Kinetics and Design Parameter Determination for a Calciner Reactor in Unique Conditions of a Novel Greenhouse Calcium Looping Process

摘要

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 degrees C and CO2 partial pressures of 400 to 1600 ppm (0.04-0.16%). The GCL process can provide the required heat and CO2 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 x 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%.