Reactor operating conditions, optimum

At the beginning of Sec. 10.2.b, it was stated that after the solution to the mass balance is used to decide the reactor operating conditions for optimum conversion (or selectivity), then the energy balance is utilized to determine the external conditions required to maintain the desired temperature. Thus, Eq. 10.2.b-l is solved together with the steady-state form of Eq. 10.2.a-5 ... 

Optimization of reactor operation policy is of paramount importance if improvement of product quality and increase of business profits are sought. In very specific terms, optimization of the reactor operation conditions is equivalent to producing the maximum amount of polymer product, presenting the best possible set of end-use properties, with minimum cost under safe and environmentally friendly conditions. This optimum solution is almost always a compromise. Increase of polymer productivity is usually obtained with the increase of the operational costs (increase of reactor volumes, reaction temperatures and reaction times, for instance). Besides, the simultaneous improvement of different end-use properties is often not possible (the improvement of mechanical performance is usually obtained through increase of molecular-weight averages, which causes the simultaneous increase of the melt viscosity and decrease of product processibihty). Therefore, the optimization can only be performed in terms of a relative balance among the many objectives that are pursued. 

The above analysis, while referring to the isomerization reaction, is however typical of the analyses that have to be made for all industrial processes in order to determine the economically-optimum reactor operating conditions. 

Exploration for an acceptable or optimum design of a new reaction process may need to consider reactor types, several catalysts, specifications of feed and product, operating conditions, and economic evaluations. Modifications to an existing process hkewise may need to consider many cases. These efforts can oe eased by commercial kinetics services. A typical one can handle up to 20 reactions in CSTRs or... 

Previously, we performed single- and multi-response optimization works in order to address optimal catalyst composition (%CaO and %MnO) and optimal operating conditions (temperature and CO2/CH4 feed ratio [3]. The maximum C2 selectivity and yield of 76.6% and 3.7%, respectively were achieved in multi-responses optimization over the 12.8% CaO-6.4% Mn0/Ce02 catalyst corresponding to the optimum reactor temperature being 1127 K and CO2/CH4 ratio being 2 [3]. The recent contribution on the catalyst technology of CO2 OCM was... 

When the reaction was performed in the microreactor, the maximum conversion of 97.0 % was attained when the flow rate of Boc-AMP solution was 9 ml/min and the molar equivalents of KOH to Boc-AMP was 13 as shown in Fig. 1. Optimum operating conditions were obtained from a statistical method by using factorial design [6]. The yield decreased over the KOH equivalency of 13 in Fig. 1, since the phase separation between the t-Boc20 and the aqueous phase was observed due to the increased water content with increasing KOH equivalency. As the heat transfer performance of the microreactor was greatly improved compared with conventional reactors, higher reaction temperature could be admissible. 

Semibatch reactors are operated in two different modes (1) Some components of the reaction mixture are loaded into the reactor. After the operating conditions have reached the required level, the other components are dosed continuously or portion-wise, whereby temperature and pressure are kept as close as possible to profiles determined as optimum ones. This mode of... 

The reactor performance may be specified independently of the detailed design of the reactor. The conditions for the optimum, or near optimum, performance may be known from the operation of existing plant or from pilot plant studies. 

Table 3.1 Optimum operating conditions for the hydrodynamic cavitation reactors No. Property Favorable conditions...

For the parallel reactions in equation 10.7.1 one may use this general rule to select the follpw-ing operating conditions as optimum from a selectivity viewpoint when the reactor operates isothermally. 

Novel Processing Schemes Various separators have been proposed to separate the hydrogen-rich fuel in the reformate for cell use or to remove harmful species. At present, the separators are expensive, brittle, require large pressure differential, and are attacked by some hydrocarbons. There is a need to develop thinner, lower pressure drop, low cost membranes that can withstand separation from their support structure under changing thermal loads. Plasma reactors offer independence of reaction chemistry and optimum operating conditions that can be maintained over a wide range of feed rates and H2 composition. These processors have no catalyst and are compact. However, they are preliminary and have only been tested at a laboratory scale. 

It is obvious from the above discussion that porous and dense membranes form two different cases, each with its own advantages and disadvantages. Dense membranes, (permeable only to one component) operating at optimum conditions, can be used to obtain complete conversions. However, because the permeation rate is low, the reaction rate has also to be kept low. Porous membranes (permeable to all components but at different permselectivities) are limited under optimum conditions to a maximum conversion (which is not 100%) due to the permeation of all the components. The permeation rates through porous membranes are, however, much higher than those through dense membranes and consequently higher reaction rates or smaller reactor volumes are possible. 

Evaluating this quantity gives the optimum operating conditions of a mixed reactor as... 

For purposes of plant design and for optimum operation consistent with feed stock availability, it is necessary to be able to predict accurately the octanes of the alkylate produced under varying operating conditions. Such a correlation developed from several hundred pilot plant and commercial plant tests is presented in Figures 7, 8, and 9. This correlation is applicable to sulfuric acid alkylation of isobutane with the indicated olefins, and was developed specifically for the impeller-type reaction system, although it also appears to be satisfactory for use with some other types of reactors. 

Studies in optimization-III The optimum operating conditions in sequences of stirred tank reactors. Chem. Eng. ScL 13, 75-81 (1960). 

Chemical reactor design For homogeneous flow reactions, a digital computer can determine the optimum combination of reactor type and operating conditions (with G.T. Westbrook). Ind. Eng. Chem. 53, 181-186 (1961). 

One of the major drawbacks to defining the influence of the feedstock on the process is that the research with respect to feedstocks has been fragmented. In every case, a conventional catalyst has been used, and the results obtained are only valid for the operating conditions, reactor system, and catalyst used. More rigorous correlation is required and there is a need to determine the optimum temperature for each type of sulfur compound. In order to obtain a useful model, the intrinsic kinetics of the reaction for a given catalyst should also be known. In addition, other factors that influence the desulfurization process such as (1) catalyst inhibition or deactivation by hydrogen sulfide, (2) effect of nitrogen... 

Several operating conditions have been found which satisfy the requirements for no coke formation. The optimum S/C ratio at 3.5 appears to fulfill the requirements for temperatures around 800°C for steam reforming process. The optimum O/C and S/C ratios are found 0.45 and 1.5 respectively for ATR reactor simulations at the inlet temperature of 700°C. 

Most reactors used in industrial operations run isother-mally. For adiabatic operation, principles of thermodynamics are combined with reactor design equations to predict conversion with changing temperature. Rates of reaction normally increase with temperature, but chemical equilibrium must be checked to determine ultimate levels of conversion. The search for an optimum isothermal temperature is common for series or parallel reactions, since the rate constants change differently for each reaction. Special operating conditions must be considered for any highly endothermic or exothermic reaction. 

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