Steam Coil Air Pre-Heaters

Air Pre-heaters is used to heat air and pass it to the furnace, the preheated air facilitates the burning of poor grade of fuel. Thus, permitting a reduction in excess air that is improving the efficiency.

The purpose of air pre-heater is to recover the heat from boiler flue gas, which increases the thermal efficiency of the boiler by reducing the useful heat lost in the gas.

We also have facility of manufacturing steam coil air pre-heater with IBR approval.

Trust Well Engineers India_Steam Coil Air Pre-Heaters
Design Considerations for Air Pre-Heater:

  • Careful selection of “fins” for specific process conditions.
  • Use of highly proven correlations for heat transfer and pressure drop calculations.
  • Careful check for gas pressure drop with optimum heat transfer coefficient need to keep low pressure drop to satisfy system design.
  • Check for various part load - to confirm safe operating range. Keep tube metal temp. below dew point in all operating cases.
  • Ease of installation, operation and maintenance in available space.
  • Cast iron metallurgy for specific cases.
  • Robust design - check for wind, seismic load, operation, external piping.
  • No thermal stresses - free expansion provisions air and gas side.
  • Ease of operation.
  • Ease of maintenance.


  • Furnace oil fired boilers.
  • Carbon black plant waste heat recovery.
  • Oil fired thermic fluid heaters.
  • Oil fired metallurgical furnaces.
  • High sulfurous fuel fired boilers like: pet coke, industrial waste slurry, MSW etc.
  • H₂SO₄ making process.
  • SO₂ making process - like sugar industry, etc.
  • Oil fired engine-generator sets.
  • Biogas (containing H₂S) fired engine-generator sets.
  • Solid fuel fired boilers with sulphur at lower temperature end.
  • Oil fired thermic fluid heaters.
  • Oil fired furnaces - metallurgical industry.
  • Fired Heater in oil - refineries.
Design Considerations:

  • Maximum utilization of waste energy.
  • Design with minimum pressure drop on gas side to avoid addition of new ID fan.
  • Check for upset condition with respective min tube metal temp and acid dew point.
  • Optimum heat transfer coefficient.
  • Layout to suit available space.
  • Effective online tube cleaning systems to suit to site layout.

Design Features:

  • Proven performance.
  • Proven construction.
  • Rugged.
  • Ease of maintenance.
  • Flexibility in layout – can be constructed to suit layout.


  • Isolation dampers, control dampers, shutoff blades
  • Metallic expansion joints.
  • Explosion doors-dead weight, spring type.
  • Ease of operation.
  • Steam soot blowers - motor operated.
  • Gas inlet, outlet box.
  • Acid resistant refractory, chain anchors.
  • Foundation bolts.

Operation & Maintenance:

  • Correct installation to avoid thermal stresses.
  • Soot cleaning by using soot blower regularly with designed steam conditions.
  • Intact mineral wool cladding on casing and inlet / outlet ducting.
  • Regular checkups of acid resistant refractory.
  • Strict monitoring of outlet flue gas temperature.
  • Regular draining and cleaning of acid from bottom nozzles.

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