This document discusses hydrogen management challenges for refineries aiming to produce cleaner fuels. It notes that hydrogen availability will be a key concern due to lower sulfur limits requiring more hydrogen consuming processes. The document presents various approaches refineries take to plan for hydrogen needs, including establishing future hydrogen demand and balances. It also discusses opportunities to optimize hydrogen systems through deeper analysis, modeling, and targeting purification and reuse opportunities rather than just increasing hydrogen production. This can help reduce capital costs for hydrogen investments.

1. REFINERY HYDROGEN MANAGEMENT
AspenTech Ltd
Indian Clean Fuels
Presented at Auto Fuels Quality :Towards Clean Environment organized by ISPe in 2002

2. Why is hydrogen an issue?
 Hydrogen Availability will be a Key Concern
 Clean fuels regulations
 Lower sulphur limits in diesel and gasoline
 Often, reformer is only producer of hydrogen
 Many Refiners Thinking about Outline Plans for Compliance
 Have reactor H2 chemical consumption estimates from catalyst vendors
 Preliminary designs from licensors
 Future hydrogen balances show need for investment in purification and/or
production facilities
 Investment Justified as « Stay-in-Business » decision
 No return on investment
 Main focus on minimising capital invested

3. Typical Approach to Clean Fuels
Establish H2
Select future H2
demand for new
purity for each
and revamped
process unit
units (Nm³/m³)
Yes
Prepare current Establish future Size new SMR / Submit for
OK?
site H2 balance site H2 balance H2 import capital approval
Look for obvious re-use No
and purification
opportunities
Is this the optimum approach?

4. Early Case Study: Far East Refinery
 Expansion Plan
 Major Expansion on Large Refinery Complex
 20% Capacity Increase in Existing Units
 Addition of New Lube Oil Plant (includes New Hydrogen Consumers)
 Implications
 Increase in Total Hydrogen Requirement by 50 MMSCFD (56 000
NM3/Hr)
 New Hydrogen Plant, Capacity 35 MMSCFD (39 000 NM3/Hr)
 Increase in Loss of Hydrogen-rich Gas to Fuel Header by 30 MMSCFD
(33 500 NM3/Hr) (Existing PSA Unit Bottlenecked)

5. Far East Refinery: Project Results
REDUCED CAPEX AND OPEX WITH
PURIFICATION

6. Hidden Opportunities
Optimise purity
Establish H2 and pressure
Select future H2
demand for new
purity for each
and revamped
process unit
units (Nm³/m³)
Yes
Prepare current Establish future Size new SMR / Submit for
OK?
site H2 balance site H2 balance H2 import capital approval
Deeper Look for obvious re-use No
Analysis Modeling and purification
opportunities
Systematic
Methodology

7. Hidden Opportunities
Optimise purity
Establish H2 and pressure
Select future H2
demand for new
purity for each
and revamped
process unit
units (Nm³/m³)
Yes
Prepare current Establish future Size new SMR / Submit for
OK?
site H2 balance site H2 balance H2 import capital approval
Deeper Look for obvious re-use No
Analysis Modeling and purification
opportunities
Systematic
Methodology

8. Hydrogen Balance

9. Detailed Analysis of Current Hydrogen Use
 All of our studies have identified operating (no cost) savings greater than the cost
of the study
 open valve on hydrogen line to flare
 open valve on hydrogen line to empty reactor
 bypassing on feed line to LPG recovery unit (twice)
 compression of hydrogen gas followed by direct letdown
 reduction in reactor pressure for yield improvement
 Detailed analysis also identifies direct letdowns to fuel (normally for pressure
control)
 Perform flowmeter corrections (incl. MW) and reconcile balance

10. US Refinery: Hydrogen header control
DHT Imported H2 flow manually
Imported H2 controlled
Catalytic H2
Reformer #1 Arosat
H2 H.P. Header
Catalytic Booster Naphtha HT #1 Make-up
Reformer #2 Compressors (4) Compressor
Let-downs to control header
pressure
H2
Absorber #2 Make-up
Compressor
Claus L.P. Header
TGTU
• Combination of 2 plants
Purge Gas FCC pretreater
• H2 consumed equals (roughly) H2 reactors
produced by cat. reformers Fuel Gas
• Large H2 import, large purge to control
header pressures Flare

11. US Refinery: Buffer Flow to Fuel Gas
MMSCFD
6
4
2
Year 2000
Median = 4.2 MMSCFD

12. US Refinery: Low-Cost Opportunities: Repiping + APC
Model-predictive controller to
DHT stabilize header pressure, reduce
purge to fuel
Imported H2
Catalytic H2
Reformer #1 Arosat
H2
Catalytic Booster Naphtha HT #1 Make-up
Reformer #2 Compressors (4) Compressor
H2
Absorber #2 Make-up
Compressor
FCC pretreater
Purge Gas
reactors
Fuel Gas
Annual Benefit:
Flare
$1 800 000 Re-route Arosat A Claus TGTU
purge gas to TGTU

13. Design Margin – Capital Avoidance
 By closing the current hydrogen balance, you reduce the “unconscious”
over-design in the future case
 One refiner had 15% hydrogen “loss” in current operation
 included a 15% loss in future balance (which doubled absolute value
of loss)
 justified such a loss as a design margin for the new SMR
 SMR design basis also included a design margin for uncertainties in
future process demand
 Unnecessary added investment

14. Hidden Opportunities
Optimise purity
Establish H2 and pressure
Select future H2
demand for new
purity for each
and revamped
process unit
units (Nm³/m³)
Yes
Prepare current Establish future Size new SMR / Submit for
OK?
site H2 balance site H2 balance H2 import capital approval
Deeper Look for obvious re-use No
Analysis Modeling and purification
opportunities
Systematic
Methodology

15. Interactions with Licensor / Catalyst Vendor Designs
 In design basis for new and revamped units, hydrogen make-up purity normally
assumed to be:
 Cat reformer gas purity (existing units)
 High purity from PSA or SMR (new / revamped units)
 Our experience is that there is scope to optimise these purities as future
hydrogen network evolves:
 multiple tie-in points for recovered hydrogen and new production
 moving make-up from suction to discharge of existing compressors to
increase capacity
 increase purge rates if future supply less constrained
 can give CAPEX and OPEX savings

16. European Refinery: Proposed Project
Catalytic Reformer 99.99% H2
92 % H2
User User User New User
91 % H2
NHT User
Fuel Gas
90 % H2 Purification
Make-up
Unit
Purge
User DHT
Revamp
Liquid
Feed

17. European Refinery: Diesel Hydrotreater Revamp
Recycle gas compressor
at maximum capacity. Make-up
Account for this.
Purge
Liquid
Feed
Reactor size and
catalyst volume
dependent on H2
partial pressure

18. European Refinery: Optimised Project
Catalytic Reformer 99.99% H2
92 % H2
User User User New User
91 % H2
NHT User
Fuel Gas
90 % H2 Purification
Make-up
Unit
Purge
User HDS-3
Increases Gas-to-Oil Ratio
Increases H2 Partial Pressure
Liquid
Feed
Minimise Capital Investment

19. US Refinery: Benefits From Better Yields
Impact of increased makeup purity Impact on FCC:
on mild hydrocracker:  Lower SOx, lower product sulphur
 Higher H2 consumption  Higher conversion to gasoline
 Better distillate quality  Less Light Cycle Oil
 Longer catalyst cycles, or  Less coke on catalyst
higher feed rate, or  Ability to process more feed
higher feed endpoint, or  More light ends
greater conversion
HC FCC
(c: .. proen2002-04-16-cert.ppt – rev D - 15-apr-2002)

20. US Refinery: Increased Purity: Fixed Sulphur in FCC Feed
As makeup purity increases from 89% to 98%
 Recycle purity increases to 94%
 Product aromatics decrease from 19.5 to 17.9 wt%
 FCC conversion increases by 2.31 vol%
 Increased H2 requirement: 80 SCF/bbl
 Peak temperatures decrease by 4.5oF
• 60 day increase in catalyst cycle life (36 month basis)
 Potential increase in capacity and/or severity
• Capacity increase not included in overall benefit
Net Benefit: $ 1.25 MM per year
(c: .. proen2002-04-16-cert.ppt – rev D - 15-apr-2002)

21. Hidden Opportunities
Optimise purity
Establish H2 and pressure
Select future H2
demand for new
purity for each
and revamped
process unit
units (Nm³/m³)
Yes
Prepare current Establish future Size new SMR / Submit for
OK?
site H2 balance site H2 balance H2 import capital approval
Deeper Look for obvious re-use No
Analysis Modeling and purification
opportunities
Systematic
Methodology

22. Aspen Hydrogen Software
 Flowsheeting environment
 Simplified unit models for producers, consumers, purifiers, headers, compressors etc.
 Tune using plant data
 Why do we need?
 Modelling of hydrogen systems
 Data reconciliation
 Overall hydrogen balances
 Predicts effect of changes (e.g. scale-up/down, altering make-up, changing purge rate
etc.)
 Calculates parameters for pinch optimisation
 Future balances
 Does not change network structure

23. Hidden Opportunities
Optimise purity
Establish H2 and pressure
Select future H2
demand for new
purity for each
and revamped
process unit
units (Nm³/m³)
Yes
Prepare current Establish future Size new SMR / Submit for
OK?
site H2 balance site H2 balance H2 import capital approval
Deeper Look for obvious re-use No
Analysis Modeling and purification
opportunities
Systematic
Methodology

24. Hydrogen Pinch Analysis
 Pioneered at Department of Process Integration, UMIST
 Graphical targeting methodology
 Maximises re-use and recovery of hydrogen from off-gases
 AspenTech a founder member of research group
 First industrial implementation of this methodology carried out by AspenTech

25. Hydrogen Pinch
1
0.9
0.8
0.7
0.6
Purity (-)
0.5
0.4
0.3
0.2
0.1
0
0 50 100 150 200 250 300
Flowrate (MMscfd)

26. Base Case
Recycle
62 MMscfd
91%
Consumer Purge
A 8 MMscfd
Reactor inlet
80 MMscfd 91%
18 MMscfd 92.8%
99%
Hydrogen Fuel
plant
Production
40 MMscfd Recycle
22 MMscfd
98 MMscfd
99%
85%
Consumer Purge
B 2 MMscfd
Reactor inlet
120 MMscfd 85%
87.6%

27. Reconfigured
Recycle
62 MMscfd
91%
Consumer
Reactor inlet A
80 MMscfd
18 MMscfd 92.8%
99% Re-use
8 MMscfd
Hydrogen Fuel
plant 91%
Production
36.6 MMscfd Recycle
18.6 MMscfd 93.4 MMscfd
99% 85%
8.7% reduction!
Consumer Purge
B 6.6 MMscfd
Hydrogen to Reactor inlet
85%
reactor unchanged! 120 MMscfd
87.6%

28. Hydrogen Pinch Analysis
 An excellent visualisation tool, but has several strong limitations, e.g.
 Binary assumption
 No pressure/compressor considerations
 Unconstrained target unrealistic
 Very limited scope and objective functions
 UMIST Research and Development led by N Hallale from 1998-2001
 Major enhancements made at AspenTech 2001-2002
(c: .. proen2002-04-16-cert.ppt – rev D - 15-apr-2002)

29. New approach
Make-up hydrogen Recycle hydrogen H.P. Purge
Separator gas flow
Minimum
and compositions
hydrogen
(including hydrogen)
purity and G/O
vary
ratio at
reactor inlet
H.P Separator
L.P. Purge
Liquid feed
Reactor
L.P. Separator
Use Aspen models for
reactor and separators Liquid product

30. Our Approach: Uses Models for Optimisation
Objective fn: min/max?
CONSUMER WITH RECYCLE
Decision variables
Subject to constraints:
CONSUMER WITH RECYCLE
Transfer of important Pressure, purity etc.
model parameters
Aspen Hydrogen Base
Enhanced Pinch
Case model
Optimiser
CO N S U MER WI TH RECY CLE
Project ideas
Repipe, new purifier,
new compressor etc.
CO N S U MER WI TH RECY CLE

31. Light Ends and Fuel Gas Balances
 Past methods focused on hydrogen system only
 Impact of changes on amine treatment, LPG recovery, and fuel gas balance
rarely considered
 direct re-use of high pressure purges can impact on cold-box performance
(e.g expansion of HP gases)
 more hydro-treating leads to higher low pressure purge flows, that can
exceed amine treating and LPG recovery capacity
 hydrogen recovery upstream of LPG recovery facilities can debottleneck
throughput and increase recovery
 taking the hydrogen out of fuel gas may push you to firing limits (e.g max fuel
oil firing for emissions)
(c: .. proen2002-04-16-cert.ppt – rev D - 15-apr-2002)

32. US Refinery: Customer Derived Solution
H2 Catalytic
Plants Reformers
40 MMSCFD
Membrane 47 KNM/Hr
60 MMSCFD Hydrogen
71 KNM3/Hr Distribution
Network
Low Sulphur
Heavier Crude
Diesel
More Upgrading
HYDRO HYDRO
TREATERS CRACKERS
HYDROGEN USERS
15 MMSCFD
18 NM3/Hr
Bottlenecked
Stripper
Fuel Gas Network

33. US Refinery: AspenTech Results
H2 Catalytic
Plants Reformers
60 MMSCFD Hydrogen
71 KNM3/Hr Distribution
Network
100 MMSCFD
118 KNM3/Hr
HYDRO HYDRO
TREATERS CRACKERS
HYDROGEN USERS
x
Membrane Stripper
Fuel Gas Network
x
Savings: ~5 / ~10 millions US$/ yr

34. Our Experiences
 Time spent investigating the current hydrogen balance pays back
 identifies operating savings
 saves capital in “unconscious” over-design
 Make the best use of high purity hydrogen
 can optimise with reactor models
 AspenTech design methodologies do minimise capital investment
 avoid new compressors if at all possible
 Hydrogen isn’t the only consideration
 increases in LPG recovery can help justify investment in hydrogen purification

35. Strategic investment planning
“TOGETHER we define and implement the optimum path to the optimum solution”
Modify New catalysts in Complete FCC Install H2 DHT proj.
H2 network FCC pretreater and pretreater proj. compressor (max.
(improve re-use) DHT re-use)
Increase H2 import Eliminate H2
Reduce H2 purge import
Install New PSA
with APC
SRU Revamp New SMR
Membrane
SMR
Cryogenic (delay investment)
Low-sulfur
gasoline
ULSD
Now 1 2 3 4