Factors affecting steam gasification rate of low rank coal char in a pressurized fluidized bed

A high-pressure bubbling fluidized bed reactor was used to study the steam gasification of coal char under pressure. Indonesian sub-bituminous coal char (Adaro) and Australian lignite char (Loy Yang) were gasified with steam in the reactor at temperatures below 1173 K and at total pressures ranging from 0.1 to 0.5 MPa. The steam gasification rates of the coal chars were determined by analysis of the gaseous products. Activation energies for the steam gasification of the chars were as high as about 250 kj/mol. which suggests that the temperature dependence of the gasification was substantial. The apparent gasification rates under the study conditions were described by a Langmuir-Hinshelwood (L-H)-type equation. Analysis of the reaction kinetics on the basis of the L-H equation indicated that increasing steam pressure effectively increased the gasification rate. (C) 2009 Elsevier B.V. All rights reserved.