Snøhvit LNG Project Concept Selection for Hammerfest LNG Plant

PROGRAMME
GASTECH 2OO2
Roy Scott Heiersted, Technology Manager, Statoil
Roy Scott Heiersted was awarded a Master of Science degree in 1968 from Division for
Refrigeration Technology at the Norwegian Institute of Technology. He has been involved in
LNG technology- and business development since he joined Statoil in 1984. In 1997 he was
appointed as Alliance Manager of the industrial technology alliance with Linde AG aiming at
developing LNG technology and cost effective project execution strategies. He presently holds
the position of Technology Manager in the Snøhvit LNG Project.
PROGRAMME
GASTECH 2002
Qatar 13-16 October 2002
Snøhvit LNG Project
Concept Selection for Hammerfest LNG Plant
Roy Scott Heiersted
Technology Manager
Snøhvit LNG Project, Statoil ASA, Norway
PROGRAMME
Snøhvit LNG Project
Consept Selection for Hammerfest LNG Plant
Roy Scott Heiersted, Statoil ASA
Summary
The Snøhvit license partners made their final commitment to commercialize the gas and condensate
reserves of the Snøhvit area in September 2001. The Norwegian Parliament approved the plan for
development and operation of the Snøhvit area in March 2002.
The Snøhvit LNG chain will be in operation from October 2006 and will be the first LNG base load
production in Europe. The capacity of the LNG chain is 4.3 mtpa in a single train. The capacity
selection is based on an overall risk assessment, including potential technology qualifications.
The selected energy system of the Hammerfest LNG Plant is based on aero-derivative gas turbines
delivering electric power and process heat. The selected electric transmission system is increasing
overall on-stream days per year compared with direct mechanical drive.
The evaluation and selection of licensed process technology for the natural gas liquefaction involved
initially three competitors. A short list of two was made for the final commercial and technical tender.
The Statoil-Linde proprietary MFCP, the Mixed Fluid Cascade Process, is selected.
The selected construction strategy is based on maximum prefabrication, comprising a fully equipped
process and utilities barge to be transported to site and, in operation, serving as permanent foundation.
The process barge will be fabricated in a European yard and transported to site on the Norwegian coast
of the Barents Sea.
1
Snøhvit LNG Development Project
The Snøhvit area value chain is a complex development and the preparatory work has been substantial.
The decision to commercialize the gas and condensate reserves is taken on a comprehensive technical
and commercial evaluation of the value chain from the reservoirs to the markets.
The reserves will be commercialized through a grass roots LNG development. The LNG plant will be
built in the vicinity of the city of Hammerfest, on the northernmost coastline of Norway.
Statoil is operator of the Snøhvit LNG Development Project, having the overall responsibility from
reservoir to marketing, securing focus and consistency in the entire value chain. The Snøhvit partners
are Statoil ASA, Petoro, Total Norge AS, Norsk Hydro Production AS, RWE-DEA Norge AS,
Amerada Hess Norge AS, Svenska Petroleum Exploration and Gaz de France Norge AS.
The Norwegian Parliament approved the formal plan for development and operation in March 2002.
The Snøhvit LNG chain will be in operation from October 2006. Snøhvit LNG Company will be the
first base load LNG producer in Europe with exports including Spain and USA.
Snøhvit area location and resources
The Snøhvit area is located at the Norwegian Continental Shelf at 71o North in the Tromsøflaket West
province of the Barents Sea. The gas fields are located 160 kilometres offshore in 300 to 350 meters
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PROGRAMME
water depth. The Snøhvit LNG chain will be the first infrastructure development in the northernmost
oil and gas province on the Norwegian Continental Shelf.
The gas and condensate resources were discovered in the early 1980s, and are located in three different
fields, Askeladd, Albatross and Snøhvit. All three fields is part of the Snøhvit LNG Development
Project. The resources in place are in excess of 300 billion cubic meters of gas and additionally 20
million cubic meters of condensate.
LNG market outlets
Snøhvit LNG Company has established sales contracts with the companies Iberdrola in Spain and El
Paso in USA. TotalFinaElf and Gas de France will take their own equity gas. From the Snøhvit area,
distances to markets are above 2000 n.miles to southern ports of Europe and above 4000 n.miles to the
US east coast. The LNG carriers' round trips are approximately 10 and 20 days.
Given the plant production capacity and the sales portfolio, the shipping operation will use four LNG
carriers with a capacity of 145 000 m3 each. The total LNG shipment will be 4.3 million tons of LNG
per year, which means departures of the world’s largest sized LNG carriers from the Hammerfest
terminal every 5 to 6 days.
2
The Statoil technology agenda
The Snøhvit area has always been considered a complex development, and has been used by Statoil
for benchmarking of technology development since the 1980s. Together with the business objectives,
there has been a long-term commitment in Research and Development:
•
•
•
20 years of multiphase technology
15 years of sub-sea production systems
15 years of LNG technology.
Step-by-step, the technology achievements of sub-sea production and multiphase transportation have
been implemented in North Sea operations. Regarding the LNG liquefaction technology development,
Snøhvit will be the first application of own technology in Statoil’s business. Today, the Snøhvit LNG
Project is fully taking advantage of the long-term technology achievements of Statoil.
3
The Snøhvit environment strategy
Since the Snøhvit LNG chain is the first Norwegian hydrocarbon development in the Barents Sea,
there is a very high attention on the impacts regarding emissions to air and sea. The environment
strategy of the project is that CO2 produced from the reservoirs shall be returned to the reservoirs.
Further, that the gas and condensate chain shall be built according to internationally recognized Best
Available Technology (BAT) principles.
The most significant environmental contribution comes from installation of a re-injection system for
750 000 tons per year of CO2. This concept resembles the underground storage of CO2 already proven
feasible by the Statoil operated Sleipner Field in the North Sea. However, this is the first time such a
CO2 re-injection technology is applied in land based hydrocarbon industry.
The turbo-generators of the LNG plant discharge 900 000 tons per year of CO2 and 650 tons per year
of NOx. The environmental consequences of these emissions have a high focus in the Snøhvit LNG
Project.
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The life cycle cost robustness of the selected technology versus domestic taxation and future purchase
of quota according to the Kyoto Protocol is highly relevant in a Norwegian context. Additionally, the
overall thermal efficiency and emissions of the LNG plant is subject to formal approval by authorities
according to the national, stringent environmental agenda.
The result of the Snøhvit LNG Project’s environmental strategy is that energy needs in the offshore
transportation and onshore processing and liquefaction, up to products shipment, have an overall fuel
consumption of 6 % of the feed flow.
4
Selecting the LNG plant capacity
In 1999, the Snøhvit LNG Project involved engineering contractors, technology licensors and
machinery vendors in studies to identify optimal LNG train capacity. Specifically, the LNG process
should follow the state-of-the-art regarding train capacity. Studies documented the feasibility of
capacity up to approximately five million tons per annum (mtpa).
A screening of capacities and concepts was made to find technical solutions at different capacities.
First a coarse assessment was made to arrive at concepts based on high thermal efficiency and
maximum economy of scale. Then an evaluation was made in more detail based on life cycle cost
evaluations, taking into consideration given evaluation criteria such as processing equipment sizes and
potential duplication, availability and impact on the plot space (prefabricated process barge size
limitations). Further, including identification of main technology qualification work for the
recommended solution in order to reduce the risk with respect to increased capacity.
The impact of cold climate on reduced power demand in a liquefaction cycle in North Norway,
relative to most other LNG plant locations, plays a significant role in setting the train capacity. It
turned out that the key question, for the selection of technology and capacity, was the concept for
LNG liquefaction and not driver and cryogenic compressor selections, although these selections
themselves are very important and crucial for plant operability.
The screening, starting from 3.4 million tons LNG per year, referred to as 100 %, concluded that
attractive solutions were available in the range of 125 % - 150 % capacity. The relative investments
versus capacity reveal a significant economy of scale effect by capacity increases up to 5.1 mtpa. The
best potential of combining reduced unit cost with moderate technology and plant complexity is a train
capacity around 4.5 million tons of LNG per year.
Regarding the chain capacity, the project has balanced risks related to the reserves, the offshore and
onshore technology and market potential. Taking all relevant risks into consideration, the project
decided an LNG capacity of 4.3 mtpa in the single train plant. This is a nameplate capacity increase of
30 % from the previous engineering phase of the project in 1997. Additionally, the plant produces 0.2
mtpa LPG and 0.8 mtpa condensate. Comparisons of the Hammerfest LNG Plant with other plants,
shows that Snøhvit will be in the forefront on train capacity by the time of production in 2006.
5
Selecting power and heat system
To reach a robust driver configuration design, the project is applying life cycle cost evaluations, taking
the Norwegian offshore CO2 tax regime and BAT recommendations into the selection criteria. Driver
designs are checked versus fuel gas prices, reflecting upstream investments, and carbon dioxide taxes
in the range of 15 – 35 USD per ton. Under this regime, only the most energy efficient designs will be
competitive. Plant availability is a selection criterion, especially with regard to increased on-stream
days versus investments.
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Contractor I
Capacity
Contractor II
124%
136%
143%
125%
137%
150%
1.09
1.02
1
1.06
1
1.01
Technology Qualification *)
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Availability
Relative to 100 % capacity
Construction on barge
Compared to 100 % capacity
Complexity (X/Y/Z) **)
Equal
Equal
Equal
Equal
Lower
Equal
Complex
Complex
Equal
Equal /
Lower
Equal
Complex
4/2/1
5/2/2
4/2/2
2/1/2
1/2/1
4/2/2
3
2
1
2
1
3
Relative LCC/Unit cost
Ranking
*) Technology qualification definitions:
• None: Applications in relevant service identified
• Moderate: Modeling and calculations to be performed
• Extensive: Building and testing of prototype.
**) Complexity definition (X/Y/Z):
• X = Number of various types of drivers
• Y = Electrical 50 / 60 Hz; 50 Hz = 1, 50 & 60 Hz = 2
• Z = Heating system; Hot-oil = 1, Steam = 2
Table: Evaluation of concepts versus capacity
Statoil provided a list of pre-qualified drivers subject to the screening study. Specifically, the LM6000
was not pre-qualified for use in mechanical drive service on the basis of the present record of
operation. A pre-requisite is all gas turbines to be equipped with low NOx (DLE/DLN) combustors.
The screening comprised several different driver options including industrial heavy-duty gas turbines
and aero-derivative machines. Both direct mechanical drives for refrigerant compressors as well as
electrical motors were considered.
The second most competitive concept included a Frame 7 turbine driving two refrigerant compressors
and a steam turbine driving the third refrigerant compressor with steam as waste heat recovery system.
The power generation was alternatively based on one LM 6000 turbo-generator or supplementary
firing in the waste heat recovery unit supplying steam to a steam power generator.
The selected concept includes five LM 6000 turbo-generators providing power to an internal grid at a
site rated capacity of 46 MW each, supplying individual electrical variable speed motors (VSD) as
refrigerant compressor drivers. This concept disconnects the individual sizing constraints between
liquefaction compressors and gas turbines. The gas turbines are equipped with hot-oil waste heat
recovery system in the exhaust stacks. The availability of this electrified concept is approximately ten
on-stream days more per year than for an industrial heavy-duty based driver concept with steam as
waste heat recovery system.
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Operations strategy for the energy system
The power and heat system is designed as a utility, providing a reliable, fully self-sufficient supply to
the offshore transportation and the onshore processing of the Snøhvit area gas and condensate
production. The gas turbines provide all electric power to the refrigeration compressors and other
users, and all process heat required in the process plant.
The selected energy system provides a condition of stable operation to the LNG plant, improving the
revenues by increased on-stream days. The gas turbines have a backup from the domestic electricity
grid at a capacity of 50 MW. The access to power is therefore based on the strategy of “5 out of 6”
units in operation. With the power as the governing design factor, the waste heat recovery system,
equivalently, fulfills the strategy of “4 of out 5” units in operation. Which also means there is no
requirements for auxiliary gas fired units.
This configuration for the Hammerfest LNG Plant provides an electricity efficiency of 41 % and an
overall thermal efficiency of 71 %, using hot-oil for the waste heat recovery system.
Figure: The power and heat utility system
6
Evaluation and selection of the LNG process
In 1997 the Snøhvit project requested three contractors (Kellogg, Bechtel and Linde) to carry out
conceptual designs and execution strategies for a base load LNG plant located in Northern Norway.
Kellogg selected the APCI propane pre-cooled process, C3/MCR Liquefaction Process, in their
design. This is the far most utilized process for base load LNG plants, having been used in virtually
all base load LNG plants installed the last 25 years, with some few exceptions.
Bechtel applied the Optimized Cascade Liquefaction Process based on Phillips technology.
Linde based their design on a dual flow mixed refrigerant liquefaction process but recommended to
change the design to the newly developed proprietary Mixed Fluid Cascade Process.
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NG
E1A
CW1
E1B
C1
CW
2A/2B
E2
C2
CW
3A/3B
E3
C3
X1
LNG
Process description:
The process diagram is showing the Statoil -Linde LNG Technology Alliance's base-load process
consisting of three mixed refrigerant cycles, called the Mixed Fluid Cascade Process (MFCP).
The pre-cooling cycle mixture is compressed in compressor C1, liquefied in sea water cooler CW1 and
subcooled in cryogenic heat exchanger E1A. One part is throttled to an intermediate pressure and
used as refrigerant in E1A. The other part is further subcooled in heat exchanger E1B, throttled to the
suction pressure of compressor C1 and used as refrigerant in heat exchanger E1B.
The liquefaction cycle is compressed in compressor C2, cooled in sea water coolers CW2A and
CW2B, further cooled in heat exchangers E1A, E1B and E2. It is throttled and used as a refrigerant in
liquefier E2.
The sub-cooling cycle is compressed in compressor C3, cooled in sea water coolers CW3A and
CW3B, further cooled in heat exchangers E1A, E1B, E2 and E3, expanded in liquid turbine X1 and
used as refrigerant in subcooler E3.
All compressor suction fluids are slightly superheated above their dew points.
Figure: The Statoil – Linde proprietary MFC process
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After evaluations of the three conceptual designs, the project decided to go with Kellogg and Linde.
The Bechel proposed technology was rejected for further studies, since it turned out that its overall
energy efficiency was too low compared to the MFC process, the dual flow mixed refrigerant process
and the C3/MCR process, which virtually have the same efficiency.
Qualification of technology for increased capacity
The recommended process technologies included APCI's C3/MCR and Linde’s MFCP. The technical
reports from the both Linde and Kellogg were received in 1998. The technology offered by Kellogg
and Linde was qualified in accordance with Statoil’s quality control system. Qualification was based
on a yearly LNG production capacity of 3.4 mtpa.
However, as the LNG marked situation changed and opened for the possibility to take advantage of
the economy of scale, the overall yearly capacity was increased to 4.3 mtpa. This capacity increase
made it necessary to perform a new and more extensive technology qualification. At this time also the
APCI Dual Mixed Refrigerant (DMR) process was introduced for evaluation.
Selected LNG process technology
The technology selected for the Snøhvit LNG Project is the jointly owned LNG process design of
Statoil and Linde, developed during the LNG Technology Alliance in 1996-97. The patented process
is named - MFCP - the Mixed Fluid Cascade Process.
The Mixed Fluid Cascade process is a classic cascade process with the important difference that mixed
component refrigerant cycles replaces single component refrigerant cycles, and thereby improving the
thermodynamic efficiency and operational flexibility.
The following characteristics apply to the MFC process:
•
•
•
7
The MFC process is new, and as a whole without any industrial references. However,
the concept is build up by well-known elements
The size and complexity of the separate spiral wound heat exchangers (SWHE) applied
in the MFCP is considerably less when compared with today's single unit used in dual
flow LNG plants
The SWHE technology is extensively tested as an industrial scale prototype, since 1998,
for thermal, hydraulic and mechanical duties, in an LNG facility in South Africa.
Selected plant construction strategy
A considerable amount of the cost reduction potential lies in early focus on technology, construction
methods and procurement by utilising the global market. In the development of the execution strategy
for Snøhvit, focus has been placed on cost reductions related to all aspects of management,
engineering, procurement and construction.
The project involved the suppliers in front-end engineering in 1997-98. Several groups within process,
storage and civil engineering were challenged to provide their individual conceptual designs and
execution strategies for the Hammerfest LNG Plant. The contributions included novel fabrication
strategies for a land based LNG plant.
Site conditions play an important role in the planning of an industrial enterprise of this magnitude.
Weather conditions and infrastructure are significant factors in the project development. Maximum
prefabrication of the LNG plant is selected as the most cost effective construction strategy, due to
harsh winter conditions and infrastructure constraints on logistics in Northern Norway.
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The execution strategy comprises:
•
•
•
•
Maximum prefabrication by using the process barge concept
Minimizing construction manning on site in Hammerfest
Optimal and compact layout of the LNG plant
Meeting international safety codes.
Figure: The pre-fabricated process barge unit
The Snøhvit Process Barge
Among the most fundamental project decisions is to install the pre-treatment and liquefaction
processes and the power and heat systems of the Hammerfest LNG Plant in a compact layout on a
purpose built barge, thereby minimising construction work on site. The concept is making use of
European located yards and their skilled labour force in weather protected docking facilities.
Considering the specific site constraints, the project is achieving a quality and productivity
improvement by yard fabrication.
The concept comprises a fully equipped and pre-commissioned process barge. The process barge is
pre-fabricated and transported to site on the Norwegian coast of the Barents Sea. The prefabricated
Snøhvit Process Barge weighs totally approximately 35 000 tons in transportation.
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The marine activities are critical to the project. Marine transportation of the barge could be towing
from any European yard. However, using a special transportation solution based on a heavy lift vessel
reduced the transportation schedule and improves the overall safety of the transportation to
Hammerfest.
Arriving in Hammerfest, the process barge will be docked inside the LNG plant and ballasted down,
providing a permanent foundation for the process systems. After docking, the process barge will be
given a concrete deck and become an integral part of the overall LNG facility.
Compared to conventional LNG plant executions, the Snøhvit LNG Project has changed the
philosophy from on-site, stick-built solutions to yard prefabrication, placing focus on maximum work
executed in fabrication yards.
Prefabrication of the process on a purpose built barge due to the specific site constraints represents a
significant contribution to the overall cost reduction potential in construction and commissioning.
References sited
W Förg, W Bach, R Stockmann, Linde and R S Heiersted, P Paurola, A O Fredheim, Statoil: A New
LNG Baseload Process and Manufacturing of the Main Heat Exchangers. LNG 12 Conference, Perth,
May 1998.
R S Heiersted, S Jacobsen, S Nystrøm, Statoil: Project Execution Strategy for the Hammerfest LNG
Plant, Snøhvit LNG Project. Gastech 1998, Dubai, December 1998.
S W Jensen, E Herløe, S Jacobsen, R S Heiersted, Statoil: New Project Execution Strategy for Base
Load LNG Plants. Eurogas 99, Bockum, May 1999.
R S Heiersted, Statoil: Cost Reduction Potential of the Execution Strategy for the Snøhvit LNG Plant.
IBC’s International Forum on LNG, London, October 1999.
R S Heiersted, Statoil: Commercializing Snøhvit - An Atlantic Basin LNG Chain. CWC Group, World
LNG Summit, London, September 2000.
S W Jensen, Statoil: Developing the Snøhvit LNG Chain. Gastech 2000, Houston, November 2000.
R S Heiersted, R E Jensen, R H Pettersen, S Lillesund, Statoil: Capacity and Technology for the
Snøhvit LNG Plant. LNG 13 Conference, Seoul, May 2001.
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