Steam air heater

Function

 

Steam air heater is finned tube heat exchanger to heat boiler combustion air (primary and secondary air) by steam extracted from turbine in power plant. Actually, this steam heating system could also be widely used for industrial furnaces, waste incineration plant, fired heater to improve air temperature.

 

Application

 

Generally, thermal power plants adopt steam air heater for two purposes:

 

• Placed before air preheater, SAH heats combustion air in cold season to raise cold end temperature of APH to prevent dew point corrosion and fouling on tubes. In hot season, SAH is put out of operation.
• Speed up startup of coal fired boiler. In a cold start, the unit is warmed only by the heat from oil combustion at early stage. The first coal mill will be put into operation only after hot primary air reaches 150℃. Temperature rise is slow due to cold furnace. During this time, lots of oil is consumed. Steam air heater installed on the bypass of hot primary air into coal mill could be put into operation after boiler purging. It could accelerate warming up process to shorten coal mill startup period. SAH saves money by reducing oil consumption.

 

Principle

 

Steam air heater is tubular heat exchanger, where steam passes through tubes and air passes through casing. Combustion air absorbs the heat from phase change of steam. Steam condensates into water and gets discharged.

 

Features

 

1. Staggered or inline arrangement of fin tube. Compact size, less weight.
2. Steel tube, aluminum or steel fins.
3. Rotatable heating element. When steam air heater is out of operation, it is switched to 90 degree position to minimize windward area and system resistance to reduce energy consumption.
4. Extractable design on request.
5. Detachable header pipe.
6. Modular design, easy installation.