Study On Overall Performance And Economy Of CO₂ Capture At Natural Gas Combined Cycle Power Plant

Carbon dioxide(CO2)is the most important greenhouse gas(GHG).The increase in GHG concentration in the atmosphere results in global climate change.CO2 emissions from the combustion of fossil fuels in the global power industry account for more than two-fifths of the total emissions.Optimizing power structure and improving energy efficiency are the main measures to reduce carbon dioxide emissions in power industry.Nuclear energy,hydropower,solar energy and wind power,as the low-carbon energy,are still in the initial stage of development in China,the power supply structure will still be dominated by coal-fired power and natural gas power and the proportion of natural gas power generation will increase year by year.In the longer term it is likely that new gas fired power plants will be required to be built and operated with CO2 capture and storage(CCS)technology to achieve deep reduction emissions.The main objective of this paper is to analyze the overall plant performance and CO2 capture costs of NGCC CO2 capture(NGCC-CC)power plant and provide technical reference for NGCC power plant intergrated with CO2 capture in future.(1)This paper analyzed the overall performance and the key indicators such as CO2 capture cost and energy consumption of 600MW NGCC power plants integrated with post combustion CO2 capture technology based on ethanolamine(MEA)using Integrated Environmental Control Model(IECM),sensitivity analysis was also made on the relevant factors affecting the CO2 capture cost and energy consumption.When integrated with CO2 capture system,the power plant efficiency loss is 6.92%,the net power output decreases from 584.8MW to 504.5MW,compared with the coal-fired power plant with similar capacity,the plant efficiency loss is about 4.00%because of CO2 capture.The Levelized Cost of Electricity(LCOE)at NGCC power plants will increase about 100 yuan/MWh integrated with CO2 capture.LCOE is mainly affected by the rate of CO2 capture,natural gas prices and plant capacity load.When natural gas prices increase by 10%,the LCOE of new NGCC plants without CO2 capture and post-combustion CO2 capture NGCC plants with MEA as absorbent will increase by 7.6%and 5.0%respectively.When the capacity factor drops by 10%,the LCOE will decrease by 1.6%and 2.0%respectively.(2)This paper simulated the 300MW NGCC power plant with/without CO2 capture under condensing,extraction and back-pressure conditions using Thermoflow's GT-Pro,GT-Master and Thermoflex simulation software respectively.After integrated with CO2 capture,the total power output and net power output under each condition will all decrease in varying degrees,and the net electricity efficiency will drop by 7-10 percentage points.The net electricity efficiency is the highest under condensing condition.and the smallest under back-pressure condition without CO2 capture,a difference of nearly 9 percentage points between the two conditions.By analyzing the exergy balance of the power plant with/without CO2 capture,it is found that the exergy efficiency of the NGCC power plant is less affected by the CO2 capture system.(3)This paper studied the trend of NGCC-CC cost in China based on Learning Curve Theory,established a learning curve model of NGCC-CC cost in China,and conducted a sensitivity analysis on the impact of model parameters on cost.The cost of NGCC-CC in China will be reduced to 50-250 yuan/ton CO2 by 2050 in the Wright,DeJong and D&L model,the cost of NGCC-CC in China is greatly affected by the progress of technology and the growth rate of NGCC-CC installed capacity.