Air Heaters Tubular for steam generator units High efficiency no damage to tube
Tubular type Air Preheater
Air heater and recovery boiler cleaning in power plants is typically carried out with high-pressure water, chemicals or steam.
These techniques, while effective on moderate air-side fouling of heat exchange surfaces, are usually unable to remove the more tenacious deposits that can build up from fly ash, dust and oil in coal fired plants.
Without regular cleaning the heat transfer efficiency reduces, which in turn lowers boiler efficiency and increases a unit’s heat rate.
Severely dirty air preheaters and air heaters can even reduce the unit’s power output. However, PPL Generation’s Brunner Island plant has found a highly effective way around these problems by using pressurized liquid nitrogen.
Function and performance
Plant air heaters improve boiler efficiency by using exhaust flue gases to preheat combustion air. This accelerates combustion by producing more rapid ignition, while also allowing low-grade fuels to be used1.Each 10 ºC (18 ºF) increase in boiler inlet air temperature increases boiler efficiency by 1 per cent, up to a maximum of 10 per cent2.
Configurations can vary widely, but plants typically use either a regenerative Ljungstrom-type rotary heater or a fixed recuperative tubular device. Depending on the configuration, it may also contain a finned tube air preheater immediately after the forced draft fan.
This keeps the primary heater warmer than the dew point, or acid saturation point, in the primary air heater baskets or coils. If this drops below the acid saturation temperature – usually between 87.8 °C and 110 °C, or sometimes at temperatures as high as 126.7 °C – there is a considerable risk of dew point corrosion damage3.
Without preheated air, flue gas products will corrode the heat transfer surfaces, partially block airflow and, in extreme cases, limit the power capacity of the unit. While playing a critical role in increasing boiler efficiency, preheating is only effective if the air heater is maintained and kept clean of air-side fouling
1. Preheated air increases combustion rate and then increases steam generations of boiler.
2. Due to higher temp. of air,furnace temp.increases,so low grade coal can be burnt efficiently.
3. Air heated by heat of exhaust gases.It reduces fuel consumptions.Therefore thermal efficiency of boiler increased.
staggered arrangement /in-line arrangement
staggered arrangement /
Sealing of pipe and plate
Packing heat- resistant material/
a,when gas scours external tube, welcoming smoke tubes have protective tile
b,when gas scours inside tube,wear casing pipes are installed in gas inlet