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1. National Fertilizers Ltd.
Bathinda
AJAY NAGAR
10112001

2. Sections

Ammonia Plant

Urea Plant

Steam Generation Plant

Bagging Plant

3. Ammonia Plant

Desulphurization Section

Reforming Section

Shift Section

Carbon Dioxide Removal Section

Methanation Section

Ammonia Synthesis Section

4. Desulphurization Section
Natural Gas With
Recycle Hydrogen
Natural Gas Feed
HYDROGENATOR:
•
Reactions involved in Hydrogenator are:
Recycle Hydrogen → RH + H S
RSH + H2
2
Feed Gas Preheater
R1SSR2 + 3H2 → R1H + R2H + 2H2S
R1SR2 + 2H2 → R1H + R2H + H2S
COS + H2 → CO + H2S
•
400oC
38 Kg/cm2
395oC
Sulphur
Absorber
No. 1
Sulphur
Absorber
No. 2
If some content of CO2 is also exist in Natural Gas feed then:
CO₂ + H₂ ↔ CO + H₂O
CO₂ + H₂S ↔ COS + H₂O
•
Hydrogenator
CoMo or NiMo based catalyst is used in Hydrogenator.
395oC
351o

5. Desulphurization Section
H₂S ABSORBER:
•
The Hydrogenated Natural Gas is fed to the Sulphur Absorbers.
•
Zinc oxide catalyst is in the form of 4 mm cylindrical extrudates.
•
Operating temperature is approx. 395˚C.
ZnO + H₂S ↔ ZnS + H₂O
ZnO + COS ↔ ZnS + CO₂
•
Sulphur content in the natural gas is less than 0.1 ppm by weight.

6. Reforming Section

Desulphurized gas is converted into synthesis gas by catalytic reforming of the
hydrocarbon mixture with steam and the addition of air.

Reactions involve in Reformer Section:
CnH2n+2 + 2H₂O ↔ Cn-1H2n + CO₂ + 3H₂ - heat
CH₄ + 2H₂O ↔ CO₂ + 4H₂ - heat
CO₂ + H₂

↔ CO + H₂O – heat
Reactions take place in two steps
1.
Primary reforming
2.
Secondary reforming

7. Primary Reformer
Process Air
Preheater
Product Stream of Primary Reformer
Desulphurized Gas
 As we have seen that we areComposition : (Mole
getting around
Steam Carbon Mole Ratio=3/1
%)
12.86 mole % of methane and we don’t want
(At Inlet of Catalyst
Process Steam
Tubes)
it to be exist in stream just because it will be
Ar – 0.02
CH4 – 79.68
acting as inert in whole further processes.
CO – 2 ppm
CO2 – 0.24
So we have to remove it. Composition of catalyst (% w/w)
H2 – 4.09
N2 – 2.54
1. Nickel Monoxide, NiO (17)
 `For removing this access of methane we
C2H6 – 6.48
2. Calcium Oxide, CaO (7)
Primary
Potassium
use Secondary Reformer. 3.C3H8 – 2.63 oxide, K2O (4)
Reformer
C4H10 – 1.88
4. Aluminum Oxide, Al2O3 (Balance)
C6H12 - 0.24
520oC
34 - 31 kg/cm2 g
Composition:
(Mole %)
(At Outlet of
Catalyst Tubes)
Ar – 47 ppm
Secondary CH4 – 12.86
Reformer CO – 9.5
CO2 – 10.70
H2 – 66.20
N2 – 0.74
Higher HC –
Neglegible
785-795oC Process Gas

8. Secondary Reformer
•
•
•
•
The process gas is mixed with air with keeping the
ratio of H2/N2 Ratio: 3.0.
Partial combustion takes place in the top of reactor.
Methane concentration is 0.60 mole%.
Outlet gas contains about 13.05mole% CO and
7.24mole% CO₂ that are removed further because
catalyst may get poisioned.
Gas inlet
composition (mole%) 791oC
Ar – 47 ppm
CH4 – 12.86
CO – 9.5
CO2 – 10.70
30 kg/cm2 g
H2 – 66.20
N2 – 0.74
Catalyst
composition(%mole):
NiO = 8 – 10%
Al2O3 = 87 – 90 %
Cao = < 0.05 %
550oC
1100-1200oC
Gas outlet
composition (mole%)
Ar – 0.27
CH4 – 0.60
CO – 13.37
CO2 – 7.65
H2 – 55.61
N2 – 22.47
958oC

9. CO Shift Section
•
Exothermic reaction which occurs in this section is:
CO + H2O ↔ H2 + CO2 + heat
•
Shift reaction takes place in the two CO converters:
1.
HT CO-Converter.
2.
LT CO- converter with process gas cooling after each converter.

10. HT/LT CO Convertors
Composition (mole%)
Process
of inlet gas from of HT Section
stream Reformer
CO Converter is:
Ar – 0.27, CH4 – 0.60,
CO Catalyst’s composition
– 13.37, CO2 –
(mole%) which is
7.65, H2 – 55.61, N2 –
HT CO
available in pellet form.
22.47
Fe2O3 85- Convertor
95 %
Cr2O3 7-9 %
CuO 1-2%
Al2O3 1.0%
432oC
360oC
29.6kg/cm2
205oC
28.6kg/cm2
(mole%)
Composition
of outlet stream of HT
CO Converter is:
Ar – 0.24, CH4 – 0.55
CO – 3.22, CO2 –
Methanator trim
15.94
heater
H2 – 59.59, N2 – 20.48
340oC
Waste heat
boiler
205oC
BFW Preheater 1
Catalyst consist the
oxides of Cu, Cr and
Composition (mole%)
LT CO
Al, Which is most
Convertor of outlet stream of LT
active in between 170250oC. CO Converter is:
Ar – 0.24, CH4 – 0.53
CO – 0.30, CO2 –
18.32
H2 – 60.73, N2 – 19.88
227oC
160oC
BFW Preheater 2

11. CO2 Removal Section
•
•
•
•
Outlet gas from CO converter contain 18.32 mole% CO2
Based on two stage activated MDEA process
The solvent used for CO2 absorption is aMDEA(40%)
Consists of a two stage CO2 absorber, a CO2 stripper and
two flesh vessels.
• These are the reactions occurs in CO2 removal section.
R3N + CO2 + H2O ↔ R3NH+ + HCO32R2NH + CO2 ↔ R2NH2+ + R2N-COO-

12. CO2 to Urea
72˚C
0.59 Kg/cm2
Chiller
Condensate
50˚C
5.1 Kg/cm2
Cooler
Flash gas/ Inerts
LP
Flash
160˚C
27.8 Kg/cm2
Output after CO2
Absorption
60˚C
26.8 Kg/cm2
95˚C
Stripper
Pump
Stripper
Reboiler
HP
CO2 Absorber
HE
Lean Solution
L S Pump
65˚C
27.8 Kg/cm2
131˚C
Semilean Soln
BFW
Preheater
65˚C
Process gas
saparator
65˚C

13. Methanation Section

Methanation, a process in which the residual Carbon Oxides (CO, CO2) are converted into
METHANE because it acts as inert in Ammonia Synthesis Section.

Reactions involve in Methanator are:
CO + 3H2 ↔ CH4 + H2O + heat
CO2 + 4H2 ↔ CH4 + 2H2O + heat

As we can see these reactions are exothermic so Low temperature, high pressure and a
low water vapour content favours the methanation equilibrium.

After converting all Carbon Oxides into METHANE, product stream is pressurised from
25Kg/cm2 to 187Kg/cm2 by using compressors and gas boosters and for maintaining
temperature, chillers are being used.

14. 300˚C
Process gas for
LT CO Converter
Nickel based catalyst
Methanator
is used here in methanator
which consist around 27%
wt Nickel. (280-420˚C)
Process gas from
HT CO Converter
Trim
heater
322˚C
Composition(%mole)
at inlet is:
Ar- 0.29, CH4- 1.08,
H2- 73.95, N2- 24.88
Synthesis gas to loop
285˚C
90˚C
25 Kg/cm2
Gas/Gas
HE
60˚C
26.8 Kg/cm2
Composition(%mole)
at inlet is:
Synthesis Gas From
Ar- 0.29, CH4- 0.65,
CO2 Removal Section
CO2-0.05,CO-0.36,
H2- 74.29,N2- 24.36

15. Ammonia Synthesis Section
3H2 + N2 = 2NH3 + heat (ΔH = −92.4 kJ/mol)
•
•
•
•
Feed gas inlet
130˚C
187 Kg/cm2
Fe Oxied (Fe3O4) % wt
93 ± 2
High pressure and low temperature favourable equilibrium conditions of ammonia
CaO, Al2O4, K2O, SiO2, % wt 7 ± 2
reaction.
With the irregular shape beads
About 20% of N2 and H2 is converted into ammonia at given operating conditions.
with the size of 1.5-3mm
Unconverted remainder is recycled back.
Bulk density 2.8kg/l
There are three beds we use in Ammonia Convertor:
First bed : 370-510 ˚C
Second bed: 425-480 ˚C
Third bed: 420-460 ˚C
Feed gas inlet
Outlet
354˚C
Feed gas inlet 183.6 Kg/cm2

16. Composition(mole%) of
10˚C
Purge Gas of Ammonia
2
178.9Kg/cm Converter
Purge Gas
Ar- 2.49, CH4- 8.38
H2- 82.48, N2- 20.82
NH3- 5.82
Composition(mole%) at
Startup Ammonia
Inlet of
Heater
Converter
Ar- 1.82, CH4- 6.18,
130˚C
H2- 65.95, N2- 21.99,
2
NH3- 4.06 187Kg/cm
Ammonia
Converter
Synthesis
Hot
Composition(mole%) at
Heat
Steam
Outlet of Ammonia Exchanger
HE
Boiler
Converter
354˚CAr- 2.11, CH4- 7.14
270˚C 180˚C
Cooler
H2- 52.84, N2- 17.61
NH3- 20.30
10˚C
Chiller
Composition(mole%) of Let
Ammonia Down Gas of Ammonia
Separator Converter
Ar- 3.16, CH4- 16.12
11˚C
H2- 38.06, N2- 15.76
27Kg/cm2 Let Down
NH3- 26.88
Gas
10˚C
Makeup Synthesis
Gas
Product let
Down tank
Compressors
Composition(mole%) of Product
Ammonia
Stream of Ammonia Converter
(Product)
Ar- 0.01, CH4- 0.16
12˚C
H2- 0.06, N2- 0.04
25Kg/cm2
NH3- 99.73

17. Ammonia Recovery
61˚C
20Kg/cm2
Composition(mole%) of
Fuel Gas:
Ar- 2.71, CH4- 9.46
Fuel Gas H2- 65.73, N2- 22.08
NH3- 0.01
Ammonia
OH Drum
Purge Gas
Absorber
Composition(mole%) of
Purge Gas:
Ar- 2.49, CH4- 8.38
H2- 82.48, N2- 20.82
10˚C
NH3- 5.82
178.9Kg/cm2
Purge Gas
Composition(mole%) of
Let Down Gas
Let Down Gas: 11˚C
Ar- 3.16, CH4- 16.12
27Kg/cm2
H2- 38.06, N2- 15.76
NH3- 26.88
Steam
248˚C
Distillation
Column
Ammonia
Reflux
Lean Soln
Cooler
Richlean
Soln
Exchanger
Circulation Pump
Reboiler
45˚C
Composition(mole%) of
2
25Kg/cm
Product Gas:
Ar- 64ppm, CH4- 0.03
Ammonia
H2- 0.06, N2- 0.02
NH3- 99.88

18. Conclusion

National Fertilizer Ltd. Bhatinda is producing 99.80% pure Ammonia
by Using Natural Gas with the help of helder tropsch method for
further production of Urea.

19. “
Thank You !!!
”