Additional Homework Problems

P8-29_B

Exothermic reversible reaction with a variable coolant temperature. The elementary reaction

A + B 2 C

is carried out in a PBR that has a heat exchanger surrounding the reactor. The feed is equal molar in A and b with F_A0 = 5 mol/s. The coolant surrounding the PBR flow in the same direction as the reactants. The feed enters at a temperature of 330 K. Plot X, Xe and T as a function of catalyst weight up to W = 4500 kg, for the base case given below.

Additional Information (base case)
E = 25 kcal/mol

C_PA = C_PB = C_PC = 20 cal/mol/K

H_RX = -20 kcal/mol

C_PI = 40 cal/mol/K

k = 0.004 dm⁶/(kg s) at 310 K

Ua/_B = 0.5 cal/(kg s K)

K_C = 1000 at 303 K

T_a = 320 K

= 0.002 /kg

m_C = 1000 g/s

F_ao = 5 mol/s

C_Pmc = 18 cal/g/K

C_To = 0.3 mol/dm³

_I = 1

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.

1. F_A0     1 F_A0 8 mol/s
   
   
2. _I 0.5 _I 4
   
   
3. Ua/_B 0.1 Ua/_B 0.8 cal/(kg s K)
   
   
4. T₀     310 K T₀ 350 K
   
   
5. T_a     300 K T_a 340 K
   
   
6. m_C     1 m_C 1000 g/s [ T₀ = 350 , Ua/_B = 0.5, T_a = 320, F_A0 = 5, _I = 1]
   
   
7. Determine the conversion in a 5000 kg fluidized CSTR where UA/_B = 500 cal/(kg s K)
   
   
8. If the reaction were endothermic with K_C = 0.01 at 303 and H_RX = +20 kcal/mol

[3rd Ed. P8-15]