Energy Balance

March 1, 2019 | Author: usman0553 | Category: Nature, Mechanical Engineering, Gases, Chemical Process Engineering, Materials
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Short Description

an energy balance to maleic anhydride production from benzene plant...

Description

ENERG

Compressor K-100:

Inlet Conditions: Outlet conditions: mass flow rate of air

Temperature Pressure ### 1.07

303 K 202 Kpa

kg/hr kgmol/sec

Inlet volumetric flow rate:

26.74 poly tropic efficiency 76% Outlet temperature for poly-tropic flow:

then

m T2

Work per mole for poly-tropic flow

0.38 393.2 K

m3/sec

120.05 C

n Work

1.6 68.9

KJ/kgmol

Power Requirement actual work power requirment

90.66 97.45

KJ/kgmol KW

Air Pre-heater E-101:

Inlet conditions Outlet conditions reference temperature moisture in air

heat taken by air

temperature temperature 120 C 107.5 kgmol

120.05 C 380 C

### KJ/hr

Benzene Pre-heater E-100:

Inlet conditions temperature Outlet conditions temperature boiling point of benzene 104.7 C reference temperature 30 C heat taken by benzene feed from benzene preheater

30 C 110 C

Pressure Pressure

heat taken by benzene

###

KJ/hr

Feed Mixer MIX-100:

reference temperature

110 C

Assuming Tmix average temperature

350 C 230 C

component

m (kgmole/hr)

Air Benzene

Cp (KJ/kgmole oC)

### 59.02

### (Tmix-110)

=

30.57 59.02 ### Tmix 363.36 C

Reactor PFR-100:

Chemical Reactions: C6H6 + 4.5 O2 C6H6 + 7.5O2 C6H6 + 4.5 O2

C4H2O3 + 2CO2 +2H2O (Maleic Anhydride) 6CO2 +3H2O 6C0 + 3H2O

C6H6 + 1.5 O2

C6H4O2 + H2O (quinon)

At steady state Heat input to reactor = Heat output from reactor

component

m

Air Moisture Benzene

Cpℓ 3816 107.5 59

entahlpy of reactants

ΔTℓ

72.94 133

75 53

### KJ/hr

Enthalpy of products leaving at 400C: component Nitrogen Oxygen Water CO2 MAN CO Benzene Quinone

m

Cpℓ 3014 512 225 122 43 26 5 0.94

ΔTℓ

72.94

75

158

177

133 182

53 155

Enthalpy of products leaving at 400C

###

Heat produced by reactions assuming reaction takes place at 25C By reaction (R1) By reaction (R2) By reaction (R3) By reaction (R4) Total Heat of reaction at 25C ΔHR Heat taken by cooling salt

Waste Heat Boiler E-102:

### ### ### ### ### ###

Product steam (8) from the reactor is cooled from 400C to 76.5C at 152Kpa. For ener balance around Waste Heat Boiler assume 76.5C as reference temperature. average temperature

238.25 C

enthalpy of stream (8) component Nitrogen Oxygen Water CO2 MAN CO Benzene Quinone

m

Cpℓ 3014 512 225 122 43 26 5 0.94

ΔTℓ

73.56

24

163

126

189.2

104

Heat removed in waste heat boiler

Pre-scrubber cooler E-103:

Stream(11) is cooled from 76.5C to 50C before it enters Gas Scrubber. For energy ba assuming 50C as reference temperature.

heat removed in pre-scrubber = {ehtahlpy of stream (12)}-{enthalpy of stream (11)

component

m

Nitrogen Oxygen Water CO2 MAN CO Benzene Quinone

Cpℓ 3014 512 225 122 25.35 26 4.71 0.71

ΔTℓ

72.94

26.5

148

26.5

137 171.2

26.5 26.5

heat removed in Pre-Scrubber cooler

Mixer MIX-101:

Pure water stream (16) is added to scrubbed liquid (13) to keep the concentration of solution up to 40%. Assuming water enters at 30C and 101Kpa while scrubbed liquid entering at 45C. stream (15) and (17) are leaving at same temperature. So T15 = T17 = T Energy balance around mixer MIX-101 is

assuming 30oC as reference temperature Enthalpy of stream (13) component Water MAC Quinone

m 4426.43 495.81 0.71

Cpℓ 72.8 206.5 164.3

ΔTℓ 15 15 15

Total Enthalpy

### KJ/hr

Enthalpy of stream (15) component

m

Water MAC

Cpℓ 4551.1 470.9

Total Enthalpy

72.8 206.5 ### (T-30)

ΔTℓ (T-30) (T-30) KJ/hr

Enthalpy of stream (17) component Water MAC Quinone

m

Cpℓ 236.3 24.89 0.71

Total Enthalpy

72.8 206.5 164.3 ### (T-30)

ΔTℓ (T-30) (T-30) (T-30) KJ/hr

temperature of stream(15) and (17)T

### 44.1

Scrubber T-100:

MAN is absorbed in 40% solution of MAC entering at 44.2C while the gases leaves fro of scubber in vent stream (14). For energy balance assuming 44.2C as reference temperature.

Reaction involved in scrubber Reaction taking place: C4H2O2 + H20

C4H4O4 (maleic acid) ∆H

### KJ/kgmol

m

Cpℓ

Enthalpy of stream (12) component Nitrogen Oxygen Water CO2 MAN CO Benzene Quinone

3014.4 512 234 122 25.35 26.22 4.71 0.71

ΔTℓ

29.33 29.51 72.78 39.25 144.4 29.91 133.3 167 Total Enthalpy

6.8 6.8 6.8 6.8 6.8 6.8 6.8 6.8 ###

Enthalpy of stream (13) component Water MAC Quinone

m

Cpℓ

4426.43 495.81 0.71

ΔTℓ

72.8 206.5 164.3 Total Enthalpy

0.8 0.8 0.8 ###

Enthalpy of stream (14) component Nitrogen Oxygen Water CO2 MAN

m

Cpg 3014 512 333.6 122 0.43

29.26 29.48 72.79 39.16 144.4

ΔTg (T-44.2) (T-44.2) (T-44.2) (T-44.2) (T-44.2)

CO Benzene

26 4.71

29.22 131.2

(T-44.2) (T-44.2)

Total Enthalpy energy balance provides

T14

### 48.03 C

Dehydrator feed pre-heater E-104:

Feed is heated from 44.2C to 95C in vapor phase befor it enters the dehydrator component Water MAC Quinone

m

Cpℓ 236.3 24.89 0.71

ΔTℓ

73.1 215.8 173.6

heat duty of Dehydrator feed preheater

Dehydrator T-101:

Operating conditions:

51 51 51

Top plate temperature = 55C Re-boiler temperature = 120 C Operating pressure = 15.2 kpa Assuming 100C as reference temperature Reactions involved

(maleic acid)

(fumaric acid)

Overhead condenser:

Overhead product is condensed from 55C to 45C at 15.2Kpa. Boiling point of water at 15.2Kpa = 53. Boiling point of O-xylene at 15.2Kpa = Taking 25oC as reference temperature Enthalpy of stream (19) component

m

Water O-xylene

Cpℓ 248 72

72.77 194.3 Total Enthalpy

Enthalpy of stream (20) component Water O-xylene

m

Cpℓ 248 72

72.77 192.3 Total Enthalpy

heat duty of overhead condenser

heat duty of overhead condenser

###

Enthalpy of stream (18) entering at 95C and 101Kpa component

m

Water MAC Quinone

Cpℓ 236.3 24.89 0.71

72.9 212.4 170.4 Total Enthalpy

Enthalpy of stream (26) leaving at 120oC and 15.2KPa component Water MAN O-xylene Fumaric acid Quinone

m

Cpℓ 13.07 24.77 3.79 0.12 0.71

72.77 149.7 200.4 251 173.8 Total Enthalpy

Enthalpy of reflux stream (21)

###

Heat required by reaction (R1)

###

Heat required by reaction (R2)

###

Total heat required for reactions

###

heat duty of Re-boiler

heat duty of Re-boiler

Mixer MIX-102

Stream (27) entering at 120oC and 101Kpa is mixed with cr

Assuming 25oC as reference temperature so Enthalpy of st component

m

Water MAN O-Xylene Fumaric Acid Quinone

13.07 24.77 3.79 0.12 0.71

Enthalpy of stream (28) component

m

Water MAN O-Xylene Fumaric Acid Quinone

14.75 42.51 3.79 0.12 0.94 Total Enthalpy

Enthalpy of stream (10) component water

m 17.74

MAN quinon

1.68 0.23

enthalpy balance around mixer is ### = ###

Distillation Coulmn T-102

Operating conditions: Top plate temperature = 160oC Re-boiler temperature = 200oC

Ope

Assuming 25C as reference temperature Enthalpy of feed stream (29) entering at 108C component Water MAN

m 14.75 42.51

O-Xylene Fumaric Acid Quinone

3.79 0.12 0.94

Enthalpy of stream (30) component

m

Water MAN O-Xylene Quinone

54.15 1.03 13.27 3.06

Enthalpy of stream (31) component

m

Water MAN O-Xylene Quinone

36.9 0.73 9.5 2.2

Enthalpy of stream (32) component

m

Water MAN O-Xylene Quinone

14.75 0.29 3.79 0.87

Enthalpy of stream (36) component MAN Fumaric Acid Quinone

m 42.21 0.12 0.17

Heat duty of condenser

Heat duty of condenser Heat duty of re-boiler

ENERGY BALANCE

Pressure

101 Kpa

4

2 1.3

0.38 R Zi

Pressure Pressure

202 Kpa 202 Kpa

202 Kpa 202 Kpa

1.3 0.3 231.47 0.08 m3atm/kgmolK 8.31 KJ/kgmolK 1

m Cp ### ###

(R1)

∆H

### KJ/kgmol

(R2)

∆H

### KJ/kgmol

(R3)

∆H

### KJ/kgmol

(R4)

∆H

### KJ/kgmol

tput from reactor

CpℓΔTℓ

5470.5 7049

CpℓΔTℓ

5470.5 27966 7049 28210 KJ/hr

KJ/hr KJ/hr KJ/hr KJ/hr KJ/hr KJ/hr

Cpg

ΔTg

32.21 35.65 136.4

Cpg 30.16 30.94 35.83 43.87 162.5 29.81 140.4 172.6

Cpg∆Tg 338 263 285

ΔTg

### ### 38874

Cpg∆Tg 375 375 300 375 198 375 322 220

λ

11310 ### 10749 ### 32175 ### ### 37972

### ###

λ

### ### ### ###

.5C at 152Kpa. For energy e temperature.

CpℓΔTℓ

### 20538

### ### KJ/hr

Scrubber. For energy balance

enthalpy of stream (11)}

Cpg 30.27 31.18 35.77 44.47 162.2 29.93 140.2 172.3

ΔTg

Cpg∆Tg 324 324 300 324 198 324 322 220

### ### 10731 ### ### ### ### 37906

λ

### ### ### ###

CpℓΔTℓ

Cpg

ΔTg

Cpg∆Tg

29.4 29.6

26.5 26.5

779.1 784.4

39.72

26.5

###

29.22

26.5

774.33

### 3922 3630.5 4536.8 ### KJ/hr

ep the concentration of MAC pa while scrubbed liquid is

5 = T17 = T

CpℓΔTℓ 1092 3097.5 2464.5

∆H ### ### 1749.8

λ

∆H ### (T-30) ### (T-30)

∆H ### (T-30) ### (T-30) 116.65 (T-30)

C C

hile the gases leaves from the top

C4H4O4 (maleic acid)

CpℓΔTℓ 199.44 200.67 494.9 266.9 981.92 203.39 906.44 1135.6

∆H ### ### ### ### ### ### ### 806.28

KJ/hr

CpℓΔTℓ 58.24 165.2 131.44 KJ/hr

∆H ### (T-44.2) ### (T-44.2) ### (T-44.2) ### (T-44.2) 62.09 (T-44.2)

∆H ### ### 93.32

759.72 (T-44.2) 617.95 (T-44.2) (T-44.2) KJ/hr

ers the dehydrator CpℓΔTℓ 3728.1 ### 8853.6

### KJ/hr

∆H ### ### ###

e = 120 C = 15.2 kpa

∆H

### KJ/kgmol

∆H

### KJ/kgmol

45C at 15.2Kpa. water at 15.2Kpa = 53.6C O-xylene at 15.2Kpa = 85.05C

ΔTℓ

CpℓΔTℓ

28.6 30

Cpg

2081.22 5829

33.8

### KJ/hr

ΔTℓ

CpℓΔTℓ 20 20

### KJ/hr

1455.4 3846

∆H ### 276912

ΔTg

Cpg∆Tg 1.4

47.32

KJ/hr

ΔTℓ

CpℓΔTℓ 70 70 70

5103 14868 11928

∆H ### ### ###

### KJ/hr

ΔTℓ

y of Re-boiler

28.6 95 60 95 95

CpℓΔTℓ 2081.22 14221.5 12024 23845 16511 ### KJ/hr

### KJ/hr

Cpg

ΔTg

Cpg∆Tg

34.03

66.4

###

163.1

35

5708.5

101Kpa is mixed with crude MAN stream (10).

rature so Enthalpy of stream (27) Cpℓ

ΔTℓ

CpℓΔTℓ

72.77 149.7 207 251 173.8

75 95 95 95 95

### ### 19665 23845 16511 Total Enthalpy

Cpℓ 73.12 149.7 207 251 173.8 Total Enthalpy

Cpℓ 145.3

Cpg

ΔTℓ

CpℓΔTℓ 75

ΔTg

34.42

20

### KJ/hr

Cpg

5484

34.4

ΔTg (T-100)

(T-25) (T-25) (T-25) (T-25) 670889

ΔTℓ

+

507.4 (T-100) +

CpℓΔTℓ 51.5

###

### (T-25)

∆H ###

72.8 168.5

51.5 51.5

3749.2 ###

Total Enthalpy

670889

T

### KJ/hr

+

=

### ###

507.4 (T-100) +

### + =

### (T-25)

### T 95.42 C

Top plate temperature = 160C Re-boiler temperature = 200 C Reflux temperature

= 112C

Operating pressure = 101 kpa ce temperature

29) entering at 108C Cpℓ 73.12 148.4

ΔTℓ

CpℓΔTℓ 75 83

5484 ###

Cpg 34.38

ΔTg 8

204.9 250.2 172

83 83 83

Total enthalpy

Cpℓ

### KJ/hr

ΔTℓ

73.12 153.6 212.3 179.1

CpℓΔTℓ 75 135 119 135

Total enthalpy

Cpℓ

ΔTℓ

CpℓΔTℓ 75 87 87 87

Total enthalpy

ΔTℓ

5484 ### ###

CpℓΔTℓ 75 87 87 87

Total enthalpy

157.8 256.6 181.9

ΔTg

34.57

60

181.8

16

Cpg

ΔTg

34.38

12

### KJ/hr

73.12 148.4 204.9 172

Cpℓ

5484 20736 ###

Cpg

### KJ/hr

73.12 148.4 204.9 172

Cpℓ

### ### 14276

5484 ### ### 14964

Cpg

ΔTg

34.38

12

### KJ/hr

ΔTℓ

CpℓΔTℓ 175 175 155

27615 44905 ###

Cpg

152.2

ΔTg

20

Total enthalpy

### KJ/hr

condenser

uty of condenser

### KJ/hr

re-boiler

Heat duty of re-boiler

### KJ/hr

∆H ### ### ###

∆H ### ### ### ### ### ### 406289 ###

∆H ### ### ### ### ### ### 375722 ###

∆H ### ### ### ### ### ### ### ###

λ

∆H ###

### 419688

λ

∆H ### ###

### ### ### 2861.4 ###

Cpg∆Tg

λ

688.4

Cpg∆Tg 34.4 (T-100)

∆H ###

λ

### ### ### 2861.4 ###

∆H ###

670889 + ### (T-25) 784.53 (T-25) 30.12 (T-25) 163.37 (T-25)

507.4 (T-100)

Cpg∆Tg 275.04

λ

∆H 40000

### ###

### ### ###

Cpg∆Tg

λ

∆H

2074.2

40000

2908.8

37000

Cpg∆Tg

λ

412.56

Cpg∆Tg

3044

∆H 40000

λ

412.56

Cpg∆Tg

### ### ###

### ### ###

∆H 40000

λ

### ### ### ###

∆H

46000

### 5388.6 ###

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