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Machine Heat Recovery System - the igus heating concept with waste heat
Since 2021, we have been using 100% green electricity at our production site in Cologne. We have replaced old injection moulding machines with new ones that are 40% more energy efficient. This has enabled us to reduce our electricity consumption by 11% in relation to the increase in production hours. We use gas for heating in our production and office buildings and we switched to climate-neutral gas in 2021. However, we were concerned that we were using resources for heating even when the injection moulding machines generate enough heat. As of 2023, we have around 800 of these machines, spread across several buildings. So how do we manage to utilise this waste heat? A team of igus engineers asked themselves this question and began testing and trialling.
The result: Our Machine Heat Recovery System (MHRS) as a concept for a heating system that utilises the waste heat from the machines and does not require gas.
Our plan: We want to heat our buildings at the Cologne site without gas in the future and MHRS supports us in this endeavour. We also want to make the concept freely available to engineers, machine constructors and the industry.
Schematic representation of the heating concept
The idea behind the heating concept
During the injection moulding process, the hydraulic motors of the injection moulding machines become hot. To prevent them from overheating, the motors are cooled with water. The cooling water is provided by cooling towers, from which the 18-24 degree cold water is pumped to the machines. There, the cooling water absorbs the waste heat from the motor, is heated to around 35-45 degrees and fed to the fan heater. A fan on the heater heats the sucked-in air to approx. 30 degrees and thus heats the hall. At the same time, the heated cooling water cools down during this process and is pumped back to the cooling tower, where the process starts all over again.
The system is variably customisable and allows constant temperatures to be maintained even in certain production areas. It does not utilise the diversions via a heat exchanger, which would lead to temperature losses. Additional heating of the water using compressors is also not necessary. As heat is extracted from the hot water as it passes through the fan heater, the cooling requirement of the cooling tower is also reduced, which in turn saves energy.
The prerequisite for our MHRS concept is a closed cooling water system that is heated at one point by a specific process. It works particularly efficiently in areas where the hot water does not have to be transported far, as hardly any heat is lost. To increase efficiency even further, the pipes should always be insulated.
Detailed view of the control unit
The control unit in detail
The device developed by our engineers ensures that a fan heater within the production hall is supplied with maximum heat energy and at the same time prevents machines from being damaged by excessively high temperatures in the return flow. The heated cooling water from the machines enters the device via the inlet on the right-hand side of the device. Water flows via the electrically adjustable ball valve to a flow meter that measures the temperature. The temperature of the cooling water in this area must be at least equal to the desired room temperature so that the water can continue to be channelled to the fan heater via the dirt trap and the manual ball valve. Otherwise, the electric ball valve blocks the passage and opens the bypass via the electric ball valve.
The water cools down as it passes through the fan heater. This temperature is recorded by the temperature sensor. The heating power of the fan can be calculated from the temperature difference and the flow rate, which is shown on the display. As there is hot water inside the pipes, the device can be locked to prevent burns. As there is always dirt in the return pipes, a dirt trap is used to filter coarse particles. The ball valve can be turned over manually so that it can be replaced from time to time. This prevents all the water from the fan heater from flowing back down and flooding the appliance.
What's next for the MHRS heating concept?
Sometimes things move quickly from idea to realisation, as was the case with our "hall heating project". You test and try things out and suddenly you have a breakthrough and your colleagues can work in T-shirts even though the gas has been turned off. We will prepare our concept so that we can make it available free of charge. If you would like to find out when and how you can benefit from our waste heat concept, subscribe to our newsletter or visit this page regularly.
More about igus
Open & flexible - the igus factory
Our heating system is not the only thing that is special. Our building structure itself is too. The architecture of our headquarters in Cologne follows the guiding principle that our customers are at the centre of everything we do. From a distance, you can see the sun-yellow pylons towering into the sky, supporting the old and new factory buildings. They have no walls and can be flexibly remodelled and extended.