Approximately 70% of all manufacturers use compressed air systems to power items such as tools, materials handling and spray painting equipment. Compressed air is one of the most expensive and inefficient users of energy within in a manufacturing plant, with less than 10% of the input energy actually being delivered as compressed air, the remainder is lost as heat energy.
It is crucial that the heat generated by compressors is removed from the unit to prevent excessive temperature rises which may cause the units to trip. The vast majority of medium pressure (6 Bar) compressors utilise air as the medium to exchange and remove heat. Specialist high pressure compressors utilise water cooling to achieve heat transfer. The energy captured by both mediums (air and liquid) is usually transferred directly to atmosphere and is otherwise lost. It is at this stage that the energy could instead be recovered for winter space heating or hot water pre-heating.
The hot air from compressors can be used in the following manner:
- Building Service: Room space heating
- Building Services: Water Heating
- Process: Product or production line heating
- Process: Product drying
- Boiler Treatment: Combustion air pre-treatment
- Boiler Treatment: Feedwater pre-heating
- Compressed Air Treatment: integral or regeneration dryers
The savings made on heat recovery can be significant: savings on a standard 100kW compressor could amount to a minimum of £2,500 per annum, rising to more than double than when recovering for process heating or drying.