Process modelling and exergy analysis of CO2 power plant with recompression sequence

This research focused on modelling process and thermal efficiency analysis by using exergy analysis, for Brayton Recompression Cycle with supercritical carbon dioxide (CO2) as the working fluid for the generation of electrical energy. Recently, the recompression sequence was developed into a supercritical CO2 pilot power plant with a capacity of 252 kW by Sandia National Laboratories. Software of Aspen HYSYS is used for the modelling process and the efficiency identification method was carried out by the exergy analysis of the cycle from the data of pilot plant developed by Sandia National Laboratories. Exergy analysis is used for identifying location the occurs of heat loss (exergy destruction). Based on the pilot plant data, we design larger capacity supercritical CO2 power plant with a capacity of 10 MW and analyses the economic feasibility based on capital expenditure (CAPEX) and operational expenditure (OPEX). The modelling results are validated and have an offset of 5% from the actual data. The results of the exergy analysis show that the largest heat loss occurs in the HTR (High Temperature Recuperator) device, which is 62.9 kW or 15.2% of the available exergy. The overall exergy efficiency of the cycle is 237.1 kW or 57.3% of the available exergy. From the economic feasibility study, it shows the value of 37 million USD for CAPEX and 3.7 million USD for OPEX per year.