Continuous well-stirred extractor

If fiuid streams with or without solid particles are entering and other streams are exiting the well-stirred separator continuously, we have a continuous stirred tank separator (CSTS), provided that its properties are uniform throughout the separator. Figure 6.4.1(a) illustrates a CSTS which is a crystallizer. The conditions in such a separator are time- and space-invariant However, the intensity of mixing conditions in the separator is such that the fresh feed introduced into the separator is mixed in a time interval which is very short compared to the mean residence time of the fluid elements (and solid particles) in the separator. Figure 6.4.1(b) illustrates a continuous well-stirred extractor... 

The dry calcium malonate is placed in a 3-I. round-bottomed flask with sufficient (750-1000 cc.) alcohol-free ether (Note 3) to make a paste which can be stirred. The flask is surrounded by an ice bath, and the well-stirred salt is treated with 1 cc. of 12 N hydrochloric acid for each gram of salt. After the acid has been added slowly through a dropping funnel, the solution is transferred to a continuous extractor (Note 4) and extracted with ether until no more malonic acid is obtained. The product, as obtained from the undried ether solution by concentration, filtration, and drying in the air, melts at 130° or higher and is sufficiently pure for most purposes. The yield is 415-440 g. (77-82 per cent of the theoretical amount). 

Figure 1 diagrams a continuous stirred-tank extractor and indicates the pertinent design parameters. In a well-stirred, steady-state extractor, the bulk phase concentration of solute is uniform throughout the tank and equal to the constant outlet concentration, C b bulk phase feed enters the extractor at a concentration... 

Models for coalescence frequency show the importance of agitation rate, physicochemical phenomena, and interfacial properties on coalescence. This information is broadly useful for explaining the behavior of stirred vessels, decanters, extractors, and centrifuges, as well as how to prevent coalescence. It is also useful in the determination of which phase will tend to dominate as the continuous phase and in the interpretation of phase inversion phenomena. 

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