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

Abstract

Australian coal was gasified at atmospheric pressure in an internally circulating fluidized bed (0.3 m i.d. × 2.7 m high) with a draught tube (0.1 m i.d. × 0.9 m high) and a gas separator over the draught tube. The effects of reaction temperature (780–900°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, cold 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, CO 2 13.2–20.4 and CH 4 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, CO 2 18.9–35.3 and CH 4 1.9–4.4, with a CV of 3.3–5.9 MJ m −3.