kbr, mahesh gandhi
TRANSCRIPT
Technical innovations improving the sustainability and efficiency of the fertilizer industry
Mahesh Gandhi (MG)
Boost Ammonia Conversion Using KBR Ammonia Revamp Technologies Kellogg Brown & Root LLC
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2 ©2015 KBR, Inc. All Rights Reserved 2
• Safety Moment
• Overview - Why Retrofit?
• Current KBR Synthesis Loop Technology
• Impact of Increased Ammonia Concentration
• Converter Retrofit Options – Add-on Converter verses In-situ
– Cold Wall – the only choice
• Add-on Converter Options – With inter-changer & Without Inter-changer
• Conclusion
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Boost Ammonia Conversion Using KBR Ammonia Revamp Technologies
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SAFETY MOMENT
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YOU ARE RESPONSIBLE FOR YOUR SAFETY!
SAFETY STARTS WITH YOU – YOU CREATE A CULTURE OF
SAFETY
ZERO ACCIDENT MEANS EVERY ONE RETURNS HOME
IN THE CONDITION THEY CAME TO WORK!
Overview - Why Retrofit?
Simple Answer is Economics – lower per unit production cost
Most producers consider retrofit first before a new plant
Retrofitting also offers following additional advantages:
No increase in plot space or operating personnel
Not much additional operational training required
Not much change in the maintenance procedures
Minimum OSBL changes
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Vintage Ammonia Plants Need to Compete
• Increased Capacity
• Reduced Energy Consumption
• Reduced Natural Gas Usage
• Higher On-stream Factor
Low Cost Ammonia Production
•Well Integrated Proven Process
• Sustained Life-Cycle Benefit
•Guarantees to Support Viability
Successful Revamp Project &
Operations
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Ammonia Plant Revamp Technology
Ammonia Revamp
Process Flow-sheet
Existing Equipment
New Equipment
KBR Proprietary Equipment
Modified Equipment
• Implement as Integrated Whole Plant Flow-sheet
• Even One Bottleneck Missed in Scoping, Leads to Missed Capacity & Energy Targets
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Sections in an Ammonia Plant
Reforming Syngas
Purification Synthesis
Loop
Natural
Gas
Process Air CO2
NH3
Steam & Water System
Condensate
Steam
Make-up Water
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Ammonia Synthesis Loop - Typical
Syngas
HP Steam
CW
Synloop Purge
0 C
Syngas
Compressor
BFW
Ammonia Product
Converter System
Chilling System
Refrigeration
Compressor
Use dry make-up syngas or remove moisture by passing through ammonia chillers in loop
Hot side of the loop has converter, heat recovery to steam system & exchanger
Cold side has CW cooler, chilling, separator and purge
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CURRENT KBR SYNTHESIS LOOP
Syngas
CW
0 C
Refrigeration
Compressor
Horizontal Converter
Unitized
Chiller
BFW
NH3 Prod
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1 2 3-A 3-B
FEEDEFFLUENT
BYPASS OR
FROM 102-B
Horizontal converter with Three equilibrium stages with two
intercoolers.
Removable catalyst basket within the pressure shell.
An annular space exists between the cylindrical catalyst basket and
the high pressure shell to provide a path for feed gas cooling the
shell.
The process flow is downwards through each bed. Low pressure
drop. All of the feed gas passes through each of the catalyst beds.
Four beds, each filled with promoted iron catalyst of 1.5 - 3 mm at
top 90% and 3-6 mm granules bottom 10%.
1 2 3-A 3-B
FEEDEFFLUENT
BYPASS OR
FROM 102-B
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Ammonia Converter (105-D)
Ammonia Synthesis Loop- More Types
Syngas
BFW
HP Steam
Recycle
To Cooling & Chilling
First Converter
Second Converter
Syngas Compressor
Some synthesis loops have separate converters with external heat exchangers
Location of make-up gas addition to loop varies
Wet loops require a separate delivery of make-up syngas from compressor to chilling section
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Ammonia Converter Systems - Typical
Vintage converter systems are 3 adiabatic bed intercooled designs
Older vintage have 2 adiabatic bed intercooled designs
Vertical as well as horizontal converters in use
Converters with combined beds & intercoolers may typically have COLD WALL pressure vessel operating below ~250C
A separate converter to boost conversion after heat recovery requires HOT WALL vessel in grass-root or revamp project
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KBR Magnetite Ammonia Converters
Vertical converters
1960s to mid 80’s
(total ~150)
Initial vertical “Slim
Jim” with separate cold
product sweep gas
Two adiabatic bed
horizontal since 80’
Three adiabatic bed
horizontal since 90’
Vintage Braun
separate vertical
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Boosting conversion in ammonia synloop improves economics
Higher conversion provides more capacity & energy saving
More ammonia condensed in CW cooler, less duty on refrigeration
Less power for syngas & refrigeration machines saves fuel energy
Boosting Ammonia Conversion Helps…
Isothermal/MRR Adiabatic
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Disadvantages of Hot Wall Ammonia Converters
With given hot feed gas, vessel is exposed to high
temperatures in aggressive H2/N2 environment
High Cr-Mo hot wall vessel is thick, requires rigorous shop QC,
fewer vendors, expensive, low reliability
Hot wall converters seen to experience weld cracking over
period, cold wall have long life
Hot wall desired to have controlled pressurization/
depressurization & cooling/heating production loss
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Add Converter in Series to Boost Conversion
Adiabatic converter in series provides cost effective increase
in capacity & energy saving
Challenge is- the second converter must be hot wall design
due to hot feed gas
Add on converter typically has high risk & cost, due to
mandatory “hot wall”
KBR True Cold Wall Add On option provides risk mitigation &
low cost project
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Ammonia converter added in series to
boost conversion
Proven vintage MWK design, cold gas
sweep, like “Slim-Jim” of 1960’s
Cold wall 150+ still in use, 30-50 yrs
Patented annulus flow feature
KBR’s True Cold Wall Add-on Converter
Cooling
Gas
Feed
Product
Cooling
Gas
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Cold sweep gas stream passes through annular space, no mixing with reacting gas
Cold sweep stream taken from cold part of the synloop
Revamp for capacity gain, energy saving or reliability
Can also replace existing unreliable hot wall converters
Low cost, multiple vendors
KBR’s True Cold Wall Add-on Converter
Cooling
Gas
Feed
Product
Cooling
Gas
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Thin screen and profiled wire internals in existing converters nitride over years
Internals need replaced, typically done while replacing catalyst
KBR offers proven, 3 adiabatic bed, replacement basket for horizontal converter
KBR also offers 3 adiabatic bed, intercooled, in situ replacement basket for vertical MWK/KBR converters
We provide material and field services
KBR’s High Conversion Replacement
Baskets
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Boosting ammonia conversion in existing synthesis loop provides increased capacity and saves energy
Others require hot wall vessel, KBR’s True Cold Wall Add-on Converter provides reliable, low cost, effective revamp solution
Proven features of “Slim Jim” used
KBR also provides insitu replacement baskets for vertical and horizontal converters to boost conversion
Conclusion
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22 ©2015 KBR, Inc. All Rights Reserved