Upload
gerard-b-hawkins
View
192
Download
5
Embed Size (px)
DESCRIPTION
This presentation highlights some of the retrofits that can be applied to Improve efficiency Increase production
Citation preview
Revamps for Ageing Hydrogen Plants
By Gerard B. Hawkins
Managing Director, CEO
Introduction
This presentation highlights some of the retrofits that can be applied to • Improve efficiency • Increase production
Safe
ty
Effic
ienc
y
Rel
iabi
lity
Thro
ughp
ut
Envi
ronm
ent
Introduction
For older hydrogen plants, efficiency is worse than for a modern plant
To maximize profit must improve either • Plant efficiency • Plant production rate
Site Circumstances
Hydrogen plants have a wide range of site circumstances
Is there value for steam on the site ? What are the downstream users ? What is the contract basis for the H2
supply When conducting a revamp these need
to be carefully considered GBHE is in a unique position to fully
understand these issues and design revamps accordingly
Plant Limitations
Need to address plant limitations, such as • Process side pressure drop • Maximum tube wall temperature • Coil design temperatures in duct • Steam balance • Fan capacity
Basis for Study
Old style plant with • Top Fired SMR - 500 tubes • Steam to carbon of 3.9 • Duct heat recovery is feed preheat and
steam raising • HTS • LTS • Wet CO2 system • Methanation
Plant Limitations
Three areas that can limit plant performance
SMR
Plant Limitations
Three areas that can limit plant performance
SMR
Convection Section
Plant Limitations
Three areas that can limit plant performance
SMR
Convection Section
Cooling, Shifts and CO2 Removal
Change Catalyst Shape and Size
By optimizing catalyst size can • Reduce pressure drop by up to 27% • Reduce carbon formation potential
By changing to VULCAN Series VSG-Z101 can • Reduce CH4 slip and increase production by
5% • Reduce Tube Wall Temperatures by 10°C • Reduce carbon formation potential • Reduce pressure drop by 29%
Reduce Steam to Carbon Ratio
By reducing SC ratio by 0.6 can • Reduce steam addition by 19 mtphr • Increase steam export by 9 mtphr • Reduce pressure drop by 23% • Reduce TWT by 14°C • Gain 5.3 GJ/mmSCF
Reduce Steam to Carbon Ratio
Or increase plant rate • Reduced DP • Gain 1.8 GJ/mmSCF • In some cases can increase rate above
base case But must be aware of
• Metal dusting of WHB • Increased potential for carbon
formation
Raise Outlet Reformer Temperature
Many operators run to a false tube wall or outlet header temperature
By analysis of reformer operation, this limitation can be eliminated
Improves production by 2-5% At margin loss of efficiency Some of this efficiency can be
recouped by other revamps
Rebalancing Firing
One Terraced Wall or Side Fired reformers, the firing can be rebalanced
Either improves efficiency or steam raising capacity on in some cases can increase rate
Parameter Units Case A Case B Case C Firing at Top % 50 40 60 Firing at Bottom % 50 60 40 Steam Export Mt/hr 0 -15 +11 Efficiency GJ/mmSCF 452 443 463
Reformer Re-tubes
The reformer tubes do have to be replaced and therefore have to be considered as a consumable
By replacing with an improve metallurgy, a thinner wall tube can be used
This provides a wide range of process and operability benefits
Reformer Re-tubes
Parameter Units Case A Base
Case B New Tubes
Case C Uprate
Tube material N/A HK40 HP Mod HP Mod Tube OD mm 114 114 114 Tube ID mm 84 96.4 96.4 Catalyst “P”
“P” “P” “P”
H2 Production mmSCF 100 101 109 Efficiency GJ/mmSCF 430 428 433
Addition of a Pre-Reformer MP Steam
Existing Reformer
Natural Gas
Synthesis Gas
Pre-reformer
New Reheat Coil
Addition of a Pre-Reformer To obtain maximum benefit requires
• Reheat of effluent - an achieve very high preheat and reheat temperature with latest generation of pre-reforming catalyst can recover more heat from duct and reduce furnace duty significantly
• Must model effect on duct to ensure that existing demands for heat are fulfilled (HP Steam Raising)
Can allow for efficiency improvements of up to 24 GJ/mmSCF
Or rate increases of up to 9%
Addition of an ATR
Existing
Reformer
NG Preheater NG/Steam Preheater
MUG Cooler
Oxygen Preheater
Steam Drum
MP Boiler
Natural Gas Make Up Gas
Condensate
Addition of an ATR or Secondary
Either in parallel (ATR) or in series (secondary) • Parallel ATR has less impact on the main
plant • Main plant can run when ATR off line
Can increase production rate by 22% • More can be achieved depending on plant
design Require an oxygen plant (9 mt/hr) Energy efficiency improved by 13
GJ/mmSCF
Addition of an AGHRPR
Can add a AGHR as a post reformer Reduces steam export capacity significantly Depending on plant design allows for plant
rate increases of between 20-40% Also potential energy efficiency gains
Steam
Hydrocarbon Feed HDS
Fuel
Steam Generation
and Superheating
Steam Generation
and Superheating
Combustion Air
Pre - heat Reformed Gas
Process
Additional gas + steam feed
Gas Heated Post - Reformer
Waste Heat Boiler
HDS Preheat
Mixed Feed Preheat
Addition of Saturator
Recovers low grade heat into the process Maximizes quality and quantity Up to 13 mt/hr of export steam can be
generated Link with CO2 solution change
Addition of a Saturator
MP Steam
Existing Reformer
Natural Gas
Synthesis Gas
Heater
Saturator
Combustion Air Preheat
Allows for improvement in heat recovery from the duct
Most suitable for top fired furnaces but can be applied to side fired furnaces • Cost is higher due to complexity of
ducting Will reduce fluegas flow and therefore heat
available in the duct - must model this carefully
Improve plant efficiency by 30 GJ/mmSCF Can allow for rate increase
VULCAN SG Delta Retrofit for Shift Vessels
By installing a specialized support system can reduce pressure drop significantly
GBHE can offer the VULCAN SG Delta which can reduce pressure drop by around 50%
Allows plant rate increases of up to 3%
Other Options
Use ROG or other streams as a feed Use low methanol LTS catalyst Preheat fuel Change CO2 solution Install quench upstream of LTS Reduction in excess air in reformer
Hydrogen Plant Revamp Capacity Increases
What capacity increase is required ?
>15%
Front End Catalyst size change VULCAN SG Delta SC Reduction LTS Quench
<5%
Front End Catalyst shape and size change Pre-reformer Re-tube Change reformer exit temperature
5-15% Front End ATR AGHRPR
Hydrogen Plant Revamp Efficiency Improvements
What efficiency improvement is required ?
>15 GJ/mmSCF <5 GJ/mmSCF
Front End ATR SC ratio change Fuel preheat Excess air optimisation
5-15 GJ/mmSCF Front End Pre-reformer Saturator CA preheat
Front End Optimised reformer catalyst loading Re-tube VULCAN SG Delta
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
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
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
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
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
What Can GBHE Catalysts Offer?
Detail catalyst unit operation models such as the world leading VULCAN REFORMER SIMULATION 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
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
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 your revamp requirements
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
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
Case Study How GBHE Catalysts 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
Conclusions
A number of retrofits have been presented that are suitable for application to hydrogen plants
They address all the key limitations that hydrogen plants typically suffer from
To take full benefit from some of these retrofits, others may also be required
GBHE Catalysts has all the right expertise and knowledge to develop and design retrofits