Movement of hot zone and an explanation of processes occurring inside a downdraft gasifier
Abstract
It is crucial to increase the level of understanding of some of the processes that occur in a biomass gasifier to advance the gasification technology. This was seen as a key requirement, as in many experimental and pilot-scale studies this aspect was missing, and in private discussions with a few investigators (from two different companies), this led to many questions about what was actually going on inside the unit, as this was not adequately explained in the literature that they had. In this study, an experimental system was designed, in which a visual section enabled observations of the gasifi cation process to be made at a well-controlled location read. Gasification experiments were performed in a small scale, 21mm i.d. quartz tube gasifier. The biomass consisted of wood pellets (cylindrical, 13mm length x 5mm diameter), and this was packed to a height of 400mm in the tube. The air was fed into the top of the tube under a slight positive pressure of 0.1bar (g) and the flow was varied from 1 to 5 litre/minute (STP). The position and height of the red-hot zone inside the quartz tube could be observed, and the composition of the resulting gas measured. Depending on the air flowrate, the hot zone may move upwards or downwards. This important visual observation provides useful insight into what is occurring inside the gasifier, and the complexity and roles of the various reaction zones in a downdraft gasifier.
References
2. A.V.Bridgwater, A.J.Toft, J.G.Brammer. A techno-economic comparison of power production by biomass fast pyrolysis with gasification and combustion. Renewable and Sustainable Energy Reviews. 2002; 6(3): p. 181 - 246.
3. H.A.M.Knoef. Handbook biomass gasification (second edition). Biomass Technology Group. 2005.
4. M.Dogru, C.R.Howarth, G.Akay, B.Keskinler, A.A.Malik. Gasification of hazelnut shells in a downdraft gasifier. Energy. 2002; 27(5): p. 415 - 427.
5. P.N.Sheth, B.V.Babu. Experimental studies on producer gas generation from wood waste in a downdraft biomass gasifier. Bioresource Technology. 2009; 100(12): p. 3127 - 3133.
6. D.M.Earp. Gasification of biomass in a downdraft reactor. PhD thesis, University of Aston, Birmingham, United Kingdom. 1988.
7. G.D.Evans. Development and operation of an open¬core downdraft gasifier system. PhD thesis, University of Aston, Birmingham, United Kingdom. 1992.
8. J.B.Milligan. Downdraft gasification of biomass. PhD thesis, University of Aston, Birmingham, United Kingdom. 1994.
9. Francisco V.Tinaut, Andrés Melgar, Juan F.Perez, Alfonso Horrillo. Effect of biomass particle size and superficial velocity on the gasification process in a downdraft fixed bed gasifier. An experimental and modelling study. Fuel Processing Technology. 2008; 89(11): p. 1076 - 1089.
10. Chih-Lun Hsi, Tzong-Yuan Wang, Chien-Hsiung Tsai, Ching-Yuan Chang, Chiu-Hao Liu, Yao-Chung Chang, Jing-T.Kuo. Characteristics of an air-blown fixed-bed downdraft biomass gasifier. Energy & Fuels. 2008; 22(6): p. 4196 - 4205.
11. Le Dinh Chien, S.Kolaczkowski, D.W.J.McClymont. Using quadrupole mass spectrometer for on-line gas analysis - Gasification of biomass and refuse derived fuel. Fuel. 2015; 139: p. 337 - 345.
12. Le Dinh Chien, Ngo Thanh Hai, S.T.Kolaczkowski, D.W.J.McClymont. Carbonyl sulfi de presence in syngas stream produced from biomass gasification processes: measurement and calculation. PetroVietnam Journal. 2016; 10: p. 48 - 53.
13. S.Kolaczkowski, Le Dinh Chien and S.Awdry. Equilibrium reactions(s) involving H2S and COS species - consideration of thermodynamics and implications on the biomass gasification process. In Proceedings of the bioten conference on biomass and biofuels 2010. Editors: A.V.Bridgwater. CPL Press UK. 2011: p. 733 - 744.
14. Le Dinh Chien, S.T.Kolaczkowski. Steam gasification of a refuse derived char: Reactivity and kinetics. Chemical Engineering Research and Design. 2015; 102: p. 389 - 398.
1. The Author assigns all copyright in and to the article (the Work) to the Petrovietnam Journal, including the right to publish, republish, transmit, sell and distribute the Work in whole or in part in electronic and print editions of the Journal, in all media of expression now known or later developed.
2. By this assignment of copyright to the Petrovietnam Journal, reproduction, posting, transmission, distribution or other use of the Work in whole or in part in any medium by the Author requires a full citation to the Journal, suitable in form and content as follows: title of article, authors’ names, journal title, volume, issue, year, copyright owner as specified in the Journal, DOI number. Links to the final article published on the website of the Journal are encouraged.
