Operating batch

Consider changing from batch to continuous operation. Batch processes, by their very nature, are always at unsteady state and thus are difficult to maintain at optimal conditions. 

Process A Genetic instability Substrate repression Multi-step synthesis Product (volatile) inhibition Mode of operation Batch Fed-batch Continuous... 

Additionally, the influence of the life time of the micro-structured devices as well as the expenditure of the peripheral equipment was estimated in order to obtain insight into the ecological hot-spots of the system. A conventional macro-scaled semi-continuously operated batch process was chosen as a reference process. The comparison of both technological systems was performed by means of the two-step synthesis of m-anisaldehyde serving as model reaction. 

Factors re.sponsible for the occurrence of scale-up effects can be either material factors or size/shape factors. In addition, differences in the mode of operation (batch or semibatch reactor in the laboratory and continuous reactor on the full scale), or the type of equipment (e.g. stirred-tank reactor in the laboratory and packed- or plate- column reactor in commercial unit) can be causes of unexpected scale-up effects. A simple misuse of available tools and information also can lead to wrong effects. 

Figure 2 shows that the path through the Data Handling Menu is quite restricted, in that some functions cannot be performed without first performing others. This is done because the chromatograph analyzes a group of specimens in one continuous operation (batch mode). Each set of data must be associated with pertinent archival data. 

The next two steps after the development of a mathematical process model and before its implementation to "real life" applications, are to handle the numerical solution of the model s ode s and to estimate some unknown parameters. The computer program which handles the numerical solution of the present model has been written in a very general way. After inputing concentrations, flowrate data and reaction operating conditions, the user has the options to select from a variety of different modes of reactor operation (batch, semi-batch, single continuous, continuous train, CSTR-tube) or reactor startup conditions (seeded, unseeded, full or half-full of water or emulsion recipe and empty). Then, IMSL subroutine DCEAR handles the numerical integration of the ode s. Parameter estimation of the only two unknown parameters e and Dw has been described and is further discussed in (32). 

Contacting patterns for various combinations of high and low concentration of reactants in noncontinuous operations (batch reactors). (Adapted from Chemical Reaction Engineering, Second Edition, by O. Levenspiel. Copyright 1972. Reprinted by permission of John Wiley and Sons, Inc.)... 

Figure 10.7 shows the extended RTN formulated for the benchmark problem. The production process includes diverging and converging material flows, flexible proportions of output goods (task Tj), cyclic material flows (recycling of output from task T3 into state Si), intermediate products which cannot be stored (state nodes S5, S9, S10, S12), and blending of products in task Ti 5. All processing tasks are operated batch-wise with lower and upper bounds on batch sizes. Batch sizes are... 

A manual batch sizing procedure was used to determine constant batch sizes for all operations. Batch sizes for tasks running on the resources i i, R3..., R, R, i 9 are fixed to 10. The batch size of T2, which was experimentally identified as a bottleneck, was chosen as 20. With respect to R(, and R7, the batch sizes for the... 

In this chapter, we describe several ideal types of reactors based on two modes of operation (batch and continuous), and ideal flow patterns (backmix and tubular) for the continuous mode. From a kinetics point of view, these reactor types illustrate different ways in which rate of reaction can be measured experimentally and interpreted operationally. From a reactor point of view, the treatment also serves to introduce important concepts and terminology of CRE (developed further in Chapters 12 to 18). Such ideal reactor models serve as points of departure or first approximations for actual reactors. For illustration at this stage, we use only simple systems. 

Consider a chlorine scrubbing unit operated semi-batch-wise. That is, a system similar to that shown in Fig. 26.7 is operated batch-wise but, periodically, a portion of the contents of the sump are sent to treatment and the sump refilled with fresh caustic. This mode of operation allows continuous treatment of the chlorine-laden vent stream while allowing batch operation without the need for a dual scrubbing-liquor reservoir. 

These procedures operate batch-wise. Continuous sample handling has some advantages over discontinuous handling. The samples are not all available at the same time... 

The Lockheed Corporation, now Lockheed Martin, has designed, constructed, and operated batch and continuous ex situ treatment facilities for acid extraction of contaminants. This technology involves the solubilization of contaminants, followed by the isolation of soluble elements into appropriate forms. The goal of this technology is to minimize the volume of hazardous and radioactive constituents for disposal. Physical separation techniques may be used as pretreatment steps. 

Operation of a batch distillation is an unsteady state process whose mathematical formulation is in terms of differential equations since the compositions in the still and of the holdups on individual trays change with time. This problem and methods of solution are treated at length in the literature, for instance, by Holland and Liapis (Computer Methods for Solving Dynamic Separation Problems, 1983, pp. 177-213). In the present section, a simplified analysis will be made of batch distillation of binary mixtures in columns with negligible holdup on the trays. Two principal modes of operating batch distillation columns may be employed ... 

Distillation can be a batch or a continuous operation. Batch distillation is frequently used in the laboratory for determining the chemical composition of mixed liquids, such as hydrocarbons. In the majority of industrial processes, distillation is continuous. In a hatch operation, the charge material is boiled and vapors are removed continuously, condensed, and... 

The time required to accomplish mixing and addition steps is summarized in Table 9. The differences in elapsed time were thought to reflect those typically encountered in manual operations. Batch yield is also shown in the table for future reference. 

As in any pharmaceutical batch operation, batch uniformity is paramount. Studies by Greiff [7] have shown that when lyophilizing a 3-ml volume of a 2% serum albumin solution in a 10-ml-tubing vial there is a measurable effect of... 

MESH) equations which are solved for the whole column, decanter included and taking into account the liquid-liquid phase split. Numerical treatment of the Differential Algebraic Equation (DAE) system and discrete events handling is performed with DISCo, a numerical package for hybrid systems with a DAE solver based on Gear s method. The column technical features and operating conditions are shown in Table 4. A sequence of two operational batch steps, namely... 

When production volume is sufficient, it is economical to build one plant for one product. Batch production in a single unit may be limited by maximum reactor size. Holdups of greater than 20,000 gal are handled in separate parallel reactors. To use common upstream and downstream facilities, the reactors may not be operated simultaneously but on overlapping schedules. When long reaction times cannot be avoided, the reaction sections operate batch wise however, feeding reactants and recovering products may be continuous for economic reasons. This practice is typical of many processes, such as the saponification of natural fats in intermediate quantities. In the production of ethanol by fermentation, two reactions (saccharification and fermentation) are operated on a batch basis, while hydrolysis (conversion of starch to dextrin) and product recovery by distillation are continuous. 

For the validation purpose, the data from Ref. [100] are used. In this study, absorption experiments were carried out using a baffled vessel operated batch-wise with respect to liquid, and the experimental results were compared with an approximate analytical solution based on the Leveque model. The authors proposed a two-reaction-plane model and achieved a good agreement between theoretical and experimental absorption rates (see Section 9.5.4.5). 

In the last few sections, the implications of operating batch distillation in continuous columns have been discussed. It is observed that for a given batch time and recovery of key component and energy consumption, the CBD operation can be replaced by a continuous column operation using low feed flow rate. Compared to batch columns, the modelling and optimisation tasks become easier with the use of continuous columns. For the same number of passes or reflux intervals with any feed flow rate continuous column operation results in a better recovery compared to conventional batch operation. 

Beyond the nucleation stage, size change in the system can occur by a number of mechanisms as depicted in Fig. 3.2. The prevailing mechanism depends on such factors as the feed particle size and other solid properties, liquid surface tension and viscosity and the mode of operation (batch or continuous). After nucleation has occurred, the predominating growth mechanisms are ... 

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