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Title:
HYDROCARBON PROCESSING PLANT WITH A WATER INTAKE SYSTEM
Document Type and Number:
WIPO Patent Application WO/2016/038087
Kind Code:
A1
Abstract:
The invention relates to a hydrocarbon processing plant (1) comprising a hull (10) which, in use, is at least partially submerged in a body of water. The hull (10) comprises a storage tank (20) suitable for storing liquefied natural gas. The hydrocarbon processing plant (1) comprises a water ballast tank (30) positioned between the hull (10) and the storage tank (20). The hydrocarbon processing plant (1) comprises a heat exchanger (40) and a water intake system (50). The heat exchanger (40) is in fluid communication with the water intake system (50) via a piping system (60) to supply water to the heat exchanger (40). At least part of the piping system (60) is routed through the water ballast tank (30).

Inventors:
VAN DER WAL ROBBERT (NL)
DAVEY SCOTT M (GB)
NA CHRISTIAAN M (NL)
FRANCIS AUGUSTINE (NL)
BRANDT ROEL (NL)
VAN DOORNE CASIMIR WILLEM HENDRIK (NL)
Application Number:
PCT/EP2015/070606
Publication Date:
March 17, 2016
Filing Date:
September 09, 2015
Export Citation:
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Assignee:
SHELL INT RESEARCH (NL)
SHELL OIL CO (US)
International Classes:
B63B25/16; B63B35/44; F25J1/02
Domestic Patent References:
WO2011118228A12011-09-29
WO2011101461A12011-08-25
WO2012066039A12012-05-24
Foreign References:
JP2010058772A2010-03-18
KR20110130135A2011-12-05
KR20110061876A2011-06-10
US4041721A1977-08-16
Attorney, Agent or Firm:
MATTHEZING, Robert, Maarten (PO Box 384, 2501 CJ The Hague, NL)
Download PDF:
Claims:
C L A I M S

1. Hydrocarbon processing plant (1) comprising a hull (10) which, in use, is at least partially submerged in a body of water, the hull (10) comprises a storage tank (20) suitable for storing liquefied natural gas,

wherein the hydrocarbon processing plant (1) comprises a water ballast tank (30) positioned between the hull (10) and the storage tank (20),

wherein the hydrocarbon processing plant (1) comprises a heat exchanger (40) and a water intake system (50), the heat exchanger (40) being in fluid communication with the water intake system (50) via a piping system (60) to supply water to the heat exchanger (40), wherein at least part of the piping system (60) is routed through the water ballast tank (30) .

2. Hydrocarbon processing plant (1) according to claim 1, wherein at least part of the piping system (60) routed through the water ballast tank (30) is positioned underneath the storage tank (20) .

3. Hydrocarbon processing plant (1) according to any one of the preceding claims, wherein the water intake system (50) is a side water intake system.

4. Hydrocarbon processing plant (1) according to any one of the preceding claims, wherein the water intake system (50) comprises a plurality of water intake openings (51) in the hull (10) .

5. Hydrocarbon processing plant (1) according to claim 4, wherein each water intake opening (51) has an associated water intake conduit (61) and an associated water intake pump (62) .

6. Hydrocarbon processing plant (1) according to any one of the preceding claims, comprising a plurality of water intake pumps (62), wherein the water intake pumps (62) are

positioned in a shared pump room (63) .

7. Hydrocarbon processing plant (1) according to claim 6, wherein the pump room (63) is located horizontally adjacent to the storage tank (20) .

8. Hydrocarbon processing plant (1) according to any one of the claims 1 - 5, wherein the hydrocarbon processing plant (1) comprises a water intake pump (62), wherein the water intake pump (62) is positioned in the water ballast tank (30) .

9. Hydrocarbon processing plant (1) according to any one of the preceding claims, wherein the water intake system (50) comprises an air disengagement tank (70) positioned in the water ballast tank (30) .

10. Hydrocarbon processing plant (1) according to any one of the preceding claims, wherein the water intake system (50) comprises an inlet filter (52) and a blast device (80) to blast gas or air through the inlet filter (52) in a direction opposite to a water intake direction. 11. Hydrocarbon processing plant (1) according to any one of the preceding claims, wherein the water intake system (50) comprises an anti-fouling supply system (90) to supply an anti-fouling agent to the piping system (60) .

12. Hydrocarbon processing plant (1) according to any one of the preceding claims, wherein the hydrocarbon processing plant (1) is arranged to process natural gas by liquefying a vaporous hydrocarbon containing feed stream and storing the liquefied natural gas in the at least one storage tank (20) and/or by gasifying a liquefied hydrocarbon containing stream taken from the at least one storage tank (20) . 13. Method of operating a hydrocarbon processing plant (1) according to any one of the preceding claims .

14. Method according to claim 13, wherein the method

comprises comprising:

- providing a vaporous hydrocarbon containing feed stream and supplying it to the heat exchanger (40),

- taking in water using the water intake system (50) and supplying it to the heat exchanger (40);

- forming a liquefied hydrocarbon stream by extracting heat from the vaporous hydrocarbon containing feed stream using the heat exchanger (40);

- storing at least part of the obtained liquefied hydrocarbon in the storage tank (20) . 15. Method according to any one of the claims 13 - 14, wherein the method comprises :

- obtaining a liquefied hydrocarbon containing feed stream from the storage tank (20),

- taking in water using the water intake system (50) and supplying it to the heat exchanger (40);

- forming a vaporous hydrocarbon stream by adding heat to the liquefied hydrocarbon containing feed stream using a heat exchanger (40) .

Description:
Hydrocarbon processing plant

with a water intake system

TECHNICAL FIELD

The present invention relates to a hydrocarbon processing plant and a method of operating of such a hydrocarbon processing plant.

STATE OF THE ART

A commercially important liquefied hydrocarbon is liquefied natural gas (LNG) , which is typically produced by extracting heat from a natural gas stream whereby the natural gas is cooled to reach a temperature that is below the bubble point of the LNG at atmospheric pressure. The temperature is typically about -162 °C. The removed heat is generally brought into the ambient. In case of a water-cooled LNG production process, the heat is removed by cooling (sea) water and generally released into the ambient, e.g. sea.

Before use by an end user, the LNG is typically

revaporized, which involves withdrawing heat from the ambient and adding this heat to the LNG. The heat may be taken from a stream of (sea) water.

The term hydrocarbon processing plant is used in this text to refer to plants processing natural gas by liquefying a vaporous hydrocarbon containing feed stream and/or by gasifying a liquefied hydrocarbon containing stream.

Floating hydrocarbon processing plants are known which are provided on floating structures. An example of a floating hydrocarbon processing plant is a floating liquid natural gas vessel (FLNG vessel) . Such floating hydrocarbon processing plants comprise a hull and comprise at least one LNG storage tank for storing liquefied natural gas. Also known are hydrocarbon processing plants with are provided on gravity based off-shore structures. These will be referred to in this text as off-shore gravity based

hydrocarbon processing plants. These structures comprise a hull which is positioned on the bottom of a body of water.

The hull of these structures can be made of concrete or steel and comprise permanent ballast tanks. The ballast tanks are empty during transportation of the structure and are filled with water to sink the structure on the intended location.

WO2011101461 relates to a floating hydrocarbon processing vessel comprising a plurality of first storage tanks arranged on a starboard side of a longitudinal mid-plane of the vessel, a plurality of second storage tanks arranged on the port side of the longitudinal mid-plane and in symmetrical side-by-side arrangement with the plurality of first storage tanks. The vessel further comprises at least one longitudinal bulkhead extending along the mid-plane and located between adjacent first and second storage tanks.

Floating hydrocarbon processing vessels are further known to comprise at least one water ballast tank for storing ballast water to keep the floating LNG plant at a desired draught even when the floating LNG plant is not or only lightly loaded. The water ballast tanks are in fluid

communication with a ballast water intake and outlet system. The water ballast tanks may be located in between the hull of the vessel and the LNG storage tanks, in particular extending in the space underneath the LNG storage tanks .

Hydrocarbon processing plants comprise equipment, including heat exchangers, to cool a vaporous hydrocarbon containing feed stream to produce a liquefied hydrocarbon containing stream and/or heat a liquefied hydrocarbon containing stream to produce a vaporous hydrocarbon

containing feed stream. Both in liquefying and vaporizing hydrocarbon processing plants water is taken in. Therefore, a water intake system is provided to take in water from the body of water the

hydrocarbon processing plant is located in, which water is fed to the heat exchangers as cooling/heating medium.

The water intake system for taking in cooling or heating water is separated from a ballast water intake and discharge system.

Floating hydrocarbon processing plants often comprise a water intake riser assembly being suspended from the floating structure into the body of water to take in water from a certain depth and supply the water to the heat exchangers via the water intake riser assembly. The water is used to add heat to, or remove heat from, a hydrocarbon stream.

Subsequently the water is disposed of. An example of such a floating hydrocarbon processing plant is provided in

WO2012066039.

In some cases, it is not possible to use water intake riser assemblies. This is for instance the case when the floating hydrocarbon processing plant is operational in shallow waters or in case of a gravity based off-shore hydrocarbon processing plant.

US4041721 provides an example of a floating natural gas processing plant using side water intake systems. The side water intake system is provided in a side wall of the hull of the vessel. Water intake pumps are provided to take water in.

On floating and gravity based off-shore hydrocarbon processing plants the available space is usually limited, so it is a challenge to design the plants such that a certain intended production capacity is reached with a minimum sized structure, or, a maximum production capacity is obtained with a certain sized structure. When designing the plants, many factors are to be taken into account, including economical, safety and maintenance considerations. The pipes, such as water intake pipes, should be accessible by staff for inspection and maintenance, but also economical (not too long) and should not compromise the safety of the facility.

SHORT DESCRIPTION

It is an object to provide a hydrocarbon processing plant which is designed in a more space-efficient way.

The term 'comprising' is used in this text to indicate that all the enlisted elements are encompassed without excluding the presence of additional non-named elements.

In accordance with an aspect of the present invention, there is provided a hydrocarbon processing plant 1 comprising a hull 10 which, in use, is at least partially submerged in a body of water, the hull 10 comprises a storage tank 20 suitable for storing liquefied natural gas, wherein the hydrocarbon processing plant 1 comprises a water ballast tank 30 positioned between the hull 10 and the storage tank 20, wherein the hydrocarbon processing plant 1 comprises a heat exchanger 40 and a water intake system 50, the heat exchanger 40 being in fluid communication with the water intake system 50 via a piping system 60 to supply water to the heat exchanger 40, wherein at least part of the piping system 60 is routed through the water ballast tank 30.

Such a design avoids routing of the pipelines outside the hull where the risk of pipelines being damaged by other floating vessels/ob ects is minimized. When routed through the process deck in the topside will increase the topside congestion in turn will increase the maximum over pressure risk. This design makes very efficient use of the space available on the hydrocarbon processing plant 1.

Furthermore, the part of the piping system routed through the water ballast tank is easily accessible by personnel for inspection and maintenance. More than one storage tank 20 may be present. More than one water ballast tank 30 may be present .

The hydrocarbon processing plant may be a floating hydrocarbon processing plant or a gravity based off-shore hydrocarbon processing plant.

The hydrocarbon processing plant 1 comprises a

(elongated) hull 10, comprising side walls 11, a base 12 extending between the side walls 11, a deck 13 being located atop the hull 10 and between the side walls 11. The

hydrocarbon processing plant 1 may comprise at least one processing deck 14, which is elevated with respect to the deck 13.

For a floating hydrocarbon processing plant, the hull, in particular the side walls and the base are typically made of steel. For a gravity based off-shore hydrocarbon processing plant, the hull, in particular the side walls and the base are typically made of concrete or steel.

One or more heat exchangers 40 are typically positioned on the processing deck 14 or below the deck 13 in the substructure and are arranged to allow heat to be exchanged between a hydrocarbon stream, e.g. natural gas (in liquefied and/or vaporized form) and water. Hydrocarbon processing plants for vaporizing liquid natural gas typically deploy the heat exchangers on the processing deck. Hydrocarbon

processing plants for liquefying natural gas typically deploy the heat exchangers inside the hull, i.e. in the hull machinery space, possibly with one or more additional heat exchangers on the (processing) deck. The skilled person will understand that the heat exchanger 40 is part of a line up for liquefying or vaporizing the hydrocarbon stream. A more detailed discussion of the cooling or heating line up is not deemed necessary. A storage tank is suitable for storing liquefied natural gas if the tank is capable of withstanding the cryogenic conditions associated with liquid natural gas (temperatures of -162°C and less), including during filling and emptying the storage tank. Storage tanks for liquefied natural gas typically fall into one of the following categories : SPB, Kvaerner-Moss , and membrane tanks.

The SPB tank (Self-supporting Prismatic Type "B") is a free-standing tank system. The SPB design has flat walls which are internally stiffened by webs and girders to reduce the stresses and deflections to acceptable limits under service conditions .

The Kvaerner-Moss tank is a spherical tank system. The sphere contains no internal structural members or bulkheads, and usually can withstand sloshing of the cryogenic contents thereof .

Membrane tanks are tanks wherein the inner surface is provided with a membrane. The membrane may be Invar or stainless steel.

According to an embodiment at least part of the piping system 60 routed through the water ballast tank 30 is positioned underneath the storage tank 20.

The water ballast tank 30 may comprise a base part 31 extending in a space between one or more storage tanks 20 and a base of the hull 10. The base part 31 is thus positioned underneath the storage tank 20. At least part of the piping system is routed through the base part 31 of this water ballast tank 30.

The water ballast tank 30 may further comprise one or more parts 32 being positioned beside the one or more storage tanks 20, i.e. in between the storage tanks 20 and the side wall 11 of the hull. The water ballast tank 30 may be segmented, i.e. divided in two or more components. According to an embodiment the water intake system 50 is a side water intake system.

Such a side water intake system comprises at least one water intake opening 51 in a wall, in particular a side wall of the hull 10. The water intake openings are located in a part of the (side) wall that is, in use, located underwater.

The term wall is used to refer to a vertical part of the hull 10. The hull 10 may typically be an elongated hull 10, in which case the side wall of the hull 10 extends in an elongated direction of the hull 10.

As the capacity of such a water intake opening 51 is limited, more than one water intake opening 51 may be needed.

According to an embodiment the water intake system 50 comprises a plurality of water intake openings 51 in the hull 10.

For instance, the water intake system may comprise four, five, six, seven, eight, nine or ten water intake openings 51. This makes the necessary piping system 60 for

transporting the water to the heat exchangers 40 more voluminous and makes the space efficient design even more advantageous . The plurality of water intake openings may be positioned in the side wall of the hull.

The water intake openings 51 may be provided in a straight or staggered horizontal row along the hull 10 of the structure. The term staggered is used to indicate that the water intake openings are positioned on different horizontal positions, but are not positioned on the same height, for instance in a " „°„°„° "-configuration. The water intake openings may also be provided in two straight horizontal rows, the water intake openings of one row being above the water intake openings of the other row. According to an embodiment each water intake opening 51 has an associated water intake conduit 61 and an associated water intake pump 62.

So, the piping system may comprise a plurality of water intake conduits 61, each water intake conduit 61 being associated with one water intake opening 51 to transport water from the respective water intake opening 51 through an associated water intake pump 62 to the heat exchanger (s) 40.

This is advantageous as it allows controlling the water intake via each water intake opening 51 individually and allows for adjusting the pump settings per water intake opening 51. Furthermore, the water intake can be interrupted for one or more individual water intake openings 51, for instance in case maintenance is needed.

Alternatively, the water intake conduits 61 may be interconnected, the interconnections comprising controllable valves. According to a further alternative, a group of two or more water intake openings shares a water intake pump. In such an embodiment, the water intake conduits of the group are connected to a shared water intake conduit, which is connected to an associated water intake pump. These

arrangements provide the system with more availability and reliability .

It will be clear however that providing a plurality of water intake openings 51, water intake conduits 61 and water intake pumps 62 makes the water intake system more voluminous and thus makes the efficient suggested routing of the piping system even more advantageous.

According to an embodiment the hydrocarbon processing plant comprises a plurality of water intake pumps 62, wherein the water intake pumps 62 are positioned in a shared pump room 63. Preferably, each water intake opening 51 has one

associated water intake pump 62, which allows for individual control of the water intake via the respective water intake openings 51, making the water intake less prone to pump failures and blockages. Alternatively, water intake pumps may be associated with more than one water intake opening, for instance via the above mentioned interconnections comprising controllable valves.

Alternatively, each water intake pump 62 is associated with a group of water intake openings 51.

The water intake pump(s) 62 is/are in fluid communication with the associated water intake opening 51 via at least part of the associated water intake conduit 61 to pump in water through the associated water intake opening 51.

Preferably, the one or more water intake pumps 62 are not positioned in the water ballast tank 30, but in a pump room which is fluidly separated from the water ballast tank 30. By putting all the water intake pumps 62 in a shared pump room 63, the available space is used in an efficient manner, as for instance power supply and control lines for the water intake pumps can be combined. The location of the pump room is selected taking into account length of the piping system and space utilization.

According to an embodiment the pump room 63 is located horizontally adjacent to the storage tank 20. The location of the pump room is preferably chosen close to the water intake openings to minimize the length of the piping system 60. This reduces the maintenance costs, reduces the available space needed for the piping system and also reduces the maintenance costs of the piping system.

The pump room 63 is preferably positioned between the aft machinery space and the storage tanks 20, wherein the pump room may be positioned beneath fluid storage tanks 64 e.g. slop tanks, chemical tanks, condensate tanks and water storage tanks. Alternatively the pump room 63 can also be located inside the machinery room.

According to an embodiment the hydrocarbon processing plant comprises a water intake pump 62, wherein the water intake pump 62 is positioned in the water ballast tank 30.

The water intake pump may be in fluid connection with one or more water intake openings . In case more than one water intake openings are provided, more than one water intake pump may be provided. Preferably, the number of water intake openings and water intake pumps are equal, which each water intake opening having a single associated water intake pump.

According to an embodiment the water intake system 50 comprises an air disengagement tank 70 positioned in the water ballast tank 30.

In order to allow entrained air to escape from the water taken in, an air disengagement tank 70 with a vent channel 80 may be provided. Preferably, each water intake opening 51 has its own associated air disengagement tank 70.

The air disengagement tank 70 may comprise a tank inlet which is formed by or is in fluid communication with a water intake opening of the (side) water intake system 50. The air disengagement tank 70 comprises a tank outlet 71 which is in fluid communication with the piping system 60. A flow obstruction element 72, e.g. a weir, may be provided in between the tank inlet and the tank outlet. The flow

obstruction element 72 obstructs the flow of water from the tank inlet 51 to the tank outlet 71 and thus lengthens the residence time of the water in the air disengagement tank 70. This ensures that the entrained air is properly disengaged and not carried forward to the water intake pump . The vent channel 80 comprises a vent channel inlet 81 being in fluid communication with an opening in the upper half of the air disengagement tank 70 and a vent channel outlet 82 being in fluid communication with the vent channel inlet 81, the vent channel outlet 82 being at a higher level than the vent channel inlet 81.

Providing such an air disengagement tank 70 with a vent channel 80 allows air to escape from the water before the water reaches the water intake pumps 62 and thereby reduces air associated damage to the water intake pumps 62 and subsequent equipment, e.g. caused by cavitation.

The air disengagement tank 70 may be positioned in the water ballast tank 30. At least part of the vent channel 80 may be routed through the water ballast tank 30, in

particular in the part of the water ballast tank 32 located in between the storage tanks 20 and the side wall 11 of the hull.

The one or more water intake pumps may be positioned close to the water intake openings . In case an air

disengagement tank is provided (discussed in more detail below) , the water intake pumps may be positioned inside or adjacent the respective air disengagement tanks. In case the water intake pump is positioned inside the air disengagement tank it is preferably positioned downstream of the flow obstruction element, if present.

According to an embodiment the water intake system 50 comprises an inlet filter 52 and a blast device 80 to blast gas or air through the inlet filter 52 in a direction opposite to a water intake direction.

In particular when side water intake systems are used instead of water intake risers, the risk of contamination or blockage of the water intake system is relatively high, e.g. caused by marine growth, marine life, silts, and pollution.

Inlet filter systems, comprising an inlet filter, allow water to flow through or towards the water intake opening, while preventing particles and marine life with a certain minimum size to flow through the inlet filter system. The inlet filter system may be positioned in the water intake opening. The inlet filter system may also be provided in a housing which is attached to the hull and is positioned on the outside of the hull in fluid communication with the water intake opening. The housing comprises one or more openings which are in fluid communication with the body of water. The housing may not comprise pumps and is referred to as a passive inlet filter system. Commercially available inlet filter systems may be used, such as Johnson Screens®, passive water intake screens from Euroslot Kdds . , Ovivo or Screen Services .

Operating the blast device 80 creates a counter flow which removes contamination from the inlet filter system, in particular from the inlet filter 52. The blast device 80 comprises an air or gas supply unit 81, e.g. a high pressure air storage which is fed by a supply either from a common header or a separate pressure device e.g. compressor to increase the pressure and a blast conduit 82 which is with one end connected to the supply unit 81 and has another end directed to the inlet filter 51 in a direction opposite to the water intake direction. The blast conduit 82 comprises a controllable valve 83 to open or close the blast conduit. Opening the valve 83 initiates a blast, closing the valve 83 terminates the blast. The one or more controllable valve may be positioned on the (processing) deck or inside the water ballast tank 30. At least part of the blast conduit is routed through the water ballast tank 30.

In case more than one water intake opening is provided, more than one blast devices may be provided, although they may share certain parts, such as the (high pressure) air storage. The one or more (high pressure) air storages may be positioned on the (processing) deck.

According to an embodiment the water intake system 50 comprises an anti-fouling supply system 90 to supply an anti- fouling agent to the piping system 60.

The anti-fouling agent may be injected inside or directly downstream of the water intake opening 51 or inside or directly downstream of the inlet filter 52.

The anti-fouling agent prevents marine growth development inside the water intake system 50. An example of an anti- fouling agent is hypochlorite, typically sodium hypochlorite.

The anti-fouling supply system 90 comprises an anti- fouling agent supply unit 91 (e.g. comprising an anti fouling agent pump and/or an anti-fouling storage) and an anti- fouling supply conduit 92 which is with one end connected to the anti-fouling agent supply unit and has another end located in the vicinity of the water intake opening or filter system, for instance in air disengagement tank 70. At least part of the anti-fouling agent supply conduit 92 is routed through the water ballast tank 30, in particular through the part of the water ballast tank 32 located in between the storage tanks 20 and the side wall 11 of the hull. A pump 93 is provided to pump the anti fouling agent to the piping system 60 or to the air disengagement tank 70.

The anti-fouling agent supply system is preferably positioned on the (processing) deck with the anti-fouling supply conduit at least partially running through the water ballast tank. The anti-fouling supply conduit may run through the water ballast tank and may run through the water intake opening 51 towards the filter system.

According to an embodiment the hydrocarbon processing plant 1 is arranged to process natural gas by liquefying a vaporous hydrocarbon containing feed stream and storing the liquefied natural gas in the at least one storage tank 20 and/or by gasifying a liquefied hydrocarbon containing stream taken from the at least one storage tank 20.

Liquefying and gasifying involve the use of one or more heat exchangers.

In case the hydrocarbon processing plant is a floating hydrocarbon processing plant moored in weathervaning manner on a mooring point, such as a turret or soft yoke, the water intake system 50 and the water intake openings 51 are preferably positioned in the longitudinal half of the hull furthest removed from the mooring point, e.g. the turret. This minimizes the length of the piping system. Alternatively the position can also be in the bow or aft to minimize the recirculation effect and to minimize the piping length.

Water discharge openings for discharging water that has been used in the one or more heat exchangers are preferably also positioned in the longitudinal half of the hull furthest from the mooring point, e.g. the turret, but on a side opposite of the side where the water intake openings are provided, to prevent the risk or recirculation.

According to a further aspect there is provided a method of operating a hydrocarbon processing plant 1 according to the above.

According to an embodiment the method comprises:

- providing a vaporous hydrocarbon containing feed stream and supplying it to the heat exchanger 40,

- taking in water using the water intake system 50 and supplying it to the heat exchanger 40;

- forming a liquefied hydrocarbon stream by extracting heat from the vaporous hydrocarbon containing feed stream using the heat exchanger 40;

- storing at least part of the obtained liquefied hydrocarbon in the storage tank 20. According to an embodiment the method comprises:

- obtaining a liquefied hydrocarbon containing feed stream from the storage tank 20,

- taking in water using the water intake system 50 and supplying it to the heat exchanger 40;

- forming a vaporous hydrocarbon stream by adding heat to the liquefied hydrocarbon containing feed stream using a heat exchanger 40.

SHORT DESCRIPTION OF THE DRAWINGS

The invention will be further illustrated hereinafter by way of example only, and with reference to the non-limiting drawing in which:

Fig. 1 schematically shows a cross sectional view of a floating hydrocarbon processing plant according to an embodiment

Fig.'s 2a - 2b schematically show a cross sectional top and side view respectively of a floating hydrocarbon

processing plant according to an embodiment,

Fig.'s 3a - 3b schematically show a cross sectional top and side view respectively of a floating hydrocarbon

processing plant according to an different embodiment,

Fig. 4 schematically shows a cross sectional side view of a floating hydrocarbon processing plant according to a further embodiment .

DETAILED DESCRIPTION

In this description same reference numbers refer to similar components. The person skilled in the art will readily understand that, while the invention is illustrated making reference to one or more a specific combinations of features and measures, many of those features and measures are functionally independent from other features and measures such that they can be equally or similarly applied

independently in other embodiments or combinations.

Below description relates a floating hydrocarbon

processing plant as shown in the Figures. However, it will be understood that below description also applies for gravity based off-shore hydrocarbon processing plants.

Fig. 1 schematically depicts a side view of a floating hydrocarbon processing plant 1. The hull 10 comprises side walls 11, a base 12 and a deck 13. On top of the deck 13 an elevated processing deck 14 may be present. Inside the hull is storage tank 20 for storing liquefied natural gas. The storage tank is surrounded by a water ballast tank 30 comprising a base part 31 and a side parts 32 being in between the storage tanks and the side walls 11 of the hull 10.

On the processing deck a heat exchanger 40 is shown. It will be understood that additional equipment will be present, such as compressors, valves, vessels, pumps, air coolers etc. However, for reasons of clarity, only a single heat exchanger 40 is shown. This heat exchanger 40 may be any type of suitable heat exchanger, such as a plate type heat exchanger.

The heat exchanger may be arranged to receive water, discharge water, receive a refrigerant and discharge

refrigerant, where inside the heat exchanger the water and the refrigerant are able to exchange heat.

Further shown is a water intake opening 51 provided in a side wall 11 of the hull 10. The water intake system 50 shown is may thus be referred to as a side water intake system.

The water intake opening 51 is used to take in water which is to be used in one or more heat exchangers for cooling or heating purposes. A piping system 60 is provided which connects the water intake opening 51 with the heat exchanger 40. The piping system is not shown completely in Fig. 1 but it will be understood that the piping system may comprise all sorts of equipment to convey the water from the water intake opening 51 to the heat exchanger 40, such as pumps, conduits, filters, storage vessels etc.

As shown in Fig. 1, at least part of the piping system 60 is routed through the water ballast tank 30, in particular through a base part 31 of the water ballast tank 30.

Outside of the hull 10 an inlet filter system 52

comprising an inlet filter may be provided to filter the water and thereby prevent marine life and debris from entering the piping system 60.

One or more water intake pumps may be provided on any suitable location.

Fig. 2a and 2b schematically depict a further embodiment in which the water intake system 50 comprises a plurality of water intake openings 51 with a plurality of inlet filter systems comprising an inlet filter 52. The piping system 60 comprises a plurality of water intake conduits 61 each extending at least partially through the water ballast tank 30. Each water intake conduit 61 comprises an associated water intake pump 62. All water intake pumps 62 are

positioned in a pump room 63. Downstream of the water intake pumps 62, the water intake conduits 61 are joined to form a combined water intake conduit 65 which discharges the water to the one or more heat exchangers. Fig. 1 shows a single combined water intake conduit 65. According to an

alternative, two or more combined water intake conduits 65 may be provided, each combining one or more water intake conduits 61.

As shown in the drawings, at least part of the water intake conduits 61 runs underneath a storage tank 20 suitable for storing liquefied natural gas . The pump room 63 is located horizontally adjacent one of the storage tanks 20 and may be positioned below fluid storage tanks 64 e.g. slop tanks, chemical tanks, condensate tanks and water storage tanks. Alternatively the pump room 63 can also be located inside the machinery room (not shown) .

Fig.'s 3a and 3b schematically depict an alternative embodiment, wherein the water intake pumps 62 are positioned inside the water ballast tank 30, in particular in the base part 32 thereof. The water intake pumps 62 are positioned adjacent or at least close to the water inlet openings 51.

Fig.'s 3a - 3b further schematically depict the presence of air disengagement tanks 70. Each water intake opening 51 may have one associated air disengagement tank 70. The air disengagement tank 70 comprises a flow obstructions element 72 and has a vent channel 80 which allows air to escape from the water. The water intake pumps 62 are positioned inside the water ballast tank 30.

Fig. 4 shows a further embodiment comprising an air disengagement tank 70 positioned in the water ballast tank 30 with the water intake pump 62 being positioned inside the air disengagement tank 70. The water intake pump 62 is positioned downstream of the flow obstructions element 72, inside or at least partially inside the air disengagement tank 70.

Further shown in Fig. 4 is a blast device 80, comprising an air or gas supply unit 81, a blast conduit 82 and a controllable valve 83 as described above. The supply unit 81 is positioned on the deck 13 by way of example. The blast conduit 82 is at least partially routed through the water ballast tank 30, in particular through the part of the water ballast tank 32 located in between the storage tanks 20 and the side wall 11 of the hull.

Fig. 4 further shows an anti-fouling supply system 90 to supply an anti-fouling agent to the piping system 60, for instance by introducing the ant-fouling agent into the air disengagement system 70.

The anti-fouling supply system 90 comprises an anti- fouling agent supply unit 91, an anti-fouling supply conduit 92 and a pump 93 provided to pump the anti fouling agent from the supply unit 91 to the piping system 60. The anti-fouling supply unit 91 may comprise a discharge nozzle 94 at the end remote of the supply unit 91.

The person skilled in the art will understand that the present invention can be carried out in many various ways without departing from the scope of the appended claims.