Selective positioning of a pump tower in a storage tank for liquified natural gas

Abstract

A floating gas plant can include a deck that may be reinforced. A topside unit can be positioned on the deck. The topside units may be one or more of: a processing unit, or a liquefaction unit, or a regasification unit, or a compression unit, or an injection unit, or a utility unit, or any combination thereof. The plant can also include a storage tank for storing the liquified gas, where the storage tank is positioned below the deck. A pump tower can be disposed in the storage tank, such that a portion of the pump tower protrudes through a surface level of the deck. The pump tower can be coupled to the deck for stability. Coupling the pump tower to the deck for stability can allow the pump tower to be positioned in any suitable location in the storage tank.

Description

SELECTIVE POSITIONING OF A PUMP TOWER IN A STORAGE TANK FOR LIQUIFIED NATURAL GASTechnical Field

[0001] The present disclosure relates generally to a storage tank for liquified natural gas. More specifically, but not by way of limitation, this disclosure relates to a pump tower that can be selectively positioned at a desired location in the storage tank for liquified natural gas.Background

[0002] A storage tank for liquified natural gas (LNG) is typically a large, heavily insulated container designed to safely store LNG at very low temperatures, such as -162°F (-260°C). Such storage tanks may include a series of layers for safety and maintaining the low temperature.

[0003] LNG storage tanks normally have a pump tower positioned therein for pumping LNG into and out of the tank. The pump tower can have a structural frame to support its other components. The pump tower can also include a pump (e.g., a centrifugal pump), a motor that provides the necessary power to operate the pump, a baseplate for support and stability, a cooling system to prevent overhearing of the pump and motor components, various valves and sensors for safety and monitoring, etc. The pump tower can span the height of the storage tank and may protrude through the top of the storage tank at a liquid dome or other opening, where connections to external piping outside of the storage tank can be made.

[0004] LNG storage tanks are often positioned on carrier ships to transport LNG by sea to a destination port. A single carrier ship may include one or more LNG storage tanks. These carrier ships normally lack any liquefaction and other LNG plant functionality and are merely used as transport vessels. In contrast to carrier ships, floating liquified natural gas (FLNG) plants are floating units (e.g., ships or platforms) that can produce, store, and offload LNG. FLNG plants have liquefaction and other LNG plant functionality, along with one or more LNG storage tanks. The design and positioning of the liquefaction unit can depend on the location of the LNG storage tank and, in particular, the liquid domecoupled to the pump tower of the LNG storage tank.

[0005] In a conventional tanker, the LNG storage tank is tilted slightly towards the rear, so it is preferable for the pump tower to be positioned also towards the rear of the storage tank for maximum product extraction. As a result, the LNG storage tank is normally positioned against a bulkhead (e.g., an aft bulkhead) to support the pump tower, and the pump tower is normally positioned in a predetermined location towards the rear of the tank. Because the liquid dome is overtop of the pump tower, the liquid dome’s position is thus dependent on the location of the pump tower and normally toward the rear of the LNG storage tank.Summary

[0006] One example of the present disclosure can include a floating gas plant, optionally a floating natural gas plant, comprising a deck. The floating gas plant may be a floating liquefaction plant (FLNG) for converting natural gas into liquefied natural gas, or a floating regasification plant (FSRU) for converting liquefied natural gas into natural gas. The plant can include a liquefaction unit for converting natural gas into liquified natural gas. The floating gas plant comprises a topside unit, which optionally comprises at least one of: a processing unit, or a liquefaction unit, or a regasification unit, or a compression unit, or an injection unit, or a utility unit, or any combination thereof. The topside unit can be at least partially positioned above the deck. The floating gas plant can also include a storage tank for storing processed gas, such as liquified natural gas, where the storage tank is positioned below the deck. A pump tower can be disposed in the storage tank, such that a portion of the pump tower protrudes through a surface of the deck. The pump tower can be coupled to the deck for stability.

[0007] One or more examples include the floating gas plant of the previous paragraph, wherein the deck is reinforced to support the topside unit.

[0008] One or more examples include the floating gas plant of the previous paragraph, wherein the deck is reinforced with one or more longitudinal beams extending along a longitudinal direction of the deck and one or more transverse beams extending along a width of the deck.

[0009] One or more examples include the floating gas plant of the previous paragraph, wherein the longitudinal and transverse beams are directly connected to an underside of the deck, e.g. by welding and / or by mechanical fastening means.

[0010] One or more examples include the floating gas plant of any previous paragraph, wherein the pump tower is not coupled to any sidewalls of the storage tank.

[0011] One or more examples include the floating gas plant of any previous paragraph, wherein the storage tank includes a guide system coupled to the storage tank for receiving a bottom portion of the pump tower and controlling horizontal movement of the pump tower.

[0012] One or more examples include the floating gas plant of any previous paragraph, wherein the deck is a hull deck.

[0013] One or more examples include the floating gas plant of any previous paragraph, wherein the portion of the pump tower is coupled to the deck with screws, bolts, welds, and / or nails.

[0014] One or more examples include the floating gas plant of any previous paragraph, wherein the pump tower comprises a lattice frame that is square, rectangular, or triangular in shape.

[0015] One or more examples include the floating gas plant of any previous paragraph, wherein the pump tower spans substantially a height of the storage tank or greater.

[0016] One or more examples include the floating gas plant of any previous paragraph, wherein the pump tower is coupled to a liquid dome of the storage tank.

[0017] One or more examples include the floating gas plant of any previous paragraph, wherein the floating natural gas plant includes two or more storage tanks.

[0018] Another example of the present disclosure can include a storage tank for liquified natural gas. The storage tank can include a bottom surface, sidewalls coupled to the bottom surface, and an upper surface coupled to the sidewalls. The upper surface can include a liquid dome. A pump tower can be positioned in the storage tank and extend to the liquid dome. The pump tower is not coupled to any of the sidewalls of the storage tank.

[0019] One or more examples include the storage tank of the previous paragraph, wherein the pump tower is mechanically coupled to a deck using connection elements.

[0020] One or more examples include the storage tank of any previous paragraph, wherein the deck is reinforced to support a topside unit which optionally comprises at least one of: a processing unit, or a liquefaction unit, or a regasification unit, or a compression unit, or an injection unit, or a utility unit, or any combination thereof and wherein the deck is part of a liquid natural gas plant.

[0021] One or more examples include the storage tank of any previous paragraph, wherein the deck is reinforced to support a topside unit of the preceding paragraph and wherein the deck is part of a floating carbon capture and storage (FCCS) vessel or a floating production, storage, and offloading (FPSO) vessel configured for CO2processing. The storage tank may be for the storage of any liquefied gas, such as CO2, Hydrogen, or Ammonia, for example.

[0022] One or more examples include the storage tank of any previous paragraph, wherein the deck is reinforced with one or more longitudinal beams extending along a longitudinal direction of the deck and one or more transverse beams extending along a width of the deck.

[0023] One or more examples include the storage tank of the previous paragraph, wherein the longitudinal and transverse beams are directly connected to an underside of the deck, e.g. by welding and / or by mechanical fastening means.

[0024] One or more examples include the storage tank of any previous paragraph, wherein the deck is hull deck of a floating unit, and wherein the storage tank is separated from a bulkhead of the floating unit by a gap.

[0025] One or more examples include the storage tank of any previous paragraph, wherein the connection elements include screws, bolts, welds, and / or nails.

[0026] One or more examples include the storage tank of any previous paragraph, wherein the storage tank includes a guide system coupled to a bottom of the storage tank for receiving a bottom portion of the pump tower and controlling movement of the pump tower.

[0027] One or more examples include the storage tank of any previous paragraph, wherein the pump tower has a lattice frame that is square, rectangular, or triangular in shape.

[0028] One or more examples include the storage tank of any previous paragraph, wherein the pump tower spans substantially all of a height of the storage tank.

[0029] Still another example of the present disclosure can include a method. The method can include positioning a storage tank for liquified natural gas below a deck of a floating unit. The method can also include positioning a pump tower within the storage tank, such that the pump tower vertically extends through the storage tank to an opening at a top surface of the storage tank. The method can further include coupling a portion of the pump tower to the deck of the floating unit.

[0030] One or more examples include the method of the previous paragraph, wherein the pump tower is not coupled to any sidewalls of the storage tank.

[0031] One or more examples include the method of any previous paragraph, wherein the pump tower is coupled to the deck using screws, bolts, welds, or nails.

[0032] One or more examples include the method of any previous paragraph, and further comprise positioning a bottom portion of the pump tower within a guide system coupled to a bottom of the storage tank to control horizontal movement of the pump tower.

[0033] One or more examples include the method of any previous paragraph, wherein the deck is reinforced to support a liquefaction unit.

[0034] One or more examples include the method of any previous paragraph, wherein the deck is reinforced to support a topside unit which may comprise at least one of: a processing unit, or a liquefaction unit, or a regasification unit, or a compression unit, or an injection unit, or a utility unit, or any combination thereof. The deck may be part of a floating carbon capture and storage (FCCS) vessel or a floating production, storage, and offloading (FPSO) vessel configured for CO2processing.

[0035] One or more examples include the method described in one or more of the preceding paragraphs, wherein the deck is reinforced with one or more longitudinal beams extending along a longitudinal direction of the deck and one or more transverse beams extending along a width of the deck.

[0036] One or more examples include the method of the previous paragraph, wherein the longitudinal and transverse beams are directly connected to an underside of the deck, e.g. by welding and / or by mechanical fastening means.

[0037] One example of the present disclosure can include a floating natural gas (FLNG) plant comprising a deck. The FLNG plant can also include a liquefaction unit for converting natural gas into liquified natural gas. The liquefaction unit can be at least partially positioned above the deck. The FLNG plant can also include a storage tank for storing the liquified natural gas, where the storage tank is positioned below the deck. A pump tower can be disposed in the storage tank, such that a portion of the pump tower protrudes through a surface of the deck. The pump tower can be coupled to the deck for stability.

[0038] One or more examples include the FLNG plant of the previous paragraph, herein the deck is reinforced to support the liquefaction unit.

[0039] One or more examples include the FLNG plant of any previous paragraph, wherein the pump tower is not coupled to any sidewalls of the storage tank.

[0040] One or more examples include the FLNG plant of any previous paragraph, wherein the storage tank includes a guide system coupled to the storage tank for receiving a bottom portion of the pump tower and controlling horizontal movement of the pump tower.

[0041] One or more examples include the FLNG plant of any previous paragraph, wherein the deck is a hull deck.

[0042] One or more examples include the FLNG plant of any previous paragraph, wherein the portion of the pump tower is coupled to the deck with screws, bolts, welds, and / or nails.

[0043] One or more examples include the FLNG plant of any previous paragraph, wherein the pump tower comprises a lattice frame that is square, rectangular, or triangular in shape.

[0044] One or more examples include the FLNG plant of any previous paragraph, wherein the pump tower spans substantially a height of the storage tank or greater.

[0045] One or more examples include the FLNG plant of any previous paragraph, wherein the pump tower is coupled to a liquid dome of the storage tank.

[0046] One or more examples include the FLNG plant of any previous paragraph, wherein the floating natural gas plant includes two or more storage tanks.

[0047] Another example of the present disclosure can include a storage tank for liquified natural gas. The storage tank can include a bottom surface, sidewalls coupled to the bottom surface, and an upper surface coupled to the sidewalls. The upper surface can include a liquid dome. A pump tower can be positioned in the storage tank and extend to the liquid dome. The pump tower is not coupled to any of the sidewalls of the storage tank.

[0048] One or more examples include the storage tank of the previous paragraph, wherein the pump tower is mechanically coupled to a deck using connection elements.

[0049] One or more examples include the storage tank of any previous paragraph, wherein the deck is reinforced to support a liquefaction unit, and wherein the deck is part of a liquid natural gas (FLNG) plant.

[0050] One or more examples include the storage tank of any previous paragraph, wherein the deck is hull deck of a floating unit, and wherein the storage tank is separated from a bulkhead of the floating unit by a gap.

[0051] One or more examples include the storage tank of any previous paragraph, wherein the connection elements include screws, bolts, welds, and / or nails.

[0052] One or more examples include the storage tank of any previous paragraph, wherein the storage tank includes a guide system coupled to a bottom of the storage tank for receiving a bottom portion of the pump tower and controlling movement of the pump tower.

[0053] One or more examples include the storage tank of any previous paragraph, wherein the pump tower has a lattice frame that is square, rectangular, or triangular in shape.

[0054] One or more examples include the storage tank of any previous paragraph, wherein the pump tower spans substantially all of a height of the storage tank.

[0055] Still another example of the present disclosure can include a method. The method can include positioning a storage tank for liquified natural gas below a deck of a floating unit. The method can also include positioning a pump tower within the storage tank, such that the pump tower vertically extends through the storage tank to an openingat a top surface of the storage tank. The method can further include coupling a portion of the pump tower to the deck of the floating unit.

[0056] One or more examples include the method of the previous paragraph, wherein the pump tower is not coupled to any sidewalls of the storage tank.

[0057] One or more examples include the method of any previous paragraph, wherein the pump tower is coupled to the deck using screws, bolts, welds, or nails.

[0058] One or more examples include the method of any previous paragraph, and further comprise positioning a bottom portion of the pump tower within a guide system coupled to a bottom of the storage tank to control horizontal movement of the pump tower.Brief Description of the Drawings

[0059] FIG. 1 shows an example of a floating unit that includes a storage tank with a pump tower according to some aspects of the present disclosure.

[0060] FIG. 2 shows an example of a storage tank with a pump tower according to some aspects of the present disclosure.

[0061] FIG. 3 shows a flowchart of an example of a process for coupling a pump tower to a deck of a floating vessel according to some aspects of the present disclosure.

[0062] FIG. 4 shows a top-down view of an example of a floating unit 100 according to some aspects of the present disclosure.

[0063] FIG. 5 is a schematic diagram illustrating one example of how the deck of a floating unit may be structurally reinforced.Detailed Description

[0064] Certain aspects and features of the present disclosure relate to techniques for allowing a pump tower of a storage tank for liquified gas to be selectively positioned in any suitable location within the storage tank. For example, the storage tank can be positioned below a deck of a floating unit, such as a ship or platform. If the deck is a deck of a hull of a ship, it may be referred to as a hull deck. The deck can be reinforced with steel or another metal, concrete, or another suitably rigid structure. A pump tower can be positioned in the storage tank for use in pumping Liquefied Gas into and out of the storage tank. The pump tower can have a lattice frame that is square, rectangular, or triangular inshape. The pump tower may span substantially all of (e.g., 95% or more of) the height of the storage tank, so that it can reach the Liquefied Gas at the bottom of the storage tank. To install the pump tower, a bottom portion of the pump tower is slid into a guide system within the storage tank to help keep the pump tower substantially fixed in the horizontal plane, but allow the pump tower to be movable in the vertical plane. An upper portion of the pump tower can be coupled (e.g., mechanically affixed) to the deck to also help maintain the pump tower in position. By using the deck for stability, the pump tower can be positioned in any suitable location in the storage tank.

[0065] In a typical arrangement, a Liquefied Gas storage tank is positioned against a bulkhead of a floating vessel, such as a carrier vessel or floating liquified natural gas (FLNG) plant. When a pump tower is installed in the storage tank, it is normally coupled to the sidewall of the storage tank that is adjacent to the bulkhead, for example by screwing or bolting the pump tower to the sidewall. The sidewall, in turn, is coupled to the bulkhead. Thus, the pump tower is indirectly coupled to the bulkhead. Because the pump tower may be very heavy (e.g., 70 tons or more), coupling the pump tower to the bulkhead can provide the necessary support to carry the load of the pump tower. But that approach forces the pump tower to be positioned at a specific location in the storage tank, namely against the particular sidewall of the storage tank that contacts the bulkhead. If the pump tower is forced to be at that location, and that location turns out to be inconvenient or problematic, it can raise a variety of issues. For example, depending on the construction of the floating vessel and the location of the bulkhead, the pump tower may have to be positioned in a location that is tough to access and far from other components. This can make it difficult, expensive, and potentially dangerous to install the required piping runs to the storage tank and perform necessary maintenance.

[0066] Some examples of the present disclosure can overcome one or more of the abovementioned problems by using a deck (e.g., a reinforced deck) of a floating unit, rather than a sidewall of the storage tank coupled to a bulkhead, to provide the necessary support to carry the load of the pump tower. More specifically, the storage tank can be positioned below the deck. The storage tank can have an opening at a desired location for the pump tower. A corresponding opening can be made in the deck. The pump tower can then be lowered through the deck’s opening and the storage tank’s opening into aguide system (e.g., guide rails) within the storage tank. The guide system can help position the pump tower in the storage tank and control horizontal and / or vertical movement of the pump tower. An upper end of pump tower can then be coupled to the deck for support. In some examples, the top 5% or the top 10% of the pump tower may be considered the upper end of the pump tower. The upper end of the pump tower may be coupled to the deck with screws, bolts, welds, nails, and / or other connection elements. Because the deck may run above most or all of the storage tank, this approach may provide flexibility in selectively positioning the pump tower at a desired location in the storage tank.

[0067] Using the techniques described herein, the pump tank may not need to be positioned against a specific sidewall of the storage tank, or any sidewall of the storage tank at all, to obtain the necessary support for its load. This can allow the pump tower to be positioned at locations that are more convenient, accessible, and closer to other components, thereby reducing failures, safety hazards, and other issues. And because the pump tower no longer needs to be indirectly coupled to the bulkhead for stability, the storage tank can also positioned in other locations away from the bulkhead, thereby allowing for a greater number of options in positioning the storage tank on the floating unit.

[0068] These illustrative examples are given to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the disclosed concepts. The following sections describe various additional features and examples with reference to the drawings in which like numerals indicate like elements but, like the illustrative examples, should not be used to limit the present disclosure.

[0069] FIG. 1 shows an example of a floating unit 100 that includes a storage tank 104 with a pump tower 108 according to some aspects of the present disclosure. In this example, the floating unit 100 is a ship. But in other examples, the floating unit 100 may be a platform or another floating arrangement of equipment. The floating unit 100 can include one or more bulkheads 102a-c, which can help shape and support the floating unit 100. The bulkheads 102a-c may be formed from wood, metal, and / or any other suitable material.

[0070] The storage tank 104 can include a liquid 106, such as liquified natural gas (LNG). At least one sidewall 116 of the storage tank 104 can be coupled to a bulkhead for stability. For example, the sidewall 116 may be screwed or bolted to the bulkhead 102a for stability. The storage tank 104 can have any suitable shape. For example, the storage tank 104 may be prismatic or rectangular in shape.

[0071] The pump tower 108 can be positioned in the storage tank 104 for pumping the liquid into and out of the storage tank 104. The pump tower 108 can extend vertically (e.g., along the Y direction) through the storage tank 104 and through an opening 122 in a deck 118 of the floating unit 100, such that an upper portion of the pump tower 108 protrudes through a surface 130 of the deck 118. The deck 118 may be reinforced with metal such as steel, concrete, or any other suitable reinforcement material to provide sufficient support for the topside units 110, 112, which may may comprise one or more of: a processing unit, or a liquefaction unit, or a regasification unit, or a compression unit, or an injection unit, or a utility unit, or any combination thereof, on top of the deck 118. A topside unit typically measures over 10m wide and 10m long. Typical weights of topside units are in the order of several hundred tonnes, due to the equipment included to support their functions. A topside unit can comprise: one or more compressors, one or more heaters and / or coolers, one or more separation columns and / or scrubbers, one or more gas turbines, or any combination thereof. When reinforced in this way, the deck may be referred to as a reinforced deck. The pump tower 108 can be coupled to the deck 118 with one or more connection elements 120 such as screws, bolts, welds, and / or nails. This can help maintain the pump tower 108 in position within the storage tank 104 and provide stability to the pump tower 108.

[0072] The pump tower 108 can be coupled to the topside units 110, 112 by one or more pipe systems 114. The topside units 110, 112 can be positioned above the deck 118. Examples of the topside units 110, 112 may include a liquefaction plant and a process plant. If the floating unit 100 is a FLNG plant, the floating unit 100 can be coupled through piping 128 to a subsea well system that includes one or more subsea wellbores 124 for extracting the natural gas from a subterranean formation 126. The topside units 110, 112 can then convert the natural gas into liquified natural gas and store the liquified natural gas in the storage tank 104.

[0073] A processing unit includes equipment for processing a feed of gasified or liquefied gas in, to, or from, a gaseous form or a liquefied form. A processing unit includes equipment for changing properties of the gaseous or liquefied gas, such as one or more pumps, or one or more heat exchangers.

[0074] A liquefaction unit includes equipment for liquefying a gas stream. Such equipment may include one or more heat exchangers for cooling a flow of gas, one or more temperature and / or pressure control elements such as one or more valves or pressure sensors, one or more pressure changing components such as a pump or a compressor, or any combination thereof.

[0075] A regasification unit includes equipment that can work together to effectuate a regasification process on a liquefied gas stream. Such equipment may include one or more heat exchangers for applying heat to the liquefied gas stream, one or more fluid vaporizers for vaporizing the liquefied gas stream, one or more pumps, one or more heat exchangers, or any combination thereof.

[0076] A compression unit includes equipment for compressing a gas stream. Such equipment can include one or more pressure changing components such as pumps, turbines, compressors, pressure control elements, such as one or more valves or pressure sensors, or any combination thereof.

[0077] An injection unit may be used for carbon capture and storage operations and may include equipment for injecting gas for carbon capture and storage operations. Such equipment can include one or more pumps, one or more pressure control elements, such as one or more valves or pressure sensors, one or more dehydration units, one or more pressure changing components such as pumps, turbines, compressors, pressure control elements, such as one or more valves or pressure sensors, or any combination thereof.

[0078] A utility unit includes equipment for generating, distributing or otherwise providing services and resources required to support the operation of a processing facility of the floating gas plant. Such services may include thermal energy sources for use in processes, including steam or water, for providing heat for operations on the floating gas plant, one or more boilers for steam generation, one or more chillers for cooling, one or more cooling towers for heat rejection, one or more electrical distribution systems forpower distribution, one or more pumping stations for water supply, or any combination thereof.

[0079] In a conventional arrangement, the sidewall 116 of the storage tank 104 is positioned against and coupled to the bulkhead 102a, and the pump tower 108 is positioned against and coupled to the sidewall 116. Thus, the pump tower 108 is indirectly coupled to the bulkhead 102a. This conventional approach uses the bulkhead 102a to provide the necessary support for the pump tower 108, which can weigh several tons (e.g., 60 tons or more just for the frame, not including the equipment). However, this conventional approach also limits the position of the pump tower 108 to being against the sidewall 116, which can have negative consequences. In contrast, as shown in FIG. 1 , the techniques described herein involve positioning the storage tank 104 below the deck 118 and coupling the pump tower 108 to the deck 118. Because the deck 118 may span some or all of the length (Z direction) and / or width (X direction) of the storage tank 104, the pump tower 108 may be positioned in substantially any (X, Z) location inside the storage tank 104, including in positions away from some or all of the sidewalls. For example, the pump tower 108 may be positioned 1 meter (m) or more away from the sidewall 116, and is not coupled to the sidewall 116 with any type of connection element. In some examples, the pump tower 108 can be positioned away from all of the sidewalls of the storage tank 104 and, thus, may not be coupled to any of the sidewalls with connection elements. As long as suitable openings are made in the top of the storage tank 104 and the deck 118, the techniques described herein can allow for greater flexibility in positioning the pump tower 108 on the floating unit 100.

[0080] Using the techniques described herein, the design and layout of the floating unit 100 can be more flexible. For example, the design and layout of the topside units 110, 112 and other elements of the floating unit 100 can be determined in advance, without being constrained by the liquid dome position and the pump tower 108, since the liquid dome can be positioned in various places thanks to the flexibility of the positioning of the pump tower 108 inside the storage tank 104. Such flexibility can greatly simplify the implementation of a FLNG plant.

[0081] Although FIG. 1 shows a single storage tank 104 for simplicity, it will be appreciated that the floating unit 100 may have any number of storage tanks with theirown respective pump towers configured using the techniques described herein. For example, the floating unit 100 may include two storage tanks with their own respective pump towers positioned in different locations in their respective storage tanks depending on the configuration of the topside units 110, 112 and other equipment on the surface 130 of the deck 118.

[0082] Turning now to FIG. 2, shown is an example of a storage tank 104 with a pump tower 108 according to some aspects of the present disclosure. The storage tank 104 can be formed from a series of layers, generally shown at 206. For example, the storage tank 104 can include a first membrane layer, a first insulation layer surrounding the first membrane layer, a second membrane layer surrounding the first insulation layer, and a second insulation layer surrounding the second membrane layer. The first membrane layer can store the LNG and may be fabricated from Invar. The second membrane layer may also be fabricated from Invar. The second membrane layer and the secondary insulation layer can serve as a backup in the event of a leak in the primary barrier (e.g., the first membrane layer).

[0083] The storage tank 104 can also include a guide system 202, which may be coupled to the bottom 208 of the storage tank 104. The guide system 202 can include one or more guide rails on one or more sides of the pump tower 108. The guide system 202 can help maintain the pump tower 108 in position, for example by controlling the horizontal (in the X direction) and / or lateral (in the Z direction) movement of the bottom portion of the pump tower 108 in response to waves, wind, or other stimuli.

[0084] The pump tower 108 can have a rigid frame of any suitable shape and size to hold the pumps, pipes, and other equipment located on the pump tower 108. For example, the pump tower 108 can have a lattice frame that is square, rectangular, or triangular in shape. The pump tower 108 can be inserted into the guide system 202 from the top down, through an opening at the top of the storage tank 104. In some examples, the opening in the top of the storage tank 104 can correspond to a liquid dome 218 and, thus, the pump tower 108 may be coupled to or part of the liquid dome 218. The opening and the guide system 202 can be aligned with one another at a desired location in the storage tank 104 for receiving the pump tower 108. The pump tower 108 can spansubstantially all of the height (Y direction) of the storage tank 104. This may allow the pump tower 108 to pump more of the liquid out of the storage tank 104.

[0085] In some examples, the pump tower 108 can be positioned away from one or more of the sidewalls of the storage tank 104 (e.g., all the walls of the storage tank) such that the pump tower 108 is separated from those sidewalls by a gap 214. Accordingly, the pump tower 108 may not be coupled to those sidewalls with connection elements. And in some examples, because the bulkhead 212 is no longer needed to support the pump tower 108, the storage tank 104 may be positioned away from the bulkhead 212 such that the storage tank 104 is separated from the bulkhead 212 by a gap 216. Accordingly, the storage tank 104 may not be coupled to the bulkhead with connection elements. This may allow for greater flexibility in positioning the storage tank 104 on the floating unit.

[0086] Turning now to FIG. 3, shown is a flowchart of an example of a process for coupling a pump tower to a deck of a floating vessel according to some aspects of the present disclosure. Other examples may involve more operations, fewer operations, different operations, or a different order of operations than is shown in FIG. 3. The operations of FIG. 4 are described below with reference to the components of FIGS. 1-2 described above.

[0087] In block 302, a storage tank 104 is positioned below a deck 118 of a floating unit 100. The deck may be reinforced with steel or other elements to support a liquefaction unit or other topside units. Prior to being positioned on the floating unit, the storage tank 104 may be prefabricated with a hole and / or liquid dome at a desired location through which a pump tower 108 will extend. Alternatively, the hole and / or liquid dome may be cut into the storage tank 104 at a desired location after the storage tank 104 is positioned on the floating unit 100.

[0088] In block 304, a pump tower 108 is positioned within the storage tank 104. For example, the pump tower 108 can be inserted through the opening 122 in the storage tank 104 and downwardly into the storage tank 104. As a result, the pump tower 108 can extend vertically through the storage tank 104 to the opening 122 at the top of the storage tank 104.

[0089] In block 306, the pump tower 108 is slid into a guide system 202 coupled tothe storage tank 104, for example such that a bottom portion of the pump tower 108 is positioned within the guide system 202. The guide system 202 can control the horizontal movement of the pump tower 108. The opening 122 in the storage tank 104 can be aligned with the guide system 202, so that the opening 122 is overtop of the guide system 202 and the two share a central axis. The opening 122 and the guide system 202 can position the pump tower 108 away from some or all of the sidewalls of the storage tank 104. The pump tower 108 may thus not be coupled to any of the sidewalls of the storage tank 104 by connector elements (e.g., screws, bolts, nails, etc.).

[0090] In block 308, an upper portion of the pump tower 108 is coupled to the deck 118 of the floating unit 100. For instance, a location within the upper 10% of the pump tower 108 can be coupled to the deck 118 by connector elements. Coupling the upper portion of the pump tower 108 to the deck 118 can help mechanically affix the pump tower 108 to the deck 118, which can provide suitable support to carry the load of the pump tower 108.

[0091] FIG. 4 shows a top-down view of an example of a floating unit 100 according to some aspects of the present disclosure. The floating unit 100 can include a deck, as shown by the hatched lines in FIG. 4. The hatched lines can represent steel beams or other reinforcement mechanisms in the deck.

[0092] The floating unit 100 can include a storage tank 104 positioned below a surface 130 of the deck, as represented by the dashed outline of the storage tank 104. A pump tower 108 can extend from an interior of the storage tank 104 through an opening 122 in the surface 130 of the deck. The pump tower 108 can include pump system equipment (e.g., a pump, a motor, a cooling system, valves, sensors, etc.). At least some of the pump system equipment can be coupled to one or more topside units 110, 112 by one or more pipe systems 114. The pump tower 108 itself can be coupled to the surface 130 of the deck via one or more connection elements 120.

[0093] As represented by the four-way arrow pointing in the X and Z directions, the pump tower 108 can be positioned at any desired (X, Z) location in the storage tank 104, as long as corresponding openings are made in both the storage tank 104 and the deck. This may include locations that are away from one or more of the sidewalls of the storage tank 104, for example such that the pump tower 108 does not contact any of the sidewallsof the storage tank 104 and is not mechanically fastened to any of the sidewalls of the storage tank 104. Using these techniques, there can be greater flexibility in positioning the storage tank 104 on the floating unit 100, which in turn may reduce costs, danger, complexity, and maintenance complications associated with connecting and maintaining the storage tank 104 and / or pump tower 108.

[0094] FIG. 5 is a schematic diagram illustrating one example of how the main deck may be structurally reinforced. In this example, the vessel is a floating liquefied natural gas (FLNG) unit 400, which may be a platform or substantially ship-shaped in form, and includes one or more topside units 410 mounted on the deck. The topside units 410 may comprise one or more of: a processing unit, or a liquefaction unit, or a regasification unit, or a compression unit, or an injection unit, or a utility unit, or any combination thereof. The topside unit 410 may further or alternatively comprise a CO2compression unit or injection unit for carbon capture and storage operations.

[0095] The reinforcement structure may be formed by a system of steel beams located beneath plating which forms the main structural platform of the deck. These beams can include longitudinal beams 420 aligned along the length of the hull and / or transverse beams 440 aligned across its width. The longitudinal and transverse beams 420,440 may be fixed together to form a rectangular grid or framework. The plating may be welded directly to the upper surfaces of the beam framework. The longitudinal and transverse beams 420,440 may be aligned with, and located above, internal structural elements of the hull such as girders and bulkheads allowing vertical loads from the processing units 410 to be transferred into the primary load bearing structures of the vessel.

[0096] Additional intermediate beams 460 may be incorporated into the grid formed by the longitudinal and transverse beams 420,440 described above. These beams 460 may be welded to the underside of the deck plating and connected at their ends to the sides of adjacent longitudinal or transverse beams 420,440 within the grid. Unlike the primary beams 420,440, the intermediate beams 460 may not be intended to transfer load directly into the bulkheads or girders. Instead, they may function to reduce local deformation of the deck plating between the longitudinal and transverse beams 420,440 and improve load distribution.

[0097] During operation in partially filled conditions, wave-induced motion of the hull causes movement of liquid within the tank, resulting in sloshing loads. These loads act on a pump tower submerged in the liquid and generate lateral forces where the tower connects to the deck. The reinforcement of the deck provides strength and stiffness to absorb and redistribute these forces, thus allowing the tower to be supported through its connection to the deck and reducing a need to position the tower adjacent a bulkhead.

[0098] The foregoing description of certain examples, including illustrated examples, has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Numerous modifications, adaptations, and uses thereof will be apparent to those skilled in the art without departing from the scope of the disclosure. For instance, any examples described herein can be combined with any other examples to yield further examples.

Claims

Claims1 . A floating gas plant, comprising: a deck; a topside unit, which comprises at least one of: a processing unit, or a liquefaction unit, or a regasification unit, or a compression unit, or an injection unit, or a utility unit, or any combination thereof, wherein the topside unit is at least partially positioned above the deck; a storage tank for storing the liquified gas, wherein the storage tank is positioned below the deck; and a pump tower disposed in the storage tank, wherein a portion of the pump tower protrudes through a surface of the deck and is coupled to the deck for stability (e.g. with screws, bolts, welds, and / or nails).

2. The floating gas plant of claim 1 , wherein the deck is reinforced to support the topside unit.

3. The floating gas plant of claim 1 , wherein the pump tower is not coupled to any sidewalls of the storage tank.

4. The floating gas plant of claim 1 , wherein the storage tank includes a guide system coupled to the storage tank for receiving a bottom portion of the pump tower and controlling horizontal movement of the pump tower.

5. The floating gas plant of claim 1 , wherein the deck is a hull deck.

6. The floating gas plant of claim 1 , wherein the pump tower spans substantially a height of the storage tank or greater, optionally, wherein the pump tower comprises a lattice frame that is square, rectangular, or triangular in shape.

7. The floating gas plant of claim 1 , wherein the pump tower is coupled to a liquid dome of the storage tank.

8. The floating gas plant of claim 1 , wherein the floating natural gas plant includes two or more storage tanks.

9. A storage tank for liquified gas, the storage tank comprising: a bottom surface; sidewalls coupled to the bottom surface; an upper surface coupled to the sidewalls, the upper surface including a liquid dome; and a pump tower positioned in the storage tank and extending to the liquid dome, wherein the pump tower is not coupled to any of the sidewalls of the storage tank; wherein the pump tower is mechanically coupled to a deck using connection elements; and wherein a topside unit is at least partially positioned above the deck, and wherein the deck is part of a floating gas plant.11 . The storage tank of claim 10, wherein the topside unit comprises at least one of: a processing unit, or a liquefaction unit, or a regasification unit, or a compression unit, or an injection unit, or a utility unit, or any combination thereof.

12. The storage tank of claim 10, wherein the deck is hull deck of a floating unit, and wherein the storage tank is separated from a bulkhead of the floating unit by a gap.

13. The storage tank of claim 9, wherein the storage tank includes a guide system coupled to a bottom of the storage tank for receiving a bottom portion of the pump tower and controlling movement of the pump tower.

14. A method comprising: positioning a storage tank for liquified gas below a deck of a floating unit;positioning a topside unit at least partially above the deck of the floating unit; positioning a pump tower within the storage tank, such that the pump tower vertically extends through the storage tank to an opening at a top surface of the storage tank; and coupling a portion of the pump tower to the deck of the floating unit; optionally, wherein the pump tower is not coupled to any sidewalls of the storage tank.

15. The method of claim 14, wherein the topside unit comprises at least one of: a processing unit, or a liquefaction unit, or a regasification unit, or a compression unit, or an injection unit, or a utility unit, or any combination thereof; the method optionally further comprising: positioning a bottom portion of the pump tower within a guide system coupled to a bottom of the storage tank to control horizontal movement of the pump tower.

Images