Elementary Principles 97

Elementary Principles 97 - 4.63 a. A balance on ith tank...

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4- 56 4.63 a. A balance on i th tank (input = output + consumption) ±± , , ± , ± vC v C k C C V CC k C C A i Ai Ai Bi A i Ai Ai Bi vV v L min mol L mol liter min L note / bg b g b g =+ E ÷= 1 1 τ B balance . By analogy, k C C B i Bi Ai Bi , = + 1 Subtract equations = = −= = −− A CCC C C C C C Bi Ai B i A i i Bi Ai B A ,, , , 11 1 22 0 0 from balances on tank st b. C C Bi Ai B A Bi Ai B A −=−⇒ = + 00 . Substitute in A balance from part (a). k C C C C A i Ai Ai Ai B A , + 10 0 . Collect terms in C Ai 2 , C Ai 1 , C Ai 0 . Ck C kC C C k k C C C Ai AL B A A i AL AL B A A i 2 1 2 1 01 ττ αβγ α βτ γ ++ = + + = = = +−= , , where Solution : C Ai = −+ ββ 2 4 2 (Only + rather than ± : since αγ is negative and the negative solution would yield a negative concentration.) ( x min = 0.50, N = 1), ( x min = 0.80, N = 3), ( x min = 0.90, N = 4), ( x min = 0.95, N = 6), ( x min = 0.99, N = 9), ( x min = 0.999, N = 13). As x min 1, the required number of tanks and hence the process cost becomes infinite. d. (i) k increases N decreases (faster reaction fewer tanks) () ± ii increases increases (faster throughput less time spent in reactor
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This note was uploaded on 02/27/2012 for the course CHEMICAL E 312 taught by Professor Cheung during the Fall '11 term at The University of Akron.

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