Batch processes single stage

Reaction times of fermentation range from a few hours to several days. Batch processes are common, but continuous stirred tanks also are used either singly or in stages. A continuous stirred tank reactor (CSTR) also is called a chemostat. Figure 8.4 is a schematic of a fermentor with representative dimensions from the literature. 

The simplest example of batch distillation is a single stage, differential distillation, starting with a still pot, initially full, heated at a constant rate. In this process the vapour formed on boiling the liquid is removed at once from the system. Since this vapour is richer in the more volatile component than the liquid, it follows that the liquid remaining becomes steadily weaker in this component, with the result that the composition of the product progressively alters. Thus, whilst the vapour formed over a short period is in equilibrium with the liquid, the total vapour formed is not in equilibrium with the residual liquid. At the end of the process the liquid which has not been vaporised is removed as the bottom product. The analysis of this process was first proposed by Rayleigh(24). 

In the single-stage batch process illustrated in Figure 13.1, the solvent and solution are mixed together and then allowed to separate into the two phases—the extract E containing the required solute in the added solvent and the raffinate R, the weaker solution with some associated solvent. With this simple arrangement mixing and separation occur in the same vessel. 

Assess results Several methods can be applied to minimize the ozone consumption in combined processes of ozonation and biodegradation. For example, the different operational behavior of batch and continuous-flow systems, with the resulting differences in oxidation products, etc. has to be considered, as well as the fact that multi-stage systems for each treatment process may be of advantage over single stage systems. 

Commercial PVF is manufactured by a single stage batch process in acetic acid. The ratio of vinyl acetate and vinyl alcohol components in the acetal product is controlled by the ratio of acetic acid, water, and formaldehyde used. 

Plant requirements. Is it a single stage, multi stage batch, continuous process or any combination of these Will it use the existing plant or is a new plant required If it is the latter, chemical engineers and a design team will be involved. 

Establish the separation capability of a single-stage (differential) batch still processing a mixture of two compounds having a relative volatility of 4.0. At the start of the batch separation, there are 600 mol of the more-volatile compound A and 400 mol of compound B in the kettle. When the remaining charge in the kettle is 80 percent B, how much total material has been boiled off, and what is the composition of the accumulated distillate ... 

In some cases, polymers may be compounded from simpler starting compounds formed with two or more of the raw materials. These are identified as master batches and are often prepared when bulk addition to a single stage process would cause them to separate or to alter the bulk polymer properties during mixing to the point where mixing would be inefficient. 

For a single-stage batch process or a continuous extraction process that achieves one theoretical stage, the solute reduction factor is given... 

Solar water heating system for single stage preparation in a kier and pad-batch systems with a process cost savging is possible [28,29]. Solar heat may be utilised to the maximum extent for drying the fabric to reduce consumption of fuel. 

Fig. 11. Single-stage fed-batch SSF process of pretreated corn fiber using Saccharomyces 1400 (pLNH33) [121]... 

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