Two-stage dual fluidized bed gasification: Its conception and application to biomass

The quoted two-stage dual fluidized bed gasification (T-DFBG) devises the use of a two-stage fluidized bed (TFB) to replace the single-stage bubbling fluidized bed gasifier involved in the normally encountered dual fluidized bed gasification (N-DFBG) systems. By feeding fuel into the lower stage of...

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Bibliographic Details
Published in:	Fuel processing technology Vol. 90; no. 1; pp. 137 - 144
Main Authors:	Xu, Guangwen, Murakami, Takahiro, Suda, Toshiyuki, Matsuzaw, Yoshiaki, Tani, Hidehisa
Format:	Journal Article
Language:	English
Published:	Amsterdam Elsevier B.V 2009 Elsevier
Subjects:	Applied sciences Biomass Calcium Dual fluidized bed gasification Energy Exact sciences and technology In-bed gas upgrading Multi-stage fluidized bed Natural energy Tar elimination Dual fluidized bed gasification Biomass Tar elimination In-bed gas upgrading Calcium Multi-stage fluidized bed Pyrolysis Tar Coffee Vegetal waste Bubbling Additive Upgrading Char Gasification Fluidized bed
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Summary:	The quoted two-stage dual fluidized bed gasification (T-DFBG) devises the use of a two-stage fluidized bed (TFB) to replace the single-stage bubbling fluidized bed gasifier involved in the normally encountered dual fluidized bed gasification (N-DFBG) systems. By feeding fuel into the lower stage of the TFB, this lower stage functions as a fuel gasifier similar to that in the N-DFBG so that the upper stage of the TFB works to upgrade the produced gas in the lower stage and meanwhile to suppress the possible elutriation of fuel particles fed into the freeboard of the lower-stage bed. The heat carrier particles (HCPs) circulated from the char combustor enter first the upper stage of the TFB to facilitate the gas upgrading reactions occurring therein, and the particles are in turn forwarded into the lower stage to provide endothermic heat for fuel pyrolysis and gasification reactions. Consequently, with T-DFBG it is hopeful to increase gasification efficiency and decrease tar content in the produced gas. This anticipation was corroborated through gasifying dry coffee grounds in two 5.0kg/h experimental setups configured according to the principles of T-DFBG and N-DFBG, respectively. In comparison with the N-DFBG case, the test according to T-DFBG increased, the fuel C conversion and cold gas efficiency by about 7% and decreased tar content in the produced gas by up to 25% under similar reaction conditions. Test results demonstrated also that all these upgrading effects via adopting T-DFBG were more pronounced when a Ca-based additive was blended into the fuel.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	0378-3820 1873-7188
DOI:	10.1016/j.fuproc.2008.08.007