44.揮発性成分/チャー非共存・共存下における褐炭の水蒸気ガス化特性

概要

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Steam gasification of a brown coal was performed in an atmospheric bubbling fluidized-bed reactor with continuous feeding of the coal. The gasification converted no more than 28-71%-C of the nascent char at 1120-1223K. The char recovered from the fluidized bed was, nonetheless, steam-gasified completely in another reactor, i.e., in the absence of volatiles from the pyrolysis. Atmosphere created in the fluidized bed thus prevented the char gasification from taking place beyond upper-limit conversion. In the absence of volatiles, nascent char underwent gasification catalyzed by inherent metallic species and non-catalytic gasification in parallel. The non-catalytic gasification was greatly decelerated by the presence of H_2 in the gas phase due to a well-known inhibition mechanism. The inhibition was, however, not so strong as to terminate the gasification. It was rather suggested that much more H-laden carbon was formed through chemisorption of hydrogen from the volatiles in the gas phase, which resulted in prevention of the non-catalytic gasification. In the fluidized bed, char was mainly converted by the catalytic gasification, while the conversion was limited due to deactivation of metallic species within the char matrix and their release from the char.
一般社団法人日本エネルギー学会の論文
2006-10-12