Coal-biomass gasification in a pressurized fluidized bed gasifier

ABSTRACT In the framework of a multi-national European Joule project, experimental research and modeling concerning co-gasification of biomass and coal in a bubbling pressurized fluidized bed reactor is performed. The impact of fuel characteristics (biomass type, mixing ratio) and process conditions (pressure, temperature, gas residence time, air-fuel ratio and air-steam ratio) on the performance of the gasifier (carbon conversion, fuel gas composition, non-steady state behaviour) was studied experimentally and theoretically. Pelletized straw and miscanthus were used as biomass fuels. The process development unit has a maximum thermal capacity of 1.5 MW and was operated at pressures up to 10 bar and bed temperatures in the range of 650 °C -900 °C. The bed zone of the reactor is 2 m high with a diameter of 0.4 m and is followed by an adiabatic freeboard, approximately 4 m high with a diameter of 0.5 m. Time-averaged as well as time-dependent characteristics of the fuel gas were determined experimentally. The results will be compared with the gas turbine requirements provided by a gas turbine manufacturer, one of the parmers in the project. The evaluation of the results will ultimately be used to implement and test an adequate control strategy for the pressurized fluidized bed gasifier integrated with a gas turbine combustion chamber