基于二维传递模型的反应器网络综合

反应器网络综合的任务在于寻求适宜的反应器类型、尺寸及反应单元间的连接关系并确定各反应器的操作条件,其研究方法主要包括超级结构法和目标法,采用的基本单元均为一维理想模型。文中同时考虑传质、传热、流体流动以及反应动力学,通过偏微分方程描述轴向及径向上的温度、浓度分布,建立了二维反应器模型。基于该二维传递模型,采用状态空间构建反应器网络,并以年度总费用为目标函数评价反应器系统的经济性。最后,以提出的模型对环氧丙烷反应器网络进行了优化设计,实例验证了方法的有效性。     

A comparison of auto-thermal and conventional methanol synthesis reactor in the presence of catalyst deactivation

This study proposed a one-dimensional dynamic plug flow model to analyze and compare the performance of an auto-thermal and a conversional methanol synthesis reactor in the presence of catalyst deactivation. An auto-thermal two-stage industrial methanol reactor type is a system with two catalyst beds instead of one single catalyst bed. In the first catalyst bed, the synthesis gas is partly converted to methanol in a water-cooled reactor. In the second bed which is a gas-cooled reactor, the reaction heat is used to preheat the feed gas to the first bed. To analyze the effect of important control variables on the rector performance, steady state and dynamic simulations are utilized to investigate effect of operating parameters on the performance of reactors. The simulation results show that there is a favorable profile of temperature along the two-stage auto-thermal reactor type in comparison with conventional single stage reactor type. In this way the catalysts are exposed to less extreme temperatures and, catalyst deactivation via sintering is reduced. Overall, this study resulted in beneficial information about the performance of the reactor over catalyst life-time.     

Control policies for an industrial acetylene hydrogenation reactor

This paper addresses the problem of finding optimal operational policies for an acetylene reactor for day to day operation. A lumped parameter model based on four main reactions is developed and used to examine the effects of the reactor manipulated variables on key reaction parameters. An optimal and a sub-optimal operational policy which minimize the ethylene loss over time are formulated and the solution techniques are presented. The results indicate that the reactor model is in good agreement with industrial plant data. The performance of the optimal control policy is very similar to the performance of the sub-optimal control policy. However, the sub-optimal formulation, while retaining the dominant features of the optimal response, reduces the computational requirements. Finally, some issues concerning the real-time implementation of an advanced acetylene reactor control scheme are presented. These include the estimation of the optimum regeneration cycle, a recursive model update algorithm, the process optimizer and their overall coordination. A preliminary analysis of the benefits associated with the advanced control scheme suggests a considerable reduction in the yearly ethylene loss.     

A FUNDAMENTAL ANALYSIS OF CONTINUOUS FLOW BIOREACTOR AND MEMBRANE REACTOR MODELS WITH TESSIER KINETICS

In this research we analyze the steady-state operation of a continuous flow bioreactor, with or without recycle, and an idealized or nonidealized continuous flow membrane reactor. The model extends to include a fixed bed reactor where a fraction of the biomass is detached by the flow. The reaction is assumed to be governed by Tessier growth kinetics. We show that a flow reactor with idealized recycle has the same performance as an idealized membrane reactor and that the performance of a nonidealized membrane reactor is identical to that of an appropriately defined continuous flow bioreactor with nonidealized recycle. The performance of all three reactor types can therefore be obtained by analyzing a flow reactor with recycle. The steady states of the recycle model are found and their stability determined as a function of the residence time. The performance of the reactor at large residence times is obtained.     

泰勒流反应器的流动及反应特性

利用由静态混合器、喷嘴和分气盒组成的新型布气装置在搅拌釜式反应器中诱导生成泰勒流,对反应器流动特性及反应特性进行了实验研究。结果表明,与常规搅拌釜式反应器相比,泰勒流反应器内物料流动更加接近于平推流流型,泰勒流的生成在反应器内构建出局部平推流区域,降低了物料返混程度。反应器反应性能因流动特性改变而得以增强,相同实验条件下,在泰勒流反应器中进行的蔗糖水解反应转化率比在常规搅拌釜式反应器中高出26.7%。在一定操作范围内,局部平推流区域和反应转化率均随搅拌转速或进气量的增加而增大。泰勒流反应器可简化为平推流区和全混流区并联的流动模型,推导出了反应转化率与平推流区域占反应器总体积比率之间的关联关系。     

The effects of modes of hydrogen input and reactor configuration on reaction rate and H2 efficiency in the catalytic hydrogenation of alkynol to alkenol

Hydrogenation often involves three phases where hydrogen-on-demand is the typical mode of operation in industrial scale reactors. In research labs and publications, however, continuous hydrogen flow has been used. This paper investigates the effect of such modes of operation on reaction rate using a selective hydrogenation of 3-butyn-2-ol over Pd/Al₂O₃ to obtain 3-buten-2-ol as the model reaction. The two modes of operation were first tested in a commercial PARR stirred tank reactor and then repeated in an oscillatory baffled reactor (OBR) in order to validate the experimental results. Our investigation demonstrates that an enhanced reaction performance and 10 times better H₂ efficiency were obtained when the pressure was maintained constant during the reaction by feeding gas as required, ie hydrogen-on-demand mode. The method of a continuous flow of hydrogen in hydrogenation means that excess hydrogen is vented out when operating at ambient pressures or builds up at elevated pressures. Our work also enables a comparison of reactor designs on reactor performance, and three times higher H₂ efficiency and 2.3 times shorter residence time were achieved when using the OBR instead of the PARR due to its enhanced and uniform mixing, regardless of the mode of operation.     

Dynamics of penicillin G hydrolysis in an electro‐membrane reactor

Analysis of penicillin G hydrolysis in a membrane reactor with membrane‐entrapped penicillin G acylase is performed using a mathematical model of the reactor system. An electric field imposed to the reactor is considered to enhance transport rates of reaction components and reaction rate. Diffusion, electrophoretic migration and electro‐osmotic flux across the membrane are considered. The analysis focuses on possible effects of the principal operational parameters (electric field intensity, inlet substrate concentration, membrane thickness) on reactor performance. Multiplicities of steady states are frequently encountered. The membrane reactor performance can be easily targeted towards the required reaction regime by applying a constant or periodically varying electric field to the system. The periodic alternation of the polarity of the electric field substantially increases the effectiveness factor of penicillin hydrolysis compared with the steady state operation. Proper adjustments of electric field intensity may also compensate for the decay in enzyme activity. © 2001 Society of Chemical Industry     

两种煤气甲烷化反应器的模拟和比较

建立了耐硫甲烷化外冷列管式反应器的拟均相二维模型和外循环式反应器的拟均相一维模型,考察了设备参数和操作条件对反应床层的影响．从反应工程角度考虑,外冷列管式反应器优于外循环式：外冷列管式反应器在近于等温条件下进行;外循环式反应器存在大量产品气的返混,降低了有效气（CO和H2）含量．     

煤加氢液化制取芳烃研究进展

芳烃化合物是一类主要有机化工原料,目前主要从石油化工中获得．我国石油资源紧缺已成为生产芳烃的瓶颈,而煤由于其特殊的芳香性,在一定条件下经加氢液化后得到主要富舍芳烃的液体产品,有望成为石油代替和减缓石油供需矛盾的有效途径之一．对煤加氢液化制取芳烃的可能性、加氢液化工艺进展、煤液化油的组成以及液化油如何制取芳烃的方法等进行了综述和讨论,为进一步开展这一领域的研究工作奠定了基础．     

气固错流移动床高温煤气脱硫过程模拟

在合理假设的基础上，考虑过程的传质和传热，建立了气固错流移动床反应器的数学模型，并采用数值模拟计算方法分析了过程的操作特点．结果表明，由于气固错流接触的特点，气固反应区沿颗粒移动方向逐渐向气体出口侧偏移，在竖直截面上气体浓度存在较大的差异，固体颗粒出口处脱硫剂转化率呈一定的分布．能量衡算表明，反应区温度变化不大，即使考虑到脱硫剂颗粒温度变化，也不会对反应造成太大的影响．在保证高脱硫率的基础上，减小出口脱硫剂转化率分布，提高脱硫剂利用率是反应器优化的关键．     

Dynamic modeling and operability analysis of a dual-membrane fixed bed reactor to produce methanol considering catalyst deactivation

The goal of this research is dynamic operability analysis of dual-membrane reactor considering catalyst deactivation to produce methanol. A dynamic heterogeneous one-dimensional model is developed to predict the performance of this configuration. In this configuration, a conventional reactor has been supported by a Pd/Ag membrane tube for hydrogen permeation and alumina–silica composite membrane tube to remove water vapor from the reaction zone. To verify the accuracy of the considered model, the results of conventional reactor are compared with the plant data. The main advantages of the dual-membrane reactor are: higher catalyst activity and lifetime, higher CO₂ conversion and methanol production.     

Two‐phase model for continuous final‐stage melt polycondensation of poly(ethylene terephthalate). III. Modeling of multiple reactors with multiple reaction zones

A steady‐state two‐phase model has been developed for a continuous finishing stage of the melt polycondensation process that consists of two rotating‐disk reactors in series. Each reactor has multiple reaction zones with different types of rotating disks to establish plug flow profiles and to facilitate the removal of volatile reaction byproducts. The effect on reactor performance of varying the mass transfer parameter was found to be small for the reaction conditions used. The simulation results show that the use of two reactors offers increased flexibility in reactor operations to obtain the desired polymer properties. Although the proposed model has not been fully validated with experimental or plant data, it has illustrated that the complex multizone reactor system can be easily modeled by the two‐phase modeling technique and that added physical insights can be made through numerical model simulations. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1088–1095, 2003     

A porous carbon membrane reactor for the homogeneous catalytic hydration of propene

A porous carbon membrane contactor was studied to determine whether such a reactor could be used for homogeneous catalytic reactions. The hydration of propene, catalysed by an aqueous solution of phosphoric acid, was selected as a suitable model reaction. Experiments at high pressure and temperature were conducted in a laboratory-scale gas phase continuous reactor equipped with a flat carbon membrane contactor. It was shown that reasonably stable operation of the reactor could be achieved at high operating pressures by tailoring the porous structure of the carbon membrane and coupling the reactor with an on-line feedback pressure controller. The reactor operated in a mass transfer limited regime due to mass transfer resistance in the liquid filled membrane pores. Periodic oscillation of transmembrane pressure was shown to reduce mass transfer resistance and considerably improve the overall reactor performance.A dynamic model of the reactor was developed and the results of simulations compared favourably with experiments and the performance of a commercially operated conventional reactor employing a supported liquid phase (SLP) catalyst.     

Enhanced ammonia synthesis in multifunctional reactor with in situ adsorption

A steady-state, one-dimensional mathematical model for a multifunctional reactor with in situ adsorption for ammonia synthesis is developed. The model represents integrated ammonia catalytic equilibrium reaction with ammonia adsorption in a co-current gas-flowing solids-fixed bed reactor (GFSFBR). The model was used for simulating the performance of an industrial-scale reactor, which confirmed that the reactant conversion is significantly higher in the multifunctional reactor in comparison to the conventional reactor under optimal conditions. The analysis of the simulation results shows that the conversion in the GFSFBR stays higher than those in the classical reactor even if much lower temperatures and pressures are used.     

CFD simulation of homogeneous reaction characteristics of dehydration of fructose to HMF in micro-channel reactors

In this work the applicability of the micro-channel reactor technique to the production of promising platform chemical 5-hydroxymethyl furan (HMF) from fructose in aqueous solution is systemically investigated by performing CFD simulations. Influential factors including solvents, residence time distribution of reaction mixtures, heat transfer conditions and micro-channel configurations are evaluated in terms of the reaction performance indices, i.e., conversion of fructose, HMF selectivity and yield. A scale-up method from a single channel to a multiple channel reactor is also proposed. It is demonstrated that: 1) at the single channel scale, controlling residence times and temperature distribution of the reaction mixture within the channel is crucial for enhancing the reaction performance, while different channel configurations lead to marginal improvements; 2) for the scaling-up of the reaction process, a reactor module containing 15 circular parallel channels could be used as module blocks, which can be stacked one by one to meet the required reactor performance and production capacity. The present results show that micro-reactors are quite suitable for HMF production.     

Kinetics and Modeling of Fatty Alcohol Ethoxylation in an Industrial Spray Loop Reactor

The kinetics of the ethoxylation of fatty alcohols catalyzed by potassium hydroxide was studied to obtain the rate constants for modeling of the industrial process. Experimental data obtained in a lab‐scale semibatch autoclave reactor were used to evaluate kinetic and equilibrium parameters. The kinetic model was employed to model the performance of an industrial‐scale spray tower reactor for fatty alcohol ethoxylation. The reactor model considers that mass transfer and reaction occur independently in two distinct zones of the reactor. Good agreement between the model predictions and real data was found. These findings confirm the reliability of the kinetic and reactor model for simulating fatty alcohol ethoxylation processes under industrial conditions.     

Effect of hydrogen combustion reaction on the dehydrogenation of ethane in a fixed-bed catalytic membrane reactor

A two-dimensional non-isothermal mathematical model has been developed for the ethane dehydrogenation reaction in a fixed-bed catalytic membrane reactor. Since ethane dehydrogenation is an equilibrium reaction, removal of produced hydrogen by the membrane shifts the thermodynamic equilibrium to ethylene production. For further displacement of the dehydrogenation reaction, oxidative dehydrogenation method has been used. Since ethane dehydrogenation is an endothermic reaction, the energy produced by the oxidative dehydrogena-tion method is consumed by the dehydrogenation reaction. The results show that the oxidative dehydrogenation method generated a substantial improvement in the reactor performance in terms of high conversions and significant energy saving. It was also established that the sweep gas velocity in the shell side of the reactor is one of the most important factors in the effectiveness of the reactor.     

Comparison of the performance of a direct-contact bubble reactor and an indirectly heated tubular reactor for solar-aided methane dry reforming employing molten salt

A theoretical approach is presented for the comparison of two different atmospheric pressure reactors—a direct-contact bubble reactor (DCBR) and an indirectly heated tubular reactor (IHTR)—to evaluate the reactor performance in terms of heat transfer and available catalytic active surface area. The model considers the catalytic endothermic reactions of methane dry reforming that proceeds in both reactors by employing molten salts at elevated temperatures (700–900 °C) in the absence of catalyst deactivation effects. The methane conversion process is simulated for a single reactor using both a reaction kinetics model and a heat transfer model. A well-tested reaction kinetics model, which showed an acceptable agreement with the empirical observations, was implemented to describe the methane dry reforming. In DCBR, the heat is internally transferred by direct contact with the three phases of the system: the reactant gas bubbles, the heat carrier molten salts and the solid catalyst (Ni-Al₂O₃). In contrast, the supplied heat in the conventional shell-and-tube heat exchanger of the IHTR is transferred across an intervening wall. The results suggest a combination system of DCBR and IHTR would be a suitable configuration for process intensification associated with higher thermal efficiency and cost reduction.     

用于分布式制氢的甲烷蒸汽重整膜反应器的数值模拟

采用反应-分离集成的膜反应器进行分布式制氢,对简化工艺、降低能耗、提升技术经济性至关重要。本文采用数学模型对甲烷蒸汽重整制氢过程膜反应器进行模拟,系统分析了渗透侧操作策略、反应压力、反应温度、钯基膜性能、催化剂性能对反应器行为的影响;并以1m³/h甲烷最大程度转化为目标进行分布式制氢案例分析,详细比较膜反应器技术与“常规反应器+膜分离”工艺技术。结果表明,膜反应器在反应压力30atm（1atm=101325Pa）、反应温度500℃下操作可实现紧凑设计,比“常规反应器+膜分离”工艺技术具有明显优势,但是亟需研发更佳活性（10倍）的钯基膜和催化剂以实现显著的过程强化。模拟结果可为不同规模分布式制氢膜反应器的操作与设计及进一步的性能强化提供指导。     

甲醇制烯烃反应动力学及反应器模型研究进展

甲醇制烯烃（MTO）工艺是现代煤化工领域的研究热点,MTO反应动力学及其反应器模型研究是高效反应器开发和工业装置操作优化的基础。本文综述了甲醇制烯烃反应动力学研究进展,详细论述了机理型动力学模型、八集总动力学模型、五集总动力学模型,指出集总动力学模型适用于描述MTO反应过程,如何考虑水、积炭等因素的影响是MTO动力学研究的难点和关键。结合现有动力学模型,评述了MTO反应过程在工业规模的固定床反应器、提升管反应器、循环流化床反应器、湍动流化床反应器中产物分布和转化率模拟情况,结果表明：循环流化床反应器和湍动流化床反应器适合MTO工业过程。最后指出,甲醇制烯烃反应动力学下一步研究方应集中于工业规模流化床反应器气固两相流动模拟,以及与动力学模型结合获得准确预测工业反应结果的MTO反应器模型。