Biomass characterization and reduced order modeling of mixed-feedstock gasification

Abstract

There has been much effort to characterize and model coal for use in combustion and gasification. This work seeks to delineate the differences and similarities between biomass and coal, with emphasis on the state of the art in biomass pyrolysis/devolatilization modeling. An existing coal Entrained Flow Gasification (EFG) Reduced Order Model (ROM) was expanded to more accurately simulate the gasification of a mixed feedstock of biomass and coal. The GE 2700tpd gasifier was used because it is a widely used technology. The characteristics and state of the art in biomass conversion models were applied in the expanded ROM to model coal-biomass mixture gasification. Biomass has higher oxygen content and lower fixed carbon content than coal. Therefore, as results show, increasing the mass fraction of wood leads to a rise in temperature and drop in syngas heating value and Cold Gas Efficiency (CGE). The oxygen feed stream must be adjusted downward to maintain a constant temperature. Temperature change has the strongest effect on ash slag (lesser viscosity and thickness) while ash composition has a very small effect (greater viscosity and thickness).