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Unformatted text preview: Chemical Engineering 142 Homework Set #2 100 points total Due Wednesday, February 3, 2010 Problem 1 (20 points) Consider the reactor scheme below, A liquid phase reaction, A + 2B C, occurs at steady-state according to the following rate expression: k = 0.6 mol L-1 min-1 K = 1 L mol-1 The molar flow rate of B must be less than or equal to 1 mol min-1 to avoid unwanted side reactions. A side-stream (flow rate = 0.5 L min-1 ) containing B is added between the two reactors to increase the overall conversion of A. Reactors 1 and 2 are isothermal PFRs with volumes of 2 and 0.5 L, respectively. The inlet volumetric flow rate to reactor 1 is 2 L min-1 and remains constant during the reaction with inlet molar flow rates of 1 mol min-1 B and 1 mol min-1 A. (a) What molar flow rate of reactant B in the side-stream will maximize the conversion of A without producing side reactions? (b) What is the maximum overall conversion of A for the molar flow rate of B determined in part (a)? Make-up Stream Reactor 1 Reactor 2 Problem 2 (20 Points) In biological reactors, the growth rate is autocatalytic in that the more cells that you have, the greater the growth rate, cells + nutrients more cells + product The cell growth rate, r g , and the rate of nutrients consumption, r s , are directly proportional to the concentration of cells for a given set of conditions. A Levenspiel plot for this system is given below. Units of -1/rbelow....
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