Air PreHeaters (APH)

An air preheater (APH) absorbs waste heat from flue gas and transfers this heat to incoming cold air. APHs are typically used in Fired Heaters, Reformers, Process Furnaces, Boilers and other similar equipment to achieve high levels of thermal efficiency. 

There are two main types: recuperative and regenerative air heaters. Esteem designs and supplies recuperative APH systems of the following kinds:

  • Tubular APH (Heat exchanger type - with extruded tubes and end tube sheets)
  • Welded Plate type APH
  • Cast/ Glass Tube APH (arrangement with suppliers)


Issues with usage of APHs

Tube wear -  Due to abrasive flue gases, APH tubes wear out faster on the side facing the gas current. Many advances have been made to eliminate these problems such as the use of ceramic and hardened steel.

Dew point corrosion - The type of fuel used, its sulfur content and moisture content are main factors for dew point corrossion. By far the most significant cause of dew point corrosion is the metal temperature of the tubes. If the metal temperature within the tubes drops below the acid saturation temperature, usually at between 190 °F (88 °C)and 230 °F (110 °C), but sometimes at temperatures as high as 260 °F (127 °C), then the risk of dew point corrosion damage becomes considerable. APH systems typically use Glass tubes at the cold side to reduce imact of acid corrossion.

The Esteem Advantage

At Esteem we use cutting-edge technology and precise fabrication to ensure you receive an APH system with long run life, high efficiency and very low leakages.

A high performance APH system cannot be designed in isolation. Our engineers work with your personnel to understand the requirements and then design the APH system ground up. Due to our experience in design of Fired Heater/ Furnace systems, we analyse the APH feasibility and design keeping in view the performance of the total furnace. We use CFD analysis for duct layout and design for uniform flow over the heat transfer area.

We supply pre-assembled, complete, ready-to-erect APH modules to ensure site work is minimzed.

Contact us to know how we can partner with you for your next APH related project.