SYSTEM FOR TRANSFERRING FLUID AND FLUID TRANSFER METHOD

Abstract

A system for transferring a fluid includes a transfer line connecting a storage tank and an LNG carrier, a loading arm provided on the transfer line, an emergency shutoff device configured to shut off the transfer line, a bypass line connecting the transfer line and the storage tank, and a bypass valve provided in the bypass line. The storage tank includes a fluid reception pipe configured to receive the fluid from the outside and a BOG pipe configured to discharge a boil-off gas of the fluid generated in the storage tank to the outside, and the bypass line is connected to at least one of the fluid reception pipe or the BOG pipe.

Claims

1. A system for transferring a fluid being a gas at room temperature and liquefied by cooling, the system comprising: a storage tank configured to store the fluid; a transfer line connecting the storage tank and an LNG carrier; a loading arm provided on the transfer line; an emergency shutoff device provided in the loading arm and configured to shut off the transfer line; a bypass line connecting a branch portion provided upstream of the loading arm in the transfer line and the storage tank; and a bypass valve provided in the bypass line and in a closed state during transfer of the fluid, wherein the storage tank includes a fluid reception pipe configured to receive the fluid from the outside and a BOG pipe configured to discharge a boil-off gas of the fluid generated in the storage tank to the outside, and the bypass line is connected to at least one of the fluid reception pipe or the BOG pipe.

2. The transfer system according to claim 1, further comprising: a control device configured to control the bypass valve, wherein the control device is configured to open the bypass valve from a closed state in a case where the emergency shutoff device is activated.

3. The system according to claim 1, further comprising: a plurality of the storage tanks; a plurality of the bypass lines connected to the plurality of storage tanks; and a plurality of the transfer lines, wherein the plurality of transfer lines are connected to one another, and the control device is configured to open the bypass valve of any one of the plurality of bypass lines from a closed state in a case where the emergency shutoff device is activated.

4. The system according to claim 1, further comprising: a plurality of the transfer lines, wherein the control device is configured to open the bypass valve of the bypass line from a closed state in a case where the emergency shutoff device corresponding to any one of the plurality of transfer lines is activated.

5. The system according to claim 1, wherein the branch portion provided in the transfer line is located onshore, and the loading arm is located offshore.

6. The system according to claim 1, wherein at least one pressure inside the fluid reception pipe or inside the BOG pipe to which the bypass line is connected is the same as a pressure of a gas phase in the storage tank.

7. A fluid transfer method by a system for transferring a fluid being a gas at room temperature and liquefied by cooling, the system including: a storage tank configured to store the fluid; a transfer line connecting the storage tank and an LNG carrier to transfer the fluid to the LNG carrier; a loading arm provided on the transfer line; an emergency shutoff device provided in the loading arm and configured to shut off the transfer line; a bypass line connecting a branch portion provided upstream of the loading arm in the transfer line and the storage tank; and a bypass valve provided in the bypass line and in a closed state during transfer of the fluid, the storage tank including a fluid reception pipe configured to receive the fluid from the outside and a BOG pipe configured to discharge a boil-off gas of the fluid generated in the storage tank to the outside, and the bypass line being connected to at least one of the fluid reception pipe or the BOG pipe, the fluid transfer method comprising opening the bypass valve in a case where the emergency shutoff device is activated.

8. The fluid transfer method according to claim 7, wherein the system further includes a plurality of the storage tanks, a plurality of the bypass lines connected to the plurality of storage tanks, and a plurality of the transfer lines, the plurality of transfer lines are connected to one another, and the bypass valve of any one of the plurality of bypass lines is opened from a closed state in a case where the emergency shutoff device is activated.

9. The fluid transfer method according to claim 7, wherein the system further includes a plurality of the transfer lines, and the bypass valve of the bypass line is opened from a closed state in a case where the emergency shutoff device corresponding to any one of the plurality of transfer lines is activated.

10. The system according to claim 2, further comprising: a plurality of the storage tanks; a plurality of the bypass lines connected to the plurality of storage tanks; and a plurality of the transfer lines, wherein the plurality of transfer lines are connected to one another, and the control device is configured to open the bypass valve of any one of the plurality of bypass lines from a closed state in a case where the emergency shutoff device is activated.

11. The system according to claim 2, further comprising: a plurality of the transfer lines, wherein the control device is configured to open the bypass valve of the bypass line from a closed state in a case where the emergency shutoff device corresponding to any one of the plurality of transfer lines is activated.

12. The system according to claim 2, wherein the branch portion provided in the transfer line is located onshore, and the loading arm is located offshore.

13. The system according to claim 3, wherein the branch portion provided in the transfer line is located onshore, and the loading arm is located offshore.

14. The system according to claim 4, wherein the branch portion provided in the transfer line is located onshore, and the loading arm is located offshore.

15. The system according to claim 2, wherein at least one pressure inside the fluid reception pipe or inside the BOG pipe to which the bypass line is connected is the same as a pressure of a gas phase in the storage tank.

16. The system according to claim 3, wherein at least one pressure inside the fluid reception pipe or inside the BOG pipe to which the bypass line is connected is the same as a pressure of a gas phase in the storage tank.

17. The system according to claim 4, wherein at least one pressure inside the fluid reception pipe or inside the BOG pipe to which the bypass line is connected is the same as a pressure of a gas phase in the storage tank.

18. The system according to claim 5, wherein at least one pressure inside the fluid reception pipe or inside the BOG pipe to which the bypass line is connected is the same as a pressure of a gas phase in the storage tank.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0028] FIG. 1 is an overall configuration diagram illustrating an overview of an LNG transfer system according to a first embodiment.

[0029] FIG. 2 is a diagram illustrating a first modification example of the LNG transfer system according to the first embodiment.

[0030] FIG. 3 is a diagram illustrating a second modification example of the LNG transfer system according to the first embodiment

[0031] FIG. 4 is an overall configuration diagram illustrating an overview of the LNG transfer system according to a second embodiment

DESCRIPTION OF EMBODIMENTS

[0032] Embodiments of the present invention are described below with reference to the drawings.

First Embodiment

[0033] FIG. 1 is an overall configuration diagram illustrating an overview of an LNG transfer system 1 according to a first embodiment.

[0034] The LNG transfer system 1 transfers LNG stored in a storage tank 3 onshore to an LNG carrier 5 offshore via a transfer line 4.

[0035] The storage tank 3 is provided with a fluid reception pipe 7 and a boil-off gas (BOG) pipe 9. The fluid reception pipe 7 passes through an upper wall 3a of the storage tank 3 and supplies the LNG from the outside to inside the storage tank 3. The fluid reception pipe 7 includes a vertical portion 7a extending in a vertical direction. Similarly, the BOG pipe 9 passes through the upper wall 3a of the storage tank 3 and discharges boil-off gas of the LNG generated in the storage tank 3 to the outside. The BOG pipe 9 includes a vertical portion 9a extending in the vertical direction. Lower ends of these vertical portions 7a, 9a are located in a gas phase 11a of LNG 11 stored in the storage tank 3.

[0036] The LNG from the outside is supplied to the fluid reception pipe 7. Such LNG is generated by liquefying natural gas in an LNG liquefaction system (not illustrated). An expansion valve 13 is provided in the fluid reception pipe 7. The LNG from the LNG liquefaction system expands by the expansion valve 13, is thus adjusted in temperature to approximately -162° C., and flows into the storage tank 3.

[0037] The boil-off gas discharged from the BOG pipe 9 is re-liquefied using a compressor and a cooler (not illustrated).

[0038] The transfer line 4 connects the storage tank 3 and the LNG carrier 5 onshore to transfer the LNG. In the following description, the storage tank 3 side of the transfer line 4 that supplies LNG is regarded as upstream, and the LNG carrier 5 side of the transfer line 4 that receives LNG is regarded as downstream.

[0039] In the transfer line 4, a pump (not illustrated) that transfers the LNG is provided in the vicinity of the storage tank 3. Further, a check valve 23 and a flow regulating valve 25 are provided in this order downstream of the pump in the transfer line 4.

[0040] Further, the transfer line 4 onshore is provided with a bypass branch portion 31. A bypass line 33 connects the bypass branch portion 31 of the transfer line 4 and the fluid reception pipe 7 of the storage tank 3. A connecting portion 33a of the bypass line 33 connecting to the fluid reception pipe 7 is downstream of the expansion valve 13. The bypass line 33 includes a bypass valve 35 and, during normal transfer, the bypass valve 35 shuts off the inflow of the LNG from the transfer line 4 to the bypass line 33.

[0041] Further, the transfer line 4 offshore is provided with a loading arm 37 for fluid cargo handling. The loading arm 37 is provided with an emergency shutoff device 43 that shuts off the transfer line 4 downstream of an arm body 41 thereof. The emergency shutoff device 43 includes two emergency shutoff valves 51, 52 and an emergency release coupler 53 interposed therebetween.

[0042] Further, the loading arm 37 includes an emergency shutdown (ESD) system 55 that actuates the emergency shutoff device 43. The ESD system 55 operates in an emergency in which an angle abnormality of the arm body 41 occurs, and transmits an emergency shutoff signal to the emergency shutoff device 43. As a result, the emergency shutoff device 43 that receives the emergency shutoff signal is activated. Then, in the emergency shutoff device 43, the two emergency shutoff valves 51, 52 are closed, and the emergency release coupler 53 is subsequently opened. The opening of the emergency release coupler 53 is performed by, for example, control of hydraulic pressure.

[0043] Note that the emergency shutoff device 43 is not limited to the configuration illustrated herein. Further, the emergency shutoff device 43 provided in the loading arm 37 need not necessarily be integrally provided with the arm body 41. The emergency shutoff device 43 is provided in at least the transfer line 4, and need only shut off the flow of the LNG in the transfer line 4 in an emergency.

[0044] Further, a shutoff valve 57 that shuts off the transfer line 4 is provided on the transfer line 4 offshore, upstream of the loading arm 37. The shutoff valve 57 closes when the emergency shutoff valve 51 fails and shuts off the flow of the LNG in the transfer line 4.

[0045] The LNG carrier 5 includes a carrier-side tank (not illustrated). The carrier-side tank is filled with the LNG from the storage tank 3. Further, a carrier-side pipe 61 extending from the carrier-side tank is connected to one of the emergency shutoff valves 51, 52, namely, emergency shutoff valve 52 at an upstream end of the carrier-side pipe 61, and constitutes a portion of the transfer line 4. The LNG carrier 5 transfers the LNG received from the storage tank 3 to another location.

[0046] Note that, in this embodiment, an example is illustrated in which the storage tank 3 is provided onshore, but the storage tank 3 may be provided offshore. The storage tank 3 can be provided on an offshore floating storage unit (FSU), a floating LNG (FLNG), or the like. Further, in the LNG transfer system 1, all components including the transfer line 4 may be provided offshore. When the LNG is transferred from the FLNG to the LNG carrier 5, a loading hose is used instead of the loading arm.

[0047] Further, the LNG transfer system 1 is provided with a control device 63. The control device 63 receives an emergency shutoff signal from the ESD system 55, which signals the activation of the emergency shutoff device 43 in an emergency, and controls the opening of the bypass valve 35. Note that the emergency shutoff signal received by the control device 63 is not limited to that transmitted from the ESD system 55. As long as the emergency shutoff signal is a signal that signals the activation of the emergency shutoff device 43, the signal may be transmitted from another device. Alternatively, instead of reception of the emergency shutoff signal, an operator of the LNG transfer system 1 may perform an input operation in the control device 63 for controlling the bypass valve 35.

[0048] During the LNG transfer operation, the LNG 11 in the storage tank 3 is transferred toward the LNG carrier 5 offshore by the pump of the transfer line 4. At this time, the bypass valve 35 of the bypass line 33 is in the closed state, and thus the LNG does not flow through the bypass line 33.

[0049] When an emergency occurs during the LNG transfer operation, the ESD system 55 transmits an emergency shutoff signal to the emergency shutoff device 43 and simultaneously transmits an emergency shutoff signal to the control device 63. Then, in the emergency shutoff device 43 receiving the emergency shutoff signal, the emergency shutoff valves 51, 52 are closed and the emergency release coupler 53 is opened. Further, the control device 63 receiving the emergency shutoff signal controls the bypass valve 35 from the closed state to the open state.

[0050] In this case, the flow of the LNG in the transfer direction in the transfer line 4 is shut off by the emergency shutoff valve 51. On the other hand, a portion of the LNG 11 in the transfer line 4 flows from the bypass branch portion 31 to the bypass line 33. Furthermore, the LNG flowing into the bypass line 33 flows through the fluid reception pipe 7 and into the storage tank 3. With such a bypass line 33, a pressure surge generated by sudden shutoff of the flow of the LNG in the transfer line 4 is mitigated. Note that the backflow of the LNG from the emergency shutoff valve 51 to the storage tank 3 via the transfer line 4 is stopped by the check valve 23.

[0051] Further, in the connecting portion 33a of the bypass line 33, a pressure in the fluid reception pipe 7 is substantially the same as a pressure of the gas phase 11a of the LNG 11 stored in the storage tank 3. Thus, the LNG of the bypass line 33 flows stably into the storage tank 3 without being affected by the pressure of the LNG supplied from the outside to the fluid reception pipe 7.

[0052] FIG. 2 is a diagram illustrating a first modification example of the LNG transfer system 1 according to the first embodiment. FIG. 3 is a diagram illustrating a second modification example of the LNG transfer system 1 according to the first embodiment. In FIGS. 2 and 3, components similar to those of the LNG transfer system 1 illustrated in FIG. 1 are denoted by the same reference signs. However, for convenience of description, auxiliary signs A to D are added to the numbers in the reference signs for some components. Further, the first and second modification examples of the LNG transfer system 1 are similar to those of the first embodiment described above except for the matters specifically mentioned below.

[0053] In the first modification example of the LNG transfer system 1, the storage tank 3, the bypass line 33 connected to the storage tank 3, and the transfer line 4 are each added. In the first modification example, in addition to a first transfer line 4A, which corresponds to the transfer line 4 in the first embodiment described above, a second transfer line 4B is provided. The second transfer line 4B has a configuration similar to that of the first transfer line 4A.

[0054] As illustrated in FIG. 2, a transfer line branch portion 71 (hereinafter referred to as “branch portion 71”) is provided in the first transfer line 4A onshore and downstream of the bypass branch portion 31. The second transfer line 4B branches from the first transfer line 4A at the branch portion 71.

[0055] Further, downstream ends of a third transfer line 4C and a fourth transfer line 4D are each connected to the second transfer line 4B branching from the branch portion 71. Upstream ends of the third transfer line 4C and the fourth transfer line 4D are respectively connected to storage tanks 3C, 3D independent of each other. Further, bypass branch portions 31C, 31D are respectively provided upstream of the third transfer line 4C and the fourth transfer line 4D, and each of the bypass branch portions 31 is connected to the corresponding storage tank 3 via a corresponding one of bypass lines 33C, 33D.

[0056] Note that, in addition to the first transfer line 4A and the second transfer line 4B, an additional transfer line constituting the downstream side may be added. Further, in addition to the third transfer line 4C and the fourth transfer line 4D, an additional transfer line constituting the upstream side as well as equipment for supplying LNG thereto may be added.

[0057] In the first modification example of the LNG transfer system 1, during an LNG transfer operation, the LNG is transferred from any one of the three storage tanks 3, 3C, 3D via the first transfer line 4A or the second transfer line 4B. At this time, the bypass valves 35, 35C, 35D of the bypass lines 33, 33C, 33D are in a closed state, and thus the LNG does not flow through the bypass lines 33, 33C, 33D.

[0058] For example, when an emergency occurs during the LNG transfer operation using the second transfer line 4B and the third transfer line 4C, emergency shutoff valves 51B, 52B in the second transfer line 4B are closed, and an emergency release coupler 53B is released. Further, the control device 63 receiving the emergency shutoff signal controls the bypass valves 35, 35C, 35D in all bypass lines 33, 33C, 33D such that the bypass valves 35, 35C, 35D is set from the closed state to the open state.

[0059] In this case, the flow of the LNG in the transfer direction in the second transfer line 4B is shut off by the emergency shutoff valve 51B of the second transfer line 4B. On the other hand, a portion of the LNG 11 in the second transfer line 4B flows through the bypass lines 33, 33C, 33D and into at least one of the storage tanks 3, 3C, 3D that had supplied the LNG. Accordingly, pressure surges generated in the plurality of transfer lines connected to the plurality of storage tanks can be mitigated.

[0060] In the second modification example of the LNG transfer system 1, as illustrated in FIG. 3, the third transfer line 4C and fourth transfer line 4D as well as the equipment supplying the LNG thereto in the first modification example are omitted. That is, the LNG transfer system 1 can include the plurality of transfer lines 4A, 4B connected to one storage tank 3. In this case as well, a portion of the liquefied fluid in the transfer line 4A or the transfer line 4B shut off flows through the bypass line 33 and into the storage tank. Accordingly, pressure surges generated in the plurality of transfer lines connected to one storage tank 3 can be mitigated.

Second Embodiment

[0061] FIG. 4 is an overall configuration diagram illustrating an overview of the LNG transfer system 1 according to a second embodiment. In FIG. 4, components similar to those of the LNG transfer system 1 illustrated in FIG. 1 are denoted by the same reference signs. Further, the LNG transfer system 1 according to the second embodiment is similar to that of the first embodiment or the modification examples thereof described above except for the matters specifically mentioned below.

[0062] In the LNG transfer system 1 according to the second embodiment, the bypass line 33 is connected to the bypass branch portion 31 of the transfer line 4 and the BOG pipe 9 of the storage tank 3.

[0063] When an emergency occurs during an LNG transfer operation, the LNG flowing into the bypass line 33 flows through the BOG pipe 9 and into the storage tank 3. By such utilization of the bypass line 33, a pressure surge generated by sudden shutoff of the LNG flow in the transfer line 4 is mitigated.

[0064] Further, in the connecting portion 33b of the BOG pipe 9 connecting to the bypass line 33, the pressure in the pipe is substantially the same as the pressure of the gas phase 11a of the LNG 11 stored in the storage tank 3. As a result, the LNG of the bypass line 33 flows stably into the storage tank 3 without being affected by the pressure of the boil-off gas discharged from the BOG pipe 9 to the outside.

[0065] Note that, in the LNG transfer system 1 according to the second embodiment as well, a plurality of the storage tanks 3 and a plurality of the transfer lines 4 connected thereto can be provided similarly to the modification examples of the LNG transfer system 1 according to the first embodiment. Further, the bypass line 33 may branch in the middle, and thus be further connected to the fluid reception pipe 7 in the same manner as in the first embodiment. In this case, whether the LNG flowing through the bypass line 33 is to flow into the fluid reception pipe 7 or the BOG pipe 9 may be selected by an opening/closing operation of valves (not illustrated) respectively provided on the fluid reception pipe 7 side and the BOG pipe 9 side.

[0066] Although the present invention has been described using specific embodiments, these embodiments are merely illustrative, and the present invention is not limited by these embodiments. The components of the system for transferring a fluid and the fluid transfer method according to the present invention described above in the embodiments are not all necessary and can be appropriately selected by at least a person skilled in the art without departing from the scope of the present invention.

[0067] The system for transferring a fluid and the fluid transfer method according to the present invention are applicable to not only LNG, but any fluid that vaporizes at room temperature. For example, liquefied petroleum gas (LPG) may be used as the fluid that vaporizes at room temperature.

REFERENCE SIGNS LIST

[0068] 1 LNG transfer system [0069] 3 Storage tank [0070] 4 Transfer line [0071] 4A First transfer line [0072] 4B Second transfer line [0073] 4C Third transfer line [0074] 4D Fourth transfer line [0075] 5 LNG carrier [0076] 7 Fluid reception pipe [0077] 9 BOG pipe [0078] 11a Gas phase [0079] 13 Expansion valve [0080] 23 Check valve [0081] 25 Flow regulating valve [0082] 31 Bypass branch portion [0083] 33 Bypass line [0084] 35 Bypass valve [0085] 37 Loading arm [0086] 41 Arm body [0087] 43 Emergency shutoff device [0088] 51 Emergency shutoff valve [0089] 52 Emergency shutoff valve [0090] 53 Emergency release coupler [0091] 55 ESD system [0092] 57 Shutoff valve [0093] 61 Carrier-side pipe [0094] 63 Control device [0095] 71 Transfer line branch portion