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Case

District energy

District heating

Waste-to-energy

Surplus heat from industry keeps citizens warm

19. October 2021
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Solution provider

Confederation of Danish Industry (DI)

The Confederation of Danish Industry (DI) is the voice of corporate Denmark. On behalf of 19,000 member companies, we work to ensure synergy between society’s goals concerning business competitiveness, a clean environment and energy security. Jointly, these goals create the foundation for green growth.

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Challenge

To produce cement, raw materials such as limestone and sand must be burned at temperatures of up to 1500°C. Due to this high temperature process, the Aalborg Portland cement factory generates enormous amounts of excess heat. One of the main sources of waste heat is the flue gas streams from the white kilns. 

Solution

The solution to this energy loss was to implement a heat recovery system, in which the flue gases from the five white kilns are utilised in heat exchanger installations to transfer the thermal energy from the flue gas to the City of Aalborg’s district heating network.  

Consequently, the Aalborg Portland cement factory now supplies surplus heat from production in the form of district heating to the residents of Aalborg.  

Results

In 2019, this surplus heat corresponded to the annual heat consumption of approximately 25,000 households. There are also other projects in the works to utilise excess heat, such as reusing the hot air from the grey kiln’s clinker cooler as primary inlet air to all the white kilns and one of Aalborg Portland’s coal mills.