Air preheater maxxtec

Air preheater are heat exchanger to preheat or air heating of the combustion air by means of flue gas, steam, water or thermal oil. Air preheaters are used when exhaust temperatures of combustion systems are particularly high. This extracts the hot exhaust valuable energy, which discharged otherwise unused into the atmosphere and warming means of this exhaust heat the combustion air of the combustion process.

In the classical use, air preheaters are connected behind high-pressure steam boilers or thermal oil boilers with a flue gas temperature up to 400 ° C. Their exhaust temperatures lend themselves to preheat the combustion air up to 300 ° C. In this way, an air preheater save up to 10% of fuel costs and thus enables payback periods of less than two years. Meanwhile, air preheater also be used in low temperature ranges in order to make the most efficient use of the fuels and counter the rising fuel prices.

Maxxtec air preheater can be retrofitted easily behind all boiler makes and sizes.



Air preheater are liquid and air heat exchanger or exhaust and air heat exchangers. They are designed and carried out individually depending on the application. Air preheater can be performed in counterflow, co-current flow, co-current flow-countercurrent or cross-countercurrent or cross-co-current flow. The design depends on the media and the temperature conditions. For small construction, finned tubes are suited to arrange in a small space much heating surface. Is in the exhaust gas or in the air containing dust or other particles, so that deposits are expected, preferably smooth tubes are used, which are less prone to deposits and will be clean easier.

In most cases, an air preheater is performed in several stages, that means, it consists of several individual heat exchangers connected in series on the air side.

At steam boiler plants, the first stage often is a water or condensate heat exchanger, a steam-operated low-pressure heat exchanger connects in the second stage. The third and fourth stages are usually steam driven heat exchanger with higher vapor pressures.

Between the individual heat exchanger stages are mostly installed intermediate channel pieces, so that the individual bundles can be cleaned.

In their mode of action, air heaters are identical to air preheaters. These air heaters are often used as a drying air preheater, whereby the cleaned fresh or recirculated air is heated. This preheating results to a fuel consumption during combustion.

Compared with air preheaters, air heaters are usually equipped with finned tubes, what results particular in the recirculating air or circulating air heating in a very compact and space-saving design.

We calculate, design and manufacture our air preheater / air heater according to EU pressure equipment directive, ASME, and other international regulations.


Technical data

Medium: air, flue gas, exhaust gases, thermal oil, water, water-glycol mixture, brine, refrigerants, other media with known substance data
Temperature: standard heat exchanger to 560 °C, through special materials also higher

Thermal power:

standard air preheater/ air heater up to 10 megawatts (MW), virtually unlimited by combining and special constructions


carbon steel, stainless steel or special materials

Heat insulation & surface treatment:

according to customer specifications


without the installation of the airmaxx4 automatic flue gas cleaner, should, according to the contamination, once or twice a year a maintenance carried out


Advantages of air preheaters

  • reducing the fuel costs by means of additional heating energy through efficient heat recovery
  • increasing the degree of efficiency up to 10%
  • short payback period
  • suitable for all waste heat boiler / flue gas boiler / boiler types
  • suitable for all standard fuels
  • easy retrofit into existing systems


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