Approximate calculation of material balance for Cumene production process from Benzene and Propylene-based on the Flowsheet: used for the production of 300 tons/day of cumene.
Benzene feed vaporizer:
(*refer process flowsheet)
The stream of mixed feed of benzene and cumene is feed to the vaporizer with 40 oC at 25 atm.
Equipment
|
Benzene feed pump
|
Propylene feed pump
|
Benzene column
|
Benzene feed
| |||||
Benzene fresh feed
|
Propylene -propane
|
Recycle benzene
|
Benzene mixed feed
| ||||||
Mw
|
kmole
|
kg
|
kmole
|
kg
|
kmole
|
kg
|
kmole
|
kg
| |
BENZENE
|
78
|
107.52
|
8387.09
|
114.24
|
8911.28
|
221.77
|
17298.4
| ||
PROPYLENE
|
42
|
112.00
|
4704.29
|
0
| |||||
PROPANE
|
44
|
5.89
|
259.38
|
0
| |||||
CUMENE
|
120
|
2.21
|
266.08
|
2.21
|
266.088
| ||||
DIPB
|
162
|
0
| |||||||
TOTAL
|
8387.09
|
4963.68
|
9177.37
|
17564.5
| |||||
Equipment
|
Reactor
|
Reactor
|
Flash drum top
|
Flash drum bottom
| |||||
Reactor input
|
Reactor output
|
Fuel gas
|
Feed to the benzene column
| ||||||
Mw
|
kmole
|
kg
|
kmole
|
kg
|
kmole
|
kg
|
kmole
|
kg
| |
BENZENE
|
78
|
221.77
|
17298.38
|
114.24
|
8911.28
|
114.24
|
8911.28
| ||
PROPYLENE
|
42
|
112.00
|
4704.298
|
1.119
|
47.038
|
1.119
|
47.03
|
0
| |
PROPANE
|
44
|
5.89
|
259.38
|
5.89
|
259.38
|
5.89
|
259.38
|
0
| |
CUMENE
|
120
|
2.212
|
265.52
|
106.379
|
12765.5
|
106.37
|
12765.52
| ||
DIPB
|
162
|
0
|
0
|
3.360
|
544.35
|
3.360
|
544.35
| ||
TOTAL
|
22527.59
|
22527.5
|
306.42
|
223.98
|
22221.17
| ||||
Equipment
|
Benzene column top
|
Benzene column top
|
Cumene column top
|
Cumene column bottom
| |||||
Distilled benzene
|
Feed to Cumene column
|
Cumene product
|
DIPB by-product
| ||||||
Mw
|
kmole
|
kg
|
kmole
|
kg
|
kmole
|
kg
|
kmole
|
kg
| |
BENZENE
|
78
|
114.2473
|
8911.289
| ||||||
PROPYLENE
|
42
|
0
| |||||||
PROPANE
|
44
|
0
| |||||||
CUMENE
|
120
|
2.21274
|
265.5288
|
104.1667
|
12500.00
|
104.16667
|
12500
| ||
DIPB
|
162
|
0
|
3.360215
|
544.35483
|
0.10426
|
16.89012
|
3.255955
|
527.465
| |
TOTAL
|
9176.818
|
13044.35487
|
12516.89
|
527.465
| |||||
Equipment wise energy balance for 300 Ton/Day Cumene production pilot plant*
Benzene feed vaporizer:
(*refer process flowsheet)
The stream of mixed feed of benzene and cumene is feed to the vaporizer with 40
Component
|
Mol wt
|
kmole
|
Kg
|
mole fraction
|
mass fraction
|
BENZENE
|
78
|
221.7742
|
17298.39
|
0.990101
|
0.984851
|
CUMENE
|
120
|
2.2174
|
266.088
|
0.009899
|
0.015149
|
TOTAL
|
223.9916
|
17564.48
|
1
|
1
|
The bubble point and dew point of the mixture are found by using Antoine equation, the vapor pressure is calculated at various temperatures to find the saturated temperature
pi
|
xi
|
P
|
yi= pi xi /P
|
yi P
|
yi P/ pi
| |
BENZENE
|
2587.637
|
0.99
|
2533.125
|
1.011305
|
2507.794
|
0.969144
|
CUMENE
|
660.4975
|
0.01
|
2533.125
|
0.002607
|
25.33125
|
0.038352
|
∑
|
1.013912
|
1.007496
|
Where P is total pressure
Pi is vapour pressure at 243 oC. So, at 516 k the mixed feed will be vaporized.
Heat required for vaporize =313 int 516(C dT) + latent heat
Latent heat of benzene = 23,773.63 kJ/kmole
Latent heat of cumene = 30919.2 kJ/kmole
Average heat capacity of benzene = 161.46 kJ/kmole k
Average heat capacity of cumene = 246.92 kJ/kmole k
Enthalpy of benzene = Cp ∆T + λ = 161.46 X 203 + 23,773.63 = 56,550.01 kJ/Kmole
Enthalpy of cumene = 246.92 X 203+ 30919.2 = 81043.96 kJ/Kmole
Heat required for the mixed feed = 0.99 X 56550.01+0.1 X 81043.96
= 64088.89 kJ/Kmole
=64088.89 X 223.9= 14349502 kJ = 14349.502 MJ/h
Propylene feed vaporizer:
Propylene and propane fed from the tank with 25 oC at 25 atm.
The stream is vaporized and heat to the temperature 243oC and mixed with benzene feed.
Bubbling point and dew point of the mixture is about 62.5 oC
Latent heat of propylene = 17229.4 kJ / h
Latent heat of propane = 17611.41 kJ / h
The average heat capacity of liquid propylene =123.51
and propane=125.48
The average heat capacity of gaseous propylene = 82.86
and propane=97.48
Liquid state:
propylene
|
propane
| |
Cp
|
123.51
|
125.48
|
∆T
|
37.5
|
37.5
|
Q (kJ/h)
|
4631.625
|
4705.5
|
Gas state :
propylene
|
propane
| |
Cp
|
82.86
|
97.483
|
∆T
|
180.5
|
180.5
|
Q (kJ/h)
|
14956.23
|
17595.6815
|
Heat required for propylene:
17229.46+4631.625+14956.23 = 21861.08 kJ/h
Heat required for propane:
17611.39+4705.5+17595.075 = 39912.57 kJ/h
Heat required for the feed = 117.9 (21861.08 X 0.95 + 39912.57 X 0.05)
= 2683.83 MJ/h
Fired heater:
The heat required for raising the temperature reactant feed to 350 oC
inlet oC
|
= 243
|
outlet oC
|
= 350
| ||||||||
comp
|
kmole/h
|
heat capacity constants of gas mixture
| |||||||||
n
|
A
|
B
|
C
|
D
|
E
| ||||||
C3H6
|
112.0071
|
31.298
|
7.24E-02
|
1.95E-04
|
-2.16E-07
|
6.30E-11
| |||||
C3H8
|
5.8951
|
28.277
|
1.16E-01
|
1.96E-04
|
-2.33E-07
|
6.87E-11
| |||||
C6H6
|
221.7742
|
-31.368
|
4.75E-01
|
-3.11E-04
|
8.52E-08
|
-5.05E-12
| |||||
C9H12
|
2.21274
|
10.149
|
5.11E-01
|
-1.77E-05
|
-2.26E-07
|
8.80E-11
| |||||
nA
|
nB
|
nC
|
nD
|
nE
| |||||||
3.51E+03
|
8.11E+00
|
2.18E-02
|
-2.42E-05
|
7.05E-09
| |||||||
1.67E+02
|
6.84E-01
|
1.16E-03
|
-1.37E-06
|
4.05E-10
| |||||||
-6.96E+03
|
1.05E+02
|
-6.91E-02
|
1.89E-05
|
-1.12E-09
| |||||||
2.25E+01
|
1.13E+00
|
-3.92E-05
|
-5.00E-07
|
1.95E-10
| |||||||
Cp=
|
-3.26E+03
|
1.15E+02
|
-4.61E-02
|
-7.14E-06
|
6.53E-09
| ||||||
∆ T =
|
107
|
31725.5
|
9508697.667
|
2879866400
|
8.8098E+11
| ||||||
Cp∆ T=
|
-349019.239
|
3.65E+06
|
-4.39E+05
|
-2.06E+04
|
5.76E+03
| ||||||
∑ Cp∆ T=
|
2.85E+06
|
kJ/h
| |||||||||