Studies on the Efficiency of Hot Air Furnace(Part 2)The Heat Balace

Abstract

Experiments were made on heat balance of hot air-furnace at various operating conditions.
Lower calorific value of coal and its feed rate, heating air rate, compositions of exhaust gas and cinder, temperatures of heating air, exhaust gas and furnace wall were measured. Moreover we calculated the effective heat, cinder loss, stack loss and wall loss at steady state operation
1. Effects of heating air rate and feed rate of coal on the efficiency and heat losses were ascertained and expressed in Figs. 9, 10, 12 and 15.
2. As for the air temperature at the exit, we established an empirical formula shown as follows :
t₂=(1.6+1.7F)10³L^-0.68 (F<4.5)
t₂=(5.7+0.8F)10³L^-0.68 (F>4.5)
where F : feed rate of coal kg/hr
L : heating air rate kg/hr
3. Heat balance of the furnace operating at the air rate and temperature of the most widely using, primary roller and re-dryer is shown in the following table.