Method for charging and gas testing in a liquefied gas storage installation

Abstract

A method of gassing, the method of gassing comprising: introducing a flow of liquefied gas in liquid phase (25) into a first storage tank (10A) to cool the first tank and vaporize the liquefied gas in liquid phase inside the first tank, simultaneously with the introduction of the flow of liquefied gas in liquid phase (25) into the first storage tank (10A), conveying a flow of liquefied gas in gaseous phase (26, 126) from an upper portion of the first tank to an upper portion of a second storage tank (10B), said flow of liquefied gas in gaseous phase (26, 126) being generated by vaporization of the liquefied gas in liquid phase, and allowing a flow of inert gas (27) to be discharged from a lower portion of the second tank (10B), so that the liquefied gas in gaseous phase (21) replaces the inert gas (22) at least in the upper portion of the second storage tank (10B).

Description

Technical Field

[0001] This invention relates to the field of liquefied gas storage facilities, and particularly to facilities on floating structures such as liquefied natural gas carriers.

[0002] Liquefied gas storage facilities, especially those used for storing liquefied natural gas (LNG), can be onshore storage facilities, seabed storage facilities, or facilities transported on coastal or deep-water floating structures, particularly LNG carriers, floating storage and regasification units (FSRUs), and floating production, storage and unloading (FPSO) units.

[0003] Liquefied gases can be combustible gases, especially liquefied natural gas (LNG) or liquefied petroleum gas (LPG). Background Technology

[0004] Putting LNG storage tanks into service after manufacturing or reactivating them after major overhaul involves a series of operations known as drying, inerting, filling, cooling, and loading.

[0005] Specifically, these operations are conducted during gas testing, which is performed before an LNG vessel is put into or recommissioned to verify the proper operation of the storage tanks and cargo handling systems at cryogenic temperatures. A more complete description of gas testing and best practices can be found in the publication “Guide for planning Gas Trials for LNG Vessels” in the SIGTTO information document (2019 edition) ISBN 13:978-1-85609-810-6 (9781856098106).

[0006] Specifically, during offshore operations, gas testing is typically conducted simultaneously in multiple storage tanks, specifically:

[0007] - The storage tank is filled with gaseous gas generated by forced gasification in the liquefied natural gas gasification unit;

[0008] The storage tank is then cooled using a liquid-gas flow.

[0009] All of these offshore operations consume liquefied natural gas previously loaded into separate tanks and produce vaporized gas, i.e., liquefied gas in the gaseous phase, which cannot be stored on board. Conventional techniques for handling this vaporized gas include reliquefaction, consumption in propulsion engines, combustion in combustion units, and / or emission into the atmosphere. Summary of the Invention

[0010] Some aspects of the present invention are based on the observation that gas testing, particularly inflation and cooling operations, produces a large amount of evaporated gas, and ideally these gases should be reduced to facilitate processing, conserve liquefied gas, and / or reduce gas emissions into the atmosphere.

[0011] One concept behind this invention involves using evaporated gas generated during the cooling of one tank to inflate another tank, particularly during gas testing involving multiple tanks in a liquefied gas storage facility.

[0012] Therefore, the present invention proposes a method for filling storage tanks in a liquefied gas storage facility, wherein the liquefied gas storage facility is preferably installed on a floating structure, and the method includes:

[0013] The liquefied gas storage facility is put into a ready state. The liquefied gas storage facility includes multiple storage tanks and at least one manifold. The at least one manifold is connected in parallel to the top portion of each storage tank. The first storage tank in the ready state is filled with gaseous liquefied gas. The temperature of the gaseous liquefied gas in the first tank is higher than the liquid-gas equilibrium temperature of the liquefied gas. The second storage tank in the ready state is filled with inert gas.

[0014] A stream of liquid-phase liquefied gas is injected into the first tank to cool the first tank and to partially or completely vaporize the liquid-phase liquefied gas in the first tank.

[0015] When injecting a liquid-phase liquefied gas stream into the first tank, a gaseous liquefied gas stream generated by the vaporization of the liquid-phase liquefied gas is transported from the top portion of the first tank to the top portion of the second tank through at least one manifold connected to the top portion of each storage tank in the storage tank. The density of the gaseous liquefied gas is lower than that of the inert gas.

[0016] An inert gas stream is released from the bottom portion of the second tank under pressure from the gaseous liquefied gas stream, causing the gaseous liquefied gas to replace the inert gas at least in the top portion of the second storage tank.

[0017] These features enable multiple storage tanks to be filled and cooled sequentially or partially sequentially, resulting in less evaporating gas than conventional synchronous processes.

[0018] According to an advantageous implementation, the method may have one or more of the following features:

[0019] The connection used to transfer the gaseous liquefied gas stream from the first storage tank to the second storage tank can be made in a variety of different ways.

[0020] According to one embodiment, at least one manifold is a maintenance manifold connected in parallel to the top portion of each storage tank in the storage tank via a corresponding first isolation valve, transmitting a gaseous liquefied gas flow from the top portion of the first storage tank to the maintenance manifold via a first isolation valve associated with the first tank, and / or transmitting a gaseous liquefied gas flow from the maintenance manifold to the top portion of the second tank via a first isolation valve associated with the second tank.

[0021] Preferably, the maintenance manifold is not insulated. In particular, the maintenance manifold may be a manifold connected to an inert gas production unit typically used for can inerting.

[0022] According to one embodiment, at least one manifold further includes a vaporization manifold, which is insulated, and is connected in parallel to the top portion of each storage tank in the storage tank via a corresponding second isolation valve. The vaporization manifold is connected in series with a maintenance manifold, and the vaporized liquefied gas stream is sequentially delivered through a first isolation valve associated with a first tank, the maintenance manifold, the vaporization manifold, and a second isolation valve associated with a second tank, or the vaporized liquefied gas stream is sequentially delivered through a second isolation valve associated with a first tank, the vaporization manifold, the maintenance manifold, and a first isolation valve associated with a second tank.

[0023] The flow of gaseous liquefied gas from the first storage tank to the second storage tank can be achieved in various different ways.

[0024] According to one embodiment, the gaseous liquefied gas stream flows from the top portion of the first storage tank to the top portion of the second storage tank via natural convection. These features enable passive flow without additional energy consumption.

[0025] According to one embodiment, the liquefied gas storage facility further includes a gas reheating device having an inlet connected to one of the maintenance manifold and the vaporization manifold, and an outlet connected to the other of the maintenance manifold and the vaporization manifold, for reheating the gaseous liquefied gas stream by passing it through the gas reheating device before it reaches the top portion of the second tank. These features enable the recovery of relatively cold evaporated gas, particularly when the cooling operation of the first tank is in an advanced state, allowing the recovery of evaporated gas obtained in the first tank.

[0026] According to one embodiment, the liquefied gas storage facility further includes a gas reheating device having an inlet connected to one of a maintenance manifold and a vaporization manifold, and an outlet connected to the other of the maintenance manifold and the vaporization manifold.

[0027] Furthermore, during the first flow phase, the gaseous liquefied gas flowed from the top portion of the first storage tank to the top portion of the second storage tank via natural convection, and

[0028] During the second flow stage, the gaseous liquefied gas stream is also passed through a gas reheating device to reheat the gaseous liquefied gas stream before it reaches the top portion of the second tank.

[0029] According to one embodiment, the method further includes the following steps:

[0030] The temperature of the liquefied gas exiting the first tank during the first flow stage is monitored; and

[0031] When the temperature of the gaseous liquefied gas meets the predetermined standard, the gaseous liquefied gas flow is switched to the reheating device.

[0032] These features enable the establishment of natural flow at the start of the cooling operation of the first tank until a predetermined criterion, such as a temperature threshold, is met. Below this threshold, the gaseous liquefied gas becomes too dense to continue the filling operation. The flow is then switched to the reheater to continue filling the second storage tank.

[0033] Liquid-phase liquefied gas streams can be generated in a variety of different ways, such as outside or inside a liquefied gas storage facility. According to some embodiments, liquid-phase liquefied gas streams are delivered from a shore terminal or refueling vessel, to which the liquefied gas storage facility is connected.

[0034] According to one embodiment, the liquefied gas storage facility includes a third storage tank and an injection manifold connected in parallel to each of the storage tanks. The third storage tank, in a ready state, is partially or completely filled with liquid-phase liquefied gas, and the liquid-phase liquefied gas is pumped into the third tank and delivered to the first tank by the injection manifold.

[0035] According to one embodiment, a liquid-phase liquefied gas stream is injected into a first storage tank via an injection device.

[0036] Inert gases can be removed in a variety of ways. According to one embodiment, a liquefied gas storage facility includes a liquid manifold and a mast riser connected to the liquid manifold, which is connected in parallel to the bottom portion of each storage tank in the storage tank, and the liquid manifold delivers the inert gas stream leaving the second tank to the mast riser.

[0037] According to one embodiment, the present invention also provides a method for conducting gas testing in a liquefied gas storage facility located on a floating structure, the gas testing comprising:

[0038] The second storage tank is inflated using the method described above, and after the second storage tank has been inflated,

[0039] The liquid-phase liquefied gas stream is injected into the second storage tank to cool the second storage tank.

[0040] As described above, the other storage tank can be pressurized while the second storage tank is being cooled. This allows a certain amount of vaporized gas generated during the cooling operation of the second storage tank to be utilized, thus reducing the total amount of vaporized gas generated compared to conventional synchronous processes.

[0041] According to one embodiment, the present invention also provides a liquefied gas storage facility, preferably supported on a floating structure, the liquefied gas storage facility comprising: a plurality of storage tanks,

[0042] A maintenance manifold, which is connected in parallel to the top portion of each storage tank in the storage tank via a corresponding first isolation valve;

[0043] A vaporization manifold, which is connected in parallel to the top portion of each storage tank in the storage tank via a corresponding second isolation valve, is insulated.

[0044] A liquid manifold, connected in parallel to the bottom portion of each storage tank in the storage tank system, is insulated; and

[0045] The mast riser connects to the liquid manifold;

[0046] The first isolation valve can be switched to selectively connect the maintenance manifold to the top portion of the first storage tank in the storage tank, so that a gaseous liquefied gas flow is transmitted from the first storage tank to the maintenance manifold through the first isolation valve associated with the first storage tank.

[0047] According to an advantageous embodiment, such a liquefied gas storage facility may have one or more of the following features.

[0048] According to one embodiment, each storage tank includes a filling line and a vaporization line, the filling line being connected to a liquid manifold, the vaporization line leading to the top portion of the storage tank, and the vaporization line being connected in parallel to a maintenance manifold via a first isolation valve associated with the storage tank, and the vaporization line being connected in parallel to the vaporization manifold via a second isolation valve associated with the storage tank.

[0049] According to one embodiment, the vaporization manifold and the maintenance manifold are connected in series.

[0050] The second isolation valve can be switched to selectively connect the vaporization manifold to the top portion of the second storage tank in the storage tank, so that the vapor-phase liquefied gas flow is delivered from the first storage tank sequentially through the first isolation valve associated with the first storage tank, the maintenance manifold, the vaporization manifold, and the second isolation valve associated with the second storage tank to the second storage tank.

[0051] According to one embodiment, the liquefied gas storage facility further includes an injection manifold and an injection device, the injection manifold being connected in parallel to each storage tank in the storage tank, the injection device being disposed in the top portion of each tank in the tank, and the injection device being connected to the injection manifold.

[0052] According to one implementation, the liquefied gas is liquefied natural gas.

[0053] According to one embodiment, the floating structure is a vessel for transporting liquefied gases. Such a vessel for transporting liquefied gases may include a twin hull and storage tanks arranged within the twin hulls. According to one embodiment, the storage tanks are manufactured using membrane technology, and the twin hulls include an inner hull forming the load-bearing walls of the storage tanks.

[0054] According to one embodiment, the present invention also provides a test system for performing gas testing, the system comprising: the aforementioned liquefied gas storage facility; an insulated pipe arranged to connect a liquid manifold or jet manifold to an onshore terminal; and a pump for driving liquid-phase liquefied gas from the onshore terminal through the insulated pipe to the liquid manifold or jet manifold. Attached Figure Description

[0055] The invention will be better understood and its additional objects, details, features and advantages will be more clearly set forth in the following detailed description of several specific embodiments of the invention, given only by way of non-limiting example and with reference to the accompanying drawings.

[0056] [ Figure 1 ] Figure 1 This is a diagram illustrating a portion of a liquefied gas storage and processing system in which the method according to the invention can be implemented.

[0057] [ Figure 2 ] Figure 2 Is with Figure 1 Similar images, Figure 2 A liquefied gas storage and processing system is shown prior to the filling operation of the tank.

[0058] [ Figure 3 ] Figure 3 Is with Figure 1 Similar images, Figure 3 A liquefied gas storage and processing system is shown in the first stage of the tank filling operation.

[0059] [ Figure 4 ] Figure 4 It is a graph showing the change of the tank's state over time during the inflation operation.

[0060] [ Figure 5 ] Figure 5 Is with Figure 1 Similar images, Figure 5 The liquefied gas storage and processing system is shown in the second stage of the tank filling operation.

[0061] [ Figure 6 ] Figure 6 Is with Figure 1 Similar images, Figure 6 The diagram shows a liquefied gas storage and processing system in the third stage of the tank filling operation.

[0062] [ Figure 7 ] Figure 7 This is a timing diagram illustrating a test procedure implemented in a liquefied gas storage and processing system.

[0063] [ Figure 8 ] Figure 8 This is a cross-sectional schematic diagram of a liquefied natural gas carrier connected to a loading / unloading terminal. Detailed Implementation

[0064] Figure 1 This is a schematic diagram of an LNG storage facility that can be transported on a floating structure, such as a liquefied natural gas carrier.

[0065] Three storage tanks, 10A, 10B, and 10C, are shown as examples; however, this number can be more or less. The tanks can be arranged continuously along the length of the hull or otherwise. The storage tanks have sealed and insulated walls, which can be manufactured using various technologies such as double-membrane technology.

[0066] The cargo handling system connecting all the tanks is partially shown. Each storage tank 10A to 10C specifically includes:

[0067] - Fill line 9, which is connected to the liquid manifold 1;

[0068] - Vaporized gas line 6, which leads to the top portion of the storage tank, and is connected in parallel to maintenance manifold 4 via first isolation valve 11 and to vaporized gas manifold 2 via second isolation valve 12.

[0069] - One or more spray bars 5, which lead to the top portion of the storage tank and are connected to the spray manifold 3.

[0070] - Injection pump 7, which is connected to injection manifold 3 via pumping line 8.

[0071] Other components, not shown, may be present, such as one or more unloading pumps in each storage tank.

[0072] The aforementioned manifold can be connected to other fluid circuits, such as a liquid manifold 1 connecting the filling line 9 of all tanks and a jet manifold 3 connecting the jet rods 5 of all tanks. For example, as shown by links 16 and 17, the liquid manifold 1 and the jet manifold 3 are connected to a transfer circuit for conveying fluid to or from a shore terminal or another vessel.

[0073] To reduce the number of lines passing through the tank wall, a single vaporization line 6 is used to connect the maintenance manifold 4 and the vaporization manifold 2 in parallel to the tank interior. Alternatively, two separate vaporization lines can be provided.

[0074] The injection manifold 3, liquid manifold 1, and vaporization manifold 2 are designed to deliver cold fluids and are therefore preferably insulated. In contrast, the maintenance manifold 4 has little or no insulation because it is typically used to deliver inert gas from an inert gas production unit (not shown) for inerting operations in tanks and pipelines.

[0075] Figure 1 An angled connector 19 is also shown, which connects one end of the maintenance manifold 4 to the vaporization manifold 2 to form a particularly long flow path. This angled connector is referenced below. Figure 3 Use as explained. The angled connector 19 is optional.

[0076] Gas reheater 14 is connected to maintenance manifold 4 via an isolation valve, for example at the outlet of gas reheater 14, and to vaporization manifold 2, for example at the inlet of gas reheater 14. Similarly, vaporization unit 15 is connected to injection manifold 3 via an isolation valve, for example at the inlet of vaporization unit 15, and to vaporization manifold 2, for example at the outlet of vaporization unit 15.

[0077] Other components, not shown, can be connected to different manifolds. For example, vaporization manifold 2 can be connected to a device powered by gas phase gas, as shown in connection 18, such as a combustion unit or a propulsion engine.

[0078] The following is for reference Figures 2 to 6 This describes the simultaneous operation of cooling tank 10A and purging tank 10B. To do this, the facility is brought into a ready state by inerting tank 10B and purging tank 10A. Any suitable method can be used to perform these operations.

[0079] By convention, the thick lines in the diagram represent pipes or loops used to transport fluids used in the system. The arrows in the diagram indicate the flow of liquid or gas in the pipe below the horizontal arrow or in the pipe to the left of the vertical arrow.

[0080] exist Figure 2 In the preparatory state shown, tank 10A is subsequently filled with gaseous natural gas 21 at ambient temperature, and tank 10B is filled with an inert gas 22 at ambient temperature, such as nitrogen or carbon dioxide-rich gas produced by the combustion of petroleum.

[0081] exist Figure 2 The image shows a partially filled storage tank of liquid-phase liquefied gas in a preparatory state, indicated by dashed lines. Injection manifold 3 is also connected to this additional storage tank.

[0082] Figure 3 The first stage is shown, in which tank 10A is simultaneously cooled and tank 10B is inflated.

[0083] LNG stream 25 is injected into tank 10A via injection manifold 3 and sprayed by injection rod 5 to cool tank 10A. The LNG vaporizes, releasing its vaporization potential into tank 10A, which produces excess gaseous natural gas. This excess gaseous natural gas must be discharged from tank 10A during the generation of the gas to avoid increasing the pressure in tank 10A. For this purpose, a flow path is created to transport gaseous natural gas stream 26 from tank 10A to tank 10B to prime tank 10B.

[0084] like Figure 3 As shown, LNG stream 25 can be pumped to another tank and delivered to tank 10A via injection manifold 3.

[0085] Since filling tank 10B requires a gas lighter than inert gas 22, it is advantageous to use a flow path for a gaseous natural gas stream 26 to force the inert gas 22 to the bottom portion of tank 10B. This flow path utilizes a long, uninsulated maintenance manifold 4, allowing for some heat exchange with the ambient atmosphere, thus helping to warm the gaseous natural gas stream 26 before it reaches tank 10B. For this purpose, arrow 26 shows the flow path from tank 10A via vaporization line 6 and isolation valve 11 to maintenance manifold 4, running along the entire length of maintenance manifold 4 until the angled connector 19, and continuing into vaporization manifold 2 until vaporization line 6 of tank 10B.

[0086] This flow path can be configured using isolation valves 11 and 12 in the following manner:

[0087] - Close all isolation valves 11 except for the isolation valve of tank 10A;

[0088] - Close all isolation valves 12 except for the isolation valve of tank 10B.

[0089] Other flow paths are also possible. For example, the flow path described above can be reversed, starting from vaporization manifold 2 and ending at maintenance manifold 4. This reverse path can be configured using isolation valves 11 and 12 in the following manner:

[0090] - Close all isolation valves 12 except for the isolation valve of tank 10A;

[0091] - Close all isolation valves 11 except for the isolation valve of tank 10B.

[0092] The alternative, shorter flow path is indicated by arrow 126. In this case, the flow path exits tank 10A via the vaporization line 6 and isolation valve 11 of tank 10A toward the maintenance manifold 4, and re-enters tank 10B via the vaporization line 6 and isolation valve 11 of tank 10B.

[0093] During the inflation operation of tank 10B, a gaseous natural gas flow 26 or 126 propels inert gas 22 toward the bottom portion of tank 10B. To create a pressure differential that allows the gaseous natural gas flow 26 or 126 to enter tank 10B, the pressure in tank 10B is maintained below the pressure in tank 10A by allowing an inert gas flow 27 to exit via filling line 9, liquid manifold 1, and mast riser 13 connected to liquid manifold 1. This is preferably on the foremast, furthest from the ship's wheelhouse. The relative pressure in tank 10B during inflation can be, for example, about 60 mbar (6 kPa), while the relative pressure in tank 10A can be, for example, between 150 mbar (15 kPa) and 180 mbar (18 kPa).

[0094] Figure 4 This is a graph showing the evolution of the thermodynamic state of tank 10A during cooling operations. The x-axis represents time in hours. The right y-axis represents the temperature of the gas phase in tank 10A in degrees Celsius (°C), with curve 41 showing the evolution of the gas phase temperature from ambient temperature (30°C in this example) to approximately -130°C. The left y-axis represents the mass flow rate of the evaporated gas in kg / h, with curve 42 showing the evolution of the mass flow rate of the evaporated gas leaving tank 10A from the initial zero flow rate at the start of operation. Cooling operations for large-capacity tanks may take approximately 15 hours.

[0095] Figure 4 The quantitative values ​​given are purely illustrative. These values ​​clearly demonstrate the following trend: at the start of the cooling operation, the generated evaporated gas is relatively hot and therefore not very dense, and the yield of said gas is initially low but increases rapidly. After a certain period of time, for example... Figure 4 After about 2 hours, the evaporated gas reaches a temperature that is too cold, for example... Figure 4 The temperature in the tank is approximately -25°C, causing the evaporated gas to become too dense to be directly filled into tank 10B.

[0096] In this case, it may be necessary to end the reference. Figure 3 The first stage described and the second stage operation starting with gas reheater 14, as... Figure 5 As shown.

[0097] exist Figure 5 In this process, the LNG stream 25 and the inert gas stream 27 continue as previously described, but the gaseous natural gas stream 26 is conveyed along a separate flow path through the gas reheater 14, where it is heated to a suitable temperature, for example, about 20°C, to continue purging tank 10B. The heated natural gas stream is indicated by arrow 28. Figure 5 In the example shown, the flow path leaves tank 10A via vaporization line 6 and isolation valve 12, passes through vaporization manifold 2, gas reheater 14, maintenance manifold 4, isolation valve 11 of tank 10B, and vaporization line 6 to reach tank 10B.

[0098] Switching the gaseous natural gas stream 26 to the gas reheater 14 to initiate the second stage can be manual or automatic. The criterion for ending the first stage and starting the second stage can be temperature or gaseous density. This criterion can be monitored by a human operator or executed automatically by the control system.

[0099] If the amount of vaporized gas produced during the entire cooling operation of tank 10A is excessive relative to the progress of the gas filling operation of tank 10B, the excess gaseous natural gas can be directed, for example, via connection 18, to a gas-powered device.

[0100] The two stages described above for purging storage tank 10B allow the use of evaporating gases that are inevitably generated during the cooling operation of storage tank 10A. However, the two stages are not essential. For example, if purging of tank 10B is completed before the temperature of the evaporating gases in tank 10A drops too low, the second stage is unnecessary.

[0101] Conversely, it can be decided that charging of tank 10B will only begin after the evaporating gas flow has become more stable and colder when the evaporating gas production is relatively low, rather than starting charging of tank 10B when the cooling operation of tank 10A begins. In this case, it can be decided to directly use the gas reheater 14, in which case the first stage described above does not occur.

[0102] The cooling operation of tank 10A can therefore be fully or partially overlapped with the inflation operation of tank 10B. If the cooling operation of tank 10A is completed before the inflation operation of tank 10B is completed, the inflation operation of tank 10B can be completed using any conventional method, such as... Figure 6 As shown.

[0103] exist Figure 6 In this process, storage tank 10A is partially filled with liquid LNG after cooling. To continue purging tank 10B, an injection pump 7 pumps LNG stream 30 into the liquid phase 23 stored at the bottom of tank 10A and delivers it, for example, via injection manifold 3 to vaporization unit 15. Vaporization unit 15 then generates vaporized natural gas stream 29 at a temperature of approximately 20°C, which is delivered to storage tank 10B to complete the purging operation.

[0104] The method described above for simultaneously performing the cooling operation of storage tank 10A and the gas filling operation of storage tank 10B can be used to improve gas testing procedures in liquefied natural gas carriers or any other LNG storage facilities. The following references... Figure 7 Such a procedure is described.

[0105] Figure 7 This is a timing diagram illustrating a series of operations that can be used for gas testing in a liquefied natural gas (LNG) carrier having four storage tanks of similar capacity arranged sequentially along the length of the vessel. Tank A is located at the stern of the vessel, and Tank D is located at the bow. The x-axis represents time in hours.

[0106] The operations specified by reference numerals 101 to 118 in the attached drawings are as follows:

[0107] 101: Inflation of tank A

[0108] Cooling of tank A (102)

[0109] 103: Partial inflation of tank B

[0110] 104: Partial filling of tank A

[0111] 105: Inflate (fill) tank B.

[0112] 106: Cooling of tank B

[0113] 107: Activation of the free-flow combustion unit (GCU)

[0114] 108: Activation of Low-Load Compressor (LDC)

[0115] 109: Inflate (fill) tank C.

[0116] 111: Final activation of the combustion unit

[0117] 112: Transferring the liquid phase from tank A to tank B (pump test)

[0118] 113: Cooling of tank C

[0119] 114: Inflate (fill) tank D.

[0120] 115: Transfer the liquid phase from tank B to tank C

[0121] 116: Cooling of tank D

[0122] 117: Transfer the liquid phase from tank C to tank D

[0123] 118: Transfer the liquid phase from tank D to tank A.

[0124] Steps 101 through 104 are performed in conjunction with an external source of LNG, namely an onshore terminal or refueling vessel connected to the LNG carrier. Steps 105 through 118 can be performed at sea, thus avoiding the cost of leasing an onshore terminal.

[0125] Figure 7 Box 100 indicates that the cooling operation of one tank can partially or completely overlap with the filling operation of the next tank, except for the cooling of the last tank. The evaporated gas produced by cooling can then be used for filling using the method described above. As a result, the total amount of evaporated gas produced in gas tests using this procedure is significantly reduced compared to conventional synchronous procedures.

[0126] This reduction in evaporative gas volume is easier to manage, whether through reliquefaction, combustion, return to the terminal, or release into the atmosphere, and is therefore beneficial in all cases. This benefit can be reduced operating costs and / or environmental benefits (reduced emissions).

[0127] Gas testing can be performed in tanks on one or more ships. In cases involving multiple ships, these ships need to be interconnected to allow for fluid exchange during the gas testing procedure. Therefore, while operations performed using a single ship's cargo handling system have been described above, it is understood that these operations can also be performed using cargo handling systems of two or more ships connected to each other. In this case, a manifold, such as a gasification manifold, can be understood as a combination of gasification manifolds from different interconnected ships.

[0128] refer to Figure 8 A cross-sectional view of the liquefied natural gas carrier 70 shows a sealed and insulated tank 71 with an integral prismatic shape installed in the ship's twin hulls 72. The walls of the tank 71 have: a primary sealing barrier intended to contact the LNG contained in the tank; a secondary sealing barrier disposed between the primary sealing barrier and the twin hulls 72; and two insulating barriers disposed between the primary sealing barrier and the secondary sealing barrier and between the secondary sealing barrier and the twin hulls 72, respectively.

[0129] In a known manner, the loading / unloading pipeline 73, which is arranged on the upper deck of the ship, can be connected to a marine or port terminal using appropriate connectors to transfer LNG cargo to or from tank 71.

[0130] Figure 8 An exemplary offshore terminal is shown, including a loading / unloading point 75, a subsea pipeline 76, and an onshore facility 77. The loading / unloading point 75 is a static offshore facility including a movable arm 74 and a column 78 holding the movable arm 74. The movable arm 74 carries a bundle of insulated hoses 79 that can be connected to a loading / unloading pipeline 73. The directional and movable arm 74 is suitable for LNG carriers of all sizes. A connecting line (not shown) extends within the column 78. The loading / unloading point 75 allows the LNG carrier vessel 70 to load and unload onto or from the onshore facility 77. The facility has LNG storage tanks 80 and a connecting line 81 connected to the loading / unloading point 75 via the subsea pipeline 76. The subsea pipeline 76 enables the LNG to be transferred over long distances, such as 5 km, between the loading / unloading point 75 and the onshore facility 77, allowing the LNG carrier vessel 70 to be located away from the coast during loading and unloading operations.

[0131] To generate the pressure required to transfer the liquefied gas, pumps carried on board the ship 70 and / or installed at the shore facility 77 and / or installed at the loading / unloading point 75 are used.

[0132] Although the present invention has been described in conjunction with several specific embodiments, it is obvious that it is by no means limited thereto. The present invention includes all technical equivalents of the described means and combinations thereof that fall within the scope of the present invention.

[0133] The use of the verbs "comprise" or "include," when referring to related terms, does not exclude the presence of other elements or steps besides those mentioned in the claims.

[0134] In the claims, the reference numerals in parentheses should not be construed as constituting a limitation on the claims.

Claims

1. A method for filling storage tanks in a liquefied gas storage facility located on a floating structure, the method comprising: The liquefied gas storage facility is brought into a ready state, the liquefied gas storage facility including multiple storage tanks (10A-10C) and at least one manifold (4, 2), the at least one manifold being connected in parallel to the top portion of each of the storage tanks. The first storage tank (10A) in the ready state is filled with gaseous liquefied gas (21), the temperature of the gaseous liquefied gas in the first storage tank being higher than the liquid-gas equilibrium temperature of the liquefied gas. The second storage tank (10B) in the ready state is filled with inert gas (22). The third storage tank (10C) in the ready state is partially or completely filled with liquid liquefied gas. The liquid-phase liquefied gas stream (25) is pumped into the third storage tank (10C). The liquid-phase liquefied gas stream (25) is delivered to the first storage tank via a jet manifold (3), which is connected in parallel to each of the storage tanks (10A-10C). The liquid-phase liquefied gas stream (25) is injected into the first storage tank (10A) to cool the first storage tank and to partially or completely vaporize the liquid-phase liquefied gas in the first storage tank. When the liquid-phase liquefied gas stream (25) is injected into the first storage tank (10A), a gaseous liquefied gas stream (26, 126) generated by the vaporization of the liquid-phase liquefied gas is conveyed from the top portion of the first storage tank to the top portion of the second storage tank (10B) via at least one manifold (4, 2) connected to the top portion of each storage tank, wherein the density of the gaseous liquefied gas (21) is lower than the density of the inert gas (22); and An inert gas flow (27) is released from the bottom portion of the second storage tank (10B) under the pressure of the gaseous liquefied gas flow, such that the gaseous liquefied gas (21) replaces the inert gas (22) at least in the top portion of the second storage tank (10B).

2. The inflation method according to claim 1, wherein, The at least one manifold is a maintenance manifold (4) which is connected in parallel to the top portion of each of the storage tanks via a corresponding first isolation valve (11) to transfer the gaseous liquefied gas stream (26, 126) from the top portion of the first storage tank to the maintenance manifold (4) via the first isolation valve (11) associated with the first storage tank (10A), and / or to transfer the gaseous liquefied gas stream (26, 126) from the maintenance manifold (4) to the top portion of the second storage tank (10B) via the first isolation valve (11) associated with the second storage tank.

3. The inflation method according to claim 2, wherein, The at least one manifold also includes a vaporization manifold (2), which is insulated and is connected in parallel to the top portion of each of the storage tanks via a corresponding second isolation valve (12). The vaporization manifold (2) is connected in series with the maintenance manifold (4) to sequentially deliver the vapor-phase liquefied gas stream (26) through the first isolation valve (11) associated with the first storage tank (10A), the maintenance manifold (4), the vaporization manifold (2), and the second isolation valve (12) associated with the second storage tank (10B), or to sequentially deliver the vapor-phase liquefied gas stream (26) through the second isolation valve (12) associated with the first storage tank, the vaporization manifold (2), the maintenance manifold (4), and the first isolation valve (11) associated with the second storage tank.

4. The inflation method according to any one of claims 1 to 3, wherein, The gaseous liquefied gas streams (26, 126) flow from the top portion of the first storage tank (10A) to the top portion of the second storage tank (10B) by natural convection.

5. The inflation method according to claim 3, wherein, The liquefied gas storage facility also includes a gas reheating device (14) having an inlet connected to one of the maintenance manifold (4) and the vaporization manifold (2) and an outlet connected to the other of the maintenance manifold (4) and the vaporization manifold (2), which also conveys the gaseous liquefied gas streams (26, 28) through the gas reheating device to reheat the gaseous liquefied gas streams (26, 28) before they reach the top portion of the second storage tank (10B).

6. The inflation method according to claim 3, wherein, The liquefied gas storage facility also includes a gas reheating device (14) having an inlet connected to one of the maintenance manifold (4) and the vaporization manifold (2) and an outlet connected to the other of the maintenance manifold (4) and the vaporization manifold (2). During the first flow phase, the gaseous liquefied gas stream (26) flows from the top portion of the first storage tank to the top portion of the second storage tank via natural convection. During the second flow phase, before the gaseous liquefied gas streams (26, 28) reach the top portion of the second storage tank, the gaseous liquefied gas streams (26, 28) are also passed through the gas reheating device (14) to reheat the gaseous liquefied gas streams (26, 28).

7. The inflation method according to claim 6, wherein, The inflation method further includes the following steps: The temperature of the gaseous liquefied gas exiting the first storage tank (10A) during the first flow phase is monitored; and When the temperature of the gaseous liquefied gas meets a predetermined standard, the gaseous liquefied gas flow (26) is switched to the gas reheating device (14).

8. The inflation method according to any one of claims 1 to 3, wherein, The liquid-phase liquefied gas stream is injected into the first storage tank through the injection device (5).

9. The inflation method according to any one of claims 1 to 3, wherein, The liquefied gas storage facility includes a liquid manifold (1) and a mast riser (13) connected to the liquid manifold (1), the liquid manifold being connected in parallel to the bottom portion of each of the storage tanks (10A-10C), and wherein an inert gas flow (27) exiting the second storage tank (10B) is delivered to the mast riser (13) via the liquid manifold (1).

10. A method for conducting gas testing in a liquefied gas storage facility located on a floating structure, the method comprising: The second storage tank is inflated using the inflation method according to any one of claims 1 to 3 (103, 105), and, after the second storage tank has been inflated, A liquid-phase liquefied gas stream (106) is injected into the second storage tank to cool the second storage tank.

11. A liquefied gas storage facility, the liquefied gas storage facility being supported on a floating structure, and the liquefied gas storage facility comprising: Multiple storage tanks (10A-10C). Maintenance manifold (4), which is connected in parallel to the top portion of each of the storage tanks via a corresponding first isolation valve (11); A vaporization manifold (2) is connected in parallel to the top portion of each of the storage tanks via a corresponding second isolation valve (12), and the vaporization manifold is insulated. A liquid manifold (1) is connected in parallel to the bottom portion of each of the storage tanks, and the liquid manifold is insulated; as well as Mast riser (13), which is connected to the liquid manifold; Each of the storage tanks (10A-10C) includes a filling line (9) and a vaporization line (6), the filling line (9) being connected to the liquid manifold (1), the vaporization line (6) leading to the top portion of the storage tank, and the vaporization line (6) being connected in parallel to the maintenance manifold (4) via a first isolation valve (11) associated with the storage tank, and the vaporization line (6) being connected in parallel to the vaporization manifold (2) via a second isolation valve (12) associated with the storage tank. The first isolation valve (11) can be switched to selectively connect the maintenance manifold (4) to the top portion of the first storage tank (10A) in the storage tank so that a gaseous liquefied gas flow (26) is transmitted from the first storage tank (10A) to the maintenance manifold (4) through the first isolation valve (11) associated with the first storage tank (10A).

12. The liquefied gas storage facility according to claim 11, wherein, The vaporization manifold (2) is connected in series with the maintenance manifold (4), and the second isolation valve (12) can be switched to selectively connect the vaporization manifold (2) to the top portion of the second storage tank (10B) in the storage tank, so that the vapor-phase liquefied gas flow (26) is delivered from the first storage tank sequentially through the first isolation valve (11) associated with the first storage tank, the maintenance manifold (4), the vaporization manifold (2) and the second isolation valve (12) associated with the second storage tank to the second storage tank.

13. The liquefied gas storage facility according to claim 11, further comprising an injection manifold (3) and an injection device (5), the injection manifold (3) being connected in parallel to each of the storage tanks, the injection device (5) being disposed in the top portion of each of the storage tanks and connected to the injection manifold (3).

14. The liquefied gas storage facility according to claim 11 or 12, wherein, The floating structure is a vessel (70) used for liquefied gases.

15. The liquefied gas storage facility according to claim 13, wherein, The floating structure is a vessel (70) used for liquefied gases.

16. A testing system for performing gas testing, the testing system comprising: The liquefied gas storage facility according to claim 15; Insulated pipes (73, 79, 76, 81) are arranged to connect the liquid manifold (1) or the jet manifold (3) to the shore terminal (77); and a pump for driving liquid-phase liquefied gas from the shore terminal through the insulated pipes to the liquid manifold (1) or the jet manifold (3).

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