Process-based Carbon Emission Estimation Method And Life Cycle Environment Assessment Of The Petroleum Refining Industry

Global climate change and ecological environment pollution have been common global focus.As the largest CO2 emitter,China is facing the great pressure of carbon emission target made in global international community and serious environment protection situation.The petroleum refining industry is not only important for country economic development and energy supply but also the energy-intensive and high pollution industry.The petroleum refining industry has been the focus for Chinese government in the background of dealing with climate change and pollution reduction problems.The petrochemical industry was listed as the first pilot of national carbon charge market in 2017.With the increasingly strict requirement of petroleum products and stand of pollution emission,the pressure of saving energy and reducing emissions is further increased.In this situation,it is especially important to obtained the refined industrial carbon emission level and to understand the key point so as to make more efficient reduction way.This study conducted carbon estimation method and environment influence assessment from process level aiming to make up the gap of unsophisticated carbon estimation method,cannot obtained fugitive carbon emissions and cannot tract the crucial point of environment influence.The major content and results of this study as follows:(1)The accurate process carbon emission accounting system at the enterprise level has been established to make up for the inaccuracy of the current accounting results of the carbon emission system and the inability to calculate the carbon emission from unorganized sources.From the industrial structure,enterprise type,the angle of industrial processes and the emissions of four research scope is defined,the "production system-production equipment-production units-emissions node" four layer classification method for oil refining process carbon source for the identification and classification,the establishment of a material balance-the measurement method of enterprise level precision process carbon accounting methods,and medium-sized refineries in China as a case for the application.Carbon emission sources of various industrial processes are classified as fuel combustion sources,process exhaust sources,emission sources,waste treatment sources,and power and heat sources.The accuracy of the accounting method is reflected in:the carbon emission accounting of oil and gas recovery source,emission source and waste treatment source is increased,and the carbon emission accounting of non-CO2 form is increased.The carbon emission coefficient of electricity takes into account the influence of clean electricity,and the accounting method of fuel combustion source and production process's unorganized VOCs emission is more accurate.The calculation results of the case application are as follows:the carbon emission coefficient of this medium-sized oil refining enterprise is calculated as 0.3 0t C02eq/t crude oil;catalytic cracking,continuous reforming,atmospheric and pressure reduction,oil storage and diesel hydrogenation are the main processes of the whole plant;carbon emission from emission source accounts for 6.84%of the total carbon emission of the whole plant;non-CO2 emissions account for 13.76%of total carbon emissions.The results of comparative analysis of different accounting methods are as follows:the accounting results of petrochemical guidelines,provincial guidelines and 2006IPCC guidelines are 11.11%,55.27%and 80.93%lower than those of this method,respectively.The VOCs emission coefficient of the production unit without organization source calculated by the method of troubleshooting guidelines is 31.82%of the calculation method in this paper.The calculation result of the catalyst burning source by the measured method is only 7.3%of the calculation result of this method.(2)An accounting method for carbon emissions from petroleum refining at the industry level from an industrial process perspective is proposed innovativly,which can make up for the limitation of the application scope of the existing accounting results based on the emission category.This paper makes a qualitative and quantitative analysis of the carbon emission characteristics and influencing factors in the oil refining industry from 2000 to 2017,reveals the existing problems in the industry's carbon emission reduction,and identifies the industry's carbon emission reduction priorities.This paper builds the carbon emissions accounting method of industry level respectively from the point of view of industrial process and discharge type to,accounts5 the carbon emissions of oil refining industry in 2000-2017 based on the method of emission category,qualitative analysis the industry carbon emission characteristics from the carbon emissions,carbon intensity,coefficient of carbon emissions three points,quantify the contribution to the carbon increment of processing scale,energy efficiency,energy structure,the discharge coefficient using LMDI model.From 2000 to 2017,the carbon emissions of the oil refining industry increased year by year and have not yet reached an inflection point.From 2000 to 2017,the carbon emission coefficient of the industry shows the feature of"suppressing before increasing".The large-scale and clustered development has positive effects on carbon emission reduction.The extension of the industrial chain is the reason that the carbon emission coefficient of the industry "rises".To meet the country's commitment to reduce carbon intensity by 60-65%from 2005 levels,the oil refining industry needs to further increase the added value of its products and promote carbon emission reduction.The promoting effect of processing scale on carbon increment decreases year by year,but it is still the leading factor leading to carbon increment of the industry.Energy efficiency has become the second largest factor to promote carbon emissions after the processing scale,and has begun to play a role in promoting carbon emissions.Currently,the means to improve energy efficiency has gradually failed to meet the development needs of the industry,so it is urgent to find more effective ways to improve energy efficiency.The contribution of energy structure to carbon increment is relatively small,and the energy structure factor to the carbon emission reduction potential needs to be further tapped.The contribution of carbon emission factors to annual carbon increment is not obvious enough,and the effect values are all negative.The carbon emission factor plays an inhibitory role on the carbon emission of petroleum refining industry,and the inhibitory effect is not obvious.(3)Life cycle assessment(LCA)method was used to quantify the environmental impact of typical petroleum refining enterprises from the level of industrial process.Source analysis of the shortcomings of key impact links.It made up for the shortcomings of carrying out life cycle environmental impact assessment based on specific petroleum products,which cannot fully reflect the current status of the overall environmental impact of petroleum refining,and cannot analyze the key impact links from the source.Based on the process environmental impact assessment method,a comprehensive and systematic quantitative assessment of the environmental impact at the industrial process level of medium-scale typical enterprise was carried out.It has cleared the main environment impact of petroleum refining process category,identified the main contribution to the devices and materials,analyzed the key elements of the main devices from the source,and from the angle of unit materials comprehensive environmental impact level of environmental impact evaluation of industrial process.The main environmental impacts produced by the petroleum refining process were ozone depletion,climate change,human toxicity,particulate matter formation,photochemical oxidant formation,water acidification,terrestrial ecotoxicity,freshwater ecotoxicity and eutrophication,which had more obvious impacts on human health.For the entire petroleum refining enterprise,the crude petroleum extraction and production process was the leading factor causing environmental impact;At the industrial process level,catalytic cracking,catalytic reforming,atmospheric and vacuum,diesel hydrogenation,oil storage,circulating cooling system were mainly processes that caused the environmental impact of petroleum refining;The on-site emissions of volatile organic compounds(VOCs),the combustion of refinery gas,the use of electricity and heat,the production and use of auxiliary agents,the cooling of circulating water,and the air-cooled water cooling process of oil were the four environmental impacts that cause the above devices.The key link is also the focus of future control of the petroleum refining industry;The main influencing factors that lead to the contribution of the above links included the nature of raw materials,production technology,oil storage type and management level.Excluding the influence of the processing amount of raw materials of each production device,the environmental impacts of diesel hydrogenation,catalytic cracking,catalytic reforming(including benzene extraction),MTBE,delayed coking,and atmospheric and vacuum were sequentially reduced.The use of hydrogen was the main reason for the distance between diesel hydrogenation and other devices.(4)It innovatively constructs a statistical framework of carbon emission data based on industrial process at the enterprise and industry level,and enriches and improves the statistical theory and method of carbon emission data in the petroleum refining industry.In view of the current situation of carbon emission data statistics based on the emission category of enterprises in the petroleum refining industry,a carbon emission data statistical framework corresponding to the above carbon emission accounting method of enterprises in the industrial process is constructed from the perspective of industrial process.According to the result of environmental impact assessment of the process life cycle,some suggestions are put forward for reducing the emission of VOCs and improving the energy utilization.In the form of carbon emission data statistics at the enterprise level,two types of internal carbon emission ledger and external statistical statements are designed.The carbon emission ledger records the most original data needed for the internal carbon emission accounting of the enterprise,including the two dimensions of the whole factory and each industrial process,so as to facilitate mutual verification and ensure the accuracy of the data.External statistical statements are in a unified format,which can be uniformly sent to enterprises by administrative departments.The statements are mainly used to provide data required for carbon emission accounting at the industry level,including a master table that reflects the overall carbon emission information of each industrial process and a sub-table that provides information of different carbon emission categories of each industrial process.The statistical framework of industrial process carbon emission data at the industry level takes the industrial process as the basic statistical unit,and further classifies each industrial process according to the raw material,process,technology and scale.The statistical content includes the information of carbon emission and carbon emission coefficient at the industry level of each industrial process under the sub-category.As for the emission reduction of VOCs in petroleum refining,Suggestions are provided on how to regulate the government from four aspects:on-line monitoring of installation,dual control of collection and removal efficiency,tightening of VOCs emission standard,and timely updating and improving the evaluation system of cleaner production.In aspect of energy utilization,three aspects put forward relevant countermeasures in terms of optimization device structure,improving energy efficiency,and expanding energy structure,including gradually reduce the proportion of catalytic cracking unit,to further improve the proportion of hydrogenation process in secondary processing,strengthen the transformation or elimination of small-scale device,further excavate the refining integration advantage of improving energy efficiency between devices and system,raise the proportion of clean electricity and natural gas,etc.