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lng fundamental presentation
Citation preview
1 -
TPG 4140 Natural Gas - 2013
LNG –
fundamental principles and plant examples
Jostein Pettersen
2 -
Outline
• Why LNG?
• What is LNG ?
• Block diagram
• Gas pre-treatment
• Gas liquefaction
− Some basics
− Process alternatives
• LNG storage and loading
• LNG transport
• LNG plant examples
− Focus on Hammerfest LNG / Snøhvit
3 -
Why produce LNG?
LNG is mainly produced for transportation purposes • When the gas market is far from the source of the natural gas it
can be more economical to transport the gas as LNG instead of in a natural
gas pipeline.
• LNG also offers greater flexibility than pipeline gas
4 -
LNG Density
Natural gas
LNG
1 m3 LNG corresponds
to ca 600 Sm3 natural gas
S = Standard state, 15C, 1 atm
At temperatures above -110 ºC
LNG vapour is lighter than air
LNG is lighter than water
LNG Density: 450 kg/m3
Water density: 1000 kg/m3
5 -
Types of liquefaction plants
• Base-load plants
Large plants which are directly based on a specific gas field development and are the main plants for handling the gas. A base-load plant has typically a production capacity of above 3 Mtpa (million tons per annum) of LNG (i.e. . The main world-wide LNG production capacity come from this type of plants
• Peak-shaving plants
Smaller plants that are connected to a gas network. During the period of the year when gas demand is low, natural gas is liquefied and LNG is stored. LNG is vaporized during short periods when gas demand is high. These plants have a relatively small liquefaction capacity (as 200 tons/day – ca 70 ktpa) and large storage and vaporization capacity (as 6000 tons/day). Especially in the US many such plants exist
• Small-scale plants
Small-scale plants are plants that are connected to a gas network for continuous LNG production in a smaller scale. The LNG is distributed by LNG trucks or small LNG carriers to various customers with a small to moderate need of energy or fuel. This type of LNG plants typically has a production capacity below 500 ktpa. In Norway and China several plants
within this category is in operation.
© 2013, IHS Inc. No portion of this presentation may be reproduced, reused, or otherwise distributed in any form without prior written consent.
LNG global base load liquefaction plants (2013)
6
Source: IHS CERA.
00406-6_2808
7 -
Block diagram
Gas processing
8 -
Simplified LNG plant block diagram
End
flash
HHC
Extraction
CH4/N2
Fuel
gas
Power
&
heat
(C5+) (C4 and C3)
(CO2 and H2S)
9 - 2010-09-26
Gas conditioning (pre-treatment)
• Acid Gas (CO2 and H2S) removal
− Acid gas causes corrosion, reduces heating value, and may freeze and create solids in
cryogenic process
− Typical requirements for LNG: Max 50 ppmv CO2, Max 4 ppmv H2S (ppmv - parts per million by volume)
− Usual process: aMDEA (Amine)
• Dehydration (water removal)
− Water will freeze in cryogenic process
− Typical requirement: Max 1 ppmw (weight) H2O (In some cases max 0.1 ppmw)
− Usual process: Adsorption (Mol sieve)
• Mercury removal
− Mercury can cause corrosion problems, especially in aluminium heat exchangers
− Requirement: Max 0.01 g/Nm3
− Usual process: Adsorption
10 -
Liquefaction process
11 - 2010-09-26
Example of natural gas path through liquefaction
pressure-enthalpy diagram (C1:89.7% C2:5,5% C3:1.8% N2:2.8%)
1
10
100
-900 -800 -700 -600 -500 -400 -300 -200 -100 0 100 200
Enthalpy [kJ/kg]
Pre
ssu
re [
bara
]
Crit
Phase
X=0.80/0.20
X=0.60/0.40
t=-200.0
t=-150.0
t=-100.0
t=-50.0
t=0.0
t=50.0
s=-4.000
s=-3.000
s=-2.000
s=-1.000
s=0.000
-200oC -150oC -100oC t = -50oC 0oC 50oC
Precooling Liquefaction Subcooling
Expansion
JT Throttling
End flash LNG
s = constant
12 -
Vapour pressure of pure fluids relevant for LNG
processes
1
10
100
-200 -150 -100 -50 0 50
Pre
ssu
ra(B
ara
)
Temp(C)
Refrigerant Vapour Pressure
N2
C1
C2
C3
NC4
Ethylene
LNG Range
N2 C1 Ethylene
C2
C3
n-C4
13 -
Liquefaction process licensors – Base load LNG plants (3+ Mtpa)
• Air Products and Chemicals Inc. (APCI)
− World leader since since the 1970s – ca 80 operating trains
− Propane Precooled Mixed Refrigerant (C3MR) process dominates
− AP-XTM (QatarGas II, III and IV, RasGas III: Six trains of 7.8 Mtpa each, Start up 2008)
• ConocoPhillips (Optimised) Cascade
− Alaska: Kenai (Operating since 1969!)
− Trinidad: Atlantic LNG - 4 trains
− Egypt: Idku – 2 trains
− Australia: Darwin LNG – 1 train
− Equatorial Guinea – 1 train
− Angola – 1 train
• Shell DMR – Double Mixed Refrigerant (Sakhalin, 2 x 4.8 Mtpa – start-up 2007) PMR (same as C3MR – but parallel MR circuits) – no references
• Linde MFC® Mixed Fluid Cascade Process (Snøhvit, 4.3 Mtpa – start up 2007)
Liquefaction process selection (Source: M. Nored, Apache Corp, 2013)
14 - 2010-09-26
C3MR
15 -
Simplified cascade process for natural gas
liquefaction
Methane
Ethylene
Propane
NG 12 °C -32 °C
1.4 bar 7 bar
-96 °C
1.4 bar 19 bar
LNG -155 °C
1.4 bar 45 bar
16 -
Temperature stages in cascade process
17 - 2010-09-26
Example of single-mix refrigerant cycle for natural
gas liquefaction (Prico cycle) (Max 1.2 Mtpa)
LNG
NG
5 bar
30 bar
12 °C
-155 °C
12 °C
-155 °C -155,5 °C
6,5 °C
99,8 °C
Composition:
NG Refrig
C1 0.897 0.360
C2 0.055 0.280
C3 0.018 0.110
nC4 0.001 0.150
N2 0.028 0.100
18 - 2010-09-26
Temperature – enthalpy diagram of Prico example
-200
-150
-100
-50
0
50
100
150
-1500 -1000 -500 0 500 1000 1500
Enthalpy, x 10^6 kJ/hr
Tem
pera
ture
, C
NG
Mixed refrigerant
NG 60 bar
LNG
NG
5 bar
30 bar
12 °C
-155 °C
12 °C
-155 °C -155,5 °C
6,5 °C
99,8 °C
Propane precooled mixed refrigerant (C3MR)
(Air Products and Chemicals Inc. - APCI) Illustration
from CB&I
19
Compressor driver selection (Source: M. Nored, Apache Corp, 2013)
20 - 2010-09-26
Industrial
gas turbines
21 - 2010-09-26
LNG storage and
loading
22 - 2010-09-26
LNG tank containment principles
23 - 2010-09-26
• Pre-stressed concrete outer walls
constructed by slipforming, sheathed
internally with a gas-tight layer of
nickel-alloyed steel.
• Inner tank in nickel-alloyed steel,
separated from the outer walls by a
layer of perlite - a variety of volcanic
obsidian highly suitable for insulation
• Extra layer of steel and insulation at
the transition between outer wall and
tank bottom to protect it against
strong local stresses should the
inner tank begin to leak.
• Heating cables under the tanks will
ensure that the ground remains
above 0°C in order to prevent frost
heaving.
Example of full-containment LNG tank design
24 - 2010-09-26
Typical storage and loading system
Loading arms connected
25 - 2010-09-26
26 -
LNG ships
27 -
LNG transportation – technical aspects
• LNG is transported at – 163 deg. C and at atmospheric pressure
• This low temperature require that the LNG is transported and handled with special
consideration, i.e.
− Completely separated from the ship’s hull
− LNG temperature must be maintained during the voyage – requiring efficient insulation
of the cargo tanks and handling of boil off gas (BOG)
− All cargo handling equipment must be able to operate at the low temperature of -163
deg. C
• Two basically different cargo containment systems are used:
− Self supported independent tanks (Moss Rosenberg spherical tanks, IHI SPB,
cylindrical tanks)
− Membrane tanks (Gaz Transport and Technigaz (GTT))
• Market share between the two concepts has been about. 50/50 - but the membrane concept
has been increasingly selected for recent newbuilding orders.
Cargo containment systems
Spherical tanks
(Moss Rosenberg) Membrane containment
28 -
29 - 2010-09-26
Plant examples:
- Trinidad – Atlantic LNG
- Darwin LNG (Australia)
- Yemen LNG
- Hammerfest LNG / Snøhvit
Atlantic LNG - Trinidad
30
Air cooled
condensers
Compressors
Jetty
Jetty
Cold boxes
(Heat exchangers) Source: www.comenco.it
Darwin LNG (Australia)
31
Source: www.lngfacts.org
Yemen LNG Water cooled
32
Sources:
www.yemenlng.com
www.yemenfox.net
www.nationalyemen.com
70°39′48″N
23°40′55″E
Facts:
Discovered: 1981 – 84
Water depth: 250 – 340 m
Distance to shore: 140 km
Gas in place (GIP): 317 GSm3
Recoverable reserves : 193 GSm3
Condensate: 34 MSm3
Statoil ASA (Operator) 36.79%
Petoro AS 30.00%
Total E&P Norge AS 18.40%
GDF Suez Norge AS 12.00%
RWE Dea Norge AS 2.81%
0 100 200 km
G:\T&P\ANT\MBM\NKG\Mapdata\NO\Norge_Oversikt\Lisenskart\Mxd\Statoil_Hydro_let_lic_tot_20070401vle.mxd
Snøhvit, Albatross
and Askeladd
Owners:
Original 2002
figures
2010-09-26
Hammerfest – Melkøya (May 2006)
2010-09-26
SNØHVIT Simplified overview
CO2 Injection
well
Production well
Seabed
Reservoir
Albatross
Production wells
CDU
Plem
Production wells
Production wells
Snøhvit
CO2 Injection well
Slug catcher Inlet facilities
Pretreatment
Fractionation
Carbon dioxide
MEG
recovery
Condensate production
LPG production
LNG production
Liquefaction cycle Subcooling cycle
Storage and loading:
LNG, LPG, condensate
Precooling cycle
Prepared by Petrolink as
Natural gas Cold Box
Nitrogen Removal Cold Box
Process substation
Electric power generation
Compressor area
Process area
2 3
1
HAMMERFEST LNG – Process area
Mixed Fluid Cascade (MFC®) Liquefaction process and
power/heat generation at Hammerfest
65 MW
65 MW
32 MW
NGL
2010-09-26
Why this very large extent of
prefabrication?
• Harsh weather conditions
• Remoteness – lack of necessary infrastructure
• Reduce the necessity of steel work at site
• Higher productivity at construction yard
• Reduce work at site in general -
of the total estimate of 15 million man-hours to
build the plant, 50 % is done at site.
Prefabrication and use of
large modules
Cold box
Process
plant
Prefabrication – LNG plant on a barge
Process systems on the barge Weight: 21.000 tonnes Height over deck: 60 m
Barge Weight: 10.000 tonnes Size: 154 x 54 x 9m
Blue Marlin and process barge in Cadiz….
Hammerfest – here we are!
In-docking of process-barge….
21 August 2007: Production start
13.09.07 First LNG to tank
26.09.07 First condensate cargo
20.10.07 First LNG cargo
47 - 2010-09-26
Arctic Shipping