Ethane steam cracking process in an industrial reactor was investigated.An one-demsional(1D)steady-state model was developed firstly by using an improved molecular reaction scheme and was then simulated in Aspen Plus....Ethane steam cracking process in an industrial reactor was investigated.An one-demsional(1D)steady-state model was developed firstly by using an improved molecular reaction scheme and was then simulated in Aspen Plus.A comparison of model results with industrial data and previously reported results showed that the model can predict the process kinetics more accurately.In addition,the validated model was used to study the effects of different process variables,including coil outlet temperature(COT),steam-to-ethane ratio and residence time on ethane conversion,ethylene selectivity,products yields,and coking rate.Finally,steady-state optimization was conducted to the operation of industrial reactor.The COT and steam-to-ethane ratio were taken as decision variables to maximize the annual operational profit.展开更多
Fresh ZSM-5 zeolite catalysts were pretreated at 460 ℃and 500 ℃with various cumulative amount of water feed(CAWF) in a fixed bed reactor. The catalytic process was carried out under the following conditions: a tempe...Fresh ZSM-5 zeolite catalysts were pretreated at 460 ℃and 500 ℃with various cumulative amount of water feed(CAWF) in a fixed bed reactor. The catalytic process was carried out under the following conditions: a temperature of 480 ℃; a methanol WHSV of 3 h-1; a methanol partial pressure of 30 k Pa; and a time on stream of 12 h, 24 h and 48 h, respectively. The BET parameters of catalysts and diffusion coefficients of toluene showed that there were two types of mesopores generated under different hydrothermal conditions. Mild temperature and moderate CAWF conditions led to external open mesopores which could be entered from the external surface of the zeolite, while a high temperature or a high CAWF condition resulted in the generation of macropores or internal isolated mesopores, which were occluded in the microporous matrix. The TGA results showed that catalyst with external open mesopores had good ability to resist coke accumulation and good performance on propylene selectivity, while the internal isolated mesopores did no contribute to the increased diffusivity of reactants and products.展开更多
Hydrogen management is important for refineries to improve their business efficiency.Various approaches such as pinch analysis and mathematical programming have been employed in the management of hydrogen system.Howev...Hydrogen management is important for refineries to improve their business efficiency.Various approaches such as pinch analysis and mathematical programming have been employed in the management of hydrogen system.However,it is not easy for site engineers to implement these techniques,due to the complicated procedures.At this point,it is necessary to develop a software that can implement the proposed methodologies automatically,which is really the goal of this work.The presented refinery hydrogen system optimization software(RHO)is a web based system.It is developed in the Java Web environment,where the subroutines of mathematical model developed in GAMS software can be easily called.RHO can generate graphics of both the hydrogen pinch diagram and the hydrogen distribution network.The purifiers as well as the physical distances between units are considered in the optimization model.In addition,there is a special module for the calculation of membrane separation,which is very important in the hydrogen network.The functions and the interfaces of the software are illustrated via practical cases.Case studies show the effectiveness of the RHO software.展开更多
Acidity plays a vital role in methane conversion by co-feeding method,which is one of the best strategies to improve the utilization and gentle the reaction conditions of methane.In this work,Zn,Ni,Mo,La,Ga,Fe and Co-...Acidity plays a vital role in methane conversion by co-feeding method,which is one of the best strategies to improve the utilization and gentle the reaction conditions of methane.In this work,Zn,Ni,Mo,La,Ga,Fe and Co-impregnated ZSM-5 zeolites have been prepared with the same substitutions to variate the acidities and tested in co-aromatization of methanol with methane.It is demonstrated that the new medium-strong acid sites formed by metal and strong acid sites are the key role to activate methane in co-reaction.Zn-modified ZSM-5 catalyst is preferred to exhibit the best methane conversion of 12%,whose aromatic selectivity increases from 27.2%to 52.2%compared with that of HZSM-5.Besides,the addition of methane further improves the production of high-valued aromatics compared with methanol to aromatics(MTA)reaction.展开更多
基金The financial support provided by the Project of National Natural Science Foundation of China(21822809&21978256)the Fundamental Research Funds for the Central Universitiesthe Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(Grant No.2018-K23)are gratefully acknowledged.
文摘Ethane steam cracking process in an industrial reactor was investigated.An one-demsional(1D)steady-state model was developed firstly by using an improved molecular reaction scheme and was then simulated in Aspen Plus.A comparison of model results with industrial data and previously reported results showed that the model can predict the process kinetics more accurately.In addition,the validated model was used to study the effects of different process variables,including coil outlet temperature(COT),steam-to-ethane ratio and residence time on ethane conversion,ethylene selectivity,products yields,and coking rate.Finally,steady-state optimization was conducted to the operation of industrial reactor.The COT and steam-to-ethane ratio were taken as decision variables to maximize the annual operational profit.
基金supported by the National Natural Science Foundation of China(Grant 21176208&61590925)the National High-Tech R&D Program of China(Grant 2012AA030304)+1 种基金the International S&T Cooperation Projects of China(2015DFA40660)the Fundamental Research Funds for the Central Universities(Grant2015QNA4033)
文摘Fresh ZSM-5 zeolite catalysts were pretreated at 460 ℃and 500 ℃with various cumulative amount of water feed(CAWF) in a fixed bed reactor. The catalytic process was carried out under the following conditions: a temperature of 480 ℃; a methanol WHSV of 3 h-1; a methanol partial pressure of 30 k Pa; and a time on stream of 12 h, 24 h and 48 h, respectively. The BET parameters of catalysts and diffusion coefficients of toluene showed that there were two types of mesopores generated under different hydrothermal conditions. Mild temperature and moderate CAWF conditions led to external open mesopores which could be entered from the external surface of the zeolite, while a high temperature or a high CAWF condition resulted in the generation of macropores or internal isolated mesopores, which were occluded in the microporous matrix. The TGA results showed that catalyst with external open mesopores had good ability to resist coke accumulation and good performance on propylene selectivity, while the internal isolated mesopores did no contribute to the increased diffusivity of reactants and products.
基金The financial support provided by the Project of National Natural Science Foundation of China(21822809&21978256)the National Science Fund for Distinguished Young(21525627)+1 种基金the Fundamental Research Funds for the Central Universities(2019XZZX004-03)Ningxia Collaborative Innovation Center for Value Upgrading of Coal-based Synthetic Resin(2017DC57)。
文摘Hydrogen management is important for refineries to improve their business efficiency.Various approaches such as pinch analysis and mathematical programming have been employed in the management of hydrogen system.However,it is not easy for site engineers to implement these techniques,due to the complicated procedures.At this point,it is necessary to develop a software that can implement the proposed methodologies automatically,which is really the goal of this work.The presented refinery hydrogen system optimization software(RHO)is a web based system.It is developed in the Java Web environment,where the subroutines of mathematical model developed in GAMS software can be easily called.RHO can generate graphics of both the hydrogen pinch diagram and the hydrogen distribution network.The purifiers as well as the physical distances between units are considered in the optimization model.In addition,there is a special module for the calculation of membrane separation,which is very important in the hydrogen network.The functions and the interfaces of the software are illustrated via practical cases.Case studies show the effectiveness of the RHO software.
基金supported by the National Natural Science Foundation of China(No.U1663222).
文摘Acidity plays a vital role in methane conversion by co-feeding method,which is one of the best strategies to improve the utilization and gentle the reaction conditions of methane.In this work,Zn,Ni,Mo,La,Ga,Fe and Co-impregnated ZSM-5 zeolites have been prepared with the same substitutions to variate the acidities and tested in co-aromatization of methanol with methane.It is demonstrated that the new medium-strong acid sites formed by metal and strong acid sites are the key role to activate methane in co-reaction.Zn-modified ZSM-5 catalyst is preferred to exhibit the best methane conversion of 12%,whose aromatic selectivity increases from 27.2%to 52.2%compared with that of HZSM-5.Besides,the addition of methane further improves the production of high-valued aromatics compared with methanol to aromatics(MTA)reaction.
