In this work, steam-based gasification is investigated as a technology for fuel gas production for topping combustion in a biomass air turbine (BAT) cycle. For different systems, based on flash or conventional pyrolysis, the characteristics of the product gas quality are studied. The gas composition and the heating value of the produced gas are simulated by changing the main system parameters such as the moisture content of the biomass, the operating temperature and the composition of the biomass.
A model of the gasification process has been developed to evaluate each process. The model is based on mass conservation, the thermodynamic equilibrium of the water-gas-shift reaction and the methane yield during pyrolysis.
A gasification system with flash pyrolysis is identified as a promising technology for fuel gas production for use in topping combustion. The major features of the system are: first, the system provides a gas with a heating value of near to 16 MJ/Nm3 and small amounts of nitrogen gas; second, the application of a water knock out unit eliminates the influence of the water content in the feedstock on the product gas quality; third, the gasification process can be conducted in a tubular reactor within the furnace of the BAT cycle. This reduces the number of reactors and keeps the costs low.