Electrified calciner concept for CO2 capture in pyro-processing of a dry process cement plant

Abstract

Around two-thirds of the CO2 emission from the cement industry comes from calcite decomposition (CaCO3 → CaO + CO2), and most of this reaction happens in the calciner. So, it is possible to reduce the CO2 emission significantly by electrifying the calciner. This possibility is studied in this work through a process simulation model using Aspen Plus. The model is first calibrated with experimental results for a cement calciner heated by coal firing. The validated model is then electrified with three scenarios of gas recycling. Electrifying an existing calciner will require high gas recycling, while some alternative designs require no gas recycling. The results indicate that this method could reduce the CO2 emissions by as much as 78%. The total energy (including fans, calciner and kiln) required in the coal-fired calciner system is around 138 MW. The energy in the electrified system may vary between 154 MW for high gas recycling and 137 MW for no gas recycling. The net excess energy in the electrified calciner per captured CO2 unit varies between 0.6 MJ/kgCO2 for high gas recycling and -0.04 MJ/kgCO2 for no gas recycling.