30. Economiser
Flue gases leaving the superheater and reheater still contain useful energy. Water from the high pressure feed heaters is heated in the economiser from 252°C to 292°C before it continues to the steam drum. Having given up its last heat in the boiler, the flue gases move on to the air heater.
Pauline says...
The economiser makes use of the heat energy that is still in the flue gas to increase the temperature of the feedwater further before it goes to the steam drum.
