In a cylindrical fluidized bed combustor-pilot plant （25.4 cm-diameter×5.85 m-height）, combustion experiments were carried out with the domestic high ash content anthracite (3400 Kcal/Kg) coal.
The effects of coal mean size （0.49, 0.62 mm）, air velocity (23-76 cm/s) and bed temperature (750-950 ℃) on heat transfer coefficients between either fluidized bed, free-board and vertically immersed cooling tubes, temperature profiles along the bed height and combustion efficiency have been determined. The heat transfer coefficient exhibited a maximum value with air velocity. However, it increased with bed temperature and decreased with particle size.
The temperature profiles along the bed height became flattened with increase of air velocity. Whereas, combustion efficiency decreased with air velocity but it increased with bed temperature.