反胶团酶反应过程开发研究进展

反胶团酶反应具有水相与有机相酶反应的共同优点 ,因而受到人们的重视。制约其实际应用的重要原因在于如何解决酶的重复利用问题。最初人们采用水溶液萃取法回收酶 ,但由于条件苛刻 ,酶活回收率较低。相变法利用温度的改变使体系分相以实现酶的回收 ,操作简便 ,但仍有较大的酶活损失。连续流两相离心反应器可以实现反胶团酶反应的连续操作且酶的损失很小 ,但该反应器传质速率较低因而转化率不高。膜反应器是反胶团酶反应中研究最多也最有应用前途的一种反应器形式。文中介绍了反胶团酶反应中酶重复利用的方法 ,对其过程开发的最新进展进行了综述。     

Steady-state simulation of Fluid Catalytic Cracking riser reactors using a decoupled solution method with feedback of the cracking reactions on the flow

A method is proposed to simulate reactive flow, fully taking into account the effect of the reactions on the flow. Operator splitting is used to separate the computation of convection and reaction. A fast solver for mildly stiff ordinary differential equations and parallelization of the reaction term evaluation have been implemented to reduce the CPU time. The proposed method is applied to the steady-state, two-phase gas–solid simulation of a Fluid Catalytic Cracking riser reactor. A relatively simple kinetic model with four lumped components is used to demonstrate the feasibility of the method. The results show that the method is able to handle reactive flow with significant feedback of the reactions on the flow.     

T型反应器内流动、混合及界面反应特征

利用平面激光诱导荧光（PLIF）技术和酚酞显色反应,对不同Reynolds数（20<Re<420）下T型反应器内的复杂流动结构及界面反应进行了可视化研究。随着入口Re的增加,反应器内依次出现分离流、稳态吞噬流、非稳态吞噬流及非稳态对称流等流动模式。重点考察了不同流动模式下T型反应器内的界面反应特征,结合流动模式对混合效果、产物浓度分布及时间演化进行了分析,揭示了反应器内复杂流场对混合及界面反应的影响机理。结果表明,吞噬流三维旋涡结构使流体相互卷吸缠绕,通过折叠拉伸形成层状的流体界面,极大增加了反应物的界面接触面积,混合及反应程度显著提升,产物浓度较高且分布均匀。     

小型提升管反应器流动-反应耦合模拟

在提升管气固两相湍流流动模型和重油反应动力学集总模型的基础上,利用Fluent软件建立了催化裂化提升管反应器气固两相流动与反应耦合模型,对实验室小型提升管反应器进行了数值模拟,考察了气固两相的流动、传热、传质与反应过程。结果表明,提升管反应器内气固两相在轴向和径向的流动、传热与反应的分布不均匀。在入口附近。原料和催化剂温度变化显著,各组分的浓度变化剧烈,在提升管上部,变化平缓。反应器出口各组分质量分数的模拟值和实验值基本吻合。说明该模型对提升管反应器出口参数和反应结果具有较好的预测性。     

CFD analysis of hydrodynamic, heat transfer and reaction of three phase riser reactor

Catalytic cracking reaction and vaporization of gas oil droplets have significant effects on the gas solid mixture hydrodynamic and heat transfer phenomena in a fluid catalytic cracking (FCC) riser reactor. A three-dimensional computational fluid dynamic (CFD) model of the reactor has been developed considering three phase hydrodynamics, cracking reactions, heat and mass transfer as well as evaporation of the feed droplets into a gas solid flow. A hybrid Eulerian-Lagrangian method was applied to numerically simulate the vaporization of gas oil droplets and catalytic reactions in the gas-solid fluidized bed. The distributions of volume fraction of each phase, gas and catalyst velocities, gas and particle temperatures as well as gas oil vapor species were computed assuming six lump kinetic reactions in the gas phase. The developed model is capable of predicting coke formation and its effect on catalyst activity reduction. In this research, the catalyst deactivation coefficient was modeled as a function of catalyst particle residence time, in order to investigate the effects of catalyst deactivation on gas oil and gasoline concentrations along the reactor length. The simulation results showed that droplet vaporization and catalytic cracking reactions drastically impact riser hydrodynamics and heat transfer.     

Characterization of a photocatalytic reaction in a continuous‐flow recirculation reactor system

A continuous‐flow recirculation mode, generally called a recycle mode, is known to be practically meaningless except when the reactant is separated from the product at the reactor exit or when the reaction is autocatalytic, because when simply circulating a small amount of the fluid containing a reactant, the reactant concentration in this mode is lowered due to mixing of the fluid at the reactor entrance, leading to a decrease in the conversion at the reactor exit. This mode may, however, be meaningful in photocatalytic reactions with very large film‐diffusional resistance. To indicate the validity of this estimation, therefore, characteristics of a continuous‐flow recirculation reactor have been investigated both theoretically and experimentally. As a result, it is found that by increasing the circulation flow rate the conversion and productivity in this reactor is higher than that in a continuous‐flow reactor because the film‐diffusional resistance is remarkably reduced. Copyright © 2006 Society of Chemical Industry     

The hydrogenation of isophorone to trimethyl cyclohexanone using the downflow single capillary reactor

Despite many innovations in the intensification of catalytic multiphase reactors for the small and medium scale manufacture of chemicals, there have as yet been relatively few commercial successes. One reason for this might be that many of these developments inherently incorporate a fixed catalyst, which may not suit an industry that is based on principles of batch manufacture and multi-product plant. This study evaluates an intensified reactor that encompasses the opportunities demonstrated from structured flows and thin channels, together with a mobile, slurry catalyst, namely a capillary reactor with gas/liquid/suspended catalyst flow. A downflow single capillary reactor (SCR) was designed, built and evaluated for the selective hydrogenation of isophorone to trimethyl cyclohexanone using commercial Pd- and Rh-based catalysts. Using the single capillary arrangement, the reaction was shown to be operating under kinetic control.

Comparison of the rate of hydrogenation with autoclave showed a significant increase of the reaction rate when capillary reactor was used. The temperature of reaction is a crucial factor in tuning the reaction towards different products. The constant relative reaction rate obtained for different catalyst loading as well as the calculated value of the apparent activation energy show that the reaction of hydrogenation of isophorone is not mass transfer limited in the single capillary reactor.     

Self-Optimizing Reactor Systems: Algorithms,On-line Analytics,Setups, and Strategies for Accelerating Continuous Flow Process Optimization

This review provides an overview of recent developments in the area of continuous flow process optimization by employing self-optimizing reactor systems. Although only few reactor concepts have been realized to date, impressive progress has been made, which now allows fully automated reaction optimization without the need of human interactions.     

连续相变的加氢反应器

引　言加氢反应是一类强放热反应 ,在采用滴流床反应器的情况下 ,经常遇到由于液体分布不均而导致的催化剂不完全润湿的现象[1] 。当液体反应物中含有挥发性组分时 ,在一定条件下 ,液相反应物可能会蒸发 ,伴随着反应速度的突然增加[2 ] ,使催化剂局部过热而失活 .另外 ,由于液体在催化剂床层中的不均匀分布而使床层出现未被润湿的干区 ,在强放热反应中 ,会经常观察到出现热点 ,床层的轴向温度出现振荡[3] .两相并流向上的固定床反应器 ,由于床层内的持液量较高 ,液体分布均匀 ,催化剂能很好地润湿 ,因此有可能避免出现热点[4 ] .这种操作形…     

Computational analysis of an instantaneous chemical reaction in a T‐microreactor

We extend and apply a method for the numerical computation of convective and diffusive mixing in liquid systems with very fast irreversible chemical reaction to the case of unequal diffusivities. This approach circumvents the solution of stiff differential equations and, hence, facilitates the direct numerical simulation of reactive flows with quasi‐instantaneous reactions. The method is validated by means of a neutralization reaction which is studied in a T‐shaped micromixer and compared with existing experimental LIF‐data. Because of their large are‐to‐volume ratio, microreactors are well suited for fast chemical reactions which are seriously affected by the slow diffusive transport in aqueous media. Numerical computations for different reactor dimensions reveal the fact that, in a dimensionless setting, the obtained conversion is independent of the reactor size, if the flow conditions are the same. This corresponds to an increase of space‐time‐yield proportional to the square of the inverse scale factor. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Understanding and optimization of chemical reactor performance for bimodal reaction sequences

The relative contributions of heterogeneously catalyzed and homogeneous bulk phase reactions in bimodal reaction sequences have been assessed via 1D reactor simulations. Starting from a reaction network only comprising two parallel, irreversible heterogeneously catalyzed and homogeneous bulk phase steps, complementary consecutive steps were included with the option of being reversible. The final product formed after a minimum number of homogeneous bulk phase reactions is obtained with high yields in continuous flow fixed bed reactors. The products obtained after a higher number of homogeneous bulk phase reactions generally dominate in slurry reactors. Yields of the latter may exhibit an optimum as a function of the catalyst amount in the reactor. The adsorption enthalpies of the intermediates in the reaction network critically determine the position and shape of this maximum. The reversibility of the homogeneous bulk phase steps provides specific opportunities to tune the product yields in bimodal reaction sequences. © 2016 American Institute of Chemical Engineers AIChE J, 63: 111–119, 2017     

等离子体射流裂解甲烷制乙炔的数值模拟

针对漏斗形射流反应器中热等离子体法裂解天然气制乙炔的过程进行研究.采用k-ε双方程模型对体系中的传递过程进行模拟,并通过甲烷裂解系列反应的宏观动力学模型对反应过程进行耦合.运用CFD方法进行数值求解,得到了反应器内的速度场、浓度场、温度场和反应速率分布.研究结果表明, 漏斗形结构有利于反应器中温度和浓度的良好混合,使得甲烷充分反应;甲烷与乙烯的裂解反应主要沿温度混合面进行,炭黑浓度则沿反应器轴向逐渐增多.对应于本反应器,在等离子体发生器功率为100 kW,甲烷体积流量为10 m³·h^-1时,甲烷转化率和乙炔收率同时达到最大.模拟结果与实验数据吻合较好,验证了模型与模拟结果的合理性.     

Extents of reaction and flow for homogeneous reaction systems with inlet and outlet streams

For homogeneous reaction systems with inlet and outlet streams, this article proposes a linear transformation of the number of moles vector into three distinct parts, namely, the reaction variants, the inlet‐flow variants, and the reaction and inlet‐flow invariants. The transformed states can be interpreted physically as (i) the amount of material contributed by each reaction and still present in the reactor (extents of reaction), (ii) the amount of material contributed by each inlet stream and still present in the reactor (extents of inlet flow), and (iii) the fraction of the initial conditions that has left the reactor (extent of outlet flow). Furthermore, several implications of being able to compute the extents of reaction and inlet flow are discussed. The methodology is illustrated in simulation via the ethanolysis of phthalyl chloride. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

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 determination of possibility of multiple steady states for complex catalytic reactions in an isothermal CSTR

A class of complex reaction networks with deficiency from two to six, involving isothermal catalytic reactions in a continuous flow stirred tank reactor (CSTR), is determined to have the capacity to admit multiple positive steady states by implementation of the combination of the Deficiency One Algorithm and the Subnetwork Corollary. A set of rate constants and two corresponding positive steady states, one stable and the other one unstable, are constructed for four examples.     

2,4,6-三磺酸基间苯二酚硝化——反应动力学与过程优化

采用管式反应器与间歇反应器串联的方式考察了2,4,6-三磺酸基间苯二酚(TSR)选择性硝化制备2-磺酸基-4,6-二硝基间苯二酚(DNRS)的过程。建立了三步串联硝化反应宏观动力学模型以及等温均相间歇反应器模型(BR),对实验数据进行优化拟合估计动力学参数:将获得的动力学参数应用于一维定态轴向扩散管式反应器模型(LM)中,并与实验值进行对比验证。结果表明,三步串联硝化反应的表观活化能分别为57.66,40.05,130.89 kJ/mol;轴向扩散降低了串联硝化反应中间产物的选择性及收率,目标产物DNRS的最大收率随着管式反应器管径的增加而减小。分析比较了LM模型与BR模型的计算结果,并对管式反应器的放大进行了模拟计算。研究结果可用于TSR硝化反应器的设计和过程的优化。     

Bromate Ion Formation: Impact of Ozone Contactor Hydraulics And Operating Conditions

This paper presents a simplified kinetic reaction rate model which enables the evaluation of various contactor hydraulics on bromate ion formation. Two extreme reactor types are presented: completely stirred tank (CSTR) and plug flow reactors (PFR). The kinetic modeling has been based on reactions and rate constants for molecular ozone mechanisms. At this stage, the work presented does not take into account the formation and reaction of hydroxyl radicals in the reaction pathway. However, for further in-depth modeling consideration, it is questionable that no hydroxyl radicals are formed. Similar bromate ion levels were predicted with a PFR and a CSTR for similar operating conditions in the case of predominantly molecular ozone reactions. However in most cases, a CSTR will require a much higher Cτ (product of the residual ozone concentration and the hydraulic residence time) than a plug flow reactor in order to achieve similar treated water quality goals.     

Investigations on Selectivity of Gas-Liquid Reactions in Capillaries

Biocatalysis offers a broad spectrum of possible ecological and economic advantages over conventional chemical catalysis processes, e.g., lower energy consumption and high enantio selectivity. The focus of this work is on gas-liquid reactions. These are of great importance in the chemical and biochemical industry and subject of current research since they are often limited by mass transfer or show low selectivity. Different suitable biocatalytically gas-liquid reaction systems were tested in capillary reactor designs in order to obtain information about the interaction between reaction and fluid mechanics. Furthermore, an optical measuring method was established. The experiments were performed in batch mode in a glass beaker with a flow cuvette for UV/Vis measurement of product concentration.     

Catalytic reaction performed in the liquid–liquid system at batch and semibatch operating mode

Hydrolysis of the propionic anhydrite catalysed with sulphuric acid at batch and semibatch operating conditions has been investigated using the reaction calorimeter RC1 Mettler Toledo. Due to a limited solubility of the anhydrite in the aqueous phase where the reaction takes place, mass transfer with simultaneous chemical reaction has to be considered. Contributions of both phases to the reaction mixture change during the reaction progress, so that a complex, strongly non-linear behaviour of the reactor has been noticed. Influence of the concentration of the catalyst, the reaction temperature as well as the initial volume fraction of the organic phase in the reaction mixture and the stirrer speed on the overall conversion rate have been determined directly from calorimetric measurements. Some indications related to the safe and efficient performance of the investigated process as well as to a simplified experimental kinetic model have been formulated.