1. New LNG Processes & LNG Chains
MIT/NTNU/StatoilHydro PhD Program
in Energy and Gas Technology
MIT, Boston/Cambridge, 2829 October 2008
New LNG Processes & LNG Chains
require new Design Methodologies
for Subambient Processes by
Paul I. Barton Truls Gundersen
Chemical Engineering Energy and Process Engineering
MIT, Boston NTNU, Trondheim
USA Norway
Paul I. Barton
& Truls Gundersen

2. Brief Outline Motivation Project Proposal History
Prior collaboration MIT/NTNU
Results so far
Publications
The Liquefied Energy Chain (LEC)
The ExPAnD Methodology
Combining Thermodynamics & Optimization
Optimization Formulations and Algorithms
Paul I. Barton
& Truls Gundersen

3. Motivation
Increased importance of Natural Gas and LNG in the World and in Norway
A Number of Current and Future Challenges in LNG (and Natural Gas)
Significant Limitations in Existing Design Methodologies and Tools for LNG and Subambient Processes
Paul I. Barton
& Truls Gundersen

4. Natural Gas increases in Importance
Coal
Oil
Paul I. Barton
& Truls Gundersen

5. LNG increases even more
Ref.:
Paul I. Barton
& Truls Gundersen

6. Challenges for the LNG Industry
New ways to utilize Stranded Natural Gas
Trend towards (flexible) Floating LNG Chains
Will need CCS from fossil based Energy Systems
Capturing CO2 will drastically change Heat/Power ratio
Future Large Scale use of Amines has a considerable Economic Penalty; it may have an Environmental Penalty
How to deal with larger H2S and CO2 fractions?
Could Cryogenic Distillation (Ryan-Holmes) be used?
Effects of breakthroughs in Equipment Design
Synergies in co-localization with Industrial Cluster
 Need new Process Concepts and Chain Configurations
Paul I. Barton
& Truls Gundersen

7. Limitations of Existing Methodologies
Pinch Analysis (PA) has been extensively used in the Process and Energy Industry for 25 years to Design:
Heat Exchanger Networks with focus on
Heat and Power Systems Energy Efficiency
Distillation Systems, etc. and Economy
Major Limitations of PA in Subambient Processes
Only Temperature is used as a Quality Parameter
Exergy Considerations are made through the Carnot Factor
Pressure and Composition are not Considered
Exergy Analysis and 2nd Law of Thermodynamics
Considers Temperature, Pressure and Composition
Focus on Equipment Units, not Flowsheet (Systems) Level
No strong Link between Exergy Losses and Cost
Often a Conflict between Exergy and Economy
Paul I. Barton
& Truls Gundersen

8. Why is Pressure important Subambient?
Pressure is significant in Process Integration efforts to reduce Energy Requirements above Ambient
Defines the Level ( T ) of large Heat Duties ( Q )
Often defines the Heat Recovery Pinch
Pressure is even more important below Ambient
In Phase changes, Temperature is linked to Pressure
In Pressure Changes, Temperature is linked to Power
Subambient Cooling (Refrigeration) is provided by Compression, thus Pressure is again important
Pressure can be ”traded” against Cooling
A pressurized Cold Stream below Ambient can be expanded to provide Additional Cooling (and some Power)
Pressure Exergy can be converted to Temperature Exergy
Paul I. Barton
& Truls Gundersen

9. Project Proposal
”Optimal Design of LNG Processes and Production Chains  Developing new Methodologies and Tools for Subambient Processes”  ( )
Supported by StatoilHydro (LoI)
Application pending with the RCN
Budget and Manpower
8 mill. NOK total over 3 years (1.3 mill. USD)
2 PhD’s (3 years) & 2 Post.doc’s (2 years)
Existing Groups & Related Topics
Paul I. Barton & 2 PhD’s (A. Selot & E. Armagan)
Truls Gundersen & 2 PhD’s (A. Aspelund & R. Anantharaman)
Research Strategy: Simultaneous Development of new Process Concepts and Design Methodologies
Paul I. Barton
& Truls Gundersen

10. History of Collaboration  Barton / Gundersen
Informal collaboration since 2005
Joint Project Proposal for the 1st Call MIT/NTNU October 2005
PhD Student Audun Aspelund at MIT Fall 2006 & Spring 2007
Four Results have emerged in Parallel
A Liquefied Energy Chain (LEC) for Stranded Natural Gas
An Extended Pinch Analysis and Design (ExPAnD) Procedure
A Math Progr. Model for Optimizing Temperatures and Pressures
A Simulation-Optimization Approach for Entire LNG Chains
Publications
1 Patent on the LEC (industrialization attempted through TTO)
Journal Papers:
1 published (ExPAnD), 4 (series) accepted (LEC), 1 drafted (Opt. P/T)
Conference Contributions:
CHISA/PRES 2006, ESCAPE 2007, AIChE Mtg 2007, INFORMS 2007
1st Gas Symposium, Qatar, 2009 (2 papers accepted)
Paul I. Barton
& Truls Gundersen

11. The Liquefied Energy Chain (LEC) - Utilize Stranded Natural Gas for Power Production - Combined with CO2 Capture and Storage - Enhanced Oil Recovery using CO2 - Combined Liquid Carrier
OXYFUEL Process
LIN
LCO 2
LNG
The
Offshore
Process S t o r a g e
Onshore NG CO N
ASU
Power O
Argon
Water
Electricity
AIR
Paul I. Barton
& Truls Gundersen

12. The ExPAnD Methodology
Extended Pinch Analysis and Design
Currently focusing on Subambient Processes
A new Problem Definition has been introduced:
”Given a Set of Process Streams with a Supply and Target State (Temperature, Pressure and the resulting Phase), as well as Utilities for Heating and Cooling  Design a System of Heat Exchangers, Expanders and Compressors in such a way that the Irreversibilities (or later: TACs) are minimized”
Limitations of the Methodology (at present)
Relies Heavily on a Set of (10) Heuristics, 6 different Criteria (Guidelines) and suffers from a rather Qualitative Approach
Strong need for Graphical and/or Numerical Tools (Optimization) to replace or assist Heuristic Rules and Design Procedures
Using the Concept of Attainable Region is a small Contribution towards new Graphical and Quantitative ExPAnD Tools
Paul I. Barton
& Truls Gundersen

13. Temperature/Enthalpy (TQ) ”Route” from Supply to Target State is not fixed
The Route/Path from Supply to Target State is formed by Expansion & Heating as well as Compression & Cooling
a) Hot Streams may temporarily act as Cold Streams and vice versa
b) A (Cold) Process Stream may temporarily act as a Utility Stream
c) The Target State is often a Soft Specification (both T and p )
d) The Phase of a Stream can be changed by manipulating Pressure
The Problem is vastly more complex than traditional HENS
Paul I. Barton
& Truls Gundersen

14. How can we Play with Pressure?
Given a ”Cold” Stream with Ts = - 120ºC, Tt = 0ºC, ps = 5 bar, pt = 1 bar
Basic PA and the 2 ”extreme” Cases are given below:
Heating
before
Expansion
159.47ºC
Expansion
before
Heating
Heating
only ºC
Paul I. Barton
& Truls Gundersen

15. How can we Play with Pressure?
Given a ”Cold” Stream with Ts = - 120ºC, Tt = 0ºC, ps = 5 bar, pt = 1 bar
Attainable Region with One Expander:
Paul I. Barton
& Truls Gundersen

16. Sub-processes in the LEC
Oxyfuel
Power Plant
CO2
Liquefaction
Natural Gas
Air Separation
ASU NG
Air
LIN
LNG W
LCO2 O2
H2O
Illustrate how ExPAnD is used
to design the Offshore Process
Paul I. Barton
& Truls Gundersen

17. Base Case for the Offshore Process - using basic Pinch Analysis
Heat Recovery first,
Pressure Adjustments subsequently
Paul I. Barton
& Truls Gundersen

18. Base Case Composite Curves
Seawater
CO2 N2 NG
LNG
ex = 49.7 %
External Cooling required for Feasibility
External Heating is ”free” (Seawater)
Paul I. Barton
& Truls Gundersen

19. After several Process Modifications
ex = 85.7 %
The Composite Curves have been ”massaged”
by the use of Expansion and Compression
Paul I. Barton
& Truls Gundersen

20. A novel Offshore LNG ProcessK -
100 P
102 V
101 NG 2
LIQ
EXP 1 3 4 5 6
PURGE
LNG N 10 11 CO 9 8 12 7
Self-supported w.r.t. Power
& no flammable Refrigerants
Paul I. Barton
& Truls Gundersen

21. The Nitrogen ”Path”
Paul I. Barton
& Truls Gundersen

22. The Onshore Process (Regasification)
ex = 71.2 %
Paul I. Barton
& Truls Gundersen

23. More new Process Concepts?
The LNG Industry is facing several Challenges
We will Challenge established ”Truths” about LNG
The Trend has been to shift from Cascaded Single Component Refrigerants to Mixed Refrigerants
Cascade Liquefaction Processes
Mixed Refrigerants
Mixed Refrigerants cause Flow Distribution Problems in Heat Exchangers Onshore, even more so Offshore
We have shown that Multicomponent Behavior can be achieved by Single Components playing with Pressure
Expansion & Compression
Paul I. Barton
& Truls Gundersen

24. Cascade Liquefaction Process
Paul I. Barton
& Truls Gundersen

25. Combining Mixed and Pure Refrigerants
APCI’s C3-MR dominates (≈ 87%)
Paul I. Barton
& Truls Gundersen

26. Pure Refrigerants & Expansion/CompressionK -
100 P
102 V
101 NG 2
LIQ
EXP 1 3 4 5 6
PURGE
LNG N 10 11 CO 9 8 12 7
Paul I. Barton
& Truls Gundersen

27. Pure Refrigerants & Expansion/Compression
Q: Can these Results from the Offshore Process be utilized in Onshore LNG Applications ?
Paul I. Barton
& Truls Gundersen

28. Why do we need Optimization?
The Heuristics of ExPAnD coupled with Domain and Engineering Insight can produce Thermodynamically “sound” and “near-optimal” Processes, however . . .
Multiple Economic Trade-offs requires Optimization
Optimization can be used in a number of Ways
At the total Energy Chain Level (including Ship Utilization)
At the Level of the individual Processes of the Chain
Optimize Decisions at the Flowsheet Level (structure)
Optimize Operating Conditions (flows, compositions, P and T)
Different Optimization Algorithms can be used
Deterministic Methods (Mathematical Programming)
Stochastic Methods (Simulated Annealing, Genetic Algorithms, etc.)
Paul I. Barton
& Truls Gundersen

29. my Project Partner Prof. Paul I. Barton
and
by that
it is time
to introduce
my Project Partner
Prof. Paul I. Barton
Paul I. Barton
& Truls Gundersen

30. Paul I. Barton
& Truls Gundersen