What if…(a) Example 13–1. What fraction of the fluid spends nine minutes or longer in the...

What if…

(a) Example 13–1. What fraction of the fluid spends nine minutes or longer in the reactor?

(b) The combinations of ideal reactors are used to model the following real reactors, given

Suggest a model for each figure.

(c) Example 13–3. How would the E(t) change if τP as reduced by 50% and τs was increased by 50%?

(d) Example 13–4. For 75% conversion, what are the relative sizes of the CSTR, PFR, and LFR?

(e) Example 13–5. How does the mean conversion compare with the conversion calculated with the same tm applied to an ideal PFR and CSTR? Can you give examples of E(t) where this calculation would and would not be a good estimate of X?

(f) Example 13–6.> Load the Living Example Problem. How would your results change if T = 40 °C? How would your answer change if the reaction was pseudo first order with kCA0 = 4 x10−3/s? What if the reaction were carried out adiabatically where

(g) Example 13–7. Load the Living Example Problem. How does the Xseg and XMM compare with the conversion calculated for a PFR and a CSTR at the mean residence time?

(h) Example 13–8. Load the Living Example Problem. How would your results change if the reaction was pseudo first order with k1 = CAOk = 0.08 min−1? If the reaction was third order with kC2A0 = 0.08 min−1? If the reaction was half order with kCA0 = 0.08 min−1? Describe any trends.

(i) Example 13–9. Load the Living Example Problem. If the activation energies in cal/mol are E1 = 5,000, E2 = 1,000, and E3 = 9,000, how would the selectivities and conversion of A change as the temperature was raised or lowered around 350 K?

(j) Heat Effects. Redo Living Example Problems 13–7 and 13–8 for the case when the reaction is carried out adiabatically with

(1) Exothermic reaction with

with k given at 320 K and E = 10,000 cal/mol.

(2) Endothermic reaction with

and E = 45 kJ/mol. How will your answers change?(k) you were asked to compare the results from

Example 13–9 for the asymmetric and bimodal distributions in Tables El 3–9.2 and E13-9.4. What similarities and differences do you observe? What generalizations can you make?

(1) Repeat (h) above using the RTD in Polymath program E13-8 to predict and compare conversions predicted by the segregation model.

(m) the reaction in Example 13–5 was half or der with kC1/2A0 = 0.08 mm−1! How would your answers change? Hint: Modify the Living Example 13–8 program.

(n) you were asked to vary the specific reaction rates k1 and k2 in the series reaction  C given on the Solved Problems CD-ROM? What would you find?

(o) you were asked to vary the isothermal temperature in Example 13–9 from 300 K, at which the rate constants are given, up to a temperature of 500 K? The activation energies in cal/mol are E1 = 5000, E2 = 7000, and E3 = 9000. How would the selectivity change for each RTD curve?

(p) the reaction in Example 13–7 were carried out adiabatically with the same parameters as those in Equation [P13-2(j).l]? How would your answers change?

(q) If the reaction in Examples 13–8 and 13–5 were endothermic and carried out adiabatically with

how would your answers change? What generalizations can you make about the effect of temperature on the results (e.g., conversion) predicted from the RTD?

(r) If the reaction in Example 8–12 were carried out in the reactor described by the RTD in Example 13–9 with the exception that RTD is in seconds rather than minutes (i.e., tm = 1.26 s), how would your answers change?