Air Preheaters in Boiler Working, Function & Types

Air Preheaters (APH)

Air preheaters (APH) are shell and tube type heat exchangers used to preheat air which is fed to boilers or furnaces/kilns for fuel combustion. The primary purpose of an air pre heater is to remove waste heat from the flue gases coming out of the boiler.

Thermokrupp Boilers manufactures Air Preheaters and Packaged Type Boilers, the main equipment in Combi Boilers – supplied with boiler as a standard side accessory.

Why is hot air sent into the furnace?

Creating a fire in a boiler furnace requires 3 main ingredients: fuel, air, and ignition. Air is used for combustion of fuel in boilers. Based on the stoichiometry calculations, the correct amount of air along with the excess air is pumped into the boiler furnace for fuel combustion.

Normally, the fuel supplied to the boiler is at normal room temperature and intended for combustion of the fuel; The temperature of the fuel rises from its room temperature to the ignition temperature. So hot air is fed to the boiler, the furnace for fuel combustion, along with increasing the efficiency of the combustion process.

Type of Air Preheaters (APH)

We manufacture different type of air preheaters:-

  • Shell and tube type single pass air pre-heaters
  • Shell and tube type dual-pass air pre-heaters
  • Finned tube air pre-heaters

Function of Air Preheaters

Air preheaters have a shell and tube type construction where the heat from the flue gases is transferred to the air when they come into indirect contact with each other.

Air preheaters consist of a shell where the tubes are arranged in a square or triangular pitch and welded to a tube plate. Depending on the type of operation and ease of cleaning, flue gases and air may be allowed to travel up the shell side or the tube side interchangeably.

Read also: 10 Benefits of Combi Boilers

Thermodyne Boiler Finned Tube Air Preheaters are designed to maximize efficiency by increasing the heating surface area without increasing the space requirement.

Thermokrupp Boilers manufactures Air Preheaters which are customized as per customer requirement.

Our air preheaters are designed in both 1 and 2 passes to extract maximum heat from the flue gases for both the flue gases and the air.

Air Preheater Pros:

  • 2 pass design to extract maximum waste heat from boiler flue gases.
  • It is used to remove waste heat from flue gases leaving boiler exhaust thereby increasing boiler efficiency by 2-3%.
  • It is used to preheat the fuel which further increases the efficiency of the boiler.
  • Payback time is short.

Air Preheater Cons

  • Adding a device or accessory to the flue gas passage causes the flue gas pressure to rise and fall below the line, increasing the size of the induced draft fan.

Buy Air Preheater from Indian Manufacturer: Thermokrupp Boilers: Contact Us

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