Process Simulation And Optimization And Economic Evaluation Of A 600MW O₂/CO₂ Power Plant

The great sum of CO₂ emission has become a hot topic, and CO₂ emission control from pulverized coal-fired power plant is a priority. Oxyfuel is the most competitive technology in current several CO₂ reduction technologies. Oxyfuel is based on the traditional power plant and with air separation unit (ASU) and CO₂ capture and compression unit (CCU). The net electrical efficiency is descended and cost of electricity is increased as a result of the cost of ASU & CCU and the power consumption of them. Therefore, modeling the oxyfuel system, optimization and economic evaluation of the oxyfuel system is necessary.In this paper, the system optimization and economic evaluation of oxyfuel are the main study. Model and analysis the whole process of a 600MW pulverized coal-fired power plants in O₂/CO₂ atmosphere by Aspen Plus software and optimize the oxyfuel system. The modeling includes ASU, CCU, combustion system and thermodynamics system. From the simulation results, the results is very close with the actual air separation manufacturers and power plant operating data, and the simulated results of flue gas treatment system can achieve large-scale CO₂ pipeline transport requirements.When the traditional power plant retrofited oxyfuel power plant, the net electrical efficiency of oxyfuel is 25.62%, which should be compared to 37.69% in the traditional plant. With heat integration from ASU and CCU process and other optimization can result in reduced energy and efficiency penalties, the net electrical efficiency becomes 28.73% and the when the oxygen purity is 98%, the power consumption of ASU and CCU is fewest.Using the optimized data and the annualized cost of the entire system as a reference evaluate the economics of oxyfuel, the results showed that the cost of electricity of oxyfuel is 46.3% more than reference plant. The cost of avoided CO₂ is 172$/t and cost of capture CO₂ is 129$/t. Considering the sale and tax of carbon, oxyfuel showed obvious advantage than traditional power plant. In addition, in the view of stability and economic performance from the system, the combination of wet and dry cycle is the best choice. To ensure the recovery of CO₂ over 90%, air leakage must be controlled within 5%; and 1% increase in leakage, the system cost of electricity increased about 0.5%.