Pressurised fluidised bed co-gasification of coal and biomass

Co-gasification of biomass and coal is performed in a 1.5 MWth pressurised fluidised bed gasifier in the framework of a 3 year multinational EU JOULE project concerning research on efficient, environmentally acceptable large scale power generation systems based on gasification technology. Influences of feedstock (biomass component and coal/biomass ratio) and operating conditions (temperature, air factor, steam/air ratio) on gasification characteristics (gas composition, conversion gr;ides) are studied. The gasifier is operated at pressures below 10 bar and temperatures up to 900 degrees C. The gasifier has a 2 m high bed zone (diameter of 0.4 m) followed by a freeboard approximately 4 m high (diameter of 0.5 m). Measurements are used for determining the operating envelope of the installation and validating a mathematical model for emission of environmentally harmful components like fuel-nitrogen derived species. Results obtained in the first part of the project are presented and analysed. A fuel gas of a heating value acceptable for combustion in a gas turbine combustion chamber is obtained at air factors of the order of 0.4. Carbon conversions are well above 80%. Fuel-nitrogen conversion is in-line with other investigations.