Experimental investigation of CaCO3/CaO reaction pair in a fixed bed reactor for CSP application

Abstract

CaCO3/CaO thermochemical energy storage (TCES) system has been widely studied on laboratory scale for its potential in concentrated solar power (CSP) plants. However, there is still need for the large-scale experiments based on which a detailed analysis can be obtained to improve this system for real-time applications. In this study, we developed a packed bed reactor capable of operating at high temperature and pressure providing the carbonation and decarbonation reactions of CaCO3/CaO reaction pair. The heat storage process is studied with the aspect of different decarbonation temperatures and different sample sizes (amount of sample in grams) placed in the reactor. Furthermore, we compared the heat storage performance of pure and composite samples. The heat release process is performed by varying the concentration of CO2 and the sample size of the loaded material. The results showed that the heat storage rate and efficiency improve by increasing the temperature of the decarbonation, implying that this reaction must be carried out above 925 °C for better performance. The heat is released smoothly and at a good rate when the concentration of CO2 is high in the reactor. Also, carbonation reaction (heat release process) depicts that CaCO3/CaO TCES system has a great potential to be used as a heat pump and is capable of upgrading the temperature of the released heat from lower to higher value.