The tests are part of the ELECTRA project, which is exploring new technologies to replace traditional combustion processes with electricity-based solutions in the long term. Plasma technology is one of these technologies.
A major advantage of electrifying cement production is that the resulting flue gas is almost pure carbon dioxide gas. This means that the carbon capture step in the CCS chain can be simplified, leading to:
- lower energy consumption
- lower carbon emissions and
- lower investment costs for the entire production chain, including geological storage of carbon dioxide, as the total amount of carbon dioxide is also reduced.
Fuel-related carbon dioxide emissions from cement production are eliminated because no fuel needs to be used in the production process.
Instead of fuel, carbon dioxide gas is heated to over 5,000 degrees, where it becomes a plasma jet that heats the material in the kiln.
This is backed up by a wealth of knowledge from laboratory tests, calculations, and simulations. The first results on the products from the plasma furnace show that the alite crystals are smaller than in conventional clinker, indicating that a more reactive cement can be obtained.
The main challenge now is to seal the furnace even better. The aim of the project is to have 99 % carbon dioxide gas in the kiln. Now it is only 60 %, which is due to leakage. So, the kiln has to be sealed and an overpressure created.
Carbon dioxide is the so-called carrier gas used in the furnace. The gas is heated to 5000 degrees by electricity, creating a plasma jet. The plasma itself is very hot, but the radiant heat is low. Instead, it is heated mainly by conduction and convection.
The carbon dioxide used in the furnace is then purified and returned to the plasma, where it is used again as a carrier gas. This is a closed cycle, where only the carbon dioxide extracted from the raw material is processed for geological storage.
Heidelberg Materials collaborates within the ELECTRA consortium, which is exploring new technologies to replace traditional combustion processes with electricity-based solutions in the long term. The project consists of 17 partners from 8 countries.
