| FLUE GAS HEAT RECOVERY SYSTEM |
| At the Boiler Station the heat released by burning fuel is utilized to heat water or produce steam. Practically it is not possible to completely utilize this heat energy. The products of combustion from any fuel will result flue gas which is a mixture of water vapours, CO2, N2, O2 and traces of other gases. In case of bagasse fired boilers approximately 4 to 5 times flue gas is produced by burning each ton of bagasse. The spent combustion gases / flue gases are removed from the boiler when the heat transfer reaches its practical limit. A large amount of the heat generated is wasted as exhaust boiler flue gas temperature is around 160-180°C and the specific heat is around 0.3 kcal / kg. So the spent flue gases still hold considerable thermal energy. In many systems, this is the highest single heat loss. This heat energy loss must be recovered to achieve energy efficiency. SED’s FLUE GAS HEAT RECOVERY SYSTEM The energy efficiency can be increased by using SED flue gas heat recovery system to arrest and use the energy in the flue gas. The boiler economy can be made better and waste heat can be recovered in two patterns:
Recovery upto dew point / Sensible heat recovery The spent flue gas energy is used in condensate heating / pressurized heating upto 120-125°C depending upon the flue gas quantity. This heated condensate is flashed depending upon the low pressure heat requirement or can be flashed to the evaporator trains and returned back to heat recovery units at the boiler station. In this way the vapours generated in flash tank are utilized in concentrating the juice of evaporator station. Recovery at dew point In case of bagasse fired boiler, since the sulphur content of flue gas is negligible or almost nil so water content in the flue gas can be condensed and used in the process to recover more heat energy.
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