Design of electrified fluidized bed calciner for direct capture of CO2 from cement raw meal

Abstract

Using green electricity to calcine the raw materials and combining this with storage of the pure CO2 generated in the calcination process can significantly reduce CO2 emissions in the cement industry, which generates around 7 % of the global CO2 emissions.In this study, a lab-scale electrically heated fluidized bed calciner, operating with a mixture of fine meal particles and coarse inert particles, is simulated using CPFD software. The electrification of the reactor is done using several horizontal cylinders, which are electrically heated to provide energy both for heating the raw meal (with 77% CaCO3) up to the calcination temperature and for calcination (CaCO3  CaO + CO2). The reactor design is done based on a specified electrical energy input, the gas velocity required for fluidization of coarse inert particles and the velocity required for entrainment of the fine calcined particles. A fluidization velocity of 0.3 m/s appears to be optimal for the reactor, whereas 0.8 m/s resulted in complete entrainment of the bed. The maximum calcination degree achieved was 90% when operating with preheated meal. The average meal residence time was found to be 24-26 s.