The document discusses various aspects of ammonia production processes including:
1) Simplified block diagrams of typical ammonia, methanol, and hydrogen production plants showing the main process units.
2) Modern conventional ammonia plant flowsheets have the same main process steps but differ in equipment designs between vendors.
3) Other flowsheet options for ammonia production including the Braun Purifier process, ICI AMV, ICI LCA, dual pressure Uhde process, and Linde LAC process.
4) Additional process modifications and options such as gas turbine drives, pre-reformers, heat recovery techniques, synthesis gas driers, and booster converters.
5. Simplified Block Diagram of a
Hydrogen Flowsheet
Desulfurization
Primary Reforming
High Temperature
CO Shift
VHT-S101
VSG-
Cl101
VSG-
EZ200
VSG-
Z101
VSG-
F101
PSA
etc
SteamNatural Gas Feed
Hydrogen
6. Simplified Flowsheet for a Typical
Ammonia Plant
Natural
Gas
Steam
superheater
Air
Steam
30
bar
Steam
Steam
raising
350 C
200 C
Heat
Recovery
Steam
raising
Cooling
Cooling
Reboiler
CO
Cooling
Preheater
Heat
Recovery
Steam
Boiler
Process
Condensate
Quench
Quench
Liquid Ammonia
H
Hydrodesulphuriser Primary
Reformer
Secondary
Reformer
High
Temperature
Shift
Low
Temperature
Shift
Ammonia SynthesisMethanator
Carbon Dioxide
Purge Gas
Cooling
400 Co
390 Co
2
790 C
o
550 Co
1000 Co
o
420 Co
150 C
o
400 Co
470 C
o
o
220 C
o
290 Co
330 Co
2
CO Removal2
220 bar
Refrigeration
Condensate
Cooling
Ammonia
Catchpot
7. Modern Conventional Flowsheets
Main process steps are the same for all plants
Main differences in equipment design
Uhde
Top fired reformer
Proprietary exit header design
Secondary reformer has a riser
HP loop with radial flow converter
8. Modern Conventional Flowsheets
HKBR
Primary reformer with manifold/riser
Haldor Topsøe
Side fired reformer
Radial flow converter
S-200
S-250
9. Other Flowsheet Options
Braun Purifier
ICI AMV
ICI LCA
Dual Pressure Uhde Process
HKBR KAAP (with/without purifier)
Linde LAC
H2 Recovery is used on most
modern plants
10. Braun Purifier Process
Primary reformer exit temperature is 700°C
Excess air is added to the secondary reformer
Methane slip typically around 2-2.5 mol %
Excess nitrogen (and methane) cryogenically
removed downstream of methanator
Also removes water - ammonia synthesis catalyst
poison
Improved synthesis lives
Can reduce SC ratio to 2.7-3.0
Small primary
12. ICI AMV Process
As with Braun - utilizes excess air to secondary
Excess nitrogen is passed to the loop
Loop runs at low pressure (80-110 bara)
Use ICI LP Catalyst (74- Series)
Uses a saturator to saturate feed gas
This raises around 50% of the required steam
Can use SC ratio of 2.8
H2 Recovery in loop at loop pressure
13. ICI LCA Process
Aim at small plant capacities (500 mtpd)
Uses the GHR-Secondary concept
Excess air is utilized to close heat balance
Utilizes an ITS rather than HTS and LTS
A saturator for steam raising
A PSA system to remove the CO2 and excess N2
A low pressure loop (80 bara)
A tube cooled converter or Casale converter
No longer actively marketing
14. Dual Pressure Uhde Process
PGR Unit
Make up gas
from frontend
H2O
Ammonia from once through conversion
HP-
steam
C.W.NH3
NH3
C.W.
C.W.
C.W.
HP-
steam
NH3 NH3
Off-Gas
Ammonia
from
HP loop
HP
casing
LP
casing
First
ammonia
converter
Second
ammonia
converter
Once
through
ammonia
converter
HP-
steam
Note: Molecular
Sieves not shown
15. Dual Pressure Uhde Process
Benefits of such a scheme realised at 3,000
mtpd +
Although this is large capacity - all equipment is
proven
Note the low pressure converter between stages
of synthesis gas machine
Makes machine smaller
Makes loop pipework 24”
Uses Comp. J catalyst
16. HKBR Purifier and KAAP
Primary
Reformer
Secondary
Reformer
Shift &
CO2
Removal
Purifier
CompressionKAAP
Meth’n
Dryers
Recycle Purge
To Fuel
Feed
17. Linde LAC
Key features are
No secondary reformer
Nitrogen is generated cryogenically and
added after a PSA unit
No HTS/LTS - only Isothermal (ITS) shift
No methanation
19. Other Flowsheet Options
Use Gas Turbine to drive process air
compressor
Can use effluent as combustion air
Has 16-17% O2 and is at 500°C
Braun plants
Install pre reformer
HT Retrofit
Many other reasons
Remove heat from duct
Uprate plant
20. Other Flowsheet Options
Synthesis Gas driers
Reduces H2O in syn gas
H2O is a poison
Activity increases
Ammonia Wash
As per Syn Gas driers
Booster converters
Drop load on loop and allow overall output
increase
Quenches in Shifts
21. Ammonia Flowsheet Data Analysis
Tool - VULCAN CERES
Looks at all catalytic unit operations
Highlights potential issues/in-correct data
items
Functionality to address flowsheet options
Kellogg risers
Differential flowsheet conditions (Braun)
Use as a basis for
Predictions of future performance
Predictions of new catalyst options
Uprates