Batch mode

The use of stirred fermenters with automatic control of the culture environment is the most suitable technique to evaluate bacterial or fungal kinetics. Cultures can be operated in discontinuous mode (batch cultures). 

Most industrial bioprocesses are now operated in a batch mode. Batch processing is the method of choice for small-scale production,... 

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 ideal tank reactor is one in which stirring is so efficient that the contents are always uniform in composition and temperature throughout. The simple tank reactor may be operated in a variety of modes batch, semibatch, and continuous flow. These modes are illustrated schematically in Figure 8.1. In the simple batch reactor the fluid elements will all have the same composition, but the composition will be time dependent. The stirred tank reactor may also be... 

The defined scope determines the applicability of developed planning requirements and the planning model limited to the selected attributes. For example, the value chain for commodity production is focused on campaign and continuous production modes batch production is out of the scope that planning requirements and consequently, planning model are not developed for batch production problems. 

This section presents a classification of conversion concepts (read section 0), described in the literature on PBC, for example, fuel-bed mode (batch or continuous) and fuel-bed configuration (cocurrent, countercurrent, crosscurrent). Some new conversion concepts, namely fuel-bed movement (fixed, moving and mixed) and fuel-bed composition (homogeneous, heterogeneous), are introduced by these authors, which makes this an extended classification compared with earlier classifications in literature [8,9,10,11], The classification is made in the context of the three-step model. The three-step model, see Figure 14 below, is a system theory, which places the theory of thermochemical conversion of solid fuels into the context of PBC. 

The classification is based on the different conversion concepts cited in the literature, such as fuel-bed mode (batch and continuous), fuel-bed configuration (cocurrent, countercurrent, and crosscurrent), and some new concepts presented by the author, such as fuel-bed movement (fixed, moving, and mixed) and fuel-bed composition (homogeneous and heterogeneuos). The classification resulted in 18 types of updraft conversion systems, according to Figure 32. Some of them are more or less hypothetical, while others are found in practice, see section B 3.4 below. 

According to the three-step model, proposed by the authors, a PBCS can be divided into three subsystems, namely a conversion system, combustion system, and boiler system. It is in the conversion system that the thermochemical conversion of the solid fuel takes place. The conversion system can be designed according to several conversion concepts. The conversion concept can be classified with respect to fuel-bed mode (batch and continuous), fuel-bed configuration (countercurrent, cocurrent and crosscurrent), fuel-bed composition (homogeneous and heterogeneous), and fuel-bed movement (fixed, moving and mixed). 

A significant improvement in the conduction of this reaction was reported under microflow conditions in comparison with batch mode. Batch conditions involved a reaction time of 60 h at room temperature to afford the final product in a 62% yield. Under optimized microreactor conditions, the online HPLC-determined yield was 91 % in a 60 min reaction time (Scheme 2). Note that the microreactor setup allowed the reaction temperature to be higher than the atmospheric boiling point of the solvent. 

Suspension systems can be operated in different modes batch, fed-batch, chemostat, and perfusion (Fig. 1). These operation modes differ basically in the way nutrient supply and metabolite removal are accomplished, which in turn determines cell concentration, product titer and volumetric productivity that can be achieved [8]. The intrinsic limitation of batch processes, where cells are exposed to a constantly changing environment, limits full expression of growth and metabolic potentials. This aspect is partially overcome in fed-batch cultures, where a special feeding strategy prolonges the culture and allows an increase in cell concentration to be achieved. In perfusion and chemostat processes nutrients are continuously fed to the bioreactor, while the same amount of spent medium is withdrawn. However, in perfusion cultures the cells are retained within the bioreactor, as opposed to continuous-flow culture (chemostat), which washes cells out with the withdrawn medium [9]. 

The bioreactor operation mode is normally defined at the outset of process configuration. Insect cells have been cultured in almost all known cultivation modes batch [10], repeated-batch [70], perfusion [71-74], fed-batch [75, 76], semi-continuous [77,78] and continuous [79]. In spite of this multitude of different strategies, the batch or, eventually, fed-batch mode is normally preferred due to the lytic infection cycle of the baculovirus. 

If the size of the production unit requires higher radiant power than can be provided, for technical reasons, by one lamp, clusters of light sources may be installed, which, consequently will alter the diameter or the height of the inner core of, for example, an annular photochemical reactor. However, following the check list of concepts (vide supra), optimal reaction conditions will in most cases limit the size of the photochemical reactor, and the planned rate of production may require several reactor units installed in a parallel mode (batch process) or in series (continuous process). 

The benzoic acid was quantitatively coupled within 5 min via its cesium salt by using a dedicated multi-mode batch reactor, carried out in standard glassware under atmospheric reflux conditions. In a more extended study, various substituted carboxylic acids (Fig. 7.7) were coupled to chlorinated Wang resin, employing an identical reaction protocol. In a majority of cases, the microwave-mediated conversion reached at least 85% after 3-15 min. These microwave conditions represented a significant rate enhancement, in contrast to the conventional protocol, which took 24-48 h. The microwave protocol has additional benefits in comparison to the conventional method, as the amounts of acid and base equivalents can be reduced and potassium iodide as an additive can be eliminated from the reaction mixture27. 

The next step is the preparation of mRNA. Cell-free translation of proteins can be achieved mainly by three different modes—batch (11,12), bilayer (16), and continous-flow cell-free (18). Appropriate volumes of transcription products can be produced depending on the mode of translation. 

Wilson and coworkers described a custom-made flow-reactor for the Bio-tage Emrys Synthesizer single-mode batch reactor (Fig. 21) that was fitted with a glass-coiled flow cell [67]. The flow cell was inserted into the cavity from the bottom of the instrument and the system was operated either under... 

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 ... 

Centrifuges can function in batch-mode and continuous mode. Batch-mode works well for laboratory-scale processes, whereas continuousmode can handle larger volumes and is thus... 

Most of the single-mode reactors commercially available have been designed for small to medium scale reactions (250 L-120 mL). Single mode and multi-mode batch reactors that allow for microwave-assisted synthesis up to 500 mL have been recently introduced. Importantly, reactions optimized in smaller cavities can be directly reproduced in these larger reactors. 

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. 

Industrial fluid-bed drying The first major distinction between fluid-bed types is the choice of mode batch or continuous. 

Commercial industrial processes can be operated in a either batch or a continuous mode. Batch processes are suitable for small plants, while for larger plants (>100 000 ty ) continuous process tend to be more economical. In the ESTERFIP batch process (IFF license), transesterification occurs in a single stirred-tank reactor. Continuous transesterification processes include the Ballestra, Connemann CD and... 

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