Proper choice of reactors

Other important aspects to consider during the scaling-up of ionic liquid synthesis are heat management (allcylation reactions are exothermic ) and proper mass transport. For both of these the proper choice of reactor set-up is of crucial importance. 

When formulating an electro-organic synthesis on a laboratory scale, the proper choice of reactor, electrolyte composition, and electrode materials must be made. 

Deposition has serious effects in practical applications. To solve this problem, at this point, we can only suggest to choose proper channel wall material for the reaction system. The material can be chosen based on affinity balance between particle-particle, particle-solvent, and solvent-wall. Besides the physical or physicochemical affinities, chentical affinities such as solidification by surface reaction between adsorbed ions and dissolved ions can also induce deposition. If the affinity between particle and wall is smaller than that between solvent and wall, particles are expected not to be deposited on the wall. Therefore, the proper choice of reactor wall or surface modification can be good optifMis (Fig. 9) [9]. Also, the proper choice of surfactants is also helpful. However, as far as our knowledge is concerned, it is very difficult to obtain general solutions to the deposition problem, and a good combinatimi of reactor material, reaction system, and operation conditions is required. 

The proper choice of material is now a quite different one. Reinforced concrete is now the best choice - that is why many water towers, and pressure vessels for nuclear reactors, are made of reinforced concrete. After that comes pressure-vessel steel - it offers the best compromise of both price and weight. CFRP is very expensive. 

It is assumed that most of the monomer has undergone solution polymerization in a batch reactor resulting in a high solids content and a relatively low monomer concentration, herein designated Mq. At this point a certain amount of initiator is to be added to bring the initiator concentration to Iq. It is desired to reduce the monomer concentration Mq to a final concentration Mf (around 0.5 vol%) in the minimum possible time by proper choice of a temperature policy. 

To do this, not only must he know the chemistry of the reactions but he must know the rates at which the reactions occur and what affects those rates. The study of this is called chemical kinetics. By the proper choice of raw materials and operating conditions for the reaction stage the process designer can manipulate the ratio of products formed. One major variable is the temperature. An increase in temperature usually causes the reaction rates to increase, but some increase faster than others. Thus, the product mix in the reactor is dependent on the temperature. The pressure and the time the material spends in the reactor also affects the results. In the gaseous phase ahigh pressure will impede those steps in which the number of moles is increased and assist those in which the number of moles is decreased. A... 

The batch-batch reactor becomes a practical device when the characteristic times for reaction and deactivation are of the same order of magnitude. If they are not and if deactivation is much slower, then C oo becomes very low and difficult to measure accurately. Fortunately, this ratio can be controlled by the experimenter by proper choice of W V. 

Boosting the weakest step in the rate by a proper choice of particle size, solid loading and reactor type can strongly affect the overall economics of the process. 

As the temperature at which significant initiator decomposition takes place depends on the initiator itself, a successful operation of the reactor requires a proper choice of the initiator in many cases, suitable mixtures of different initiators are also used. The reactor performances are often enhanced by a proper use of multiple feed streams of cold ethylene and/or initiator (s). 

The proper choice of anode material, cathode material and reactor material are of particular importance in conducting WEO treatments. The reaction takes place high temperature at oxidizing conditions in the presence of organics and salts, which make the reaction environment extremely corrosive. 

Temperature control for laboratory reactors is typically easy because of high heat transfer area-reactor volume ratios, which do not require large driving forces (temperature differences) for heat transfer from the reactor to the jacket. Pilot- and full-scale reactors, however, often have a limited heat transfer capability. A process development engineer will usually have a choice of reactors when moving from the laboratory to the pilot plant. Kinetic and heat of reaction parameters obtained from the laboratory reactor, in conjunction with information on the heat transfer characteristics of each pilot plant vessel, can be used to select the proper pilot plant reactor. 

Figure 4.10 illustrates the results of typical calculations of the reaction mixture composition evolution in the plug flow reactor the calculations are made using the preceding relationships, the relevant mass balance equa tions, and literature data on Kpi at 210° C. The evolution in time of the ini tial product concentrations including DEB is seen to lead eventually to the situation when the inlet and outlet DEB concentrations become equal. This means that the proper choice of the composition of the initial reaction mix ture makes the process 100% selective in respect to the conversion of the initial reactants, benzene and ethylene, to EB (see Figure 4.10) even though no transalkylation reactor is used. 

In this chapter, we discuss reactor selection and general mole balances for multiple reactions. First, we describe the four baste types of multiple reactions series, parallel, independent, and complex. Next, we define the selectivity parameter and discuss how it can be used to minimize unwanted side reactions by proper choice of operating conditions and reactor selection. We then develop the algorithm that can be used to solve reaction engineering problems when multiple reactions are involved. Finally, a number of examples are given that show how the algorithm is applied to a number of real reactions. 

The catalyst is contained in special reactors (Fig. 10-9) designed to withstand the pressures and temperatures used. By heat interchange either in the reactor or in special heat exchangers, the heat of the reaction—some 24,620 cal per g mole of methanol formed—is absorbed. Some of this is used to heat the entering gas to reaction temperature. By proper choice of the space time yield or, in other words, the amount of methanol produced per volume of catalyst per hour and the amount of heat removed in the heat exchangers, the temperature of the catalyst can be kept reasonably constant. Once started, the reaction is self-supporting i.c., the problem is one of heat removal and not addition. 

The intrinsic complexity of three phase systems creates some difficulties in the scale-up and in the prediction of performances of three phase reactors. But this complexity is also often a serious advantage, as the simultaneous occurrence of three phases offers such a large number of design possibilities that almost all technical and chemical problems (heat removal, temperature control, selectivity of the catalyst, deactivation, reactants ratio etc..,) can be solved by a proper choice of the equipment and of the operating conditions. For example, countercurrent flow of gas and liquid can be used to overcome thermodynamic limitations and solvent effects can be used to improve selectivity and resistance to poisoning of the catalyst. 

Because of its inherent brittleness, polystyrene homopolymer itself has limited application in blends. However, its impact-modified version, viz., HIPS, is more widely used. HIPS itself is a reactor-made multiphase system with 5-13 % polybutadiene ( cis -rich) dispersed as discrete particles in the polystyrene phase, with an optimum particle size of mean diameter of 2.5 pm. The rubber in HIPS is chemically grafted to some extent to the polystyrene. The effective volume of the rubber dispersion is actually increased through the occlusion of some polystyrene. To optimize the impact strength, the rubber particle size (>2.5 pm) and the distribution is normally controlled by the agitation and the proper choice of other process conditions during the polymerization. The property improvements in HIPS, viz., increased impact strength and ductility, are accompanied by the loss in clarity and a decrease in the tensile strength and modulus compared to the unmodified polystyrene. 

At this stage it is likely that an efficient and stable plasma confinement can be achieved by a proper choice of the parameters of Intrap systems. If this comes to be true, such systems of a technologically feasible size can hardly be ruled out as potential neutron sources and reactors, even if more detailed investigations are needed on the fusion technological side. 

The primary purpose of the present section is to exhibit the various interface conditions that have been proposed for use in control-rod calculations. It is of interest to mention that the accuracy of the entire computation is very much dependent on the proper choice of the interface condition for the fast flux. In the analyses which follow we consider a number of such choices and show how the appropriate criticality relation is derived for each case for both a solid and a hollow control rod. This section is concluded with a numerical example which compares the effectiveness of these two types of rods when fully inserted in the center of a bare cylindrical reactor. 

There are some problems encountered such as residential time distribution and deposition on the wall. The residential time distribution can induce widening of the particle size distribution. This can be solved by proper design of the reactor or designing the operation such that the reaction time is reduced or by introducing segmented flow. The deposition of reactant on the wall can cause critical problems because it can induce clogging, uncontrollable flow, particle size distribution widening, and reduction of product yields. To solve these problems, proper choice of reaction systems and wall materials is necessary. Furthermore,... 

It was shown [163 that there are two stable stationary solutions for a proper choice of the control parameter values. With Xq = 20, Bq = 62.5, Dq = 750, the system is bistable for 0 < kc < 1.68. These values are used in the rest of the work. One and two dimensional model-reactors were used. In a one dimensional reactor of length , the convection velocity is all along equal to If the space is dis-... 

There are several possible arrangements for the application of supported catalysis in microreactors. The simplest system involves a micro-fixed-bed reactor with a supported catalyst To provide good mechanical stability, the support is deposited onto glass beads by dip coating or other sol-gd methods. Near-isothermal reactor operation can be realized in a microreactor by the effective dissipation of reaction heat by a proper choice of thermal conductivity and geometry of the plate material and the reactor [22,23]. 

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