Shropshire-based Müller Dairy has made substantial savings in gas process heating costs by utilising Atlas Copco compressors incorporating energy recovery technology.

Compressed air plays an essential role in Müller Dairy’s large scale production operation, based at its Market Drayton manufacturing plant, where over 600,000 litres of raw milk are processed daily.

This is particularly true in the company’s yogurt and fruit process operations, where compressed air is used in supplying air cylinders, filling machine and process valves, as well as providing a sterile air barrier for end products.

Müller Dairy’s compressed air installation comprises a purpose built ZR315VSDFF oil-free compressor together with two fixed speed ZR200s. The heat recovery capability of the two water cooled ZR200s is utilised in the form of recovered hot water. Working in conjunction with ammonia compressors and the yogurt and fruit processes, this hot water is used to pre-heat yogurt bases, thus eliminating the need to generate steam and the running costs of two gas fired boilers that used to be incurred in the process.

The new compressors supplement the original Atlas Copco installation, which consists of four ZR3-58 machines. These older machines are maintained by Müller Dairy as standby compressors and are employed on a rotational basis when there is a high production demand for compressed air.

Compressed air users who, like Müller Dairy, integrate the flow of hot water into their plant processes are able to recover 90-95% of a compressor’s electrical energy input as hot water. This is achieved successfully with Atlas Copco’s ZR series of water cooled, oil-free, 55-750kW compressors, which have been certified by TÜV, the independent testing and accreditation organisation, as capable of recovering up to 100% of electrical input energy as hot water under specific design conditions.

Over 45% of industrial applications use hot water in their process operations. The highest degree of thermal efficiency is generally obtained when a compressor’s hot water outlet is connected to a continuous heating demand, such as a heating boiler’s return circuit.

With energy consumption representing over 80% of a compressor’s lifecycle cost, across a wide spectrum of manufacturing industries, energy savings in compressed air systems have a significant impact not only towards preserving the environment through the reduction of CO2 emissions but also on the end users’ bottom line. In the Atlas Copco ZR oil-free screw compressor range with energy recovery control, the energy savings potential equates annually to 200 to 2500 tonnes of CO2 or £35,000 to £480,000 of electricity, gas or heating oil.