Effect Of Ethylene Energy Efficiency Assessment And Operation Optimization On Energy Saving And Emission Reduction

The ethylene industry is the core of the petrochemical industry,and ethylene production is an also important indicator of the developmental level of national petrochemical industry.The demand for ethylene has been expanding with the continuous development of domestic economy,the production reached 17.81 million tons by the end of 2016.However,the energy consumption level of domestic ethylene industry is still higher than that of advanced countries in the world.At the same time,the impact of CO2,VOCs,SO2,NOx and particulate in ethylene production on environment and human health has become increasingly prominent,and the ethylene industry is one of the main source of these emissions.Development planning and policy of the national energy-saving emission-reduction required enterprises to implement energy-saving and emission-reduction.Moreover,there are many deficiencies existing in the domestic the ethylene evaluation system and operation optimization of energy consumption.Therefore,this paper chooses the energy efficiency evaluation and operation optimization of ethylene production is treated as the research topic,and carries out the targeted research according to the actual production and applies it to the actual ethylene production to achieve the dual goals of energy conservation and emission reduction of harmful substances.Ethylene production process is a complex system composed of multiple devices and processes.Each device interconnects and forms a process in the ethylene production and the multiple processes are connected together to form the entire system of ethylene production.Therefore,according to the characteristics of ethylene production process,the energy efficiency evaluation of ethylene production process should be divided in detail specifically,and analyzes the influencing factors of ethylene energy efficiency and conducts targeted energy efficiency assessment.In this paper,a three-level energy efficiency evaluation scheme is proposed based on equipment level,process level and system level.The three-level energy efficiency assessment covers the entire process of energy efficiency monitoring and evaluation of ethylene production.Through energy efficiency evaluation and operational optimization of equipment level and process level,energy efficiency evaluation of system level can be optimized.Three-level energy efficiency evaluation can better identify equipments and processes with higher energy consumption,and through real-time optimization and adjustment,the goal of energy-saving emission reduction ethylene is achieved in the production system.The energy efficiency evaluation methods of ethylene production are proposed in this study based on the three-level energy efficiency evaluation model and energy efficiency indices of ethylene production.In energy efficiency evaluation of equipment level,different energy efficiency evaluation indices for different equipment level are established,and a method of energy efficiency calculation and optimization adjustment is proposed based on thermodynamics law.For the process level,the energy baseline assessment of IOS 50001 standard is applied to evaluate the energy efficiency of the process.This energy baseline assessment is used for the cracked gas compression process,the results of energy baseline assessment proved this method is correct and feasible.At energy efficiency evaluation of system level,five system energy efficiency indices and evaluation calculation are put forward,and the energy efficiency improvement in the system level is achieved through energy efficiency evaluation and operation optimization in the equipment level and the process level.The energy efficiency assessment models,the indices and the energy efficiency evaluation methods are used to solve the energy efficiency evaluation problemes in the actual ethylene cracker production.The heat exchanger and pump are selected as the equipment level,quench process is selected as the process level,ethylene crackingplant is selected as the system level.Through the energy efficiency evaluation and operation optimization of equipment level and process level,the energy efficiency indices of the system level are improved.In this study,the proposed methods are applied to the ethylene crackingplant,and achieved remarkable results.Through the comparison of energy efficiency assessment indices of system level in 2014 and 2016,the ethylene energy consumption in 2016 is decreased by 6.99%than that in 2014,energy efficiency is increased by 7.53%.After the production load is modified,the energy consumption of ethylene is reduced by 3.16%and the energy efficiency is increased by 3.26%in 2016,reached the intended target for the ethylene consumption of the ethylene crackingplant scheduled to decrease by 2%.Decreased of ethylene consumption of the ethylene crackingplant reduce the amount of fuel,water,electricity,steam and compressed air in the ethylene production,which reduces the amount of CO2,VOCs,SO2,NOx and particulates emitted to the environment.Emissions of unit ethylene of CO2,VOCs,SO2,NOx and particulate matter decreased by 6.04%,27.24%,25.86%,34.18%and 16.33%respectively.Through the three-level energy efficiency evaluation and operation optimization of ethylene production,not only the energy consumption of ethylene production is reduced but also the discharged pollutants to the environment are reduced correspondingly,which achieve the purpose of energy saving and emission reduction of ethylene production.This study can provide a feasible research method for the whole petrochemical industry to keep higher energy efficiency in real time,and a reference for energy saving and emission reduction in the whole petrochemical industry.