Additional Homework Problems

P8-32_B

The elementary irreversible exothermic gas phase reaction

A 2B

is carried out in a packed bed reactor. There is pressure drop in the reactor and the pressure-drop coefficient is 0.007 kg^-1. Pure A enters the reactor at a flow rate of 5 mol/s, at a concentration of 0.25 mol/dm³, a temperature of 450 K, and a pressure of 9.22 atm. Heat is removed by a heat exchanger jacketing the reactor. The coolant flow rate in the jacket is sufficient to maintain the ambient temperature of the heat exchanger at 27°C. The term giving the product of the heat-transfer coefficient and an area per unit volume divided by the bulk catalyst density is



The maximum weight of the catalyst that can be packed in this reactor is 50 kg

1. plot the temperature, conversion X, and pressure ratio (y = P/P₀) as a function of catalyst weight.
   
   
2. At what catalyst weight down the reactor does the rate of reaction (-r_A) reach its maximum value?
   
   
3. At what catalyst weight down the reactor does the temperature reach its maximum value?
   
   
4. What happens when the heat-transfer coefficient is doubled? What happens if the heat coefficient is halved? Discuss your observations on the effects on reactor performance (i.e., conversion, temperature, and pressure drop).

[3rd Ed. P8-12]