Thermodynamic modeling and analysis of a serial composite process for biomass and coal co-gasification

This paper puts forward a new process for the co-gasification of biomass and coal. The process is divided into combustion stage and gasification stage. It provides thermal energy in the combustion stage and produces combustible gases in the gasification stage. The process is named as serial composite process for biomass and coal co-gasification, because of the biomass gasification react after coal gasification react in the gasification stage. A thermodynamic equilibrium model is established for the process. The model is divided into two sub-models, one is the coal combustion sub-model, the other is the coal-biomass serial gasification sub-model. The coal combustion sub-model is divided into two stages including coal pyrolysis and combustion reaction. The coal-biomass serial gasification sub-model is also divided into two stages including coal char gasification reaction and biomass gasification reaction; the temperature of two stages is different; an empirical equation for the temperature relationship is estimated from the experimental data. The model studies the effects of key parameters on gasification properties, including gasification temperature, s/c, coal/biomass, and predicts the composition of product gas, gas yield, gas calorific value and gasification efficiency of the process. Compared with the dual-fluidized bed gasification process, the process is stable, high gas yield, the medium calorific value gas can be produced. It is a new gasification technology worthy to be popularized.