Heat recovery technologies

Heat recovery is a process that involves using thermal energy that would normally be dissipated into the environment. For example, heat generated by compressors, welders, turbines, engines, pumps, furnaces, or sterilizers can be effectively recovered and reused. The recovered energy can be used to supply central heating, domestic hot water, ventilation systems, and other technological processes.

Heat can be recovered from many sources – here are some examples:

• waste heat from production processes – this is heat that has been used to a useful extent for the production process, while the remaining energy is released into the surroundings, e.g. firing furnaces, bread baking ovens, boilers, pasteurizers, sterilizers, etc,
• heat from ventilation – energy recovered from ventilation systems that can be reused for heating or cooling buildings,
• heat from cooled equipment – this is heat that normally must be dissipated through forced cooling, e.g. air compressors, electric drives, injection molding machines, exothermic reactions, etc.

Heat recovery brings numerous benefits that translate into energy savings, reduction of CO₂ emissions, improved energy efficiency, and increased energy security. Thanks to heat recovery, companies can significantly reduce their energy intake from external sources, which directly results in lower operating costs. Reducing fossil fuel consumption and using recovered energy also helps greatly reduce carbon dioxide emissions, which is crucial in the context of global environmental protection efforts. Improving energy efficiency enables companies to obtain white certificates and other forms of financial support.

Nevertheless, implementing heat recovery systems also involves certain challenges and limitations. The biggest of these are initial costs, which can be significant, especially for advanced technologies requiring substantial investment. Another challenge is technical complexity related to the need to adapt and integrate heat recovery systems with existing processes. This may require advanced technical knowledge and specialized solutions. Additionally, some heat sources may be difficult to recover due to low-quality heat or its dispersion, which may limit the effectiveness of heat recovery technology under certain conditions.

Heat recovery systems work best in industrial plants that consume large amounts of thermal energy. Examples of industries where this technology brings the greatest benefits include chemical, food, metallurgical, and paper industries. In the food industry, heat from ovens or cooking equipment can be used to heat water or buildings. In the metallurgical industry, heat from smelting furnaces can be recovered and used in other production stages – similarly in the paper industry, heat from paper dryers.

An interesting solution we developed for a client from the chemical industry involved recovering heat from several processes and then using it to cover 50% of the demand for steam, which could be replaced by hot water in the media heating area. Heat recovery included cooling of vapors from the dryer, air compressors, chemical reactors, and ammonia towers. The effect was achieved within the first months after our audit.

• Cost: approx. PLN 6.7 million
• Savings: approx. PLN 3.4 million
• Payback period: approx. 2 years
• Emission reduction: approx. 2,300 tons of CO₂ annually
• Amount of energy saved: approx. 7,600 MWh annually

In a company from the automotive industry manufacturing components for passenger cars, we conducted an energy audit during which we identified 19 measures that could cost-effectively improve the plant’s energy efficiency. One of the solutions analyzed was the use of waste heat from cooling cast iron elements after casting, which need to be cooled down to ambient temperature.

Until now, the castings were cooled naturally. To assess the potential of wasted heat, our engineers performed a test which showed that one rack of castings can boil 1 m³ of water within 40 minutes! By using this heat to power an absorption chiller, the production of chilled water used in the technological process becomes more efficient and consumes less electrical energy.

The annual thermal energy savings amount to over 7,600 MWh, which corresponds to the annual energy consumption of more than 4,200 Polish households. Until now, cooling was produced using electrical energy, and thanks to this investment, that energy will no longer be drawn from the National Power System. This means that it will not need to be generated, which in turn eliminates greenhouse gases emitted by coal-fired power plants during electricity generation – the carbon dioxide reduction in this case is about 2,300 tons of CO₂ annually.

Heat recovery from industrial processes is not only a way to achieve significant energy savings but also to improve operational efficiency and reduce environmental impact. By applying advanced technologies of recuperation, recirculation, and regeneration, companies can effectively reduce energy consumption, lower CO₂ emissions, and improve energy security. Although implementing heat recovery systems may involve high initial costs, the benefits of their application are invaluable. It is worth investing in heat recovery to increase the energy efficiency of your company and contribute to environmental protection.