Group methods Edmister method

Edmister Group Method Exact Method Edmister Group Method Exact Solution... 

The Kremser approximation gives product distributions that deviate considerably from the exact solution, but the Edmister group method is in reasonably good agreement with the exact results. However, terminal stage temperatures of T, = 100.4°F (38.0°C) and Te = 163.3°F (72.9°C) predicted by the Edmister group method are in poor agreement with values of T = 150.8°F (66.0°C) and Tt = 143.7 (62.1 C) from an exact solution. 

The Edmister group method can now be employed to refine the estimates of I,. From (12-74) through (12-76)... 

Edmister applied the group method to complex separators where cascades are coupled to condensers, reboilers, and/or other cascades. Some of the possible combinations, as shown in Fig. 12.24, are fractionators (distillation columns), reboiled strippers, reboiled absorbers, and refluxed inert gas strippers. In Fig. 12.24, five separation zones are delineated (1) partial condensation, (2) absorption cascade, (3) feed stage flash, (4) stripping cascade, and (5) partial reboiling. 

Except in the vicinity of the feed stage, the results from the Edmister group method compare quite well with the exact solution. 

Kremser originated the group method. He derived overall species material balances for a multistage countercurrent absorber. Subsequent articles by Souders and Brown, Horton and Franklin, and Edmister improved the method. The treatment presented here is similar to that of Edmister for general application to vapor-liquid separation operations. Another treatment by Smith and Brinkley emphasizes liquid-liquid separations. 

Complex Countercurrent Cascades—Edmister Group Method 481... 

Use the Edmister group method to determine the compositions of the distillate and bottoms for the distillation operation below. 

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