Condensation of Steam in a Packed Column in Direct
CONDENSATION OF STEAM IN A PACKED
COLUMN IN DIRECT CONTACT WITH
IMMISCIBLE LIQUIDS
by
VIRENDRA CHANDRA RAI B.Sc, University of Allahabad, India, 1958 M.Sc. (Maths.), University of Allahabad, India, I960 Sc. (Chem. Eng.), Banares Hindu University, India, 19&4
A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF APPLIED SCIENCE
in the Department of CHEMICAL ENGINEERING
We accept this thesis as conforming to the required standard
THE UNIVERSITY OF BRITISH COLUMBIA
APRIL, 1966 ii
ABSTRACT
A packed condenser and the auxiliary equipment were designed, built and tested for the condensation of steam in direct contact with
Aroclor 1242 and 1248, which are commercial heat transfer agents and are immiscible with water. The co-current flow of steam and liquid, through a four inch inside diameter column packed with three-eighth inch ceramic Raschig rings, was studied. The packing heights used in the condensation of steam were estimated from the liquid temperature profile in the column. The heights of the transfer units for condensation and the average volumetric overall heat transfer coefficients were cal• culated. The height of the transfer unit for condensation was found to be affected largely by the mean viscosity and the flow rate of the liquid.
Two empirical equations have been developed to describe the results of this study.
HCU = F ( ^JL_>" where n = 1. 10 for Aroclor 1242 and n = 1. 16 for Aroclor 1248
is mean viscosity of the Aroclor in centipoise. For Aroclor 1242, ^ F= 0.0535+ 8.90xl0" L when L ^..2290 _ 5
and F =-0. 0737 + 6. 44 x 10 L, when L > 2290.
For Aroclor 1248, F = 0. 02765 + 1. 244 x 10"5L.
L is superficial mass velocity of the Aroclor in lb /hr. ft iii
ACKNOWLEDGEMENTS
The author is highly indebted to Dr. K. L. Pinder for his constant guidance, help and encouragement during the entire course of this project.
The author also wishes to extend his thanks to the personnel of the Chemical Engineering Workshop and the Stores for their parte in building the equipment for this research.
Financial assistance was received from the National Research
Council of Canada and from the University of British Columbia in the form of U. B. C. Graduate Fellowship, for which the author is really grateful. iv
TABLE OF CONTENTS
Page
CHAPTER ONE - INTRODUCTION 1
A. DIRECT CONTACT CONDENSATION (GENERAL) 3
1. Historical 3 2. Mechanism 4
B. DIRECT CONTACT CONDENSATION WITH SAME LIQUID 5
C. DIRECT CONTACT CONDENSATION WITH IMMISCIBLE FLUID 6
D. CONDENSATION WITH AN IMMISCIBLE LIQUID
IN PACKED COLUMNS 8
CHAPTER TWO - AIMS AND INITIAL PLANS 15
CHAPTER THREE - APPARATUS 22
A. PACKED CONDENSER . 22
B. SEPARATOR-COOLER 29
C. SURGE TANK , 32
D. LIQUID PUMP 33
E. PARTS FOR THE PREPARATION OF STEAM 33
F. INSTRUMENTS 35 1. Orifice. meter 3 5 2. Pressure Gauge 37 3. Temperature Measuring'Instruments 37 4. Twelve Point Switch 37 5. Millivolt Potentiometer 38
CHAPTER FOUR - EXPERIMENTAL PROCEDURE 42
A. DETERMINATION OF SEPARATION TIME FOR WATER FROM AROCLORS 42
B. CALIBRATION OF THERMOCOUPLES 43
C. CALIBRATION OF SURGE TANK LEVEL INDICATOR 44 D. CALIBRATION OF ORIFICE , METER 45
E. DETERMINATION OF HEAT LOSSES 46
F. DETERMINATION OF STEAM QUALITY 47
G. MAIN EXPERIMENT 48
H. CALCULATION METHODS 51
1. Height of Packing Used 51 2. Average Liquid Temperature and Temperature Driving Force 53 3. Number and Height of Condensation Units 54 4. Heat Balance 54 5. Volumetric Heat Transfer Coefficient 55 6. Reynolds Number 55
CHAPTER FIVE - RESULTS AND DISCUSSION 56
A. RESULTS • 56
1. H. C. U. vs. Arithmetic Mean Temper• ature 57 2. H. C. U. vs. True Mean Temperature 57 3. H. C. U. vs. Superficial Mass Velocity of Aroclor 62 4. H. C. U. vs. Reynolds Number 62 5. Ua vs. True Mean Temperature 67
B. REPRODUCIBILITY OF RESULTS 67
C. ACCURACY OF RESULTS 75
D. COMPARISON WITH LITERATURE VALUES 78
E. BEST EQUATIONS FITTING THE EXPERI• MENTAL RESULTS 84 F. COMPARISON OF THE RESULTS FOR AROCLOR 1242 AND 1248 86
CHAPTER SIX - CONCLUSION AND RECOMMEN• DATIONS 88
NOMENCLATURE 91
BIBLIOGRAPHY 93
APPENDIX A - BASIC DESIGN CALCULATIONS 9 5
A. PACKING REQUIREMENT 9 5 Page
B. AROCLOR FLOW RATE 95
C. STEAM RATE 96
D. SEPARATOR COOLER 96
E. SURGE TANK 98
F. LIQUID PUMP 99
G. FLOW METER '99
APPENDIX B - CALIBRATIONS 101
A. THERMOCOUPLE AND THERMOMETER CALIBRATION 101
B. CALIBRATION OF SURGE TANK LEVEL INDICATOR 104
C. CALIBRATION OF ORIFICE .METER 106
D. DETERMINATION OF HEAT LOSSES 111
APPENDIX C - RAW DATA 114
APPENDIX D - PROCESSED DATA AND RESULTS 12 3
APPENDIX E - SAMPLE CALCULATIONS 133
A. CALCULATION OF EXPERIMENTAL RESULTS 13 3 1. Height of the Packing 133 2. Number and Height of Condensation Units 133 3. Superficial Mass Velocity of Aroclor 135 4. Aroclor Mean Temperature 135 5. Heat Balance 136 6. Average Temperature Driving Force and TJ-a ' 138 7. Reynolds Number 139
B. CALCULATION OF HCU FROM LACKEY'S AND WILKE'S EQUATIONS 140
C. BEST EQUATIONS TO FIT THE EXPERI• MENTAL RESULTS 142 vii
LIST OF TABLES
'.VJSEable ' Page
1. Some Properties of Aroclor - 19
2. Calibration Data for Thermometer and Thermo• couple No. 1 102
3v Calibration Data for Surge Tank Level Indicator 104
r 4. Orifieeimter Calibration Data for Aroclor 1242 106 /
5. Orifice meter Calibration Data for Aroclor 1248 109
6. Heat Losses Data for Aroclor 1242 111
T. Heat Losses Data for Aroclor 1248 111 r 8. Height of the Thermocouples above the Packing Support 114
9. Steady State Thermocouple Readings (Aroclor 1242) 115
10. Miscellaneous Data (Aroclor 1242) 117
11. Steady State Thermocouple Readings (Aroclor 1248) 119
12. Miscellaneous Da£a (Aroclor 1248) 121
13. Processed Data (Aroclor 1242) 123
14. Processed Data (Aroclor 1248) 125
15. Results (Aroclor 1242) 127
16. Results (Aroclor 1248) 129
17. Reynolds Numbers (Aroclor 1242) 131
18. Reynolds Numbers (Aroclor 1248) 132
19. Values of F, Aroclor 1242 144
20. Values of F, Aroclor 1248 144 viii
LIST OF FIGURES
Figure Page
1. Front View of Apparatus 23
2. Schematic Flow Diagram 24
3. Condenser Assembly 2 5
4. Thermocouple Shields 28
5. Separator-cooler Assembly 30
6. Orifice meter 36
7. Supporting Panel With Main Parts of the
Apparatus 39
8. Sample Temperature Profile in the Condenser 52
9. Results: HCU vs. A. M. T. , Aroclor 1242 58
10. Results: HCU vs. A. M. T. , Aroclor 1248 59
11. Results: HCU vs. T. M. T. , Aroclor 1242 60
12. Results: HCU vs. T. M. T. , Aroclor 1248 61
13. Results: HCU vs. L, Parameter A. M. T. Aroclor 1242 63 14. Results: HCU vs.L, Parameter A. M. T. Aroclor 1248 64
15. Results: HCU vs. L, Parameter T. M. T. Aroclor 1242 65
16. Results: HCU vs. L, Parameter T. M. T. Aroclor 1248 66
17. Results: HCU vs. Re, Parameter A. M. T. Aroclor 1242 68
18. Results: HCU vs. Re, Parameter A. M. T. Aroclor 1248 69 Results: HCU vs.Re, Parameter T\ M, Tr Aroclor 1242
Results: HCU vs. Re, Parameter T. M. T. Aroclor 1248
i
Results: T3*avs. T.M. T. Aroclor 1242
Results: 10=a vs. T. M. T. Aroclor 1248
Heat Balance, Qi^vs. Q^, Aroclor 1242
Heat Balance, vs. Q^, Aroclor 1248 Comparison of Results (HCU vs. Absolute value of T. M. T. ) for Aroclor 1248
HCU vs. Absolute value of T. M. T., Aroclor 1242
Effect of L on F
Calibration Curve for Thermocouple No. 1
Volume - Level Curve for Surge Tank
Orifice meter Calibration Curves for Aroclo 1242
Orifice, meter Calibration Curves for Aroclo 1248
Heat Losses from Condenser for Aroclor 1242
Heat Losses from Condenser for Aroclor 1248 CHAPTER ONE
INTRODUCTION
Condensation, a unit operation in itself, forms an essential
part of many unit operations s'^ch as evaporation, distillation, sub•
limation etc. , which are quite common in industry. The economy
of a condensing unit plays an important role in determining the
capital and the operating costs of a process. Furthermore, all
the condensation techniques have their own merits and demerits
which may recommend their application to a particular process
or may forbid it.
Basically, there are two types of condensers (the name used henceforth for the equipment performing the condensation operation):
surface condensers and direct contact condensers. In a surface
condenser the vapour to be condensed is separated from the cooling
fluid by a solid surface. The solid surface, usually metallic,
conducts the heat from the vapour to the cooling fluid. On the other hand, a direct contact condenser brings the vapour into direct contact with the cooling fluid and thereby allows the direct exchange of heat. 2
Direct contact condensation may be at .be .achievedby mixing, the vapour with the same liquid as the condensate or with a liquid immiscible with the condensate.
The direct contact condensers have the following advantages over the surface condensers:
1) No reduction in heat transfer due to scaling.
2) Close temperature approach due to high heat transfer
coefficient in direct contact.
3) Corrosion problem is not serious.
4) Simple equipment and hence low initial cost.
The direct contact gives high coefficients of heat transfer for condensation due to the fact that the mechanism in this case is most likely close., to that of drop-wise condensation on solid surfaces. As mentioned by Ruckenstein and Metiu (1) drop-wise condensation occurs on a solid surface:
i. "at large undercoolings when the condensing surface
has numerous active centres, so close as to form a
continuous film of condensate. This film grows, reaches
a critical thickness and then breaks into drops. Drops
then grow through coalescence. " The case of direct
contact condensation is analogous to this, especially 3
at large temperature differences. The condensing "surface"
(cooling fluid) provides large "undercooling" of the vapour
and there is always plenty of free surface available.
ii. "at small undercoolings when the condensing surface has
only few active centres on which the drops are formed. "
The same is the case when the temperature of the cooling
Fluid closely approaches the temperature of the vapour.
The coefficients of heat transfer in the dropwise condensation are much higher than in the filmwise condensation. In the dropwise
2 o condens ation, coefficients of more than 50, 000 BTU/hr. , ft. , F have been reported (2) .
A. DIRECT CONTACT CONDENSATION (GENERAL)
1. Historical
Direct contact condensation was first applied in the steam engine of Watt and Newcomen in the early 18th century. The con• densation of exhaust steam was accomplished by introducing a jet of liquid water into the cylinder of the engine after the power stroke. The steam condensed on the water jet and left the cylinder on the return stroke. It was observed that the lower the exhaust pressure, the higher is the thermal efficiency of condensation and of the engine. This led to the adaptation of the barometric leg and vacuum pump. Since that time the direct contact condenser has been widely used in steam power plants and in many evaporative processes. 4
2. Mechanism
The condensation in direct contact is achieved through the following three steps (3):
1) Movement or diffusion of vapour to the liquid surface
(interface).
2) Heat transfer from the vapour to the liquid at the interface
resulting in the condensation.
3) Heat transfer from the interface to the bulk of the liquid.
The diffusion of the vapour to the liquid surface presents the controlling resistance and, therefore, although the condenser is meant for heat transfer, it is designed primarily on the principles of fluid flow and mass, transfer from the vapour phase to the liquid phase (3).
In direct contact, the condensation of vapour is achieved by intimate mixing of the vapour with the liquid. The amount of vapour that can be condensed by a definite amount of liquid may be determined by a simple heat balance. The condensate may be re• moved at any predetermined temperature and the cooling fluid may be heated to any desired temperature, theoretically, by regu• lating the.liquid flow rate. But the rate at which the vapour is actually condensed,is determined by the overall rate of diffusion 5
or the coefficient of mass transfer, by the area of the condensing surface and by the temperature difference.To study the performance of condensers, the rate of diffusion may, in turn, be represented by an overall average heat transfer coefficient. The performance of the condenser can be most easily improved by increasing the area of condensing surface (by reducing the drop size or by using a packed column) or by increasing the temperature difference.
B. DIRECT CONTACT CONDENSATION WITH SAME LIQUID
Direct contact condensation of steam with water is quite common in industry. Various types of condensers have been patented for the job. Most of them are based on the condensation of steam on a single or a number of fast flowing water jets. Coons (3) has given a good account of direct contact condensers. A lot of work has been done in this field by a number of investigators. Recently some work has been reported on condensation of steam on laminar water jets and water sheets (4, 5). The condensation of vapours in two phase flow with the condensate has also been studied (21).
Besides the condensation of steam with water, the dehumidi- fication of gases is also achieved by direct contact condensation
(6, 22). The only difference lies in the fact that in condensing steam, the vapour phase contains only a small amount of noncondensible 6
gases while in the other case, it contains only a small amount of condensible vapour.
C. DIRECT CONTACT CONDENSATION WITH IMMISCIBLE FLUID
Condensation with an immiscible fluid is particularly useful where the condensate is the end product and is too costly to be used in bulk for condensation. The literature contains very little on the direct contact condensation of a vapour with a liquid which is immiscible with the condensate. This absence of published infor• mation is really not too surprising. The method of condensing a vapour with an immiscible liquid is very simple and has been of common use in industry (7). In fact the direct condensation processes for which the economics have been studied, show enough advantages over the conventional surface condensers, that they are kept secret (7).
There are three basic processes for direct contact condensation;
1) One stream can be injected into a high velocity, turbulent
stre am of the other fluid. For example the vapour can
be injected into the throat of a venturi through which the
liquid is flowing.
2) One stream can be injected into the other at relatively
low velocity as in a sieve plate column . 3) Both streams can be brought into contact with each other
in a packed column or a spray column which artificially
increase the surface area of contact.
Lackey (7) has studied these three processes theoretically and
has outlined the design procedure and compared their economics. He
reports the following total annual costs for a heat duty of 10 million
BTU/hour.
For venturi in series $70, 900
For venturi in recirculation $71,700
For direct injection (in a column) $49, 700
For packed column $39, 800
For surface condenser $60, 800
Shao Chio Hu (.8) in 19 56, was the first to publish a method for
designing a packed tower for direct contact condensation of gasoline.
Wilke, Cheng et al. , (9, 10) have studied a packed column for direct
contact condensation of water vapour with an immiscible liquid,
to be used in the desalination of sea water. Harriott and Wiegandt
, (11) in a paper entitled "Countercurrent Heat Exchange with Vapor•
izing Immiscible Transfer Agent" have reported experimental work
on the condensation of a vapour with water (the condensate only
partially miscible with water) in a packed column and in a sieve plate
column. In spite of a higher volumetric heat transfer coefficient 8
in a sieve plate column (400, 000 BTU/hr. , ft. , °F as against
3 o
150, 000 BTU/hr. , ft. , F for the packed column) they recommend the use of a packed column because a closer temperature approach could be obtained. due;.to'bl'e.ss backmixing in packed column.
The condensation of a vapour by mixing it with a cool gas, the gas being immiscible with the condensate, also fits into the category of direct condensation. This method is quite common in industry for the recovery of certain organic compounds (eg. phthalic anhydride) from the mixture of air 'and their vapour.
Ciborowski and Surgiewicz (12) have studied this method for the recovery of phthalic anhydride and found that the yield is affected by the vapour content of the inlet gas, by the ratio of the cooling gas and hot gas flow rates and by the individual flow rates. The same were the findings of Levine and Friedlander (13) while con• densing glycerine vapour by mixing it with cold air.
D. CONDENSATION WITH AN IMMISCIBLE LIQUID IN PACKED COLUMNS
From the works of Lackey (7) and Harriott and Wiegandt (11), as discussed above, it is clear that a packed column appears to be the most promising and economical equipment for direct contact condensation of a vapour using an immiscible liquid for heat transfer.
Although this method has two drawbacks, ie. the high circu• lation rate of liquid hence the high pumping cost, and the large 9
volumes of liquids to be separated, it is expected to be more
economical than the other conventional methods. This method
of condensation is very well suited to many industrial applications
such as sea water desalination by the compression evaporation
process (14) or by the freezing process, steam distillation, simple
fractional distillation and sublimation purification.
The design method for such condensers as proposed by
Hu (8) is in brief: *
1) Calculation of heat and material balances.
2) Calculation of tower diameter from usual flooding
characteristic curves of Sherwood et. al. (15). Hu
recommends a diameter slightly larger than that for
flooding.
3) Calculation of HTU for liquid film from \rn 0. 5 HTU = f r) "-•
The values of fi and ^ are as given by Sherwood and
Holloway (16). The Schmidt number Sc is calculated
using the diffusivity D obtained by Wilke's correlation L curve (17).
4) Calculation of NTU from
The equations quoted here were obtained from reference 7- They are dimensionally inconsistent. The definition of Lewis number is not correct and also the division of temperature in Fahrenheit or Centigrade scale by temperature difference is not justified. ha v t L
and NTU ha . v h (Le) 2/3 where Le (Lewis No.) = k
ft V 5) Calculation of tower height from H = HTU x NTU
In the last step, the HTU is for the liquid film while the NTU is based on the properties of vapour. Thus the calculated tower height is basically incorrect. Moreover, Hu's design is for con• densing gasoline vapours which carry a considerable amount of noncondensible gases. He assumes the liquid film resistance to be controlling throughout the length of the column. This is quite acceptable in the lower sections of the column where the vapour phase is very rich in gasoline vapour. Near the top of the column, the vapour phase becomes very lean in condensible vapour, so much so that the gas phase resistances cannot be neglected.
The design method of Lackey (7) involves the calculation of
HTU for heat transfer from that for mass transfer using
HT MT 11
(HTU ) in turn is to be estimated from Sherwood and V MT Holloway's data (16) for 0 - HO system using the equation
HTU 0.556-0. 152 log L
HTU L(w)
His NTU is directly derived from the heat balance on a differential
element of tower height
NTU ln
Wilke et al.,(9) have done experimental work on the con•
densation of steam with Aroclor 1248 in a one foot diameter tower packed with one inch Raschig rings. The experiment was
carried out at nearly atmospheric pressure and the value of HTU 2 was calculated and plotted against the liquid flow rate lb/hr, ft
on a log-log graph. They have also calculated and plotted the
(HTU)Tr_ from the Sherwood and Holloway's data (16) on 0 - H 0 HT 7 x 2 2 system using the equation
This equation is essentially the combination of the two equations used by Lackey (7), given above, except for the major difference in the power on the viscosity ratio. A check on the calculations showed 12
that the power 0. 155 as given by Lackey was correct. The other value
of the exponent is a modification in this equation. The experimental
results of Wilke et. al. (9), however, showatrend similar to those
calculated from mass transfer data, but are not in close agreement
with them. The calculated values are always lower than the experi•
mental ones. The difference is up to 15% in HTU. Moreover, they
did not find any definite effect of liquid temperature on HTU.
Harriott and Wiegandt (18) also have developed a method for
calculating the overall heat transfer coefficient for condensation
in a packed column from the published mass transfer data of Sher- w ood and Holloway (16). The method is
1) Calculation of HTU for the given liquid flow rate L at.
the operating temperature and for the packing properties .
2) Calculation of mass transfer coefficient from
kLa = VHTUX/O
3) Calculation of diffusivity of 0^ in HO at operating
temperatures .
4) Calculation of Ua si ha from
ha = j Cr-/>~~k k a V D J-J
This method was used to obtain the values which were compared with 13 the experimental results from their work (11). The experimental points are such that any straight line relationship may be imagined to be satisfied. The theoretical line is certainly not the best fit of the experimental data.
Thus it is clear that there is.no straight forward, and accurate procedure for designing a packed column for direct condensation using an immiscible liquid. The published design procedures proposed by Hu (8), Lackey (7), Wilke (9) and by Harriott and Wieg- andt (18), are all based on the calculation of a heat transfer coeffi• cient or height of heat transfer unit from Sherwood and Holloway's
(16) data on 0_, desorption from water. The method and the comput• ations involved are quite complicated. Moreover, the procedure is reportedly supported by the experiments of Wilke et al. (9) and of Harriott and Wiegandt (11). Neither of these studies were done for more than one system or for a series of operating conditions.
As mentioned before, these experimental results only show a trend which is similar to the theoretical results. The values are quite different. The values of HTU predicted from mass transfer data are always lower than the experimental ones. The predicted values of Ua are similarly higher than the experimental ones. Therefore, any condenser designed with the values of HTU or Ua predicted from mass transfer data using the method of Hu (3), Lackey (7),
Wilke et. al. (9) or Harriott and Wiegandt (18) will be under-de signed. 14
Considering all these facts it was decided to study heat transfer during condensation in a packed column, using immiscible, commercial heat transfer agents. The aim was to find some direct correlation,between the heat transfer coefficient (or height of transfer unit for condensation, called HCU henceforth) and the physical properties of the liquid, the vapour and the packing,and the operating conditions. CHAPTER TWO
AIMS AND INITIAL PLANS
This work was started to investigate the performance of a packed column in the direct contact condensation of steam using commercial heat transfer agents immiscible with the condensate.
After having decided in favour of an extensive study of a packed condenser, it was necessary to investigate experimentally whether or not this line of attack was going to yield any worthwhile infor• mation. As an initial investigation in this field this study set forth:
1) To design a packed condenser and auxilliary testing
equipment.
2) To build it according to the design.
3) To operate the equipment .
4) To look for the operational troubles and faults in the
equipment .
5) To operate the equipment with steam and two different
liquids and see if it gives any reproducible trends in
the results. 16
In order to achieve these aims, it was necessary to obtain or design:
1) A source of steam of known heat content and air content ,
2) Two commercial heat transfer agents, immiscible with
water, and with a boiling point much above that of water,
3) Some means of measuring the rate of condensation of,
steam ,
4) Some means of measuring and changing the liquid flow
rate and temperature, and
5) A packed column with some means for varying the
height of packing to be used for condensation.
The supply line from the boiler house contains steam which is liable to be wet and contaminated with dust particles. In the begin• ning the installation of a small boiler to generate steam was con• sidered but later this idea was dropped due to the fact that the steam quality would still be unknown and moreover, the operation of a boile and of the condensation equipment may be too much for one man without extensive automation. It was decided, therefore, to use the steam from the supply line after filtering it. The heat content and the air content were to be determined experimentally.
The heat content or the dryness fraction of wet steam could be easily measured with a throttling calorimeter if the steam were 17
not too wet, otherwise some means for drying the steam by heating it was to be designed. In case that also did not work, the heat content of steam can be determined by condensing it in a known quantity of water. The air content of the steam can be estimated by measuring the volume of air and the condensate collected in a definite interval of time.
Easily available commercial heat transfer agents which are immiscible with water are the Aroclor compounds manufactured by
Monsanto Chemical Company. The properties of the heat transfer agents desired in this type of work are:
1) it should be immiscible with water
2) the solubility of water in it, if any, should be nearly
constant at all temperatures
3) it should have a boiling point much above the condensation
temperature of experimental steam
4) it should have a density quite different from water
5) it should not be viscous at operating temperatures
6) it should have a low pour point
7) it should not be corrosive
8) it should not be poisonous
9) it should not be inflammable
10) it should have a low evaporation loss at operating
temperatures. 18
All of these properties are very well satisfied by Aroclor
1242 and 1248, as can be seen in Table 1.
To measure the rate of condensation of steam, the condensate must be separated from the Aroclor. The Aroclor separated from the condensate can be recirculated after being cooled.
The measurements of liquid flow rate and temperature are essential as their values definitely affect the rate of heat transfer.
It was decided to design and build an orifice meter for the flow measure• ment of the liquid. For the measurement of temperature, it was decided to use Copper- constantan thermocouples due to their accuracy and the need for remote temperature reading in the column.
Because of the length of run necessary to attain steady state in such experiments (24), it was decided to use the heat transfer agent in a closed circuit. The heat removalfrom the liquid stream would require a cold water heat exchanger. The temperature of the liquid could be varied by regulating the cooling water flow rate.
The packing material to be used in the packed condenser should not react with the streams, should be able to stand the operating conditions and should provide a large surface area per unit volume. In this work, the streams, which are steam, Aroclors and the water, do not restrict the use of a particular type of packing. 19
TABLE 1
Some properties of Aroclor 1242 and 1248 (19)
Property Aroclor 1242 Aroclor 1248
Acidity, mg. KOH per gm 0.010 0. 010
Density, gm/ml . @ 50°C 1.350 1.430 •
Distillation range, °C 325-366 340-375
% Evaporation loss in 6 hours @ 100°C 0.0 -0.4 0.0 -0.3
Open cup Flash Point, °C , 176 - 186 193 - 196
Pour Point, °C -19 -7
Viscosity, Saybolt Universal secs @ 50°C 58 85
Heat capacity, c'al/gm, °C @ 50°C 0.30 0.28
Solubility in water insoluble insoluble
Penetration in copper, cm /day -5 -4 @ 125°C N. A. 10 - 10
Penetration in brass, cm /day @ -5 125°C N. A. 10
N. A. Not available in reference 19 20
All the other requirements are fulfilled by most of the industrial packings. It was decided to use a column packed with ceramic
Raschig rings or Berl saddles which are most widely used in industry. The use of a highly conductive packing was left for a later study.
The natural direction of flow of steam in contact with liquids is upwards, hence it was decided to feed the steam at the bottom of the packed column. The Aroclors,being heavier than water, cannot be fefl to the top of the column due to the fact that the condensate,being lighter than Aroclor, will rise to the top of the; column. Thus the water will collect in the column itself and will not come out with the Aroclor from the bottom of the column until a very high flow rate is reached. Therefore, it was decided to feed the Aroclor also at the bottom of the column and allow the Aroclor and water to leave from the top of the column.
The last problem to be considered at this stage was to find some means to vary the height of packing or restrict its use for the condensation of steam. A simple way would be to estimate the height of packing used for condensation from the temperature profile of the Aroclor in the column. As the steam rises in the column, it condenses and the temperature of the liquid increases. At the point 21
where the condensation of steam is complete, the liquid should have a maximum temperature and after that it should drop gradually due to heat losses. The location of the point where liquid temperature is maximum should be the height of packing used for the condensation of steam and for cooling the condensate to the Aroclor temperature.
It was decided to try this technique by installing a number of copper- constantan thermocouples in the column to read the liquid tem• perature. CHAPTER THREE
APPARATUS
Figure 1 shows a front view of the apparatus. The various parts of the apparatus and the direction of flow of different streams are shown in Figure 2. The apparatus will be, described under six separate headings.
1) Packed Condenser
2) Separator-cooler
3) Surge tank
4) Liquid Pump
5) Parts for the preparation of steam
6) Instruments
A. PACKED CONDENSER
This is the main part of the apparatus. Here the steam comes in contact with the cooling liquid and condenses. The complete assembly of the column is shown in Figure 3.
The column is made of an eighteen inch long section of four inch inside diameter, pyrex glass pipe, flanged at both ends. The ends are closed with two, three quarters of an inch thick brass plates 23
Figure 1 Front View of Apparatus LEGEND FOR FIGURE 2 & 7
C Cyclone GV Gate valve NV Needle valve O Orifice PC Packed condenser P. G- Pressure gauge P. R. Pressure regulating valve, 0-20 psig P. R. V Pressure regulating valve, 0-25 psig SC Separator-cooler ST Surge tank T Steam trap Y- F. Y - filter Figure 2 Schematic Flow Diagram 25
SCALE HALF FULL SIZE
Figure 3 Condenser Assembly 26
Figure 3 Condenser Assembly 27
which are bolted to the flanges. Both end plates have conical depression on their internal surfaces. The top depression is to allow the removal of last drop of condensate with the cooling liquid while the bottom depression is to allow complete draining of the column whenever required. A perforated brass plate, one sixteenth of an inch thick, just above the bottom plate supports the packing $ and allows the free flow of liquid and steam.
All the pipe fittings are made to the end plates of the column.
The inlet and the outlet for the liquid are in the centres of bottom and top plates respectively. The steam inlet is on one side ofthe bottom plate. Two, one eighth inch outside diameter copper tubes, which inject the steam into the packing in two^different directions through the perforated plate, are brazed to the steam inlet connection.
A quarter inch stop cock is provided in the top plate to remove air from the column.
Ten capper - constantan thermocouples are installed in the column at intervals of approximately two inches. These thermo• couples are fitted in the bottom plate using one eighth inch O. D.
Imperial pipe fittings. Each thermocouple is bent to a horizontal position and points towards the centre of the column. Aluminum
Thvo «igf_t Sscb ceramic Ratcfeig sings. • 1 ro co V/j
J SCALE-8XFULLSIZE
MATERIAL-ALUMINIUM
Figure 4 Ther mo couple Shield 29
shields are attached to the hot junctions of the thermocouples to protect them from the contact of rising steam bubbles (Fig. 4) while still allowing free flow of liquid. Three eighth inch diameter brass discs with a one eighth inch hole in the centre are also fixed on the vertical sections of all thermocouples which are longer than four inches to reduce the possibility of channeling along the thermo• couple.
The column and the end plates are insulated with three layers of one inch glass wool blanket. On top of the glass wool, corrugated card board is tied in position to secure the insulation.
B. SEPARATOR-COOLER
The purpose of the separator-cooler is to separate the water from the Aroclor and to cool the latter for recirculation. A complete drawing of this column is given in Figure 5.
The separator-cooler consists of two sections of six inch internal diameter, pyrex glass pipe (Appendix A), bolted together as shown in Figure 5. The lower section is six inches high while the upper section tapers at a height of four inches, to four inches internal diameter. The total height of this section is nine inches.'.; The conical shape of the upper sections helps in the removal of separated condensate. The ends of the column are closed with brass end plates. 30
SCALE- 3/8 FULL SIZE
Figure 5 Separator-Cooler Assembly c.-BOTTOM PLATE
Figure 5 Separator-Cooler Assembly The top plate is indented on the inside to allow the removal of the last drop of water. The column stands on four flange bolts extended to make four legs.
Inside the column about twenty feet of three-eighth inch out• side diameter copper tube are provided as a cooling coil. The ends of the coil are connected through the Jbottbm plate.
All the pipe fittings are made to the top and bottom plates. The inlet for the mixture of Aroclor and water is a half inch outside diameter copper tube which extends aboutfour inches into the column through the top plate. The reason for the extension of this tube into the column is to avoid contacting the separated water with the hot incoming Aroclor. The extension was restricted to six inches to allow one foot of column height for separation (Appendix A).
A 1500 watt emersion type electric heater with built in thermo• stat was also installed in the column for preheating the liquid at the beginning of the experiments.
C SURGE TANK
This tank was designed to hold the Aroclor for recirculation.
It is a rectangular tank one foot long, six inches wide and six inches deep, which is made of one thirty second of an inch thick galvanized iron sheet, and is open to the atmosphere at the top. (Appendix A). All the pipe fittings are made to brass pieces soldered on to the sides and on to the bottom of the tank. A six millimeter outside diameter, vertical glass tube is connected to a side of the tank through an elbow. This glass tube indicates the liquid level in the tank, which can be read from a centimeter scale attached to the tube. The tank is also provided with about ten feet of three eighth inch outside diameter copper tube which can be used as a cooling coil if required.
D. LIQUID PUMP
An Eastern Industries gear pump, model GW-1, driven by a quarter horsepower General Electric, 115 volts, single phase alternating current motor, circulates the Aroclor through the system
(Appendix A). It sucks the Aroclor from the surge tank and cir• culates it through an orifne.meter to the packed condenser or through a pressure regulating valve (1 to 2 5 psig) back to the surge tank at any desired rate up to one gallon per minute. The elevated position of the surge tank keeps the pump primed at all times.
E. PARTS FOR THE PREPARATION OF STEAM
The steam in the main header is at a gauge pressure varying from fifty to sixty pounds per square inch and is liable to be wet and contaminated with dust. Before being fed to the condenser, it is passed through a series of purification steps as shown in Figure 2. 34
The steam from the main header enters a cyclone through a gate valve. The downcomer of the cyclone is connected to a steam trap for the continuous removal of water. A major part of the moisture and dust is removed in this cyclone. The steam then passes through a Y-filter and a pressure regulating valve. The filter removes the remaining solid dust particles from the steam, while the pressure regulating valve regulates the down stream pressure between zero and twenty pounds per square inch gauge.
Then the steam passes, through another cyclone and a needle valve, before entering the condenser. A branch line with a needle valve > shut off, connected just after the second cyclone is used as the sampling line for testing the quality of the steam.
It was first attempted to measure the quality of the steam with a throttling calorimeter. These tests revealed that the steam after the second cyclone was too wet to show any superheat on expansion to the atmospheric pressure. An electrically heated packed bed
(packed with copper wool and nickel shots) was then designed to dry the steam. The power input to the heater was controlled with a
Variac. An'iim.mersion type water heater, rated at 1000 watts at 2 30 volts,was used with 11 5 yolts alternating current supply to provide the maximum requirement of about 2 50 watts needed for drying the steam. The heater was installed in a one foot long, two inch nominal 35
diameter steel pipe. This arrangement did not work. The steam apparently channeled through the packing without enough heat ex• change. It was therefore decided to measure the steam quality calorimetrically by condensing it in a known quantity of water.
F. INSTRUMENTS
The instruments used with this apparatus are
1) An orifice .meter
2) Four pressure gauges (0-30, 0-30, 0-60 and 0-100 psi)
3) Temperature measuring instruments (including twelve
copper-constantan thermo-couples, one standard mercury
thermometer and three other mercury thermometers.)
4) One twelve point switch
5) One millivolt Potentiometer
1. Orifice meter
An orifice meter was designed and installed in the liquid line to the packed condenser to measure the Aroclor flow rate. The details of the orificemeter are shown in Figure 6. It consists of a square edged,one eighth inch diameter .circular orifice flanged into a half inch nominal diameter copper tube. The corner taps are connected to a thirty two inch long mercury manometer (Appendix A). d = 0.625 SCALE- FULL SIZE DIMENSIONS IN INCHES MATERIAL- BRASS
Figure 6 Orifice meter 2. Pressure Gauges
Four pressure gauges manufactured by Marsh Instrument
Company were installed to measure the pressures at different points in the apparatus. Their locations are shown in Figure 2.
A 0-100.psi gauge measures the main steam pressure. The 0-60 psi gauge measure the pressure of steam after the pressure re• duction by the pressure regulating valve. The two gauges of
0-30 psi range measure the steam pressure of the packed condenser inlet and the liquid pressure of the packed condenser outlet.
3. Temperature Measuring Instruments
Ten copper - c onstantan thermocouples are installed within the packed condenser and two in the liquid inlet and outlet of the con• denser, as has been already described, to measure the temperature of the Aroclor. Besides the"se thermocouples, three mercury ther• mometers,two of range -20 to 110°C and one of range 25 to 220°F> were also used for the measurement of temperatures. A calibrated mercury thermometer (70 to 101°C) Ch. E.2143 was used to cali• brate a" thermometer and the thermocouples.
4. Twelve Point Switch
This switch was used to select the thermocouples to be read on the potentiometer. 38
5. Millivolt Potentiometer
A Leeds and Northrup millivolt Potentiometer Ch. E. 2266 was used to measure the electromotive force generated by the thermocouples. The thermocouples were calibrated against the calibrated mercury thermometer to give the temperature directly from the potentiometer reading.
The various parts of the apparatus are supported on a panel especially made for this purpose. The panel,with all the important parts mounted in respective positions, is shown in Figure 7. l" l" l" 16' 8 •2 ^ ^2 ^ 8 ^~
S T
GO P C
ID PG ro
12 Point Switch 4 s c
to 3
i" i" ±"
Sch.40 Steel Pipe
O ro
1/4 Base Plate for Pump-
Metal to Metal Joints-Welded 1
—-p——s > s s—^—5"——-p—s s-s—•?—T—>"—ir—y—T—s s s—-p—p—7—v—7—V S S s a. ELEVATION SCALE l" 8;/
Figure 7 Supporting Panel with Main Parts 40
Figure 7 Supporting Panel 41
Figure 7 Supporting Panel 42
CHAPTER FOUR
EXPERIMENTAL PROCEDURE
Before performing the main experiments, it was necessary to perform some preliminary experiments and calibrations. The procedures adapted for all of those,as well as that for main experi• ment and calculations,will be presented in this chapter.
A. DETERMINATION OF SEPARATION TIME FOR WATER FROM AROCLORS
The separation times for water from Aroclor 1242 and from
Aroclor 1248 were measured in two different conditions. First the
Aroclor and liquid water were placed in a test tube and shaken vigorously for some time and then left to separate. The time taken for the water layer to completely separate from Aroclor was measured with a stop watch. This time was found to be less than ten seconds. It was thought that the condensate from steam when condensed in contact with Aroclor might be dispersed in a finer state than was the liquid water. Therefore, the separation time for steam condensate from Aroclor was also measured. A beaker was partly filled with ceramic Raschig rings and Aroclor. Steam was then passed into the Aroclor for some time. The liquid mixture 43
was poured into another beaker and the time was noted for complete separation of the water from the Aroclor. This was found to be fif• teen to twenty seconds. However, the Aroclor layer even after the separation of the water was found to be milky. The density of this milky liquid was measured by weighing two hundred millilitres of it in a measuring flask. This density was found to be exactly the same as that of the pure Aroclor, at that temperature. The density of the milky Aroclor remained unchanged after repeated condensation tests and even after being heated to 100 °C.
B. CALIBRATION OF THERMOCOUPLES
A Colora Ultrathermostat constant temperature bath was used to hold a constant temperature during the tests. Thermocouple number one and a Braun mercury thermometer (-Z0 to 110°C) were calibrated in this constant temperature bath against a standard calibrated mercury o o thermometer. (Ch. Eng. Z143), over a temperature range from 70 to 100 C.
The thermocouple was calibrated by reading the electromotive force gen• erated by the millivolt potentiometer and noting the temperature indicated by the standard thermometer. The Braun thermometer was found to show a temperature -0. 4 degree lower than the true temperature at all temperatures from 70 to 100°C (Appendix B, Table Z). This difference from the true temperature was assumed constant at lower temperatures also and thermocouple number one was calibrated against this thermometer in the range from 30 to 70°C. The calibration curve for the thermocouple (millivolts vs.true temperature, • C. ) is very nearly a straight line (Appendix B, Fig. 28). This
line was extended to get the temperatures up to 105°C This
portion of the line was used only a very few number of times.
The other thermocouples were calibrated against thermo•
couple number one after they had been installed in the condenser.
C. CALIBRATION OF SURGE TANK LEVEL INDICATOR
The surge tank was kept only partly filled at all times during the main experiment and, therefore, provided the necessary capacity
for the steam and the condensate. All the other parts of the apparatus were kept filled at all times. Any increase in the amount of steam
or condensate in the system,caused a level rise in the surge tank
and hence the rate of condensation could be estimated from the rate
of level rise in the surge tank.
To find the volume-liquid level curve, the entire system except the surge tank was filled with liquid. Then water was added to the
surge tank until it reached the zero mark on the level indicator
scale (80 cms. mark). Then accurately measured volumes of water
(200 millilitres each time) were poured into the tank and the liquid level was noted after each addition ( Appendix B, Table 3) . The total volume added was plotted against the indicated level (Appendix
B, Fig. 29). This graph was used to determine the volume of the 45
condensate collected during the time taken for a particular rise in level. The rate of condensation estimated by this method was found to agree with the rate determined by measuring the water collected in the separator-cooler to within +_ 2.0%.
D. CALIBRATION OF ORIFICE:' METER
The orifice meter was calibrated separately for Aroclor 1242 and Aroclor 1248, at six temperatures between 35 and 80 °C. The surge tank was filled with the Aroclor which was heated to the desired temperature by two 250 watt knife heaters. The liquid was kept circulating through the surge tank by the pump by keeping the valve to the delivery line closed.
When the desired temperature was reached in the surge tank, as indicated by a mercury thermometer, the feed valve was opened and the liquid was pumped to a weighing vessel at a particular flow rate as indicated by the manometer reading. An empty five gallon drum placed on the platform of an Avery scale (Ch. Eng. 22 14) was used as the weighing vessel. The scale was set at a weight of about one pound greater than that of the empty drum. A stop watch was activated as soon as the pointer of the scale crossed its middle position. The scale was immediately set to a higher weight and the time was noted when the pointer crossed its middle position again. 46
This was done for from five to nine manometer readings at each
temperature. From the weight difference set on the scale and the
time noted by the stop watch, the flow rate was calculated (Appen•
dix B, Table 4 and 5). This flow rate was plotted against the square-root of the manometer reading to give good straight lines
for different liquid temperatures. The best fit straight lines were
determined by the least square method. From these values of the
flow rates, the flow rates were plotted against the liquid temperature
for definite manometer readings and joined by smooth curves
(Appendix B, Fig. 30 -and 31). These curves were used to find the
flow rates at the specific values of manometer readings, for any
liquid temperature within the range of the calibration.
E„ DETERMINATION OF HEAT LOSSES
The heat losses from the packed condenser were necessary
for the heat balances. These were determined separately for Aroclor
1242 and 1248. For this the Aroclor was circulated through the
closed system at a fixed rate. The electric heater in the separator
cooler was used to heat the liquid. When the liquid temperature
at the bottom of the packed condenser reached the desired value,
the heater was turned off. The large capacity of the separator-
cooler and the surge tank kept the temperature of the liquid constant
long enough for one heat loss test. During this time the liquid
temperatures at the condenser inlet and outlet were measured by means of the thermocouples. From these temperatures plus the flow rate and the specific heat of the liquid at the average temper• ature in the packed condenser, the heat loss was calculated. This was done for a number of liquid temperatures at three different flow rates. {Appendix B, Tables 6 and 7). It was found that the heat loss did not change appreciably with the flow rate. The heat losses were plotted against the average Aroclor temperature in the packed cbndenser (Appendix B, Fig. 32 and 33) and joined by smooth curves. The points for the heat losses for Aroclor 1248 were found to fall on a straight line ('Fig. 33).
F. DETERMINATION OF STEAM QUALITY
The air content of steam was determined several times by measuring the volume of the air and the condensate collected during the experiments.
For measuring the heat content, a weighed thermos flask was half filled with water and weighed again. The temperature of the water was noted with an accurate thermometer (25°F to 220°F) to one tenth of a degree Fahrenheit. The steam sampling valve was open< and left open for a few minutes before testing the quality of steam.
The steam was then bubbled into the water contained in the thermos flask, while the water was kept stirred. All of the steam condensed in the water. The steam was condensed for from thirty 48
to fifty seconds and the final temperature of the water was measured. This temperature remained constant for one minute or more indicating that the heat, losses from the thermos flask were very small. The thermos flask was weighed again. By the difference in the three weights, the weight of the water taken and of the steam condensed were determined. The water equivalent of the thermos flask was previously determined by measuring the temperature rise of a known weight of water when a known weight of hot water was added to it. By a simple heat balance the quality of the steam (dryness fraction) was calculated. Accuracy is of utmost importance in this measurement and therefore special care was taken to prevent splashin.g and an accurate Sartorius (type
2106) balance (Ch.E. 2308) was used for the weighin-gs.
G. MAIN EXPERIMENT
The system was filled with Aroclor through the surge tank using the pump. On opening the Aroclor valve to the condenser, the Aroclor flowed into it from the bottom. It was not found necessary to keep the air vent open at the top of the condenser. The Aroclor forced the air out of the condenser into the separator-cooler,from whence it escaped to the atmosphere through the condensate outlet.
The condensate outlet was shut off when all the air from the separator cooler had escaped to the atmosphere. The system, once filled with f ' . 49
Aroclor, was kept filled until the liquid was drained for changing
the type of the Aroclor.
Each day the experiment was started with the steam quality
measurement and turning on the pump. While using Aroclor 1248, it
was necessary to preheat it before turning on the steam, at the
start of each series of runs, as it is very viscous at room temper•
ature. It was preheated with the electric heater in the separator-
cooler while being circulated through the system. The heater was
turned off when the temperature of the Aroclor in the surge tank
reached about 40°C.
The Aroclor flow rate was next set at the desired value
indicated by the manometer. The steam valve to the condenser was then gradually opened until the desired steam pressure at the con•
denser inlet was shown by the gauge. The condensate left the
condenser with the heated Aroclor and separated from it in the
separator-cooler. The cooling water valve was turned on to cool
the Aroclor before it was recirculated.
The pressure gauge and the manometer readings were checked
intermittently. The thermocouple readings were also taken from time
to timeuntfl. they showed almost a constant temperature distribution
in the condenser. Usually it took from two to three hours for the
steady state to be attained. The time required for a level rise of 50
two to four centimeters in the surge tank was then measured.
During the experiment, if the Aroclor flow rate or the steam
pressure at the inlet to the condenser changed, the temperature
distribution in the condenser was upset. It was, therefore,
necessary to watch for these changes and as soon as any variation
was observed, in the Aroclor flow rate or in the steam pressure, the
respective valves were manipulated to get the original flow rate and
pressure.
It was also observed that if the water was allowed to collect in
the separator-cooler until it came in contact with the cooling coil,
the temperature of the Aroclor in the surge tank dropped considerably,
and this, in turn, upset the temperature distribution in the con•
denser. This is perhaps due to the higher heat transfer coefficient
• for water outside the copper tube compared to that for the Aroclors.
This results in a greater heat exchange with the water flowing
through the coils. Care was taken not to allow the water level to
reach the cooling coils.
The regulation of the cooling water flow rate through the coils
in the separator-cooler was no problem when Aroclor 1248 was
used. The cooling water valve was kept fully open at all the times.
However, with Aroclor 1242 it was necessary to carefully control
the rate of cooling water to get a proper Aroclor temperature at
which all of the steam fed to the condenser would condense in a 51 reasonable height of the packing. At lower temperatures of the liquid, the height was found to be too small to be accurately estimated. On the other hand, if the Aroclor temperature, was too high, a part of the steam remained uncondensed and flowed to the separator-cooler. The rate of cooling water in the Aoroclor
1242 runs was regulated using two needle valves in series.
The rate of condensation of steam was calculated from the level rise in the surge tank. Care was taken to read the level and time as accurately as possible to minimize the possible error.
H. CALCULATION METHODS
The sample calculations for a typical run are presented in
Appendix E. The methods of calculation are given here in brief.
I. Height of Packing Used
The temperature of the liquid in the condenser, as read by the thermocouples (Appendix C, Tables 9 and 11), was plotted against the height of the hot junctions of the thermocouples from the perforated plate supporting the packing (Appendix C, Table 8).
A sample temperature profile is shown in Figure 8. The temperature of the liquid increases with height in the condenser up to a maximum value after which it decreases slowly due to heat losses. The decrease in temperature is almost linear with height. To find the height of packing needed for condensation this straight line was 52
C
o CD o
2.0 h
20 30 40 H , cms
Figure 8 Sample Temperature Profile extended back to the point where the temperature curve separates from this line. This point indicates the height of packing used for condensation and for cooling the condensate to the temperature of the Aroclor,and also indicates the maximum temperature of the
Aroclor in the condenser.
2. Average Liquid Temperature And Temperature Driving Force
The arithmetic mean temperature of the Aroclor in the con- . denser was calculated from the temperature at the liquid inlet and the maximum liquid temperature inside the condenser. However, the arithmetic mean temperature of the liquid in the condenser is not the true mean temperature, since the temperature profile is quite curved. The true mean temperature of the liquid was cal• culated by integrating the temperature with respect to the height and dividing the integral by the total height used. The integration was done by Simpson's Rule using six equal intervals of the packing height.
The temperature of the steam at the bottom of the packing was that corresponding to the pressure at the steam inlet as indicated by the pressure gauge (Appendix C. Tables 10 and 12). A linear pressure drop relationship with height was assumed to calculate, from the total pressure drop in the condenser, the steam pressure
in the condenser at different heights. Due to the curved liquid
temperature profile in the condenser, the log mean value of the : 54
temperature driving force is not applicable. The average temper•
ature driving force was calculated by integrating the temperature
driving force (temperature of the steam minus that of the liquid)
with respect to height using the Simpson's Rule and' dividing the
integral by the height of packing used.
3. Number and Height of Condensation Units
The number of condensation units (N. C. U. ) is defined (Appen•
dix E) as the natural logarithm of the ratio of the temperature
driving force at the bottom of the condenser to that at the height ' ; ••
where condensation is complete. It was calculated using the terminal
temperatures of the steam and Aroclor (Appendix D, Tables 13 and
14). The height of a condensation unit (H. C. U. ) was calculated by
dividing the total height of packing used for condensation by the N. C. U.
4. Heat Balance
The rate of heat transfer was calculated from the Aroclor flow
rate and temperature rise in the condenser. The heat losses from the
active part of the column were added to this value to give the rate
of heat transfer based on the liquid flow rate. The rate of heat
transfer was also calculated from the rate of condensation of the
steam. The two rates of heat transfer were found to agree well with each other (Fig. 23 and 24 and Appendix D. , Tables 15 and 16) except at the highest flow rate of Aroclor 1242. The average of the 55
two rates of heat transfer was used in further calculations. At the highest flow rate of Aroclor 1242, the rate of heat transfer based on the Aroclor flow rate, being closer to the correct value
(Chapter 5) was chosen for further calculations.
5. Volumetric Heat Transfer Coefficient
The average volumetric overall heat transfer coefficient for the condensation of steam was calculated from the rate of heat trans• fer, the mean temperature driving force and the height of packing used for condensation.
6. Reynolds Number
The Reynolds Number for the flow of the liquid through the packing was calculated using the superficial mass velocity of the liquid, the equivalent diameter of the packing and the viscosity of the liquid at its mean temperature. 56
CHAPTER FIVE
RESULTS AND DISCUSSION
A. RESULTS
The results obtained from the experiments on the conden• sation of steam in a packed column in direct contact with Aroclor
124Z and 1248 are presented in Figures 9 to 22 and in Tables 15 and 16 (Appendix D. )
The experiments were performed at four different flow rates of the Aroclors. It was attempted to maintain the flow rates constant in all the runs for a particular flow rate. The effect of slight changes in flow rate between the runs (up to + 2. 5%) was con• sidered negligible. The air content of steam was measured several times and found to be less than 0. 001 percent and so was neglected.
The performance of the condenser is shown in terms of H. C. U. and Ua. The independent variables found to affect these variables
are the superficial mass velocity of the Aroclor and the average
Aroclor temperature. Further, two types of average temperatures were used to represent the results: the arithmetic mean and the true mean temperatures. Although the arithmetic mean temperature is not truly representative of the properties of the Aroclor, it 57 was used since,for design purposes, it is not possible to estimate the true mean temperature without actually doing the experimentsThe arithmetic mean temperature can be easily estimated from the heat duty of the condenser by fixing the inlet liquid temperature or a temperature approach and the flow rate.
1. H. C. U. vs.Arithmetic Mean Temperature
Figures 9 and 10 show the plots of H. C. U. vs. Arithmetic mean temperature with superficial mass velocity of the liquid as para• meter, for Aroclor 1242 and 1248 respectively. These graphs clearly show that there is a definite effect of the liquid temperature as well as of the flow rate on H. C. U. The value of H. C. U. decreases as the arithmetic mean temperature increases and increases with an increase in the flow rate.
2. H. C. U. vs. True Mean Temperature
Similar to the Figures 9 and 10, Figures 11 and 12 were plotted for Aroclor 1242 and 1248 respectively using the true mean temper• atures of the liquid. This has reduced the scatter of the data, specially in the case of Aroclor 1242. These graphs also show the decrease in H. C. U. with the liquid temperature and increase in
H. C. U. with the flow rate. In these graphs, the temperatures are in a higher range than the arithmetic mean temperatures. This is due to the fact that at the bottom of the condenser the Aroclor temperature rises rapidly. 58
L ,lb/hr.ft2
O 1090
0 192 1
A 2365
A 2648
A AA *
A A © A A 0 A A A 0 0 0
fl* • A A 0 O O O o o
50 160 170 180 190 AMT,°F
Figure 9 Results-Aroclor 1242 A A L ,lb/hr. o 1250 • 1875 A 2520 0-9 A 2865
A* 0-8 A A
A 3: °'7h A A
X 0.6 AA A ^ A
0.5 O A 1
0.4f- O
lOQ 30 140 150 160 170 A M T , °F
Figure 10 Results-Aroclor 1248 60
T
0.55
L.lb/hr.ft
0.50 O 10 9 0
• 19 2 1
A 2365 0.45 A 2648
0.40
O 0.35 X o
A 0.30
A AA
# 0%A 0.25 O 9) o
o0
0.20
1 170 180 I 90 200 2 10 220 TMT,°F
Figure 11 Results-Aroclor 1242 61
1 1 1 1 1 1
I.I _A L , lb/hr. ft2 A o 125 0 A
1.0 — CD 187 5
A 2520 A A 2865 0.9
0.8 A
A
3 0.7 — o A X o 0.6 A — 0 A
0 A
0.5 o A 0.4 O 0
a) | f 1 1 1 O | O 150 160 170 180 190 200 TMT,°F
Figure 12 Results-Aroclor 1248 62
3. H. C. U. vs.Superficial Mass Velocity of Aroclor
In Figures 13 to 16 H. C. U. is plotted against the superficial mass velocity of the Aroclor with arithmetic mean and true mean temperatures as the parameters. These graphs do not show the direct results of the experiments but were obtained by cross- plotting from the plots of H. C. U. vs-arithmetic mean temperature and
H. C. U. vs. true mean temperature. These graphs show that the value of H. C. U. increases almost linearly with superficial mass velocity for Aroclor 1248 (Fig. 15 and 16), However, the variation.-, of H. C- U. with superficial mass velocity is not quite linear for
Aroclor 1242. It curves up at high flow rates. The reasons for this difference in the behaviour of Aroclor 1242 and 1248 is possibly the difference in the ranges of Reynolds numbers.
4. H. C. U. vs. Reynolds Number
From the values of superficial mass velocity and the mean temperatures used to plot Figures 13 to 16, the Reynolds numbers were calculated using the equivalent diameter of the packing and the physical properties of the Aroclors at the mean temperature
(Appendix D, Tables 17 and 18). H. C. U. was then plotted against
Reynolds number with arithmetic mean and true mean temperatures as the parameters in Figures 17 to 20 for Aroclor 1242 and 1248.
These graphs show that the experiments were performed in the laminar flow region. H. C. U. increases with the Reynolds number and 63
0.55
0.50h
0.45 h
0.40
0.35 h- O X
0.30h
0.2 5 h
0.20
1000 1500 2000 2500 3000 3500 L, •lb/hr.ft
Figure 13 Results^ Aroclor 1242 64
3 O X
1000 1500 2000 2500 3000 3500 L , lb/hr.ft2
Figure 14 Results-Aroclor 1248 1 I 1 1
0-55
0.50 — —
0.45 — •
0.40 — —
• A 0.35 — —
O
0.30 • A —
• A O T M T,°F 0.25 O A O 1 9 0 o A 2 00 0.20 • 2 1 0
1 \ 1 1 1000 1500 2000 2500 3000 3500 L , lb/hr.ft2
Figure 15 Results-Aroclor 1242 ' 6& 1 1 1 1 1 I"
• O 0.9 —
O •
—
0.7 O • • o — O A X • A A 0.5 — • A — A T M T , °F
— A O 6 0 — A • 70 • A 8 0 0.3 h A 9 0
1 1 l l 1 1 1000 1500 2000 2500 3000 3500 L , Ib/hr.f t2
Figure 16 Results-Aroclor 1248 67
decreases with increase in the mean temperature as would be expected. The variation of H. C. U. with Reynolds number for the constant values of the mean temperature is very close to linear for Aroclor 1248,in which case the Reynolds numbers are less than
2. 0 when arithmetic mean temperatures were used and are less than 4. 0 when true mean temperatures were used. For Aroclor
1242, the variation of H. C. U. with Reynolds number is not quite linear because in this case the Reynolds numbers were in a higher range. A similar behaviour may be expected with Aroclor 1248 at higher
Reynolds numbers.
5. Ua vs. True Mean Temperature
Figures 21 and 22 show the effect of the true mean temperature and the liquid flow rate on the average volumetric overall heat trans• fer coefficient for Aroclor 1242 and 1248 respectively. It appears from these graphs that Ua increases rapidly with increase in the true mean temperature, but the effect of the flow rate is not definite.
The values of Ua are quite low at the lowest flow rate studied. At higher flow rates, the effect of the flow rate appears to diminish.
The points corresponding to the three highest flow rates cluster around the same region.
B. REPRODUCIBILITY OF THE RESULTS
The mean temperature of the Aroclor is not a variable which 0.45r-
0.35 h
3 O X
0.25 H
0.15 h
Figure 17 Results-Aroclor 1242 o
0.8 o e
e
o 0.6
3 O X e
o
0.4 A M T ,°F
O 145
8 15 0
• 15 5
0.2
0 0.5 l.O 1.5 2,0 2 Re
Figure 18 Results-Aroclor 1248 70
z> u X
0.2h
Figure 19 Results-Aroclor 1242 71
LI
0.9 o
o
0.7 O e o X o e ©
0.5 © © T M T ,°F
© o I 6 0
© I 7 0
© 180
0.3h 190
Re
Figure 20 Results-Aroclor 1248 72
1500
70 180 190 200 210 220 TMT ,°F
Figure 21 Results-Aroclor 1242 73
e
•©_ 2100 © e ©
oLL.
IO* 1700 o o ©
CD o e Z> e 1300 o
0 L , lb/hr.ft: ©
O 1250 © e 1875 900 O e © 2520 © 2865 e i i 150 160 170 180 190 2 00 T MT , °F Figure 22 ,. Results-Aroclor 1248 74
could be fixed as desired. The true mean temperature is obtained from the Aroclor temperature profile in the condenser. Still,as an indication of the reproducibility of the results, there were eight cases (Fig. 11 and 12 and Appendix D, Tables 15 and 16), where almost identical true mean temperatures of Aroclor were obtained from two independent runs. The corresponding values of H. C. U. were found to differ from 0. 39 to 1. 35 percent.
However, the exact calculation of the reproducibility of the
Aroclor flow rate and the mean temperature is not possible. The flow rate varies within + 2. 5% of its mean value due to the changes in Aroclor temperature which alter the manometer reading for the same flow rate. The reproducibility of the mean temperature is governed by the quality of the steam and by the cooling water flow rate. In order to exactly reproduce a particular run, it is necessary to have the same Aroclor flow rate. Then if the flow rate of the steam is fixed, there is one and only one inlet temper• ature of the liquid which would give the same value of the true mean temperature otof the arithmetic mean temperature. In practice, it was found very difficult to get the desired liquid inlet temperature by regulating the rate of cooling water. Even if the same steam flow rate were used the difference in its heat content, presented the same problem. . However itwasnot difficult to find a setting which would give a mean temperature in a given range.
C ACCURACY OF THE RESULTS
The accuracy of the results is limited by the accuracy of the
estimation of the height of packing used for condensation. The
graphical method for estimating the height of the packing used can
give values differing from the correct values by as much as + 1.5
centimeters. This difference limits the accuracy of the valuesof H. C. U.
and Ua to + 10% in most of the cases. Any inaccuracy in the height
of the packing does not affect the value of the mean temperature
appreciably.
The joint accuracy of the orificemeter calibration, of the steam
quality measurement, of the rate of condensation and of the Aroclor
temperature measurement has been quite good as is evident from
the heat balances (Fig. 23 and 24 and Appendix D, Tables 15 and 16).
The points lie on both sides of the diagonal in these graphs and are within
_+ 10% from it except at the highest flow rate of Aroclor 1242.
At the highest flow rate of Aroclor 1242 studied, the rate of heat
transfer based on the condensation of the steam is always considerably
lower than that based on the Aroclor 1242 flow rate and temperature
rise. The reason for this one sided difference was shown by subse•
quent experiments to be the fact that at high flow rates of Aroclor
1242, the condensate did not separate completely in the separator-
cooler,but passed on to the surge tank and accumulated there. The 76
Qy= 0L ± 10% 8000
6000
CD
>
4000
2000
2000 3000 4000 5000 6000
QL,BTU/hr
Figure 23 Heat Balance-Aroclor 1242 Figure 24 Heat Balance-Aroclor 1248 78 water accumulation in the surge tank caused a lower reading of the level indicator than the actual level in the tank. Thus the calculated
rate of condensation was lower than the actual rate of condensation,
and for this reason the rate of heat transfer based on the rate of
condensation was lower at the highest flow rate of Aroclor 124Z.
In these runs,since the rates of heat transfer based on the Aroclor flow rates and temperature rise were closer to the actual rates, they were used to calculate Ua. With Aroclor 1248 the larger density difference from water prevented the carry over of the condensate
at high flow rates.
D. COMPARISON WITH LITERATURE VALUES
In the literature, no work has been reported on the conden• sation of steam in a packed column in direct contact with an immis• cible liquid in co-current flow. Therefore, it was necessary to compare these experimental results with some published work on condensation in counter-current flow. Wilke et al. (9) have reported experimental work' using Aroclor 1248 to condense steam in a packed column. It was therefore decided to compare the experimental results of the present work with the equation proposed by Wilke et. al. (9)
Lackey (7) has also proposed a similar equation; therefore the results were compared with his equation also.
The thermal conductivity data for Aroclor 1242 is not given in 79
reference 19, therefore, the values of H. C. U. could not be calculated for this case using the equations suggested by Wilke
(9) or Lackey (7). The values of H. C. U. were calculated for
Aroclor 1248 at the experimental flow rates using these equations.
The physical properties were estimated at the true mean Aroclor temperatures (Appendix E). These calculated values of H. C. U. were plotted on a log-log scale against the absolute values of true mean temperature with the flow rate as parameter, together with the experimental results (Fig. 2 5).
Although Wilke et. al. (9) have not indicated any definite effect of Aroclor temperature on H. C. U, this graph clearly shows that a definite effect of the temperature on H. C. U. is theoretically expected. The H. C. U. decreases with increase in mean liquid tem• perature and increases with flow rate, as has been shown by the results of this study.
While calculating the values of H. C. U. from Lackey's equation (7)
0.155 N0. 5 0.333 0. 556-0. 152 log L HCU = HTU L(W)(T^) {rrj (^P) (^f)
and Wilke's equation (9) Q> „ 0. 5. . ,0. 329 ^ x0. 554-0. 157 log L
Hcu = HTUL (150 to 200 °F), the only term which changes appreciably is the viscosity ratio term. As the temperature increases from 150 °F 80 to 200 °F. decreases from 13.44 to 5. 14 Dw irregularly changes from 0. 0359 to 0. 0357 c< 'w increases from 0. 707 to 0. 722 ^w remains practically constant at 1.74 Further, HTU, , . is a function of only the flow rate for a fixed L(w) size of the packing. Thus if the other terms are assumed constant in this range of temperature, the equations simplify to the form H n CU=f«L,(jy (i) where n = 0. 155 for Lackey's equation and n = 0. 55 for Wilke's equation. IX , the viscosity of water at 25 °C is constant. r w f°r rnost liquids is related to the absolute temperature by (2 5) b /U1 = a(T) (2) where a and b are constants. On substitution in Equation (1) and including the constants in f (L), HCU = f (L) (T)m (3) where m = b.n. (4) Equation (3) represents parallel straight lines on log log plot for constant values of L. It was, therefore, decided to plot H. C. U. and absolute true mean temperature on log-log graph for the comparison of experi• mental results with the equations of Lackey (7) and Wilke (9) (Fig. 25). Figure 25 Comparison of Results- Aroclor 1248 1.0 L , lb/hr.ft2 o 1 090 3 19 2 1 0.6 0 2365 © 2648 0.4 O X 0.2 0.1 1 640 6 60 680 700 T,°R 00 Figure 26 Results-Aroclor 1242 83 It can be noticed in Figure 2 5 that the curves obtained from Lackey's equation (7) and Wilke's equation (9) for different values of L are very nearly straight lines, parallel to each other. This supports the hypothesis propounded above. The experimental results for Aroclor 1248 (Fig. 25) and 1242 (Fig. 26) also lie very well on parallel straight lines except for five points, which may indicate a limit to this relationship. The distances between the lines for different flow rates are (Fig. 25) the same in all the three sets of lines. This shows that the dependence of H. C. U. on the flow rate L is the same in the three cases. The lines obtained from Lackey's equation are far below the experimental results and have a very small negative slope. However, Wilke's equation gives results of the same order of magnitude as do the experiments but it gives a negative slope smaller than the lines for the experimental results. This agreement is rather for• tuitous because Wilke studied (9) counter-current turbulent flow. This agreement is most likely due to the use of the incorrect estimate of mean liquid temperature in the condenser by Wilke (9). However, there is always the possibility that the proposed equation may also hold for. cccurrent laminar flow. The common slope of the !-. '. straight lines through the experi• mental points for Aroclor 1248 is m = -13.90 84 The value of b in Equation (2) page 80 for Aroclor 1248 is b = ^12.00 n = m = 13. 9 = 1. 16 b -12.0 The common slope of the . straight lines through the experi• mental points for Aroclor 1242 is m = -8. 75 The value of b for Aroclor 1242 is b =-7. 94 n = m =-8.73 =1.10 b -7.94 The values of the viscosity exponent 'n' are almost equal for Aroclors 1242 and 1248. This is to be expected but since the value is different from those proposed by Wilke or Lackey a new equation must be found to describe these results. E. BEST EQUATIONS FITTING THE EXPERIMENTAL RESULTS Because of the close agreement between the viscosity exponents n, for Aroclor 1242, and 1248, it was decided to find the equations of the form HCU = F ( )n to fit the experimental results.F will change with the flow rate. This equation is essentially the same as Equation (1) on page 80 . The change in F was found to be linear with L for Aroclor 1248 (Fig. 27) . from the plot of /A ve T on log log ecale. 85 86 The best equation to fit the experimental results for Aroclor 1Z48 was found to be (Appendix E) HCU = (0. 027 65 + 1. 244 x 10_5L) (/X)1' 16 2 where L is superficial mass velocity of Aroclor 1248, lb/hr. ft. and /A- is viscosity of Aroclor in centipoise at its mean temperature. The variation of F with L is not quite linear for Aroclor 1242 (Fig. 27). A quadratic equation was fitted to these values of F, but this equation showed a minimum value of F at L = 1380. This is not a reasonable interpretation of the data. A similarity between the F - L relationship for Aroclor 1242 and 1248 is also anticipated. However, the data are not sufficient to predict two similar equations for the two cases. It was, therefore, decided to relate the values of F for Aroclor 1242 with L bytwo straight lines (Fig. 27). F = 0. 0535 + 8. 90 x 10"6L when L 2290 F = -0..-.073J7+ 6. 44 x 10~5L when L > 2290 HCU is given by HCU = F ( j*)1- 10 2 where L is superficial mass velocity of Aroclor 1242, lb/hr. ft. and ^A. is its viscosity at true mean temperature, cp.. F. COMPARISON OF THE RESULTS FOR AROCLOR 1242 AND 1248 A comparison of the maximum liquid temperatures in the condenser t for Aroclor 1242 (Table 13) and Aroclor 1248 (Table 14) 87 reveals that a much closer temperature approach could be obtained with Aroclor 1242 than with Aroclor 1248. The values of HCU for a particular flow rate and a particular mean temperature are considerably lower for Aroclor 1242. Thus Aroclor 1242 is more suitable and efficient for direct contact condensation than Aroclor 1248. However, the difference in density from that of water is not as great in the case of Aroclor 1242 as in the case of Aroclor 1248. This slows the separation of Aroclor 1242 from water but it will also increase the operating range for counter-current condensation. The equations given in the previous section for Aroclor 1248 and 1242 are the ones which describe the results from this study. The exponent 'n' of the viscosity is almost the same for the two systems. The values of F include the density, thermal diffusivity and surface tension of the Aroclors besides the flow rate. In the range of flow rate studied, F was found to be very nearly linear with L for Aroclor 1248 (Fig. 27). For Aroclor 1242, F appears to be fairly linear with L in the lower flow range (Fig. 27), but curves up at the high flow rate. This type of behaviour may be expected from Aroclor 1248 also at still higher flow rates since the value of Reynolds number at which this upward curve occurred was not reached with the more viscous Aroclor 1248. Therefore, in the absence of more extensive data, the F - L relationship for Aroclor 1242 was approximated by two straight lines. 88 CHAPTER SIX CONCLUSIONS AND RECOMMENDATIONS The main objective of this work was to design, to build and to check the performance of a packed condenser for condensing steam in direct contact with immiscible commercial heat transfer agents. During the experimental runs, it was observed that the apparatus worked quite satisfactorily without the crackling noise normally associated with the direct contact condensation. Once the Aroclor flow rate, cooling water flow rate and the steam pressure were set, the equipment operated almost automatically. The aluminum shields attached to the hot junctions of the thermocouple prevented the con• tact of rising steam bubbles with the thermocouple hot junctions as is evident from the agreement between the heat balances and from the fact that the thermocouple readings were steady. The accuracy of the results obtained has been discussed in the previous chapter. It is suggested that in order to improve the accuracy of the results, some more accurate method for determining the height of the packing used for condensation be found. 89 The experimental results of this work were compared (Fig. 25) with the equations proposed by Lackey (7) and by Wilke et. al. (9). The experimental results are of the same order of magnitude as those calculated using Wilke1 s equation (9). The effect of the liquid temperature, which in fact is mainly due to a large change in viscosity, was predicted theoretically by the equations given by Lackey (7) and Wilke (9), but it has not been reported earlier in any of the experi• mental works published in this field. Two empirical equations have been developed to describe the results of this study. They relate HCU with the flow rate and Aroclor viscosity at its mean temperature. The viscosity exponents are almost equal for both the systems studied. The variation of the factor F with flow rate is not quite similar for the two. systems in the flow ranges studied. It is very strongly recommended that an extensive investi• gation be undertaken using different sizes of packings, different size of the condenser and a wider range of flow rates to check for the variation of F with flow rates and to extend the data available for condenser design. It is expected that if enough data were obtained on different systems, some direct correlation could be obtained for the estimation of HCU or Ua for a packed condenser from the physical properties of the liquid, the packing material and the operating conditions. This correlation could be used to design the commercial 90 direct contact packed condensers, using immiscible heat transfer agents. The basic steps in the design procedure would be 1) to select a particular liquid flow rate , 2) to calculate the diameter of the packed column from the usual flooding, characteristics, 3) to assume a temperature approach (20°F is quite safe); 4) to calculate the inlet temperature of the liquid from a simple heat balance with the heat duty of the condenser, and thence the mean liquid temperature, 5) to estimate the HCU from the correlation for the selected flow rate and mean temperature, 6) to calculate the NCU from the equation NCU =ln / ^1 r *! 1 t „ - t„ s2 2 7) to calculate the height of the packing from the equation Height = HCU x NCU , 8) to calculate the total cost . This would have to be done for several different flow rates to find the optimum design and the optimum operating conditions. NOMENCLATURE A Area, ft. A. M. T. Arithmetic Mean Temperature, °F C Coefficient of Discharge, Dimensionless Cp Specific Heat, BTU/lb., °F. or Cal/gm., °C D Diffusivity, cm /sec. d Diameter, ft. 2 g Acceleration due to gravity, ft/sec F A factor as defined in Chapter 5. H Height of the packing used for condensation, cms H LOS Heat loss from the condenser, BTU/hour. HCU Height of Condensation Unit, ft. HTU Height of Transfer Unit, ft. ha Volumetric Heat Transfer Coefficient for Liquid filr BTU/hr. , ft. °F. h Manometer Reading, cms of mercury k Thermal conductivity, BTU/hr., ft. °F/ft. k a Mass Transfer Coefficient, hr ^. JLJ 2 Superficial Mass Velocity of Liquid, lb/hr. ft. L Number of Condensation Units, Dimensionless NCU Number of Transfer Units, Dimensionless NTU 2 P Pressure, lb/in Q Rate of Heat Transfer, BTU/hr. Re Reynolds Number, Dimensionless 2 s2 T Area of the Orifice, ft. T. M. T. Absolute True Mean Temperature, °R. True Mean Temperature, °F 92 t Temperature, C Ua Average Volumetric Overall Heat Transfer Coefficient, BTU/hr. , ft.- °F. V Volume of condensate collected, ml 3 v Volume of the packed column, ft w Liquid Flow Rate, lb/sec x Dryness Fraction of Steam, Dimensionless Z Liquid Level in Surge Tank, cms Greek Letters: 2 Thermal Diffusivity, cm /sec P Orifice Diameter Ratio, Dimensionless Increments, Dimensionless £ Porosity, Dimensionless Surface Tension, dynes/cm p 3 Density, gms/rnl or lb/ft e Viscosity, centipoise or lb/ft, hr. Time, sees Subscripts: 1, 2, etc. Different Locations e Equivalent i Inlet 1, L Liquid 0 Outlet s Steam tank Surge tank V Vapour w Water at 2 5°C No subscript Aroclor 93 BIBLIOGRAPHY Ruckenstein, E. , Metiu, H. , Chem. Eng. Sc. 20, 173 (1965) Tanner, D. Wl; Potter, C. J. , et alvInt. J. Heat and Mass Trans• fer 8, 419 (1965) Coons, K. W. , Direct Condensers, Bull.No. 3, Eng. Exp. Station, College of Eng. , Univ. of Alabama, June 1953 Has son, D. ,Luss, D. and Navon, U. , Int. J. Heat and Mass Trans• fer ]_, 983 (1964) Hasson, D. ,Liiss, D.and Peck, R. , Int. J. Heat and Mass Trans• fer^ 969 (1964) Olander, D. R. , Ind. Eng. Chem. 5_3_(2), 121(1961) Lackey, D. L. , U. S. Atomic Energy Comm. UCRL 1033,9 (1962) Hu, Shao Chio, The Refining Engineer, C-12, 722 (1956) Wilke, C.R., Cheng, C. T. , Ledesma, V. L. and Porter, J.W. Chem. Eng. Progress _59 (12), 69 (1963) Cheng, C. T. , "Direct Contact Condensation in a Packed Tower" M. S. Thesis, Univ. of Calif. , Berkley (1963) Harriott, P. and Wiegandt, H. , A.I. Ch . E. Journal 10_ (5), 755 ( 1964) Ciborowski, J. and Surgiewicz, J. , Brit. Chem. Eng. 7_, 763 (1962) ~~ Levine, D. G. , and Friedlander, S. K. , Chem.Eng. Sc. 13, (2), 49(1960) Pinder, K. L. , Research Proposal to the U. S. Office of SalineWater (April, 1964) Sherwood, T. K. , Shipley, G.H., and Hollo way, F. A. L. , Ind. Eng. Chem. 30, 765 (1938) 94 Sherwood, T. K. and Holloway, F. A. L.,Trans.A. I. Ch. E. 36, 39 (1940) Wilke, CR., Chem. Eng. Progress, 45, 218 (1949) Harriott, P. ,and Wiegandt, H., Personal Communication to Dr. K. L. Pinder (Oct. 1963) "The Aroclor Compounds, " Monsanto Chemical Company, Organic Div. St. Luis, Missouri. "Tower Packings, " Bull. TP54R, U. S. Stoneware, Akron 9, Ohio Chiarulli, P. and Dressier, R. E., J. of Applied Physics, 28, 990 (1957) Brass, G. H.> Chemical Engineering, 60^ 223 (April, 1953) Vener, R. E., Chemical Engineering, 63, 175 (August, 1956) Shulman, H.L. et. al., A. I. Ch. E. J. 1_, 247 (1955) . Perry, J.H. Chemical Engineers' Hand Book, 3rd Ed. McGraw-Hill Book Co. Inc. p. 372 Ibid., p. 403 Ibid., p. 405 95 APPENDIX A BASIC DESIGN CALCULATIONS The entire apparatus was designed on the basis of using an eighteen inch long section of four inch internal diameter, pyrex glass pipe as the packed condenser.. 2 1 ft3 Total volume of the column = 4 ) x 1 8 x —3 4... . 1 = 0. 131 ft3 A. PACKING REQUIREMENT The best size of the packing to reduce channeling and pressure drop = x Internal dia. of the column 10 1 = _1_ x 4 = 0.4 inch 10 , 3 inch 8 For 3/8" Ceramic Raschig rings (20) , 3 weight of rings per ft of column space = 52 lb • weight of rings required = 0. 131 x 52 = 6.81 lb B. AROCLOR FLOW RATE Assuming no packing, the volume of liquid required to fill the 3 column = 0. 131 ft If this liquid be replaced every minute, flow rate =0.131 CFM = 0. 131 x 7. 48 = 0. 981 GPM ~ 1 GPM This flow was presumed to be the maximum. C. STEAM RATE o A temperature rise of 50 C was presumed in the Aroclor, at the maximum flow rate of 1.0 GPM. For Aroclor 1248 (19) Density = 12. 04 lb/gal Mean Sp. heat (50-100°C) = 0. 290 BTU/lb. °F . . Heat extracted in the column = 12. 04 x 1. 0 x 0. 29 x 50. x 1. 8 B.TU = 315 BTIimin min For Aroclor' 1242 (19) Density = 11. 50 lb/gal Mean Sp. heat (50-100°C) = 0. 310 BTU/lb. °F Heat extracted in the column = 11.50 x 1.0x0.31x 50 x 1.8 BTU = 321 BTU/min min Neglecting the sensible heat, the heat given up by one lb of steam during condensation (say at 2 5 psia) = 952. 1 BTU . . Maximum rate of condensation of steam =321 952. 1 = 0. 337 lb/min In order to design a separator it was necessary to find the separation characteristics of water from the Aroclors. Simple experiments were 97 done for measuring the separation time. It was found that when Aroclor 1248 or 1242 is shaken vigourously with liquid water, the liquids separate almost instantaneously. The separation time being less than ten seconds. However, when steam was bubbled into a beaker con• taining some Raschig rings and Aroclor 1248 or 1242, it was found that the water separates from Aroclor rapidly (t ime being ten to twenty seconds) but the Aroclor layer became milky. The milky liquid was found to have exactly the same density as pure Aroclor. It does not break on.keeping for a long time or on heating. It was, therefore, decided to use this liquid as such, after water.was removed from it. On the basis of the above experiments a separation time of one minute was allowed. 3 Volume of Aroclor = 0. 131 ft 3 Volume of water = 0. 00 562 ft 3 Total volume of liquids = 0. 13662 ft Allowing 50% of this volume for the accumulation of water, total 3 volume required = 1.5 x 0. 13662 = 0. 205 ft In the beginning it was decided to have a rectangular plastic tank for separation. A cross section of 6" x 5" gives a liquid velocity = = 0. 13662 x 144 = 0. 655 ft/min 98 The length of tank required to provide a volume of 0. 20 5 ft = 0. 205 x 144 - 0. 985 » 1 ft 6x5 This length allows more than 1. 5 min. for the liquid to flow through the tank, enough for separation. Initially, a plastic tank (Perspex) 6' x 5"x 1 ft with pyramid shaped roof was made, which worked well as far as .'separation was concerned, but the plastic was found to be attacked by Aroclor at high temperatures. Therefore, it was decided to design and build a glass column for this purpose. If a column of one foot length were used, the cross-sectional 2 2 area required = 0.205 ft = 29. 5 in . A six inch internal diameter 1 2 glass column having a cross sectional area of 28. 43 in and one foot long was chosen. It was also decided to install a cooling coil in the column. E. SURGE TANK This tank was designed to hold the liquid for "recirculation and to allow for the increase in volume due to condensation. A rectangular size of 6" x 6" x one foot length was arbitrarily decided. The tank was to be open to the atmosphere. At first a plastic tank was made but later was replaced by a galvanized iron tank. 99 F. LIQUID PUMP , A pumping capacity of one gallon per minute was needed to give the maximum flow rate of Aroclor. Further, it was decided to use the steam up to a pressure of 20 psig for condensation. Accordingly, the pump must be able to circulate the liquid at one gallon per minute against a pressure of at least 20 psig. From an Eastern Industries pamphlet, a gear pump model GW-1, 1 /4 horsepower was found to be quite satisfactory. G. FLOW METER It was necessary to accurately measure the flow rate of Aroclor to the condenser. For this an Orifice: meter was designed. Primarily it was designed for Aroclor 1248 but later it was found to work satis• factorily with Aroclor 1242 as well. The maximum flow rate of Aroclor 1248 = 1 GPM = 12. 04 lb /min. A half inch nominal diameter hard copper pipe was chosen to instal the orifice due to its strength to support the flanges. Assuming an orifice diameter of 1 /8 inch and average temperature of 50°C at the orifice, the properties of Aroclor 1248 are (19) 3 Density p = 1.43 gm/cc =89.1 lb Ut Viscosity ^X. =90 Saybolt Universal seconds = 0. 17 Stokes (Kinematic Viscosity) = 0. 17 x 1. 43 Poise 100 = 0. 17 x 1. 43 x 100 x 2. 42 lb hr, ft. = 59.3 lb hr, ft. . . Reynolds number at the orifice Re = do W =(1/8)x 12. 04 x 60 x 144 Ao^ ' 12 x JA_ / 1\2 x 59. 3 4 [BI = 1490 Diameter ratio A ^ 1 /8 = 0.25 ' " " 1 12 The coefficient of discharge for a circular, square edged orifice is (27) C =0.65 The mass rate of flow is given by (26) TA h w = CYS, '2 J~i~r& Y = 1 for liquids 2 L '•Ah =/_w_\ / 1 - /3M ^C s2/ (T7^ = 2 5. 5 ft of Arochor = 2 5.5 x 30.48 = 63. 8 cms of mercury 13. 6 - 1. 43 This much pressure drop can be easily read by a 80 cms long manometer. It was decided to make a 30 cms long manometer and to fill it up to about 40 cms with mercury. It can thus read pressure drops up to 70 cms. The pressure drop for lower flow rates will also be enough to be measured accurately. 101 APPENDIX B CALIBRATIONS The calibration curves which were used in the calculation of the results are presented in this section. A. THERMOCOUPLE AND THERMOMETER CALIBRATION The standard thermometer, used to calibrate thermocouple number one and a 'Braun' mercury thermometer, was a Taylor Mercury- in-glass, total imersion thermometer of range from 70 to 101°C and graduations of 0. 1°C (Serial No. 7A762980). This thermometer had been compared by the National Research Laboratories, Division of Physics, with the Standards of the N. R. L. on April 9, 1959, and found to indicate a temperature greater than the true temperature by 0. 1 °C (nearest first decimal place). The results of the calibration are given in Table 2 and in Figure 28. 102 TABLE 2 Calibration Data for Thermometer and Thermocouple No. 1 ' ' , • Standard 'Braun' Thermocouple True Thermometer Thermometer- No. 1 Temperature o o °C C rr.V C 70. 3 • 69. •8 2. 910 70,. 2 74. 5 74. 0 3. 090 . 74.. 4 81. 0 80. 5 3. 380 80.. 9 85. 0 84. 5 3. 550 84,. 9 91. 0 90. 5 3. 820 90,. 9 95. 7 95. 4. 040 95,. 6 99. 9 99. 5' 4. 243 99., 8 3L. 5 1. 230 31, , 9 40. 5 1. 615 40., 9 50. 5 2. 045 50. 9 55. 5 2. 265 55.. 9 60. 0 2. 470 60. 4 65. 5 2. 710 65. 9 NB . A constant difference of 0. 4 C was observed between the readings of the Braun thermometer and the true temperature in the range 70-100 C. The same difference was assumed in the lower temperature range to estimate the true temperature. 103 1-0 2-0 3-0 4.0 Thermo couple Reading,mV Figure 28 Calibration Curve for Thermocouple No. 1 B - CALIBRATION OF SURGE TANK LEVEL INDICATOR TABLE 3 Calibration Data for Surge Tank Level Indicator Volume added, ml Level on,the scale, cms' 0 80. 00 200 80. 45 400 80. 90 600 81. 35 800 81. 80 1000 82. 20 1200 82. 60 1400 83.00 1600 1 • 83.60 1800 " 84.05 2000 84. 50 2200 84.95 2400 85. 35 2600 85. 90 2800 86. 35 3000 86. 80 3200 87. 20 3400 87. 75 3600 88. 20 3800 88. 60 105 0 2 4 6 8 Z , cms Figure 29 Volume-Level Curve for Surge Tank 106 C - CALIBRATION OF ORIFICE". METER TABLE 4 Orifice meter Calibration for Aroclor 1242 Temperature Manometer Liquid rol- Time Flow rate in surge tank reading lected 6? sees Aw/8 C Ah, cms £\»/lbs lb /sec 30. 0 1. 5 1. 0 39- 0 0. 02564 1. 224 30. 0 4. 0 1. 5 32. 5 0. 0461 5 2. 000 30. 0 6. 0 2. 0 35. 5 0. 0 5633 2. 450 30. 0 7. 5 2. 0 31. 0 0. 06451 2. 738 30. 0 10. 0 2. 0 27. 0 0. 07407 3. 162 40. 0 1. 5 1. 0 37. 0 0.02702 1. 224 40. 0 4. 0 2. 0 43. 0 0.04651 2. 000 40. 0 6. 0 2. 0 35. 0 0.05714 2. 450 40. 0 7. 5 2. 0 30. 5 0.06557 2. 733 40. 0 10. 0 2. 0 26. 0 0.07692 3. 162 50. 0 1. 5 1. 0 35. 0 0. 02857 1. 224 50. 0 4., 0 1. 5 31. 5 0. 04761 2. 000 50. 0 6.. 0 2. 0 34. 5 0. 05797 2. 450 50. 0 7.. 5 2. 0 30. 5 0. 06557 2. 738 50. 0 10. 0 2. 0 26. 5 0. 07547 3. 162 107 (Table 4 continued) 60. 0 1. 5 1. 0 37. 0 0. 02702 1. 224 60. 0 4. 0 1. 5 32. 5 0. 04615 2. 000 60. 0 6. 0 2. 0 35. 0 0. 05714 2. 450 60. 0 7. 5 2. 0 31. 0 0. 06451 2. 738 60. 0 10. 0 2. 0 28. 0 0. 07142 2. 162 70. 0 1. 5 1. 0 37. 5 0. 02667 1. 224 70. 0 4. 0 1. 5 32. 5 0. 0461 5 2. 000 70. 0 6. 0 2. 0 35. 5 0. 05634 2. 450 70. 0 7. 5 2. 0 31. 5 0. 06349 2. 738 70. 0 10. 0 2. 0 28. 5 0. 07018 3. 162 80. 0 1. 5 1. 0 38. 0 0. 02632 1. 224 80. 0 4. 0 1. 5 33. 0 0. 04545 2. 000 80. 0 6. 0 2. 0 36. 0 0. 05556 2. 450 80. 0 7. 5 2. 0 32. 0 0. 06250 2. 738 80. 0 "10. 0 2. 0 29. 0 0. 06897 3. 162 A h, cms o 1.5 CD 4.0 6.0 • 7.5 Figure 30 Orifice, meter Calibration Curvee-Aroclor 1242 109 TABLE 5. Orifice, meter Calibration for Aroclor 1248 Temperature in Manometer Liquid Time Flow Rate Surge tank C reading Collected 0, sees Aw/0, lb /sec _,h, cms Aw, lbs L_ 34. 0 2. 0 1. 0 40. 0 0.02500 ' 1. 414 34. 0 4. 0 2. 0 51. 0 0.03922 0. 000 34. 0 6. 0 2. 0 40. 0 0.05000 2. 450 34. 0 8. 0 2. 0 34. 0 0.05882 2. 828 34. 0 10. 0. 3. 0 47. 0 0.06383 3. 162 34. 0 12. 0 3. 0 40. 0 0.07500 3. 462 34. 0 14. 0 3. 0 37. 0 0.08108 3. 740 34. o' 16.0 3. 0 34. 0 0.08824 4. 000 50. 0 2. 0 2. 0 66. 0 0. 03030 1. 414 50. 0 4. 0 2. 0 46. 0 0. 04348 2. 000 50. 0 6. 0 2. 0 36. 5 0. 05479 2. 450 50. 0 8. 0 2. 0 31. 5 0. 06350 2. 828 50. 0 10. 0 3. 0 42. 0 0. 07143 3. 162 50. 0 12. 0 3. 0 39. 0 0. 07700 3. 462 50. 0 14. 0 3. 0 35. 0 0. 08571 3. 740 65. 0 2. 0 2. 0 64. 0 0. 03125 1. 414 65. 0 4. 0 2. 0 44. 0 0.04545 2. 000 65. 0 6. 0 2. 0 35. 0 0.05714 2. 450 65. 0 3. 0 2. 0 30. 5 0.06557 , 2. 828 65. 0 10. 0 2. 0 27. 5 0. 07273 3. 162 65. 0 12. 0 3. 0 37. 5 0.08000 3. 462 80. 0 2. 0 2. 0 64. 5 0.03101 1. 414 80. 0 4. 0 2. 0 43. 0 0.04651 2. 000 80. 0 ' 6. 0 2. 0 35. 0 0.05714 2. 450 80. 0 8. 0 3. 0 , 47. 0 0.06383 2. 828 80. 0 10. 0 3. 0 42. 5 0.07059 3. 162 80. 0 12. 0 3. 0 39. 0 0.07692 3. 462 95. 0 2. 0 1.0 31.0 0. 03226 1. 414 95. 0 4. 0 1. 0 22. 0 0. 04545 2. 000 95. 0 6. 0 2. 0 36. 0 0.05556 2.450 95. 0 8. 0 2. 0 32. 0 0.06250 2. 828 •95. 0 10. 0 3. 0 45. 0 0.06667 3.162 95. 0 12. 0 2. 0 27. 0 0.07407 3.462 110 O.IO 0.08 o .CO 0.06h 0.04 0.02r- 4 0 6 0 80 oo tank 1 u Figure 31 Orifice meter Calibration Curves-Aroclor 1248 Ill D. DETERMINATION OF HEAT LOSSES TABLE 6 Determination of Heat Losses for Aroclor 1242 Ah, T <> „ Th. Co. w T T T Heat loss cms it-ank i*., Th. Co. 2 av ,. °C No 1 No. 12 lb/sec o o^ o_ BTU/hr mv mv 6. 0 57. 0 2 . 080 2. 060 0. 0573 52. 0 51. 4 51. 70 66. 8 10. 0 55. 0 2 . 005 2.. 000 0. 0752 50. 3 50. 0 50. 15 43. 8 , 4.0 55. 0 2 .015 1,. 985 0. 0470 50. 5 49. 6 50. 05 82. 2 6. 0 67. 0 2 . 440 2.. 380 0. 0564 59. 9 58. 6 59. 25 145. 0 4. 0 75. 0 2 . 740 2.. 630 0. 0454 66., 6 64. 2 65. 40 219. 0 10. 0 76. 0 2 . 775 2. 685 0. 0708 67. 5 65,. 6 66. 55 268. 0 6. 0 80. 0 3 . 005 2.. 865 0. 0555 72.. 6 69 .5 71. 05 346. 0 6. 0 90. 0 3 . 420 3.. 220 0. 0553 81 . 8 77. 4 79. 60 496. 0 TABLE 7 Determination of Heat Losses for Aroclor 1248 A hi,, T Th. Co Th. Co. w T Heat loss cms No. 12 lb / s e c Tl T2 am T tank No 1 BTU/hr mv mv ° C ° c °c 6. 0 68. 0 2. 260 2. 250 0. 05625 56.0 55. 5 55. 75 51.9 6. 0 75. 0 2. 510 2. 485 0. 05570 61. 3 60. 6 60. 95 72. 6 6. 0 79. 0 2. 755 2. 720 0. 05530 66.8 66. 0 66. 40 82. 6 6. 0- 82. 0 3. 125 3. 075 0. 05500 75. 3 74. 25 74. 75 U08.77 2.0 90. 0 3. 610 3. 510 0. 03250 86. 3 84.0 85. 15 141. 0 10. 0 90. 0 3. 660 3. 610 0. 06920 87.4 86. 30 86. 85 148. 0 112 50 60 7 0 Mean Temperature,0C Figure 32 Heat Losses-Aroclor 1242 113 W , lb/sec © 0.0325 o 0.0555 • 0.0692 1 70 80 90 100 Mean Temperature,°C Heat Losses-Aroclor 1248 114 APPENDIX C RAW DATA TABLE 8 Height of the Thermocouples above the Packing Support Thermocouple No. Height, cms 1 C I. 2 B. P 3 3. 0 4 8. 0 5 12. 5 6 16. 5 7 20. 5 8 25. 8 9 31. 2 10 35. 8 11 41. 8 12 C O C. I. Thermocouple installed at the liquid inlet to the column B. P. Thermocouple installed below the packing support and is not shielded. C. O. Thermocouple installed at the liquid outlet from the column. _TABLE 9 Steady state thermo-couple reading in millivolts (Aroclor 1Z42) Run Th.Co. Th.Co. Th.Co. Th.Co. Th.Co. Th.Co. Th.Co. Th. Co. Th.Co. Th.Co. Th.Co. Th.Co, No: 1 2 3 4 5 6 7 8 9 10 11 12 A-l 1. 235 3. 160 4. 045 4. 190 4. 215 4. 230 • •4. 230 4. 175 4. 225 4. 205 4. 200 4. 160 A-2 2. 590 3. 685 4/07 5 4. 195 4. 240 4. 230 4. 240 4. 195 4. 225 4. 215 4. 205 4. 170 A-3 2. 565" 3. 610 3. 915 4. 045 4. 060 4. 050 4. 040 4. 015 4. 025 4. 020 4. 020 3. 980 A-4 1. 525 3. 375 4. 225 4. 320 4. 352 4. 380 4. 390 4. 335 4. 380 4. 375 4. 365 4. 320 A-5 1. 470 ' 3. 270 3. 985 4. 105 4. 140 4. 135 4. 140 4. 095 4. 135 4. 120 4. 115 4. 050 .A-6 1. 205 2. 960 3. 420 3. 565 3. 580 3. 475 3. 550 3. 405 3. 49 5 3. 47 5 3. 470 3. 420 A-7 1. 220 3. 085 3. 835 4. 015 ' 4. 015 4. 010 3. 985 3. 905 3. 975 3. 950 3. 940 3. 850 A-8 1. 610 3. 230 3. 750 3. 765 3. 790 3. 740 3. 730 3: 675 3. 735 3. 730 3. 725 3. 690 A-9 1. 640 3. 270 3. 835 3. 950 4. 025 3. 970 3. 950 3. 880 3. 950 3. 935 3. 930 3. 870 A-10 1. 660 3. 390 4. 005 4. 150 ..4. 195 4. 190 4. 195 4. 140 4. 195 4. 185 4. 190 4. 130 A-ll 1. 675 3. 465 4. 195 4. 290 4. 320 4. 330 4. 340 4. 285 4. 340 4. 340 4. 340 4. 340 A-12 1. 770 3. 59 5 4. 220 4. 330 4. 360 4. 375 4. 395 4. 370 4. 395 4. 395 4. 395 4. 385 A-13 2. 700 3. 720 4. 040 4. 110 4. 155 4. 135 4. 130 4. 080 . 4. 115 4. 110 4. 100 4. 020 A-14 1. 960 3. 510 3. 918 4. 030 4. 040 4. 027 4. 020 3. 970 4. 200 4. 008 4. 015 4. 000 A-15 1. 885 3. 680 4. 160 4. 270 4. 310 4. 305 4. 310 4. 230 4. 310 4. 805 4. 325 4. 260 A-16 1. 735 3. 740 4. 260 4. 305 4. 340 4. 330 4. 325 4. 270 4. 315 4. 310 4. 315 4. 300 116 o in o o o m o in o o o o o o in in o o o vO i— ON ON I-H (NJ oo in i o in in 00 sO in in o i—t U —I r- NO ON ro CM ro ON ro ON 1 00 1—1 ro o oo rr ON o JC ro IH ro ro rr rr rr ro rr ro rr ro rr rr ro rr ro rr o in in in o o o o in o in in o o in o o in U ON ro 00 ro in CO 00 in r~ r- ro r- in o r~ rr r- r- ON (NJ ON r—1 ON 1 ON ON JC ro ro o ro 00 ro •- rr o H co ro ro rr rr rr rr rr ro rr ro rr rr rr ro rr ro rr o oo o o o o o oo oo o o in in o o o o o o U r~ ro o rr rr ON oo vO ON r- CO i—1 l> in r- OO in 0- t> r- o ro fN) ro o ro ON 1—1 ON OO ro r-H 00 rr ON o JC H ro rr rr rr rr rr rr ro rr ro rr rr rr ro rr CO o in in o in o o oo m LO o o o o in in o m o U o ro i-H rr rr o ro o o in oo 1—1 oo in co 4 oo r- o ro (NJ rr o ro o 00 ON 00 ro f—t ON rr ON o JC H ro ro rr rr rr rr rr rr rr rr ro rr rr ro rr ro o U o in in o ro o in o in in in o m in un in o o oo rr m O0 o ON m oo ro vO rr o ON 00 1—1 ro r- 00 o JC r~ ON ro r-H ro ON ro ON I—1 ON 1—1 ro 1—1 CO ro ON o H ro ro ro rr rr CO rr ro rr CO rr rr rr ro rr ro rr o U m m m in m in o o o o 00 . o o O0 00 ro o m o ro r—t o rr ON rr sO i—\ o sO ro r~ o 00 ON JC oo r- o ro oo ro o ro 00 ON OO ro r-H ON rr ON o ro ro rr rr rr rr rr rr orr rr ro rr rr rr 00 CO rr o U m in in o o in o in o m O in CO o o o in o rr .—1 oo ro o 1—1 ro in in in. 1—1 in 00 jc r- ro os ON rT ON H 00 o 00 00 ro o ro o 00 ro o CO CO rf rr rr ro rT rr rT CO rT ro rT O U o in in in o o in o in o in o in o o in in in JC sO m o rT o co sO rT ro •—i ro rT CO r- 00 o 1 rT CO CO o co 00 rT o co o 00 o 00 . ro — ON CO H ON ro ro rT rT rT rT rT rT rT rr rT rt rT rT CO rT o U in m m in in in in o 00 00 in o in o o o o o rT sO CO p-H JC r~- o CO ON in 00 o o o rT co in in CO ON 1—1 ON CO r- co 00 ro o co o 00 o 00 ro r o H ?- CO rO ro rT rT rT rT rT rT rT rT rT rT rT CO rri ro rT o U CO O o in o o o o o o o in o o in o o o sO ON CO 1—1 i-H rT ON NO rT s£> ro in H oo 00 oo in JC r~ in r- - ro o 00 ON o r- ON cr- sO 1—1 vO r~ ro ro ro rT rT rT rT' rT CO rT ro co rT ro ro rT ro ro o U O O O in o O o o o o o o O O O o O O O i—i O 00 o i-H 1—1 1—t o p—I 1—1 rO in rH o o o JC 00 ro rT r- r~ CO sO in r~ cr- CO o rT in •O TABLE 10 Miscellaneous data (Aroclor 1242) P • Ah Run P Z l o T , l *2 © X No: tank psig psig cms cms cms sees °C A-l 6. 5 .2.3 1. 5 36. 0 80. 0 81.0 950 0.9400 A-2 4. 5 3. 2 1. 5 70. 0 80. 0 82. 0 2852 0.9400 A-3 3. 5 2. 3 1. 5 70. 0 80. 0 81. 5 2560 0. 9400 A-4 7. 3 3. 0 1. 5 36. 5 80. 0 82. 0 1835 0.9200 A-5 5. 6 2. 0 1. 5 35. 0 80. 0 82. 0 2050 0.9200 A-6 5, 0 3. 0 1. 5 35. 0 82. 0 83. 0 1205 0.9290 A-7 6. -8 3. 4 1. 5 35. 0 81. 5 83. 0 1530 0.9290 A-8 9. 0 2. 0 4. 0 40. 0 81. 0 83. 0 1450 0. 9535 A-9 10. 2' 2. 0 4. 0 40. 0 81. 0 83. 0 1410 0.9535 A-10 12. 2 2. 2 4. 0 42. 0 81. 0 83. 0 1250 0. 9535 A-l 1 14. 0 2. 8 4. 0 42. 0 81. 0 83. 0 1130 0. 9535 A-12 14. 8 3. 5 4. 0 45. 0 81. 0 83. 0 1165 0. 9515 A-13 5. 2 2. 0 4. 0 70. 0 80. 5 81. 5 1450 0.9515 A-14 8. 8 2. 0 4. 0 50. 0 81. 5 84. 0 1850 0. 9225 A-15 11. 8 2. 3 4. 0 47.-5 81. 5 83. 5 1210 0. 9225 A-16 13. 3 2. 3 4. 0 43. 0 81. 5 83. 5 1150 0. 9170 A-17 10. 0 2. 0 4. 0 37. 0 81. 5 83. 5 1410 0. 9225 A-18 12. 2 2. 2 6. 0 43. 0 81. 0 83. 0 1280 0.9515 A-19 14. 5 2. 2 6. 0 43. 0 81. 0 83. 0 1170 0. 9515 A-20 13. 8 2. 4 6. 0 56. 0 81. 0 83. 0 1200 0.9280 A-21 12. 8 2. 2 6. 0 55. 0 80. 8 83. 0 1310 0. 9280 A-22 13. 5 3. 2 6. 0 59. 0 81. 5 83. 5 1200 0.9250 A-23 7. 5 2. 0 6. 0 65. 0 80. 6 82. 6 1675 0.9320 A-24 9. 0 2. 7 6. 0 69. 0 80 7 83. 0 1500 0. 9320 A-25 10. 1 2. 1 6. 0 56. 0 80. 5 82. 5 1420 0.9410 A-26 11. 5 2. 1 6. 0 57. 0 80. 5 82. 5 1135 0.9410 A-27 10. 3 2. 3 7. 5 58. 0 81. 0 83. 0 1440 0. 9360 A-28 11. 8 2. 2 7. 5 60. 0 81. 0 83. 0 1305 0.9360 118 (Table 10 continued) A-29 14. 0 3. 0 7. 5 62. 0 81. 0 83. 0 1225 0. 9360 A-30 5. 4 2. 0 7. 5 76. 0 80. 5 82. 5 2255 0. 9360 A-31 7.. 0 2. 1 7. 5 73. 0 80. 5 82. 5 1430 0. 9360 A-32 9-. 0 3. 4 7. 5 77. 0 80. 5 •82. 5 1650 0. 9480 •A-33 14. 6 2. 4 7. 5 44. 0 81.0 83. 0 1180 0. 9515 A - 3 4 14. 6 2. 4 7. 5 50. 0 81. 0 83. 0 1180 0.9515 TABLE 11 Steady state thermo-couple readings in millivolts (Aroclor 1248) Run Th.Co. Th.Co. Th.Co. Th.Co. Th.Co. Th.Co. Th.Co. Th.Co. Th.Co. Th.Co. Th.Co. Th.Co. No: 1 2 3 4 5 6 7 8 9 10 11 12 B-l 1. 550 3. 100 3. 503 3. 813 3. 918 3. 903 3. 900 3. 825 3. 840 3. 820 3. 820 3. 775 B-2 1. 575 3. 200 3. 635 3. 915 4. 010 4. 012 3. 990 3. 905 3. 930 3. 930 3. 905 3. 875 B-3 1. 560 3. 110 3. 310 3. 635 3. 675 3. 747 3. 715 3. 607 3. 615 3. 620 3. 595 3. 590 B-4 1. 500 2. 740 2. 878 3. 458 3. 458 3. 478 3. 47 3 3. 345 3. 385 3. 335 3. 335 3. 310 B-5 1. 475 2. 655 2. 750 3. 065 3. 015 3. 190 3. 195 3. 087 3. 070 3. 070 3. 035 3. 025 B-6 1. 930 3. 450 3. 740 4. 000 4. 105 4, 130 4. 150' 4. 105 4. 140 4. 130 4. 115 4. 075 B-7 1. 875 3. 335 3. 458 3. 860 3. 994 4. 017 4. 005 3. 945 3. 960 3. 945 3. 925 3. 915 B-8 1. 860 3. 260 3. 330 3. 747 3. 827 3. 872 3. 860 3. 815 3. 820 3. 820 3. 795 3. 755 B-9 1. 880 3. 275 3. 360 3. 705 3. 805 3. 855 3. 84 5 3. 775 3. 780 3. 805 3. 765 3-,74 0 B-UO 1. 807 3. 005 3. 015 3. 452 3. 412 3. 543 3. 530 3. 480 3. 47 5 3. 485 3. 455 3. 445 B-ll 1. 780 3. 040 3. 070 3. 365 3. 365 3..49 0 3. 475 3. 365 3. 355 3. 395 3. 380 3. 370 B-12 1. 760 2. 660 2. 785 2. 965 2. 925 3. 190 3. 105 3. 090 3. 090 3. 112 3. 072 3. 060 B-13 1. 693 2. 510 2. 625 2. 87 5 2. 745 3. 000 2. 980 2. 895 2. 910 2. 905 2. 870 2. 845 B-14 2. 140 3. 600 3. 685 4. 022 4. 132 4. 152 4. 187 4. 135 4. 190 4. 160 4. 180 4. 140 B-15 2. 140 3. 610 3. 710 4. 025 4. 105 4. 145 4. 175 4. 113 4. 170 4. 165 4. 175 4. 155 B-16 2. 140 3. 600 3. 650 3. 925 4. 020 4. 105 4. 110 4. 020 4. 045 4. 075 4. 07 5 4. 055 (Table 11 Continued) Run Th.Co. Th.Co- Th.Co. Th.Co. Th.Co.- Th.Co. Th.Co. Th.Co. Th.Co. Th.Co. Th.Co. Th.Co No: 1 2 3 4 5 6 7 8 9 10 11 12 B-17 2. 025 3. 273 3. 440 3. 605 3. 565 3. 665 3. 575 3. 548 3. 540 .3. 500 3. 500 3. 450 B-18 2. 000 3„ 000 3. 105 3. 395 3. 480 3. 565 3. 525 3. 460 3. 420 3. 415 3. 405 3. 400 B-19 2. 035 3. 020 3. 120 3. 410 3. 400 3. 59 5 3. 545 3. 455 3. 450 3. 450 3. 440 3. 410 B-20 2. 030 2. 800 2. 990 3. 205 3. 060 3. 415 3. 340 3. 270 3. 300 3. 330 3. 300 3. 280 B-21 1. 920 3. 120 3. 155 3. 285 3. 175 3. 325 3. 225 3. 165 3. 155 3. 150 3. 145 3. 130 B-22 1. 955 2. 740 2. 870 3. 135 3. 025 3. 245 3. 218 3. 120 3. 100 . 3. 095 3. 097 3. 050 B-23 1. 940 2. 790 2. 955 3. 055 3. 100 3. 195 3. 185 3. 115 3. 120 3. 10 5 3. 085 3. 080 B-24 1. 880 2. 560 2. 69 5 2. 810 2. 59 5 2. 970 2. 865 2. 805 2. 785 2. 830 2. 830 2. 800 B-25 2. 327 3. 615 3. 655 3. 942 4. 085 4. 140 4. 153 4. 082 4. 110 4. 053 4. 065 4. 060 B-26 2. 260 3. 465 3. 555 3. 830 ' 4„00 0 4. 055 4. 065 3. 935 3. 955 3. '9 50 3. 960 3. 930 B-27 2. 210 3. 180 3. 335 3. 600 3. 615 3. 707 3. 690 3. 552 3. 542 3. 590 3. 565 3. 510 B-28 2. 160 3. 165 3. 235 3. 550 3. 575 3. 640 3. 610 3. 500 3. 49 5 3. 550 3. 505 3. 500 B-29 2. 125 3. 000 3. 045 3. 330 3. 380 3. 480 3. 463 . 3. 235 3. 225 3. 320 3. 315 3. 300 B-30 2. 100 2. 800 2. 985 3. 155 3. 200 3. 257 3. 235 3. 090 3. 060 3. 030 3. 090 3. 020 B-31 2. 045 2. 860 2. 89 5 3. 155 2. 950 3. 230 3. 185 3. 105 2. 975 3. 025 3. 045 3. 000 B-32 2. 025 2. 630 2. 725 2. 835 2. 675 3. 125 3. 035 2. 87 5 2. 865 2. 915 2. 89 5 2. 870 B-33 2. 010 2. 775 2. 775 2. 885 2. 565 3. 000 2. 925 2. 775 2. 790 2. 855 2. 815 2. 805 B-34 1. 840 2. 420 2. 510 2. 675 2. 290 2. 860 2. 810 2. 655 2. 575 2 . 670 2. 59 5 2. 590 B-35 2. 245 3. 330 3. 365 3. 760 3. 918 3. 970 3. 970 3. 795 3. 825 3. 825 3. 860 3. 800 A 121 TABLE 12 Miscellaneous data (Aroclor 1248) Run P. P Ah Z Z I tank l 2 X No: o psig psig cms °r, cms cms s e r s B-l 5. 2 1.9 40. 0 , 80. 0 . 82. 0 22950 • 0.9300 B-2 7. 0 3. 4 2. 4 38. 0 80. 0 82. 0 2100 0. 9350 B-3 5. 3 2. 3 2.4 38. 0 80. 0 82. 0 2400 0. 9350 B-4 3. 9 2. 0 2. 4 39. 0 80. 0 82, 0 3100 0.9300 B-5 3. 5 2. 0 2. 4 37. 0 80. 0 81. 5 2420 0. 9350 B-6 11.0 2. 2 4. 4 47. 0 80. 0 82. 0 1400 0.9300 - B-7 10. 0 2. 3 4. 4 47. 0 80. 0 82. 0 1455- 0.9160 B-8 9. 0 2. 3 4. 4 46. 0 - 80. 0 84. 0 3090 0.9160 B-9 9. 0 2. 3 4. 4 46. 0 80. 0 82. 4 1950 0.9300 B-10 '7. 4 2.4 4. 4 45. 0 80. 5 83. 5 2700 0. 9160 B-l 1 7. 3 2. 5 4. 4 44. 5 80. 0 82. 0 1730 0.9300 B-12 5. 3 2. 2 4. 4 43. 0 81. 5 83. 5 2320 0. 9170 B-13 4. 6 2. 5 4. 4 42. 0 80. 0 81.5 2010 0.9230 B-14 14. 5 2. 5 7.4 55. 0 80. 5 ' 82. 5 1210 0. 9370 B-15 14, 9 2. 5 7. 4 53. 0 82. 0 85. 0 1725 0.8930 B-16 14. 3 2. 5 7. 4 55. 0 ' 82. 0 85. 0 1780 0. 9350 B-17 9. 6 2. 6 7.4 51. 0 80. 7 83. 7 2530 0.9400 B-18 9. 0 2. 5 7.4 52. 5 80. 5 82. 6 1800 0. 93 50 B-19 10. 1 2. 6 7.4 51. 0 82. 0 • 84. 0 1640 0.9200 B-20 8. 5 2. 6, 7. 4 49. 0 81. 5 83. 5 1710 0. 8930 B-21 6.9 2. 7 7.4 48. 0 81. 0 • 84. 0 3030 0.9540 B-22 7. 0 2. 5 7. 4 50. 0 82. 0 84. 0 2100 0.9350 B-23 6. 6 ' 2. 5 7.4 49. 0 80. 0 82. 0 2100 0. 9230 B-24 6. 0 2. 8 7.4 46. 0 82. 0 84. 0 2300 0.9200 B-25 14. 4 2. 7 9. 4 57. 0 81. 0 83. 0 1155 0.9350 B-2 6 13. 6 2. 7 9. 4 55. 0 81. 0 84. 0 1900 0.9075 B-27 10. 4 2. 7 9. 4 55. 0 80. 5 83. 0 2000 0-9400 B-28 9. 7 2. 7 9. 4 54. 0 80. 0 82. 0 1620 0. 9370 122 / (Table 12 continued) B-29 8. 5 2. 7 9.4 52. 0 80. 5 82. 7 2000 0. 9120 B-30 7. 2 2. 8 9.4 52. 0 80. 0 82. 0 2020 0. 9400 B-31 6. 7 2. 8 9. 4 51. 0 81. 0 83. 0 2200 0. 9075 B-32 6. 0 2. 8 9.4 50. 0 80. 0 82. 0 2200 0. 9300 B-33 5. 5 2. 9 9-4 49. 5 81. 0 83. 2 2800 0. 9350 B-34 5. 5 3. 3 9. 4 45. 0 80. 0 82. 0 2650 0. 9110 B-35 12. 3 2. 6 9.4 54. 0 80. 0 82. 0 1350 0. 9120 123 APPENDIX D PROCESSED DATA & RESULTS ' TABLE 13 ' i Processed Data(Aroclor 1242) o o Run C i- C C w V, H, H L t LOS No: Sl lb Is ec ml err is BTU/hr A-l 32. 2 99- 9 110. . 59 108. 30 0. 0266 450 16. 0 250 A-2 63. 2 100. 0 107. . 66 106. 74 0. 0266 900 13. 0 526 A-3 62. 6 96. 2 106. . 74 105. 57 0. 0266 - 450 11. 5 496 A-4 38. 9 103. 4 , 111. . 71' 109. 42 0. 0267 900 17. 0 340 A-5 37. 6 98. 2 109. , 30 107. 62 0. 0265 900 15. 0 285 A-6 31. 4 86. 5 108. . 40 107. 58 0. 0262 500 13. 0 142 A-7 31. 7 95.5 111. . 04 109. 29 0. 0262 72 5 13. 5 212 A-8 41. 0 90. 3 113. 95 111. 36 0. 0465 950 12. 5 ' 245 A-9 41. 6 95. 5 115. . 47 112. 19 0. ,0465 950 13. 0 295 A-10 42. 1 99. 2 117. 86 113. 79 0. 0467 950 14. 0 335 A-l 1 42. 4 102. 2 119. 78 115. 10 0. 0467 950 14. 0 363 A-12 44. 7 103. 5 120. 76 116. 04 0. 0469 950 14. 0 1 396 A-13 65. 8 98. 4 108. 72 107. 60 0. 0457 450 12. 5 560 A-14 49. 2 95.9 113. 69 111. 17 0. 0470 1100 12. 0 370 A-15 47. 5 102. 0 117. 39 113. 49 0. 0470 888 14. 0 410 A-16. 43. 8 102. 5 119. 12 114. 46 0. 0468 888 14.. 5 . 380 A-17 38. 6 91.7 115. 22 112. 35 0. 0460 888 12. 5 237 A-18 43. 2 91.8 117. 86 114.07 0. 0582 950 14. 0 275 A-19 44. 2 96. 3 120. 44 li5. 57 0. 0582 950 14. 0 328 A-20 54. 0 102. 4 119. 67 115. 54 0. 0575 950 13. 0 470 A-21 53. 5 100. 6 118. 54 114. 60 0. 0575 1040 13. 0 •448 A-22 57. 6 103. 6 119. 34 116. 15 0. 0571 888 12. 5 515 A-23 61. 1 96. 8 111. 97 110. 29 0. 0565 930 12. 0 485 A-24 66. 3 102. 6 113. 96 111. 55 0. 0563 950 13. 0 600 A-25 53. 9 96. 0 115. 34 112. 48 0. 0575 925 12. 5 412 A-26 55. 0 99. 0 117. 04 113. 81 0. 0573 925 12. 5 452 124 (Table 13 continued) A-27 55. 9 95.3 115. 59 112. 16 0. 0648 950 15. 0 . 420 A-28 58. 7 100. 0 117. 39 112. 93 0. 0645 950 16. 5 490 A-29 59. 4 102. 7 119- 89 •• 115. 20 0. 0643 950 16. 0 522 A-30 73. 0 98. 9 109. 01 107. 92 0. 0630 925 15. 0 620 A-31 62. 2 94. 2 111. 29 109. 44 0. 0632 675 14. 0 470 A-32 72. 4 104. 1 113. 96 111. 30 0. 0627 925 17. 0 675 A-33 45. 8 94. 0 120. 54 115. 17 0. 0656 950 16. 0 • 323 A-34 50. 4 97. 4 120. 54 115. 17 0. 0653 950 16. 0 395 125 • TABLE 14 " Processed data (Aroclor 1248) o o Run C C w ,lb/s ec V, ml H, c: No: h '.A B-l 39. 5 93. 1 108. 72 107.32 0. 0310 900 . 12. 5 B,2 40. 1 95. 2 111. 31 109.42 0.0302 900 16. 5 B-3 39. 7 89. 5 108. 87 107.20 0. 0302 900 16. 5 B-4 38. 3 83. 2 106. 73 105. 62 0. ^0306 900 16. 5 B-5 ' 37. 7 76. 8 . 106. 10 105. 20 0. 0300 675 16. 5 B-6 48. 5 98. 2 116. 44 111.29 0. 0460 900 16. 5 B-7 47. 2 95. 3 115. 22 111. 57 0. 0460 900 ' 16. 5 B-8 46. 8 92. 0 113. 96 110.65 0. 0457 ins lfr. 5 B-9 47. 3 91. 7 113. 96 109.97 0. 0457 1100 16. 5 B-10 45. 5 84. 9 111. 84 109.25 0. 0455 1343 16. 5 B-ll 44. 9 83. 6 111. 71 109.22 0. 0455 900 16. 5 B-12 44. 4 76. 8 108. 87 107. 13 0. 0448 893 16. 5 B-13 42. 8 72. 4 107. 81 • 106.62 0. 0445 675 16. 5 B-14 53. 8 99. 0 120. 44. 113. 72 0. 0617 927 20. 5 B-15, 53. 2 98. 8 120. 87 114.29 0. 0617 1-335 20. 5 B-16 53. 2 97. 4 120; 22 113.85 0. 0615 1 335 20. 5 B-17 50. 7 87. 5 114. 72 111.34 0. 0610 1338 16. 5 B-18 50. 1 85. 4 113. 96 110.76 0. 0614 975 16. 5 B-19 51. 0 86. 0 115. 34 111.87 0. 0610 875 16. 5 B-20 50. 9 81. 7 113. 31 110.37 0. 0608 893 16. 5 B-21 48. 2 79. 6 111. 15 108. 96 0. 0606 1325 16. 5 B-22 49. 0 77. 9 111. 31 108. 94 0. 0610 875 16. 5 B-23 48. 6 76. 8 110. 73 108. 57 0. 0608 900 16. 5 B-24 47. 3 71. 3 109. 88 108. 16 0. 0602 875 16. 5 B-25 57. 3 98. 3 120. 33 114.06 0. 0693 950 20. 5 B-26 55. 9 96. 3 119. 51 112.9 3 0. 0698 1325 20. 5 126 (Table 14 continued) B-27 54. 8 88. 5 115. 72 112. 08 0. 0698 1343 16. 5 B-28 53. 6 87. 0 114. 84 111. 48 0. 0697 900 16. 5 B-29 52. 9 83. 3 113. 31 110. 42 0. 0695 1025 16. 5 B-30 52. 4 78. 1 111. 58 109. 29 0. 0695 900 . 16. 5 B*31 51. 1 77. 1 110. 87 108. 82 0. 0693 950 16. 5 B-32 50. 7 75. 2 109. 88 108. 16 0. 0692 900 16. 5 B-33 50. 4 72. 4 109. 16 107. 73 0. 0691 1018 16. 5 B-34 46. 4 69. 5 • 109. 16 107. 96 0. 0680 900 16. 5 B-35 55. 6 94. 3 117. 98 113. 63 0. 0697 900 16. 5 127 TABLE 15 . Results (Aroclor 1242) L, lb A. M T. T..M. T. Q BTU Q BTU HCU, ft Ua BTU hTft2" °F dF Vhr" ~hr~ hTlP"0 A- :i 1097 150. 89 202. 72 3344 3666 0.. 2350 2910 A- 2 1097 178. 88 206. 45 2229 2215 0.. 2265 3220 A- • 3 1097 174. 92 ' 199. 07 1871 1927 0.. 2458 2461 A- • 4 1101 160. 07 208. 88 3665 3567 0,. 2237 3216 A- 5 1093 154. 22 199- 84 3044 329 1 0 . 2425 2692 A- • 6 1080 138. 11 177. 17 2973 2887 0.. 3292 1599 A- 7 1080 146. 48 194. 39 3335 3375 0 .2531 2417 A- •8 1917 150. 17 186 83 4779 4620 0.. 3301 2738 A- 9 1917 155. 39 193. 73 4866 5077 0,. 2867 3068 10 1925 159- 17 '200. 95 5450 5427 0 . 2788 3430 A- 11 1925 163. 94 • 207.5 5 5994 5697 0,. 2564 4067 j\_ 12 19 3 4 165. 38 209- 43 5787 56 56 0 . 2550 37 31 A - 13 1884 • 179- 7 8, 202. 57 2224 3165 0 . 2663 3120 A- 14 1938 162. 59 197 .3 0 4153 4488 0.. 2733 339 1 A- 15 1938 166. 55 207. 16 5022 527 1 0 . 2545 367 1 A- 16 1930 163. 67 209 28 5290 5620 0..258 5 3988 A- 17 1897 ] 49.2 7 189. 08 4435 4913 0. 312 8 2735 A- 18 2400 :1 5 3 50 186. 76 5388 5712 0.. 3797 2564 A- 19 2400 158. 45 194. 96 5843 6152 0. 3340 3025 A- 20 237 1 172. 76 208. 77 5490 5613 0 2651 4270 A- 21 2 37 1 '170. 69 206 80 5526 557 1 0. 2777 4254 A- 22 2355 177. 08 2 12. 27 5103 5440 ' 0..257 4 4650 A- 23 , 2330 174. 11 200. 51 39 10 4190 0. 2966 3738 A- 24 2322 184. 01 2] 1. 77 4410 4312 0.. 2550 5050 A- 25 2 37 1 166. 91 197. 51 4936 4968 0. 3117 3395 A- 26 2363 ]70. 60 203. 63 4906 5191 0. 2863 3902 128 (Table 15 continued) Run A.M. T. T.M. T. Q BTU QBTU HCU, ft Va BTU L, lb o o o V— L—-— "—7-5- o-rr No: hr" ft F £_ j"[ nr *L F A- 27 2672 168. 08 196. 03 4680 5263 0. 3893 2992 A- 28 2660 174. 83 204. 52 5116 5545 0. 3579 3385 A- 29 2651 177. 89 210. 10 5421 5804 0. 3329 3780 A- 30 2598 186. 71 203. 07 2889 3516 0.3414 3450 A- 31 2606 172. 76 191. 72 3356 4215 0. 3927 2700 A- 32 ' 2586 190. 85 212. 24 39 59 4296 4. 3182 3917 A- 33 . 2705 157. 82 191. 94. 5820 6421 0.4160 2682 A- 34 2705 165. 02 198. 11 5781 6316 0;3822 2995 129 TABLE 16 Results (Aroclor 1248) Run L, lb A. M . T T. M. T Q. BTU Q BTU HCU, ft Ua BI No: hr, ft2 °F °F V hr . L hr hr, f B-l 1278 151. 34 187. 86 2776 3148 0..331 7 1676 B-2 1245 153. 77 192. 20 3038 3159 0,.336 0 1705 B-3 1245 148. 10 180. 79 2689 2837 0,.400 5 1279 B-4 1262 141. 35 168. 67 2095 2588 0,.485 1 910 B-5 12 37 135. 05 159. 96 2249 2201 0 .6159 724 B-6 1897 164. 03 197. 06 4505 4359 0,. 3287 2351 B-7 1897 ' 160. 25 190. 24 4295 4209 0..377 9 1962 B-8 1884 156. 92 185. 21 40,1 5 3922 0., 4225 1716 B-9 1884 157. 10 184. 70 4005 3854 0,,418 2 1702 B-10 1876 • 149. 36 172. 38 3325 3390 ' 0..540 1 1248 B-ll 1876 ' 147. 65 171. 87 3751 3326 0..564 8 1270 B-12 1847 141. 08 1 58. 21 2774 2733 0,.717 9 854 B-13 1835 1 35. 68 153. 49 2457 247 1 0..843 6 729 B-14 2544 168. 98 199. 44 5401 5407 0.,442 8 2126 B-15 2544 168. 80 199. 16 5203 5383 0..456 2 2026 B-16 2 536 167. 54 196. 24 5293 5198 0.,478 8 1925 B-17 2515 156. 38 182. 42 3825 4258 0.,548 0 1613 B-18 2532 153. 95 173. 96 3913 410"-6 0.. 5862 1407 B-19 2515 155. 39 175. 14 3790 4048 0.,594 2 1352 B-20 2507 151. 34 168. 08 3635 3545 0.6959 1164 B-21. 2499 147. 02 166. 88 3265 3590 0. 7098 1130 B-22 2515 146. 21 163. 52 3060 3326 0,, 7763 991 B-23 2507 144. 86 ' 161. 18 3109 32 32 0,, 8071 984 B-24 2482 1 38. 74 151. 99 2780 27 15 ,0227 763 B-25 2858 172. 04 197. 95 5820 5443 0.,485 2 2132 B-26 2878 171. 68 194. 43 4788 5396 0.,501 3 1855 130 Table 16 continued Run, „ A. M. T T.M. T. Q BTU Q, BTU HCU, ft Ua BTU L, lb o„ o„ Vl-ir i-> u i 7T3o 2 hr J No: nr. ft. F F hr hr. ft °F B -27 2878 160. 97 181. 90 4847 4474 0. 5703 1789 B -28 2874 158. 54 178. 99 4009 4421 0.5904 1573 B -29 2866 154. 58 172. 11 3629 4004 0.6759 1319 B -30 2866 149. 45 165. 76 3281 3377 0.8452 1083 B -31 2858 147. 83 164. 37 3378 3468 0.8335 1060 B -32 2854 145. 31 156. 84 2998 3198. 0.9249 918 B -33 2849 142. 52 154. 70 2692 2464 1.0641 811 B -34 2804 ,136. 31 148. 10 2468 • 2944 1. 1055 722 B -35 2874 166. 91 187. 98 4618 5146 0.4621 1969 TABLE 17 Reynolds;; Number (Aroclor 1242) L, lb ^ Mean Temperature Re ii 712 o_, hr. ft F 1090 155 1. 239 1090 160 1. 353 1090 165 1. 455 1090 190 , 2.140 1090 200 2. 310 1090 210 2. 620 1920 155 2. 183 1920 160 2. 382 1920 165 2. 565 1920 190 3. 770 1920 200 4. 070 1920 210 4. 620 2365 155 2.690 2365 160 2. 930 2365 165 3. 155 2365 190 4. 640 2365 200 5. 010 2365 210 5. 580 2650 ,155 3.013 2650 160 3. 287 2650 "165 3. 537 2650 190 5. 200 2650 200 5. 620 2650 210 6. 370 / TABLE 18 Reynolds Number (Aroclor 1248) iD Mean Temperature Re hr, ,£t* °F 1250 145 0. 683 1250 150 0. 779 1250 155 0. 382 1250 160 0. 958 1250 170 1. 076 1250 180 '1.447 1250 190 1. 640 1875 145 1. 023 1875 150 1. 168 1875 155 1. 321 1875 160 1. 437 1875 170 1.763 1875 , 180 2. 170 1875 190 2. 460 2520 145 1. 377 2520 150 1. 570 2520 155 1. 779 2520 160 1. 930 2520 170 2. 370 2520 180 2.915 2520 190 3. 305 2865 145 1.566 2865 150 1. 787 2865 155 2. 022 2865 160 2. 195 2865 170 2.695 2865 180 3. 315 2865 190 3. 760 133 APPENDIX E SAMPLE CALCULATIONS A. CALCULATION OF EXPERIMENTAL RESULTS. Sample calculations for the experimental results of Run number A-5, Aroclor 1Z42 are presented here. 1. Height of the Packing The height of the packing}used for the condensation of steam and for cooling of the condensate to the temperature of the Aroclor, was determined graphically from the temperature profile in the Figure 8 from which H = 15. 0 cms. 2. Number and Height of Condensation Units Inlet temperature of Aroclor to the condenser tj = 37. 6 °C Maximum Aroclor temperature t^ = 98. 2 °C Steam pressure at the column inlet. P^ = 5.6 psig. o . . steam temperature at inlet = 109. 30 C Pressure at the top of the column PQ =2.0 psig. 134 Total pressure drop in the column (45. 1 cms) =5.6-2.0 = 3.6 psi . . Pressure drop in 15 cms = 3. 6 x 15 = 1. 20 psi 45. 1 . . Pressure at height H (=15 cms) = 5.6 - 1.20 = 4.4 psig . . Steam temperature at height H = 107. 62 °C Writing the heat balance for a differential height of the packing in which liquid temperature changes from t to t + dt, and steam temper, ature is ts d Q = w Cp dt = Ua (t s - t) dv or w Cp dt = Ua A (ts-t) dH f " or °[ dH = J Uwa • AC p (ts-tdt ) t.1 Here, w, Cp, Ua and A are constant and therefore H = w Cp f 2 dt t t Ua A Jt s ~ The change in steam temperature in the column t is very small s so much so that it can be very well regarded to vary linearly with t. The equation can be integrated to yield H = w Cp ln / tsl ~ tl Ua A B It\ s,2 - t_2 The constant term on the right hand side of this equation is the Height of Condensation Unit and the other term is the Number of Condensation Units. The constant B is one plus the slope dts "at 135 Thus H = HCU x NCU Here NCU= ln / 109.30 - 37.6 \ 107.62 - 98. 2 / = 2.030 HCU = 15.0 cms = 15. 0 ft 2. 030 2. 03 x 30. 48 i = 0. 2425 ft. 3. Superficial Mass Velocity of Aroclor From the orificemeter calibration curves for h = 1. 5 cms and tank temperature 35 °C, flow rate w = 0. 0265 lb/sec Internal diameter of the column = 4 inches .' . Superficial Mass Velocity L = 0. 0265 x 3600 x 144 = 109 3 lb Px4x4 hour, ft 4 4. Aroclor Mean Temperature Arithmetic mean temperature A.M. T. = 1 /2 (37. 6 + 98. 2) = 67. 9 °C = 154. 22 °F True mean temperature in the column T. M. T. = 1_ THt .dH H Jo Here H = 15 cms Dividing the height in six equal intervals, length of each interval is 136 equal to 2. 5 cms. From the temperature profile, the Aroclor temperature at height H = 2.5 cms is 3. 950 mV or 93. 8 °C H = 5. 0 cms is 4. 050 mV or 96. 0 °C H a 7. 5 cms is 4. 100 mV or 97. 1 °C H =10. 0 cms is 4. 125 mV or 97. 6 °C H = 12. 5cms is 4. 140 mV or 98. 0 °C By Simpson's rule fHt.d H » 2LJ5 ' f 37. 6 + 98. 2 + 4 (93. 8 + 97. 1 + 98. 0) + 2(96. 0+97. 6)] Jo 3 = 2.,5 x 1678. 6 = 1398.75 cm.°C H - T'M-T' =i^5 = 93.25 °C = 199.85 °F 1 5. U 5. Heat Balance A. M. T. of Aroclor = 67. 9 °C Specific heat of Aroclor at this mean temperature is given by Cp = 0. 285 + 0. 000326 x A. M. T. BTU lb, UF. = 0.285 + 0.000326 x 67.9 = 0.307 BTU •Cr• ib, F Rate of heat exchange to Aroclor = w Cp (t - t ) x 3600 x 1. 8 BTU/hour = 0. 0265 x 0. 307 (98. 2 - 37. 6) x 3600 x 1. 8 = 3195 BTU/hour The equation derived from the chart given in reference 19- 137 Heat loss through 15 cms height of the column = 15 x 285 = 95 BTU/hour 45. 1 .' . Total rate of heat transfer to Aroclo/r Q = 319 5 + 95 = 3290 BTU/hour JLJ Now, rate of accumulation of condensate = V = 900 ml/sec P 2050 o ** Density of condensate at 7.5 C = 0. 975 gms /ml . Rate of condensation = 900 x 0.975 gms /sec . 2050 = 900 x 0.975 x 3600 = 3.400 lb/hour 2050 x 453.6 Dryness fraction of steam at atmospheric pressure x = 0.9200 With a reference temperature of 32°F and liquid water, enthalpy of entering steam = H-(l~x) ^ s = 1150, 4 - 970, 3 x 0.0800 = 1072. 8 BTU/lb Enthalpy of condensate at the temperature t 2 / = t x L 8 x 1 BTlL/lb = 98. 2 x 1. 8 - 176. 76 BTU/lb . . Rate of heat transfer from steam Q = 3.400 (1072.8 - 176.76) = 3045, BTU/hour The average of Q and Q is a better estimate of correct rate of JL V heat transfer. Perry, J.H. Ed. , Chemical Engineers' Handbook, 3rd Ed. McGraw Hill Book Co. Inc., p. 275. 138 = 3290 + 3045 = 3167.5 BTU/hour 6. Average Temperature Driving Force and Ua Rate equation for heat transfer in a differential height of packing is dQ = Ua (t - t ) d v s = Ua (t - t) A dH , s on integration Q = /Ua A (t - t ) dH or Q= UaA flt -t)dH =U A (t - t) H J s a s av (t -1) =1 r^t -1) dH 8 AV s H" J0 Dividing the height into six equal intervals, the length of each interval is equal to 2. 5 cms At H = O, t = 109. 30 °C s H = 15 cms, t = 107. 62 °C s Without any appreciable loss of accuracy, the temperature drop in the steam could be assumed to be linear with height. Therefore, t at height H is given by s tg = 109.30 - H (109>3() _ 1Q 15 = 109. 30 - 0. 112 H °C -t, dH =^ ta dH - J(t-. H' * j' HtdH 15 J{109. 30 - 0. 112 H) d H - 1398.75 o 139 109. 30 x 15. 0 - 0.112 (15. 0 x 15. 0) - 1398. 7 5 2 1639.5-12.6 - 1398.75 228.15 cm.°C (t - t) = 228.15 = 15. 21 °C s a v 15.. 0 15. 21 x 1.8 = 27. 38 °F Ua = Qav 3167. 5 x 144 x 30. 48 BTU " ^av 7Tx 4 x 4 x 27. 38 x15.0 hr. ft , °F 4 = 2692 BTU hr/ ft? °F. 7. Reynold's Number For non-circular ducts, equivalent diameter d = 4 x Flow Area e Wetted perimeter For, a height H of the packing, this can be written as d = 4 x Flow Area x H e — " » Wetted perimeter x H = 4- x Total Void Volume Total surface of packing For 3/8 inch Raschig Rings (20) Void volume = 68% 2 and total surface per cubic foot of packing =155 ft. •'• de =,4JE_p__6_8 = 0<01?55ft 155 Reynold1 s number = d^ j_ 140 2 For a value of L = 1090 lb/hr,. ft and an average temperature of 200 °F at which viscosity =35.2 Saybolt Universal Seconds (19) s= 0.026 Stokes (Kinematic Viscosity) = 0. 026 x f> Poise = 0. 026 x 1. 315 = 3. 42 cp". Reynold's Number Re = 0.01755 x 1090 3. 42 x 2. 42 = 2.31 B. CALCULATION OF HCU FROM LACKEY'S AND WILKE'S EQUATIONS Sample calculations of HCU from Lackey's equation (7) and Wilke's equation (9) are given here for Aroclor 1248, at a flow rate L = 1250 lb hr, ft. and T. M. T. = 150 °F. For Aroclor 1248 at 150 °F (19) 6 2 o k = 284. 55 x 10 cal/sec, cm , C/cm. (By linear interpolation} Cp = 0.270 +0.000295 x 66 = 0.2895 cal gm, °C / P = 1.41 gm ml =53 Saybolt Universal Seconds = 0.085 Stokes (Kinematic) 0. 085 x 1. 41 x 100 = 12. 00 cp . 141 6 2 Thermal diffusivity pC = k 284. 55 x 10 cJm /sec Cp^ 0. 2895 x 1.41 -5 2 = 69.7 x 10 elm /sec Surface Tension For water at 25 C , jD^ 0. 997 gm/ml yU.w = 0. 8937 cp - -r- = 72.0 dynes/cm 0 w -5 2. D TT = 2. 5 x 10 cm /sec °2H2° = 12. 00 7V 0.8937 = 13.44 i°w a 0.997 = 0.707 P 1.41 = "V0" -5 * 0.0359 *C 69. 7 x 10 ,crw - 72.0 = 1. 74 15 5 HCU = (HTUJ (_A ) °' 33|DW.) °' 5^°- 555 " °- 152 L . HCU - 0. 65 (13. 44)°' ^'(0. 707)0' 333 (0. 0359)°' 5 (L 74)°' 555-°' = 0. 65 x 1. 49 5 x 0. 08910 x 0. 1894 (1. 74)°' 084 - 0. 1727 ft. — Perry, Chilton and Kirkpatrick, Ed., Chemical Engineer's Handbook 4th Ed. , McGraw Hill Book Co. , Inc. 142 Wilke's equation (9) is 55 0 329 5 554 157 L HCU . / . HCU = 0. 65 x (13. 44)°- "(0. 707)0' 329(0. 0359)0' 5\l. 74)0' 554"°- !" x 3. 09o9 = 0. 65 x 4. 170 x 0. 8922 x 0. 1894 (1. 74)°' °66 ; = 0. 4760 ft. C. BEST EQUATIONS TO FIT THE EXPERIMENTAL RESULTS Form of the equation: HCU = F x ( yU )n (1) n = 1.16 for Aroclor 1248 (From Figure 25) n = 1. 10 for Aroclor 1242 (From Figure 26) F changes with flow rate of Aroclor A sample calculation for the value of F is given here for Aroclor 1248 at L = 1875 lb hr. ft2 At T. M. T. = 200 °F (= 660 °R) HCU = 0. 303 ft (from the best line, Fig. 25) For Aroclor 1248 (19) P = 1. 38 gm/ml fX = 57. 5 Saybolt Universal Seconds = 0. 034 Stokes (kinematic) = 0. 034 x 1. 33 x 100 = 4. 59 £pP. On substitution in Equation (1) with n = 1. 16 1 16 0. 303 = F(4.59 ) ' = F X 5. 86 •• F - 0-03175 Thus best equation to fit the experimental results for Aroclor 1248 143 at L = 187 5 is HCU = 0. 05175 (/A.)1' 16 where is viscosity in centipoise. The values of F (Table 20) for Aroclor 1248 when plotted against L gave a straight line (Fig. 27). The equation of this line was F = 0.02765+ 1.244 x 10"5 L where L is in ... lb 2 hr, ft Thus the best equation for the experimental results for Aroclor 1248 is HCU = (0. 027 65 + 1. 244 x IO*5 L) (yLA. ) ^ where is viscosity of Aroclor in centipoise and L is superficial mass velocity of Aroclor in lb hr, ft2 The values of F (Table 19) for Aroclor 1242 when plotted against L, do not give a straight line. Two straight lines were used to relate the values of F and L. (Fig. 27) for Aroclor 1242. The equations of these lines are F = 0.0535 + 8.90x10" L when L, <- 2290 F =-0,/aZ37+ 6.44 x 10"5L when L > 2290 The best equation to describe the results for Aroclor 1242 is HCU= F (yu)1'10 where JUk is mean viscosity i n centipoise , F is defined by above equations, and L is superficial mass velocity in lb/hr. ft . TABLE 19 Values of F for Aroclor 1242 L, lb hr. ft2" 1090 0.0632 1921 0.0706 2365 0.0786 2648 ' 0.0986 TABLE 20 Values of F for Aroclor 1248 L, lb F hr. ft2 12 50 ' 0.0 4340 1275 0.05175 2520 0.05940 2865 . 0.06330