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Unformatted text preview: ndense at just below this temperature, could use a partial condenser with refrigerant R-14 (carbon tetrafluoride), which from Perry's Handbook (p. 12-26, 6th edition) has a saturation pressure of 70 psia at -150oF. Exercise 7.4
Subject: Operating pressure for distillation of an ethylene-ethane mixture Find: Suitable operating pressure. Analysis: Assume that the distillate is nearly pure ethylene, the most volatile of the two components. To use cooling water, the distillate temperature would be approximately 120oF. But the critical temperature of ethylene is 9.7oC or 49.4oF . Therefore could not condense it. The critical pressure of ethylene is 50.5 atm or 742 psia. Using Fig. 7.16, could consider operation at 415 psia because that is safely below the critical pressure (P/Pc = 0.56 and could operate as high as a P/Pc = 0.8). From Perry's Handbook (p. 3-203, 6th edition), at P = 415 psia (28.6 bar), the saturation temperature of ethylene is 258 K or 4.7oF. To condense at just below this temperature could use a partial condenser with refrigerant R-1270 (propylene), which from Perry's Handbook (p. 12-26,...
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