On a certain method of power boiler blast air pre-heating

Abstract

The method for preliminary heating of boiler blast air has been developed; as per this method, the air before being blown to boiler air heater is pre-heated with exhaust natural gas combus-tion products in surface heat exchanger with combustion products cooled below dew point temperature. It is suggested to use water vapor condensate produced by this process as heat system make-up water. Thermal calculation for condensing heat exchanger installed down-stream of BKZ-420-140 NGM power boiler is made, as a result of the calculation, the following parameters were obtained for different values of ambient air: heating power of heat exchanger; consumption of exhaust gases for pre-heating of boiler blast air provided that they are cooled below dew point temperature; proportion of exhaust gases transferred to heat ex-changer; consumption of water vapor condensate produced from gas fuel combustion prod-ucts; temperature, moisture content and dew point of exhaust gases on exit of boiler unit; in-crease in boiler fuel consumption coefficient due to operation of condensing heat exchanger; heat transfer coefficient. Cost effectiveness due to pre-heating of BKZ-420-140 NGM boiler blast air in condensing surface heat exchanger at Samara Power Station has been determined.