F11_ECH157_Quiz1

# F11_ECH157_Quiz1 - with a feed flow rate F s =0.1 m 3/min a...

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University of California, Davis Department of Chemical Engineering & Materials Science ECH 157 – Process Dynamics and Control Fall 2011 – Quiz # 1 Instructions : This is a 30-minute closed-book quiz. Please print your name on all answer sheets, label the problems clearly and put them in the right order. Read all questions carefully; answer them concisely and neatly. Point values for each problem are based on 10 points total for the quiz. Good Luck ! Problem 1 (4 points) : Consider the reactor-separator process depicted in the figure below. Identify two different control loops from the process diagram. For each control loop, specify the measured variable, the controlled variable and the manipulated variable. Also, indicate if the chosen control loop is a feedback or a feed-forward control loop. Justify your answer!

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Problem 2 (6 points) : The continuous stirred tank reactor (CSTR) shown in the figure below has been operating for a long time
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Unformatted text preview: with a feed flow rate F s =0.1 m 3 /min, a feed concentration C A0s =1.0 kg-mol/m 3 and reactant concentration C As =0.382 kg-mol/ m 3 . The feed flow rate experiences a step increase to 0.2m 3 /min , while all other process parameters remain constant. Answer the following questions: 1. What are the time constant τ and the steady state gain of the process K (include the units)? 2. Determine the dynamic response of the process (i.e., how the reactant concentration responds to the step change in the feed flow rate). Data and assumptions : 1. The reaction rate law is given by: -r A = k C A 0.5 Where the rate constant Is k = 1.0 kg-mol 0.5 /m 1.5 .s. 2. The reactor is maintained at a constant temperature (T=300 K) and is well-mixed. 3. The mass density of the reaction mixture ( ρ =1000 kg/m 3 ) and the reactor volume (V=0.1 m 3 ) are constant....
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F11_ECH157_Quiz1 - with a feed flow rate F s =0.1 m 3/min a...

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