Slow for Rural Small biomass Energy By joint Project Developmentos of Brazil and Thailand

Mr. Rajesh Kampegowda*, Dr. Pongchan Chandayot Asian University[>>see Location] 89 Moo 12, Highway 331,Huay Yai, Banglamung,Chonburi 20260 THAILAND, www.asianust.ac.th , *Corresponding author : [email protected] Pagandai V Pannirselvam , Maricy Humberto , João Matias Santos Universidade Federal do Rio Grande do Norte - UFRN Departamento de Engenharia Química – DEQ Programa de Pós Graduação em Engenharia Química - PPGEQ Grupo de Pesquisa em Engenharia de Custos - GPEC Av. Senador Salgado Filho, Campus Universitário CEP 59.072-970 , Natal/RN – BRAZIL [email protected] and www..ecosyseng.wetpaint.com

ABSTRACT

The efficiency for carbonization by slow pyrolysis is still low in the current method studied using rice straw in Thailand and cashewnur shell in Brazil, however direct heating process yields better char yield of 17% as compared to indirect heating with 15% process using horizontal metal drum kiln.where as vertical kiln were mainly used in Brazil.Higher yield is made possible from Brasilian cashew nut shell to make oil and char.Carbon and energy balance was also carried out and the results were compared for the direct and indirect process. Burning by indirect draft gives better results like more char, faster process. Direct draft gives less char, but higher quality (higher C and H2). Also a lot of straw is left unburnt in the direct draft kiln, because of bad temperature distribution and flow inside. The kiln design is found to be more suitable for indirect draft rather than direct draft. Both methods still give rice straw that has low calorific value with an output char LHV of 4337 kcal/kg as compared to fresh rice straw of 3412 kcal/kg In the direct heating method output char is enriched to 45% with a still unburnt rice straw left out as compared to indirect heating method with carbon enrichment of 39%. There is a loss of 13% of carbon through the ash in the both the methods. The carbon content in the condensate is in the order of 18.5% for the indirect process as compared to 13.9% in the direct process due to less exhaust and carbon enrichment inside the kiln. There is a loss of 43% of carbon in the exhaust from indirect heating process as compared to direct heating process which is reduced to 26%. The energy balance predicts a heat loss of 14% in exhaust gases..A practical small scale slow pyrolysis project was developed to meet rural energy and heat requirements. to make the clean energy from waste resources possible by the joint project Key words:Slow pyrolysis, rice straw, cashew nut, Brazil, Thailand , Energy and Carbonization

1. INTRODUCTION 1.1 Rational and problem of the biomass waste utlization Rice straw is left as a residue after rice harvesting in Thialand and Brazil which is often get rid off by open burning in the field. Open burning causes many problems such as influence on soil nutrition, soil moisture, pollution and being flammable to nearby structures., where as Casnhew Nut Shell(CNS) in the north east open burning , causes many problems.(1- 7,11).Charcoal making process is being practiced since ages and different types of biomasses are used as raw materials for producing charcoal. Rice straw is produced in the Rayong in Thai , and much is produced in south and northeast of Brazil too. provinces and is currently being burnt in the field or minimized application as fodder for animal. To provide a solution for the biomasss waste in order not to burn and apply back onto the soil to enhance the soil quality and as a conditioner, the traditional charcoal making procedure will be reviewed and experiments would be conducted to evaluate the feasibility of the biomass for charcoal making., bio oil and energy production (5,12). Bio oil , wood gas and charcoal are relatively cheap to produce, compared to fossil fuels, Biomas wastes offer a range of ecological, agricultural, and social advantages. This work describes both the technical problems and the recent results obtained by our joint projects in the field of biomass and slow pyrolysis, inorder to to make valuable products , in a small scale decentralised form in rural area. 1.2 Objective • To evaluate the carbonization technology using rice straw and CSN • Energy analysis and product development based on slow pyrolysis • Detailed listing on the processing requirement for preparation biomass and output • Practical flow sheet development based on slow pyrolysis for rural energy • Integration of process and energy production based on slow pyrolises via flowsheet

2 2. BIOMASS AVAILABILITY AND ITS UTILIZATION IN THAILAND AND BRAZIL Rice straw is an agricultural byproduct, or dry stalks of cereal plants after the nutrient grains have been removed. Straw makes up about half of the yield of a cereal crop such as rice, rye or wheat. In one rai (1600 m2) contains about 320-1600 kg (2-10 t/ha) of straw depending on the nutrition, and environment; For plant nutritious, 1000 kg of straw consists of 6 kg of nitrogen, 1.4 kg of phosphorus, 1.4 kg of sulfur, 17 kg of potassium. Rice straw byproduct biomass source is used in various countries in different applications majority of usage is as an animal feed, bedding for humans and livestock,Where as cashew is is the major crop of semi arid north Brazsil.Rice is the major crop in Thailand, about 50% of the farming land is used for cultivating the rice and its production. Rice straw is byproduct after harvesting the rice. In some of the Asian countries, open burn of rice straw is practiced to enrich the soil contents intern emitting the green house gases into atmosphere ..(6-10)

2.1 Thailand’s and Brazilian Situation on Charcoal Production In addition, Thailand’s charcoal production itself is substantial. Some 7.2 million tons of charcoal are produced per year (Thailand Department of Energy Development and Promotion, 1996). Charcoal accounts for 9% of Thailand’s total energy consumption, and 98% of use and production takes place in rural areas (Thailand Department of Energy Development and Promotion, 1996). Char is the residue of charcoal is consisting of impure carbon obtained by removing water and volatiles out of biomass. Most of the charcoal producers in Thailand use traditional methods to produce charcoal such as pit kilns, rice husk mound kilns. The laws and policy about forestation in Thailand and Brazil does not encourage researchers and charcoal producers to improve charcoal production technology, byproduct studies and input materials. Is the residue of charcoal is consisting of impure carbon obtained by removing water and volatiles out of biomass. Charcoal is soft, brittle, lightweight, black, and porous..Kilns are thermally insulated chambers, in which controlled temperature regimes are produced. Charcoal kilns are to heat wood to the point of pyrolysis to produce charcoal. Different design of kilns have an influence on heat distribution, amount of fuel required, carbonization time, skill required to control the process, cost and maintenance.(11,12)

3 There are many types of charcoal kilns very commun in the both the countries (Figure1-4):

Figure 1 Brick beehive kiln Figure 2 Mud beehive kiln

Figure 4 Rice Husk Mound Kiln Figure 3. Single drum kiln

4 2.2.Charcoal usage forms Commercially, there are three types of charcoal namely lump char coal, briquettes and char coal powder. Lump charcoal is made directly from hardwood material and usually produces far less ash than briquettes. Briquettes (Fig. 5) (Right) are made by compressing charcoal, typically made from sawdust and other wood Figure 5 Lumps of charcoal. by-products, with a binder and other additives.Extruded charcoal is made by extruding either raw ground wood or carbonized wood into logs without the use of a binder.In this project, We also study the use of carbonised charcoal as a binder for briquettes .

2.3.Carbonization Carbonization is a process of converting an organic substance into carbon or a carbon- containing residue. For wood, it means heating wood with restricted air flow, resulting in the production of charcoal as the main product plus gaseous product, condensable liquid and ash..Carbonization has four main stages determined by the temperature attained in each stage; the stages are the following; 1. Endothermic initial dehydration of the wood (200 ˚C) 2. Endothermic pre-carbonization which pyroligneous liquids can be condensed (170-250 ˚C) 3. Exothermic reaction, light and pyroligneous liquid come out steadily (250- 300 ˚C) 4. Drive off volatile components, increasing carbon content of charcoal (300+˚C)

2.3.2 Pyrolysis Pyrolysis means chemical decomposition of organic materials by heating in the absence of oxygen or any other reagents.What actually happens is pyrolysis is same as carbonization but higher temperature, higher energy gaseous products, pyrolysis

5 Figure.6. Pyrolysis Products products are: Charcoal, Pyroligneous acid or wood, vinegar, wood e wood gas..(12) (see figure 6 above ) Key reaction involved with carbonization of biomass is;

Typical biomass → Carbon + moisture

C6n(H2O)5n → 6nC + 5nH2O

Secondary reactions which also occur during the process are;

C + H20 → CO + H2 : 2CO + 2H2 → CH4 + CO2

C + 2H2 → CH4 : C + 2H2O→ CO2 + 2H2

3.METHODOLOGY The rice straw and CNS carbonization report methodology was subdivided into fuel characterization section and rice straw carbonization studies in the pilot horizontal drum kiln. 3.1 Fuel Characterization analysis 3.2 Experimental studies on rice straw carbonization in the pilot horizontal drum kiln 3.1.1 Experimental Design and construction procedure 3.1.2 Method of conducting direct and indirect rice straw process 3.1.3 Parameters Measured in the experimental kilns

3.3. Experimental studies on rice straw carbonization in the pilot horizontal drum kiln 3.3.1 Experimental Design of slow pyrolysis of thailand and Brazil The 200-liter single drum kiln is selected for the rice straw carbonization studies. Currently Thailand utilizes low cost drum kilns for various wood, bamboo based char coal productions. The selection of this design is to understand the current process of rice straw carbonization and develop naval method of operation. The size selected is suitable for small amount of burning, low cost and fabrication could be developed locally. The skill required to control air is not high as suggested, and it is said that it can carbonize even short logs to bamboo leaves. The construction procedures were illustrated with figures as shown in the next section. The 200 liter drum was utilized in the experiemnts carried out with cashew shell nuts.The experimental design objective was to obtain cashew nut shell liquid at the bottom , but operated

6 with direct heating with out air . At the beginning ,the small chimney tube at the center and the perforated conical bottom allowed the top down burning of the cashew shell nuts, then operated as the pyrolysis mode for 8 hours in a closed kiln without air .Due to the better fuel component compared to rice straw, the cashew nut shell have given good yield of more than 60 percent oil content as well as charcoal of 30 percent initial weight of the biomass.The fallowing figure 7a show the detail of the vertical metalic drum used in Brazil for cashew nut shell liquid where as the horizontal one is used in the Thailand for rice straw as shown in then figure 7b.

.2.2 Construction Procedures of small carbonizers

Dimensions: front diameter= 0.6 m length = 0.9 m

Chimney diameter = 0.1 m chimney length = 1.0 m Figure (7a eb)

7 Figure (8a) Setting up location of tank by Figure (8b) 4. Connect the joint and raising the ground to be safe. put a chimney to the joint.

Figure (8 c) Mix the clay with paddy by Figure (8 d) . Put soil on the top of stirring and put it at any connect point. tank use for insulation

Figure 8 (a) to (d) .Construction of the charcoal making kiln

Pilot kilns were prepared at Asian university in close collaboration with the Appropriate Technology Association (ATA) of Thailand. The kiln design is an existing design..The kilns are used to know the low cost carbonization process for the rice straw and to improve the current design by understanding the principles of pyrolysis .The pilot vertical drum kiln was prepared at UFRN, with the help of CNPq with close colaboration of small cashew based cooperatives of the cityTouro, RN Brazil regarding for utilization for cashew proecssing units.. The pilot study was mad on the verticle 55 oil drum as shown inthe the figure abouve adpoted with central

8 chamney with perfurated conical bootom to collect the cnsl liquids,.The design was based on the Nepal beehive brequette making charcoal kiln.(12)

3..3 Method of conducting direct and indirect heating of rice straw carbonization 3.3.1 Indirect heating Method Compressed rice straw sample was weighed and recorded. Prepared kilns were checked for any leaks which could generate heat loss. Few branches (diameter 3 cm) of the wood were placed as a grating support at the at the bottom of the kiln as shown in figures, the height of grate support was 5 cm above the bottom and will act as a convective heat media for the partial oxidation process which will make heat flow inside the kiln become more effective. Most of the rice straw was placed at the deep center. Kiln was closed after placing the rice straw for the carbonization, initial start up firing was done using wood by indirect heating which will transfer the heat to the rice straw with small inlet door. Continuous observations were done to know the transfer of heat, the kiln air inlet size was adjusted based on the changes observed at the exhaust. Inside temperature was measured using the thermocouple to know the raise of temperature. Exhaust form the chimney was also measured which will indicate the temperature at which condensation of the fumes take place. Temperature was recorded every 10 minutes. Recorded the time and noticed carbonization stage changes. The sequential of method of preparation was shown in figures as shown below.

Figure (9a) Figure (9b) Figure 9 (a) and (b) Preparation e Carbonization of rice straw carbonization kilns s

The kiln was continuously observed to see the smoke colour change from blue to light

9 blue, it shows that all the wood has turned to charcoal during that stage the light blue smoke will become clearer. Close inlet, then outlet, make sure there are no leaks, let the kiln cool down for 8 hours.

3.3.2.Direct heating Method Rice-straw was introduced into the kiln with no air gap at the bottom. Initial start up firing was done by firing inside the kiln using hand blower to heat up rice-straw until pyrolysis temperature (500 to 600°C) reached. When the carbonization temperature for rice-straw is reached, the kiln was closed. Intermittently heat was supplied to maintain the temperature inside the kiln at carbonization temperature. Inlet of the kiln was closed tightly by adding the soil at the top to avoid air flow. The carbonization process was continued until all the stages such as drying, volatiles release, carbonization or carbon enrichment and cooled down for 8-9 hours.

3.3.3 Several Practical and Experimental Reactor Design of slow pyrolysis in Brazil

Figure 10: Practical Pyrolysis reactor evolution in Brazil

10 We have studied several slow pyrolysis reactor design that have been practised in Brazil( as shown above figure) as well as the experimental design of small vertical drum metal design . After detailed study of the process, equipments analysed to make several products as the objectives as in the Table 1 , the slow pyrolysis is found to be main process which is an key element of the system design that can make or broke the viability of the project developed to be implemented in several places of the both the countries . The slow pyrolysis is more flexible which is proved to work well with diverse material as biomass feed stocks.( 5,12). One can observe from figure that all reactor are vertical used in Brazil , where as Thailand use horizontal kiln.

Figure.11.Flowsheet of the project for the rural energy by slow pyrolysis of wastes

By joint colaboration with researcher with Thailand , we are curently making progress with respect to slow process reactor design for ruaral area to obtain the bio oil and biochar to make also viable the cogeneration of the small eletrical power as well thermal and cold energy integrated with agroindustry .The flow sheet , under constant improvement, is shown above

11 4.RESULTS AND DISCUSSIONS

4.1. Char yield of indirect and direct heat experiments Charcoal yield Char yield is calculated from both methods such as indirect heat and direct heating

Charcoal yield formula;

Mass of condensate m = ρV = 1080 kgm-3*0.2 L *10-3 m3/L = 0.216 kg

Table 2 Summarized Char yield calculation results

Method Ash % Char % Condensate %

Test 1 Direct heat 13.21% 8.73% 8.5%

Indirect heat 8.73% 12.35% 14 %

Test 2 Direct heat 0% 17.3% 12%

Indirect heat 6.25% 15.00% 18.5%

4.2. Mass balance and Energy balance 4.2.1.Carbon balance The process balance was conducted to know the input and out put mass yields. The input for the process is biomass and to start up it needs the air for the partial combustion. The products from the carbonization kiln are char, exhaust gases, condensate and the ash. All are experimentally found values. Carbon content of the fresh straw was measured by the CHONS analyzer, the mass content of carbon per kg is about 33.6% in the initial fresh rice straw. Carbon balance was compared for the sample calculation of 100 kg rice straw for both direct and indirect heating methods. Initial rice straw consists of 33.33% of carbon from the ultimate analysis. The carbon out put was balanced in the char coal, exhaust gases, condensate

Direct heating Carbonization process

12 17.3 kg of charcoal 45.36% of C, 59.42% of O 2 1.22% of H 0% of N2 2,

7.7 kg carbon 100 kg of rice straw 33.6% of C, 86.08% of O , 2 Exhaust gases 8.95 5.54% of H ,0% of N kg Carbon 2 2

100 kg rice straw Kiln 33.6 kg 4.67 kg of carbon in carbon Condensate

17.22 kg of Ash 13.22% of C 2.2 kg carbon Un-burnt 10.08 86,08% of O in ash 2 kg carbon 0.7% of H 2 0% of N 2 Figure 12. Estimated Carbon balance for rice straw direct heating carbonization Process

Direct heating Carbonization process

15 kg of charcoal 5.9 kg carbon 39.36% of C, 59.42% of O 2 1.22% of H 0% of N2 2, 100 kg of rice straw 33.6% of C, 86.08% of O , 2 Exhaust gases 14.96 5.54% of H ,0% of N kg Carbon 2 2 100 kg rice straw carbonization 33.6 kg 6.21 kg of carbon in carbon Condensate

17.5 kg of Ash 2.32 kg carbon in 13.22% of C ash 86,08% of O 4.2 kg 2 0.7% of H carbon 2 0% of N 2 Figure 13 . Estimated Carbon balance for rice straw indirect heating carbonization Process

13 The results were show in figure for the carbon input and output balance. The fresh rice straw was subjected to the CHONS elemental analysis, from this measured carbon content is about 33.33%. The output char was analyzed to know the elemental composition, the output char has the carbon content of 39.9% may be due to unburnt volatile content in the indirect heating method, this shows that it needs more residence time and controlled condition of temperature. In the direct heating method output char % is enriched to 45% with a still unburnt rice straw left out. 4.3 Energy balance Energy balance was carried for the kiln by using the measured calorific values of the rice straw and char. The basis for the calculation is 14 kg input. The input and output heat balance was carried out for the kiln as show below. The results are shown in the input output box model. There is large un-accounted heat loss due to several factors some of the heat energy loss itself due to the kiln heat losses in terms of start up energy as well as wall heat losses. The indirect method loses energy content of 19 % as compared to 11.4% through exhaust.The energy balance predicts a heat loss of 14% in exhaust gases heat losses as in indirect heating as compared to 11% loss in the direct heating process.There is a loss of un-accounted heat loss in the both methods which is accounted as 48.1% for direct heating as compared to 38.1% for indirect heating. This shows kiln design is more suitable for the indirect heating process.

50.0% 48.1% 45.0% 38.5% 40.0% 35.0% 30.0% 25.0% 22.0% 19.3% 19.0% 20.0% 12.4% 15.0% 11.4% 7.9% 9.8% 10.0% 5.9% 2.9%

Energy distribution in % in distribution Energy 5.0% 2.8% 0.0% Energy Energy Energy Energy Energy % un content in content in Content in Content in content in accounted Char coal MJ exhaust Condensate Ash Unburnt straw losses

Direct Heating Carbonization porcess Indirect Heating carbonization process

Figure 14. Energy balance comparison for direct and indirect heating methods

14 Mode Conditions Liquid Char Gas Fast pyrolysis moderate temperature, short 75% 12% 13% residence time particularly vapour Carbonisation low temperature, very long 30% 35% 35% residence time Gasification high temperature, long residence 5% 10% 85% times

Table 3.Typical product yields (dry wood basis) of the proposd project by different modes of pyrolysis of biomass waste

5.CONCLUSIONS Using vertical cylinder.Carbon and energy balance was also carried; the results were compared for the direct and indirect process. Burning by indirect draft gives better more char, faster process., Direct draft gives less char, but higher quality (higher C and H2). Also a lot of straw left unburnt in the direct draft kiln, because of bad temperature distribution and flow inside.The efficiency of carbonization (percentage of carbon stored in charcoal) is still low from the current methods, however direct heating process of horizontal metal kiln yields better char yield of 17% as compared to indirect heating with 15% process., where as very good resultas are obtaine on the pyrolysis og cashew shell in Brazil. The kiln design might be more suitable for indirect draft rather than direct draft. Both methods still give rice straw charcoal that still has low calorific value.,The calorific value of output char yield was 4337 kcal/kg as compared to fresh rice straw of 3412 kcal In the direct heating method output char % is enriched to 45% with a still unburnt rice straw left out as compared to indirect heating method with carbon enrichment of 39% . There is a loss of 13% of carbon through the ash in the both the methods.. The carbon content in the condensate is in the order of 18.5% for the indirect process as compared to 13.9% in the direct process due to less exhaust and carbon enrichment inside the kiln. There is a loss of 43% of carbon in the exhaust for indirect process as compared to direct process which is reduced to 26%.

The cashew nut shell via slow pyrolysis has given good yield of more than 60 percent oil content as well as the charcoal of 30 percent initial weight of the biomass using vertical Kiln, but needed detailed experiments . The energy balance predicts a heat loss of 14% in exhaust gases heat losses as in indirect heating as compared to 11% loss in the direct heating process There is a loss of un-accounted

15 heat loss in the both methods which is accounted as 48.1% for direct heating as compared to 38.1% for indirect heating. This shows kiln design is more suitable for the indirect heating process. The simplified flow diagram ,using experimental slow pyrolysis based energy production flow sheet needed for rural heat and cold energy requirements, has beeen constructed by joint collaboration of Thailand and Brazilian researchers..Internet has enabled the colaborative technical exchange of the information for the project development 5.1.Future Recommendations

This research needs further experimental investigations to develop good rice straw amd CNS carbonization process and kiln technology which could be easily implemented for char and , recovery of bio oil to make decentralised rural power. Pilot plant study based on the flowsheet and economic modeling and optimization had very good perspective for the both the countries . Interative exchange of information need to given more important in future with good perspectives

6.REFERENCES/ ACKNOWLEDGEMENTS 1. http://aopdm01.doae.go.th 2. http://en.wikipedia.org 3. http://www.sec.psu.ac.th/web-board/?pid=view_replies&thread_id=422&forum_id=7 4. Aj. Rajesh Kempegowda, Dr. Pongchan Chanday, Butchaya Gadde for Experiment data recording assistance. 5. Charles Y. Wereko-Brobby Essel B.(1990) Hagen..Biomass conversion and technology: 6. TANAKA INEKO, HOYANO AKIRA, NAGASAWA YOSHIHIRO, OKUMURA AKIO (Oemuken) (2001) Journal of Architecture and Building Science VOL.116: Application of a breathing wall using rice straw charcoal. Thermal and moisture characteristics by (Tokyo Inst. of Technology, Graduate School) 7. Pari-Hendra-Dadang (Forest Products Technology Research and Development Center) (2004) Charcoal production for carbon sequestration: 8. V. Assavaittiprom & G. Chavalrut (2007): Experimental Report On Gasification Stove, Asian University

16 9. Asia Regional Cookstove Program, Indonesia & Appropriate Technology Association, Thailand (2007): High Quality Charcoal and Briquetting Seminar 10. National Risk Management Research Laboratory, Triangle Park, NC 27711 (1999) Greenhouse Gases From Small-Scale Combustion Devices In Developing Countries : Charcoal-Making kilns in Thailand 11. Pannirselvam.P.V...Characterization of residuos ,in Recycling Process human Food and Animal feed from Residues and Resouces,UFC/BNB,, Brazil,(2000). 12 Pannirselvam P.V.Quimica de biomassa, in Biomassa :Fundamentos e applicaçoes, UFC/BNB,, Brazil,(2000)., Ackwolegment:The autors wish to thank both the university , cnpq as as well as the central governments for the research of this joint project developments

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