This presentation highlights some of the retrofits that can be applied to Improve efficiency Increase production

1. Revamps for Ageing
Ammonia Plants
By;
Gerard B. Hawkins
Managing Director

2. Introduction
 This presentation highlights some of
the retrofits that can be applied to
• Improve efficiency
• Increase production
Safety
Efficiency
Reliability
Throughput
Environment

3. Introduction
 Why consider a retrofit?
 Limitations
 Options for retrofits
 Problems and Pitfalls
 GBHE Catalysts and Retrofits
 Conclusions

4. Why Consider a Retrofit?
 Plant is
• Inefficient
• Has poor economics
• Production can be increased by
elimination of bottlenecks
 Retrofits generally are more cost
effective than new plant builds

5. Plant Limitations
 Six main areas that can limit plant
performance
Primary

6. Plant Limitations
 Six main areas that can limit plant
performance
Primary
Convection Section

7. Air Compressor
and Secondary
Plant Limitations
 Six main areas that can limit plant
performance
Primary
Convection Section

8. Plant Limitations
 Six main areas that can limit plant
performance
Primary
Convection Section
Air Compressor
and Secondary
Cooling, Shifts
and CO2 Removal

9. Plant Limitations
 Six main areas that can limit plant
performance
Primary
Convection Section
Air Compressor
and Secondary
Cooling, Shifts
and CO2 Removal
Compression

10. Plant Limitations
• Six main areas that can limit plant performance
Primary
Convection Section
Air Compressor
and Secondary
Cooling, Shifts
and CO2 Removal
Compression
Ammonia
Synthesis

11. Pre-Reformers
 Installation of pre-reformer helps to
de bottleneck
• The primary reformer - reduced box
duty
• The convection section - heat removal
• Eliminates heavies/ poisons
 Can increase plant rate by up to
11%
 Will affect steam balance

12. Change Catalyst Shape and
Size
 By optimizing catalyst size can
• Reduce pressure drop by up to 33%
• Reduce carbon formation potential
 By changing to VULCAN VSG-Z101 can
• Reduce ATE/CH4 slip
• Reduce Tube Wall Temperatures
• Reduce carbon formation potential
• Optimize catalyst loading even further

13. Primary Reformer Re-Tube
 By re-tubing reformer can generate
large benefits
• Reduce pressure drop by 20%
• Improve radiant efficiency
• Reduce tube wall temperature
• Increased plant rate by 3.5%
• Further optimize catalyst loading to
generate even more benefits

14. Combustion Air Pre-heat
 Installed on many modern plants
 Has been retrofitted to many plants
 Must have high stack temperature
 Allows for large improvements in radiant
efficiency
• Use less fuel
 Can allow for plant increases
 Will increase NOx levels
• May require NOx reduction system

15. Options for Secondary Reformers
 Install High Intensity
Burner Gun
 Install improved
catalyst
• Reduce installed
volume - up to 45%
• Increase mixing volume
 Add excess process air
• Requires H2 recovery in
loop

16. VULCAN SG Delta Retrofit for Shift
Vessels
 By installing a specialized support
system we can reduce pressure drop
significantly
 GBHE can offer the VULCAN SG Delta
which can reduce pressure drop by 50%
 Allows plant rate increases of up to
0.5%

17. CO2 Removal Retrofits
 Can uprate CO2 removal by
• Changing packing
• Use more efficient solution
 Either will help to reduce reboiler duties
• In turn allows reduction in steam to carbon
ratio
 GBH Enterprises range of catalysts are
designed to operate under these lower
steam to carbon conditions

18. Water Removal from Synthesis
Gas
 Use either molecular sieves or ammonia
washing
 Can feed synthesis gas to converter inlet
• Reduces ammonia content of gas inlet
converter therefore increases production
• Reduced refrigeration load
• No loss of reactants in purge gas

19. Converter Retrofits
 Convert to axial-radial or radial flow
 Utilize smaller catalyst
• Since reaction is diffusion limited
increases reaction rate and therefore
increased production
• Can improve efficiency by 0.5-1.0 GJ/t
• Must look at rest of plant
 Converter exit piping and exchangers

20. Converter Retrofits
 Often link with modifications to circulator
• Reduce circulation rate and hence power
requirement
 If converter already modified then can
• Modify converter again
 Use heat exchange rather than quench
• Install high activity catalyst
 VULCAN Series VSG-A101 low pressure
synthesis
 Can be utilized up to 150 bara

21. Converter Retrofits
 Further Options
• Add a booster converter
 Utilize when main converter has reached limit
 Can achieve up to 30% capacity increases
 Will need modifications to rest of the plant
• Add a synthesis gas converter - for example as
done in the Uhde DPUP
 Utilize when main converter has reached limit
 Can achieve up to 30% capacity increases
 Will need modifications to rest of the plant

22. Hydrogen Recovery
 Can increase plant capacity by up to 5%
with no other modifications
 Either
• Cryogenic
• Membrane
 If adding excess air to the secondary then
must install hydrogen recovery
• Even greater capacity increases are achievable
since methane slip has been reduced

23. Other Retrofits
 Addition of Saturator
 Fuel gas preheat
 Synthesis gas machine suction
chilling
 Modification of synthesis gas
machine internals
 Install AGHR in parallel to existing
Waste Heat Boiler
 Upgrade utilities

24. Other Options
 There are other options
 There are a number of operational
modifications that will improve plant
performance for no cost
• Reduction in steam to carbon
• Raising primary exit temperature
• Reduce excess air/oxygen in reformer
 Energy Audits will help to identify these
areas and the benefits of changing
process parameters

25. Plant Revamp Selector
Ammonia – Capacity Increases
What capacity
increase is required ?
>15%
Front End
Catalyst change
Re-tube
New burner gun
VULCAN SG Delta
<5%
Front End
SC Reduction
Pre-reformer
5-15%
Compression/Loop
Syn gas drying
High activity catalyst
H2 recovery
Chill Syn Gas
Front End
Parallel AGHR
Re-tube
Loop
Booster converter
MUG converter

26. Plant Revamp Selector
Ammonia – Efficiency Improvements
What efficiency improvement
is required ?
>1 GJ/t<0.1 GJ/t
Front End
SC Reduction
Fuel preheat
CO2 solution change
Saturator
Chill syngas
0.1-1 GJ/t
Front End
Combustion air
preheat
None

27. Problems and Pitfalls
Contractor and Contract
 Must carefully select partners
• Must have domain knowledge
 Design and operations
• Must have correct tools
• Must be able to supply correct level of detail
for study
 Must select appropriate contract type
• LSTK or Reimbursable
• Both have advantages and disadvantages

28. Problems and Pitfalls
Modelling Capability
 Must use correct tools
 Model the whole plant using a
flowsheeting package
• Must include all unit operations
• Must develop a robust base case
• Must validate against plant data
• Must understand deviations
• Then develop the retrofit case

29. Problems and Pitfalls
Retrofit Details
 The customer and engineering contractor
must determine
• Precise scope for retrofit
• Responsibilities
• Key deliverables
• A detailed and consistent design basis
• Time scale and milestones
• Review schedules
 Summarize as Good Project Management

30. Problems and Pitfalls
Design Basis
 Engineering contractor must conduct on
site visit
• Must work with client
• Collect representative plant data
• Model and understand plant data
• Discuss discrepancies and eliminate
• Identify bottlenecks
• Identify opportunities for improvement
 These form the core of the design basis

31. Problems and Pitfalls
HAZOPs and Commissioning
 Must use systematic review method to highlight
potential problems with retrofit
• HAZOPs are a well proven system
• Requires time and buy in from all parties
• Results as good as quality of people !
 Retrofit will change plant parameters
• Must update PFDs and P&IDs
• Must update operating instructions
• Must take additional care during start up

32. What Can GBHE Catalysts Offer?
 GBHE Catalysts Process Technology has
developed a detailed flowsheeting package
 GBHE Modelling for AMMONIA includes
• Detailed primary reformer model
• Models for secondary reformers, shifts, methanation and
ammonia synthesis
• Can model in detail the synthesis gas machine
 Unified, consistent and intelligent process
model

33. What Can GBHE Catalyst Process
Technology Offer?
 Detail catalyst unit operation models such as the
Industry leading VULCAN REFSIM program
• Also models for other catalyst unit operations
 Detail non-catalyst unit operation models such as
• Heat exchange programs
• Finite Element Analysis
• CFD modelling
 One stop shop

34. What Can GBHE Catalysts
Offer?
 Domain Knowledge
• Operations
 Many staff have operations
background
 Troubleshooting clients plants
• Design
 Many staff have detailed
engineering background
 Engineers work on design daily
 Work with leading contractors
on front end and detailed
design issues
Catalysts
Consulting
Services
Domain
Knowledge

35. What Can GBHE Catalysts
Offer?
 Can supply any level of detail for
retrofit
 Scoping studies
• Front End
• What are the best options
 Front End Engineering
• Flowsheets and design of key components
 Detailed Engineering
• Design of all components of retrofit
 A one stop shop for all your revamp
requirements

36. One Stop Shop Case Study
Re-tube – Present Model
Plant
Operator
Concept
Engineer
Tube
Supplier
Catalyst
Vendor
Tube
Installer
Catalyst
Handler
No Communication
Detailed
Engineer

37. One Stop Shop Case Study
Re-tube – “One Stop Shop” Model
Plant
Operator
GBHE
Concept Engineer
Tube
Supplier
Tube
Installer
Catalyst
Handler
Detailed
Engineer
Seamless
Minimum Cost
Maximum Benefit

38. Case Study - How GBHE Works
 Strong position due to credibility from previous
work
 Uprate projects
• Feasibility Process Uprate study on Naphtha
115%, 130% or 150% cases
• FEEP (Front End Engineering Package, what
would be needed?)
 115% FEEP adopted
• Option evaluations and natural gas feed
conversion
 Followed by full Engineering Detail Design
 Also additional design work on Desulfurization
Design Study

39. Conclusions
 Many options for retrofitting an ammonia
plant
 Must select correct options based on
• Require capacity increase
• Present bottlenecks
 Must select the right contractor
 GBHE has all the right expertise and
knowledge to develop and design retrofits