Heat Absorption in Water-Cooled Furnaces

Based on the furnace heat balance, an empirical “effectiveness factor” is derived for water-cooled surfaces therein, relating the heat radiated by the burning fuel and products of combustion to the furnace-outlet temperature. The value of this factor is calculated from certain experimental data for turbulent horizontally fired pulverized-coal furnaces with bare water-cooled tube walls. For these experimental data, the fraction radiated of the heat liberated in the furnace has also been calculated and is compared with Broido’s curve and with the value calculated by the Orrok-Hudson formula. The method of applying the effectiveness factor to design problems is illustrated by showing the effect of preheated-air temperature upon the furnace-outlet temperature.