Transcript Design of LNG Facilities

Evaluation of LNG
Production Technologies
Ayema Aduku
Oluwaseun Harris
Valerie Rivera
Miguel Bagajewicz
University of Oklahoma
Outline
LNG Background
 Objective
 Simulation Specifications
 Liquefaction Techniques
 Heat Exchanger Types
 Simulation Method
 Results

Flow Diagram for a Typical LNG Plant
LNG (Liquefied Natural Gas) Basics

Combustible mixture of hydrocarbons
 Dry
VS. Wet
NGL Extraction
 Dehydration/Scrubbing
 Liquefied Natural Gas

 Target
temperature for Natural gas:-260°F
 Reduces volume by a factor 600
Objective

Main Objectives
 Simulate Processes
 Optimize Processes
 Minimize compressor work
 Compare Processes based on
 Capital cost
 Energy cost
 Total cost per capacity(Ton)
Liquefaction Processes
Mixed Refrigerants
Pure Refrigerants
Both
Linde Process
CoP Simple Cascade
APCI C3 MR
Axens Liquefin Process
CoP Enhanced
Cascade
APCI AP-X
Dual Mixed Refrigerant
Linde 2006
Technip-TEALARC
ExxonMobil
Dual Multi-component
Black and Veatch Prico
Process
Technip- Snamprogetti
* Italicized processes signify Patent searched processes.
* Bolded processes signify processes not included in scope of project.
Other
BP Self refrigerated
process
ABB Randall TurboExpander
Williams Field
Services co.
Mustang Group
Flow diagrams
Black and
Veatch’s PRICO
Process
Axens Liquefin Process
C3MR: Air Products and
Chemical Inc
ExxonMobil Dual Multi-Component Cycle
AP-X: Air Products
and Chemical Inc.
Technip- TEALARC System
BP- Self
Refrigerated
Process
DMR- Dual Mixed Refrigerant
Linde/Statoil -Mixed Fluid Cascade Process
ConocoPhilips
Simple
Cascade
Linde- CO2 MFCP
Simulation Specifications

Natural Gas composition

Methane: 0.98
 Ethane: 0.01
 Propane: 0.01



Inlet conditions
 Pressure: 750 psia
 Temperature: 1000F
Outlet conditions
 Pressure: 14.7 psia
Beihai City, China
o
 Temperature: -260 F
Capacity: Common min. to max. capacity of process
 Common min. Capacity: 200,000 lbs/hr
Liquefaction Techniques

Different Liquefaction techniques include:
 Single
Refrigeration cycle
 Multiple Refrigeration cycles
 Self Refrigerated cycles
 Cascade Processes

The cooling of natural gas involves the use of
refrigerants which could either be pure component
refrigerants or mixed component refrigerants.
Liquefaction Techniques
Schematic of a Simple Refrigeration Cycle
Compressor
Expander
Heat Exchanger
Liquefaction Techniques


Mixed refrigerants are mainly composed of
hydrocarbons ranging from methane to pentane,
Nitrogen and CO2.
Pure component Refrigerants
 Specific

operating ranges for each component
Mixed Refrigerants
 Modified
to meet specific cooling demands.
 Helps improve the process efficiency
Liquefaction Techniques
T-Q Diagrams
Natural gas cooling
curve
Area between curves
represents work
done by the system
Liquefaction Techniques
Single Refrigeration Cycle
 One
refrigeration loop that cools the natural
gas to its required temperature range.
 Usually requires fewer equipment and can
only handle small base loads.
 Lower capital costs and a higher operating
efficiency
Black and Veatch:
PRICO Process
Condenser

Compressor
Inlet Gas

100oC

Cold Box
Residue
-260oC
Expander
LNG

Single mixed refrigerant
loop and single
compression system
Limited capacity (1.3
MTPA)
Low capital cost
Great Pilot Process
Refrigeration Cycles and Natural
Gas Liquefaction
Compressor
Inlet Gas
Simple Refrigeration Cycle
Cold Box
LNG
Black and Veatch- PRICO Process
Liquefaction Techniques
Multiple Refrigeration cycles
 Contains
two or more refrigeration cycles.
Refrigerants involved could be a combination
of mixed or pure component refrigerants.
 Some cycles are setup primarily to
supplement cooling of the other refrigerants
before cooling the natural gas.
 More equipment usually involved to handle
larger base loads.
Air Products and Chemical Inc:
C3-MR
LNG



Inlet Gas

Mixed Refrigerant
APCI processes are used
in almost 90% of the
industry
Good standard by which to
judge the other processes
Capacity of about 5 MTPA
Utilizes Propane (C3) and
Mixed Refrigerants (MR)
Liquefaction Techniques
Self Refrigerated Cycles
 Takes
advantage of the cooling ability of
hydrocarbons available in the natural gas to
help in the liquefaction process.
 Numerous expansion stages are required to
achieve desired temperatures.
 Considered as a safer method because there
are no external refrigerants needing storage.
BP Self Refrigerated Process


Residue Gas


Inlet gas
LNG
Neither refrigerants,
compressor, nor expanders
present in setup.
Cost include mainly capital
costs and electricity.
Low Production rate (51%)
Capacities of over 1.3MTPA
attainable .
Liquefaction Techniques
Cascade Processes
A
series of heat exchangers with each stage
using a different refrigerant.
 Tailored to take advantage of different
thermodynamic properties of the refrigerants
to be used.
 Usually have high capital costs and can
handle very large base loads.
ConocoPhilips Simple Cascade

3 stage pure refrigerant
process

Propane
 Ethylene
 Methane
Methane
Ethylene
Propane
Residue Gas

Sub-Cooling
Inlet Gas
Pre- Cooling Liquefaction
LNG
5 MTPA Capacity
Equipment
Plate Fin Heat Exchanger
Spiral Wound Heat Exchanger
Spiral Wound Heat Exchanger
Equipment Comparison
Plate-Fin-Heat-Exchangers
Coil-Wound-Heat-Exchangers
Extremely compact
Compact
Multiple streams
Multiple streams
Single and two-phase streams
Single and two-phase streams
Fluid
Very clean
Clean
Flow-types
Counter-flow
Cross counter-flow
Characteristics
Cross-flow
Heating-surface
300 - 1400 m²/m³
20 - 300 m²/m³
Materials
Aluminum
Aluminum
Stainless steel (SS)
Carbon steel (CS)
Special alloys
Temperatures
-269°C to +65 °C (150 °F)
All
Pressures
Up to 115 bar (1660 psi)
Up to 250 bar (3625 psi)
Applications
Cryogenic plants
Also for corrosive fluids
Non-corrosive fluids
Also for thermal shocks
Very limited installation space
Also for higher temperatures
Our Evaluation Methods




Data on operating conditions (Temperatures,
Pressures, Flowrates, etc) for all these
processes is not widely available (Only
some is reported).
We decided to perform simulations using our
best estimates.
We used minimum compression work as
guide.
We identified non-improvable points
Details of methodology





Conditions after each stage of refrigeration were noted
After making simple simulations mimic real process,
variables were transferred to real process simulation
Optimization- Refrigerant composition
Optimization- Compressor work
Restriction needed- Heat transfer area


Restriction needed- Second law of thermodynamics


All cells in LNG HX must have equal area
Check temperature of streams
Utilities

Obtain cooling water flow rate
CO2 Pre-cooled
Linde Process


Inlet Gas
100oC

Pre- Cooling

-70oC
Liquefaction
-140oC
Sub-Cooling
-260oC
LNG
High
Pressure

Low
Pressure

Modification of the Mixed Fluid
Cascade Process
Three distinct stages using 3
mixed refrigerants with different
compositions
Carbon dioxide is sole refrigerant
in pre-cooling stage
Separate cycles and mixed
refrigerants help in the flexibility
and thermodynamic efficiency
Process is safer because
hydrocarbon inventory is less
8 MTPA Capacity
Results
Cost Basis




Economic Life of 20 years
New train required at the documented
maximum capacity of each specific process.
Average cost of electricity and cooling water
throughout the US used in analysis.
Energy cost evaluated at a minimum capacity
of 1.2 MTPA
Results
10
Results
10
Results
Process
Prico
Liquefin
ExxonMobil
DMR
APX
MFCP
MFCP(CO2)
TEALARC
C3MR
Conoco
Cost per ton ($)
5.12
3.41
4.83
12.58
19.20
31.73
24.77
25.35
12.93
20.15
Max capacity (MTPA)
1.20
6.00
4.80
4.80
7.80
7.20
7.20
6.00
4.80
5.00
Analysis

Our results may not match market trends
 Operating
temperature and pressure range
as well as flowrate information unavailable
 Precedents to compare results unavailable
 Information on cost to use process
unavailable (licensing, proprietary
production fees, etc.)
Analysis

We may be trapped in local minima and failed
to identify better conditions
Work
Local Minimum
Global Minimum
Temperature
Conclusions




We successfully simulated several LNG
production plants
We obtained capital and operating costs and
determined a ranking
Some connection with existing trends were
identified, but other results do not coincide with
market trends
We discussed why discrepancies may arise.
Questions?
References








"Overview: LNG Basics." Center for Liquefied Natural Gas. 2008. Center for Liquefied Natural
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www.fpweb.com/200/Issue/Article/False/67449/Issue
Fossil Energy Office of Communications. U.S. Department of Energy: Fossil Energy. 18 Dec
2007. U.S. Department of Energy. 3 Feb 2008.
.<http://www.fossil.energy.gov/programs/oilgas/storage/index.html>.
"Mustang receives U.S. patent for LNG liquefaction process." Scandanavian Oil and Gas
Magazine. 14 Dec 2007. 3 Feb 2008. <http://www.scandoil.com/moxie-bm2/news/mustangreceives-us-patent-for-lng-liquefaction-pr.shtml>.
Spilsbury, Chris; Yu-Nan Liu; et al. "Evolution of Liquefaction Technology for today's LNG
business." Journees Scientifiques Et Techniques (2006)
Process Selection is Critical to onshore LNG economics.” World-Oil Magazine. February 2006
com
<http://www.worldoil.com/Magazine/MAGAZINE_DETAIL.asp?ART_ID=2808&MONTH_YEAR=F
eb-2006>
Flynn, Thomas N. “Cryogenic Engineering.” Second edition. Marcel Dekker. New York- NY.
2005