Reactivity of Coal Char with Steam and Carbon Dioxide

Abstract

To develop a simulation-model of the Hokkaishi-coal gasification pilot plant, a kinetic analysis of coal-char gasification was investigated. Experiments were conducted on the elementary reaction of C-CO₂ and C-H₂O.
Taiheiyo char pre-treated at 600°C same as fed-char into the pilot plant was used as the test samples. Samples were gasified in a 28 mmφ small batch type fluidized bed reactor made of quartz.
Reaction rate of the carbon was determined from the observed data of the produced gas.
Both reaction processes of C-H₂O and C-CO₂ were predicted considerably well by a modified mathematical model of unreacted core, namely the rate constant of intraparticle diffusion was corrected dividing by square of unreacted carbon conversion.
The activation energy of the C-H₂O reaction was 31.2 kcal/mole and 38.5 kcal/mole for the intraparticle diffusion and interfacial reaction respectively. And also, the activa-tion energy of the C-CO₂ reaction were 94.5 kcal/mole, and 44.1 kcal/mole respectively.
From the results of measured values dx/dt, it was confirmed that the C-H₂O reaction processed superiorly as compared with the C-CO₂ reaction.