Master Thesis PresentationSchool of Sustainable Development of Society and Technology Master Program: Quality in Process Technology Course: Methods in Quality in Process Technology Examiners: Sven Hamp, Lena Johansson Westholm Supervisor: Prof. Erik Dahlquist Spring, 2011

High Quality Methane Production through biomass gasification.

By Muhammad Nauman Yousaf

Background• World Energy demand is on rise like always.• Fossil fuels are the main contributors in

meeting these demands as more than 85% of energy needs are fulfilled by crude oil, Natural gas and Coal.

• Alternative energy resources (e.g. Wind, Solar, Wave power etc.) have been explored but still cannot present for such a large extent.

Graph 1, World fuel consumption by fuel type from BP Statistical Review of World Energy June, 2010.

Biomass as an Alternative• Worldwide biomass ranks fourth as an energy

resource, providing approximately 14% of the world’s energy needs; biomass is the most important source of energy in developing nations, providing; up to 35% of their energy [Ayhan Demirbas et al.].

Biomass gasification in Sweden

• The Swedish Energy Agency (Energimyndigheten) has among other decided to financially support the building of a pilot plant for the gasification of biomass to green energy gas with a new technology called WoodRoll®.

Focus

• In this study, I have looked for the methane production during biomass gasification.

• Reason behind such an aim is the experimental data obtained by Dr. Erik Dahlquist during his work on dry black liquor gasification process with direct causticization for paper and pulp industry.

Methodology• I have performed chemical equilibrium calculations at

different operating conditions to see the effect of each parameter on the gas composition. The main motive was to produce high percentage of methane in the product gas out of gasifier.

• I have used Aspentech’s Aspen Plus process simulator for generating process simulations and then compiled the results in an MS Excel sheet.

• Extensive literature review was done about modeling of gasification in Aspen and also about biomass gasification in general along with separation techniques that could be used to separate methane from the main product stream.

Figure 1, Cortus WoodRoll Process diagram [Cortus AB et. al.].

Modeling

Assumptions • Process is steady state and isothermal. • Biomass devolatilization takes place instantaneously

and volatile products mainly consist of H2, CO, CO2, CH4, higher hydrocarbons and H2O.

• Char particles are spherical and of uniform size and the average diameter remain constant during the gasification, based on the shrinking core model.

• Char only contains carbon, hydrogen, oxygen and ash.

Biomass Characteristics

Results

Effect of Steam/biomass ratio.

Effect of Steam/biomass ratio.

Effect of Temperature

Effect of Pressure

Graph 4, The effect of temperature on the composition of the product gases at 0,21 steam to biomass ratio and constant temperature 1373 K.

Separation

At the moment only concise literature review have been done about the gas separation technologies that are available and suite our purpose,

• Cryogenic• Membrane Separation• High-pressure Swing Adsorption Process

Conclusions • From the results that we have obtained in the simulations and that of experimental

data from pilot and actual plants, we can defiantly say that the methane production inside the gasifier at lower temperatures is quite possible and should be purse.

• If we run the gasification process at higher temperatures as in the case of Cortus WoodRoll gasifier, the amount of CO2 and CH4 will be considerably low and production of low tar content syngas is possible.

• Steam is a better choice as an oxidizing medium as compared to O2 and Air due to obvious effect of their use on the LHV and quality of the produced syngas.

• As in the case of Cortus WoodRoll gasifier, the possibility of running it at low temperatures is not an option, we would have to cool down the gas in such a way that the producer gas further react to give CH4 with or without the help of any appropriate catalyst.

• As the pilot plant under construction at Köping, we will be able to get the experimental data from that plant in future and can observes and solve the technical difficulties that may come in the process.

• These results are also in agreement with the results obtained by other studies and with study of Erik Dahlquist et al. on the black liquor gasification in a pilot plant

References 1. Ayhan Demirbas, Combustion characteristics of different biomass fuels, Elsevier Inc. (2010). 2. Aandre Faaij, Rene Van Ree, Lars Waldheim, Eva Olsson, Andre Oudhuis, Ad Van Wijk, Cees Daey-Ouwensll and Wim Turkenburg, Gasification of biomass wastes and residues for electricity production, Elsevier Inc. (1997). 3. A. Gomez-Barea, B. Leckner, Modeling of biomass gasification in fluidized bed, Elsevier Inc. (2010). 4. BP Statistical Review of World Energy, June 2010 5. Chun-Yang Yin, Prediction of higher heating values of biomass from proximate and ultimate analyses, Elsevier Inc. (2010). 6. Dong Li, Sun-Tak Hwang, Preparation and characterization of silicon based inorganic membrane for gas separation , Journal of Membrane Science, Volume 59, Issue 3, 15 July 1991,Pages331-352. 7. Energy Information Administration/Short-Term Energy Outlook—March 2011. 8. Erik Dahlquist and Andrew Jones, Presentation of a dry black liquor gasification process with direct causticization, Tappi Journal vol. 5: No. 5, June 2005. 9. J.W. Gibbs, “A Method of Geometrical Representation of the Thermodynamic Properties of Substances by Means of Surfaces,” Transactions of the Connecticut Academy of Arts and Sciences 2, Dec. 1873, pp. 382-404 (quotation on p. 400). 10. Jose Corella, Alvaro Sanz, Modeling circulating fluidized bed biomass gasifiers. A pseudo-rigorous modelfor stationary state, Elsevier Inc. (2004). 11. Mehrdokht B.Nikoo & NaderMahinpey, Simulation of biomass gasification in fluidized bed reactor using ASPENPLUS, Elsevier Inc. (2008). 12. Narges Bagheri, JalalAbedi , Adsorption of methane on corn cobs based activated carbon by Chemical and Petroleum Engineering, University of Calgary, 2500 University Drive, NW,Calgary, ABT2N1N4, Canada. 13. Reynolds WC. The element potentials method for chemical equilibrium analysis: implementation in the interactive program STANJAN. Department of Mechanical Engineering, Stanford University; 1986. 14. S. Jarungthammachote, A. Dutta, Equilibrium modeling of gasification: Gibbs free energy minimization approach and its application to spouted bed and spout-fluid bed gasifiers. Elsevier Inc. (2008). 15. Thomas Reed and Ray Desrosiers, The equivalence ratio: The key to understanding pyrolysis, combustion and gasification of fuels. www.woodgas.com. 16. X.T. Lia, J.R. Gracea, C.J. Lim, A.P. Watkinson, H.P. Chen, J.R. Kim, Biomass gasification in a circulating fluidized bed, Elsevier Inc. (2003).

Acknowledgments First of all I would like to thank my Lord Almighty for giving me the strength to carry out this work. Then, I would like to use this opportunity to thank all those who have helped me and guided me throughout this study. I would also like to mention the names of some people especially:Professor Dr. Erik Dahlquist, Dr. Hailong Li, Sven Hamp, Lena Johansson Westholm, Rolf Ljunggren,Marko Amovic. Last but not least, My Family and Friends.

Thank you!!If you need further information about the topic,please feel free to contact me at my emailaddresses;

• myf10002@student.mdh.se• nauman.yousaf@live.com

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