Performance prediction of steam gasification of wood using an ASPEN PLUS thermodynamic equilibrium model

Abstract

In this article, an equilibrium model based on Gibbs free energy minimisation is presented for steam gasification of biomass in process simulator ASPEN PLUS. Carbon is assumed as fully converted into product gases and no tar content is assumed to be present in gaseous product. The objective is to arrive at the optimum process conditions of gasification. An analysis on the sensitivity of producer gas composition, lower heating value, combustible gas yield, and first and second law efficiencies on gasification process variables including reactor temperature, pressure and steam to biomass mass ratio is also envisaged. Simulations are performed with wood as the biomass material, based on real gas behaviour for product gases and gasifying medium. The predicted results of the model are compared with another Gibbs free energy model formulated using simulated annealing minimisation algorithm. The present ASPEN PLUS model is validated with published experimental results on steam gasification on a fluidised bed gasifier.