Ethylene production by the thermal cracking of naphtha is an energy-intensive process （up to 40 GJ heat per tonne ethylene）, leading to significant formation of coke and nitrogen oxide （NOx）, along with 1,8- 2 kg ...Ethylene production by the thermal cracking of naphtha is an energy-intensive process （up to 40 GJ heat per tonne ethylene）, leading to significant formation of coke and nitrogen oxide （NOx）, along with 1,8- 2 kg of carbon dioxide （CO2） emission per kilogram of ethylene produced, We propose an alternative pro- cess for the redox oxy-cracking （ROC） of naphtha, In this two-step process, hydrogen （H2） from naphtha cracking is selectively comhusted by a redox catalyst with its lattice oxygen first, The redox catalyst is subsequently re-oxidized by air and releases heat, which is used to satisfy the heat requirement for the cracking reactions, This intensified process reduces parasitic energy consumption and CO2 and NOx emissions, Moreover, the formation of ethylene and propylene can he enhanced due to the selective com-bustion of H2, In this study, the ROC process is simulated with ASPEN Plus^R based on experimental data from recently developed redox catalysts, Compared with traditional naphtha cracking, the ROC process can provide up to 52% reduction in energy consumption and CO2 emissions, The upstream section of the process consumes approximately 67% less energy while producing 28% more ethylene and propylene for every kilogram of naphtha feedstock,展开更多
Predicting the best shutdown time of a steam ethylene cracking furnace in industrial practice remains a challenge due to the complex coking process. As well known, the shutdown time of a furnace is mainly determined b...Predicting the best shutdown time of a steam ethylene cracking furnace in industrial practice remains a challenge due to the complex coking process. As well known, the shutdown time of a furnace is mainly determined by coking condition of the transfer line exchangers （TLE） when naphtha or other heavy hydrocarbon feedstocks are cracked. In practice, it is difficult to measure the coke thickness in TLE through experimental method in the complex industrial situation. However, the outlet temperature of TLE （TLEOT） can indirectly characterize the coking situation in TLE since the coke accumulation in TLE has great influence on TLEOT. Thus, the TLEOT could be a critical factor in deciding when to shut down the furnace to decoke. To predict the TLEOT, a paramewic model was proposed in this work, based on theoretical analysis, mathematic reduction, and parameters estimation. The feasibility of the proposed model was further checked through industrial data and good agreements between model prediction and industrial data with maximum deviation 2% were observed.展开更多
Yanshan Petrochemical Company after having expanded its 300 kt/a steam cracking unit to 450 kt/a in 1994 is still experiencing such problems as low feedstock flexibility, high energy consumption and smaller scale of e...Yanshan Petrochemical Company after having expanded its 300 kt/a steam cracking unit to 450 kt/a in 1994 is still experiencing such problems as low feedstock flexibility, high energy consumption and smaller scale of ethylene unit.In order to fully improve technical capability of steam crackers, reduce energy consumption, improve feedstock flexibility and increase production capacity, a lot of technical revamp cases on steam cracking were studied and compared.Revamp of relevant facilities has expanded the ethylene capacity to the target of 660 kt/a with the actual capacity reaching 710 kt/a. This revamp project has remarkably reduced the energy consumption, which is capable of using naphtha, light diesel fuel, heavy diesel fuel and the hydrocracked tail oil as the steam cracking feedstock. This project is the first to apply refrigeration by means of a mixed cooling agent and has succeeded in using C, catalytic rectification/hydrogenation technology, which has given an impetus to the progress of steam cracking industry in the world.展开更多
基金This work was supported by the US National Science Foundation （CBET-1604605） and the Kenan Institute for Engineering, Technol-ogy and Science at North Carolina State University.
文摘Ethylene production by the thermal cracking of naphtha is an energy-intensive process （up to 40 GJ heat per tonne ethylene）, leading to significant formation of coke and nitrogen oxide （NOx）, along with 1,8- 2 kg of carbon dioxide （CO2） emission per kilogram of ethylene produced, We propose an alternative pro- cess for the redox oxy-cracking （ROC） of naphtha, In this two-step process, hydrogen （H2） from naphtha cracking is selectively comhusted by a redox catalyst with its lattice oxygen first, The redox catalyst is subsequently re-oxidized by air and releases heat, which is used to satisfy the heat requirement for the cracking reactions, This intensified process reduces parasitic energy consumption and CO2 and NOx emissions, Moreover, the formation of ethylene and propylene can he enhanced due to the selective com-bustion of H2, In this study, the ROC process is simulated with ASPEN Plus^R based on experimental data from recently developed redox catalysts, Compared with traditional naphtha cracking, the ROC process can provide up to 52% reduction in energy consumption and CO2 emissions, The upstream section of the process consumes approximately 67% less energy while producing 28% more ethylene and propylene for every kilogram of naphtha feedstock,
基金Supported by the Major State Basic Research Development Program of China (2012CB720500)the National Natural Science Foundation of China (U1162202, 21276078)+2 种基金the National Science Fund for Outstanding Young Scholars (61222303)the Shanghai Key Technologies R&D Program (12dz1125100)the Shanghai Leading Academic Discipline Project (B504)
文摘Predicting the best shutdown time of a steam ethylene cracking furnace in industrial practice remains a challenge due to the complex coking process. As well known, the shutdown time of a furnace is mainly determined by coking condition of the transfer line exchangers （TLE） when naphtha or other heavy hydrocarbon feedstocks are cracked. In practice, it is difficult to measure the coke thickness in TLE through experimental method in the complex industrial situation. However, the outlet temperature of TLE （TLEOT） can indirectly characterize the coking situation in TLE since the coke accumulation in TLE has great influence on TLEOT. Thus, the TLEOT could be a critical factor in deciding when to shut down the furnace to decoke. To predict the TLEOT, a paramewic model was proposed in this work, based on theoretical analysis, mathematic reduction, and parameters estimation. The feasibility of the proposed model was further checked through industrial data and good agreements between model prediction and industrial data with maximum deviation 2% were observed.
文摘Yanshan Petrochemical Company after having expanded its 300 kt/a steam cracking unit to 450 kt/a in 1994 is still experiencing such problems as low feedstock flexibility, high energy consumption and smaller scale of ethylene unit.In order to fully improve technical capability of steam crackers, reduce energy consumption, improve feedstock flexibility and increase production capacity, a lot of technical revamp cases on steam cracking were studied and compared.Revamp of relevant facilities has expanded the ethylene capacity to the target of 660 kt/a with the actual capacity reaching 710 kt/a. This revamp project has remarkably reduced the energy consumption, which is capable of using naphtha, light diesel fuel, heavy diesel fuel and the hydrocracked tail oil as the steam cracking feedstock. This project is the first to apply refrigeration by means of a mixed cooling agent and has succeeded in using C, catalytic rectification/hydrogenation technology, which has given an impetus to the progress of steam cracking industry in the world.
