Additional Homework Problems

P12-31B

You are an engineer who is to design a CSTR for the elementary consecutive gas-phase reactions



The feed conditions and desired product specifications are known, together with the temperature of the heating medium. It is your job to design the reactor, that is, to specify the reactor volume and the area of the heating coil inside the reactor.

  1. Calculate the desired operating temperature inside the reactor. (ANS: 269°F)

  2. Calculate the volume of the reactor. (ANS: 6.58 ft3)

  3. Calculate the area of the heating coil. (ANS: 18.1 ft2)

  4. Find a set of conditions that will give multiple steady states if reaction 1 is exothermic rather than endothermic. How many steady states can you find? (ANS: 5) Make a plot of G(T) vs. R(T) and of TS vs. T0.
Additional Information
Product:
       The ratio CB/CC is equal to 10.
       50% of A in the feed is converted.


Feed:
       The feed is gas-phase and pure A.
       The molar flow rate is 0.05 lb mol/s.
       The volumetric flow rate is 7.85 ft3/s.
       The temperature is 400°F.
       The pressure in the reactor is 4 atm.


Heat Capacities:
       Cp's of A, B, and C are all 25 Btu/(lb mol °F)


Heat transfer:
       The heating medium is saturated high-pressure steam at 350°F.
       The overall heat-transfer coefficient between the heating medium and the reaction mixture is 400 Btu/(h ft2 °F).

[3rd Ed. P8-28]