Point permeate withdrawal

Differential Permeation with Point Permeate Withdrawal... 

Figure 5.1 Differential permeation with point permeate withdrawal.

Differential Permeation ivith Point Permeate Withdrawal i 175... 

By analogy with Section 5.6 of Chapter 5, for differential permeation with point permeate withdrawal, the equation to be integrated is... 

Table A5.1 Excel Spreadsheet Designators and Formulas for Differential Permeation with Point Permeate Withdrawal Calculations...

Following this, more rigorous derivations for differential permeation are pursued. That is, permeation is viewed as a continuum rather than an operation in discrete stages or cells. In the first case to be considered, there is continuous point permeate withdrawal in another case, the more general case of permeate flow is analyzed, both concurrently and coun-tercurrently. 

The depletion by membrane permeation of C02 in blood introduces cause for concern. This affects the evaluation of PBot and also shifts the position of the 02 dissociation curve. The correction for this effect requires the continuous evaluation of the acid—base status of the blood sample. Using an initial reference point obtained from a separate pH measurement and Pco2> the variation in pH during the withdrawal process can be determined with incremental measurements of PBc02 ( ) ... 

Figure 1.8 Point withdrawal of permeate. (Source Bravo et al. ...

Of special consideration is the investigation of the cell as a continuum, first with point withdrawal of the permeate, then in both concurrent and countercurrent flow for the permeate and the reject phases. For this treatment, differential permeation is the mode of attack. The differential... 

In matter of fact, the feedstream may be prorated into any of the cells, at will, but would involve stage-to-stage or cell-to-cell calculations. However, in distillation, the rule of thumb is that multifeed locations are used only if there are several feedstreams with different compositions. Each feedstream is introduced at the point or location that most likely approximates its own composition. This is a facet of so-called optimum feed location, where the overall separation is made more efficient. The same sort of remarks can be made for intermediate permeate or reject withdrawal, if a stream product of a particular composition is desired.)... 

A membrane separation is to be conducted with a continuous withdrawal of the permeate. At each linear point along the membrane during the separation, the reject phase composition is governed by a bubble-point type determination, starting with the initial feed composition. 

For the point withdrawal of the permeate as a bulk phase, the membrane or interfacial area can be determined after the fact that is, it is not necessary to include A as a variable in establishing the a priori relationships among y, x, and L or V. 

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