Kinetics and design parameter determination for a calciner reactor in unique conditions of a novel greenhouse calcium looping process

The greenhouse calcium looping process (GCL) is based on the cyclic carbonation/calcination reaction of limestone under mild operating conditions, for example, temperatures of 600 to 800 °C and CO 2 partial pressures of 400 to 1600 ppm (0.04-0.16%). The GCL process can provide the required heat and CO 2 enrichment to greenhouses with limestone particles instead of fossil fuels such as natural gas. In this research, the calcination reaction of the GCL process was studied in a thermogravimetric analyzer (TGA) to determine its kinetic parameters. The experimental results showed that the calcination reaction follows a zero order reaction with a pre-exponential factor of 6.9 × 10 6 min -1 and an activation energy of 103.6 kJ mol -1 . Various models were analyzed to find out the most appropriate model for predicting the calcination reaction in the GCL process, of which the function G(x) = 1 - (1 - x) 1/3 was found most appropriate through the least-squares linear fitting of experimental data. The derived kinetic parameters were used in Aspen Plus v7.3 to establish the minimum calciner volume considering an RPlug unit. To obtain a practical overview of the energy efficiency of the calcination reaction in the GCL process, an exergy analysis was conducted, which highlighted an overall exergetic process efficiency of 85%