Kremser Method

Example 2 Calculation of Kremser Method For the simple absorber specified in Fig. 13-44, a rigorous calculation procedure as described below gives results in Table 13-9. Values of were computed from component-product flow rates, and corresponding effective absorption and stripping factors were obtained by iterative calculations in using Eqs. (13-40) and (13-41) with N = 6. Use the Kremser method to estimate component-product rates if N is doubled to a value of 12. 

Example 2 Calculation of Kremser Method For the simple absorber specified in Fig. 13-35, a rigorous calculation procedure as described below gives the results in Table 13-7. Values of were computed from component... 

Based on preliminary studies, it was determined that a 10-tray column is appropriate for an absorption operation. The overall tray efficiency is estimated at 60%. For the indicated feed gas and absorbent, determine the expected flow rates and compositions of the products using the Kremser method. 

Solve Example 12.8 by the Kremser method, but for an absorbent flow rate of 330 Ibmole/hr and three theoretical stages. Compare your results to the Kremser results of Example 12.8 and discuss the effect of trading stages for absorbent flow. 

The separation factor in the Kremser method is an effective absorption factor, for absorption and a stripping factor, 5, for stripping, rather than a relative volatility as in the FUG method for distillation. These two factors, which are different for each component, are defined by ... 

The total molar liquid rate down the tower, L, the total molar vapor rate up the tower, V, and the K-value all vary from the top stage to the bottom stage of the tower. However, sufficiently good estimates by the Kremser method can be achieved by using average values based on the flow rates and temperatures of the two streams entering the tower. 

For simple absorbers and strippers, the Kremser method described in Section 14.3 can be used to obtain an initial approximation to the number of equilibrium stages and the flow rate of the absorbent or stripping agent. Then, with the rigorous method, the latter can be varied to achieve the desired separation of the key component for a fixed number of stages. 

In this chapter, we considered what extraction is used for, developed McCabe-Thiele and Kremser methods for immiscible extraction, and explored methods for ternary partially miscible extraction systems. At the end of this chapter, you should be able to satisfy the following objectives ... 

Apply the McCabe-Thiele and Kremser methods to immiscible extraction... 

The McCabe-Thiele and Kremser methods can be applied to analyze other separation processes. Adsorption, chromatography, and ion exchange are occasionally operated in counter current columns. In some situations crystallization can be analyzed as an equilibrium stage separatiom The application of the McCabe-Thiele procedure in these cases is explored by Wankat (1990). 

The McCabe-Thiele and Kremser methods have also been applied to analyze less common separation methods. A modification of the McCabe-Thiele method has been applied to parametric punping, which is a cyclic adsorption or ion exchange process iGrevillot and Tondeur. 19771. A similar modification can... 

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