Life Cycle Assessment Of Supercritical Carbon Diaxide Coal-fired Power Generation System

China has an abundant coal reserves,and in a relatively long period,the coal-fired power generation will maintain its predominant role.However,the burning of a large amount of coal in the power generation process has aggravated the environmental pollution problems.Therefore,how to improve the energy efficiency of coal-fired power plant and achieve efficient and clean utilization of coal has become a major concern for current researches.Provided with the advantages of high cycle efficiency,small sized system components and so on,supercritical carbon dioxide(S-CO2)power generation technology is able to replace the traditional water-steam Rankine cycle power generation technology and achieve higher power generation efficiency under the same temperature and pressure parameters.However,how this efficiency advantage is reflected in environmental impact and economic costs requires further study.In this paper,the life cycle assessment method is adopted to evaluate the environmental performance and economic performance of 1000MW S-CO2 coal-fired power plant and 1000MW ultra-supercritical(USC)coal-fired power plant.At the same time,environmental assessment indicators and economic evaluation indicators are introduced into the multi-objective optimization model,taking into account the factors of thermodynamic performance,environmental performance and economic performance,to optimize the design of 1000MW S-CO2 coal-fired power plant system and offer theoretical reference for S-CO2 coal-fired power plant in the practical engineering.In this paper,the life cycle assessment and calculation model is used to study the 1000MW S-CO2 coal-fired power plant and the 1000MW USC coal-fired power plant by collecting the energy resource consumption and pollutant discharge data of the two power generation systems in the construction,operation,and decommissioning stages,establishing the data list,and then calculating the cost of major components of two power plants,finally,followed by the calculation,comparison and analysis of the three environmental performance evaluation indicators,(namely,energy payback ratio,resource depletion index and environmental impact load)and the three economical evaluation indicators,(namely,net present value,payback period and cost of electricity)of the two coal-fired power plants.The assessment results prove that the 1000MW S-CO2 coal-fired power plant has smaller environmental impact,lower economic cost,and is more energy-saving and environmentally friendly.In this paper,a multi-objective optimization model is constructed by taking the power generation efficiency,environmental impact load and payback period of 1000MW S-CO2 coal-fired power plant as the objective function,turbine inlet temperature and inlet pressure as decision variables,then maximizing power generation efficiency and minimizing the environmental impact load and payback period with MATLAB neural network genetic algorithm.By changing the weight of the objective function,the optimization results under the corresponding conditions are calculated respectively.The results show that when the weights of the three objective functions are 1/3,the optimal turbine inlet temperature of S-CO2 coal-fired power plant is 622.082?,and the optimum turbine inlet pressure is 30MPa.