Question

The following e-mail is in your inbox Problem 4-22 (Level 2) at 8 AM on Monday To: From: U. R. Loehmann I. M. DeBosse L Subject: #9 Expansion Executives at Cauldron Chemical Company are very pleased with the success of our product, L.P. #9. (Cauldron is a very secretive company, so that all of our products have nondescriptive designations; please adhere to this convention in all of your work.) Initially, we produced LP. #9 in a batch reactor on an as- needed basis. Now, the largest batch reactor that Cauldron owns is dedicated to L.P #9 production. In the near future, it will be necessary to produce the product continuously. The reaction is L.P. #8 → L.P. #9 This is a homogeneous reaction that takes place in solution. The reaction is second order in L.P #8. The maximum operating temperature is 150 °C because L.P #8 degrades at higher temperatures. The rate constant at 150 °C is 0.133 1/mol-h. Cauldron has two continuous reactors that are not in use. One is an agitated, 2000-1 reactor that behaves as a CSTR. The second is a 100-1 tubular reactor that behaves as a PFR. Cauldron would like to produce 345 mol of L #9 per hour from a feed that contains 4.0 mol L.P #8A. The fractional conversion of L.P #8 must be 0.95 or higher because of constraints in the downstream product separation system. Skip Tickle, Production Manager for L.P. Products, is in charge of the overall project. He has asked the following questions: 1. How should the CSTR and PFR be configured? (series or parallel? If in series, which reactor first?) 2. what will the final fractional conversion of LP. #8 be for the reactor configuration in Part 1, assuming that the LP. #8 feed rate is 363 mol/h (345 mol L.P #90.95)? Please report your answers to these questions to Skip in a short memo. Attach your calculations to the memo to support your conclusions.

Answer 1

Given data: (L.P #8 is denoted as A and L.P #9 as B for convenience)

1. Homogeneous reaction taking place in a solution (Constant volume reaction system).

2. Reaction is second order in A (So, (-r_A)=kC_A² ; k=0.133 L/mol-h)

3. V_CSTR=2000L ; V_PFR=100L

4. Production rate= F_B=345 mol/hr and C_AO=4mol/L

Part (1) To maximize the conversion of A the reactors should be placed in series. Also, as the reactions with order greater than 1 requires late mixing to keep high reaction rates therefore PFR followed by CSTR is the required arrangement.

Part (2)
hr PFR CSTR V 2000L ㄙ volume uretion syslnm FAD 36 3 1-XAL XA586 (1-Xa) 1 +0 586 90 75 0 133x 41-XA2) 6( 32 う。 1 01 665 5501 cv AAX 스

→ in anuplifaaton we get the fella vina gladnatc eglation Solving thuù equalion 42 = 0.8069