Extraction contacting devices

Table 2.5 Order of preference for extraction contacting devices...

In the extraction process, the LPG from the prewash tower enters the bottom of an extractor column. The extractor is a liquid/liquid contactor in which the LPG is counter-currently contacted by a caustic solution. Another option is the use of a fiber film contacting device. The mercaptans dissolve in the caustic (Equation 1-14). The treated LPG leaves the top of the extractor and goes on to a settler, where entrained caustic is separated. 

Systems that exhibit behavior of the type illustrated in Fig. 4 cannot be purified in a single crystallization stage. They represent situations in which multiple stages or continuous-contacting devices may be useful. The principles of such operations are analogous to those of other countercurrent contacting operations—for example, distillation, absorption, and extraction. 

FIGURE 8 J-1 Comparisons of the operating characteristics of several contacting devices for the separation of copper front nickel and zinc by extraction from ammonia (pH 8) solution with Kelex. (o) Comparison of specific throughput at flooding, (b) Comparison of coppar extraction elficiency. (c) Compariaou of Cu-Zn selectivity. [Pg.493]

Test transistors allow for process monitoring and straightforward extraction of device performance. Several material parameters (such as the dielectric capacitance and the gate source/drain misalignment) can also be measured directly from a transistor. Transistors with a range of channel lengths should be included to allow for contact parameter extraction. A detailed layout is shown in Fig. C.6. 

A summary of the advantages and disadvantages of the contacting devices used in extraction, as well as a preference ordering, is given in Tables 2.4 and 2.5, respectively. 

As is apparent from Section 7.6, a wide variety of liquid-liquid contacting devices exist. Consequmtly, the design engineer is faced with the problem of selecting the most appropriate device for a particular applicalion. In addition, it is usually necessary to estimate an oveiali extraction efficiency for the operation. Of course, it is preferable to obtain experimental data for a given application. However, in the absence of such data, it is often possible to obtain picliminaiy efficiency estimates fiom correlations which ate available in the literature. 

This paper summarises this development work which has resulted in a comprehensive range of extraction resistant flexible PVC compounds and discusses application areas ranging from stomach feeding tubes and nutritional fluid bags to blood contact devices such as dialysis sets and blood bags. 

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