Indirect Air Heaters

RCR offers two indirect air heater design configurations; Concentric Shell (CC) and Tubular Type (TT). Being indirect heaters, clean process air is maintained entirely separate from heating exhaust gases throughout the heat exchange process, thus maintaining full hygiene of the heated air. All surfaces in contact with the process air are stainless steel materials.


Process air exit temperatures typically range from 120°C to 430°C and a comprehensive range of standard sizes is available. Client’s specific air flow and temperature requirements are run through proven in-house RCR design programs to select or tailor a model of air heater to suit each application.


Concentric CC Design

CC design is for smaller duties, typically air flows up to 40 tph and where compactness of footprint is also important. The heat exchanger consists of a number of closely spaced shells nested concentrically around a central furnace tube.


Tubular TT Design

For larger duties, RCR offers a heater with a two-pass tubular heat exchanger with process air flowing through tubes and exhaust gases around tubes. Special proprietary design techniques are employed in the heat exchanger to minimise thermal stresses due to differential expansion and to maximise heat transfer for high efficiency. By use of flue gas recirculation (FGR) and physically separate chambers for combustion and heat exchange, RCR heaters can very accurately control the gas temperature entering the heat exchanger. This is critical for ensuring even gas and air temperature profiles and long life of the heater internal components. It is possible to supply two or more process air streams at different temperatures via internal mixing (additional process fans and dampers are required).



  • High hygiene - minimal risk of process air contamination
  • High thermal efficiency – better than steam (or thermal oil-heated) systems
  • Low air side pressure drop - reducing fan power consumption and fan noise levels
  • Uniform flow and temperature profile - ideal for spray drying applications
  • 3D plant layout modelling


Key Features

  • Stainless steel internal materials
  • Digital combustion control
  • Separate combustion and heat exchange zones with FGR


Optional Items

  • Flue Gas Recuperator (economiser) for energy recovery
  • Static flow mixer to ensure temperature uniformity in short outlet ducts
  • Multiple air stream outlet temperatures
  • Dual fuel oil/gas burner options