Solve the entire math problem!
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This post was last edited by Fengshan on 2015-6-3 20:13. Hexane and pentane make up 50% (wt%) each in the feed to the distillation column; the purity of pentane at the top of the column is 95% (wt%), while the purity of hexane at the bottom is 96% (wt%). The reflux ratio at the top of the column is 0.6. Questions: 1. For each kg of feed, how many kg are obtained from the top and bottom of the column respectively? 2. What is the ratio of the amount entering the condenser at the top of the tower to the feed rate?
The reflux ratio given for this problem seems useless.
That’s exactly how the question was posed; I don’t know the answer, so I’m bringing it up for discussion.
Using 1 kg of feed, the material balance gives: 1 = D + W, 1*0.5 = D*0.95 + W*0.04. Thus, D = 0.505 kg and W = 0.495 kg. The amount condensed at the top of the tower is V = (R+1)*D = 1.6*0.505 = 0.808 kg. Therefore, V/F = 0.808/1 = 0.808
It’s obviously a question from \"Principles of Chemical Engineering\"
I’ve forgotten all the principles of chemical engineering, but I can use process simulation software to work with it
This post was last edited by ylb913 on 2015-6-15 09:55. The calculation on page 4 is correct; D represents the amount of product taken from the reboiler at the top of the tower, while W represents the amount of product taken from the bottom of the tower. D plus W equals 1 ； Equation D multiplied by 95% plus W multiplied by 4% equals 0.5, which represents the amount of light components in the feed; or Equation D multiplied by 5% plus W multiplied by 96% equals 0.5, which represents the amount of heavy components in the feed. By substituting D=1-W into any of the equations above, the same result is obtained: 0.91W=0.45, so W=0.4945. D=1-0.4945=0.5055. The reflux ratio is the amount of reflux compared to the amount of product obtained from the reflux tank; this value is 0.5055. The amount of reflux is equal to 0.5055*0.6=0.3033, and the amount of product obtained from the top of the tower is 0.5055+0.3033=0.8088