We want to solve Example 13-6 with a multicomponent computer program similar to absorption and stripping programs. Set up the tridiagonal matrix for the mass balances assuming there are six stages in the column and exit raffinate stream concentration is unknown. Develop the values for A, B, C, and D for only the acetic acid matrix using K values determined from Table 13-7. Do not invert the matrix.

Example13-6

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A solution of acetic acid (A) in water (D) is to be extracted using isopropyl ether as solvent (S). 1000 kg/h of a feed containing 35 wt% acetic acid and 65 wt% water is fed to a countercurrent extractor. Solvent is from a solvent recovery plant and is essentially pure isopropyl ether. Inlet solvent flow rate is 1475 kg/h. Exiting raffinate stream should contain 10 wt% acetic acid. Operation is at 20C and 1 atm. Find outlet concentrations and number of equilibrium stages required. Equilibrium data are in Table 13-7 (Treybal, 1980). TABLE 13-7. Equilibrium data for water-acetic acid-isopropyl ether at 20C and 1 atm Water Layer, weight % Isopropyl Ether Layer, weight % Acetic Acid Water Isopropyl Ether Acetic Acid Water Isopropyl Ether XD XS YA YD ys 0.69 98.1 1.2 0.18 0.5 99.3 1.41 97.1 1.5 0.37 0.7 98.9 2.89 95.5 1.6 0.79 0.8 98.4 6.42 91.7 1.9 1.93 1.0 97.1 13.30 84.4 2.3 4.82 1.9 93.3 25.50 71.1 3.4 11.40 3.9 84.7 36.70 58.9 4.4 21.60 6.9 71.5 44.30 45.1 10.6 31.10 10.8 58.1 46.40 37.1 16.5 36.20 15.1 48.7