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Small Integrated pyrogas and Biogas system
RURAL BIOENERGY:
INNOVATIVE INTEGRATED BIOSYSTEM DESIGN FOR FUEL AND FOOD FROM AGROWASTES.
PAGANDAI V. PANNIR SELVAM *, Rajesh S Kempegowda **
SANTIAGO, BRUNNO HENRIQUE DE S. SANTIAGO,UFAL, Mestrando Engª Química ALMEIDA, LOUIZY MINORA C. A. DE ALMEIDA, Engenharia Alimento *.DEQ/CT,Universidade Federal do Rio Grande do Norte (UFRN),
Departamento de Engenharia Química /CT. Universidade Federal do Rio Grande do Norte, Natal-RN. 59078400. Brazil.
Departamento de Engenharia Química /CT. Universidade Federal do Rio Grande do Norte, Natal-RN. 59078400. Brazil.
Coresponding author: pannirbr@gmail.com e www.ecosyseng.wetpaint.com
**. Rajesh S Kemepgowda, Engineering Faculty Asian University, 89 Moo 12, Highway 331 Huay Yai, Banglamung, Chonburi- 20260 Thailand
Brazil is the leader known for its ethanol biofuel development, but also for biomass charcoal, yet lacks in clean rural bifuel production.This paper deals with the system design for sustainable rural projects developments based on the the bioenergy production from biomass wastes using innovative process equipments design and the process optimization . The main objective is towards developemnt of sustainable small scale clean rural energy production as well as with co-production of hot and cold thermal energies. A detailed porject engienering and ecnomic viability of the integrated system was established after many efforts of developement of several pilot preliminary projects and their analysis.The dynamic material ,energy and cash flow models of the complex integrated food processing and small scale energy productions were initially modeled using excel electronic spread sheet and than upgraded the model into computer aided system for process modeling and simulation using SUPERPRO, Intelligent Inc,.
Economic feasibilities studies using genetics algorithms are under development. The preliminary analysis of cost and investments of the the integrated Biomass utilisation projects which are included in this integrated approach study are: biological aerobic treatment process, methane gas production using anaerobic digestion process, aerobic composting, drying of tropical fruits, effluent treatment ssytems, biogas and syngas production as well as cogeneration energy production for drying and cooling using biogas. These models allowed us in identification of techno-economical and scale up problems.
The results obtained from several preliminary project developments with few case studies are reported for integrated project developments for fuel and food using process and cost simulation models. These models render the process development problem with economic potential objectives to be solved very rapidly and make it possible in optimazation of the integrated system and minimization of residues. Several economic problems related with implementation of the small scale rural energy system for sustained local developments based on tropical fruit production in rural areas are analysed and a concept of the integrated biosystem for micro enterprise has been propsed will be implimented in the north east region of the Brazil.
Key Words:Waste,Energy, Biomass,Syngas , Biogas, Pyrolysis.
- Introduction
The conversion of biomass into valuable products such as fuel methane gas and protein feed have been considered to be important by research centre, the central and state government, industries and financial agents (1-6). Brazil has nearly 126.806.000 tones of total biomass wastes produced per year as it is one of the major producer of agricultural crop such as cashew ,coconut,cassava, soyabean , coffee and sugar cane.The use of this lignocellulosic biomass has the potential to solve the present economic crisis such as third world debt, air pollution due to burning, trash disposal, deforestation, animal feed shortage and migration from rural area.
However, the economic utilization of the biomass waste are handicaped by the technical problems due to the pre-treatments and slow bioconversion process (1-4) involved in biofuel production as well as environmental problem. Economic and ecological utilization of the biomass wastes from tropical fruits such as coconut, banana, cashew nut and cashew fruit processing is still problems as their energy valorization involve very complex system design and operation [1-2]. Brazil is the leader known for its ethanol biofuel development, and also for the biomass charcoal, but yet lacks much regarding the rural energy production. There is a need to decrease the pollutants emitted by these wastes asvery huge quantities, nearly 70% (seventh percent) of total generated, are considered to be wasted in Brazil and this makes necessary to consider different alternative process, renewable energy source and co-product design from these biomass residual. The generation of thermal energy is of great importance in the rural industry for the conservation and quality of the fruit and milk. As the electric energy is the main source used for generation of thermal energy, most small rural industries faces two problems now: one related at the high cost of the electric energy, elevating the production cost; the other, related with the distance of the rural areas to the electricity gird, limiting the access. The biomass can be made into wealth for small scale distributed energy production, which is the main objective of this study. This needs focus on system study of the clean biomass technology , cogeneration of energy and also the sustainable development approach for the small scale energy production from wastes (1-5). The main objective of the present workalso is related to the current research study made on the system design, analysis and optimization tools and methods which made possible to the best value of the input variables and/or model parameters of the complex integrated biomass projects for the total integral utilization agrowastes .The system design for small scale energy production from wastes integrated with small enterprise related to agrowastes involve dynamic system models. This system need to attain economic and ecological viability leading to the sustainable development of rural villages with green energy.The novel flowsheet development for maxium ouput energy and minium wastes is also our main objetive of the present work
2. Methods for generating energy from biomass wastes
In recent years, there has been seen considerable efforts devoted to the search for the best ways to use the potentially valuable of biomass wastes sources for energy production by four diferent main methods, it is possible to order them by the complexity of the processes involved[1-15]: 1 .Direct combustion of biomass; 2. Thermo chemical processing to fuel;3. Biological conversion;4.Combined Anaerobic digestion with pyrolysis. The main product, of some of these processes is heat, which is presently studied for the use for the small scale fruit processing and milk dairy industry to generate heat via metane production besides the need of the generation of "cold" effect, is also necessary, the production of hot water (around 50 ºC to 60 ºC) for cleaning of the facilities and processing equipments.(1) as well as the the referigeration.
2.Pyrolysis: The thermo conversion for rural energy production.
Pyrolysis is the simplest and almost certainly the oldest method of processing one fuel in order to produce a better one. Conventional pyrolysis involves heating the original material (which is often pulverised or shredded then fed into a reactor vessel) in the near-absence of air, typically at 300 - 500 °C, until the volatile matter has been driven off. The residue is then the char - more commonly known as charcoal - a fuel which has about twice the energy density of the original and burns at a much higher temperatures made in almost all rural areas to make charcoal Fast pyrolysis of plant material, such as wood, baggasse or nutshells, at temperatures of 800-900 degrees Celsius are under intensively study with pilot plant scale using sugar cane bagasse.
| Pyrolysis Reactor | Conventional | Present |
| Charcoal yield,% | 30 | 25 |
| Bio oil yield,% | 0 | 35 |
| Wood gas yield | 70 | 40 |
Table 01: Slow Pyrolysis reactor designed to maximize the energy recoverycompared to conventional charcoal making system Napier Elephant grass studied in brasil for the pyrolysis had as little as 10% of the material as solid char and converts some 60% into a gas rich in hydrogen and carbon monoxide. This makes the fast pyrolysis a competitor with conventional gasification methods but like the latter, it has yet to be developed as a treatment for biomass on a commercial scale. Some fast pyrolysis were developed and applied in the rural rea of northeast Brazil for roasting the cashew nuts using wood as energy as low cost social technology in the north east part of Brazil where as the hot cashew nut liquid is used as energy source for fast pyroysis in the large scale processing of cashew nut processing, where the energy consumption is very high and we are able to do inovate the fast pyrolysis of 5mints using mixed Cashewnutshell liquid and used vegetable oil , making possible, very high level of charcoal production
The slow pyrolysis : We are able to make better reactor for small scale charcoal production with characteristic properties listed in Table1 using conventional slow pyrolysis using ceramic kiln. Small scale wood gasification project using simple brick wall construction was successfully demonstrated in several remote rural are as, developed mainly in the decade of 80, now not employed much as it is not competitive with the power generated with Internal Combustion diesel engines an the lack availability of charcoal production as, developed mainly in the decade of 80, now not employed much as it is not competitive with the power generated with Internal Combustion diesel engines an the lack availability of charcoal production.
2.3 Anaerobic biodigestion: The bioconversion method for rural fuel production The gas (Marsh Gas) obtained from the natural waste decomposition process, is a mixture of Methane (CH4) and Carbon dioxide (CO2) .this gas is commonly called as the ‘Biogas’. Anaerobic digestion, like pyrolysis, occurs in the absence of air; but in this case the decomposition is caused by bacterial action. This is a valuable fuel which is in many countries produced in purpose built digesters filled with the feedstock like dung and effluents from the dairy. The input is in batches, and digestion is allowed to continue for a period of from ten days to a few weeks. A well-run digester using plug flow bioreactor design operating at the farm in Brazil produce 200-400 m3 of biogas with a methane content of 50% to 75% for each dry tone of input. The biogas-production will normally be in the range of 0.3 - 0.45 m3 of biogas (60%methane) per kg of solid (total solid, TS) for a well functioning process with a typical retention time of 20-30 days at 32°C. The lower heating value of this gas is about 6.6 kWh/m3. Often the production is given per kg of volatile solid (VS), which for manure without straw is about 80% of total solids (TS). Biogas applications from animal wastes or a large centralized manure processing system are constrained by limited energy needs, storage complications, difficulties in exporting the energy, high capital requirements, and complexities in operation and maintenance.. Many such systems use engine waste heat in Europe, but mostly it is used for anaerobic digester heating .Biogas-fueled engine-driven chillers are probably not suitable for most operations that are needed for fruit processing that would like cooler temperatures than 42ºF to 44ºF for raw material and product storage ,as the cooler temperatures are obtained by direct electric unit.In this work we study the slow pyrolysis for samll enegy generation.
3. Materials and methods Process Flow Sheet: A conceptual design of the bioconversion process was constructed using current laboratory and technical data. (10-15) The flow sheet development was done using Superpro process simulator and other subsystems ( Material Balance and Process Yield: The general flexibility abstract simulation model was used for material, energy balance and production costs calculation of conversion of particular substance and raw material to final product via certain steps (n) and (n-1) intermediate substances. Theoretical conversion factor, the efficient of the conversion, the processing cost of the conversion, the valorization of byproducts and extra cost involved are the parameters used. From this, themaximumproduction cost was obtained asfunction of process conversion efficiency and valorization make simulation with user input. These process models were initially implemented with electronic spreadsheet and latter on SuperPRO 4.9, Inteligen.Inc, and U.S.A. process simulator under window graphical operating system for microcomputer(1) Process Economics Parameters and Costs Estimation: This project model and program had been developed to evaluate rapidly the research and the preliminary biofuel project using limited number ofdata that was obtained from laboratory research, allowing user to have estimates about the economics of manufacturing in different scale of production.In our earlier work, we described the method of development of this model (1). The input of process are:capacity (ton/year), yield, batch or continuos process, high,average automation,maximum,temperature,andpressure,alloy factor of construction equipment and the number of processing steps called functional units. More over the data on reactants and products are: molecularweight, prices, stoichiometric ratio, product type as commodity, specialty or intermediate product. Recently several process simulation software are widely ued for process flowsheet development that can be applied to biomass utilization process, which also focus on the computer aids for engineering process economics. Before making use of these software, several input data and mathematical model were developed first for material balance, preliminary design and process economics. These models and program were tied together into an integrated process design in easy to use electronics spreadsheet computer programs or process simulator. [6] A conceptual design of the bioconversion process was constructed , then the thermoconversion involving pyrolysis and gasification using current laboratory and technical data obtained from lierature. The flow sheet development was done using SuperPro Design, SPD process simulator and other subsystems for this two cenarios Also the integrated sytem of bioconversiona nd thermoconversion are also under detailed study at present.The key process economics parameters used for simulation are based on the data reported by our earlier research works. (1,6) Different process design and simulations were made.(1,15)
4. Results
The Bionversion system :This system is used for milk and fruit processing industry for the conservation using the heat for pasteurization the cashew apple juice. The main equipments used are anaerobic biodigester, the combustion furnace, the heat recovery system using heat exchangers are used for food conservations. The thermoconversion system:This case study made involves the slow pyrolysis system, making the charcoal, the heat is recovered from exit flue gas, where as the second case study involved combined pyroysis to make charcoal as well as gasification to produce gas , which was used for the internal combustion heat engine for combined power and energy recovery.(4-9) for pyrolysis to make charcoal(9,13)
The Cogeneration small energy system:The main assumptions made in the model are related to the inferred value of the solids properties and the use of transfer coefficients for thermal and kinetics constants. The values of these constants assumed are validated by the simulation results comparing it to the real process published results. In the following Figure 1, the complex process scheme of the final case study made based on the design for Environment using computer software. In this work, we designed the flow sheet for the processing the waste and also the whole heat recovery system based on the biomass fuel heating in regard to recirculation of the hot water. From the results obtained, it was observed that the heat transfer thermal fluid is very important design components. In fact, the industrial thermal fluid heater may be a robust substitution for the hot water boiler typically used in a conventional heating system with the wood combustion, gasification and pyrolysis.(9-11).We also designed the process flow sheet (for the processing the animal and fruit waste and also the heat recovery system based on the biomass fuel heating in regard to recirculation of the hot water. From the results obtained, it was observed that the heat transfer thermal fluid is very important design components. In fact, the industrial thermal fluid heater may be a robust substitution for the hot water boiler typically used in a conventional heating system of combustion, and also for gasification and pyrolysis. (9-11)
We also designed the process flow sheet for the processing the animal and fruit waste using anaerobic bioconversion and also the heat recovery system based on the gas for heating and recirculation of the hot water. From the results obtained, it was observed that the biodigester dimension is very important design components. In fact, for the small scale, the biogas combustion system appeared to be very simple that may be a robust substitution for the hot water boiler typically used in a conventional heating system, but with greater energy loss. All the system needs the energy integration to the process and the heat recovery system. In the case studied cogeneration make the project more complex than the other simple system compared to the heat recovery using heat pumps.(6,12) .This not preferd system , but simplee recovery of engine exhaust gas as given in the figure 1.
4.1 Optimum Configuration of integrated Energy system design
Obviously there are many permutations that are available for the combined use of the thermo conversion using pyrolysis and gasification or the bioconversion route. Before we started the detailed case studies, we made with an energy audit of the animal and fruit system both in the production and processing units regarding energy demand and supply. After the material balance of all the solid liquid flows, then we made a tally of all of the energy uses supplied using biomass. The energy and environmental audit is done using three case studies taking into account the energy consumed, the uncertainties of the biofuel supply based on the scale and the efficiencies of biogas wood gas production. The entire integrated system requirement is first analyzed and the process design was achieved from the result obtained by the process simulations and optimizations and the result of several techno economical parameters. Our result as well as the other studies show that significant amount of residues from cattle, goat, poultry are required which are available plenty in rural areas as by the data obtained by our research work which can be supplemented by the grater quantities of cashew apples and fruit waste and residues of the production chain. The result is that export or energy generated from biomass wastes can be made possible economically especially in the rural tropical areas in Brazil. The integrated system design approach used in this made possible using cobined integrated bioconvesrion and thermoconversion procoess determine whether the economics of selling electricity, fuel, the ice, the liquid fertilizer justifies the higher incremental capital cost of the engine-generator, the associated higher maintenance costs, and increased processing costs. The best optimized system has co-products together with the heat recovery using heat pump coupled to the low cost gasoline engine adopted to the biogas. Thus this making the system designed sustainable for rural people food processing and animal production chain and environment too. Thus the system is made both economical and environmentally clean using several simulation runs to optimize the system configurations after making the simulation of the process given in the figure 1 below. Our project is an integration of our two stge solid biodigetor technology and slow pyrolysis process .This later one was adopted from the original conceptual design of BEST Energies Inc., which has been recently developed .This is a slow pyrolysis technology which consumes biomass waste streams while producing syngas and carbon-rich end products. The syngas is composed of combustible gases including hydrogen, carbon monoxide, methane, and lower molecular weight hydrocarbons, as well as nitrogen and carbon dioxide. This gas is cleaned by a series of unit operations before being recycled back to the plant or exported. A portion of the gas generated is combusted and used as a heat source on the pyrolysis kiln itself. An additional portion of the gas is combusted and used to dry the incoming feed material for pyrolysis. The excess syngas gas represents the net energy output and can be utilized as a fuel for an engine, an industrial boiler, or as a feedstock for down stream processes which refine the syngas into a liquid fuel.
Figure 1. Process flow diagram of combined pyrolysis and gasification process for rural energy production from solid waste from biodigestor (adopted the BEST tecnology, AU) .
OUR GPEC Pyrolysis Outputs:
GPEC's Slow Pyrolysis system creates synthesis gas for electrical generation, charcoal (char) and waste heat for re-use in plant and for export to other users.
- Synthesis Gas
- Pyrogas,(syngas) can be used to dry the incoming feed material, fuel an engine or a gas turbine.
- Syngas can be used as a feedstock for a secondary refining process.
- Syngas can be used as a natural gas replacement.
- Char can be made into:
- Carbon filtration media,Pelletized fuel,Carbon for soil enrichment
Benefits of the optimised integrated Pyrogas and Biogas Plant design
System Optimization using computer modeling and simulation
Following are the tools and area where the intgerated biosystem are applied:- System design work for decentralized energy production small scale rural, agro industrial are under construction;
- Several software tool for the system design, operating for rural sustainable fuel and food are under development;
- Implementation of nonconventional energy integration projects using Biomass as energy source under study for Milk,cashew ,coconut,and sugarcane based agro industries.
5. Conclusions
The detailed process economic analysis are important step towards the solution to these complex process design problems. With this methodology using computer aids, the results obtained in a process and environmental analysis were used as the input information in a new simulation. The bioconversion process is shown to be better than the thermo conversion based on the environment and energy concerns related with the fruit production chain studied, where as from the resource availability and sustainability point of view thermo conversion shown to more economical with relation to bioconversion. The cogeneration system is too complex to apply to rural energy, require trained man power to design and operate but heat pump can be appropriate technology for rural areas with lager energy savings.The combined bioconversion and pyrolysis under studied much more complex , need higher investments and more efficient. Even though very good models are available for business in eletronic spread sheet excel environments, models for microenterprise of rural food producition as well as energy production involve complexity of the dynamic flux of mass ,energy and money . System design work for decentalized energy production for o agroindustrial system are under study to be implemented in rural are in north east of Brazil.Several computacional models with apropriate implementing envioronments and several software tool for the system design , analysis and optimization of the complex sytem design.But the system elements had been sucefully integrated to make possible the dynamic study of the flux of the matertial , energy and cost to make negry from wastes in an economic way.
REFERENCES [1]Pannirselvam PV. et al. Process, Cost modeling and simulations for integraded project development of biomass for fuel and protein, Journal of scientific and industrial research, vol.57, Oct & Nov, Pp. 567-574,1998. [2] Carioca J OB. et al, Biomassa: Fundamentos, Aplicações, BNB, UFC, 1982. [3]Selvam,P.V.P.Desenvolvimento Implantaçãodo Método Monte Carlo de Simulação para Processo de Produção de Reatores, Anais do 10° Congresso Brasileiro de Engenharia Química, Vol. 1, p. 846-851, São Paulo. 1994. [4] Carioca, et al. Energy from Biomass-Impact of Science on Society, nº 148, 1988. [5] Dale, Bruce E., Biomass refining: protein and ethanol from alfalfa, Ind. Eng. Chem. Res. Dev., Vol. 22, no 3, p. 466-472, 1983. [6] Rud, D Estrategia Wen Ingeniera de Processo. Ed. Alambra, Madri-Espana, 28, ’76. [8] Nguyen, Q A., Saddler, J. N., (1991), An Integrated Model for the Technical and Economic Evaluation of an Enzymatic Biomass Conversion Process. Bioresource Technology, Vol. 35, N. 3, p. 275-282. [9] Hall D., Rosillo-Calle. Biomass for energy. Renewable Energy. Sources for Fuels and Electricity. Island Press, 1992. [10] Thomas, S.. Evaluation of Plant Biomass Research for Liquid Fuels (Brighton, Science Policy Research Unit, University of Sussex), report, 2 vols. 1990 . [11] Williams, R. H. Biomass gasifier/gas turbine power and the greenhouse warming, presented. EA/OECD seminar, OECD Headquarters Paris 12-14, April ’89, 1989 [12] Williams, R. H., and Larson, E. D. Advanced gasification-based biomass power generation, in B.J.Johansson, H. Kelly, A.K.N. Reddy and R.H. Williams (eds.),Renewables for Fuels and Electricity (Island Press), chap. 17. 1992). [13] Prasad SB, Modeling Charcoal Production System Fired by the Exaust of Diesel Engine.In: Energy Conver.v.37, Elsevier Science Ltd.,pp. 1535-1546, 1996. [14] Carioca, J.O.B. & Arora, H.L. Biomassa: Fundamentos e Aplicações Tecnológicas. UFCE, p.220, 1984. [15] MATLEY, J., (1984), Modern Cost Engineering: Methods and Data, Chemical Engineering, Mc Graw Hill Publications, V. 2, p. 265-269, New York. ACKNOWLEGMENT: The finanacial support from National Research Council of Brazil (CNPq/MCT/Agronegcio) and also DEQ,PPGEQ,CT,UFRN all acknowleged. change.
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