STUDY OF CARBONATION REACTIONS OF CA-MG OXIDES FOR HIGH-TEMPERATURE ENERGY-STORAGE AND HEAT TRANSFORMATION

Storing and temperature upgrading of heat energy at 773 K by means of a CaO-CO2 reaction seems very attractive. One way of storing the react ion product CO2 gas is in the form of an other carbonate by letting it react with a metal oxide, such as MgO or ZnO. Two metal oxides, MgO a nd (CaMg)O-2 were selected for CO2 storage, with the CaO-CO2 energy st orage system as CaO-CO2-MgO and CaO-CO2-CaMgO2 systems, and studies on CaO-CO2, MgO-CO2 and CaMgO2-CO2 reactions over the temperature range 773-1073 K were carried out. As the CaO-CO2 system is used not only fo r storing the heat energy but is also expected to perform as a heat tr ansformer, verification of the temperature upgrading ability is made b y means of a lab-scale adiabatic reactor, Pseudo-steady state temperat ure and pressure existed during the experiments, which correspond quit e well with Haul's equilibrium dissociation values of CaCO3, illustrat ing that upgraded temperatures of above 1273 K can be achieved by adju sting the carbonating CO2 gas pressure to around 500 kPa.