Energy Consumption Analysis And Economic Benefit Evaluation Of CO₂Capture System Of NGCC Power Plant

CO2is one of the main causes of global climate change. The long-term energy structure in China is given priority to coal, which leads to huge CO2emissions. Therefore, China should develop Natural Gas Combined Cycle (NGCC) technology. Under the background of energy conservation and emissions reduction, developing NGCC-CO2capture technology is of great significance.In this article, through software simulation, the site industrial test, design and calculation, study the process system, operation parameters, energy consumption and economic performance of NGCC-CO2capture system. The main purpose is obtaining engineering data of NGCC-CO2capture system, in order to provide technical reference for large-scale CO2capture in the future. The main content and conclusions include:(1)Study the NGCC-CO2capture systemThrough SWOT analysis, identify that NGCC-CO2capture technology has good prospects in China. Combined with characteristics of flue gas, determine that chemical absorption is the most appropriate technology for NGCC plant. Now, amine (mainly MEA) or mixed amine leads the absorbent market, other modified absorbents are in the attempt stage of business applications.Design the CO2capture of single unit of Gaojing plant. Calculate that the height of absorption tower is18m, the diameter of absorption tower is3m, the height of regeneration tower is14m, and the diameter of regeneration tower is2m.(2)Simulate the NGCC-CO2capture systemModel the CO2capture system of single unit of Gaojing plant with ASPEN PLUS. Analyze the influence of absorbent concentration, lean liquid load, CO2capture rate, operating pressure and temperature of regeneration tower, rich fluid temperature of regeneration tower, lean fluid temperature of absorption tower and gas temperature of absorption tower on renewable energy and water consumption of the system. Determine the optimized process parameters, the energy consumption of Gaojing CO2capture system is4.2GJ/tCO2.(3)Industrial experiment study of NGCC-CO2capture systemConduct an industrial experiment on the CO2capture (1500t/y) demonstration unit. Analyze the influence of regeneration tower operating temperature, lean fluid circulation flow rate and flue gas temperature of absorber tower entrance on capture efficiency. It is concluded that the best regeneration temperature is111℃～114℃, the best absorbent circulation flow rate is6m3/h, the best flue gas temperature of absorber tower entrance is34℃～38℃. Combined with the simulation results and industrial test results, give a set of process parameters recommended value of NGCC-CO2capture system. Under the recommended process parameters, regeneration power consume is3.96～4.2GJ/tCO2, low pressure steam consumption is1.67～1.77t/tCO2, MEA consumption is2kg/tCO2, power consumption is100～110kwh/tCO2, cooling water consumption is70t/tCO2, demineralized water consumption is0.5t/tCO2.(4)Evaluate the effect of CO2capture process on NGCC plantThrough the evaluation of economic benefit, the capture cost of NGCC plant is602CNY/tCO2. Under the cost, in non-heating season, the generating efficiency is decreased by4.4%and13.2%respectively, and in heating season, the thermal efficiency is decreased by8.2%and24.7%respectively; in the same time, in non-heating season, the generating cost is increased by12.09%and39.91%respectively, and in heating season, the generating cost is increased by14.03%and42.13%. If we use MEA as absorbent, and the capture scale is90%, it will increase about0.22～0.24CNY per kilowatt-hour.