Coal gasification characteristics in an internally circulating fluidized bed with draught tube

Australian coal was gasified at atmospheric pressure in an internally circulating fluidized bed (0.3 m.i.d. X 2.7 m high) with a draught tube (0.1 m.i.d. x 0.9 m high) and a gas separator over the draught tube. The effects of reaction temperature (780-900 degrees C), oxygen/coal mass ratio (0.30-0.53), coal feed rate (5.3-12.1 kg h(-1)) and steam/coal mass ratio (0.30-0.81) on composition of product gas, carbon conversion, cord gas efficiency and gas yield and calorific value were determined. Low-CV gas in the draught tube region and medium-CV gas in the annulus region can be obtained. In the annulus region, the composition of the product gas (vol.%) is H-2 31.8-46.2, CO 18.8-25.6, CO2 13.2-20.4 and CH4 5.3-10.4, with a CV of 8.6-13.2 MJ m(-3). In the draught tube region, the composition is H-2 8.3-19.7, CO 6.7-13.1, CO2 18.9-35.3 and CH4 1.9-4.4, with a CV of 3.3-5.9 MJ m(-3). (C) 1997 Elsevier Science Ltd.