Reduce energy consumption of heating and cooling supply systems

Rising gas prices – Making use of waste heat in industry

Food Pinch Einsparpotenziale für Wärme- und Kälteversorgungsanlagen

Typical industrial processes generate waste heat at a sufficiently high temperature level to enable further use. In the Food Pinch research and development project, we are developing innovative processes to significantly reduce the energy consumption of heating and cooling supply systems in industrial plants and thereby leverage potential savings. This increases competitiveness and at the same time protects the climate.

Increasing energy efficiency while reducing dependence on imports

Germany is experiencing an energy shortage, with gas prices at a record high. Progressing climate change and the war in Ukraine make it clear: We must become more independent of energy imports and at the same time exploit energy efficiency potentials.

Due to higher prices, German gas storage facilities were already insufficiently filled last summer. The result is that gas suppliers are now only buying what is absolutely necessary. And at high costs. These high prices may mean that companies have to reduce their production volumes in order to protect their economic viability.

But every crisis also holds potential. In industry, engineers are now called upon to design processes more efficiently, save energy or find alternatives. Our ÖKOTEC expert and Food Pinch project manager, Knut Grabowski, is particularly concerned about energy efficiency, even without rising prices. After all, it is best if energy is not even consumed in the first place. And so, back in 2016, he developed the idea of leveraging energy-saving potentials in the food industry by further developing pinch analysis with the targeted use of waste heat and additional cold.

In this article, we use cooling as a counterpart to waste heat. Cooling comes into the plant through outdoor air flows in winter and cold water flows. 

Optimal use of existing energy flows in the production process

Typical food industry processes such as cooking, pasteurizing, baking, cooling and freezing generate waste heat at a sufficiently high temperature level for further use. Cold comes into the plant through outdoor air flows in winter and chilled water flows. However, due to the constantly changing temperature levels, a fixed linkage of the individual processes is not expedient. Instead, it is necessary to constantly check at which point in the process waste heat and cooling energy are generated and at what temperature. At the same time, it must be determined where these energy flows can be used most sensibly in the production process. And this is what ÖKOTEC experts and researchers from the Chair of Technical Thermodynamics (LTT) at RWTH Aachen University have been researching in the Food Pinch project since the beginning of March 2021 under the leadership of Knut Grabowski.

Intelligent monitoring and management with EnEffCo® software

However, these permanent calculations and the control of the heat flows cannot be done manually. Therefore, the intelligent EnEffCo® software developed by ÖKOTEC is used and further refined by the application partners of Food Pinch, Nestlé Wagner, Nestlé Maggi and Stockmeyer. The Westfälische Fleischwarenfabrik Stockmeyer is already a long-standing user of the EnEffCo® software to control energy consumption in production and to make achieved conservation visible. With the participation in Food Pinch you go one step further with us. Via the dynamic pinch analysis, the thermal networking of the processes is adapted to changing heat requirements and temperature levels at any time. The costs for heat and cold supply can thus be minimized at any time. Only in this way discontinuous heat flows can be accommodated.

Monitoring of waste heat systems as a basis for more energy efficiency

An important basis for this is the monitoring of complex waste heat systems. We have already been able to test this successfully in initial projects, as the following example shows:

Nutzung der Abwärme von Druckluftstationen und Lüftungsanlagen
The example shows the use of waste heat from various compressed air stations and a cooling supply for the heat supply of ventilation systems.
© ÖKOTEC Energy Management GmbH

In a customer’s plant, waste heat from various compressed air stations and a refrigeration supply is used to supply heat to ventilation systems (see figure). Here, the amount of possible waste heat utilization depends, among other things, on the compressed air required at various pressure levels, the cooling capacity, the heat requirement and other influencing variables such as temperature levels.

High costs due to unnoticed control error

Using our monitoring system deployed in June, we were able to retroactively show that over €40,000 in heating costs could have been avoided in the first half of 2021 through a monitoring report. This is also shown by the following time course monitoring of the actual and target waste heat:

Monitoring der Ist- und Sollabwärme mit EnEffCo®
Monitoring with EnEffCo® of actual and target waste heat © ÖKOTEC Energiemanagement GmbH

The increased heating costs were incurred because the control setting of the heating water temperature was changed at the end of 2020. This change was only required for a specific situation and was then not reversed.

Until now, there were no targets set for such complex systems and thus no possibility to detect malfunctions on the one hand and to use dynamic control systems on the other hand.

Due to the current high gas prices and the goal of climate neutrality, heat and cold recovery in the food industry will become more and more important and thus, in our view, the need for the monitoring and control tools presented will also grow.

Food Pinch is a four-year research and development project funded by the German Federal Ministry of Economics and Technology. The project executing organization is PtJ.
Funding code: 03EN2031A

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Knut Grabowski Team Energieeffizienz-Controlling

Knut Grabowski

Head of EnEffCo® Research & Development

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