FURNACE HEAT BALANCE CALCULATIONS A heat balance of
FURNACE HEAT BALANCE CALCULATIONS • A heat balance of a furnace is a means of determining 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
EXAMPLES 5
- Slides: 5