World Scale Boil-Off Gas Reliquefaction
Heinz C. Bauer (speaker), Linde Engineering, Germany
Hans Mattsson (speaker), Siemens, Sweden
Sven-Erik Brink, Siemens, Germany
AIChE Spring Meeting
San Antonio, TX
April 28 – May 2, 2013
Biographies
After graduation at the Technical University Munich as PhD in Applied Physics, Dr Heinz Bauer
joined Linde Engineering 32 years ago. He worked in different positions in process design as
well as sales and marketing. His focus has been on all kind of cryogenic gas processing
including cracked gases, synthesis gas, refinery off-gases and of course natural gas. Presently
he is responsible as Vice President for technology of natural gas processing plants.
heinz.bauer@linde-le.com
Hans Mattsson graduated as Mechanical engineer at Chapman School Karlskrona Sweden
1974. He started in the gas turbine division in what was to become Siemens Industrial
Turbomachinery AB, in 1980. He has about 30 years of experience in gas and steam turbine
installation, leading different engineering teams. Currently senior technical advisor in the
Siemens Energy Oil & Gas, Industrial Power FEED group, for Oil & Gas projects.
hans.mattsson@siemens.com
Sven-Erik Brink graduated at the Technical University Brunswick in Mechanical-Engineering
with Turbo Machinery as Field of Specialization. He has been with the compressor division of
Siemens since 1986 in different positions in sales and marketing working in Germany, Asia
Pacific and the US. He has developed the BOG single shaft compressor product line - tandem
casing design with variable Inlet Guide Vane Unit (IGV) a heated Dry Gas Seal Carrier. Today he
is technical consultant for BOG compressors at Siemens AG, Energy Sector, Oil & Gas,
Compressor & Solutions.
sven.brink@siemens.com
Linde AG Engineering Division
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Outline
Introduction
Concept Selection and Optimization
Rotating Equipment
Conclusion
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Sources of Boil-Off Gas
Large LNG export terminals include an LNG tank farm with large
LNG tanks providing storage capacity of several hundred
thousand meters cubed. Low pressure gases at tank pressure
(about 100 to 200 mbarg) originate from several sources like
• Boil-off gas caused by heat ingress through the tank walls
and LNG pumps
• Flash gas generated in the run-down line between
liquefaction and storage
as well as during cool-down of warm send-out systems
• Ship return gas / displacement gas during ship loading
Total BOG flow rate for a 10 mtpa facility
Linde AG Engineering Division
~1,000 t/d
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Site Conditions
Relevant site parameters
•
•
•
•
•
fuel gas balance
capacity of the existing refrigeration systems
availability of natural gas as feed stock
distance between liquefaction trains and jetty/tank area
flare load especially during peak BOG generation
BOG reliquefaction (BOGR) will generate a high value product
starting from very favorable feed stock conditions, as the
absence of water, sour gas components and heavy
hydrocarbons in BOG simplifies cryogenic processing
significantly
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Outline
Introduction
Concept Selection and Optimization
Rotating Equipment
Conclusion
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Concept Selection
• a BOGR unit with 0.3 - 1.0 mtpa LNG is similar to a mid-scale
LNG plant
• most land based plants of this size use SMR technology with
~350 kWh/tLNG or 15 MW for 1000 t/d
• feed gas compression to >50 bar requires about the same
power as the refrigeration cycle
• the preferred cryogenic heat exchangers is a coil wound
heat exchanger (CWHE)
• the cost adder for a CWHE is more than offset by its superior
availability
• mechanical drive with gas turbines is the preferred choice
• electric motors should be considered, if power supply is
reliable and economically attractive
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Process Optimization
Base Case
— N2 stripper T
— LNG subcooler E3
— two casing EFG compressor C3
— unbalanced power
between C1 and C2
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Process Optimization
Optimized Case
— N2 flash drums D1 & D2
— no LNG sub-cooler required
— one casing EFG compressor C3
— balanced power
between C1 and C2
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Open Methane Cycle (DMR concept)
mixed refrigerant cooling
air cooling
Fuel
LNG
— compression
— cooling
— 1st expansion
— 2nd expansion
— recycle
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Fuel Gas Composition
Material Balance for N2
— limited amount of N2 in LNG
— GT's with high efficiency will
see high N2 content in fuel
N2 in Fuel Gas (mol%)
50
— max. 8 mol% N2 in BOG are
acceptable for state-of-theN2 content
art gas turbines
in BOG
40
30
8 mol%
6 mol%
20
4 mol%
2 mol%
10
0
25
30
35
40
45
Gas Turbine Efficiency (%)
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Outline
Introduction
Concept Selection and Optimization
Rotating Equipment
Conclusion
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N2 Tolerant Gas Turbine SGT-600/700/800
Annular combustor design
— premixed air and fuel as main gas
— pilot flame burns around main
flame for stabilization
— 18 3rd generation nozzles
(burners)
Average residence time in
burner mixing tube ~3-5 ms
Linde AG Engineering Division
18 burners
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N2 Tolerant Gas Turbine SGT-600/700/800
Wobbe Index increase
by 80% in 2 minutes
Operational flexibility
40
30
30
20
20
10
0
10
N2
NOx
LFP
Load
0
10
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Time [minutes]
40
50
Load [MW] and LFP [% of alarm level]
N2 concent [vol%] and NOx [ppm]
40
— DLE system can operate on fuel gas
with high inert gas
— stable combustion without
pulsations with up to 40 vol% N2
— emission performance achieved
independent of N2 content
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Boil-Off Gas Compressor (IGV's)
Adjustable inlet guide vanes
— direct online start-up possible
— compact design
— large turn-down
— low maintenance
— plenty of references
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Boil-Off Gas Compressor (Seal Carrier)
Heated dry gas seal carrier
— avoids thermal shocks (e.g. during start-up)
(yellow) Oil heated Seal Carrier
(green) Dry Gas Seal
— protects from low and high temperatures and
from rapid temperature fluctuations
— avoids condensate build-up
(red) 3D Impeller
(blue) Inlet Guide Vane Unit (IGV)
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Outline
Introduction
Concept Selection and Optimization
Rotating Equipment
Conclusion
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Marlin Project in Bintulu
• World-scale BOG reliquefaction has become reality
• Linde Engineering has successfully developed a new product
for the LNG industry
• Siemens contributed with innovative compressor and gas turbine designs,
which are proven in service and are highly respected worldwide
• The first plant, which is based on
this novel concept, is under
execution for Malaysia LNG
in Bintulu and is scheduled
for start-up in late 2014
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Thank you
for your attention.