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.
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.
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.