考虑水力学可行性的反应精馏塔板持液量设计及优化
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摘要
以筛板塔为塔板基础构型,以原料转化率最大为目标,以塔径和出口堰高为主要调节参数,以塔板水力学可行性为约束条件,建立了一种可优化塔板液相持液量的塔板结构设计方法.塔模拟计算在AspenPlus平台上进行,化学反应采用动力学方程表达,塔板水力学计算采用Cup-Tower软件.结果表明,本设计方法应用于DPC反应精馏过程,在满足流体力学可行性条件下,塔板上液相持液量比基础设计提高了1.39倍,苯酚转化率提高了33.6%.
The liquid holdup is limited by the physical space of the column and should not be appointed at random. To obtain the design and optimization of liquid holdup on reactive distillation trays, an optimization of tray configuration framework considering hydrodynamic feasibility was proposed. The effect of the liquid holdup on the reaction was studied, and the most optimal liquid holdup was obtained, through simultaneous design of three aspects of the liquid holdup, tray configuration and the hydrodynamic feasibility.Using the synthesis of diphenyl carbonate(DPC) by the transesterification of dimethyl carbonate(DMC) with phenol(PhOH) as an example, the implemented process of this method was described in detail. In the process of implementation, sieve tray was employed as illustrated configuration according to the traditional design method of distillation tray, with the maximum reactants conversion as objective function, weir height and column diameter of tray as decision variable and hydrodynamic feasibility of tray as constraints, a step-by-step simulation and design method was developed to achieve the optimization of liquid holdup on reactive distillation trays. Aspen Plus and Cup-Tower software were used to conduct the process simulation with chemical reaction kinetics and hydraulic computation respectively. The results showed that, the weeping was the main limiting factor to increase the liquid holdup. In the column with a diameter of 0.7 m and 0.06 m weir height, the maximum liquid holdup of 18.5 L was obtained, compared to the basic design an increase of holdup of tray by 1.39 times and PhOH conversion by 33.6% under the condition of satisfying hydraulic feasibility could be obtained. The temperature of the reboiler did not exceed 195 ℃ with optimizing the liquid holdup. In addition, the reaction rate of PhOH was higher than that of the initial design, which showed the validity of the proposed method for the DPC reactive distillation process.
The liquid holdup is limited by the physical space of the column and should not be appointed at random. To obtain the design and optimization of liquid holdup on reactive distillation trays, an optimization of tray configuration framework considering hydrodynamic feasibility was proposed. The effect of the liquid holdup on the reaction was studied, and the most optimal liquid holdup was obtained, through simultaneous design of three aspects of the liquid holdup, tray configuration and the hydrodynamic feasibility.Using the synthesis of diphenyl carbonate(DPC) by the transesterification of dimethyl carbonate(DMC) with phenol(PhOH) as an example, the implemented process of this method was described in detail. In the process of implementation, sieve tray was employed as illustrated configuration according to the traditional design method of distillation tray, with the maximum reactants conversion as objective function, weir height and column diameter of tray as decision variable and hydrodynamic feasibility of tray as constraints, a step-by-step simulation and design method was developed to achieve the optimization of liquid holdup on reactive distillation trays. Aspen Plus and Cup-Tower software were used to conduct the process simulation with chemical reaction kinetics and hydraulic computation respectively. The results showed that, the weeping was the main limiting factor to increase the liquid holdup. In the column with a diameter of 0.7 m and 0.06 m weir height, the maximum liquid holdup of 18.5 L was obtained, compared to the basic design an increase of holdup of tray by 1.39 times and PhOH conversion by 33.6% under the condition of satisfying hydraulic feasibility could be obtained. The temperature of the reboiler did not exceed 195 ℃ with optimizing the liquid holdup. In addition, the reaction rate of PhOH was higher than that of the initial design, which showed the validity of the proposed method for the DPC reactive distillation process.
引文
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[12]吴德荣.化工工艺设计手册,第4版[M].北京:化学工业出版社,2009:485-497.Wu D R.Chemical process design handbook,fourth Ed.[M].Beijing:Chemical Industry Press,2009:485-497.
[13]Gilbert K C.Packed column internals[J].Chem.Eng.,1984,91(5):40-51.
[14]Zavaleta-aguilar E W,Sim?es-Moreira J R.Thermal design of a tray-type distillation column of an ammonia/water absorption refrigeration cycle[J].Appl.Therm.Eng.,2012,41(4):52-60.
[15]Rodríguez-ángelesa M A,Gómez-Castrob F I,Segovia-Hernández J G,et al.Mechanical design and hydrodynamic analysis of sieve trays in a dividing wall column for a hydrocarbon mixture[J].Chem.Eng.Process.Process Intensif.,2015,97:55-65.
[16]张磊.酯交换合成二苯酯反应器选型及工艺流程优化研究[D].青岛:中国海洋大学,2016:30.Zhang L.Study on reactor selection and process optimization of the system for the synthesis of diphenyl carbonate by transesterification[D].Qingdao:Ocean University of China,2016:30.
[17]Baur R,Krishna R.Hardware selection and design aspects for reactive distillation columns:a case study on synthesis of TAME[J].Chem.Eng.Process.Process Intensif.,2002,41(5):445-462.
[2]Taylor R,Krishna R.Modeling of reactive distillation-review[J].Chem.Eng.Sci.,2000,55(22):5183-5229.
[3]Shah M,Kiss A A,Zongervan E,et al.Evaluation of configuration alternatives for multi-product polyester synthesis by reactive distillation[J].Comput.Chem.Eng.,2013,52(10):193-203.
[4]May-Vázquez M M,Rodríguez-ángeles M A,Gómez-Castro F I,et al.Hydrodynamic feasibility of the production of biodiesel fuel in a high-pressure reactive distillation column[J].Chem.Eng.Process.Process Intensif.,2017,112:31-37.
[5]Haubrock J,Raspe M,Versteeg G F,et al.Reaction from dimethyl carbonate to diphenyl carbonate.1.experimental determination of the chemical equilibria[J].Ind.Eng.Chem.Res.,2008,47(24):9854-9861.
[6]殷霞,马飞,李建国,等.碳酸二甲酯与苯酚反应动力学及工艺研究进展[J].化学工程,2013,41(12):1-4.Yin X,Ma F,Li J G,et al.Progress in reaction dynamics and process of transesterification of dimethyl carbonate and phenol[J].Chemical Engineering,2013,41(12):1-4.
[7]张磊,林子昕,安维中,等.酯交换合成碳酸二苯酯反应精馏塔的模拟与优化[J].计算机与应用化学,2015,32(12):1429-1433.Zhang L,Lin Z X,An W Z,et al.Simulation and optimization of a reactive distillation column for the synthesis of diphenyl carbonate via transesterification[J].Computers and Applied Chemistry,2015,32(12):1429-1433.
[8]Haubrock J.The process of dimethyl carbonate to diphenyl carbonate:thermodynamics,reaction kinetics and conceptual process design[D].Enschede:University of Twente,2007:166.
[9]Hong C,Fair J R.Prediction of point efficiencies on sieve trays.2.multicomponent systems[J].Ind.Eng.Chem.Process Des.Dev.,1984,23(4):820-827.
[10]Chilton T H,Colburn A P.Mass transfer(absorption)coefficients:prediction from data on heat transfer and fluid friction[J].Ind.Eng.Chem.,1934,26(11):1183-1187.
[11]Zuiderweg F J.Sieve trays:a view on the state of the art[J].Chem.Eng.Sci.,1982,37(10):1441-1464.
[12]吴德荣.化工工艺设计手册,第4版[M].北京:化学工业出版社,2009:485-497.Wu D R.Chemical process design handbook,fourth Ed.[M].Beijing:Chemical Industry Press,2009:485-497.
[13]Gilbert K C.Packed column internals[J].Chem.Eng.,1984,91(5):40-51.
[14]Zavaleta-aguilar E W,Sim?es-Moreira J R.Thermal design of a tray-type distillation column of an ammonia/water absorption refrigeration cycle[J].Appl.Therm.Eng.,2012,41(4):52-60.
[15]Rodríguez-ángelesa M A,Gómez-Castrob F I,Segovia-Hernández J G,et al.Mechanical design and hydrodynamic analysis of sieve trays in a dividing wall column for a hydrocarbon mixture[J].Chem.Eng.Process.Process Intensif.,2015,97:55-65.
[16]张磊.酯交换合成二苯酯反应器选型及工艺流程优化研究[D].青岛:中国海洋大学,2016:30.Zhang L.Study on reactor selection and process optimization of the system for the synthesis of diphenyl carbonate by transesterification[D].Qingdao:Ocean University of China,2016:30.
[17]Baur R,Krishna R.Hardware selection and design aspects for reactive distillation columns:a case study on synthesis of TAME[J].Chem.Eng.Process.Process Intensif.,2002,41(5):445-462.