Load the following Polymath/MATLAB/COMSOL programs from theCD-ROM where appropriate:(a) Ex...

Load the following Polymath/MATLAB/COMSOL programs from theCD-ROM where appropriate:

(a) Example 8–1. How would this example change if a CSTR were used instead of a PFR?

(b) Example 8–2. What would the heat of reaction be if 50% inerts (e.g., helium) were added to the system? What would be the % error if the ΔCP term were neglected?

(c) Example 8–3. What if the butane reaction were carried out in a 0.8-m3 PFR that can be pressurized to very high pressures? What inlet temperature would you recommend? Is there an optimum temperature? How would your answer change for a 2-m3 CSTR?

(d) Example 8–4. (I) How would the answers change if the reactor were in a counter current exchanger where the coolant temperature was not constant along the length of the reactor? The mass flow rate and heat capacity of the coolant are 50 kg/h and 75 kJ/kg/K, respectively, and the entering coolant temperature is 310 K. Vary the coolant rate, >ii , to make a plot of X versus m . (2) Repeat (1) but change the parameters Kc, E, 1,000

(e) Example 8–5. (1) How would your answer change if the coolant flow was counter current? (2) Make a plot of conversion as a function of FA0 for each of the three cases. (3) Make a plot of conversion as a function of coolant rate and coolant temperature. (4) Make a plot of the exit conversion and temperature as a function of reactor diameter but for the same total volume.

(f) Example 8–6. How would the result change if the reaction were second order and reversible 2A 2B with Kc remaining the same?

(g) Example 8–7. How would your answers change if the heal of reaction were three times that given in the problem statement?

(h) Example 8–8. Describe how your answers would change if the molar flow rate of methanol were increased by a factor of 4.

(i) Example 8–9. Other data show ΔH°Rx = −38,700 Btu/lbmol and CpA = 29 Btu/lbmol/°F. How would these values change your results? Make a plot of conversion as a function of heat exchanger area. [02].

(j) Example 8–10. How would your results change if there is (1) a pressure drop with a = 1.05 dm−3, (2) Reaction (1) is reversible with Kc = 10 at 450 K. (3) How would the selectivity change if Ua is increased? Decreased?

(k) Example 8–11. (1) How would the results (e.g., Sb/c) change if the UA term were varied (7003 • s ■ K)? (2) If t were varied [(0.1 > t> 0.00001 min)]?

(1) CD Example R8.4-1. SO2 oxidation. How would your results change if (1) the catalyst particle diameter were cut in half? (2) the pressure were doubled? At what particle size does pressure drop become important for the same catalyst weight assuming the porosity doesn’t change? (3) you vary the initial temperature and the coolant temperature? Write a paragraph describing what you find

(m) Example T8-3. Load the Polymath problem from the CD-ROM for this exothermic reversible reaction with a variable coolant temperature. The elementary reaction

has the following parameter values for the base case.

Vary the following parameters and write a paragraph describing the trends you find for each parameter variation and why they work the way they do. Use the base case for parameters not varied. Hint: See Selftests and Workbook in the Summary Notes on the CD-ROM.

*Note: The program gives  = 1.0. Therefore, when you vary  you will need to account for the corresponding increase or decrease of CA0 because the total concentration, Cm, is constant

(7) Repeat (f) for counter current coolant flow.

(8) Determine the conversion in a 5,000 kg fluidized CSTR where UA = 500 cal/s K with Ta = 320 K and pb = 2 kg/m3.

Repeat (a), (b), and (d) if the reaction were endothermic with Kc = 0.01 at 303 K and ΔH°Rx = +20 kcal/mol.

(n) Example 8–12. Instructions: If you have not installed COMSOL 3.2 ECRE, load the COMSOL 3.2 ECRE CD-ROM and follow the installation instructions.

Double-click on the COMSOL 3.2 ECRE icon on your desktop. In the Model Navigator, select model denoted “4-Non-Isothermal Reactor II” and press “Documentation”. This will open your web browser and display (he documentation of this specific model. You can also review the detailed documentation for the models listed on the left-hand side in the web browser window. Click on Chapter 2 radial effects in the left hand margin. This section gives an overview of all the model equations. Next, click on non-isothermal reactor with non-isothermal cooling jacket and follow the step by step instructions and screen shots. Select the Model Navigator and press “OK” to open the model.

(1) Why is the concentration of A near the wall lower than the concentration near the center? (2) Where in the reactor do you find the maximum and minimum reaction rates? Why? Instructions: Click the “Plot Parameters” button and select the “Surface” tab. Type “—rA” (replace “cA”) in the “Expression” edit field to plot the absolute rate of consumption of’A (moles m−3 s−l). (3) Increase the activation energy of the reaction by 5%. How do the concentration profiles change? Decrease. Instructions: Select the “Constants” menu item in the “Options” menu. Multiply the value of “E” in the constants list by 1.05 (just type “*1.05” behind the existing value to increase or multiply by 0.95 to decrease). Press “Apply”. Press the “Restart” button in the main toolbar (equal sign with an arrow on top). (4) Change the activation energy back to the original value. Instructions: Remove the factor “0.95” in the constant list and press “Apply”. (5) Increase the thermal conductivity, ke, by a factor of 10 and explain how this change affects the temperature profiles. At what radial position do you find the highest conversion? Instructions: Multiply the value of “ke” in the constants lists by 10. Press “Apply”. Press “Restart”. (6) Increase the coolant flow rate by a factor of 10 and explain how this change affects the conversion. (7) In two or three sentences, describe your findings when you varied the parameters (for all parts). (8) What would be your recommendation to maximize the average outlet conversion? (9) Review Figure E8-12.2 and explain why the temperature profile goes through a maximum and why the conversion profile goes through a maximum and a minimum. (10) See other problems in the web module.

(o) Example R8.2-1 Runaway Reactions. Load the Living Example Problem on runaway trajectories. Vary some of the parameters, such as P0 and T0 along with the activation energy and heat of reaction. Write a paragraph describing what you found and what generalizations you can make.