Chapter 19 : The Packed Bed Catalytic Reactor

Example 19.1 page no : 438

In [4]:
%matplotlib inline

from matplotlib.pyplot import *

# Variables
Cp = 40.                    #J/mol.k
Hr = 80000.                 #J/mol.k
FAo = 100.                  #mol/s
nA = 1.
nB = 7.
n = nA + nB
T1 = 300.                   #k
T2 = 600.                   #k
T3 = 800.                   #k

# Calculations
m = Cp/Hr;
XA = [0.8,0.78,0.7,0.66,0.5,0.26,0.1,0];
inv_rA = [20,10,5,4.4,5,10,20,33];


plot(XA,inv_rA)
xlabel("Xa")
ylabel("1/8 X 1/-rA")

print ('From the plot we can say that a recycle reactor should be used')
W = FAo*38.4
R = 1.;
Q1 = n*FAo*Cp*(T2-T1);
Q2 = n*FAo*Cp*(T1-T3);

# Results
print " The weight of catalyst needed is %.f kg"%(W)
print " The Recycle Ratio is %.f"%(R)
print " The heat exchange for feed is %.f MW"%(Q1/10**6)
print " The heat excahnge for the product is %.f MW"%(Q2/10**6)
show()

Populating the interactive namespace from numpy and matplotlib
From the plot we can say that a recycle reactor should be used
 The weight of catalyst needed is 3840 kg
 The Recycle Ratio is 1
 The heat exchange for feed is 10 MW
 The heat excahnge for the product is -16 MW

WARNING: pylab import has clobbered these variables: ['draw_if_interactive']
`%pylab --no-import-all` prevents importing * from pylab and numpy

Example 19.2 page no : 440

In [3]:
import math 
from matplotlib.pyplot import *

# Variables
Cp = 40.
Hr = 80000.
m = Cp/Hr;
FAo = 100.              #mol/s
print ('We should use a mixed flow reactor operating at optimum')

# Calculations and Results
XA = [0.85,0.785,0.715,0.66,0.58,0.46];
inv_rAopt = [20,10,5,3.6,2,1];
plot(XA,inv_rAopt)

area1 = 0.66*3.6;
area2 = (0.85-0.66)*20;
W1 = FAo*area1;
W2 = FAo*area2;
print " The weight of catalyst needed for 1st bed is %.1f kg"%(W1)
print " The weight of catalyst needed for 2ndbed is %.1f kg"%(W2)

#Heat exchange
#For the first reactor
Q = (820-300)*Cp+0.66*(-Hr);

#For 100 mol/s
Q1 =  FAo*Q/10**6;#MW
print " The amount of heat exchanged for 1st reactor is %.2f MW"%(Q1)

#For 2nd reactor
#To go from XA = 0.66 at 820 k to XA = 0.85 at 750 k
Q2 = FAo*((750-820)*Cp+(0.85-0.66)*(-Hr));
Q2 = Q2/10**6;
print " The amount of heat exchanged for 2nd reactor is %.2f MW"%(Q2)

#For the exchanger needed to cool the exit stream from 750 k to 300 k
Q3 = FAo*Cp*(300. - 750);
Q3 = Q3/10**6;#MW
print " The amount of heat exchanged for exchanger is %.2f MW"%(Q3)

show()

We should use a mixed flow reactor operating at optimum
 The weight of catalyst needed for 1st bed is 237.6 kg
 The weight of catalyst needed for 2ndbed is 380.0 kg
 The amount of heat exchanged for 1st reactor is -3.20 MW
 The amount of heat exchanged for 2nd reactor is -1.80 MW
 The amount of heat exchanged for exchanger is -1.80 MW
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