A GEA Emission Control technology solution enables electricity and compressed air to be generated from otherwise unused waste heat from flat glass production lines.

Waste Heat Recovery Unit at Sriperumbudur (India) plant (Photo: GEA)
Waste Heat Recovery Unit at Sriperumbudur (India) plant (Photo: GEA)

Two plants for waste heat recovery in flat glass production lines of the Saint-Gobain Group at locations in India (Sriperumbudur) and Italy (Pisa) have now been commissioned. In Sriperumbudur, the plant is producing electricity, while in Pisa the production of compressed air and thermal energy for ambient heating are also important factors for the plant. However, both locations have one thing in common: with this GEA solution, Saint-Gobain can significantly improve energy efficiency in production and save resources. This is also shown by the characteristic data obtained to date.

In both plants, the waste heat is extracted from the flue gas in a heat exchanger and transported to an ORC (Organic Rankine Cycle) via a thermal oil circuit at high temperatures around 300°C and with high flexibility. From this in turn, electrical power is produced. In addition, a compressor is operated at the Pisa plant via the ORC turbine, which contributes to the plant's compressed air supply. In winter, additional flexibility was provided by the fact that the heated thermal oil could at the same time supply thermal energy to a hot water circuit for ambient heating.

Impressive performance

After several months of operation, the plants are showing the expected performance. In this way GEA not only contributes to the sustainability of glass production and the reduction of CO2 emissions but also to the reduction of operating costs. 

The important key data of both waste heat recovery plants are summarized in the table below:

Pisa plant (Italy) Sriperumbudur plant (India)
Recovered thermal power from waste heat flue gas ~ 4.500 kW ~ 6.100 kW
Possible uses Electric Power generation,
Compressed air generation,
Hot water for ambient heating
Electric Power generation
Gross electric generated power ~ 960kW ~ 1.200kW
Net electric generated power ~ 800kW ~ 1.000kW
Generated compressed air volume ~78 m³/min, i.N. dry not installed
Generated thermal power via hot water for ambient heating Up to ~ 4.500 kW
(winter operation)
not installed
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