Batch operating mode

Structural changes of the temporal superstructure can generate different operating modes (batch or semibatch). The reactants that are fed at the beginning of a batch are treated as feed streams at the start of the network, while the intermediate batch feeds, semicontinuous feeds and product takeoffs are represented as sidestreams feeding to, or withdrawing from, the network at different time intervals3. 

The different operation modes used in microbial fermentations are employed also in animal cell cultivation. Although many different classifications can be adopted, the most general is the one that considers the following operation modes batch, fed-batch, continuous, and perfusion, which is a continuous mode with cell recycle/retention (Castilho and Medronho, 2002). 

The classification in Figure 5 serves the description of the reactors used. Here, two ideal contacting types are used, the plug flow mode and the ideally mixed mode, both for the fluid and the solid phase. By appi-cation of the design equations of these ideal reactor types the experimental results are interpreted in a straightforward manner. For two phases, two contacting types and two operation modes (batch and flow) eight combinations arise ... 

To guide the reactor selection process, Walas [7] has classified reactions according to the operating mode (batch or continuous), reactor type (tank, tank battery, tubular), flow type (back mixed, multistage back mixed), and the phases in contact. This reactor classification in Table 7.2 indicates if a particular reactor arrangement is commonly used, rarely used, or not feasible. 

The Fmoc/tBu method has been adopted universally and can be used in any operational mode, batch, or flow and can be utilized for any peptide or modified peptide objective. The methodology has been comprehensively described in books and reviews. 

The first step in the design of a chemical reactor is the selection of the operating mode— batch or continuous. The selection is made on the basis of both economic... 

Filtration equipment is commercially available in a wide range. Proper selection must be based on detailed information of the slurry to be handled, cake properties, anticipated capacities and process operating conditions. One may then select the preferred operational mode (batch, semibatch or continuous), and choose a particular system on the above considerations and eomomic constraints. 

Many decisions regarding the selection of the operating mode, batch or semicon-tinuous module configurations, size of equipment, and operating conditions need to be made to promote its industrial application. 

In this chapter we have made the jump from molecular models to reactor models. These were developed for various operation modes, batch, semi-batch, continuous with plug flow, continuous and well mixed and a cascade of continuous well mixed reactors. Each reactor model was based on a combination of mass balances and equations for chemical kinetics. These were all models of ideal reactors therefore the modelling was uncomplicated and quite straightforward. The reactor models are called "ideal" because of the following assumptions ... 

In any case, heat-transfer requirements are largely determined by the operation mode. Batch is the most critical operation because high polymerization rates are achieved due to the high monomer concentration. In semibatch mode, the heat generated can be easily controlled by the monomer feed rate. In these reactors, extra cooling is provided by the cold feed. In continuous mode, the continuous cold feed facilitates the control of the reactor temperature, particularly when the reactor temperature is high. 

Independently of the operation mode (batch, semibatch, or continuous), in well-mixed stirred-tank reactors the properties do not vary significantly with the position in the reactor, and time is the only independent variable. Therefore, the necessary balances for the reactor design may be made at macroscopic level - that is, for the reactor as a whole. 

Great progress was achieved in the past decades regarding the development of mammalian cell culture technology [2,34,98-102]. Nevertheless, the design and layout of cultivation systems and bioreactors have to meet cell-specific demands due to the special characteristics of these cells. Selection of a suitable type of cell culture bioreactor system and/or an appropriate operation mode (batch, fed-batch, or perfusion) is affected by technical, biological, economical, and regulatory considerations. 

Operating mode batch, semibatch, or continuous operation... 

The appropriate operating mode (batch, semibatch, or continuous operation) will depend on the mixing process and the process result desired. Batch and semibatch operations are best suited for processes that require long time scales, greater than a few seconds. 

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