Absorber Edmister

This method [18] is well suited to handling the details of a complicated problem, yet utilizing the concept of average absorption and stripping factors. It also allows for the presence of solute components in the solvent and the loss of lean oil into the off gas. Reference 18 presents more details than are included here. Reference 18 is Edmister s original publication of the basic method for absorbers and strippers. Reference 18 also generates the... 

Edmister s effective absorption factor Outside surface area of absorber, ft ... 

Horton and Franklin (1940) used the average absorption factor approach in analyzing a number of absorbers in the petroleum industry. Edmister (1943) extended the Horton and Franklin concept, retaining the Kremser equation form and making use of several empirical factors. He used an effective absorption factor Ae and a modified absorption factor A, given by... 

Hines and Maddox (1985) found that the Edmister method gives a close approximation to observed or rigorously computed concentration gradients in many multicomponent absorbers. 

Another multistage method included in the program is the absorption and stripping factor method of Edmister (25). ASFPH, as it is called, can simulate simple and reboiled absorbers and also fractionators. The method used does not have very good convergence characteristics however, it is of value in studying plant performance data. 

Kremser-Brown-Sherwood Method — No Heat of Absoip-tion, 108 Absorption — Determine Component Absorption in Fixed Tray Tower, 108 Absorption — Determine Number of Trays for Specified Product Absorption, 109 Stripping— Determine Theoretical Trays and Stripping or Gas Rate for a Component Recovery, 110 Stripping — Determine Stripping-Medium Rate for Fixed Recovery, 111 Absorption — Edmister Method, 112 Example 833 Absorption of Hydrocarbons with Lean Oil, 114 Intercooling for Absorbers, 116 Absorption and Stripping Efficiency, 118 Example 834 Determine Number of Trays for Specified Product Absorption, 118 Example 835 Determine Component Absorption in Fixed-Tray Tower, 119 Nomenclature for Part 2, 121... 

FIGURE 13.10 Nomenclature for use of the Edmister method for determining stages in absorbers and strippers. In order to maintain similarity of equations for absorption and stripping, the stages are numbered up from the bottom of the stripper. 

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. 

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. 

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