5 - Reversible Reactions, Membrane reactors, and pressure drop

5 - Reversible Reactions, Membrane reactors, and pressure drop

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Unformatted text preview: CHE4473 Kinetics Spring 2015 Homework N°5: Reversible reactions, membrane reactors and pressure drop Due Tuesday FEB 10th 2015 1. The gas-­‐phase irreversible and first-­‐order reaction Aè 3B is carried out in a PFR, where the feed is equal molar of A and inerts. The conversion under these circumstances is 50 %. The exit from the PFR is fed to a CSTR of the same volume as the PFR under the same P and T conditions. What is the conversion exiting the CSTR? You need to solve this problem by two methods (they both should give the same answer) a. As a function of conversion, incorporating the volume expansion parameter (ε). Note: You will not need to know VR, FA0, CA0, v0, or k to solve this part. b. Numerically, as a function of FA, FI, and FB. In this case, you can give any arbitrary numbers to VR, CA0, FA0, and v0 (let’s say all = 1.0), since they will be the same for each reactor to obtain k and then solve for XA at the exit of the CSTR 2. The reaction A + 2B è C, with -­‐ rA = kA CA CB2 and kA = 0.2 Liter2/mol2.min is carried out in the liquid phase in a 500 Liter tank, as shown below. Initially, the tank is partially filled (400 Liters) with a 0.8 M solution of A. At t=0, the feed stream of 8 Liter/min of a solution containing 5M B is turned on, and this feed continues until the reactor is full, at which time the flow is turned off, but the reaction continues. Assume that the liquid density of the reactor content and the feed are the same and remain constant. a. If the reaction is allowed to continue a very long time, what will be the final concentrations of A, B, and C? b. Prior to making calculations, make sketches of your expected appearance of V, CA, CB, and CC versus time. c. Numerically integrate the A, B, and C mole balances and plot concentrations of A, B, and C versus time from t=0 (when the feed of B is turned on) until at least 90 % conversion of B is achieved. At what time is this conversion attained? 3. A reaction is carried out in a packed bed reactor of cross sectional area of 1 m2 that operates at 600 K and an inlet pressure of 120 atm and an outlet pressure of 100 atm, processing 100 Kg/min of gas. The reactor is packed with 3,000 Kg of spherical catalyst pellets of 0.8 cm in diameter, which have a density of 1.3 g/cm3. The gas properties at this temperature are viscosity = 3 x 10-­‐5 Kg/m sec, density = 0.588 Kg/m3. What is the void fraction of this catalyst bed? 4. The first order reaction A è B + 2 C is carried out in the gas phase in a tubular membrane reactor with no pressure drop. The reaction rate constant at 50 C is 10-­‐4 min-­‐1 and the activation energy 85 kJ/mol. Pure A enters the reactor at 10 atm and 127 C at a molar flow rate of 2.5 mol/min, B flows out through the membrane walls of the reactor into an inert carrier gas with a mass transport coefficient kc = 0.08 sec-­‐1. 5. A phenolic compound undergoes a reversible isomerization Aó B over an acidic zeolite catalyst. Under the reaction conditions of this process, A and B are liquid, miscible, and have the same density. The (concentration) reaction equilibrium constant KC is 5.8. A feed of pure A is sent over an isothermal packed-­‐bed reactor (PBR), reaching 55 % conversion. A second identical PBR is placed downstream, directly connected in series with the first reactor. What overall conversion of A is achieved? ...
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  • Spring '14
  • LanceL.Lobban
  • Reaction, CSTR

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