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Air Preheaters

Air preheaters for efficient processing

Air preheaters take energy from a process stream to heat incoming air to a system. This operation increases the inlet temperature of the air to the process thus improves the overall efficiency of the system. Air preheaters may be configured as gas to air or liquid to air, depending on the available process streams.

What you can expect from us

  • Multiple design options – We have a range of design options that can be harnessed to address the most challenging process requirements. Whether it is considerations of the overall layout, the differential expansion or stream cross-contamination, we have a suitable arrangement to meet the challenge.

  • Cost effective specification – We can use plain tube arrangements on either fluid to air or gas to air preheaters where the use of extended surfaces is not an appropriate economic approach.

  • Corrosion resistant – Where gas streams are being cooled in transfer of energy to the incoming air, there is a risk of corrosion if condensate forms. In that case, we recommend appropriate materials and advise on the best configuration to minimise that risk.


How air preheaters work

An air preheater takes energy from a process stream to heat incoming air to a system. The availability of a preheater heat source is specific to the individual process. Heat may be available from condensate streams in a steam generating process. In that case, a water to air preheater is required. Gases downstream of a combustion process may require further cooling after the main heat recovery has been accomplished. If so, a gas to air preheater is called for.

Liquid to air preheaters

For liquid to air preheaters, extended surfaces are used to enhance the heat transfer coefficient of the air. Fin and tube pitching depends on the potential for fouling of the surfaces. Tube materials are based on an understanding of the corrosion potential from the tube side fluid. As the liquid can readily be supplied in small bore pipework, the overall layout of equipment is generally not an issue.

Gas to air preheaters

For gas to air preheaters, we potentially have to examine more factors. Using products of combustion to preheat air is a common requirement. However, the quality and temperature of the gas stream may vary significantly.

We consider significant solids carry over in the gas stream when determining the pitch of tubes and use an appropriate fouling factor. In the extreme mechanical methods for solids removal may need to be studied.

Tube expansion on start-up needs to be taken into account as an integral part of the design and may dictate significant aspects of the equipment layout.

Bringing together the gas and air streams can also be a significant factor as large diameter ducting affects the available layout options.



Most of the applications are in the following industry sectors:


Air preheater using NEL fin technology, designed and manufactured by Sterling Thermal Technology

Air preheater using NEL fin technology

Air preheater, oil sections

Air preheater, oil sections


As a recognised manufacturer of air preheaters, we can help you to get the best equipment for your application.

If you feel you need another type of heat exchanger, visit our products and services page or contact us.

Customised heat exchangers

Over 100 years of design & manufacturing knowledge

Your partner for the entire lifecycle of your business

Sterling Thermal have worked with us to develop the arrangement of air preheater which best suits our revised process arrangements. We have discussed all parameters to come to the optimal solution.

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We customise our heat exchange solution to meet your requirements, so contact us today to discover the right equipment for you.

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