Pneumatic conveying of wood powder by using a steam-jet ejector

Wood powder and sawdust are two fuels which will be tested in a pressurized cyclone-gasifier. The gasifier will be a part of combined cycle power plant where a gas turbine is run by the product gases from the gasifier and a steam boiler will use the exhaust gas from the turbine. To inject the fuel into the cyclone, a steam-jet ejector seems to be appropriate due to its simplicity and the possibility of using the steam produced by the boiler for feeding of the fuel. Three types of wood powder with different particle-size distribution have been tested in different ejector geometries. The results show that the steam-jet ejector is suitable as a feeding pump for wood powder and sawdust. For commercial wood powder fuel with particle size below 1 mm, a powder to steam mass flow ratio of about 25 and with coarser sawdust a mass flow ratio of at least 10 can be reached. The pressure gain required to overcome the pressure drop in the cyclone gasifier can be achieved. The relative pressure gain seems to be independent of the size distribution of the particles. (C) 2000 Elsevier Science Ltd. All rights reserved.