31
Gasifier Maintenance
While running the experiments, a number of maintenance issues were encountered. Some components of the gasifier failed and were fixed once, while other problems persisted throughout the run of experiments. Below is a brief summary of the main issues encountered.
Carbon Monoxide . During the initial setup of the Ankur gasifier, many CO leaks were detected. These leaks were detected with a portable CO meter and were all sealed. The greatest leak came from the gas blower, which had to be partially disassembled and re- sealed. After the initial sealing of the leaks, no more CO leaks were detected for the duration of the experiments.
67
Vibrator Motor . A vibrator motor is mounted on the hopper to assist in moving the
fuel through the gasifier. After the first few startup experiments, the vibrator motor’s
mounts completely broke off during operation and an emergency shutdown was required.
The vibrator motor and broken mounts are shown in Figure 4.13. When installed, there is
a metal housing around the vibrator motor so the operators were safe. A custom motor
mount was fabricated for the vibrator motor which performed well for the duration of the
experiments.
Figure 4.13: Vibrator motor and broken mounts.
Wood Level Sensor . The wood level sensor is installed on the hopper. As described in
Chapter 3, when fuel drops below the sensor, it spins freely and activates the empty fuel alarm, which alerts the operators of the need to add more fuel. This sensor failed early on in the experiments and would no longer spin. It was not necessary to repair this sensor because Ankur supplied two sensors with the gasifier. The backup sensor was installed and performed well for the duration of the experiments.
68 Automatic Ash Collection System . The gasifier is equipped with a pneumatic ash
collection system. As described in Chapter 3, the char-ash collects in the bottom of the
reactor. When needed, a pneumatic door is opened to dump the char-ash into a cylinder.
To maintain the partial vacuum in the gasifier, the top pneumatic door is closed first, and
the bottom pneumatic door is opened to release the char-ash from the cylinder.
On several occasions, the char-ash failed to properly fall into the cylinder. The
particles would form a stable matrix above the pneumatic door and would not fall into the
cylinder, as shown in Figure 4.14. To remove the char-ash, the pneumatic door assembly
needed to be completely removed before removing the char ash by hand. For this reason,
it was extremely difficult to quantify char-ash production for each experiment
individually. The 13% MC experiments were conducted first, and the problem was
noticed during this time which is why char-ash production was only reported for the third
13% MC experiment. For the 6% and 22% MC experiments, it was decided to
thoroughly clean out the char-ash collection system after each set of experiments were
completed. Therefore, total char-ash production for each set of experiments was
reported.
69
Figure 4.14: Looking straight up into the bottom of the reactor bed, this image shows that the ash gets clogged before it drops into the automatic ash collection system, which has been moved to the side for manual removal of the ash.
Water Scrubber System . When the product gas exits the gasifier, a water jet both
cools the gas and removes large particulate matter. Severe buildup of tar and particulate
matter was found to occur at this area. The matter would build up around the water jet
system and also on the pipe directly above this. After each experiment, the water jet
assembly needed to be opened and cleaned, Figure 4.15 and Figure 4.16.
70
Figure 4.15: Tar and particulate buildup around and behind water jet in scrubber system.
Figure 4.16: The water jet, pictured above, is installed here in the scrubber system, where more tar and particulate buildup is visible.
71 Also, the water pump for the scrubber system needed maintenance before each experiment. The pump would seize and would not start. Before each experiment, the water pump would have to be opened in order to un-seize it to make the pump turn.
Usually, after manually turning the pump, it would start under its own power. Sometimes however, while the pump was turned on but not rotating, it was necessary to use a screwdriver to manually force the pump to begin rotating. Once the pump could turn on under its own power, it would be sealed and the gasifier startup procedures would continue. After this initial maintenance, the water pump would perform well for the duration of each experiment.
Water Buildup . Water buildup in various components of the gasifier was an issue
for each experiment. First, buildup would occur in the plastic tubing on the digital
differential pressure transducers and would need to be cleaned after each experiment.
This problem led to faulty readings on some of the pressure transducers. The analog
pressure manometers served as a backup and performed well. Second, water
accumulated in the bag filter housing, and needed to be removed after each experiment.
This buildup would eventually flood the bag filter pressure transducer tubing. Third,
water would build up in the hose between the product gas blower and the flare. This
would restrict flow through this pipe and after some time, water droplets could be seen
shooting out of the flare with the flame. This issue was remedied by installing a “T” on
this hose which allowed the water to flow into a second hose, sealed at the other end,
during the experiment. Afterwards, the water would be emptied from the second hose.
72 Paint . The sawdust filter and bag filter assembly, as-received from Ankur, were painted on the inside. Once operation began, the paint began to fall off immediately. This loose paint was removed during post operation maintenance after the first few experiments.
Afterwards, the remaining paint remained adhered to the inner surfaces.
CHAPTER 5. DISCUSSION
In this chapter, the results presented in the previous chapter are discussed further, and are compared to the literature as well as Ankur Scientific’s own claims from the gasifier Operations Manual. Also, a discussion of the gasifier fuel is presented, which includes comments on fuel size and the difference between hardwood and softwood in terms of gasification. Finally, the performance evaluation is presented.
Experimental Run Time
As will be discussed below, most of the performance parameters that were measured are comparable to the literature for other downdraft gasifier experiments that used woody biomass for fuel. However, the experimental run times are relatively short for this set. The average run time for the ten efficiency intervals in this set is only 2.9 hours, with the longest interval being 3.6 hours, from the 2 nd 22% MC experiment.
The short run times were due to reduced gas flow rates caused by tar and particulate buildup in the water scrubber and water buildup in the product gas line between the gas blower and the gas burner. For example, the unprocessed mass flow readings for the 2 nd 22% MC experiment are shown in Figure 5.1. At approximately the two hour point, the nozzle on the gas blower was opened fully to compensate for reduced gas flow, which increased the flow by about 150 SLM. This experiment was terminated at approximately 4.5 hours of total experimental run time due to rapid loss in gas flow, and the increased noise in the data at the end of this experiment is due to water
73 74 accumulation in the orifice plate pressure transducer tubing. Ankur claims a gas flow rate of 880 slm (Table 3.1), but after 4.5 hours of operation, this gasifier was only able to produce product gas at a rate of 400 slm, which is less than 50% of the rating. And at no point during the experiment did the flow rate exceed 650 SLM, which is less than 75% of the rating.
800 700 600 500 400 300
Reading (SLM) 200 100 Raw OrificeRaw PlateFlow 0 0 1 2 3 4 5 Experimental Run Time (Hrs)
Figure 5.1: Unprocessed product gas mass flow readings for the 21.6% MC experiment, the second in the 22% MC set.
Ankur claims “trouble-free service for years” in the Operations Manual for this gasifier, but continuous operation was never sustained for more than 4.75 hours in this set of experiments. If softwood gasification becomes a reality, much longer run times will undoubtedly be required. Sustained operation hinges on controlling blockages to gas flow, which includes controlling tar and particulate accumulation as well as water accumulation throughout the gasifier. In future experiments, it will be essential to determine if softwood gasification can be sustained for many hours.
75 Equivalence Ratio
When moisture content increases in the fuel, more air is needed to drive off the moisture as it diffuses to the boundary layer that forms on the surfaces of the fuel particles. The air creates turbulence and therefore more air is required to dry the wet fuel inside of the gasifier (Miles, 2010). The result is a higher equivalence ratio, or ER. This leads to a higher nitrogen content in the product gas and a lower energy content.
When the ER falls below 0.25, another undesirable effect occurs. When too little oxygen is introduced to the gasifier, some of the char is not converted to gas and the result is a higher percentage of char leaving the gasifier (Reed, 1988). Excess char means that fuel that otherwise could have been converted to combustible gas is not used.
Although the char results of this survey are limited, the 6% MC experiments, which had the lowest ER averaging to 0.231, did produce the most char, Table 4.10.
This set of experiments produced ERs ranging from 0.227 to 0.341, Table 4.2.
This is within the range cited in the literature of 0.21 – 0.38 (Chapter 2). The theoretical
optimal value for this parameter is 0.25 (Reed 1988). The 13% MC set of experiments
produced an average ER of 0.261, the closest to 0.25, and suggests that this MC is
preferred to the 6% and 22% MC fuel.
Gas Composition
The product gas composition for Douglas Fir wood chip fuel in this gasifier was similar to the compositions reported in the literature for other woody biomass fuels, Table
2.2. Across the range of moisture contents studied, the amount of nitrogen, carbon
76 monoxide, carbon dioxide, and methane in the product gas all agreed with the literature.
Hydrogen was the only exception. The literature reports hydrogen values in the range of
14.5% - 22.7% for woody biomass. In this set of experiments, the range of hydrogen was
11.5% - 13.7%, which were all below the expected range. A comparison with Ankur’s expected gas compositions is given in Table 5.1, which also shows that hydrogen was the only gas component that was unexpectedly low.
Table 5.1: Average product gas composition of each set of MC experiments compared with manufacturer’s claims. Ankur 6% MC 13% MC 22% MC Gas Claim* Average Average Average N2 50 46.80 47.95 52.35 H2 18 ± 2 13.37 13.32 12.34 CO 19 ± 3 24.72 22.30 17.78 CO 2 10 ± 3 10.04 11.40 13.30 CH 4 ≤ 3 2.55 2.50 2.06 *Ankur Scientific (2008)
The gas composition did vary as the moisture content of the fuel was varied.
Chee (1987) conducted a moisture content survey on Cottonwood and found that as the fuel becomes more moist, carbon monoxide and nitrogen decrease while hydrogen and carbon dioxide increase. Methane does not appear to be affected by the moisture content of the fuel. In the Douglas Fir survey for this thesis, carbon monoxide decreased and carbon dioxide increased as the fuel increased in moisture. Methane remained mostly unaffected by fuel moisture. This agrees with the Cottonwood survey, but the nitrogen and hydrogen trends do not. Here, nitrogen increased with moisture content which
77 suggests that too much air was being drawn into the gasifier. Hydrogen changed only slightly with moisture content, Figure 4.5. As fuel increases in moisture, more water should be available for the water-shift reaction. For this reason, it was expected that hydrogen would increase with increasing moisture in the fuel like the Cottonwood survey, but instead the highest MC experiments had the lowest hydrogen levels.
The water shift reaction converts carbon monoxide into hydrogen. The fact that hydrogen levels did not increase with MC suggests that this reaction was compromised during the experiments. Also, in the char bed, if the temperature is high enough then the moisture will endothermically react with the carbon in the char to form carbon monoxide and hydrogen via the water gas reaction. This reaction effectively balances the hydrogen and carbon monoxide content of the product gas (Kaupp, 1984). In the 6% MC experiments, carbon monoxide content averaged to 24.7% while hydrogen content averaged to 13.4%. The small size of the fuel may have caused the char particles to be too small to effectively hold enough heat to sustain this reaction, which means that some of the moisture simply passed through the char bed without reacting. Inside the hopper and reactor, a thermocouple was used in this study to monitor the combustion zone temperature only. In future work, if possible, a thermocouple is needed in the char bed.
Energy Content of Product Gas.
For woody biomass in downdraft gasifiers, the literature cites a range of product gas energy contents from 5.0 – 6.3 MJ/m 3, Table 2.3. This set of experiments produced
gas with energy contents ranging from 5.0 – 6.5 MJ/m 3, which agrees very well with the
78 literature. Ankur claims an energy content of 4.18 MJ/m 3 for this gasifier, Table 3.1, but when the average gas composition that Ankur claims is used to calculate energy content, the value is 5.3 MJ/m 3. In this case, the results exceeded the manufacturer’s claims. The energy content drops as the fuel increases in MC. The decrease in energy content is due primarily to the decrease in carbon monoxide, as shown in Figure 5.2, because the level of the combustible gas methane did not significantly change across MC, and the level of combustible gas hydrogen changed only slightly. On average, the 6% and 13% MC fuel produced product gas with 26% and 20% more energy than the 22% MC fuel, respectively, which suggests that 22% MC is too high for effective gasification.
7
6 22% MC 13% MC 6% MC 5
4
3 y = 0.1966x + 1.6388 Gas (MJ/m^3) 2 R2 = 0.9716 1
Total Energy Content of Product 0 15 17 19 21 23 25 27 Carbon Monoxide in Product Gas (%)
Figure 5.2: Product gas energy content vs. carbon monoxide content.
Fuel Consumption Rate
The average fuel consumption rate for the 6% and 13% MC experiments were greater than Ankur’s claims, as shown in Table 5.2. This increased consumption rate was
79 most likely caused by the small particle size of the fuel, which allowed it to break down faster than larger diameter fuel. The decrease in fuel consumption as MC increased was most likely due to the need for the fuel to dry before it pyrolysed and broke down into combustible gas. More air and thus more time were needed for this.
Table 5.2: Average dry fuel consumption compared to manufacturer’s claim (kg/hr). Ankur 6% MC 13% MC 22% MC rating* Average Average Average 13-15 20.7 18.5 14.3 *Ankur Scientific (2008)
Cold Gas Efficiency
Across the range of moisture contents studied, the cold gas efficiency remained relatively stable, remaining within 3% of the average of 65.7%. The Cottonwood survey by Chee (1987) also resulted in a flat efficiency curve, but the efficiency was an average of 69%. This suggests that softwood is less efficient than hardwood. The results of this survey are comparable to the reported cold gas efficiencies for various species of wood in downdraft gasifiers, which range from 57% - 81%, as was shown in Table 2.4. The
Operations Manual for the Ankur gasifier used in this set of experiments states that the efficiency is greater than 75%, which is 9% higher than the results of this survey.
Even though the energy content of the product gas increased as the moisture content of the fuel decreased, the efficiency curve was still flat. This increase in product gas energy content was also accompanied by an increase in dry fuel consumption, as shown in
Figure 5.3. The increased fuel consumption meant that more energy was contained in the
80 input fuel because more dry fuel was gasified in the same amount of time as fuel with more moisture. This effect appeared to cancel out the increase in product gas energy content, leading to a relatively flat efficiency curve across the range of moisture contents studied. Also, Ptasinski (2006) presents theoretical efficiency curves that flatten out when biomass drops below 20% MC, as was shown in Figure 2.7. The curves still increase as the fuel becomes drier, but there is a sharp change in slope around 20% MC.
7
6
5
4 y = 0.1864x + 2.5596 3 2
(MJ/m^3) R = 0.8245 2
1
Product Gas Energy Content 0 10 15 20 25 Dry Fuel Consumption Rate (kg/hr)
Figure 5.3: Product gas energy content vs. dry fuel consumption rate.
Energy can also be lost when un-reacted fuel exits the gasifier as char-ash. In addition to the higher energy product gas/higher fuel consumption correlation described above, there also appears to be a connection between average efficiency and char-ash production, as shown in Figure 5.4.
81
100% 90% 80% 22% MC 70% 60% 50% 13% MC 6% MC 40% 30% y = -0.9132x + 0.7073 20% R2 = 0.8058 10% 0% Average Cold Gas Efficiency (%) Efficiency Gas Cold Average 0% 2% 4% 6% 8% Char-Ash Production (% of Dry Fuel Gasified)
Figure 5.4: Average cold gas efficiency vs. char-ash production.
Thermal Power
The thermal power for both the 6% and 13% MC experiments were in the 65 – 80 kilowatt thermal, kWth, range. The thermal power for the 22% fuel was in the 45 – 60 kWth range, however. Like the other performance indicators, this is further evidence that
22% MC wood has too much moisture for effective gasification. For this gasifier,
Ankur’s rating is 11 kWe but no rating is given for running the gasifier in thermal mode only.
Tars and Particulates
For this set of experiments, the tar measurements have the largest variability. The glass micro fiber mass difference approach to measure this parameter needs to be improved for future experiments. Also, the values reported are the total tars and
82 particulates contained in the filtered product gas. In the future, these two types of impurities need to be separated. The large range of values could also be attributed to transient processes in the gasifier. For example, the effectiveness of the sawdust filter can change after it has been stirred as well as after it has begun to accumulate tar and particulate matter.
When looking at the average tar/particulate values for each MC set of experiments, it appears that the gas becomes cleaner as the fuel MC increases. The average tar/particulate values for the 6%, 13%, and 22% MC experiments are 740, 620, and 400 mg/m 3, respectively. This range of tars is comparable to other downdraft
gasifiers. Reed (1988) reports tar measurements from various downdraft gasifiers in the
range of 500 – 3000 mg/Nm 3. Other claims are much lower, however. For example,
Schmidt (2000) claims that Ankur gasifiers, one of which was used for this experiment, generate a product gas with less than 5 mg/Nm 3 of tars. This value does not include
particulate matter, however.
Douglas Fir Woodchips as Fuel
This thesis was performed in order to evaluate the performance of a small scale downdraft gasifier by varying the moisture content of softwood fuel. Non-uniform softwood Douglas Fir wood chips were chosen as the fuel in order to simulate and study the efficacy of using gasifiers to convert sustainably harvested forest biomass, as well as recovered biomass from timber harvest sites, into electricity in the western US where softwood is dominant. Tom Miles, a leading expert on the subject of small scale
83 downdraft gasification and administrator of the Gasification Digest email listserve, provided key insights on fuel size and the difference between hardwood and softwood.
First, hardwood and softwood can be classified as a surface reactor and an internal reactor, respectively. When hardwood becomes char in a gasifier, its density and morphology allow it to be reduced by CO 2 reacting with the surface of the char particles.
The hardwood char pieces hold together and are consumed from the outside in, in the
reduction zone. Conversely, softwood char will crack, split, and fissure along structural
discontinuities within the fuel, becoming more like popcorn, generating fine particles.
Also, the lower density of softwood makes it decompose more quickly (Miles, 2010).
This is why, historically, hardwood has been the fuel of choice for downdraft biomass
gasifiers.
Second, the size and geometry of the fuel is as important as the design of the gasifier itself. Disc chippers make wood chips that are approximately ⅛ – ¼ in. thick, which is the thickness of the wood chips used in this thesis. The thickness of the chips is the critical property when it comes to pyrolysis, combustion, and gasification. Inside of a gasifier, thin chips heat up and de-volatilize faster than thick chips, which results in smaller char particles. These small char particles are harder to draw gas from because they have low porosity. For good downdraft gasification, the wood chips need to be at least ¾ in. thick (Miles, 2010).
Third, tar production increases with small particle wood fuel. In the combustion zone, wood first becomes hot and de-volatilizes which releases the tars. Then after the tars are released, they are burned. Thick blocky fuel provides favorable radiating
84 surfaces as these hot surfaces create turbulence with high velocity air jets which aid in the combustion of tars. Fine fuels generate more tar which will have to be removed at the scrubber if it isn’t combusted before the reduction zone (Miles, 2010). The non- uniformity and small particle size fuel may have led to non-uniform temperature distributions in the combustion zone which could allow un-combusted tars to pass through the throat of the hopper.
Using small, thin softwood fuel therefore leads to two issues. First, more tars are generated and second, the small char particles create an unfavorable char bed. A bed of chunky char is more porous and allows the CO 2 to more easily react with the carbon in
the char and reduce it to CO and H 2, which is the desired result.
Performance Evaluation
The Ankur WBG20 downdraft gasifier was evaluated by using non-uniform softwood Douglas Fir woodchips over a moisture content range of 6% to 22%. Based on the overall results, the 13% MC fuel performed the best. The equivalence ratio at this
MC was closest to the theoretical optimal value of 0.25, the least amount of char was produced, and, although the efficiency curve was virtually flat across all experiments, the
13% MC experiments produced the highest efficiencies of the survey by a small margin.
The 13% MC average efficiency was 67.5% while the 6% and 22% MC average efficiencies were 64.3% and 64.7%, respectively.
85 The 6% MC fuel produced product gas with the highest energy content (6.42
MJ/m 3), but this was accompanied by the highest dry fuel consumption rate (20.7 kg/hr).
The result was a slightly lower efficiency than the 13% MC fuel. Also, the 6% MC fuel
produced the highest amount of char-ash, which also contributed to the lower efficiency
compared to the 13% MC fuel.
The 22% MC fuel produced product gas with the lowest energy content (5.09
MJ/m 3). Also, this set of experiments produced the lowest dry fuel consumption rate
(14.3 kg/hr), the lowest product gas hydrogen content (12.3%), and the lowest output power (average of 52 kWth). These results support Ankur’s claim that fuel needs to be below 20% MC for effective gasification. The remainder of this section will focus on the results of the 13% MC set of experiments.
When looking at equivalence ratio, product gas composition, and product gas energy content, the Ankur WBG20 downdraft gasifier performed well, as these values were typical of other woody biomass downdraft gasification experiments. Although the hydrogen content was low, and below Ankur’s claim, from an energy standpoint this was compensated for by high carbon monoxide content.
Ankur claims that the efficiency of the WBG20 downdraft gasifier is greater than
75%. Although the 13% MC efficiency was nearly 7% below this value, the 67.5% result is well within the range of reported efficiencies. As reported in Table 2.4, Rajvanshi
(1986) states that, in general, wood fuel is 60-70% efficient in downdraft gasifiers.
Compared to Ankur’s claim, the result is low, but compared to other experiments, the result is typical.
86 The tar and particulate matter in the filtered product gas appears to be typical of downdraft gasifiers (Reed, 1988). However, without knowing the fraction of the matter that was tars, and the fraction that was particulates, it is difficult to determine how the results actually compare to the literature. The variability in these data were a problem in this survey, and need to be improved for future experiments.
The high fuel consumption rate, high char-ash production, some of the maintenance issues, and the short experimental run times may very well be attributed to the geometry of the fuel and not to the Ankur WBG20 gasifier itself. As mentioned in the previous section, the small thin woodchips used in this survey were not the fuel that this gasifier was designed to handle, in terms of shape and size. The small particles may have simply moved through the gasifier too quickly, leading to the high fuel consumption rates. Also, the char-ash production could have been high because too many small char particles fell through the grate at the bottom of the reactor before fully reacting, which led to the char-ash collection system becoming clogged on a regular basis. Furthermore, the small fuel size may have produced an extreme amount of tars and particulate matter, more than this gasifier was designed to handle. This may very well be the reason that the scrubber system became so quickly clogged, leading to a decrease in gas flow and helping to cause the short run times. Excessive particulate matter, from too much fine char particles, may have been the reason that the water scrubber pump motor needed to be manually started so frequently.
There were other operational issues that were not related to fuel size and shape, however. First, the vibrator motor broke off of the gasifier after only a few hours of
87 operation, and, although the custom made replacement motor mount performed well for the duration of the experiments, such failures have the potential to be a safety hazard for the operator. Second, the experimental run times were cut short due to excessive water buildup in the product gas lines and filter housings. Even if moisture did not fully react with carbon in the char bed to form more H 2 and CO, any excess moisture in the product
gas would be equalized at the point of the water scrubber system.
In summary, when using non-uniform, thin Douglas Fir woodchips in an Ankur
WBG20 downdraft gasifier, the short term performance was good, but the long term
performance was poor. The poor long term performance may very well be a fuel issue
and not a gasifier issue. Regardless of the reason, thin softwood wood chips are not
recommended for sustained long term use. Finally, regarding moisture content, it is not
necessary to consume energy drying fuel down to 6% MC, as 13% MC is dry enough for
effective gasification.
CHAPTER 6. CONCLUSIONS AND RECOMMENDATIONS
Although softwood gasification is possible, much work remains to be conducted if small scale decentralized gasification is to become a realistic source for electricity generation in the western US. In this survey, most of the performance parameters agreed with previous hardwood studies in the literature, but the experiments conducted for this thesis were relatively short. The most important issues to be resolved are fuel preparation and product gas filtration.
The fuel used in these experiments was non-uniform in size and thin.
Historically, downdraft gasification has worked best with uniform two inch hardwood cubes. In order to effectively gasify the vast amounts of softwood biomass available in the western US in the form of forest residues from logging and forest thinning operations, a processing method for generating a uniform and thicker sized fuel size is needed.
In general, woody biomass fuel is prepared for gasification by either chipping or
densifying the fuel. It is clear from the results of this thesis that the standard disc
chippers produce fuel that is too small and too thin for long term softwood gasification.
There are chippers, however, that are designed to generate larger and thicker woodchips.
One example is the Laimet HP-25 screw auger chipper (Laimet 2010). This chipper
produces larger and thicker chips than a standard disc chipper, but the particle size is still
non-uniform. To generate uniformly sized biomass fuel, the fuel can be densified into
pellets or briquettes. The tradeoff of densification is that it is logistically more difficult
than simply chipping the fuel, and the original structure of the fuel is lost. Softwood
88 89 pellets or briquettes might break down easier than thick chips, which would lead to the same issues encountered in this study.
Therefore, a recommendation for further work with the Ankur WBG20 downdraft gasifier is to investigate performance with softwood fuel by using thicker woodchips as well as densified fuel. Although clean chips were used as fuel for this thesis, in reality the potential stock of biomass in the form of forest residues will be heterogeneous in nature and include bark, twigs, and leaves. For this reason, densification of actual forest residues into a uniform particle size should be investigated.
Fuel moisture content is also critical in fuel processing and fuel preparation. The
results presented here agree with the general rule that biomass needs to be less than 20%
MC in order to be effectively gasified. Gasifier performance with 22% MC fuel was poor
compared to the 6% and 13% MC fuel in terms of product gas energy content, fuel
consumption, and output power. On the other hand, the 6% MC fuel performance was
comparable to the 13% MC fuel in terms of efficiency and output power. This suggests
that energy does not need to be wasted in drying fuel down to 6%. A drying method to
produce fuel near 13% appears adequate. In future work, the moisture should be held
constant while fuel size is varied.
The filtration and cleanup method for the product gas is also a critical task that
needs to be resolved. On this Ankur gasifier, a water scrubber system was used, but the
water was not deemed to be a hazardous material. However, the used sawdust and bag
filters were deemed hazardous. The accumulation of hazardous waste will present a
90 problem in the future if small scale downdraft gasification becomes an actual method to convert biomass into usable energy on a large scale.
There are more effective gas filtration methods available now, but they are very expensive. The main competitor to Ankur in the small scale downdraft gasifier market is
Community Power Corporation, CPC. CPC’s BioMax line of gasifiers are commercially available. Their cleanup system uses no water, and no hazardous materials are generated.
The tradeoff is the cost. The Ankur gasifier used in this study cost about $30,000 while a comparable CPC BioMax 25 kWe system is $180,000 to over $250,000 (Walt 2009).
A theoretical study was conducted which used CPC gasifiers to test the logistical and economical feasibility of decentralized gasification at forest landings in southern
Oregon (Bilek 2005). A 100 kWe and a 1000 kWe system were modeled. At the 100 kWe scale, gasification would not be economical without tax credits and subsidies. Also, the fuel delivered to the gasifier would have to be free. At the 1000 kWe scale, it would be economical with a tax credit but only if merchantable timber could also be sold in conjunction with the biomass gasification. The current tradeoff to a cleaner filtration system is the cost of the equipment.
In addition to the commercially available CPC Biomax gasifiers, there is an experimental gasification project currently in progress in California which is also using a dry gas cleaning method with no water or sawdust filters. This experimental gasifier is a
Californian MK5 Andes Class gasifier and has a capacity of 100 kWe (Fluidyne 2010).
The research team is also using the Laimet HP-25 screw auger chipper to generate thicker chips. Since this project is in the research phase, the cost of the system is not available.
91 For future work, dry gas cleaning methods which use hot gas filters should be investigated in order to minimize the accumulation of hazardous waste.
Theoretically, it appears possible to displace 30% of US petroleum use with sustainably harvested timber and forest residues by using decentralized gasification
(Perlack et. al., 2005). However, most gasification studies in the literature use hardwood as a fuel source while a majority of the biomass resource in the US is in fact softwood.
The main result of this thesis is that small, thin, non-uniform softwood chips are not the correct fuel size to use to try to meet the theoretical goal. However, softwood should still be further investigated as the Ankur WBG20 did in fact produce typical product gas, albeit for a short time. Clearly, further research on softwood gasification requires a study focusing on both fuel size and uniformity of fuel size.
REFERENCES
Adams, Darious M., Haynes, Richard W., Daigneault, Adam J., 2006. “Estimated Timber Harvest by U.S. Region and Ownership, 1950-2002” United States Department of Agriculture Forest Service, Pacific Northwest Research Station, General Technical Report PNW-GTR-659, January 2006.
Ankur Scientific, 2008. “Ankur Biomass Gasifier (Model WBG-20) Based Power Generating Set in 100% Gas Mode” Operation Manual.
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APPENDIX A
A.1 Run Summary for 5.7% Moisture Content Run
Table A.1.1 Cold gas efficiency determination for 5.7% MC run during efficiency interval. Efficiency Interval (hours) 2.17 Total Product Gas Flow in Efficiency Interval (SL) 96,673 Total Energy in Product Gas in Efficiency Interval (MJ) 620.42 Total Wet Fuel Gasified in Run (kg) 72.2 Average Fuel Moisture Content for Run, wet basis (%) 5.7 Total Dry Fuel Gasified in Run (kg) 68.05 Total Dry Fuel Gasified in Efficiency Interval (kg) 46.64 Total Energy in Fuel in Efficiency Interval (MJ) 940.3 Cold Gas Efficiency (%) 66.0
Table A.1.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 5.7% MC Run. Total Nitrogen Flow in Product Gas (SL) 45,169 Total Air Entering Gasifier (SL) 57,847 Total Air Entering Gasifier (kg) 69.42 Total Dry Fuel Gasified (kg) 46.64 Air-Fuel Ratio (kg air/kg fuel) 1.49 Air-Fuel Ratio for Complete Combustion 6.29 Equivalence Ratio ( Air-Fuel Ratio / Air-Fuel for 0.237 Complete Combustion)
Table A.1.3 Tar and particulate measurements for 5.7% MC run. Product Gas Flow Filter Mass Difference Tar and Particulate Filter Through Filter after 24 hr. in Matter in Product (SL) Dessicator (mg) Gas (mg/m 3) 1 60.76 33.0 543 2 54.79 46.5 849
95 96 Table A.1.4 Processed data for each GC interval for 5.7% MC run. Product Gas Ave. Product Gas Gas Flow Total Energy Total Gas Injection Time Temperature HHV In Interval Correction in Product Flow (SL) (°C) (MJ/SL) X 10 3 Factor Gas (MJ) 4/24/2009 12:55 20.03 1.058 4/24/2009 13:00 22.27 6.08 1.064 3,808 23.14 4/24/2009 13:05 23.60 6.33 1.072 3,827 24.21 4/24/2009 13:10 24.44 6.30 1.071 3,820 24.07 4/24/2009 13:15 25.30 6.53 1.085 3,773 24.63 4/24/2009 13:20 26.19 6.43 1.076 3,821 24.56 4/24/2009 13:25 27.16 6.24 1.081 3,757 23.45 4/24/2009 13:30 27.90 6.50 1.086 3,741 24.31 4/24/2009 13:35 28.56 6.30 1.078 3,720 23.42 4/24/2009 13:40 29.57 6.10 1.081 3,671 22.39 4/24/2009 13:45 30.26 6.23 1.083 3,663 22.82 4/24/2009 13:50 31.15 6.35 1.085 3,656 23.20 4/24/2009 13:55 31.57 6.42 1.094 3,640 23.37 4/24/2009 14:00 32.05 6.46 1.087 3,702 23.92 4/24/2009 14:05 31.76 6.49 1.087 3,729 24.19 4/24/2009 14:10 32.22 6.52 1.088 3,656 23.85 4/24/2009 14:15 32.32 6.46 1.089 3,680 23.76 4/24/2009 14:20 33.17 6.28 1.088 3,706 23.27 4/24/2009 14:25 34.44 6.31 1.090 3,708 23.39 4/24/2009 14:30 34.99 6.60 1.103 3,635 23.99 4/24/2009 14:35 35.30 6.73 1.102 3,700 24.89 4/24/2009 14:40 35.50 6.58 1.094 3,749 24.66 4/24/2009 14:45 35.85 6.44 1.093 3,759 24.20 4/24/2009 14:50 35.93 6.49 1.099 3,719 24.13 4/24/2009 14:55 36.26 6.56 1.093 3,677 24.12 4/24/2009 15:00 36.29 6.58 1.099 3,708 24.42 4/24/2009 15:05 36.72 6.59 1.099 3,649 24.06
97 Table A.1.5 Unprocessed GC gas composition for 5.7% MC run (mole percent).
Injection Time H2 O2 N2 CH 4 CO CO 2 C2H4 C2H6 C2H2 4/24/2009 12:55 13.56 0.31 49.72 2.42 20.64 12.05 0.61 0.07 0.16 4/24/2009 13:00 13.49 0.33 48.16 2.55 22.80 11.44 0.66 0.08 0.19 4/24/2009 13:05 14.13 0.29 47.69 2.61 23.00 10.87 0.71 0.07 0.16 4/24/2009 13:10 13.56 0.30 48.03 2.17 24.42 10.41 0.55 0.06 0.17 4/24/2009 13:15 15.26 0.00 45.42 3.05 24.40 10.02 0.74 0.09 0.17 4/24/2009 13:20 13.67 0.00 48.50 1.93 24.52 9.92 0.48 0.05 0.16 4/24/2009 13:25 14.18 0.23 46.77 2.44 24.78 10.18 0.61 0.07 0.17 4/24/2009 13:30 14.41 0.00 46.43 2.51 25.29 9.63 0.60 0.07 0.16 4/24/2009 13:35 13.09 0.00 48.97 2.18 24.35 9.88 0.56 0.07 0.17 4/24/2009 13:40 13.42 0.00 48.18 2.17 24.70 10.01 0.53 0.06 0.16 4/24/2009 13:45 13.28 0.00 47.28 2.23 26.02 9.61 0.57 0.08 0.16 4/24/2009 13:50 13.64 0.00 47.26 2.45 24.73 10.25 0.64 0.08 0.19 4/24/2009 13:55 14.48 0.00 46.67 2.39 25.41 9.32 0.59 0.07 0.16 4/24/2009 14:00 13.51 0.00 46.83 2.51 25.37 10.00 0.63 0.09 0.18 4/24/2009 14:05 13.39 0.57 47.39 2.50 24.80 9.91 0.65 0.09 0.18 4/24/2009 14:10 13.24 0.65 47.74 2.56 24.45 9.90 0.66 0.09 0.17 4/24/2009 14:15 13.17 0.64 48.69 2.45 24.11 9.43 0.63 0.08 0.16 4/24/2009 14:20 13.13 0.00 48.16 2.05 25.89 9.41 0.52 0.07 0.16 4/24/2009 14:25 12.94 0.00 47.10 2.37 26.58 9.49 0.62 0.09 0.20 4/24/2009 14:30 14.58 0.00 46.30 2.83 25.77 8.99 0.68 0.09 0.15 4/24/2009 14:35 14.10 0.22 46.81 2.60 26.36 8.56 0.63 0.08 0.16 4/24/2009 14:40 13.28 0.19 47.33 2.46 25.62 9.66 0.61 0.09 0.18 4/24/2009 14:45 13.22 0.00 47.06 2.49 25.77 9.98 0.65 0.09 0.18 4/24/2009 14:50 13.96 0.00 46.85 2.65 25.57 9.52 0.65 0.08 0.17 4/24/2009 14:55 13.67 0.00 46.30 2.92 24.36 11.01 0.77 0.11 0.18 4/24/2009 15:00 14.24 0.00 45.86 2.72 25.11 10.15 0.68 0.09 0.15 4/24/2009 15:05 13.41 0.39 47.16 2.51 25.93 9.06 0.63 0.09 0.16
98 A.2 Run Summary for 5.8% Moisture Content Run
Table A.2.1 Cold gas efficiency determination for 5.8% MC run during efficiency interval. Efficiency Interval (hours) 2.50 Total Product Gas Flow in Efficiency Interval (SL) 101,436 Total Energy in Product Gas in Efficiency Interval (MJ) 656.07 Total Wet Fuel Gasified in Run (kg) 73.2 Average Fuel Moisture Content for Run, wet basis (%) 5.8 Total Dry Fuel Gasified in Run (kg) 69.00 Total Dry Fuel Gasified in Efficiency Interval (kg) 51.00 Total Energy in Fuel in Efficiency Interval (MJ) 1,028.2 Cold Gas Efficiency (%) 63.8
Table A.2.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 5.8% MC run. Total Nitrogen Flow in Product Gas (SL) 47,357 Total Air Entering Gasifier (SL) 60,649 Total Air Entering Gasifier (kg) 72.78 Total Dry Fuel Gasified (kg) 51.00 Air-Fuel Ratio (kg air/kg fuel) 1.43 Air-Fuel Ratio for Complete Combustion 6.29 Equivalence Ratio ( Air-Fuel Ratio / Air-Fuel for 0.227 Complete Combustion)
Table A.2.3 Tar and particulate measurements for 5.8% MC run. Product Gas Filter Mass Tar and Particulate Filter Flow Through Difference after 24 Matter in Product Filter (SL) hr. in Dessicator (mg) Gas (mg/m 3) 1 32.57 29.0 890 2 32.72 21.1 645 3 26.60 19.5 733 4 26.50 12.1 455
99 Table A.2.4 Processed data for each GC interval for 5.8% MC run. Product Gas Ave. Product Gas Gas Flow Total Energy Total Gas Injection Time Temperature HHV In Interval Correction in Product Flow (SL) (°C) (MJ/SL) X 10 3 Factor Gas (MJ) 4/29/2009 12:00 19.06 1.057 4/29/2009 12:05 20.86 6.23 1.061 3,383 21.07 4/29/2009 12:10 22.47 6.30 1.067 3,403 21.43 4/29/2009 12:15 23.53 6.36 1.070 3,417 21.73 4/29/2009 12:20 24.22 6.37 1.072 3,412 21.73 4/29/2009 12:25 25.29 6.41 1.072 3,455 22.14 4/29/2009 12:30 26.50 6.47 1.073 3,459 22.40 4/29/2009 12:35 27.55 6.45 1.079 3,485 22.48 4/29/2009 12:40 28.43 6.41 1.082 3,492 22.40 4/29/2009 12:45 29.37 6.53 1.081 3,467 22.63 4/29/2009 12:50 30.75 6.53 1.077 3,411 22.29 4/29/2009 12:55 31.79 6.80 1.090 3,416 23.24 4/29/2009 13:00 32.44 6.81 1.089 3,451 23.50 4/29/2009 13:05 32.75 6.43 1.089 3,417 21.97 4/29/2009 13:10 32.93 6.49 1.088 3,387 21.98 4/29/2009 13:15 33.67 6.42 1.088 3,360 21.58 4/29/2009 13:20 34.08 6.36 1.090 3,301 20.99 4/29/2009 13:25 33.65 6.54 1.096 3,316 21.69 4/29/2009 13:30 35.17 6.63 1.097 3,336 22.12 4/29/2009 13:35 35.33 6.56 1.094 3,322 21.77 4/29/2009 13:40 36.20 6.41 1.097 3,322 21.31 4/29/2009 13:45 36.95 6.50 1.095 3,325 21.60 4/29/2009 13:50 37.69 6.65 1.098 3,397 22.57 4/29/2009 13:55 37.65 6.62 1.102 3,397 22.50 4/29/2009 14:00 38.66 6.47 1.098 3,451 22.33 4/29/2009 14:05 38.41 6.41 1.103 3,460 22.18 4/29/2009 14:10 38.07 6.50 1.094 3,378 21.96 4/29/2009 14:15 38.74 6.51 1.099 3,256 21.21 4/29/2009 14:20 41.08 6.47 1.094 3,185 20.62 4/29/2009 14:25 41.54 6.16 1.095 3,287 20.26 4/29/2009 14:30 42.28 6.20 1.106 3,291 20.41
100 Table A.2.5 Unprocessed GC gas composition for 5.8% MC run (mole percent).
Injection Time H2 O2 N2 CH 4 CO CO 2 C2H4 C2H6 C2H2 4/29/2009 12:00 12.84 0.32 48.91 2.40 23.83 10.58 0.61 0.09 0.20 4/29/2009 12:05 12.72 0.19 48.61 2.06 25.98 9.30 0.53 0.07 0.17 4/29/2009 12:10 13.16 0.21 47.93 2.27 25.64 9.53 0.58 0.08 0.17 4/29/2009 12:15 13.27 0.29 48.46 2.35 24.79 9.66 0.62 0.07 0.19 4/29/2009 12:20 13.15 0.52 48.49 2.38 24.62 9.59 0.60 0.07 0.17 4/29/2009 12:25 12.71 0.63 48.60 2.34 25.19 9.29 0.61 0.08 0.17 4/29/2009 12:30 12.76 0.80 48.42 2.65 23.64 10.26 0.74 0.10 0.18 4/29/2009 12:35 13.14 0.34 48.52 2.32 25.25 9.12 0.61 0.07 0.18 4/29/2009 12:40 13.32 0.32 47.56 2.23 26.01 9.10 0.58 0.07 0.18 4/29/2009 12:45 13.32 0.33 47.53 2.85 24.07 10.34 0.79 0.10 0.21 4/29/2009 12:50 12.26 0.33 48.23 2.63 25.13 10.00 0.71 0.10 0.21 4/29/2009 12:55 14.17 0.34 45.14 3.61 24.10 10.93 0.97 0.14 0.18 4/29/2009 13:00 13.66 0.31 47.33 2.46 25.15 9.77 0.63 0.08 0.16 4/29/2009 13:05 13.61 0.60 47.95 2.46 23.83 10.27 0.64 0.08 0.15 4/29/2009 13:10 13.57 0.25 46.56 2.74 24.86 10.56 0.72 0.10 0.18 4/29/2009 13:15 12.93 0.36 48.67 2.20 25.19 9.39 0.58 0.08 0.16 4/29/2009 13:20 12.98 0.66 48.30 2.46 24.63 9.62 0.65 0.09 0.19 4/29/2009 13:25 13.31 1.17 48.40 2.53 24.28 8.88 0.62 0.09 0.14 4/29/2009 13:30 14.17 0.00 46.48 2.73 25.81 9.45 0.67 0.09 0.15 4/29/2009 13:35 13.79 0.26 46.95 2.53 24.83 10.30 0.65 0.09 0.17 4/29/2009 13:40 13.68 0.31 47.82 2.27 25.43 9.37 0.56 0.07 0.15 4/29/2009 13:45 13.01 0.30 46.89 2.67 26.05 9.68 0.71 0.10 0.17 4/29/2009 13:50 13.10 0.27 47.16 2.77 25.92 9.43 0.71 0.10 0.17 4/29/2009 13:55 13.82 0.23 46.81 2.63 25.52 9.52 0.64 0.09 0.18 4/29/2009 14:00 12.69 0.83 48.96 2.29 24.81 9.17 0.58 0.08 0.16 4/29/2009 14:05 13.42 0.93 48.84 2.63 23.30 9.46 0.64 0.08 0.18 4/29/2009 14:10 11.71 1.50 49.35 2.42 24.45 9.24 0.65 0.10 0.17 4/29/2009 14:15 11.95 2.00 50.42 2.36 23.07 8.60 0.61 0.09 0.17 4/29/2009 14:20 12.02 0.00 47.31 2.69 26.02 10.14 0.72 0.11 0.18 4/29/2009 14:25 12.64 0.19 49.76 2.40 22.21 11.37 0.60 0.08 0.17 4/29/2009 14:30 13.43 0.21 47.16 2.71 25.06 9.93 0.69 0.09 0.19
101 A.3 Run Summary for 5.5% Moisture Content Run
Table A.3.1 Cold gas efficiency determination for 5.5% MC run during efficiency interval. Efficiency Interval (hours) 2.83 Total Product Gas Flow in Efficiency Interval (SL) 114,138 Total Energy in Product Gas in Efficiency Interval (MJ) 729.51 Total Wet Fuel Gasified in Run (kg) 72.2 Average Fuel Moisture Content for Run, wet basis (%) 5.5 Total Dry Fuel Gasified in Run (kg) 68.22 Total Dry Fuel Gasified in Efficiency Interval (kg) 57.46 Total Energy in Fuel in Efficiency Interval (MJ) 1,158.4 Cold Gas Efficiency (%) 63.0
Table A.3.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 5.5% MC run. Total Nitrogen Flow in Product Gas (SL) 53,641 Total Air Entering Gasifier (SL) 68,696 Total Air Entering Gasifier (kg) 82.44 Total Dry Fuel Gasified (kg) 57.46 Air-Fuel Ratio (kg air/kg fuel) 1.43 Air-Fuel Ratio for Complete Combustion 6.29 Equivalence Ratio ( Air-Fuel Ratio / Air-Fuel for 0.228 Complete Combustion)
Table A.3.3 Tar and particulate measurements for 5.5% MC run. Product Gas Filter Mass Tar and Particulate Filter Flow Through Difference after 24 Matter in Product Gas Filter (SL) hr. in Dessicator (mg) (mg/m 3) 1 27.95 27.2 973 2 29.99 22.4 747 3 25.84 17.8 689 4 20.87 21.8 844
102 Table A.3.4 Processed data for each GC interval for 5.5% MC run. Product Gas Ave. Product Gas Gas Flow Total Energy Total Gas Injection Time Temperature HHV In Interval Correction in Product Flow (SL) (°C) (MJ/SL) X 10 3 Factor Gas (MJ) 5/7/2009 12:00 18.07 1.049 5/7/2009 12:05 19.89 6.10 1.054 3,193 19.49 5/7/2009 12:10 22.04 6.07 1.060 3,301 20.03 5/7/2009 12:15 24.38 6.13 1.067 3,303 20.24 5/7/2009 12:20 26.04 6.41 1.068 3,315 21.25 5/7/2009 12:25 26.8 6.54 1.071 3,317 21.70 5/7/2009 12:30 27.8 6.42 1.074 3,320 21.31 5/7/2009 12:35 29.07 6.45 1.082 3,333 21.51 5/7/2009 12:40 30.52 6.44 1.080 3,327 21.42 5/7/2009 12:45 31.88 6.41 1.082 3,411 21.88 5/7/2009 12:50 33.14 6.49 1.086 3,443 22.35 5/7/2009 12:55 34.35 6.09 1.079 3,420 20.82 5/7/2009 13:00 35.61 5.96 1.088 3,349 19.95 5/7/2009 13:05 36.5 6.16 1.091 3,366 20.73 5/7/2009 13:10 36.36 6.33 1.090 3,374 21.35 5/7/2009 13:15 37.54 6.48 1.099 3,415 22.14 5/7/2009 13:20 37.56 6.69 1.101 3,423 22.90 5/7/2009 13:25 37.91 6.71 1.096 3,393 22.78 5/7/2009 13:35 40.03 6.37 1.101 6,649 42.36 5/7/2009 13:40 40.54 6.50 1.103 3,401 22.12 5/7/2009 13:45 41.68 6.57 1.102 3,391 22.26 5/7/2009 13:50 42.1 6.19 1.096 3,403 21.05 5/7/2009 13:55 42 6.31 1.110 3,395 21.42 5/7/2009 14:00 42.67 6.54 1.105 3,443 22.51 5/7/2009 14:05 43.01 6.48 1.114 3,420 22.15 5/7/2009 14:10 43.75 6.51 1.112 3,445 22.42 5/7/2009 14:20 45.13 6.52 1.110 6,664 43.47 5/7/2009 14:25 45.29 6.40 1.107 3,293 21.08 5/7/2009 14:30 45.62 6.26 1.112 3,311 20.72 5/7/2009 14:35 44.91 6.27 1.113 3,319 20.81 5/7/2009 14:40 45.35 6.36 1.112 3,343 21.26 5/7/2009 14:45 45.88 6.64 1.111 3,319 22.04 5/7/2009 14:50 46.14 6.58 1.110 3,336 21.96
103 Table A.3.5 Unprocessed GC gas composition for 5.5% MC run (mole percent).
Injection Time H2 O2 N2 CH 4 CO CO 2 C2H4 C2H6 C2H2 5/7/2009 12:00 11.74 0.21 49.52 2.31 23.91 10.68 0.66 0.08 0.28 5/7/2009 12:05 12.00 0.24 49.56 2.12 24.65 10.01 0.57 0.08 0.21 5/7/2009 12:10 12.78 0.00 49.23 2.33 23.35 10.54 0.60 0.07 0.21 5/7/2009 12:15 12.88 0.00 48.81 2.44 24.07 9.92 0.61 0.07 0.19 5/7/2009 12:20 12.78 0.00 46.62 2.98 24.43 11.00 0.83 0.12 0.23 5/7/2009 12:25 12.57 0.63 48.29 2.68 23.54 10.55 0.75 0.09 0.19 5/7/2009 12:30 12.57 0.35 48.52 2.50 24.52 9.85 0.68 0.08 0.21 5/7/2009 12:35 13.68 0.29 47.10 2.59 24.63 10.01 0.66 0.08 0.20 5/7/2009 12:40 12.87 0.00 47.77 2.46 25.13 9.84 0.64 0.09 0.20 5/7/2009 12:45 12.87 0.00 47.41 2.81 24.54 10.35 0.76 0.10 0.19 5/7/2009 12:50 13.35 0.00 46.96 2.92 23.78 10.80 0.75 0.11 0.20 5/7/2009 12:55 12.73 0.00 50.27 2.27 20.86 12.03 0.62 0.08 0.18 5/7/2009 13:00 13.17 0.00 47.82 2.60 23.48 11.01 0.71 0.10 0.17 5/7/2009 13:05 13.53 0.00 48.28 2.30 23.23 10.85 0.63 0.07 0.18 5/7/2009 13:10 12.93 0.29 47.12 3.05 23.39 11.23 0.84 0.12 0.20 5/7/2009 13:15 13.57 0.43 48.08 2.46 24.23 9.56 0.62 0.07 0.18 5/7/2009 13:20 13.65 0.56 46.23 3.38 23.79 10.16 0.89 0.12 0.20 5/7/2009 13:25 12.85 0.98 48.57 2.68 22.77 10.34 0.70 0.09 0.16 5/7/2009 13:35 13.80 0.00 47.32 2.52 24.33 10.16 0.62 0.07 0.16 5/7/2009 13:40 13.70 0.00 46.05 3.06 24.48 10.57 0.83 0.11 0.19 5/7/2009 13:45 13.29 0.00 46.79 2.69 24.85 10.43 0.69 0.10 0.16 5/7/2009 13:50 13.35 0.00 48.74 2.76 20.50 12.71 0.74 0.08 0.16 5/7/2009 13:55 14.01 0.25 46.71 2.96 24.20 9.95 0.79 0.09 0.17 5/7/2009 14:00 12.93 0.43 47.84 2.42 25.09 9.55 0.63 0.09 0.17 5/7/2009 14:05 13.67 1.04 47.74 2.49 24.06 9.22 0.59 0.07 0.16 5/7/2009 14:10 13.34 1.14 48.46 2.54 23.06 9.56 0.62 0.08 0.16 5/7/2009 14:20 13.25 0.00 46.42 2.81 25.67 9.88 0.71 0.11 0.17 5/7/2009 14:25 12.66 0.00 47.78 2.31 25.46 9.92 0.61 0.08 0.17 5/7/2009 14:30 13.06 0.00 47.69 2.31 25.89 9.23 0.59 0.08 0.18 5/7/2009 14:35 13.31 0.40 48.33 2.23 24.74 9.31 0.55 0.06 0.17 5/7/2009 14:40 12.96 0.64 47.96 2.56 24.63 9.44 0.67 0.09 0.17
104 A.4 Run Summary for 13.4% Moisture Content Run
Table A.4.1 Cold gas efficiency determination for 13.4% MC run during efficiency interval. Efficiency Interval (hours) 2.65 Total Product Gas Flow in Efficiency Interval (SL) 113,394 Total Energy in Product Gas in Efficiency Interval (MJ) 684.20 Total Wet Fuel Gasified in Run (kg) 58.8 Average Fuel Moisture Content for Run, wet basis (%) 13.4 Total Dry Fuel Gasified in Run (kg) 52.7 Total Dry Fuel Gasified in Efficiency Interval (kg) 50.8 Total Energy in Fuel in Efficiency Interval (MJ) 1,024.1 Cold Gas Efficiency (%) 66.8
Table A.4.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 13.4% MC run. Total Nitrogen Flow in Product Gas (SL) 54,582 Total Air Entering Gasifier (SL) 69,982 Total Air Entering Gasifier (kg) 83.9 Total Dry Fuel Gasified (kg) 50.8 Air-Fuel Ratio (kg air/kg fuel) 1.65 Air-Fuel Ratio for Complete Combustion 6.29 Equivalence Ratio ( Air-Fuel Ratio / Air-Fuel for 0.263 Complete Combustion)
Table A.4.3 Tar and particulate measurements for 13.4% MC run. Product Gas Filter Mass Difference Tar and Particulate Filter Flow Through after 24 hr. in Matter in Product Gas Filter (SL) Dessicator (mg) (mg/m 3) 1 102.5 69.5 678 2 45.6 41.4 908
105 Table A.4.4 Processed data for each GC interval for 13.4% MC run. Product Gas Ave. Product Gas Gas Flow Total Energy Total Gas Injection Time Temperature HHV In Interval Correction in Product Flow (SL) (°C) (MJ/SL) X 10 3 Factor Gas (MJ) 1/21/2009 11:13 17.66 1.036 1/21/2009 11:18 18.77 5.46 1.054 3,232 17.64 1/21/2009 11:23 19.86 5.65 1.054 3,418 19.32 1/21/2009 11:28 20.92 5.65 1.058 3,493 19.75 1/21/2009 11:33 21.95 5.85 1.061 3,522 20.62 1/21/2009 11:38 22.96 6.01 1.066 3,486 20.97 1/21/2009 11:43 23.95 6.07 1.068 3,523 21.39 1/21/2009 11:48 24.90 6.15 1.075 3,478 21.40 1/21/2009 11:53 25.84 6.11 1.075 3,532 21.59 1/21/2009 11:58 26.75 6.04 1.072 3,532 21.32 1/21/2009 12:03 27.63 6.16 1.076 3,508 21.61 1/21/2009 12:08 28.49 6.21 1.079 3,503 21.76 1/21/2009 12:13 29.33 6.10 1.078 3,478 21.21 1/21/2009 12:18 30.14 6.05 1.085 3,491 21.13 1/21/2009 12:23 30.92 5.97 1.086 3,511 20.98 1/21/2009 12:28 31.68 5.96 1.083 3,542 21.11 1/21/2009 12:33 32.42 6.08 1.080 3,569 21.71 1/21/2009 12:38 33.12 6.16 1.084 3,560 21.92 1/21/2009 12:43 33.81 6.14 1.086 3,582 21.98 1/21/2009 12:48 34.47 6.12 1.092 3,595 22.01 1/21/2009 12:53 35.10 6.18 1.092 3,633 22.45 1/21/2009 12:58 35.71 6.17 1.091 3,639 22.44 1/21/2009 13:07 36.30 6.12 1.091 6,528 39.93 1/21/2009 13:12 36.86 6.00 1.091 3,641 21.83 1/21/2009 13:17 37.39 5.86 1.091 3,705 21.69 1/21/2009 13:22 37.90 5.92 1.094 3,706 21.92 1/21/2009 13:27 38.39 5.97 1.090 3,708 22.13 1/21/2009 13:32 38.84 6.09 1.095 3,684 22.44 1/21/2009 13:37 39.28 6.19 1.099 3,692 22.84 1/21/2009 13:42 39.69 6.13 1.097 3,687 22.59 1/21/2009 13:47 40.07 6.18 1.096 3,640 22.50 1/21/2009 13:52 40.43 6.16 1.100 3,577 22.02
106 Table A.4.5 Unprocessed GC gas composition for 13.4% MC run (mole percent).
Injection Time H2 O2 N2 CH 4 CO CO 2 C2H4 C2H6 C2H2 1/21/2009 11:13 10.42 0.53 55.35 2.05 18.82 12.11 0.64 0.06 0.19 1/21/2009 11:18 12.90 0.31 51.48 2.06 21.62 10.87 0.57 0.07 0.18 1/21/2009 11:23 12.97 0.23 51.40 1.92 21.13 11.65 0.52 0.06 0.15 1/21/2009 11:28 13.38 0.00 49.91 2.08 21.89 11.60 0.53 0.06 0.17 1/21/2009 11:33 13.51 0.00 48.86 2.31 22.28 11.76 0.62 0.07 0.16 1/21/2009 11:38 13.72 0.00 48.68 2.23 23.39 10.91 0.59 0.08 0.16 1/21/2009 11:43 14.15 0.00 47.71 2.28 23.01 11.69 0.58 0.07 0.15 1/21/2009 11:48 14.46 0.00 48.12 2.44 23.05 10.72 0.64 0.08 0.15 1/21/2009 11:53 14.32 0.00 49.00 2.30 22.07 11.08 0.60 0.07 0.16 1/21/2009 11:58 14.10 0.00 48.04 2.40 22.12 12.01 0.67 0.08 0.16 1/21/2009 12:03 13.82 0.00 47.34 2.35 24.27 11.02 0.63 0.09 0.16 1/21/2009 12:08 14.18 0.00 48.14 2.49 22.70 11.19 0.65 0.08 0.16 1/21/2009 12:13 13.66 0.00 48.22 2.09 24.00 10.91 0.55 0.07 0.15 1/21/2009 12:18 14.56 0.19 48.78 2.36 21.95 11.09 0.62 0.07 0.14 1/21/2009 12:23 14.46 0.07 49.14 1.94 22.80 10.61 0.48 0.06 0.15 1/21/2009 12:28 13.73 0.00 48.57 2.31 22.94 10.92 0.60 0.08 0.17 1/21/2009 12:33 13.21 0.33 48.36 2.34 22.99 11.61 0.65 0.09 0.18 1/21/2009 12:38 13.41 0.48 48.49 2.47 22.47 11.44 0.70 0.09 0.17 1/21/2009 12:43 13.30 0.50 49.17 2.21 22.97 10.73 0.60 0.08 0.17 1/21/2009 12:48 13.67 0.98 49.75 2.28 21.97 10.30 0.61 0.07 0.17 1/21/2009 12:53 13.23 1.22 49.99 2.28 21.92 10.30 0.62 0.08 0.16 1/21/2009 12:58 12.91 1.54 50.39 2.23 21.31 10.42 0.59 0.08 0.17 1/21/2009 13:07 13.56 0.31 48.95 2.46 22.39 11.25 0.67 0.08 0.14 1/21/2009 13:12 13.45 0.00 49.06 2.09 23.33 10.85 0.56 0.06 0.17 1/21/2009 13:17 13.38 0.00 49.77 2.15 22.23 11.24 0.58 0.08 0.18 1/21/2009 13:22 13.86 0.00 48.32 2.37 22.45 11.61 0.65 0.09 0.14 1/21/2009 13:27 13.44 0.00 49.27 2.57 20.71 12.30 0.75 0.09 0.17 1/21/2009 13:32 13.55 0.25 47.59 2.50 23.40 11.36 0.69 0.09 0.18 1/21/2009 13:37 13.89 0.28 48.63 2.37 22.64 11.00 0.64 0.09 0.15 1/21/2009 13:42 13.46 0.38 48.09 2.32 23.17 11.26 0.63 0.09 0.17
107 A.5 Run Summary for 12.2% Moisture Content Run
Table A.5.1 Cold gas efficiency determination for 12.2% MC run during efficiency interval. Efficiency Interval (hours) 3.47 Total Product Gas Flow in Efficiency Interval (SL) 148,038 Total Energy in Product Gas in Efficiency Interval (MJ) 902.85 Total Wet Fuel Gasified in Run (kg) 74.8 Average Fuel Moisture Content for Run, wet basis (%) 12.2 Total Dry Fuel Gasified in Run (kg) 65.8 Total Dry Fuel Gasified in Efficiency Interval (kg) 65.8 Total Energy in Fuel in Efficiency Interval (MJ) 1,327.7 Cold Gas Efficiency (%) 68.1
Table A.5.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 12.2% MC run. Total Nitrogen Flow in Product Gas (SL) 70,894 Total Air Entering Gasifier (SL) 90,791 Total Air Entering Gasifier (kg) 108.9 Total Dry Fuel Gasified (kg) 65.8 Air-Fuel Ratio (kg air/kg fuel) 1.66 Air-Fuel Ratio for Complete Combustion 6.29 Equivalence Ratio ( Air-Fuel Ratio / Air-Fuel for 0.263 Complete Combustion)
Table A.5.3 Tar and particulate measurements for 12.2% MC run. Product Gas Filter Mass Tar and Particulate Filter Flow Through Difference after 24 Matter in Product Gas Filter (SL) hr. in Dessicator (mg) (mg/m 3) 1 88.2 30.7 348 2 28.4 12.3 434
108 Table A.5.4 Processed data for each GC interval for 12.2% MC run. Product Gas Ave. Product Gas Gas Flow Total Energy Total Gas Injection Time Temperature HHV In Interval Correction in Product Flow (SL) (°C) (MJ/SL) X 10 3 Factor Gas (MJ) 1/29/2009 11:20 17.66 1.045 1/29/2009 11:24 18.77 5.66 1.043 2,679 15.15 1/29/2009 11:29 19.86 5.64 1.056 3,402 19.19 1/29/2009 11:34 20.92 5.59 1.055 3,446 19.26 1/29/2009 11:39 21.95 5.43 1.062 3,362 18.27 1/29/2009 11:44 22.96 5.75 1.068 3,400 19.55 1/29/2009 11:49 23.95 5.71 1.066 3,514 20.06 1/29/2009 11:54 24.90 5.69 1.070 3,475 19.77 1/29/2009 11:59 25.84 6.04 1.074 3,488 21.05 1/29/2009 12:04 26.75 6.11 1.073 3,508 21.43 1/29/2009 12:09 27.63 6.18 1.077 3,544 21.90 1/29/2009 12:14 28.49 6.19 1.077 3,680 22.77 1/29/2009 12:19 29.33 6.15 1.077 3,678 22.61 1/29/2009 12:24 30.14 6.23 1.081 3,684 22.96 1/29/2009 12:29 30.92 6.16 1.083 3,777 23.25 1/29/2009 12:34 31.68 6.06 1.085 3,774 22.88 1/29/2009 12:39 32.42 6.18 1.086 3,765 23.27 1/29/2009 12:44 33.12 6.22 1.086 3,768 23.44 1/29/2009 12:49 33.81 6.15 1.086 3,717 22.86 1/29/2009 12:54 34.47 6.23 1.090 3,692 23.01 1/29/2009 12:59 35.10 6.25 1.092 3,718 23.22 1/29/2009 13:04 35.71 6.26 1.091 3,676 23.02 1/29/2009 13:09 36.30 6.34 1.093 3,655 23.18 1/29/2009 13:14 36.86 6.23 1.098 3,652 22.75 1/29/2009 13:19 37.39 6.22 1.094 3,657 22.75 1/29/2009 13:24 37.90 6.20 1.097 3,640 22.57 1/29/2009 13:29 38.39 6.20 1.097 3,613 22.42 1/29/2009 13:34 38.84 6.26 1.095 3,589 22.49 1/29/2009 13:39 39.28 6.16 1.095 3,571 22.00 1/29/2009 13:44 39.69 6.18 1.100 3,608 22.29 1/29/2009 13:54 40.07 6.24 1.098 7,176 44.75 1/29/2009 13:59 40.43 6.24 1.097 3,578 22.34 1/29/2009 14:04 40.77 6.15 1.094 3,518 21.65 1/29/2009 14:09 41.08 5.89 1.094 3,480 20.50 1/29/2009 14:14 41.36 5.94 1.100 3,459 20.56 1/29/2009 14:19 41.62 6.25 1.099 3,483 21.79 1/29/2009 14:24 41.86 6.39 1.102 3,491 22.31 1/29/2009 14:29 42.06 6.34 1.097 3,453 21.90 1/29/2009 14:34 42.25 6.22 1.101 3,413 21.21 1/29/2009 14:39 42.41 6.08 1.099 3,411 20.73 1/29/2009 14:43 42.54 6.04 1.104 2,686 16.23 1/29/2009 14:48 42.65 6.18 1.096 3,158 19.51
109 Table A.5.5 Unprocessed GC gas composition for 12.2% MC run (mole percent).
Injection Time H2 O2 N2 CH 4 CO CO 2 C2H4 C2H6 C2H2 1/29/2009 11:20 11.05 0.66 53.46 2.40 22.23 10.53 0.72 0.08 0.19 1/29/2009 11:24 10.99 0.57 54.91 2.03 20.60 11.24 0.65 0.07 0.23 1/29/2009 11:29 13.56 0.35 50.59 2.22 21.33 12.10 0.61 0.07 0.17 1/29/2009 11:34 14.00 0.32 51.96 2.00 18.42 13.44 0.53 0.06 0.11 1/29/2009 11:39 14.53 0.28 50.98 1.98 19.71 12.63 0.51 0.05 0.10 1/29/2009 11:44 14.78 0.00 49.15 2.47 20.99 12.21 0.67 0.08 0.11 1/29/2009 11:49 13.85 0.24 52.34 1.86 20.22 11.60 0.50 0.06 0.12 1/29/2009 11:54 14.29 0.29 49.50 2.23 21.83 11.83 0.59 0.07 0.12 1/29/2009 11:59 14.32 0.29 48.92 2.41 22.67 11.47 0.62 0.08 0.15 1/29/2009 12:04 14.06 0.27 48.93 2.38 22.50 11.77 0.62 0.08 0.17 1/29/2009 12:09 14.18 0.00 48.06 2.67 22.95 11.39 0.73 0.09 0.16 1/29/2009 12:14 14.01 0.00 48.08 2.18 24.11 11.14 0.55 0.07 0.16 1/29/2009 12:19 13.66 0.20 48.48 2.54 23.19 11.59 0.67 0.09 0.17 1/29/2009 12:24 13.94 0.23 48.40 2.56 23.15 11.30 0.68 0.09 0.17 1/29/2009 12:29 14.02 0.00 49.04 2.39 22.60 11.14 0.66 0.08 0.16 1/29/2009 12:34 14.43 0.00 48.39 2.40 22.43 11.63 0.62 0.07 0.17 1/29/2009 12:39 13.81 0.21 48.83 2.71 22.85 11.05 0.73 0.10 0.17 1/29/2009 12:44 14.10 0.00 48.40 2.55 22.53 11.49 0.69 0.08 0.16 1/29/2009 12:49 13.66 0.39 48.93 2.51 22.52 11.42 0.67 0.09 0.16 1/29/2009 12:54 14.11 0.58 48.56 2.70 21.92 11.53 0.72 0.10 0.16 1/29/2009 12:59 14.04 0.47 48.84 2.49 22.39 11.19 0.65 0.08 0.15 1/29/2009 13:04 13.63 0.52 47.94 2.52 23.69 11.05 0.67 0.09 0.16 1/29/2009 13:09 13.40 0.63 48.43 2.47 23.87 10.54 0.63 0.09 0.16 1/29/2009 13:14 14.01 0.32 49.65 2.36 22.99 9.98 0.61 0.07 0.14 1/29/2009 13:19 13.81 0.68 48.50 2.80 21.22 11.94 0.80 0.10 0.16 1/29/2009 13:24 13.70 0.82 49.55 2.30 21.94 10.76 0.59 0.07 0.15 1/29/2009 13:29 13.25 0.92 49.60 2.72 21.89 10.61 0.70 0.09 0.19 1/29/2009 13:34 12.85 1.05 49.88 2.46 22.02 10.65 0.68 0.08 0.17 1/29/2009 13:39 12.72 1.16 50.38 2.41 21.31 10.92 0.69 0.09 0.18 1/29/2009 13:44 13.26 1.27 49.86 2.49 21.47 10.63 0.66 0.07 0.17 1/29/2009 13:54 13.52 0.22 48.04 2.55 23.49 11.15 0.68 0.09 0.14 1/29/2009 13:59 13.56 0.00 47.91 2.82 22.40 11.99 0.80 0.11 0.19 1/29/2009 14:04 12.98 0.00 48.15 2.42 23.19 11.72 0.66 0.09 0.19 1/29/2009 14:09 13.00 0.00 50.20 2.26 21.33 11.74 0.63 0.09 0.17 1/29/2009 14:14 13.49 0.00 48.07 2.50 23.50 11.03 0.65 0.08 0.18 1/29/2009 14:19 13.01 0.00 47.63 2.72 24.09 10.92 0.76 0.10 0.20 1/29/2009 14:24 13.41 0.00 47.55 2.97 23.29 11.19 0.81 0.10 0.21 1/29/2009 14:29 12.91 0.37 48.13 2.66 22.77 11.79 0.74 0.10 0.23 1/29/2009 14:34 12.70 0.57 48.80 2.14 24.70 10.03 0.57 0.08 0.19 1/29/2009 14:39 12.40 0.69 51.35 2.52 21.03 10.59 0.70 0.09 0.21 1/29/2009 14:43 13.16 0.77 49.45 2.34 22.15 10.63 0.63 0.07 0.19 1/29/2009 14:48 12.06 0.83 48.95 2.53 22.82 11.23 0.75 0.10 0.20
110 A.6 Run Summary for 12.8% Moisture Content Run
Table A.6.1 Cold gas efficiency determination for 12.8% MC run during efficiency interval. Efficiency Interval (hours) 3.25 Total Product Gas Flow in Efficiency Interval (SL) 127,656 Total Energy in Product Gas in Efficiency Interval (MJ) 786.31 Total Wet Fuel Gasified in Run (kg) 73.6 Average Fuel Moisture Content for Run, wet basis (%) 12.8 Total Dry Fuel Gasified in Run (kg) 64.1 Total Dry Fuel Gasified in Efficiency Interval (kg) 56.9 Total Energy in Fuel in Efficiency Interval (MJ) 1,147.1 Cold Gas Efficiency (%) 68.5
Table A.6.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 12.8% MC run. Total Nitrogen Flow in Product Gas (SL) 61,308 Total Air Entering Gasifier (SL) 78,516 Total Air Entering Gasifier (kg) 94.2 Total Dry Fuel Gasified (kg) 56.9 Air-Fuel Ratio (kg air/kg fuel) 1.66 Air-Fuel Ratio for Complete Combustion 6.29 Equivalence Ratio ( Air-Fuel Ratio / Air-Fuel for 0.263 Complete Combustion)
Table A.6.3 Tar and particulate measurements for 12.8% MC run. Product Gas Filter Mass Tar and Particulate Filter Flow Through Difference after 24 Matter in Product Filter (SL) hr. in Dessicator (mg) Gas (mg/m 3) 1 75.5 33.4 442 2 51.5 32.0 621
111
Table A.6.4 Processed data for each GC interval for 12.8% MC run. Product Gas Ave. Product Gas Gas Flow Total Energy Total Gas Injection Time Temperature HHV In Interval Correction in Product Flow (SL) (°C) (MJ/SL) X 10 3 Factor Gas (MJ) 2/17/2009 11:50 15.1 1.043 2/17/2009 11:55 16.7 5.98 1.048 3,488 20.86 2/17/2009 12:00 18.6 5.93 1.049 3,534 20.96 2/17/2009 12:05 20.1 5.95 1.056 3,502 20.85 2/17/2009 12:10 21.2 6.05 1.061 3,459 20.92 2/17/2009 12:15 22.1 6.15 1.067 3,443 21.16 2/17/2009 12:20 23.2 6.31 1.070 3,436 21.66 2/17/2009 12:25 24.1 6.17 1.065 3,434 21.18 2/17/2009 12:30 24.6 5.96 1.066 3,395 20.23 2/17/2009 12:35 25.4 6.13 1.065 3,381 20.73 2/17/2009 12:40 26.2 6.30 1.067 3,364 21.19 2/17/2009 12:45 26.6 6.42 1.072 3,333 21.41 2/17/2009 12:50 27.3 6.43 1.070 3,335 21.44 2/17/2009 12:55 27.9 6.27 1.072 3,321 20.82 2/17/2009 13:00 28.4 6.17 1.076 3,370 20.81 2/17/2009 13:05 29.0 6.26 1.074 3,393 21.23 2/17/2009 13:10 29.6 6.28 1.077 3,387 21.27 2/17/2009 13:15 30.0 6.29 1.073 3,399 21.37 2/17/2009 13:20 30.4 6.17 1.075 3,376 20.83 2/17/2009 13:25 30.4 5.99 1.076 3,340 20.02 2/17/2009 13:30 30.9 6.02 1.075 3,311 19.93 2/17/2009 13:35 30.4 5.98 1.076 3,311 19.79 2/17/2009 13:40 30.2 6.09 1.072 3,297 20.08 2/17/2009 13:45 30.8 6.22 1.076 3,278 20.38 2/17/2009 13:50 31.0 6.10 1.079 3,265 19.91 2/17/2009 13:55 32.1 6.09 1.081 3,259 19.84 2/17/2009 14:00 33.6 6.07 1.079 3,265 19.83 2/17/2009 14:05 34.6 6.05 1.082 3,238 19.60 2/17/2009 14:10 34.6 6.17 1.086 3,246 20.04 2/17/2009 14:15 34.6 6.30 1.083 3,229 20.36 2/17/2009 14:20 34.9 6.35 1.083 3,178 20.17 2/17/2009 14:25 36.1 6.03 1.081 3,138 18.93 2/17/2009 14:30 36.3 6.14 1.085 3,121 19.15 2/17/2009 14:35 36.4 6.10 1.079 3,154 19.23 2/17/2009 14:40 36.6 5.92 1.088 3,092 18.31 2/17/2009 14:45 36.3 6.32 1.087 3,057 19.33 2/17/2009 14:50 36.6 6.36 1.084 3,027 19.27 2/17/2009 14:55 36.4 6.27 1.087 2,954 18.52 2/17/2009 15:00 36.1 6.29 1.088 2,842 17.86 2/17/2009 15:05 35.7 6.24 1.089 2,706 16.88
112
Table A.6.5 Unprocessed GC gas composition for 12.8% MC run (mole percent).
Injection Time H2 O2 N2 CH 4 CO CO 2 C2H4 C2H6 C2H2 2/17/2009 11:50 12.31 0.90 51.44 2.43 20.43 11.95 0.71 0.08 0.20 2/17/2009 11:55 12.61 0.96 51.01 2.37 21.06 11.49 0.66 0.07 0.19 2/17/2009 12:00 12.52 0.94 51.20 2.23 20.49 12.05 0.64 0.07 0.19 2/17/2009 12:05 12.74 0.91 50.55 2.35 21.52 11.34 0.66 0.07 0.18 2/17/2009 12:10 13.19 0.88 49.88 2.06 22.55 10.99 0.56 0.07 0.18 2/17/2009 12:15 13.64 0.91 49.93 2.59 21.10 11.04 0.70 0.08 0.17 2/17/2009 12:20 13.63 0.74 49.90 2.73 21.78 10.45 0.76 0.09 0.16 2/17/2009 12:25 13.15 0.72 50.41 2.28 21.20 11.56 0.64 0.07 0.21 2/17/2009 12:30 12.96 0.71 50.26 2.15 22.07 11.24 0.58 0.06 0.19 2/17/2009 12:35 12.79 0.72 48.98 2.74 22.07 11.85 0.79 0.10 0.17 2/17/2009 12:40 12.86 0.69 49.74 2.85 20.87 11.99 0.87 0.11 0.20 2/17/2009 12:45 13.21 0.67 48.48 3.05 22.35 11.40 0.85 0.11 0.19 2/17/2009 12:50 12.86 0.54 48.29 2.47 23.59 11.43 0.68 0.09 0.20 2/17/2009 12:55 13.14 0.39 48.42 2.56 22.94 11.67 0.71 0.08 0.21 2/17/2009 13:00 13.52 0.27 49.36 2.35 22.82 10.96 0.64 0.07 0.19 2/17/2009 13:05 13.19 0.26 48.12 2.98 22.41 12.05 0.86 0.12 0.20 2/17/2009 13:10 13.37 0.36 49.63 2.64 21.58 11.42 0.74 0.09 0.20 2/17/2009 13:15 12.71 0.53 47.89 2.83 22.81 12.07 0.83 0.12 0.20 2/17/2009 13:20 12.85 0.58 50.53 2.26 21.40 11.45 0.65 0.08 0.21 2/17/2009 13:25 12.78 0.65 49.30 2.29 22.59 11.43 0.64 0.08 0.19 2/17/2009 13:30 12.40 0.63 50.03 2.16 22.68 11.13 0.61 0.08 0.19 2/17/2009 13:35 12.73 0.77 50.18 2.37 21.36 11.48 0.65 0.07 0.20 2/17/2009 13:40 12.36 0.86 49.98 2.84 20.28 12.26 0.85 0.11 0.19 2/17/2009 13:45 12.51 0.95 49.96 2.71 21.07 11.51 0.81 0.10 0.21 2/17/2009 13:50 13.03 0.62 49.92 2.12 22.22 10.97 0.58 0.07 0.19 2/17/2009 13:55 12.77 0.46 50.23 2.82 21.64 10.80 0.81 0.12 0.16 2/17/2009 14:00 12.96 0.00 50.02 2.59 20.97 12.01 0.77 0.09 0.19 2/17/2009 14:05 12.65 0.00 48.24 2.54 23.87 11.35 0.71 0.10 0.20 2/17/2009 14:10 13.09 0.00 48.61 2.53 23.12 11.06 0.70 0.09 0.21 2/17/2009 14:15 12.97 0.00 47.58 3.15 22.30 12.16 0.92 0.13 0.22 2/17/2009 14:20 12.52 0.00 48.61 2.77 22.93 11.34 0.80 0.11 0.22 2/17/2009 14:25 12.15 0.00 51.02 2.62 20.66 11.68 0.75 0.10 0.24 2/17/2009 14:30 12.60 0.00 47.34 2.96 23.46 11.73 0.87 0.13 0.23 2/17/2009 14:35 12.25 0.00 50.53 2.53 20.00 12.80 0.80 0.10 0.22 2/17/2009 14:40 12.85 0.20 48.79 2.41 23.19 11.06 0.65 0.08 0.21 2/17/2009 14:45 13.12 0.31 47.10 3.26 21.70 12.61 0.95 0.13 0.21 2/17/2009 14:50 12.51 0.36 48.51 2.70 22.15 12.07 0.77 0.10 0.21 2/17/2009 14:55 12.86 0.43 48.02 2.90 22.07 11.99 0.83 0.11 0.20 2/17/2009 15:00 12.59 0.51 49.15 2.62 22.42 11.00 0.72 0.10 0.21 2/17/2009 15:05 12.85 0.59 49.09 2.66 22.23 10.88 0.72 0.10 0.20
113 A.7 Run Summary for 12.5% Moisture Content Run
Table A.7.1 Cold gas efficiency determination for 12.5% MC run during efficiency interval. Efficiency Interval (hours) 3.00 Total Product Gas Flow in Efficiency Interval (SL) 119,115 Total Energy in Product Gas in Efficiency Interval (MJ) 734.87 Total Wet Fuel Gasified in Run (kg) 68.8 Average Fuel Moisture Content for Run, wet basis (%) 12.5 Total Dry Fuel Gasified in Run (kg) 60.2 Total Dry Fuel Gasified in Efficiency Interval (kg) 54.8 Total Energy in Fuel in Efficiency Interval (MJ) 1,105.4 Cold Gas Efficiency (%) 66.5
Table A.7.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 12.5% MC run. Total Nitrogen Flow in Product Gas (SL) 56,888 Total Air Entering Gasifier (SL) 72,854 Total Air Entering Gasifier (kg) 87.4 Total Dry Fuel Gasified (kg) 54.8 Air-Fuel Ratio (kg air/kg fuel) 1.59 Air-Fuel Ratio for Complete Combustion 6.29 Equivalence Ratio ( Air-Fuel Ratio / Air-Fuel for 0.253 Complete Combustion)
Table A.7.3 Tar and particulate measurements for 12.5% MC run. Product Gas Filter Mass Tar and Particulate Filter Flow Through Difference after 24 Matter in Product Gas Filter (SL) hr. in Dessicator (mg) (mg/m 3) 1 31.6 28.4 900 2 50.3 27.3 543 3 25.5 17.8 699
114 Table A.7.4 Processed data for each GC interval for 12.5% MC run. Product Gas Ave. Product Gas Gas Flow Total Energy Total Gas Injection Time Temperature HHV In Interval Correction in Product Flow (SL) (°C) (MJ/SL) X 10 3 Factor Gas (MJ) 5/12/2009 12:35 20.79 1.062 5/12/2009 12:40 22.71 6.23 1.063 3,300 20.54 5/12/2009 12:45 24.43 6.20 1.069 3,275 20.31 5/12/2009 12:50 26.19 6.25 1.071 3,396 21.24 5/12/2009 12:55 27.60 6.34 1.075 3,506 22.22 5/12/2009 13:00 28.76 6.37 1.078 3,482 22.19 5/12/2009 13:05 29.58 6.35 1.075 3,462 21.97 5/12/2009 13:10 30.76 6.29 1.077 3,458 21.76 5/12/2009 13:15 31.64 6.17 1.081 3,428 21.16 5/12/2009 13:20 32.59 6.28 1.084 3,400 21.36 5/12/2009 13:25 33.36 6.21 1.079 3,419 21.23 5/12/2009 13:30 34.27 6.09 1.085 3,396 20.70 5/12/2009 13:35 35.08 6.22 1.088 3,380 21.04 5/12/2009 13:40 35.57 6.22 1.089 3,351 20.84 5/12/2009 13:45 35.69 6.10 1.086 3,273 19.95 5/12/2009 13:50 35.67 6.03 1.097 3,311 19.97 5/12/2009 13:55 36.60 6.17 1.088 3,383 20.88 5/12/2009 14:00 37.91 6.13 1.090 3,345 20.50 5/12/2009 14:05 38.76 6.05 1.096 3,333 20.16 5/12/2009 14:10 39.48 6.10 1.096 3,370 20.56 5/12/2009 14:15 40.12 6.12 1.101 3,330 20.37 5/12/2009 14:20 40.78 5.92 1.096 3,365 19.91 5/12/2009 14:25 41.52 5.95 1.097 3,335 19.83 5/12/2009 14:30 41.74 6.14 1.100 3,298 20.25 5/12/2009 14:35 41.90 6.07 1.099 3,293 19.98 5/12/2009 14:40 42.59 6.09 1.100 3,273 19.92 5/12/2009 14:45 43.11 6.14 1.101 3,226 19.81 5/12/2009 14:50 43.69 6.12 1.103 3,163 19.36 5/12/2009 14:55 44.13 6.19 1.106 3,238 20.04 5/12/2009 15:00 45.01 6.20 1.104 3,206 19.88 5/12/2009 15:05 45.36 6.20 1.108 3,041 18.85 5/12/2009 15:10 45.87 6.25 1.104 3,136 19.59 5/12/2009 15:15 46.11 6.22 1.105 3,100 19.27 5/12/2009 15:20 45.72 6.11 1.105 3,223 19.70 5/12/2009 15:25 46.19 6.16 1.107 3,214 19.81 5/12/2009 15:30 46.52 6.24 1.106 3,201 19.98 5/12/2009 15:35 46.40 6.15 1.108 3,207 19.73
115 Table A.7.5 Unprocessed GC gas composition for 12.5% MC run (mole percent).
Injection Time H2 O2 N2 CH 4 CO CO 2 C2H4 C2H6 C2H2 5/12/2009 12:35 12.80 0.23 49.08 2.41 23.94 10.22 0.61 0.08 0.22 5/12/2009 12:40 13.19 0.21 48.95 2.68 22.42 11.24 0.71 0.08 0.21 5/12/2009 12:45 13.35 0.00 48.85 2.42 23.56 10.47 0.65 0.08 0.18 5/12/2009 12:50 13.46 0.00 48.11 2.87 22.36 11.32 0.79 0.10 0.19 5/12/2009 12:55 13.36 0.00 48.06 2.72 23.23 10.89 0.77 0.09 0.20 5/12/2009 13:00 13.57 0.00 47.31 2.70 23.65 10.90 0.74 0.09 0.20 5/12/2009 13:05 12.96 0.00 48.36 2.91 22.14 11.58 0.82 0.11 0.21 5/12/2009 13:10 12.98 0.22 48.12 2.68 23.08 11.41 0.76 0.09 0.19 5/12/2009 13:15 13.47 0.26 49.51 2.59 21.07 11.69 0.73 0.09 0.18 5/12/2009 13:20 13.26 0.39 48.13 3.10 22.12 11.39 0.89 0.11 0.19 5/12/2009 13:25 12.93 0.00 49.99 2.69 20.32 12.14 0.79 0.09 0.17 5/12/2009 13:30 13.18 0.00 47.77 2.78 22.91 11.47 0.79 0.10 0.15 5/12/2009 13:35 13.50 0.00 48.04 2.58 22.63 11.39 0.71 0.08 0.17 5/12/2009 13:40 13.68 0.00 47.58 2.81 22.06 11.95 0.82 0.10 0.17 5/12/2009 13:45 12.77 0.00 49.11 2.19 23.46 10.88 0.59 0.08 0.15 5/12/2009 13:50 14.18 0.00 48.41 2.36 23.49 10.16 0.61 0.07 0.12 5/12/2009 13:55 13.37 0.00 47.77 2.73 22.23 12.06 0.79 0.10 0.17 5/12/2009 14:00 13.74 0.00 48.26 2.75 20.56 12.78 0.83 0.10 0.15 5/12/2009 14:05 13.93 0.00 48.65 2.51 21.74 11.56 0.71 0.08 0.15 5/12/2009 14:10 13.71 0.00 48.26 2.81 21.51 12.05 0.80 0.09 0.18 5/12/2009 14:15 13.98 0.00 48.50 2.36 23.01 10.87 0.63 0.07 0.14 5/12/2009 14:20 13.47 0.00 49.68 2.35 20.99 11.80 0.63 0.07 0.15 5/12/2009 14:25 13.41 0.00 48.12 2.71 21.72 12.32 0.79 0.11 0.17 5/12/2009 14:30 13.36 0.00 48.11 2.56 23.26 11.29 0.69 0.09 0.18 5/12/2009 14:35 13.23 0.00 49.25 2.56 21.80 11.64 0.72 0.08 0.17 5/12/2009 14:40 13.35 0.00 48.08 2.79 22.17 11.82 0.80 0.10 0.17 5/12/2009 14:45 13.44 0.00 48.56 2.65 21.93 11.79 0.75 0.08 0.18 5/12/2009 14:50 13.38 0.00 47.84 2.52 23.18 11.34 0.71 0.08 0.18 5/12/2009 14:55 13.40 0.19 48.75 2.71 22.27 10.98 0.76 0.09 0.19 5/12/2009 15:00 13.07 0.22 48.29 2.70 22.41 11.55 0.74 0.10 0.18 5/12/2009 15:05 13.43 0.00 48.05 2.68 22.88 11.07 0.74 0.09 0.17 5/12/2009 15:10 12.81 0.00 48.12 3.03 21.92 11.94 0.88 0.12 0.21 5/12/2009 15:15 12.71 0.00 47.85 2.48 23.90 11.17 0.69 0.09 0.19 5/12/2009 15:20 13.22 0.00 48.20 2.62 22.14 11.90 0.74 0.09 0.19 5/12/2009 15:25 13.17 0.24 48.37 2.97 21.54 11.89 0.83 0.10 0.18
116 A.8 Run Summary for 22.6% Moisture Content Run
Table A.8.1 Cold gas efficiency determination for 22.6% MC run during efficiency interval. Efficiency Interval (hours) 2.67 Total Product Gas Flow in Efficiency Interval (SL) 98,602 Total Energy in Product Gas in Efficiency Interval (MJ) 511.36 Total Wet Fuel Gasified in Run (kg) 61.2 Average Fuel Moisture Content for Run, wet basis (%) 22.6 Total Dry Fuel Gasified in Run (kg) 47.4 Total Dry Fuel Gasified in Efficiency Interval (kg) 39.2 Total Energy in Fuel in Efficiency Interval (MJ) 790.7 Cold Gas Efficiency (%) 64.7
Table A.8.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 22.6% MC run. Total Nitrogen Flow in Product Gas (SL) 51,483 Total Air Entering Gasifier (SL) 65,933 Total Air Entering Gasifier (kg) 79.1 Total Dry Fuel Gasified (kg) 39.2 Air-Fuel Ratio (kg air/kg fuel) 2.02 Air-Fuel Ratio for Complete Combustion 6.29 Equivalence Ratio ( Air-Fuel Ratio / Air-Fuel for 0.321 Complete Combustion)
Table A.8.3 Tar and particulate measurements for 22.6% MC run. Product Gas Filter Mass Tar and Particulate Filter Flow Through Difference after 24 Matter in Product Gas Filter (SL) hr. in Dessicator (mg) (mg/m 3) 1 102.7 31.8 310
117
Table A.8.4 Processed data for each GC interval for 22.6% MC run. Product Gas Ave. Product Gas Gas Flow Total Energy Total Gas Injection Time Temperature HHV In Interval Correction in Product Flow (SL) (°C) (MJ/SL) X 10 3 Factor Gas (MJ) 3/26/2009 14:15 16.60 1.039 3/26/2009 14:20 16.31 5.16 1.039 2,008 10.37 3/26/2009 14:25 17.17 5.46 1.037 3,421 18.67 3/26/2009 14:30 18.65 5.30 1.035 3,366 17.84 3/26/2009 14:35 20.71 4.96 1.043 3,365 16.69 3/26/2009 14:40 22.42 5.16 1.050 3,416 17.63 3/26/2009 14:45 23.76 5.38 1.059 3,408 18.35 3/26/2009 14:50 25.04 5.42 1.062 3,330 18.07 3/26/2009 14:55 25.83 5.34 1.065 3,298 17.62 3/26/2009 15:00 27.12 5.43 1.066 3,267 17.73 3/26/2009 15:05 28.14 5.58 1.070 3,177 17.72 3/26/2009 15:10 28.80 5.56 1.071 3,189 17.72 3/26/2009 15:15 29.28 5.08 1.060 3,194 16.24 3/26/2009 15:20 29.60 5.02 1.076 3,103 15.57 3/26/2009 15:25 29.89 5.47 1.075 3,113 17.04 3/26/2009 15:30 30.19 5.49 1.074 3,145 17.27 3/26/2009 15:35 30.87 5.25 1.069 3,170 16.62 3/26/2009 15:40 31.11 5.35 1.077 3,122 16.71 3/26/2009 15:45 31.81 5.37 1.069 3,186 17.10 3/26/2009 15:50 32.01 5.09 1.070 3,120 15.88 3/26/2009 15:55 32.53 4.95 1.069 3,074 15.23 3/26/2009 16:00 33.72 4.96 1.074 3,033 15.06 3/26/2009 16:05 34.04 5.25 1.076 2,999 15.74 3/26/2009 16:10 34.21 5.25 1.072 3,041 15.95 3/26/2009 16:15 34.34 5.23 1.076 2,964 15.51 3/26/2009 16:20 34.86 5.08 1.071 2,950 14.97 3/26/2009 16:25 35.19 4.74 1.071 2,916 13.83 3/26/2009 16:30 35.66 4.85 1.073 2,804 13.61 3/26/2009 16:35 35.45 4.97 1.074 2,753 13.67 3/26/2009 16:40 35.42 4.88 1.071 2,705 13.19 3/26/2009 16:45 34.93 4.94 1.075 2,681 13.25 3/26/2009 16:50 34.90 4.92 1.069 2,960 14.57 3/26/2009 16:55 36.15 4.78 1.073 2,784 13.31 3/26/2009 17:00 37.29 4.89 1.073 540 10.37
118 Table A.8.5 Unprocessed GC gas composition for 22.6% MC run (mole percent).
Injection Time H2 O2 N2 CH 4 CO CO 2 C2H4 C2H6 C2H2 3/26/2009 14:20 7.78 2.85 60.28 1.47 20.04 6.83 0.38 0.06 0.10 3/26/2009 14:20 7.78 2.85 60.28 1.47 20.04 6.83 0.38 0.06 0.10 3/26/2009 14:25 10.98 0.45 51.60 2.41 20.52 12.45 0.74 0.10 0.26 3/26/2009 14:30 10.91 0.41 54.71 1.78 17.59 13.44 0.50 0.06 0.15 3/26/2009 14:35 11.50 0.37 53.70 1.99 18.39 13.06 0.52 0.06 0.11 3/26/2009 14:40 12.36 0.36 52.60 2.09 18.18 13.22 0.58 0.06 0.12 3/26/2009 14:45 13.21 0.39 51.20 2.18 19.25 12.71 0.58 0.06 0.11 3/26/2009 14:50 13.42 0.38 51.51 1.98 18.70 12.95 0.50 0.05 0.09 3/26/2009 14:55 13.19 0.35 52.23 2.07 18.77 12.21 0.51 0.06 0.11 3/26/2009 15:00 13.39 0.36 51.48 2.31 18.18 12.93 0.62 0.07 0.13 3/26/2009 15:05 13.81 0.34 50.28 2.43 18.61 13.23 0.62 0.09 0.13 3/26/2009 15:10 13.82 0.35 51.00 2.22 18.10 13.27 0.56 0.07 0.13 3/26/2009 15:15 12.07 0.32 54.72 1.78 16.02 13.83 0.46 0.06 0.12 3/26/2009 15:20 14.27 0.31 51.29 2.00 18.07 12.90 0.48 0.05 0.10 3/26/2009 15:25 13.95 0.29 49.84 2.26 19.34 12.92 0.57 0.08 0.10 3/26/2009 15:30 13.95 0.00 50.59 2.15 18.02 13.45 0.56 0.06 0.12 3/26/2009 15:35 12.77 0.24 52.90 2.04 17.66 13.07 0.54 0.06 0.11 3/26/2009 15:40 14.03 0.21 50.19 2.39 18.63 13.15 0.59 0.08 0.07 3/26/2009 15:45 12.67 0.00 51.97 2.04 18.13 13.36 0.56 0.08 0.11 3/26/2009 15:50 12.24 0.00 53.20 1.94 18.34 12.69 0.49 0.06 0.08 3/26/2009 15:55 12.18 0.00 53.90 1.98 17.35 13.21 0.50 0.06 0.08 3/26/2009 16:00 13.09 0.00 52.67 2.02 17.14 13.47 0.54 0.06 0.10 3/26/2009 16:05 13.03 0.00 50.65 2.41 18.44 13.66 0.67 0.10 0.10 3/26/2009 16:10 12.14 0.00 52.78 2.02 18.13 13.18 0.51 0.07 0.09 3/26/2009 16:15 12.91 0.00 50.37 2.20 19.55 13.27 0.58 0.08 0.10 3/26/2009 16:20 12.35 0.00 54.53 1.96 15.70 13.94 0.50 0.06 0.11 3/26/2009 16:25 11.90 0.00 54.01 1.87 17.07 13.61 0.47 0.06 0.09 3/26/2009 16:30 11.83 0.00 53.32 1.85 18.43 12.99 0.49 0.07 0.08 3/26/2009 16:35 12.15 0.20 53.57 2.07 17.17 13.39 0.56 0.07 0.08 3/26/2009 16:40 11.56 0.28 54.62 1.93 16.78 13.48 0.46 0.07 0.07 3/26/2009 16:45 12.53 0.34 52.81 2.19 16.87 13.64 0.58 0.08 0.10 3/26/2009 16:50 11.15 0.39 55.33 1.86 16.80 13.06 0.46 0.06 0.09 3/26/2009 16:55 11.55 0.64 54.75 1.84 16.88 12.82 0.47 0.05 0.10 3/26/2009 17:00 11.07 0.29 53.87 1.82 18.72 12.72 0.49 0.06 0.09
119 A.9 Run Summary for 21.6% Moisture Content Run
Table A.9.1 Cold gas efficiency determination for 21.6% MC run during efficiency interval. Efficiency Interval (hours) 3.6 Total Product Gas Flow in Efficiency Interval (SL) 113,867 Total Energy in Product Gas in Efficiency Interval (MJ) 581.09 Total Wet Fuel Gasified in Run (kg) 57.6 Average Fuel Moisture Content for Run, wet basis (%) 21.6 Total Dry Fuel Gasified in Run (kg) 45.2 Total Dry Fuel Gasified in Efficiency Interval (kg) 45.2 Total Energy in Fuel in Efficiency Interval (MJ) 910.6 Cold Gas Efficiency (%) 63.8
Table A.9.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 21.6% MC run. Total Nitrogen Flow in Product Gas (SL) 59,870 Total Air Entering Gasifier (SL) 76,674 Total Air Entering Gasifier (kg) 92.0 Total Dry Fuel Gasified (kg) 45.2 Air-Fuel Ratio (kg air/kg fuel) 2.04 Air-Fuel Ratio for Complete Combustion 6.29 Equivalence Ratio ( Air-Fuel Ratio / Air-Fuel for 0.324 Complete Combustion)
Table A.9.3 Tar and particulate measurements for 21.6% MC run. Product Gas Filter Mass Tar and Particulate Filter Flow Through Difference after 24 Matter in Product Gas Filter (SL) hr. in Dessicator (mg) (mg/m 3) 1 54.1 28.0 518 2 62.0 29.8 481 3 37.4 34.3 917
120 Table A.9.4 Processed data for each GC interval for 21.6% MC run. Product Gas Ave. Product Gas Gas Flow Total Energy Total Gas Injection Time Temperature HHV In Interval Correction in Product Flow (SL) (°C) (MJ/SL) X 10 3 Factor Gas (MJ) 4/7/2009 12:00 13.60 1.030 4/7/2009 12:05 14.97 5.04 1.024 1,060 5.34 4/7/2009 12:10 16.64 5.03 1.035 2,550 12.84 4/7/2009 12:15 18.53 5.43 1.039 2,506 13.62 4/7/2009 12:20 19.99 4.98 1.034 2,465 12.27 4/7/2009 12:25 21.29 4.58 1.038 2,367 10.83 4/7/2009 12:30 22.38 4.71 1.040 2,291 10.79 4/7/2009 12:35 23.54 5.01 1.052 2,183 10.93 4/7/2009 12:40 24.43 5.25 1.048 2,188 11.48 4/7/2009 12:45 25.77 5.38 1.049 2,234 12.02 4/7/2009 12:50 25.70 5.13 1.049 2,274 11.66 4/7/2009 13:00 28.05 4.92 1.051 4,428 21.76 4/7/2009 13:05 29.00 5.00 1.057 2,185 10.94 4/7/2009 13:10 28.99 5.32 1.063 2,120 11.27 4/7/2009 13:15 30.23 5.14 1.055 2,824 14.51 4/7/2009 13:20 31.58 4.70 1.060 3,008 14.14 4/7/2009 13:25 33.03 4.84 1.065 2,992 14.49 4/7/2009 13:30 34.32 4.94 1.062 2,940 14.54 4/7/2009 13:35 35.29 4.83 1.067 2,921 14.10 4/7/2009 13:40 35.82 4.69 1.066 2,975 13.95 4/7/2009 13:45 36.28 4.72 1.071 2,998 14.13 4/7/2009 13:50 36.38 4.87 1.071 2,912 14.19 4/7/2009 13:55 36.19 5.18 1.075 2,906 15.05 4/7/2009 14:00 36.21 5.36 1.075 2,883 15.44 4/7/2009 14:05 36.19 5.03 1.068 2,878 14.48 4/7/2009 14:10 37.84 4.99 1.076 2,888 14.41 4/7/2009 14:15 37.68 5.02 1.075 2,913 14.62 4/7/2009 14:20 36.62 4.73 1.069 2,861 13.53 4/7/2009 14:25 36.68 5.10 1.084 2,752 14.05 4/7/2009 14:30 37.20 5.45 1.077 2,692 14.66 4/7/2009 14:35 37.68 5.14 1.076 2,828 14.54 4/7/2009 14:40 38.61 4.88 1.074 2,795 13.63 4/7/2009 14:45 39.06 5.22 1.083 2,806 14.66 4/7/2009 14:50 39.03 5.41 1.080 2,869 15.51 4/7/2009 14:55 39.10 5.30 1.085 2,792 14.81 4/7/2009 15:00 38.57 5.43 1.084 2,726 14.79 4/7/2009 15:05 38.15 5.41 1.083 2,825 15.30 4/7/2009 15:09 38.03 5.49 1.083 2,816 15.45 4/7/2009 15:15 37.46 5.16 1.073 2,707 13.97 4/7/2009 15:20 37.33 4.95 1.076 2,769 13.69 4/7/2009 15:24 37.11 5.49 1.082 2,710 14.88 4/7/2009 15:29 36.82 5.64 1.084 2,391 13.49 4/7/2009 15:34 37.83 5.57 1.078 2,281 12.70 4/7/2009 15:39 37.42 5.60 1.084 1,359 7.61
121
Table A.9.5 Unprocessed GC gas composition for 21.6% MC run (mole percent).
Injection Time H2 O2 N2 CH 4 CO CO 2 C2H4 C2H6 C2H2 4/7/2009 12:00 11.23 0.20 51.63 2.36 19.96 13.29 0.67 0.08 0.25 4/7/2009 12:05 10.44 0.20 56.50 1.70 16.36 13.79 0.44 0.05 0.16 4/7/2009 12:10 11.68 0.28 51.37 2.48 19.27 13.70 0.68 0.11 0.13 4/7/2009 12:15 11.75 0.30 52.34 2.18 18.67 13.42 0.61 0.09 0.15 4/7/2009 12:20 10.77 0.36 55.50 1.92 15.95 14.45 0.50 0.08 0.10 4/7/2009 12:25 11.03 0.40 56.55 1.79 15.05 14.17 0.50 0.06 0.12 4/7/2009 12:30 10.51 0.46 54.73 2.10 17.51 13.62 0.55 0.08 0.07 4/7/2009 12:35 12.15 0.52 53.37 1.88 17.87 12.97 0.51 0.07 0.12 4/7/2009 12:40 11.06 0.44 52.61 2.46 18.33 13.56 0.67 0.11 0.18 4/7/2009 12:45 11.03 0.40 52.11 2.37 18.78 13.81 0.64 0.12 0.14 4/7/2009 12:50 11.06 0.61 55.17 2.10 15.72 13.96 0.62 0.08 0.16 4/7/2009 13:00 10.93 0.00 54.05 2.06 17.68 13.64 0.58 0.09 0.16 4/7/2009 13:05 11.09 0.00 53.13 2.01 19.10 13.06 0.52 0.09 0.11 4/7/2009 13:10 11.65 0.00 51.55 2.51 20.08 12.64 0.68 0.11 0.15 4/7/2009 13:15 10.59 0.00 55.72 1.91 17.06 13.21 0.54 0.08 0.16 4/7/2009 13:20 10.89 0.00 55.42 1.84 17.37 13.05 0.47 0.06 0.13 4/7/2009 13:25 11.42 0.00 53.74 2.14 18.03 13.34 0.56 0.07 0.09 4/7/2009 13:30 10.81 0.00 54.65 2.27 17.00 13.99 0.64 0.09 0.11 4/7/2009 13:35 11.27 0.00 54.67 2.07 16.70 13.82 0.52 0.07 0.08 4/7/2009 13:40 10.66 0.00 55.55 1.75 17.74 13.14 0.46 0.05 0.10 4/7/2009 13:45 10.99 0.00 54.89 1.85 18.42 12.74 0.49 0.06 0.10 4/7/2009 13:50 11.29 0.00 53.73 2.04 18.02 13.38 0.56 0.07 0.10 4/7/2009 13:55 11.71 0.22 52.00 2.40 19.06 13.08 0.67 0.10 0.13 4/7/2009 14:00 11.81 0.34 52.70 2.35 17.89 13.40 0.65 0.09 0.16 4/7/2009 14:05 10.68 0.43 55.61 2.00 16.70 13.35 0.53 0.08 0.13 4/7/2009 14:10 12.10 0.34 52.97 2.34 16.96 13.83 0.66 0.08 0.17 4/7/2009 14:15 11.23 0.43 54.79 1.77 18.00 12.68 0.45 0.05 0.11 4/7/2009 14:20 10.50 0.54 55.74 1.69 17.41 13.01 0.42 0.05 0.09 4/7/2009 14:25 12.48 0.69 52.03 2.37 18.64 12.18 0.64 0.09 0.15 4/7/2009 14:30 11.75 0.70 52.85 2.15 18.12 12.88 0.62 0.08 0.17 4/7/2009 14:35 11.03 0.33 55.86 2.23 16.70 12.36 0.65 0.08 0.13 4/7/2009 14:40 11.61 0.00 54.25 2.06 16.16 14.16 0.58 0.07 0.13 4/7/2009 14:45 12.36 0.00 49.76 2.46 20.36 13.15 0.67 0.11 0.15 4/7/2009 14:50 12.00 0.00 52.96 2.21 17.67 13.29 0.64 0.08 0.18 4/7/2009 14:55 12.82 0.00 51.00 2.47 18.32 13.56 0.67 0.09 0.16 4/7/2009 15:00 12.55 0.00 50.83 2.12 19.76 13.04 0.56 0.08 0.18 4/7/2009 15:05 12.53 0.00 51.39 2.37 18.74 13.18 0.66 0.09 0.17 4/7/2009 15:09 12.51 0.00 50.84 2.47 19.23 12.92 0.67 0.09 0.18 4/7/2009 15:15 11.44 0.21 55.05 2.03 16.02 13.87 0.56 0.07 0.16 4/7/2009 15:20 11.95 0.25 52.62 2.05 18.15 13.55 0.55 0.07 0.14 4/7/2009 15:24 12.51 0.30 49.54 2.76 20.08 13.06 0.70 0.12 0.15 4/7/2009 15:29 12.35 0.37 52.70 2.23 18.95 11.87 0.58 0.09 0.16
122 A.10 Run Summary for 21.5% Moisture Content Run
Table A.10.1 Cold gas efficiency determination for 21.5% MC run during efficiency interval. Efficiency Interval (hours) 2.80 Total Product Gas Flow in Efficiency Interval (SL) 116,881 Total Energy in Product Gas in Efficiency Interval (MJ) 581.79 Total Wet Fuel Gasified in Run (kg) 68.2 Average Fuel Moisture Content for Run, wet basis (%) 21.5 Total Dry Fuel Gasified in Run (kg) 53.5 Total Dry Fuel Gasified in Efficiency Interval (kg) 44.0 Total Energy in Fuel in Efficiency Interval (MJ) 886.0 Cold Gas Efficiency (%) 65.7
Table A.10.2 Determination of efficiency interval equivalence ratio from product gas nitrogen content for 21.5% MC run. Total Nitrogen Flow in Product Gas (SL) 61,286 Total Air Entering Gasifier (SL) 78,487 Total Air Entering Gasifier (kg) 94.2 Total Dry Fuel Gasified (kg) 44.0 Air-Fuel Ratio (kg air/kg fuel) 2.14 Air-Fuel Ratio for Complete Combustion 6.29 Equivalence Ratio ( Air-Fuel Ratio / Air-Fuel for 0.341 Complete Combustion)
Table A.10.3 Tar and particulate measurements for 21.5% MC run. Product Gas Filter Mass Tar and Particulate Filter Flow Through Difference after 24 Matter in Product Gas Filter (SL) hr. in Dessicator (mg) (mg/m 3) 1 44.4 10.2 230 2 34.3 5.2 152 3 31.2 5.9 189
123 Table A.10.4 Processed data for each GC interval for 21.5% MC run. Product Gas Ave. Product Gas Gas Flow Total Energy Total Gas Injection Time Temperature HHV In Interval Correction in Product Flow (SL) (°C) (MJ/SL) X 10 3 Factor Gas (MJ) 4/14/2009 11:35 10.80 1.022 4/14/2009 11:40 12.25 4.79 1.027 3,185 15.26 4/14/2009 11:45 14.25 5.04 1.038 3,349 16.87 4/14/2009 11:50 16.65 5.16 1.041 3,511 18.13 4/14/2009 11:55 18.99 5.00 1.047 3,487 17.43 4/14/2009 12:00 20.53 5.14 1.052 3,502 18.01 4/14/2009 12:05 22.21 5.12 1.047 3,458 17.69 4/14/2009 12:10 23.92 4.91 1.053 3,400 16.70 4/14/2009 12:15 24.95 4.84 1.055 3,383 16.39 4/14/2009 12:20 26.11 4.75 1.057 3,358 15.96 4/14/2009 12:25 26.30 4.64 1.052 3,356 15.58 4/14/2009 12:30 26.71 5.12 1.065 3,426 17.55 4/14/2009 12:35 27.13 5.38 1.061 3,529 18.99 4/14/2009 12:40 29.58 5.01 1.064 3,469 17.39 4/14/2009 12:45 30.30 5.13 1.072 3,475 17.83 4/14/2009 12:50 30.87 5.02 1.066 3,500 17.56 4/14/2009 12:55 31.64 4.71 1.067 3,444 16.21 4/14/2009 13:00 32.66 4.85 1.077 3,448 16.72 4/14/2009 13:05 33.36 4.99 1.074 3,510 17.52 4/14/2009 13:10 33.54 5.30 1.079 3,467 18.37 4/14/2009 13:15 34.13 5.24 1.072 3,467 18.16 4/14/2009 13:20 34.10 4.90 1.076 3,588 17.58 4/14/2009 13:25 34.97 4.64 1.069 3,623 16.82 4/14/2009 13:30 36.03 4.65 1.080 3,642 16.94 4/14/2009 13:35 37.37 4.89 1.080 3,500 17.12 4/14/2009 13:40 37.55 4.95 1.086 3,453 17.10 4/14/2009 13:45 38.39 4.89 1.080 3,546 17.34 4/14/2009 13:50 39.71 4.82 1.086 3,465 16.70 4/14/2009 13:55 40.35 5.13 1.092 3,422 17.55 4/14/2009 14:00 40.98 5.21 1.091 3,549 18.48 4/14/2009 14:05 41.04 5.15 1.094 3,597 18.52 4/14/2009 14:10 41.02 5.17 1.091 3,656 18.90 4/14/2009 14:15 40.48 5.00 1.088 3,523 17.63 4/14/2009 14:20 42.53 4.81 1.087 3,490 16.80 4/14/2009 14:25 43.08 4.75 1.094 2,104 10.00
124 Table A.10.5 Unprocessed GC gas composition for 21.5% MC run (mole percent).
Injection Time H2 O2 N2 CH 4 CO CO 2 C2H4 C2H6 C2H2 4/14/2009 11:35 10.92 0.32 56.35 2.03 16.29 13.12 0.57 0.06 0.13 4/14/2009 11:40 11.83 0.00 54.63 1.76 16.99 13.22 0.46 0.04 0.12 4/14/2009 11:45 12.95 0.31 52.38 2.05 18.05 13.06 0.56 0.06 0.14 4/14/2009 11:50 13.03 0.29 53.06 1.78 17.65 13.20 0.44 0.04 0.10 4/14/2009 11:55 13.19 0.26 53.54 1.81 17.19 13.17 0.44 0.04 0.10 4/14/2009 12:00 13.39 0.00 51.76 2.22 17.85 13.30 0.59 0.07 0.09 4/14/2009 12:05 12.33 0.00 53.69 2.03 17.01 13.81 0.52 0.06 0.08 4/14/2009 12:10 12.79 0.00 53.41 1.91 17.12 13.56 0.46 0.05 0.08 4/14/2009 12:15 12.87 0.00 54.04 1.96 15.90 13.92 0.47 0.05 0.08 4/14/2009 12:20 12.51 0.00 54.39 1.78 16.77 13.43 0.41 0.04 0.07 4/14/2009 12:25 11.89 0.44 54.74 1.64 16.08 14.23 0.38 0.04 0.06 4/14/2009 12:30 13.09 0.82 50.67 2.54 18.23 13.35 0.63 0.10 0.07 4/14/2009 12:35 12.33 1.07 53.74 2.07 16.07 13.39 0.51 0.07 0.08 4/14/2009 12:40 13.14 0.19 53.02 1.86 16.63 13.93 0.51 0.05 0.12 4/14/2009 12:45 13.62 0.00 51.20 2.19 18.12 13.42 0.57 0.08 0.08 4/14/2009 12:50 12.74 0.00 53.69 1.78 16.51 13.94 0.41 0.05 0.06 4/14/2009 12:55 12.89 0.00 53.70 1.75 16.49 14.03 0.40 0.04 0.07 4/14/2009 13:00 13.95 0.00 52.16 1.71 17.97 13.13 0.39 0.04 0.09 4/14/2009 13:05 13.15 0.00 52.59 2.01 17.14 13.65 0.49 0.06 0.06 4/14/2009 13:10 13.94 0.00 49.29 2.60 18.32 14.05 0.65 0.10 0.09 4/14/2009 13:15 12.83 0.22 53.12 1.90 16.78 13.99 0.44 0.06 0.06 4/14/2009 13:20 12.71 0.57 53.56 1.74 17.37 12.87 0.41 0.04 0.08 4/14/2009 13:25 12.00 0.76 56.74 1.64 13.69 14.10 0.39 0.05 0.08 4/14/2009 13:30 11.44 3.18 56.78 1.69 14.18 11.62 0.37 0.04 0.05 4/14/2009 13:35 13.07 0.28 53.18 1.74 17.05 13.53 0.40 0.04 0.06 4/14/2009 13:40 13.55 0.27 52.80 2.14 16.70 13.29 0.48 0.05 0.05 4/14/2009 13:45 12.68 0.00 53.95 1.84 16.50 13.72 0.42 0.05 0.05 4/14/2009 13:50 13.32 0.00 52.59 1.90 17.11 13.57 0.43 0.06 0.09 4/14/2009 13:55 13.59 0.00 50.41 1.94 19.53 12.80 0.50 0.07 0.08 4/14/2009 14:00 13.55 0.00 52.15 2.10 17.12 13.47 0.51 0.07 0.07 4/14/2009 14:05 13.54 0.40 52.48 2.18 16.83 13.03 0.56 0.07 0.09 4/14/2009 14:10 13.29 0.46 52.49 2.10 16.76 13.35 0.51 0.06 0.09 4/14/2009 14:15 12.29 0.77 54.12 1.65 17.58 12.39 0.39 0.04 0.07 4/14/2009 14:20 12.50 0.59 54.09 1.74 16.29 13.37 0.40 0.05 0.06 4/14/2009 14:25 12.97 0.77 54.66 1.75 15.47 12.90 0.40 0.05 0.07
APPENDIX B
B.1 Orifice Plate Flow Meter Calibration.
The orifice plate flow meter with pressure transducer was calibrated with atmospheric air and a mass flow meter. The air first passed through the mass flow meter and then into the orifice plate. Mass flow readings were generated by the mass flow meter while voltage readings were generated by the pressure transducer. The voltage readings were calibrated to the flow readings by the use of a three parameter model,
Equation B.1.
Q = a (* VDC − b)c B.1
where Q = Predicted flow (SLM) c a = Constant = 495.483524 (SLM/VDC ) b = Constant = 0.9953318 (VDC) c = Constant = 0.53840789 VDC = Pressure transducer voltage (VDC)
Flow readings from 330 – 1000 SLM and the corresponding voltages from the pressure transducer are presented in Table B.1. These readings were used to generate the constants in Equation B.1. The use of these constants to predict actual flow is also presented in Table B.1. Finally, the standard error of this three parameter model is 6.8
SLM, Equation B.2.
Sum of squared residuals 1893 6. Standard Error = = = 8.6 SLM B.2 n - k 44 − 3
125 126 Table B.1: Orifice plate voltages, mass flow readings, and predicted mass flow readings. Orifice Plate Mass Flow Predicted flow using Residual e^2 (SLM 2) Pressure (VDC) Meter (SLM) Eq. B.1 (SLM (SLM) 1.4983 329.66 342.244 -12.584 158.37 1.5053 340.35 344.801 -4.451 19.81 1.5614 360.06 364.730 -4.670 21.81 1.5823 370.4 371.920 -1.520 2.31 1.5887 382.72 374.098 8.622 74.34 1.6608 398.49 397.923 0.567 0.32 1.6699 409.23 400.844 8.386 70.33 1.788 441.45 437.219 4.231 17.90 1.8418 459.04 452.954 6.086 37.04 1.8991 476.23 469.213 7.017 49.24 1.9599 491.5 485.953 5.547 30.77 2.0466 507.66 509.003 -1.343 1.80 2.0895 520.23 520.083 0.147 0.02 2.1748 548.61 541.534 7.076 50.07 2.2632 563.34 563.022 0.318 0.10 2.3888 590.19 592.396 -2.206 4.87 2.4473 600.63 605.659 -5.029 25.29 2.5963 636.75 638.367 -1.617 2.61 2.6932 650.59 658.888 -8.298 68.85 2.7137 662.71 663.159 -0.449 0.20 2.9405 707.89 708.934 -1.044 1.09 3.0978 720.01 739.247 -19.237 370.04 3.1491 733.21 748.904 -15.694 246.30 3.153 743.51 749.634 -6.124 37.50 3.1763 756.76 753.981 2.779 7.72 3.26 767.21 769.425 -2.215 4.91 3.3022 781.2 777.112 4.088 16.71 3.413 797.95 796.990 0.960 0.92 3.4503 809.13 803.587 5.543 30.72 3.5801 827.81 826.191 1.619 2.62 3.6188 838.15 832.828 5.322 28.33 3.6767 849.09 842.674 6.416 41.16 3.8885 870.37 877.883 -7.513 56.44 3.9331 881.41 885.143 -3.733 13.94 3.9442 892 886.942 5.058 25.58 4.0148 905.31 898.313 6.997 48.96 4.1467 917.43 919.232 -1.802 3.25 4.1637 930.14 921.898 8.242 67.92 4.342 951.37 949.478 1.892 3.58 4.5597 981.18 982.248 -1.068 1.14 4.6166 992.12 990.659 1.461 2.13 4.6952 1008.6 1002.179 6.421 41.23 4.9798 1043.2 1042.974 0.226 0.05 4.9363 1022.5 1036.828 -14.328 205.28
127 B.2 Sample Line Flow Meter Calibration.
The sample line flow meter was calibrated based on product gas composition determinations during startup experiments. This calibration was performed before the series of experiments for this thesis was performed, and was not re-calibrated further.
This flow meter is designed to measure nitrogen flow, but can be calibrated to measure the flow of different gases by the use of a correction factor, determined by Equation B.2, given in the flow meter manual.
a s + a s + ... + a s CF = .0( 3106 *) 1 1 2 2 n n B.2 a1d1cp 1 + a2 d 2cp 2 + ... + an d n cp n where CF = Correction Factor ai = Mole fraction of gas component i si = Molecular structure of gas component i 1.30 = Monoatomic 1.00 = Diatomic 0.94 = Triatomic 0.88 = Polyatomic di = Standard density (g/l) cp i = Specific heat (cal/g-C)
The values for the parameters used to generate the correction factor for this flow
meter are presented in Table B.2.
128 Table B.2: Sample line mass flow meter parameters for correction factor determination. Numerator Denominator Gas Mole Structure Component d *cp a *s a *d *cp fraction (a ) (s ) i i i i i i i (i) i i Hydrogen 0.1405253 1.00 0.3073681 0.1405253 0.043192994 Nitrogen 0.5028475 1.00 0.310625 0.5028475 0.156197005 Methane 0.0182604 0.88 0.380952 0.016069152 0.006956336 Carbon 0.29002363 0.069382576 1.30 0.311 Monoxide 0.2230951 Carbon 0.103887906 0.041133627 0.94 0.3959424 Dioxide 0.1104016 Sum 0.9951299 1.053353488 0.316862538
From these parameters, a correction factor of 1.0325 was determined.
1.05335348 8 .1 0325 = .0( 3106 *) 0.31686253 8
APPENDIX C
C.1 Estimating Product Gas Temperature Profile for First Two 13% MC Runs.
The 13% MC experiments were conducted first, and the thermocouple measuring
the product gas temperature was incorrectly installed for the first two experiments. The
resulting lower temperature profiles of these experiments compared with the final eight
experiments are shown in Figure C.1.
50 45 5.8% Run 1 40 5.8% Run 2 35 5.8% Run 3 30 25 13% Run 1 20 13% Run 2 15 13% Run 3 10 13% Run 4 5 22% Run 1
ProductGas Temperature (C) 0 22% Run 2 0 100 200 22% Run 3 Run Time, Min
Figure C.1: Product gas temperature profiles for 10 experimental gasifier runs using Douglas Fir woodchips as fuel.
129 130 A polynomial fit to the temperature profiles of the final two 13% MC experiments was used to estimate the temperature profile of the first two 13% MC experiments, which is shown in Figure C.2 and Table C.1.
50
40
30
20 y = -0.0005x 2 + 0.2244x + 17.663 10 R2 = 0.7729 0 Product Gas Temperature (C) Temperature Gas Product 0 50 100 150 200 250 Run Time, Min
Figure C.2: Polynomial fit of the product gas temperature profiles of the 3 rd and 4 th 13% MC experiments.
131 Table C.1: Estimated product gas temperature profile for the first two 13% MC experiments, using a polynomial fit to the product gas temperature profiles of the final two 13% MC experiments. Efficiency Interval Estimated Product Gas Run Time (min) Temperature (ºC) 0 17.7 5 18.8 10 19.9 15 20.9 20 22.0 25 23.0 30 23.9 35 24.9 40 25.8 45 26.7 50 27.6 55 28.5 60 29.3 65 30.1 70 30.9 75 31.7 80 32.4 85 33.1 90 33.8 95 34.5 100 35.1 105 35.7 110 36.3 115 36.9 120 37.4 125 37.9 130 38.4 135 38.8 140 39.3 145 39.7 150 40.1 155 40.4 160 40.8 165 41.1 170 41.4 175 41.6 180 41.9 185 42.1 190 42.2 195 42.4 200 42.5 205 42.7