Gasification of two coals was carried out in a batch feed fluidized be
d reactor at atmospheric pressure using steam as fluidizing medium. A
model of coal gasification was developed, incorporating a first-princi
ples model with a neural network parameter estimator. The hybrid neura
l network was trained with experimental data for the two coals and gav
e good performance in process modelling. A parameter for the overall r
eactivity of char, namely 'active char ratio' (ACR), was identified by
the neural network, as a function of gasification time and temperatur
e. The ACR profile showed a strong dependence on coal type. Other para
meters estimated by the neural network also reflected distinct charact
eristics of the two coals. (C) 1997 Elsevier Science Ltd.