The feed water preheater is used when fuels containing sulphur are used in combination with an economiser. To prevent sulphuric acid from condensing on the economiser tubes, the feed water is heated to temperatures above the acid dew point following deaeration. Temperatures of 120 – 140°C are required, depending on the sulphur content of the fuel.
Info on Dew point of flue gases
The feed water preheater is designed as a steam heated tubular heat exchanger equipped with the necessary control, safety and display elements.
Simplified system schematics showing integration of a feed water preheater
Feed water preheater
Feed water vessel