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Chinese Journal of Chemical Engineering 2023年第6期58卷 244-255页

作者： Danlei Chen Yiqing Luo Xigang Yuan Chemical Engineering Research Center School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300350China State Key Laboratory of Chemical Engineering Tianjin UniversityTianjin 300350China

Cascade refrigeration system(CRS)can meet a wider range of refrigeration temperature requirements and is more energy efficient than single-refrigerant refrigeration system,making it more widely used in low-temperature industry processes.The synthesis of a CRS with simultaneous consideration of heat integration between refrigerant and process streams is challenging but promising for significant cost saving and reduction of carbon emission.This study presented a stochastic optimization method for the synthesis of CRS.An MINLP model was formulated based on the superstructure developed for the CRS,and an optimization framework was proposed,where simulated annealing algorithm was used to evolve the numbers of pressure/temperature levels for all sub-refrigeration systems,and particle swarm optimization algorithm was employed to optimize the continuous variables.The effectiveness of the proposed methodology was verified by a case study of CRS optimization in an ethylene plant with 21.89%the total annual cost saving.

关键词： Optimal design Process systems Particle swarm optimization Simulated annealing Mathematical modeling

Optimization of biofuel supply chain integrated with petroleum refineries under carbon trade policy

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Frontiers of Chemical Science and Engineering 2024年第3期18卷 113-122页

作者： Wenhui Zhang Yiqing Luo Xigang Yuan Chemical Engineering Research Center School of Chemical Engineering and TechnologyTianjin UniversityTianjin300350China State Key Laboratory of Chemical Engineering Tianjin UniversityTianjin300350China

The use of fossil fuels results in significant carbon dioxide emissions.Biofuels have been increasingly adopted as sustainable alternatives to fossil fuel to address this environmental issue.Integrating petroleum refineries into biofuel supply chains is an effective approach to mitigating greenhouse gas emissions and improving environmental sustainability.In this study,an integrated supply chain optimization framework was established,considering the carbon trade policy.In addition,a mixed-integer nonlinear programming model was developed to optimize the selection of biomass suppliers,construction of pretreatment plants and biorefineries,integration of petroleum refineries,and selection of transportation routes with the objective of minimizing the total annual cost.An example is presented to illustrate the applicability of the model.The optimization results show that integrating petroleum refineries into biofuel supply chains effectively mitigates carbon emissions.Carbon trade policies can have a direct impact on the total annual cost and carbon emissions of the supply chain.

关键词： renewable energy biofuel supply chain carbon trade policy

Recent progress on equation-oriented optimization of complex chemical processes

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Chinese Journal of Chemical Engineering 2022年第1期35卷 162-169页

作者： Yuyang Kang Yiqing Luo Xigang Yuan Chemical Engineering Research Center School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300350China State Key Laboratory of Chemical Engineering Tianjin UniversityTianjin 300350China

Process optimization in equation-oriented(EO)modeling environments favors the gradient-based optimization algorithms by their abilities to provide accurate Jacobian matrices via automatic or symbolic differentiation.However,computational inefficiencies including that in initial-point-finding for Newton type methods have significantly limited its application.Recently,progress has been made in using a pseudo-transient(PT)modeling method to address these difficulties,providing a fresh way forward in EO-based optimization.Nevertheless,research in this area remains open,and challenges need to be addressed.Therefore,understanding the state-of-the-art research on the PT method,its principle,and the strategies in composing effective methodologies using the PT modeling method is necessary for further developing EO-based methods for process optimization.For this purpose,the basic concepts for the PT modeling and the optimization framework based on the PT model are reviewed in this paper.Several typical applications,e.g.,complex distillation processes,cryogenic processes,and optimizations under uncertainty,are presented as well.Finally,we identify several main challenges and give prospects for the development of the PT based optimization methods.

关键词： Simulation Optimization Algorithm Pseudo-transient modeling method Equation-oriented optimization Complex chemical processes

Refrigeration system synthesis based on de-redundant model by particle swarm optimization algorithm

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Chinese Journal of Chemical Engineering 2022年第10期50卷 412-422页

作者： Danlei Chen Yiqing Luo Xigang Yuan School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China State Key Laboratory of Chemical Engineering Tianjin UniversityTianjin 300072China

Simultaneous optimization of refrigeration system(RS)and its heat exchanger network(HEN)leads to a large-scale non-convex mixed-integer non-linear programming(MINLP)problem.Conventionally,researchers usually adopted simplifications to confine problem scale from being too large at the cost of reducing solution space.This study established an optimization framework for the simultaneous optimization of RS and HEN.Firstly,A more comprehensive and compact model was developed to guarantee a relatively complete solution space while reducing model scale as well as its solving difficulty.In this model,a tandem arrangement of connecting sub-coolers and expansion valves was considered in the superstructure;and the pressure/temperature levels were optimized as continuous variables.On this basis,we proposed a"two-step transformation method"to equivalently transform the cross-level structure into a no n-cross-level structu re,and the de-redundant superstructu re was established with ensuring comprehensiveness and rigor.Furthermore,the MINLP model was developed and solved by Particle Swarm Optimization algorithm.Finally,our methodology was validated to get better optimal results with less CPU time in two case studies,an ethylene RS in an existing plant and a reported propylene RS.

关键词： Refrigeration system Optimal design Process systems Particle swarmoptimization Mathematical modeling

Festschrift in honor of Professor K.T.Yu(Guocong Yu)and the 40th anniversary of the CJChE

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Chinese Journal of Chemical Engineering 2022年第10期50卷 1-2页

作者： Xigang Yuan Zhibing Zhang Guangjin Chen Tianjin University China Nanjing University China China University of Petroleum(Beijing) China

We are honored to present this special issue of the Chinese Journal of Chemical Engineering(CJChE)as a Festschrift in honor of Professor K.T.Yu(1922.11–2022.4)to commemorate the 100th anniversary of his birth,and celebrate the 40th anniversary of the CJChE,which was co-founded by Prof.K.T.Yu,together with Prof.Chia-yung Chen(Jiayong Chen).

关键词： anniversary honor K

Box-Behnken experimental design for optimizing process parameters in carbonate-promoted direct thiophene carboxylation reaction with carbon dioxide

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Chinese Journal of Chemical Engineering 2022年第10期50卷 222-234页

作者： Qingjun Zhang Youguang Ma Xigang Yuan Aiwu Zeng State Key Laboratory of Chemical Engineering School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300350China Chemical Engineering Research Center Collaborative Innovative Center of Chemical Science and Engineering(Tianjin)Tianjin 300350China

A feasible synthesis route is developed for achieving the direct carboxylation of thiophene and CO_(2) in a relatively mild solvent-free carboxylate-assisted carbonate(semi)molten state.The effects of reaction factors on the carboxylate yield are investigated in the preliminary screening experiments,and the phase behavior analysis of the reaction medium is detected through the thermal characterization analysis of insitu high temperature X-ray diffraction measurement(in-situ XRD).The application of response surface methodology(RSM)based on the Box-Behnken design(BBD)is conducted to investigate the effect of the reaction parameters,such as reaction temperatu re,carbonate proportion,CO_(2) pressure and thiophene amount,on the product yield.The regressed second-order polynomial model equation well correlates all the independent variables.The analysis of variance(ANOVA)results reveal that the quadratic effect of reaction temperature is the most effective parameter in this carboxylation reaction owing to it’s the highest contribution to the sum of square(30.18%).The optimum reaction conditions for maximum product yield are the reaction temperature of 287℃,carbonate proportion of 32.20%,CO_(2) pressure of 1.0MPa and thiophene amount of 9.35 mmol.Operating under these selected experimental conditions,a high product yield(50.98%)can be achieved.

关键词： Carboxylation Solvent-free medium Molten salt Optimization Response surfacemethodology

Direct carboxylation of thiophene with CO_(2) in the solvent-free carboxylate-carbonate molten medium:Experimental and mechanistic insights

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Chinese Journal of Chemical Engineering 2022年第10期50卷 264-282页

作者： Qingjun Zhang Pengyuan Shi Xigang Yuan Youguang Ma Aiwu Zeng State Key Laboratory of Chemical Engineering School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300350China Chemical Engineering Research Center Collaborative Innovative Center of Chemical Science and Engineering(Tianjin)Tianjin 300350China

A feasible synthesis route is devised for realizing direct carboxylation of thiophene and CO_(2) in a relatively mild solvent-free carboxylate-assisted carbonate(semi)molten medium.The effects of reaction factors on product yield are investigated,and the phase behavior analysis of the reaction medium is detected through the thermal characterization techniques.Product yield varies with the alternative carboxylate co-salts,which is attributed to the difference in deprotonation capacity caused by the base effect within the system.Besides,the detailed mechanism of this carbonate-promoted carboxylation reaction is studied,including two consecutive steps of the formation of carbanion through breaking the C-H bond(s)via the carbonate and the nucleophile attacking the weak electrophile CO_(2) to form C-C bond(s).The activation energy barrier in C-H activation step is higher than the following CO_(2) insertion step whether for the formation of the mono-and/or di-carboxylate,which is in good agreement with that of kinetic isotope effect(KIE)experiments,indicating that the C-H deprotonation is slow and the forming presumed carbanion reacts rapidly with CO_(2).Both the activation energy barriers in deprotonation steps are the minimal for the cesium cluster system since there have the weak the cesium Cs-heteroatom S(thiophene)and Cs-the broken proton interactions compared to the K2CO3 system,which is likely to enhance the acidity of C-H bond,lowering the C-H activation barrier.Besides,these mechanistic insights are further assessed by investigating base and C-H substrate effects via replacing Cs2CO3 with K2CO3 and furoate(la)with thiophene monocarboxylate(1b)or benzoate(1c).

关键词： Inert CAH bond Carboxylation Solvent-free medium Base effect Density functionaltheory(DFT)study

Making More Sense of Human Intention Detection via Reconstruction Models

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China Communications 2020年第7期17卷 193-206页

作者： Wei Liang Dalin Zhang Xigang Yuan School of Computer Science and Engineering Changshu Institute of TechnologyChangshu 215500China School of Computer Science and Engineering University of New South Wales2052 NSWAustralia Business School Jiangsu Normal UniversityXuzhou 221116China

Movement intention recognition paves the path to developing Brain-Computer Interface(BCI)applications.Current research mostly focuses on questions like"which hand is intended to move".While answering questions like"whether a hand is intended to move"is more desirable for widely realworld applications,because we cannot continuously perform intention tasks during usage,and the gap periods may cause unintended operation resulting in system failures.However,this kind of intention detection task is more difficult,since for a"whether"problem,it is hard to know what the"not"situation is and consequently to acquire training samples for the"not"situation.Furthermore,the occurrence of genuine intentions is comparatively scarce and unexpected,making the intention detection task hard and computation-consuming.To tackle this problem,we propose a Reconstruction-based Intention Detection(RID)framework,which utilises a reconstruction model to represent a high-level abstraction of EEG signals and leverages the reconstruction errors to determine"whether"there is a movement intention.Our framework is not only theoretically flexible and robust to any sophisticated real-world scenarios but also hand-crafted feature and domain knowledge free.Comprehensive experiments on detecting movement intention tasks with different reconstruction models demonstrate the promising performance of the proposed reconstruction intention detection framework.

关键词： intention consuming mostly

A pseudo transient nonequilibrium method for rigorous simulation of multicomponent separation columns

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Chinese Journal of Chemical Engineering 2023年第10期62卷 57-64页

作者： Jie Wu Yiqing Luo Xigang Yuan School of Chemical Engineering and Technology Tianjin UniversityTianjin 300350China Chemical Engineering Research Center Tianjin UniversityTianjin 300350China State Key Laboratory of Chemical Engineering Tianjin UniversityTianjin 300350China

Nonequilibrium stage model is a significant improvement in multicomponent separation process simulation,but more equations are involved and the solution of the model equations,which relies on an adequate initial guess for convergence of the Newton method,is difficult.In this work,based on the concept of pseudo-transient continuation approach,we proposed a new pseudo-transient(PT)nonequilibrium method.The proposed method decouples the strongly coupled model equations by introducing dynamic equations for material and energy conservation,as well as transition equations.Thus,the steady-state solution of the nonequilibrium stage model can be obtained through a robust and fast integration process,and the initial guess issue in Newton method can be effectively avoided.Two simulation cases were used to demonstrate the advantages and applicability of the proposed PT nonequilibrium method.

关键词： Nonequilibrium stage model Pseudo-transient continuation Distillation Numerical simulation Systems engineering

An optimization method for enhancement of gas–liquid mass transfer in a bubble column reactor based on the entropy generation extremum principle

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Chinese Journal of Chemical Engineering 2023年第1期53卷 83-88页

作者： Chao Zhang Youzhi Liu Weizhou Jiao Hongyan Shen Xigang Yuan Shengkun Jia Shanxi Province Key Laboratory of Higee-Oriented Chemical Engineering North University of ChinaTaiyuan 030051China State Key Laboratory for Chemical Engineering School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China

In this study,an optimization method is proposed to enhance the gas–liquid mass transfer in bubble column reactor based on the entropy generation extremum principle.The mass transfer–induced entropy generation can be maximized with the increase of mass transfer rate,based on which the velocity field can be optimized.The oxygen gas–liquid mass transfer is the major rate–limiting step of the toluene emissions biodegradation process in bubble column reactor,so the entropy generation due to oxygen mass transfer is used as the objective function,and the conservation equations of the gas–liquid flow and species concentration are taken as constraints.This optimization problem is solved by the calculus of variations,the optimal liquid flow pattern is obtained and the relationship of the maximum mass transfer enhancement on viscous dissipation is revealed,which can be used to improve the design of internal structure of the bubble column reactor.

关键词： Entropy generation Bubble column reactor Optimization Biodegradation Flow field