A novel post-combustion CO2 capture design integrated with an Organic Rankine Cycle (ORC)

Abstract

Fossil fuel-based power plants are the significant sources of CO2 emitted into the atmosphere that significantly affect global warming. While these power plants provide the robustness of the grids, even with the fast development of renewable electricity, utilization of CO2 Capture and Storage (CCS) technologies is one of the best solutions to reduce their emissions and environmental risks. However, one of the most significant drawbacks of these technologies is their highest costs related to their energy consumption as well as the specific requirements of the solvents, which prevalently impact their adaptation. Among these technologies, Post-Combustion CO2 Capture (PCC) processes are widely used in the case of the power plant. This research develops an onshore Aqueous Post-Combustion CO2 Capture (APCC) process with water as a physical solvent to achieve a high CO 2 capture ratio with low energy consumption. The flue gas stream from a power plant flows into APCC, which can capture 72 kton/year of CO2. About 97.4% of CO2 was captured in the process with a 49.5% electricity production to consumption ratio (22.74 MWh/ton CO2) The captured CO2 is then delivered into a CO2 injection well to be used for Enhanced Oil Recovery (EOR) purpose with 15Mpa, 30 °C, and 80 mol% purity. Two scenarios were considered to decrease the external power requirements (1) the electricity production to consumption ratio is increased to 58.2% by adding a Hydro-Pump to the process; (2) coupling an Organic Rankine Cycle (ORC) with R125 working fluid to the process and using sensitivity analysis to gain the best thermodynamic conditions to increase the power production to consumption ratio to 80%. By considering both scenarios, the parasitic power is decreased by 52.78–28.44% and the net power production from the NGCC power plant is increased to 18.604 MW. Finally, Pinch Design Method (PDM) is used to reduce the Operating Cost of the process by the best utility selection from 2.48 M$/year to 0.945 M$/year, and the best Heat Exchanger Network (HEN) design in terms of the lowest Capital Cost at 4.71 M$/year was designed.