FURNACE HEAT BALANCE CALCULATIONS A heat balance of a furnace is a means of determining the thermal efficiency of the process and comparing the relative values of heat losses. A heat balance can be carried out on process, part of process or over a number of processes. A datum temperature is required to be fixed for heat balance in which sensible heat calculations can be referred. the heat balance is done with reference to unit quantity of raw material, main product, time standard fuel of fixed calorific value.

HEAT INPUT ITEMS IN A HEATBALANCE It may contain any or all of the following items: preheat in combustion air. Potential heat in fuel. Sensible heat –preheat in fuel. Exothermic heat of reaction. Sensible preheat of raw materials Total heat of steam (used for atomizing fuel) Heat equivalent of other forms of energy supplied e.g. electrical power for heating, driving pumps and fans.

HEAT OUTPUT ITEMS IN A HEATBALANCE It may contain any or all of the following items: Sensible + latent heat in product. Endothermic heat of chemical reaction. Total heat in flue gases (potential heat of any combustible gases and sensible heat of gases). Sensible heat transferred to cooling water. Sensible heat stored in furnaces structure. Sensible heat in conveying equipment. Total heat in any residue in combustion (potential heat in unburnt carbon in ash, soot, tar, etc., total heat in molten slag, sensible heat in ash) structure loss of heat. Unaccounted figure <5%)

HEAT ITEMS REQUIRED /USED IN A H.BALANCE Sensible heat. Specific heat Latent heat Total heat Potential heat Heat of reaction Heat equivalent

5 EXAMPLE S