Heat recovery system from screw compressors in the production of PVC profiles

For most enterprises, one of the main indicators affecting the cost of production is the cost of energy used in production. As in the rest of the world, the Ukrainian energy market is experiencing a steady increase in energy prices, so Dalgakiran Compressor Ukraine is actively offering its customers and partners comprehensive turnkey solutions using energy-saving technologies. One of these partners is Miroplast.

“Miroplast is the market leader in PVC profiles in Ukraine. The company is constantly increasing its production capacity and expanding its product range. The PVC profile systems produced allow us to create functional and aesthetic windows and doors for homes, offices, commercial and industrial premises, ensuring safety and excellent sound and heat insulation.

One of the main energy carriers used in the technological process of Miroplast profiles production is compressed air produced by screw compressors. To ensure the maximum energy efficiency of the DALGAKIRAN compressors used, our experts suggested implementing a system for recovering the heat energy released by the equipment during the air compression process and directing it to the consumer instead of discharging it into the environment, as was previously organized.

In the fall of 2021, Dalgakiran Compressor Ukraine specialists prepared and sent the Customer a technical and commercial proposal describing a technical solution, including a business case for the implementation of this project. After a joint risk assessment with Miroplast specialists, it was decided to organize a heat recovery system from the compressor equipment located on the territory of the Water Treatment Plant No. 2, namely DALGAKIRAN DVK-100 and DVK-75 screw compressors.

Technical solution

According to the project, the heat energy consumer is the lamination shop, whose technological process requires maintaining the indoor temperature at least 22 °C at any time of the year. Previously, this temperature regime was maintained with the help of gas rouffles. Natural gas consumption in winter averaged 800 m3/day.

The declared heat output obtained by the proposed heat recovery system is at least 110 kW.

The proposed heat recovery system consists of two hydraulic circuits:

• the primary circuit (recovery circuit), consisting of highly efficient recovery heat exchangers and pumping units of the required capacity for each of the compressors;
• Secondary circuit (heating system circuit of the lamination shop), consisting of main pipelines, circulation pumps and heating devices in the form of fan coils in the amount of 6 pcs. The fan coil units are controlled by controllers with built-in temperature sensors in the workshop room, with heaters connected in pairs, which ensures efficient and independent control of heat flows (one controller controls two fan coil units).

The interaction of these circuits with different flow and pressure characteristics is organized by a hydraulic mixer, which stabilizes the systems and efficiently distributes hydraulic flows. Water is used as a heat transfer medium.

As a result of this project, in December 2021, the Customer received 111.65 kWh of excess heat energy that was previously discharged into the atmosphere, with the following distribution of coolant temperatures:

• primary circuit (heating system circuit of the lamination shop):

_Supply temperature = 73 °С; _return temperature = 57 °С;

• secondary circuit (after the hydraulic mixer):

_Supply temperature = 67 °C; _return temperature = 55 °C.

In quantitative terms, the heat recovery unit allowed the Customer to reduce the use of existing gas rouffles to a minimum with natural gas consumption averaging 250 m3/day, which is more than 3 times lower than before the project.

The implementation of a turnkey project to recover heat energy from compressor equipment includes:

• Development of project documentation;
• Selection and supply of equipment;
• Construction and installation works;
• Performing commissioning and adjustment works.

Project manager: Denys Polishchuk.