ammonia synthesis by natural gas with the use of KBR process

1. AMMONIA SYNTHESIS BY KBR PROCESS
Submitted by-
Mohd Asif Siddique
Abhishek Gautam
Vineet Bhardwaj
Shashi Prakash Chaubey
Deo Narain Goswami
Sanchit Agarwal

2. Introduction
Ammonia, the most widely used intermediate for
making fertilizers, is usually manufactured by the
catalytic steam reforming of natural gas.
Natural gas has one of the highest proportions of
hydrogen among all fossil fuel feed stocks.
Hence, from an efficiency standpoint, natural gas is
an ideally suited feedstock for the manufacture of
ammonia.

3. History of Ammonia Manufacture
• Ammonia is synthesized from hydrogen
and nitrogen
• Nitrogen source is always air
• Hydrogen source has varied over the years

4. Hydrogen Sources for Making Ammonia
Process Reaction App. Relative Energy
Consumption
Water electrolysis 2H2O 2H2+ O2 300 %
Coal gasification C + 2H2O 2H2+ CO2 170 %
Heavy fuel oil CH + 2H20 2.5H2 + CO2 135 %
Naptha reforming CH2 + 2H2O 3H2 + CO2 104 %
Natural gas reforming CH4 + 2H2O 4H2 + CO2 100 %

5. CURRENT MANUFACTURING PROCESS
The proposed Ammonia Plant is based on the Kellogg Brown & Root (KBR)
Purifier™ ammonia process. The plant is a single continuous train using
natural gas as feedstock. The plant has a capacity of 1500 tonnes per day
(tpd), which is exported to atmospheric ammonia storage at -33C.

6. CHEMISTRY OF SYN GAS PRODUCTION
Process Chemical Reaction Favourable Condition
Primary Reforming heat + CH4 + H2O → 3H2 + CO High temp &
High stm/carbon
Secondary
Reforming
O2 + 2H2 → 2H2O + heat
heat + CH4 + H2O → 3H2 + CO
High temp &
High stm/carbon
High Temp Shift CO + H2O → CO2 + H2 + heat Low temperature
High steam/CO
Low Temp Shift CO + H2O → CO2 + H2 + heat Low temperature
High steam/CO
Process Equipment Features
Primary Reforming Catalyst-packed tubes in a furnace Nickel catalyst
Secondary Reforming Refractory-lined pressure vessel Nickel catalyst
High temp shift Pressure vessel Iron-chrome catalyst
Low temp shift Pressure vessel Copper-zinc catalyst

7. Primary Reforming
Secondary Reforming

8. Shift Conversion

9. Process Description Favorable Conditions
CO2 Removal Physical Dissolution or Chemical
Reaction
Low temp &
High pressure
Methanation CO + 3H2 → CH4 + H2O
CO2 + 4H2 → CH4 + 2H2O
280 - 350°C
Drying Physical Adsorption to remove
water & CO2
2 - 4 °C
Cryogenic
Purification
Separation of argon, residual CH4
and excess N2 from syngas
-180 °C
Chemistry of Syngas Purification

10. Syngas Purification

11. KBR Cryogenic Purifier

12. Process Description Favorable Conditions
Synthesis 3H2 + N2 → 2NH3 + heat Low T & high P
Heat Recovery Generate 100 bar+ steam High T
Product Recovery Condense via refrigeration Low T & High P
Process Equipment Features
Synthesis Catalyst filled pressure vessel P = 90 – 175 bar
T = 400 - 500 C
Heat Recovery Shell & tube heat exchanger Proprietary design
Product Recovery Compression refrigeration system Ammonia as the refrigerant
Engineering of Ammonia Synthesis
Chemistry of Ammonia Synloops

13. Refrigeration System
Ammonia Synthesis Loop

14. Advantages of KBR Process
 A clean, dry make-up gas reduces the load on the synloop compressor
and refrigeration systems, providing operational cost savings.
 Higher loop conversion is achieved with low inerts.
 No separate purge gas recovery unit is needed because purge gas
rejected from the synloop is passed through the Purifier unit.
 Achieves greater stability and flexibility of operation, since the reforming
section does not need to be tightly controlled to produce a precise H2/N2
ratio.
 Low reforming temperatures translate to lower stresses in and longer life of
reformer tubes.
 Numerous Purifier plants have run 3 - 4 years without a maintenance
shutdown.

15. Conclusion
The new KBR natural gas to ammonia process is based on the
KBR purifier reforming technology.
Integrated with proven KBR ammonia synthesis technology.
The process is well suited to a wide range of Natural gas
feedstocks.
 The process offers a robust and energy efficient design, with
several advantages when compared to traditional Natural gas to
ammonia processes.
It is an economically attractive option for manufacturing ammonia.

16. Thank You