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OLT Livorno FSRU: an innovative solution for the gas industry
Armando Favi – Saipem
The history of Saipem has been marked by numerous “firsts”. The Floating Storage and
Regas Unit (FSRU) constructed by Saipem on the basis of the EPCIC contract signed
with OLT, will be the first LNG regasification unit installed on a ship permanently
anchored in open sea, off the coast of Livorno. The FSRU is the solution with the
lowest environmental impact and is often considered as the only one capable of
obtaining the necessary construction permits.
The novelty of this plant meant that Saipem had to develop a totally original design, but
also led the client, OLT, to adopt an unusual contractual approach for Saipem and for
the offshore industry in general, based on an exclusive relationship right from the early
stages of the project.
With this project, Saipem inaugurated a new product range and gained a reference
which is being put to profitable use in other areas as well, such as offshore production
of liquefied natural gas or electricity.
The current structure of OLT has IREN and E.ON as controlling companies, with
46.79% each, OLT Energy Toscana with 3.73% and Golar LNG with 2.69%. The gas
importation capacity is expected to be used equally by IREN and E.ON.
1. The Livorno FSRU, an innovative solution
The FSRU is a LNG storage and regasification unit installed on a ship which is
permanently moored in the open sea, via a rotating turret. This is what makes it different
from other units installed in Brazil and elsewhere, which are moored in port or in
protected waters, and are therefore much simpler.
Our project is based on the use and conversion of an existing gas carrier – the Golar
Frost –purchased by OLT from the Norwegian ship owner Golar LNG.
The FSRU receives LNG from conventional gas carriers, which moor side by side to the
FSRU and unload the LNG through articulated loading arms similar to those used at the
coastal LNG terminals and installed on board the FSRU itself.
The LNG is stored in four Moss type spheres, with a total capacity of 135,000 m3, and
is then sent to the regasification unit, based on installation of three Tri-ex type
vaporizers with a capacity of 150 t/h each, manufactured by the Japanese firm Kobe
Steel.
The Tri-ex units are intermediate fluid (propane) heat exchangers and use sea water in
an open cycle as the heating medium for vaporization of the LNG.
The gas resulting from vaporization is sent to shore via an offshore pipeline connected
to the national network at Suese, in the Livorno hinterland.
OLT Livorno FSRU: an innovative solution for the gas industry
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2. The project and the role of Saipem
The initial idea of the project was conceived way back in 2002, when a group of
developers funded by Falck decided to satisfy the predictable requirement of the Italian
system for greater diversification in sources of gas supply and incorporated the
company Crossenergy (which later became OLT).
It should be noted that Italy still receives gas through offshore pipelines (Libya and
Algeria via Tunisia) and land pipelines (Russia, the Netherlands and Norway) and has
only two regasification terminals, the “ancient” Panigaglia plant operated by GNL Italia
of the Snam Rete Gas group, and the Rovigo terminal owned by Exxon, Qatargas and
Edison, formed of a gigantic and extremely expensive reinforced concrete island
(Gravity Base Structure).
The developers decided to contact Saipem to discuss possible technical solutions which
would overcome the multitude of problems created by authorization procedures and
which would ensure the project was bankable.
On Saipem’s suggestion, it was decided to start the adventure of the floating
regasification terminal, a completely new solution which, until then, had only been
studied on paper by several engineering companies, including Saipem’s subsidiary
Moss Maritime.
OLT felt the need to involve immediately a contractor capable of completing a project
which was so challenging in a variety of aspects. An exclusivity agreement was
therefore signed between OLT and Saipem, which involved the commitment for Saipem
to support OLT from the early phases and until construction of the plant, and the
commitment for OLT of conducting exclusively with Saipem direct negotiation of the
EPCIC contract.
From then, until the signing of the contract, Saipem constantly supported OLT,
providing added value which may be summarized into the following points:
•
development of a completely innovative conceptual solution, starting virtually with
a blank sheet of paper, and going as far as the technical definition necessary for
approval of feasibility of the unit and to produce a binding turn-key price
•
support to OLT in the activities involved for obtaining permits: preparation of the
documentation and discussion with the various authorities, and continuous
adjustments to the requirements communicated on an ongoing basis
•
support to OLT in promoting the project with potential future partners: gas off
takers (future clients of the unit) and LNG suppliers.
•
industrial qualification of all the innovative technical elements, such as side-by-side
mooring of the shuttle with the FSRU and use on the ship of loading arms and
vaporizers
•
completion of basic engineering and definition of the binding price.
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3. The unit
The FSRU is a LNG receiving terminal located in open sea 12 miles offshore Livorno
(Tuscany, Italy) in a water depth of about 120 meters.
The FSRU is built by converting the existing LNG carrier Golar Frost (Length O.A. =
288 m, Breadth MLD = 48 m, Deadweight = 80,000 ton).
The FSRU has 135,000 m3 LNG net storage capacity (4 spheres, 40 m diameter) and
three re-gasification units for a total output of 3.9 M tons/year, at a pressure of 55 to 80
bar. As a reference, this is the equivalent of the Bilbao onshore LNG receiving terminal.
The send out capacity of the regasification unit ranges from 100 to 450 ton/h of LNG.
When for any reason the gas send out is stopped, the plant can be kept in cold condition
(“zero send out” mode) through a continuous recirculation of LNG, in order to avoid a
new cool-down phase and thus reduce the start up time once the export is to be restored.
The conversion of the existing ship mainly includes the installation of external mooring
turret, re-gasification process modules and offloading arms.
Among the many technical challenges, three items were identified as innovative as
never used before in the offshore industry: the side by side mooring of two vessels, the
loading arms connecting two movable units and the static vaporizers subject to pitch
and roll on board the FSRU.
This will be the first floating re-gasification terminal ever built to work offshore in open
sea.
Operations in open sea depend strongly on sea conditions (Hs, current, wind, sea cross
conditions). The technical challenge for the project is to ensure satisfactory availability
of the unit in highly safe conditions for all anticipated sea states, in particular during the
side by side berthing and the subsequent unloading. This shall be possible within the
design meteomarine conditions for LNG carriers ranging from 60,000 to 135,000 m3
capacity. This operation is a prototype, proven by sophisticated computer analysis and
model testing.
The FSRU is supplied with LNG by carriers berthing side by side to the FSRU, through
4 loading arms at a flow rate of 12,000 m3 LNG/hour. This means that 12 hours are
required for unloading the largest LNG carrier of 135,000 m3 capacity, plus mooring
and de-mooring time. The terminal is designed to perform one unloading approximately
every 6 days. The loading lines are kept in cold condition between two unloadings
through a small recirculation of LNG, so as to shorten the cool-down phase and
therefore reduce the overall duration of the unloading operation.
This operation is held in open sea in non-standard, extreme conditions: the loading arms
are therefore considered a prototype. Special design and full-scale factory tests have
been carried out for their qualification.
The key components of the re-gasification process are the vaporizers. The FSRU is
equipped with three Tri-Ex type units using large quantities of seawater as a heating
medium.
OLT Livorno FSRU: an innovative solution for the gas industry
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Seawater is pre-heated by the heat generated in the main condenser of the steam power
generation system.
These vaporizers are the third prototype aspect of the project, being normally used
onshore in static conditions.
Many other works are required for the conversion. Practically most of the existing
systems are enhanced or modified to suit the needs of the FSRU: a new 20MW power
generation system, a modification of all the utilities systems, new telecommunications,
new radar, wave monitoring, fiscal metering, Wobbe index correction system to adapt
all type of LNG to the specification of the Italian distribution network.
Since the FSRU is an innovative product, midway between a ship and an LNG terminal,
the reference norms and regulations were not completely clear and consistent at the
beginning of the project, and Saipem worked closely with the Classification Society
(RINA) to define and obtain all the necessary certifications.
4. Project execution
The project is characterized by its highly technological and innovative content and has
been staffed by the different Saipem’s competence centres able to provide the required
expertise in these technological fields.
The project has been organized in task force with a project team based in San Giuliano
Milanese and a construction team based at the conversion yard in Dubai. The Client is
also located at both sites throughout the overall project duration.
The scope of work for Saipem encompasses all the phases of a typical major offshore
turn-key project: detail engineering, procurement, construction, installation and
commissioning, up to the performance test before handover to the Client.
The engineering could not be performed entirely in San Giuliano, and a substantial part
was executed in other engineering centres of the Group: naval engineering and
calculation of the fatigue of the hull were executed in Oslo by Moss, the design of the
subsea part (PLEM, risers, umbilicals) was done in Fano, the detailed engineering
activities of the hull conversion were performed in Brest by Sofresid Ouest, the turret
was designed by LMC in London.
The engineering teams based in San Giuliano are in charge of the topside modules
(regasification plant) and the main integrated systems (power distribution, control
system, telecommunications), as well as the interface management and supervision of
the various engineering centres.
The procurement activities are almost entirely executed in task force in San Giuliano
with some support from the Saipem SA procurement department (Paris).
The fabrication and construction activities were mostly performed in Dubai to fabricate
the topside modules (2,400 tons) at the Lamprell fab yard and to convert the hull of the
Golar Frost and integrate the modules at the Drydocks World Dubai shipyard. During
OLT Livorno FSRU: an innovative solution for the gas industry
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the works on site, Saipem scope included the refurbishment of all the critical
unmodified existing equipment and systems (“Zero hours service”).
In relation with the highly innovative content of the project, the commissioning
activities have been initiated at the award and the commissioning teams are strongly
involved in all phases of the project: engineering, procurement, construction. Before the
sail away from Dubai, the FSRU will be subject to a first intensive commissioning
campaign (onshore commissioning).
After leaving Dubai the FSRU will be towed through the Suez Canal up to its final
position offshore Livorno to be reached by early 2013. The installation scope includes
the installation of chains and anchors, the mooring of the FSRU, the installation of the
risers, umbilical and subsea station. The offshore installation and hook-up work will last
70 days.
Then the offshore commissioning will take place, also including one month of reliability
runs and one month of performance tests before the provisional acceptance targeted
within second quarter of 2013.
Artistic view of the OLT Livorno FSRU
OLT Livorno FSRU: an innovative solution for the gas industry
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26thJune 2012-5
Artistic view of the side by side offloading operation
The main conversion scope
OLT Livorno FSRU: an innovative solution for the gas industry
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Conversion works at the Drydocks World Dubai shipyard
OLT Livorno FSRU: an innovative solution for the gas industry
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26thJune 2012-7