On the way to achieving the goal of climate-neutral production by 2025, three engineers from Igus set to work on making the use of fossil fuels superfluous during production. To this end, they initially experimented with heat exchangers from a car and fans from a computer. The experiments became larger and more and more square meters could be heated. After six months, the new concept called 'Machine Heat Recovery System' (MHRS for short) succeeded in heating one of the large production halls at the factory in Cologne-Lind using waste heat from the injection molding machines. Depending on the heating requirement, the MHRS directs the hot water flows from the cooling circuit directly to the fan heaters and at the same time ensures that the machines do not overheat. As heat is extracted from the hot water as it passes through the fan heater, the cooling requirement of the cooling tower is reduced. This has the advantage that the previous gas heating is no longer required and less electrical energy is used for cooling. The fluctuating cooling circuit temperatures can be variably adjusted by the system. The MHRS does not take the familiar route via an expensive heat pump or a detour via a heat exchanger, as this would lead to temperature losses. An additional feed-in of waste heat from compressed air compressors is also not necessary. igus is already gradually reducing compressed air energy in order to cut energy costs. "With this in-house heating system, we will be able to reduce gas consumption to almost zero in future. We also need less electrical energy for cooling," says igus Managing Director Frank Blase. "We are therefore not only saving costs, but also reducing CO2 emissions and thus protecting the environment."

How the gas-saving heating system works

The hydraulic motors of injection molding machines heat up during operation. Just like in a car, they therefore need cooling to protect them from overheating. Cooling towers are used here, which provide cold water and feed it to the machines via a pipe system. The heated water returns to the cooling tower. When it is cooled again, the heat escapes into the atmosphere and is lost as energy. With the MHRS, some of the heat from the cooling circuit is tapped via a flow control system and fed directly to the heaters, which are located next to the old gas fan heaters. To prevent these heaters from clogging up immediately, dirt traps filter out suspended particles in the water. The warm water enters the new fan heater and sends the old fan heater into retirement. A fan on the fan heater then distributes the heated air throughout the hall. Only then does the water flow back to the cooling tower and the cycle begins again. As no heat exchangers are used, the system can also be operated in the low temperature range.

"We ourselves are convinced by our concept and are planning to rely entirely on machine heat as heating in production and in the offices in the future," says Dennis Berninger, factory manager at Igus and the driving force behind this project. The next plan is to equip the 7,209 m2 logistics center with nine fan heaters. Here alone, around 31.5 tons of CO2 can be saved annually. An important step for Igus towards its goal of being CO2-neutral with buildings and production by 2025.

Spurred on by this success, igus has decided to make the technology available to other industrial companies. According to a calculation drawn up by igus, over one million tons of CO2 and over 548 million cubic meters of gas could be saved if all injection molders worldwide were to use the technology. This corresponds to the annual gas consumption of 238,434 German four-person households. "We see huge potential for the MHRS in the industry, which is why we want to make the concept available to other companies free of charge. During our research, we didn't find any published, precise instructions ourselves," says Dennis Berninger. "Our website already provides information on how MHRS and the developed control unit work. More and more details are being added."