Environmental Impact Analysis Of Ethylene Production Based On Life Cycle Method

As one of the important pillar products of China’s petrochemical industry,ethylene is particularly valued by various industries around the country.The "14th Five-Year Plan" proposed that the steady promotion of ethylene feedstock diversification is an important measure for the petroleum and chemical industry to achieve green and sustainable development.While the chemical industry brings economic effects,it also leads to massive consumption of resources and energy,and the idea of "Both gold mountains and the green environment" permeates all walks of society,causing widespread concern over environmental issues.Combined with the background of shale gas revolution in North America,the optimisation and updating of the raw material structure of the global ethylene industry has brought new opportunities to enhance the competitiveness of ethylene feedstock.The light-feedstock development of ethylene raw materials replaced traditional high energy-consuming source paths such as oil and coal,which followed the policy guidelines of the 2030 Carbon Emission Reduction Peak Policy.However,the environmental impact of newly commissioned alkane cracking to ethylene projects is not clear.Therefore,this study used the life cycle method to analyze the environmental impact of the change in process feedstock for the olefin pathway in China,with the aim of providing a theoretical basis for the green and sustainable development of the petrochemical industry in China.The conclusions of this thesis are as follows:(1)Based on life cycle thinking and environmental theories of sustainable development,this study compared the environmental impacts of ethylene production from different domestic feedstock sources(crude oil-based naphtha,coal-based methanol,natural gas-based ethane,bio-based ethanol).It was found that raw material mining stage had the main environmental contribution(account for 46 %,90 %,43 %,and 88 %,respectively).The choice of different feedstock processing methods therefore directly affect the environmental load of ethylene production.In terms of cumulative energy indicators,the overall environmental impact of the natural gas-based pathway is the most friendly(2.12E+04 MJ),followed by the petroleum-based(1.55E+05 MJ)and the coal-based pathway causes the most significant environmental impact(2.17E+05 MJ)is approximately 10 times greater than that of the natural gas-based.Although the biomass pathway also presents better environmental effects,its development in China is limited by feedstock and economic costs,while the ethane source is promising,so the choice of the emerging ethane cracking pathway is in line with the green petrochemical development objective of feedstock lightening.(2)Further analysis of the domestic ethane cracking process(including transport stage)showed that: natural gas extraction still had a significant impact on various indicators.But among the AP indicators,the ethane transportation stage of the model caused 66.23% of the environmental load,which indicating that the selection of transportation fuel has great optimization space in the future.Comparing the three typical ethane to ethylene cracking processes from the CML cumulative standardised results showed that the ethane dehydrogenation process has the highest environmental impact(7.82E-09),which is 1.27 and1.42 times higher than that of the Sinopec process(5.49E-09)and the CNPC process(6.13E-09),respectively.The results confirmed that the domestic dehydrogenation process need to be improved,while the natural gas-based ethane cracking to ethylene process has clear advantages and is in line with the green environmental trend in China.