Seven different samples of coal chars were gasified with steam in a fixed-bed differential reactor

operating under atmospheric pressure. A generalized kinetic equation for the gasification of coal char with steam was established. Such basic data obtained might be found useful in gasification furnace design work as well as in gasification technology. The initial gasification rate of coal char could be expressed as: (1) The relationship between char conversion x and the rate canstant was found to be: Changes in specific surface area of pores could be obtained from the random pore model introduced by Bhatia and Perimutter: (3) where was a characteristic physical parameter of coal Putting Eq. (3) into Eq. (1)

the generalized rate expression becamedx/dt =KS0PH2o(1 - x) ( 4 ) Integrating Eq. (4) with x = 0 at t = 0

char conversion at any period ought be. x = 1 - exp[ - K S0PH2ot (1 + b/4K S0PH2ot) ( 5 ) Using Eq. (4) rate canstant K could be evaluted from the observed initial gasification rate(dx/dt)x=0 such as (6) Putting K thus obtained at any specific reaction temperature into Eq. (5)

char conversion at any desired interval might be predicted. Calculated values correlated rather satisfactorily experimental results obtained. Further studies revealed that the production rate of carbon-borne gases related to the overall gasification rate of coal in the following manner: (7)