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
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
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)
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