Recovering heat to cut costs

Heat recovery is possible from most compressors, usually from 15kW / 20hp to 315kW / 430hp. The recovery system is simple to install at very little cost. 

Distribution of heat

Electrical energy input to a compressor is converted into heat. This heat is then discharged with the aid of a cooling media – either water or air. The amount of waste heat that can be extracted from the compressor is approximately 94%. About 4% remains in the compressed air as residual heat and 2% is lost to atmosphere. The temperature of the hot air that can be recovered varies according to the type of cooling used.

Typically there are two ways to achieve heat recovery from rotary compressors: With air cooled compressors the hot air is channeled by a series of ducting into the workplace to be heated. A heat exchanger may be installed in the hot oil line in the compressor; water is then heated by this hot compressor oil. The other approach is the water cooled method where, again, the heat is recovered from the cooling water circuit or the heat is recovered from the compressor oil circuit

Air cooled compressors

Typicaly heat recovery applications include room heating; hot air is ducted away from the compressor and directed in to a room during autumn and winter. The air can be directed outside in spring and summer. 

Another application for heat recovery is for heating water. This is done by installing a plate and bar heat exchanger into the oil circuit of the compressor. This system is not complicated and initial investment is not expensive. Saving heat energy will amortise that cost within one year of operation.

Water cooled operation

With water cooled operation the recovered heat is taken from the cooling water circuit, where the warm water is piped to radiators around a building or, as with air cooled compressors, heat can be taken from the compressor oil circuit by means of a plate and bar heat exchanger.

Hertz Kompressoren use highly efficient heat exchangers; these are made from copper and have two pipes, one placed inside the other. Heated water will pass through the inner pipe. Between the two pipes there is a pressure sensor which does not allow any flow. If connected to an alarm it will send a signal in the event of any pressure failure.

Hertz Kompressoren offers a range of compressors where the heat recovery system is already built into the compressor cabinet for fixed speed or variable speed units. A retrofit system is also available with efficient, low cost plate and bar heat exchangers that can be fitted to other compressors

The system is not complicated and is easily installed to existing compressors or to new builds. With today's energy prices on the increase, this is an easy way to reclaim heat from your compressor at very little cost, while bringing down your annual heating costs.