Floating body

Abstract

The floating body is provided with: a floating body main body; a liquefied gas tank which is provided to the floating body main body and in which liquefied gas is stored; a combustion machine provided in the floating body main body and driven by liquefied gas; the liquefied gas pipeline is connected with the liquefied gas tank and the combustion machine; a gas-liquid separation tank into which the liquefied gas from the liquefied gas line is introduced together with the purge gas; the recovery tank is arranged below the gas-liquid separation tank and allows the liquefied gas stored in the gas-liquid separation tank to flow down; a pressure equalizing pipe which enables the gas phase area of the recovery tank and the gas phase area of the liquefied gas pipeline to be communicated with each other; and a return pipe capable of feeding the liquefied gas from the recovery tank to the liquefied gas line.

Description

Technical Field

[0001] The invention relates to a floating body.

[0002] This application claims priority based on patent application No. 2022-115203 filed in Japan on July 20, 2022, and the contents are incorporated herein by reference. Background Art

[0003] Patent Document 1 discloses a ship (floating body) that sails on the ocean using liquefied gas as fuel. The floating body includes a storage tank that stores liquefied gas, an engine that uses the liquefied gas as fuel, and a fuel supply line that supplies the liquefied gas in the storage tank to the engine.

[0004] Previous technical literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application No. 2021-532016 Summary of the invention

[0007] Technical issues to be solved by the invention

[0008] However, in an engine using liquefied gas as fuel as described in Patent Document 1, when the engine stops running for a long time or when the supplied fuel is switched, it is necessary to purge the liquefied gas remaining in the engine and the piping and discharge it. The liquefied gas discharged in this way is recovered together with the purge gas by the gas-liquid separator tank and then separated into gas and liquid. Then, the liquefied gas after gas-liquid separation evaporates in the gas-liquid separator tank and is discharged into the atmosphere, or is often discarded after being detoxified by a detoxification device, which results in energy loss.

[0009] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a floating body capable of reducing energy loss.

[0010] Means for solving technical problems

[0011] In order to solve the above-mentioned problems, the float involved in the present invention comprises: a float body; a liquefied gas tank, which is arranged on the float body and stores liquefied gas; a combustion machine, which is arranged on the float body and driven by liquefied gas; a liquefied gas pipeline, which connects the liquefied gas tank and the combustion machine; a gas-liquid separation tank, into which the liquefied gas and the purge gas of the liquefied gas pipeline are introduced together; a recovery tank, which is arranged below the gas-liquid separation tank, for the liquefied gas stored in the gas-liquid separation tank to flow down; a pressure equalizing pipe, which connects the gas phase area of ​​the recovery tank with the gas phase area of ​​the liquefied gas pipeline; and a reflux pipe, which can deliver liquefied gas from the recovery tank to the liquefied gas pipeline.

[0012] Effects of the Invention

[0013] According to the floating body of the present invention, energy loss can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a side view of the ship according to the first embodiment of the present invention.

[0015] Figure 2 It is a diagram showing a piping system for performing fuel supply and fuel purging of a ship according to the first embodiment of the present invention.

[0016] Figure 3 This is a flowchart showing a procedure for returning liquefied gas to a liquefied gas pipeline according to the first embodiment of the present invention.

[0017] Figure 4 It is a diagram showing a piping system for performing fuel supply and fuel purging of a ship according to a second embodiment of the present invention.

[0018] Figure 5 It is a diagram showing a piping system for performing fuel supply and fuel purging of a ship according to a third embodiment of the present invention.

[0019] Figure 6 It is a diagram showing a piping system for performing fuel supply and fuel purging of a ship according to a fourth embodiment of the present invention.

[0020] Figure 7 This is a flowchart showing an example of a liquefied gas return step to a liquefied gas pipeline according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0021] <First embodiment>

[0022] (Ship)

[0023] Below, reference Figures 1 to 3 , a floating body according to a first embodiment of the present invention will be described.

[0024] The floating body of this embodiment is a ship 1 that travels on the ocean by using heat energy generated by burning liquefied gas. In this embodiment, liquefied ammonia is used as the liquefied gas as the fuel of the combustion machine 9. In addition to liquefied ammonia, for example, LNG (Liquefied Natural Gas) or LPG (Liquefied Petroleum Gas) can also be used as the liquefied gas as the fuel of the combustion machine 9.

[0025] like Figure 1As shown, the ship (floating body) 1 of this embodiment includes a hull (floating body body) 2, a superstructure 4, a liquefied gas tank 8, a combustion device 9, and a piping system 10. The ship type of the ship 1 is not limited to a specific one. Examples of the ship type of the ship 1 include a liquefied gas tanker, a ferry, a RORO ship, a car tanker, a passenger ship, and the like.

[0026] (Hull)

[0027] The hull 2 ​​has a pair of sidewalls 5 and a bottom 6 constituting its outer shell. The sidewalls 5 include a pair of sidewall outer plates forming the port and starboard sides, respectively. The bottom 6 includes a bottom outer plate connecting the sidewalls 5. The outer shell of the hull 2 ​​is U-shaped in a cross section perpendicular to the bow and stern direction by the pair of sidewalls 5 and the bottom 6.

[0028] The hull 2 ​​also includes an upper deck 7 which is a full-length deck disposed at the uppermost layer. The upper structure 4 is formed on the upper deck 7. A living area and the like are provided in the upper structure 4. In the ship 1 of the present embodiment, for example, a cargo hold (not shown) for carrying cargo is provided at a position closer to the bow 3a side in the bow and stern direction than the upper structure 4.

[0029] (Liquefied gas tank)

[0030] The liquefied gas tank 8 is provided on the hull 2 ​​and stores liquefied gas as fuel for the combustion machine 9 described later. The liquefied gas tank 8 illustrated in the present embodiment is provided on the upper deck 7 closer to the stern 3b side than the upper structure 4, but the configuration of the liquefied gas tank 8 is not limited to the upper deck 7 closer to the stern 3b side than the upper structure 4.

[0031] (Burning Machine)

[0032] The combustion machine 9 is a device that generates heat energy by being driven by the combustion of the liquefied gas supplied from the liquefied gas tank 8, and is provided in the hull 2. Examples of the combustion machine 9 include an internal combustion engine used in a main engine for sailing the ship 1, an internal combustion engine used in a generator for supplying power to the ship, and a boiler for generating steam as a working fluid.

[0033] (Piping system)

[0034] The piping system 10 supplies liquefied gas from the liquefied gas tank 8 to the combustion device 9 and purges the liquefied gas remaining in the combustion device 9. Figure 2 , the structure of the piping system 10 will be described.

[0035] like Figure 2As shown, the piping system 10 includes a liquefied gas pipeline 30, a purge gas supply device 40, a purge pipeline 50, a gas-liquid separation tank 11, an exhaust pipe 12, a first liquid level sensor 60, a recovery pipe 14, a recovery stop valve 15, a recovery tank 13, a second liquid level sensor 61, a pressure equalizing pipe 16, a pressure equalizing stop valve 17, a reflux pipe 18, a reflux stop valve 19, a reflux pump 20, a discharge pipe 21, and a discharge stop valve 22. Each structure of the piping system 10 is provided in a fuel adjustment chamber S provided in the hull 2. The fuel adjustment chamber S is set as an airtight structure, and the indoor ventilation is performed by a ventilator (not shown).

[0036] In addition, each structure of the piping system 10 does not need to be provided in the fuel adjustment chamber S.

[0037] (Liquefied gas pipeline)

[0038] The liquefied gas pipeline 30 connects the liquefied gas tank 8 and the combustion machine 9. A high pressure higher than the atmospheric pressure is maintained in the liquefied gas pipeline 30. In addition, a pressure higher than the saturated vapor pressure is maintained at the temperature of each position in the system of the liquefied gas pipeline 30. Therefore, the gas in the liquefied gas pipeline 30 can be maintained in a liquefied state. The liquefied gas pipeline 30 includes an introduction pipe 32, an introduction part 31, a supply pipe 33, a supply pump 35, a supply stop valve 36, a return pipe 34, a return stop valve 37, and a capture tank 38.

[0039] (Introduction tube)

[0040] The introduction pipe 32 is a pipe that connects the liquefied gas tank 8 and the introduction portion 31 so that they communicate with each other.

[0041] (Introduction section)

[0042] The introduction part 31 is a tank for introducing liquefied gas from the liquefied gas tank 8 through the introduction pipe 32. In addition, the introduction part 31 is also a storage tank for introducing the liquefied gas stored in the capture tank 38 by connecting to the return pipe 34. That is, the introduction part 31 is a mixing tank capable of temporarily storing the liquefied gas introduced from the liquefied gas tank 8 and the capture tank 38.

[0043] (Supply pipe)

[0044] The supply pipe 33 is a pipe for supplying the liquefied gas introduced into the introduction portion 31 to the combustion device 9. The supply pipe 33 is provided with a supply pump 35, a supply stop valve 36, a heat exchanger (not shown), and a pressure regulating valve (not shown).

[0045] (Supply pump)

[0046] The supply pump 35 pressurizes and delivers the liquefied gas from the introduction portion 31 toward the combustion device 9 .

[0047] (Supply stop valve)

[0048] The supply stop valve 36 is provided in the supply pipe 33 between the supply pump 35 and the combustion machine 9. That is, two supply stop valves 36 are arranged in the flow direction of the liquefied gas on the supply pipe 33 on the downstream side of the supply pump 35. The supply stop valve 36 is a so-called main fuel stop valve which is provided to open and close the supply pipe 33 and cut off the flow of the fluid in the supply pipe 33 by closing the supply pipe 33. Hereinafter, the supply stop valve 36 on the upstream side (liquefied gas tank 8 side) of the two supply stop valves 36 provided in the supply pipe 33 is referred to as the upstream side main fuel stop valve 36a, and the supply stop valve 36 on the downstream side (combustion machine 9 side) is referred to as the downstream side supply stop valve 36b.

[0049] (Return pipe)

[0050] The return pipe 34 is a pipe for returning the remaining liquefied gas that is not used as fuel in the combustion machine 9 to the introduction portion 31. A return stop valve 37, a capture tank 38, a heat exchanger (not shown), and a pressure / flow regulating valve (not shown) are provided in the middle of the return pipe 34.

[0051] (Return stop valve)

[0052] A plurality of return stop valves 37 are arranged in a row along the flow direction of the liquefied gas. In the present embodiment, a case where two return stop valves 37 are arranged in a row along the flow direction of the liquefied gas is shown as an example. The return stop valve 37 is also a so-called main fuel stop valve that is arranged to open and close the return pipe 34 and cut off the flow of the fluid in the return pipe 34 by closing the return pipe 34. Hereinafter, the return stop valve 37 on the upstream side (the combustion machine 9 side) of the two return stop valves 37 arranged in the return pipe 34 is referred to as the upstream side return stop valve 37a, and the return stop valve 37 on the downstream side (the liquefied gas tank 8 side) is referred to as the downstream side main fuel stop valve 37b.

[0053] (Catch tank)

[0054] The capture tank 38 is provided on the return pipe 34 which is closer to the liquefied gas tank 8 than the two return stop valves 37, that is, on the downstream side than the two return stop valves 37. The capture tank 38 temporarily stores the liquefied gas returned from the combustion machine 9. A liquid phase formed by the liquefied gas and a gas phase formed by gas after the liquefied gas is vaporized are formed in the capture tank 38. In the present embodiment, the liquefied gas returned from the combustion machine 9 is introduced into the liquid phase of the capture tank 38. And the liquefied gas stored in the liquid phase of the capture tank 38 is returned to the introduction part 31 via the return pipe 34. The internal pressure of the capture tank 38 is maintained at a high pressure of, for example, about 2.5 MPa.

[0055] The liquefied gas pipeline 30 is provided with a purge gas supply device 40 for supplying purge gas into the combustion machine 9 .

[0056] (Purge gas supply device)

[0057] The purge gas supply device 40 performs so-called purge in which the liquefied gas remaining in the combustion device 9 is replaced with the purge gas. The purge gas is, for example, an inert gas such as nitrogen. The purge gas supply device 40 includes a purge gas supply unit 41, a purge gas supply pipe 42, and a purge gas supply valve 43.

[0058] (Purge gas supply section)

[0059] The purge gas supply unit 41 can supply the purge gas to the purge gas supply pipe 42 .

[0060] (Purge gas supply pipe)

[0061] The purge gas supply pipe 42 connects the purge gas supply unit 41 and the liquefied gas pipeline 30. The purge gas supply pipe 42 is connected to the area P to be purged.

[0062] The purge target area P is an area between the upstream main fuel stop valve 36a of the supply pipe 33 and the downstream main fuel stop valve 37b of the return pipe 34 and on the side of the burner 9, including at least the burner 9 and the liquefied gas line 30. In the present embodiment, the purge gas supply pipe 42 is connected between the downstream supply stop valve 36b in the supply pipe 33 and the burner 9.

[0063] (Purge gas supply valve)

[0064] The purge gas supply valve 43 is provided on the purge gas supply pipe 42. The purge gas supply valve 43 is provided to be able to open and close the purge gas supply pipe 42. In normal times (when the combustion machine 9 is driven), the purge gas supply valve 43 closes the purge gas supply pipe 42 and cuts off the supply of the purge gas from the purge gas supply unit 41 to the purge target area P of the piping system 10.

[0065] When the ammonia operation of the combustion machine 9 is stopped, the purge gas supply valve 43 opens the purge gas supply pipe 42. At this time, the supply pipe 33 and the return pipe 34 are closed by the upstream main fuel stop valve 36a and the downstream main fuel stop valve 37b, and the flow of the liquefied gas between the liquefied gas tank 8 and the combustion machine 9 is cut off. That is, the supply of the liquefied gas from the liquefied gas tank 8 to the combustion machine 9 is stopped. In this state, if the purge gas supply valve 43 is operated to open the purge gas supply pipe 42, the purge gas is supplied from the purge gas supply unit 41 to the purge target area P. The purge gas supply device 40 replaces the liquefied gas in the purge target area P with the purge gas by supplying the purge gas to the purge target area P.

[0066] The liquefied gas is pushed out from the purge target area P to the purge line 50 by the purge gas supplied from the purge gas supply device 40 .

[0067] (Purge line)

[0068] The purge line 50 guides the liquefied gas and the purge gas pushed out from the purge target area P of the liquefied gas line 30 to the gas-liquid separator 11. The purge line 50 includes a supply side purge pipe 51, a supply side purge valve 52, a return side purge pipe 53, and a return side purge valve 54.

[0069] (Supply side purge pipe)

[0070] The supply-side purge pipe 51 connects the supply pipe 33 and the gas-liquid separator 11. The end of the supply-side purge pipe 51 on the supply pipe 33 side is connected to the area between the two supply stop valves 36 in the supply pipe 33. The supply-side purge pipe 51 is provided with a supply-side purge valve 52 capable of opening and closing the supply-side purge pipe 51.

[0071] (Supply side purge valve)

[0072] In normal times (when the combustion machine 9 is driven), the supply-side purge valve 52 closes the supply-side purge pipe 51 and prevents the liquefied gas from flowing from the supply pipe 33 into the supply-side purge pipe 51. On the other hand, when the purge gas is supplied by the purge gas supply device 40, the supply-side purge valve 52 opens the supply-side purge pipe 51. If the supply-side purge pipe 51 is opened, the liquefied gas and the purge gas squeezed out of the purge target area P by the purge gas flow into the supply-side purge pipe 51. Then, the liquefied gas and the purge gas flowing into the supply-side purge pipe 51 are guided to the gas-liquid separation tank 11. In addition, the supply-side purge valve 52 of the present embodiment, together with the two supply stop valves 36, constitute a so-called double shutoff and release valve.

[0073] In addition, a plurality of supply-side purge pipes 51 may be provided on the supply pipe 33 . In this case, at least one supply-side purge valve 52 is provided on each supply-side purge pipe 51 .

[0074] (Return side purge pipe)

[0075] The return side purge pipe 53 connects the return pipe 34 and the gas-liquid separator 11. In the present embodiment, three return side purge pipes 53 are provided. The end of one of the three return side purge pipes 53 on the return pipe 34 side is connected to the area between the two return stop valves 37 in the return pipe 34. The end of two of the three return side purge pipes 53 on the return pipe 34 side is connected to the area between the combustion machine 9 and the upstream return stop valve 37a in the return pipe 34. These three return side purge pipes 53 merge on the downstream side and are connected to the gas-liquid separator 11. A return side purge valve 54 capable of opening and closing the return side purge pipe 53 is provided on each return side purge pipe 53.

[0076] (Return side purge valve)

[0077] In normal times (when the combustion machine 9 is driven), the return-side purge valve 54 closes the return-side purge pipe 53 and prevents the liquefied gas from flowing from the return pipe 34 into the return-side purge pipe 53. On the other hand, when the purge gas is supplied by the purge gas supply device 40, the return-side purge valve 54 opens the return-side purge pipe 53. If the return-side purge pipe 53 is opened, the liquefied gas and the purge gas squeezed out of the purge target area P by the purge gas flow into the return-side purge pipe 53. Moreover, the liquefied gas and the purge gas flowing into the return-side purge pipe 53 are guided to the gas-liquid separation tank 11. In addition, the return-side purge valve 54 of the present embodiment, together with the two return stop valves 37, constitute a so-called double shutoff and release valve.

[0078] In addition, one, two, or four or more return-side purge pipes 53 may be provided on the return pipe 34, and the number of return-side purge pipes 53 may be appropriately changed. Regardless of the number of return-side purge pipes 53, at least one return-side purge valve 54 is provided on each return-side purge pipe 53.

[0079] The purge pipeline 50 connects the liquefied gas pipeline 30 and the gas-liquid separation tank 11 .

[0080] (Gas-liquid separation tank)

[0081] The liquefied gas in the liquefied gas line 30 is introduced into the gas-liquid separator 11 together with the purge gas. The liquefied gas (liquid) and the gas generated by evaporation of the liquefied gas and the gas (gas) such as the purge gas are separated into gas and liquid in the gas-liquid separator 11. The internal pressure of the gas-liquid separator 11 is maintained near the atmospheric pressure.

[0082] The liquid phase gas in the liquefied gas guided to the gas-liquid separation tank 11 through the purge line 50 is stored in the gas-liquid separation tank 11. The liquefied gas stored in the gas-liquid separation tank 11 flows to the recovery tank 13 provided below the gas-liquid separation tank 11 through the recovery pipe 14. Therefore, the storage amount of the liquefied gas in the gas-liquid separation tank 11 gradually decreases. In order to measure the storage amount of the liquefied gas in the gas-liquid separation tank 11, a first liquid level sensor 60 is provided in the gas-liquid separation tank 11.

[0083] On the other hand, the gas phase gas such as the purge gas guided to the gas-liquid separation tank 11 through the purge line 50 is discharged to the outside through the exhaust pipe 12 communicating with the gas-liquid separation tank 11 .

[0084] (Exhaust pipe)

[0085] The exhaust pipe 12 extends from the gas-liquid separation tank 11. The exhaust pipe 12 is connected to the gas phase in the gas-liquid separation tank 11. The end of the exhaust pipe 12 on the opposite side of the gas-liquid separation tank 11 can be opened to the atmosphere outside the ship 1, and can also be connected to a harm removal device (not shown) for removing harm from the gas phase generated by evaporation of the liquefied gas.

[0086] (First liquid level sensor)

[0087] The first liquid level sensor 60 detects the position of the liquid level of the liquefied gas in the gas-liquid separation tank 11. The first liquid level sensor 60 can adjust the flow rate of the liquefied gas guided from the gas-liquid separation tank 11 to the recovery tank 13 so that the storage amount of the liquefied gas in the gas-liquid separation tank 11 is maintained between a specified upper limit value and a specified lower limit value.

[0088] (Recovery tube)

[0089] The recovery pipe 14 guides the liquefied gas from the gas-liquid separation tank 11 to the recovery tank 13. The recovery pipe 14 is provided with a recovery stop valve 15 capable of opening and closing the recovery pipe 14.

[0090] (Recovery stop valve)

[0091] The recovery stop valve 15 can move the liquefied gas in the recovery pipe 14 by opening the recovery pipe 14, and cut off the movement of the liquefied gas in the recovery pipe 14 by closing the recovery pipe 14. Hereinafter, the state in which the recovery stop valve 15 closes the recovery pipe 14 is referred to as the closed state of the recovery stop valve 15, and the state in which the recovery stop valve 15 opens the recovery pipe 14 is referred to as the open state of the recovery stop valve 15.

[0092] (Recycling tank)

[0093] The recovery tank 13 recovers the liquefied gas stored in the gas-liquid separation tank 11. The recovery tank 13 has a volume that can store all the liquefied gas stored in the gas-liquid separation tank 11. For example, the volume of the recovery tank 13 is larger than the volume of the gas-liquid separation tank 11. Both the gas-liquid separation tank 11 and the liquefied gas pipeline 30 are pressurized, so the recovery tank 13 uses a pressure vessel with a wide pressure range. In addition, in the present embodiment, the recovery tank 13 is longitudinally arranged at a position opposite to the capture tank 38 in the horizontal direction.

[0094] In order to measure the storage amount of the liquefied gas tank 8 in the recovery tank 13, a second liquid level sensor 61 is provided in the recovery tank 13. In addition, the recovery tank 13 is connected to the gas-liquid separation tank 11 through the recovery pipe 14, and is connected to the liquefied gas pipeline 30 through the pressure equalizing pipe 16 and the reflux pipe 18. The recovery tank 13 stores the liquefied gas supplied from the gas-liquid separation tank 11, and guides the liquefied gas to the liquefied gas pipeline 30 through the reflux pipe 18. In addition, the recovery tank 13 is connected to the exhaust pipe 12 through the discharge pipe 21.

[0095] (Second liquid level sensor)

[0096] The second liquid level sensor 61 detects the liquid level of the liquefied gas in the recovery tank 13. The second liquid level sensor 61 can maintain the storage amount of the liquefied gas in the recovery tank 13 between the upper and lower limits, and guide the liquefied gas from the recovery tank 13 to the liquefied gas pipeline 30.

[0097] (pressure equalizing tube)

[0098] The pressure equalizing pipe 16 can make the gas phase area of ​​the recovery tank 13 and the gas phase area of ​​the liquefied gas pipeline 30 communicate with each other, and equalize the pressure of the recovery tank 13 and the liquefied gas pipeline 30. In this embodiment, the pressure equalizing pipe 16 makes the gas phase area of ​​the recovery tank 13 and the gas phase area of ​​the capture tank 38 of the liquefied gas pipeline 30 communicate with each other.

[0099] (Pressure equalizing stop valve)

[0100] The pressure-equalizing stop valve 17 is provided on the pressure-equalizing tube 16, and opens and closes the pressure-equalizing tube 16. For example, the gas in the pressure-equalizing tube 16 can be moved by opening the pressure-equalizing tube 16, and the movement of the gas in the pressure-equalizing tube 16 can be cut off by closing the pressure-equalizing tube 16. Hereinafter, the state in which the pressure-equalizing stop valve 17 closes the pressure-equalizing tube 16 is referred to as the closed state of the pressure-equalizing stop valve 17, and the state in which the pressure-equalizing stop valve 17 opens the pressure-equalizing tube 16 is referred to as the open state of the pressure-equalizing stop valve 17.

[0101] (Return pipe)

[0102] The reflux pipe 18 connects the recovery tank 13 with the liquefied gas pipeline 30. The reflux pipe 18 can deliver liquefied gas from the recovery tank 13 to the liquefied gas pipeline 30. In the present embodiment, the reflux pipe 18 connects the recovery tank 13 with the capture tank 38. The reflux pipe 18 is provided with a reflux stop valve 19 and a reflux pump 20 that can open and close the reflux pipe 18.

[0103] (Backflow cut-off valve)

[0104] The reflux stop valve 19 opens and closes the reflux pipe 18. The reflux stop valve 19 can, for example, allow the liquefied gas in the reflux pipe 18 to move by opening the reflux pipe 18, and on the other hand, can shut off the movement of the liquefied gas in the reflux pipe 18 by closing the reflux pipe 18. Hereinafter, the state in which the reflux stop valve 19 closes the reflux pipe 18 is referred to as the closed state of the reflux stop valve 19, and the state in which the reflux stop valve 19 opens the reflux pipe 18 is referred to as the open state of the reflux stop valve 19.

[0105] (Reflux pump)

[0106] The reflux pump 20 is provided in the reflux pipe 18 which is closer to the recovery tank 13 side than the reflux stop valve 19. The reflux pump 20 pressurizes and delivers the liquefied gas from the recovery tank 13 to the liquefied gas pipeline 30. In the present embodiment, the reflux pump 20 pressurizes and delivers the liquefied gas from the recovery tank 13 to the capture tank 38. The liquefied gas pressurized and delivered by the reflux pump 20 is introduced into the capture tank 38.

[0107] (Discharge pipe)

[0108] The discharge pipe 21 connects the inside of the recovery tank 13 with the outside of the recovery tank 13. In the present embodiment, the discharge pipe 21 connects the recovery tank 13 with the exhaust pipe 12, and connects the gas phase region of the gas-liquid separation tank 11 with the gas phase region of the recovery tank 13 via the exhaust pipe 12. A discharge stop valve 22 is provided on the discharge pipe 21.

[0109] (Discharge stop valve)

[0110] The discharge stop valve 22 opens and closes the discharge pipe 21. For example, the discharge stop valve 22 can allow the gas in the discharge pipe 21 to move by opening the discharge pipe 21, and can cut off the movement of the gas in the discharge pipe 21 by closing the discharge pipe 21. Hereinafter, the state in which the discharge stop valve 22 closes the discharge pipe 21 is referred to as the closed state of the discharge stop valve 22, and the state in which the discharge stop valve 22 opens the discharge pipe 21 is referred to as the open state of the discharge stop valve 22.

[0111] (Reflux step of liquefied gas)

[0112] In the above-mentioned ship 1 , the purged liquefied gas is guided to the gas-liquid separation tank 11 and then flows back to the liquefied gas pipeline 30 .

[0113] Below, reference Figure 3 The flowchart of FIG. 1 is used to explain the step of returning the purged liquefied gas to the liquefied gas pipeline 30. In addition, before the purging starts, the recovery stop valve 15, the pressure equalization stop valve 17, the reflux stop valve 19 and the discharge stop valve 22 are in a closed state.

[0114] First, the discharge stop valve 22 is opened to equalize the pressure of the gas-liquid separation tank 11 and the recovery tank 13 (step S1). In step S1, the recovery stop valve 15 is opened. In addition, when the discharge stop valve 22 and the recovery stop valve 15 are already opened and the pressure of the gas-liquid separation tank 11 and the recovery tank 13 is equalized, step S1 can be omitted.

[0115] In this state (initial state after completing step S1), the purge gas supply device 40 is operated to supply purge gas to the purge target area P to purge the purge target area P (step S2). When the purge is started, the liquefied gas guided from the purge target area P to the gas-liquid separation tank 11 is temporarily stored in the gas-liquid separation tank 11. At this time, the liquefied gas is stored in the gas-liquid separation tank 11 until the liquid level of the liquefied gas in the gas-liquid separation tank 11 is at least located above the lower limit position detected by the first liquid level sensor 60.

[0116] Hereinafter, the storage amount of the liquefied gas in the gas-liquid separation tank 11 when the liquid level of the liquefied gas in the gas-liquid separation tank 11 is at the lower limit position detected by the first liquid level sensor 60 is referred to as the minimum storage amount of the gas-liquid separation tank 11. The minimum storage amount of the gas-liquid separation tank 11 is an amount that can be regarded as the extent to which the gas-liquid separation tank 11 is in an empty state.

[0117] In the gas-liquid separation tank 11, the gas and liquid are separated into the liquefied gas in the liquid phase and the purge gas and boil-off gas of the liquefied gas in the gas phase.

[0118] Then, since the recovery stop valve 15 is in an open state, the liquefied gas in the liquid phase flows down from the gas-liquid separation tank 11 toward the recovery tank 13. In this way, the liquefied gas is recovered by the recovery tank 13 (step S3). Then, the liquid level of the liquefied gas in the gas-liquid separation tank 11 decreases.

[0119] Next, the first liquid level sensor 60 is used to detect whether the liquid level of the liquefied gas in the gas-liquid separation tank 11 is at the lower limit position, thereby determining whether the storage amount of the gas-liquid separation tank 11 is below the minimum storage amount (step S4). When the storage amount of the gas-liquid separation tank 11 is not below the minimum storage amount (step S4; "No"), the liquefied gas is continuously recovered (step S3). On the other hand, when the storage amount of the gas-liquid separation tank 11 is below the minimum storage amount (step S4; "Yes"), the recovery stop valve 15 and the discharge stop valve 22 are closed, and the recovery of the liquefied gas is stopped (step S5).

[0120] After step S5 is completed, the liquefied gas is stored in the recovery tank 13 until the liquid level of the liquefied gas in the recovery tank 13 is at least located above the lower limit position detected by the second liquid level sensor 61 .

[0121] Hereinafter, the storage amount of the liquefied gas in the recovery tank 13 when the liquid level of the liquefied gas in the recovery tank 13 is at the lower limit position detected by the second liquid level sensor 61 is referred to as the minimum storage amount of the recovery tank 13. The minimum storage amount of the recovery tank 13 is the amount at which the recovery tank 13 can be regarded as being empty.

[0122] Then, the pressure equalization stop valve 17 is opened to equalize the pressures of the recovery tank 13 and the liquefied gas pipeline 30 (step S6 ). More specifically, the recovery tank 13 and the capture tank 38 are equalized in pressure.

[0123] Then, the reflux stop valve 19 is opened and the reflux pump 20 is started. Then, the liquefied gas is sent from the recovery tank 13 to the liquefied gas pipeline 30. In this way, the liquefied gas refluxes to the liquefied gas pipeline 30 (step S7).

[0124] Next, the second liquid level sensor 61 is used to detect whether the liquid level of the liquefied gas in the recovery tank 13 is lower than the lower limit position, thereby determining whether the storage amount of the recovery tank 13 is below the minimum storage amount (step S8). When the storage amount of the recovery tank 13 is not below the minimum storage amount (step S8; "No"), the liquefied gas continues to flow back (step S7). On the other hand, when the storage amount of the recovery tank 13 is below the minimum storage amount (step S8; "Yes"), the reflux stop valve 19 and the equalizing pressure stop valve 17 are then closed to stop the reflux of the liquefied gas (step S9).

[0125] Then, the discharge stop valve 22 is opened to equalize the pressures of the gas-liquid separation tank 11 and the recovery tank 13 (step S10). In step S10, the recovery stop valve 15 is opened. Step S10 is a step for preparing for the next purge.

[0126] Through the steps described above, the step of returning the purged liquefied gas to the liquefied gas pipeline 30 is completed.

[0127] In the above-mentioned liquefied gas reflux step, each time the recovery stop valve 15, the pressure-equalizing stop valve 17, the reflux stop valve 19, and the discharge stop valve 22 are operated from the closed state to the open state, it is confirmed whether the recovery stop valve 15, the pressure-equalizing stop valve 17, the reflux stop valve 19, and the discharge stop valve 22 are in the open state, and, conversely, each time the recovery stop valve 15, the pressure-equalizing stop valve 17, the reflux stop valve 19, and the discharge stop valve 22 are operated from the open state to the closed state, it is confirmed whether the recovery stop valve 15, the pressure-equalizing stop valve 17, the reflux stop valve 19, and the discharge stop valve 22 are in the closed state. These confirmations can be performed with the naked eye or automatically by a control device not shown in the figure.

[0128] Furthermore, the above-mentioned liquefied gas reflow step may be performed manually or automatically by a control device (not shown).

[0129] (Effect)

[0130] According to the ship 1 of this embodiment, the following effects are achieved.

[0131] In this embodiment, the ship 1 includes a hull 2, a combustion machine 9, a gas-liquid separation tank 11, a recovery tank 13, a pressure equalizing pipe 16 and a return pipe 18. The liquefied gas tank 8 is arranged on the floating body and stores liquefied gas. The combustion machine 9 is arranged on the floating body and is driven by liquefied gas. The liquefied gas pipeline 30 connects the liquefied gas tank 8 and the combustion machine 9. The liquefied gas in the liquefied gas pipeline 30 is introduced into the gas-liquid separation tank 11 together with the purge gas. The recovery tank 13 is arranged below the gas-liquid separation tank 11. The liquefied gas stored in the gas-liquid separation tank 11 flows down to the recovery tank 13. The pressure equalizing pipe 16 connects the gas phase region of the recovery tank 13 with the gas phase region of the liquefied gas pipeline 30. The recovery pipe 18 can feed liquefied gas from the recovery tank 13 to the liquefied gas pipeline 30.

[0132] The liquefied gas in the gas-liquid separation tank 11 is transported to the recovery tank 13 due to gravity. Then, if the recovery tank 13 and the liquefied gas pipeline 30 are pressure-equalized by the pressure equalizing pipe 16, the liquefied gas in the recovery tank 13 is sent to the liquefied gas pipeline 30 through the reflux pipe 18. In this way, the ship 1 can send the liquefied gas stored in the gas-liquid separation tank 11 to the liquefied gas pipeline 30 again via the recovery tank 13. In addition, the liquefied gas in the gas-liquid separation tank 11 is recovered by the recovery tank 13, so that the gas-liquid separation tank 11 can be quickly emptied. Therefore, the amount of liquefied gas in the gas-liquid separation tank 11 that evaporates and is discharged into the atmosphere can be reduced. Therefore, the liquefied gas lost due to purging can be minimized, so that energy loss can be reduced.

[0133] Furthermore, the recovery tank 13 and the liquefied gas pipeline 30 are pressure-equalized by the pressure-equalizing pipe 16 , and the pressure difference between the recovery tank 13 and the liquefied gas pipeline 30 becomes smaller, so that the liquefied gas in the recovery tank 13 can be smoothly delivered to the liquefied gas pipeline 30 .

[0134] Furthermore, according to the above structure, when the liquefied gas is sent to the liquefied gas pipeline 30 through the reflux pipe 18, it is sufficient to equalize the pressure of the recovery tank 13 and the liquefied gas pipeline 30, and it is not necessary to equalize the pressure of the gas-liquid separation tank 11 and the liquefied gas pipeline 30. Therefore, it is sufficient to only set the recovery tank 13 as a pressure tank with a wide pressure range that can be adjusted from atmospheric pressure to the same high pressure as the liquefied gas pipeline 30, so there is no need to improve the pressure resistance of the gas-liquid separation tank 11. Furthermore, by providing the recovery tank 13, a high-pressure pump for sending the liquefied gas from the gas-liquid separation tank 11 to the liquefied gas pipeline 30 is not required.

[0135] And, sometimes be provided with the device such as the harm removal device (not shown) of diluting the gas in the gas-liquid separator 11 before being discharged to the atmosphere, but in this case, if the total amount of a large amount of liquefied gas that desires to be purged is harm removed, then the harm removal device is large-scale, or the required processing time of liquefied gas harm removal is lengthened. In contrast, according to the above-mentioned structure, the liquefied gas received by the gas-liquid separator 11 can be reused in the combustion machine 9, so the harm removal device can be miniaturized, or the required processing time of the harm removal of liquefied gas can be shortened. Especially, when the liquefied gas as the fuel of the combustion machine 9 is ammonia, the miniaturized effect of the harm removal device is more remarkable.

[0136] In the present embodiment, the ship 1 includes a reflux pump 20 . The recovery pump 20 is provided in the recovery pipe 18 , and pressurizes and delivers the liquefied gas from the recovery tank 13 to the liquefied gas pipeline 30 .

[0137] Thus, the ship 1 can deliver liquefied gas from the recovery tank 13 to the liquefied gas pipeline 30 through the reflux pump 20. Therefore, the ship 1 can deliver liquefied gas from the recovery tank 13 to the liquefied gas pipeline 30 regardless of the position of the recovery tank 13 relative to the liquefied gas pipeline 30. Therefore, the restrictions on the arrangement of the recovery tank 13 can be relaxed. Therefore, the recovery tank 13 can be arranged in the vacant space of the ship 1. Therefore, it sometimes contributes to the miniaturization of the ship 1.

[0138] Furthermore, the recovery tank 13 and the liquefied gas pipeline 30 are pressure-equalized by the pressure-equalizing pipe 16, so that the pressure difference between the recovery tank 13 and the liquefied gas is reduced. By starting the reflux pump 20 in this state, the liquefied gas can be pressurized and transported with less power. Therefore, a low-cost reflux pump 20 can be used, thereby reducing the manufacturing cost of the ship 1.

[0139] In this embodiment, the ship 1 includes a recovery pipe 14, a recovery stop valve 15, a pressure equalizing stop valve 17, and a reflux stop valve 19. The recovery pipe 14 guides the liquefied gas from the gas-liquid separation tank 11 to the recovery tank 13. The recovery stop valve 15 is provided on the recovery pipe 14 and can open and close the recovery pipe 14. The pressure equalizing stop valve 17 is provided on the pressure equalizing pipe 16 and can open and close the pressure equalizing pipe 16. The reflux stop valve 19 is provided on the reflux pipe 18 and can open and close the reflux pipe 18.

[0140] In the present embodiment, the recovery stop valve 15 is operated to open the recovery pipe 14, and the liquefied gas is delivered from the gas-liquid separation tank 11 to the recovery tank 13. If the supply of liquefied gas from the gas-liquid separation tank 11 to the recovery tank 13 is completed, the recovery stop valve 15 is operated to close the recovery pipe 14 to cut off the flow of the liquefied gas. Then, the pressure equalizing stop valve 17 is operated to open the pressure equalizing pipe 16, and the recovery tank 13 and the liquefied gas pipeline 30 are pressure-equalized. Next, the reflux stop valve 19 is operated to open the reflux pipe 18, and the liquefied gas is delivered from the recovery tank 13 to the liquefied gas pipeline 30.

[0141] In this way, by operating the recovery stop valve 15, the pressure equalization stop valve 17 and the reflux stop valve 19, the liquefied gas can be simply and reliably supplied from the gas-liquid separation tank 11 to the recovery tank 13 and from the recovery tank 13 to the liquefied gas pipeline 30. Therefore, the liquefied gas can be reused more effectively.

[0142] In this embodiment, the ship 1 includes a discharge pipe 21 and a discharge stop valve 22. The discharge pipe 21 allows the inside of the recovery tank 13 to communicate with the outside of the recovery tank 13. The discharge stop valve 22 is provided on the discharge pipe 21 and can open and close the discharge pipe 21.

[0143] In this embodiment, by operating the discharge stop valve 22 to open the discharge pipe 21, the gas in the gas phase in the recovery tank 13 can be discharged to the outside. As a result, the increase in the internal pressure of the recovery tank 13 is suppressed. Therefore, the pressure difference between the gas-liquid separation tank 11 and the recovery tank 13 becomes small, so the liquefied gas can be smoothly sent from the gas-liquid separation tank 11 to the recovery tank 13. Therefore, the liquefied gas can be reused more effectively.

[0144] <Second embodiment>

[0145] Below, reference Figure 4 , a ship (floating body) 201 according to a second embodiment of the present invention will be described. The same names and the same reference numerals are used for the same structures as those in the first embodiment, and the description thereof will be omitted as appropriate.

[0146] like Figure 4 As shown, the ship 201 of this embodiment includes a piping system 210 which is partially different from that of the first embodiment, and the piping system 210 includes a recovery tank 213 provided above the liquefied gas pipeline 30. In this embodiment, the recovery tank 213 is arranged above the capture tank 38.

[0147] (Effect)

[0148] According to the ship 201 of this embodiment, the following effects are achieved.

[0149] In addition, regarding the same structure as that of the above-mentioned embodiment, the same operation and effect as that of the above-mentioned embodiment are exerted.

[0150] In this embodiment, the recovery tank 213 is disposed above the liquefied gas pipeline 30 .

[0151] Thus, in a state where the liquefied gas pipeline 30 and the recovery tank 213 are pressure-equalized, the liquefied gas is sent from the recovery tank 213 to the liquefied gas pipeline 30 due to gravity. Therefore, it is not necessary to provide a pump for sending the liquefied gas from the recovery tank 213 to the liquefied gas pipeline 30. Therefore, it is sometimes possible to suppress an increase in the number of parts and reduce the manufacturing cost of the ship 201, and to contribute to the miniaturization of the ship 201.

[0152] <Third Embodiment>

[0153] Below, reference Figure 5 , a ship (floating body) 301 according to a third embodiment of the present invention will be described. The same names and the same reference numerals are used for the same structures as those in the first embodiment, and the description thereof will be omitted as appropriate.

[0154] like Figure 5 As shown, a ship 301 of the present embodiment includes a piping system 310 that is partially different from that of the first embodiment, and the piping system 310 includes a liquefied gas pipeline 330 that is partially different from that of the first embodiment.

[0155] The liquefied gas pipeline 330 has an introduction portion 331. As in the first embodiment, the introduction portion 331 is a mixing tank capable of temporarily storing the liquefied gas introduced from the liquefied gas tank 8 and the capture tank 38. The equalizing pipe 16 and the reflux pipe 18 of this embodiment connect the recovery tank 213 and the introduction portion 331, and the equalizing pipe 16 connects the gas phase area of ​​the recovery tank 213 and the gas phase area of ​​the introduction portion 331. In addition, in this embodiment, it is assumed that the reflux pump 20 is not provided on the reflux pipe 18, but as in the first embodiment, the reflux pump 20 may also be provided.

[0156] Furthermore, similarly to the second embodiment, the recovery tank 213 is provided above the liquefied gas pipeline 30 .

[0157] (Effect)

[0158] The ship 301 of this embodiment has the same structure as the above-mentioned embodiment. Therefore, the same structure as the above-mentioned embodiment can exert the same function and effect as the above-mentioned embodiment.

[0159] <Fourth embodiment>

[0160] Below, reference Figure 6 to Figure 7 , a ship (floating body) 401 according to a fourth embodiment of the present invention will be described. The same names and the same reference numerals are used for the same structures as those in the first embodiment, and the description thereof will be omitted as appropriate.

[0161] like Figure 6As shown, the ship 401 of this embodiment has a piping system 410 that is different from that of the first embodiment, and similarly to the second embodiment, the piping system 210 has a recovery tank 213 disposed above the liquefied gas pipeline 30. In addition, in this embodiment, the reflux pump 20 is not disposed on the reflux pipe 18, but similarly to the first embodiment, the reflux pump 20 may also be disposed.

[0162] Furthermore, in the present embodiment, the recovery tank 213 is designed to be small, and the volume of the recovery tank 213 is smaller than the maximum storage capacity of the liquefied gas in the gas-liquid separation tank 11 .

[0163] Furthermore, the second liquid level sensor (liquid level sensor) 461 of the present embodiment can detect the upper limit position and the lower limit position of the liquid level of the liquefied gas in the recovery tank 213. More specifically, the second liquid level sensor 461 has an upper limit position sensor 462 for detecting the upper limit position of the liquid level of the liquefied gas in the recovery tank 213 and a lower limit position sensor 463 for detecting the lower limit position of the liquid level of the liquefied gas in the recovery tank 213.

[0164] In addition, the second liquid level sensor 461 may be a single sensor and detect both the upper limit position and the lower limit position of the liquid level of the liquefied gas in the recovery tank 213 .

[0165] In addition, hereinafter, the storage amount of the liquefied gas in the recovery tank 213 when the liquid level of the liquefied gas in the recovery tank 213 is at the upper limit position detected by the second liquid level sensor 461 is referred to as the maximum storage amount of the recovery tank 213. The maximum storage amount of the recovery tank 213 is the amount that can be regarded as the recovery tank 213 being in a full liquid state.

[0166] (Reflux step of liquefied gas)

[0167] Hereinafter, a procedure for returning the purged liquefied gas to the liquefied gas pipeline 30 according to the present embodiment will be described.

[0168] The recovery tank 213 of the present embodiment is designed to be small, and therefore the liquefied gas needs to be supplied from the gas-liquid separation tank 11 to the recovery tank 213 in several times.

[0169] Below, reference Figure 7 , the step of delivering the liquefied gas stored in the gas-liquid separation tank 11 to the liquefied gas pipeline 30 when the recovery tank 213 is small is described. In addition, before the purge starts, the recovery stop valve 15, the pressure equalization stop valve 17, the reflux stop valve 19 and the discharge stop valve 22 are in a closed state.

[0170] First, the discharge stop valve 22 is opened to equalize the pressure of the gas-liquid separation tank 11 and the recovery tank 213 (step S1A). In step S1A, the recovery stop valve 15 is opened. In addition, when the discharge stop valve 22 and the recovery stop valve 15 are already opened and the pressure of the gas-liquid separation tank 11 and the recovery tank 213 is equalized, step S1A can be omitted.

[0171] In this state (initial state after completing step S1A), the purge gas supply device 40 is operated to supply purge gas to the purge target area P to purge the purge target area P (step S2A). When the purge is started, the liquefied gas guided from the purge target area P to the gas-liquid separation tank 11 is temporarily stored in the gas-liquid separation tank 11. At this time, the liquefied gas is stored in the gas-liquid separation tank 11 until the liquid level of the liquefied gas in the gas-liquid separation tank 11 is at least located above the lower limit position detected by the first liquid level sensor 60.

[0172] In the gas-liquid separation tank 11, the gas and liquid are separated into the liquefied gas in the liquid phase and the purge gas and boil-off gas of the liquefied gas in the gas phase.

[0173] Then, since the recovery stop valve 15 is in an open state, the liquefied gas in the liquid phase flows down from the gas-liquid separation tank 11 toward the recovery tank 213. In this way, the liquefied gas is recovered by the recovery tank 213 (step S3A).

[0174] Next, the first liquid level sensor 60 detects whether the liquid level of the liquefied gas in the gas-liquid separation tank 11 is below the lower limit position, thereby determining whether the storage amount of the gas-liquid separation tank 11 is less than the minimum storage amount (step S4A).

[0175] When the storage capacity of the gas-liquid separation tank 11 is not less than the minimum storage capacity (step S4A; "No"), the upper limit position sensor 462 detects whether the liquid level of the liquefied gas in the recovery tank 213 is higher than the upper limit position, thereby determining whether the storage capacity of the recovery tank 213 is greater than the maximum storage capacity (step S5A). When the storage capacity of the recovery tank 213 is not greater than the maximum storage capacity (step S5A; "No"), the liquefied gas is continuously recovered (step S3A).

[0176] On the other hand, when the storage amount of the recovery tank 213 is equal to or greater than the maximum storage amount (step S5A; Yes), the recovery stop valve 15 and the discharge stop valve 22 are closed to stop the recovery of the liquefied gas (step S6A).

[0177] Furthermore, even when the storage amount of the gas-liquid separation tank 11 is equal to or less than the minimum storage amount (step S4A; Yes), the recovery stop valve 15 and the discharge stop valve 22 are closed to stop the recovery of the liquefied gas (step S6A).

[0178] After step S6A is completed, the liquefied gas is stored in the recovery tank 213 until the liquid level of the liquefied gas in the recovery tank 213 is at least located above the lower limit position detected by the second liquid level sensor 461 .

[0179] Then, the pressure equalizing stop valve 17 is operated to open the pressure equalizing pipe 16 to equalize the pressures of the recovery tank 213 and the liquefied gas pipeline 30 (step S7A). More specifically, the recovery tank 213 and the capture tank 38 are equalized in pressure.

[0180] Then, the reflux stop valve 19 is opened. Then, the liquefied gas is transferred from the recovery tank 213 to the pipeline 30 by gravity. In this way, the liquefied gas refluxes to the liquefied gas pipeline 30 (step S8A).

[0181] Next, the lower limit position sensor 463 detects whether the liquid level of the liquefied gas in the recovery tank 213 is lower than the lower limit position, thereby determining whether the storage amount of the recovery tank 213 is below the minimum storage amount (step S9A). When the storage amount of the recovery tank 213 is not below the minimum storage amount (step S9A; "No"), the liquefied gas continues to flow back (step S8A).

[0182] On the other hand, when the storage capacity of the recovery tank 213 is below the minimum storage capacity (step S9A; "Yes"), the first liquid level sensor 60 detects whether the liquid level of the liquefied gas in the gas-liquid separation tank 11 is below the lower limit position, thereby determining whether the storage capacity of the gas-liquid separation tank 11 is below the minimum storage capacity (step S10A).

[0183] When the storage amount of the gas-liquid separation tank 11 is not less than the minimum storage amount (step S10A; No), the reflux stop valve 19 and the pressure equalization stop valve 17 are closed to stop the reflux of the liquefied gas (step S11A).

[0184] Then, the discharge stop valve 22 is opened to equalize the pressures of the gas-liquid separation tank 11 and the recovery tank 213 (step S12A). In step S12A, the recovery stop valve 15 is opened.

[0185] After completing step S12A, the process returns to step S3A and repeats the above series of processes.

[0186] On the other hand, when the storage amount of the gas-liquid separation tank 11 is less than the minimum storage amount (step S10A; Yes), the reflux stop valve 19 and the pressure equalization stop valve 17 are closed to stop the reflux of the liquefied gas (step S13A).

[0187] Then, the discharge stop valve 22 is opened to equalize the pressures of the gas-liquid separation tank 11 and the recovery tank 213 (step S14A). In step S14A, the recovery stop valve 15 is opened. Step S14A is a step for preparing for the next purge.

[0188] Through the steps described above, the step of returning the purged liquefied gas to the liquefied gas pipeline 30 is completed.

[0189] In the above-mentioned liquefied gas reflux step, each time the recovery stop valve 15, the pressure-equalizing stop valve 17, the reflux stop valve 19, and the discharge stop valve 22 are operated from the closed state to the open state, it is confirmed whether the recovery stop valve 15, the pressure-equalizing stop valve 17, the reflux stop valve 19, and the discharge stop valve 22 are in the open state, and, conversely, each time the recovery stop valve 15, the pressure-equalizing stop valve 17, the reflux stop valve 19, and the discharge stop valve 22 are operated from the open state to the closed state, it is confirmed whether the recovery stop valve 15, the pressure-equalizing stop valve 17, the reflux stop valve 19, and the discharge stop valve 22 are in the closed state. These confirmations can be performed with the naked eye or automatically by a control device not shown in the figure.

[0190] Furthermore, the above-mentioned liquefied gas reflow step may be performed manually or automatically by a control device (not shown).

[0191] (Effect)

[0192] According to the ship 401 of this embodiment, the following effects are achieved.

[0193] In addition, regarding the same structure as that of the above-mentioned embodiment, the same operation and effect as that of the above-mentioned embodiment are exerted.

[0194] In the present embodiment, the ship 401 includes a second liquid level sensor 461. The second liquid level sensor 461 can detect the upper limit position and the lower limit position of the liquid level of the liquefied gas in the recovery tank 213.

[0195] Thus, the second liquid level sensor 461 can detect that the storage amount of liquefied gas in the recovery tank 213 is above the maximum storage amount by detecting the upper limit position of the liquid level of the liquefied gas. Thus, as in the present embodiment, when a recovery tank 213 having a capacity smaller than that of the gas-liquid separation tank 11 is used, the introduction of liquefied gas above the capacity of the recovery tank 213 is suppressed. Furthermore, the second liquid level sensor 461 can detect that the storage amount of liquefied gas in the recovery tank 213 is below the minimum storage amount by detecting the lower limit position of the liquid level of the liquefied gas. Thus, when the discharge of liquefied gas from the recovery tank 213 is completed, the supply of liquefied gas from the gas-liquid separation tank 11 to the recovery tank 213 can be immediately switched. Therefore, the liquefied gas can be reused more effectively.

[0196] Furthermore, as described above, since a small recovery tank 213 can be used, the ship 401 can be miniaturized.

[0197] (Other Implementations)

[0198] As mentioned above, although the embodiment of the present invention is described in detail with reference to the drawings, the specific structure is not limited to this embodiment, and design changes and the like within the scope not departing from the gist of the present invention are also included.

[0199] In addition, in the above-mentioned embodiment, the floating body is described as a ship 1, 201, 301, 401 that sails on the ocean by using the heat energy generated by burning liquefied gas, but the present invention is not limited thereto. For example, the floating body may be a marine structure other than the ship 1, 201, 301, 401 that floats on the ocean. More specifically, the floating body may be a floating LNG storage and regasification unit (FSRU) transported by an LNG ship.

[0200] In the above embodiment, the purge gas supply pipe 42 is connected between the downstream supply stop valve 36 b in the supply pipe 33 and the combustion device 9 , but the present invention is not limited thereto. For example, the purge gas supply pipe 42 may be directly connected to the combustion device 9 .

[0201] In the above embodiments, the piping system 10 , 210 , 310 , 410 includes the drain pipe 21 and the drain stop valve 22 , but the present invention is not limited thereto and the piping system 10 , 210 , 310 , 410 may not include the drain pipe 21 and the drain stop valve 22 .

[0202] In the above embodiment, the pressure equalizing pipe 16 is described as connecting the recovery tank 13, 213 and the capture tank 38, and connecting the recovery tank 13, 213 and the introduction part 331, but the present invention is not limited thereto. For example, the pressure equalizing pipe 16 may be arranged to connect the area between the capture tank 38 and the introduction part 31 (or the introduction part 331) in the return pipe 34 and the recovery tank 13, 213.

[0203] <Note>

[0204] The floating body described in each embodiment can be understood, for example, as follows.

[0205] (1) The float involved in the first embodiment comprises: a float body; a liquefied gas tank 8, which is arranged on the float body and stores liquefied gas; a combustion machine 9, which is arranged on the float body and driven by liquefied gas; a liquefied gas pipeline 30, 330, which connects the liquefied gas tank 8 and the combustion machine 9; a gas-liquid separation tank 11, into which the liquefied gas in the liquefied gas pipeline 30, 330 is introduced together with the purge gas; a recovery tank 13, 213, which is arranged below the gas-liquid separation tank 11 and for the liquefied gas stored in the gas-liquid separation tank 11 to flow downward; a pressure equalizing pipe 16, which connects the gas phase region of the recovery tank 13, 213 with the gas phase region of the liquefied gas pipeline 30, 330; and a reflux pipe 18, which can feed liquefied gas from the recovery tank 13, 213 to the liquefied gas pipeline 30, 330.

[0206] Examples of floating bodies include the above-mentioned ships 1, 201, 301, 401, etc.

[0207] Furthermore, examples of the floating body include the above-mentioned hull 2 ​​and the like.

[0208] The liquefied gas in the gas-liquid separation tank 11 is transported to the recovery tank 13, 213 due to gravity. Then, if the recovery tank 13, 213 and the liquefied gas pipeline 30, 330 are pressure-equalized by the pressure equalizing pipe 16, the liquefied gas in the recovery tank 13, 213 is sent to the liquefied gas pipeline 30, 330 through the reflux pipe 18. In this way, the ship 1 can send the liquefied gas stored in the gas-liquid separation tank 11 to the liquefied gas pipeline 30, 330 again via the recovery tank 13, 213. In addition, the liquefied gas in the gas-liquid separation tank 11 is recovered by the recovery tank 13, 213, thereby enabling the gas-liquid separation tank 11 to be quickly emptied. Therefore, the amount of liquefied gas in the gas-liquid separation tank 11 that evaporates and is discharged into the atmosphere can be reduced.

[0209] In addition, the recovery tank 13, 213 and the liquefied gas pipeline 30, 330 are pressure-equalized by the pressure-equalizing pipe 16, so that the pressure difference between the recovery tank 13, 213 and the liquefied gas pipeline 30, 330 becomes smaller, so that the liquefied gas in the recovery tank 13, 213 can be smoothly delivered to the liquefied gas pipeline 30, 330.

[0210] (2) Floating Body of Second Embodiment In the floating body of the first embodiment, the recovery tank 213 may be provided above the liquefied gas pipelines 30 , 330 .

[0211] Thus, when the liquefied gas pipelines 30, 330 and the recovery tank 213 are pressure-equalized, the liquefied gas is sent from the recovery tank 213 to the liquefied gas pipelines 30, 330 by gravity. Therefore, a pump for sending the liquefied gas from the recovery tank 213 to the liquefied gas pipelines 30, 330 is not required.

[0212] (3) The floating body of the third aspect The floating body of the first aspect or the second aspect may include a reflux pump 20 that is provided in the reflux pipe 18 and that pressurizes and delivers the liquefied gas from the recovery tank 13 to the liquefied gas pipeline 30 .

[0213] Thus, the float can deliver liquefied gas from the recovery tank 13 to the liquefied gas pipeline 30 through the reflux pump 20. Therefore, the float can deliver liquefied gas from the recovery tank 13 to the liquefied gas pipeline 30 regardless of the position of the recovery tank 13 relative to the liquefied gas pipeline 30. Therefore, the restrictions on the arrangement of the recovery tank 13 can be relaxed.

[0214] (4) The floating body of the fourth aspect The floating body of any one of the first to third aspects may include a liquid level sensor capable of detecting an upper limit position and a lower limit position of the liquid level of the liquefied gas in the recovery tank 213 .

[0215] For example, as an example of the liquid level sensor, the second liquid level sensor 461 can be cited.

[0216] Thus, the liquid level sensor can detect that the storage amount of liquefied gas in the recovery tank 213 is above the maximum storage amount by detecting the upper limit position of the liquid level of the liquefied gas. Thus, when using the recovery tank 213 whose capacity is smaller than the gas-liquid separation tank 11, the feeding of liquefied gas exceeding the capacity of the recovery tank 213 is suppressed. Furthermore, the liquid level sensor can detect that the storage amount of liquefied gas in the recovery tank 213 is below the minimum storage amount by detecting the lower limit position of the liquid level of the liquefied gas. Thus, when the discharge of liquefied gas from the recovery tank 213 is completed, the supply of liquefied gas from the gas-liquid separation tank 11 to the recovery tank 213 can be immediately switched.

[0217] (5) The float of the fifth mode may include, in any one of the floats of the first to fourth modes: a recovery pipe 14 for guiding the liquefied gas from the gas-liquid separation tank 11 to the recovery tank 13, 213; a recovery stop valve 15, which is arranged on the recovery pipe 14 and is capable of opening and closing the recovery pipe 14; a pressure equalizing stop valve 17, which is arranged on the pressure equalizing pipe 16 and is capable of opening and closing the pressure equalizing pipe 16; and a reflux stop valve 19, which is arranged on the reflux pipe 18 and is capable of opening and closing the reflux pipe 18.

[0218] In this method, the recovery stop valve 15 is operated to open the recovery pipe 14, and the liquefied gas is transported from the gas-liquid separation tank 11 to the recovery tank 13, 213. If the supply of liquefied gas from the gas-liquid separation tank 11 to the recovery tank 13, 213 is completed, the recovery stop valve 15 is operated to close the recovery pipe 14 to cut off the flow of liquefied gas. Then, the pressure equalizing stop valve 17 is operated to open the pressure equalizing pipe 16, and the recovery tank 13, 213 and the liquefied gas pipeline 30, 330 are pressure-equalized. Next, the reflux stop valve 19 is operated to open the reflux pipe 18, and liquefied gas is sent from the recovery tank 13, 213 to the liquefied gas pipeline 30, 330.

[0219] In this way, by operating the recovery stop valve 15, the equalizing pressure stop valve 17 and the reflux stop valve 19, the liquefied gas can be simply and reliably supplied from the gas-liquid separation tank 11 to the recovery tank 13, 213 and from the recovery tank 13, 213 to the liquefied gas pipeline 30, 330.

[0220] (6) The floating body of the sixth aspect may include any of the floating bodies of the first to fifth aspects, including: a discharge pipe 21 that allows the inside of the recovery tank 13 , 213 to communicate with the outside of the recovery tank 13 , 213 ; and a discharge stop valve 22 that is provided in the discharge pipe 21 and can open and close the discharge pipe 21 .

[0221] In this embodiment, the gas phase in the recovery tank 13, 213 can be discharged to the outside by operating the discharge stop valve 22 to open the discharge pipe 21. As a result, the increase in the internal pressure of the recovery tank 13, 213 is suppressed. Therefore, the pressure difference between the gas-liquid separation tank 11 and the recovery tank 13, 213 becomes small, so that the liquefied gas can be smoothly fed from the gas-liquid separation tank 11 to the recovery tank 13, 213.

[0222] Industrial Applicability

[0223] According to the floating body of the present invention, energy loss can be reduced.

[0224] Explanation of symbols

[0225] 1- ship (floating body), 2- hull (floating body body), 3a- bow, 3b- stern, 4- superstructure, 5- side, 6- bottom, 7- upper deck, 8- liquefied gas tank, 9- combustion machine, 10- piping system, 11- gas-liquid separation tank, 12- exhaust pipe, 13- recovery tank, 14- recovery pipe, 15- recovery stop valve, 16- pressure equalizing pipe, 17- pressure equalizing stop valve, 18- reflux pipe, 19- reflux stop valve, 20- reflux pump, 21- discharge pipe, 22- discharge stop valve, 30- liquefied gas pipeline, 31- introduction part, 32- introduction pipe, 33- supply pipe, 34- return pipe, 35- supply pump, 36- supply stop valve, 36a- upstream side main fuel stop valve, 36b- downstream side supply stop valve, 37- return stop valve, 37a- upstream side return stop valve , 37b-downstream main fuel shut-off valve, 38-capture tank, 40-purge gas supply device, 41-purge gas supply unit, 42-purge gas supply pipe, 43-purge gas supply valve, 50-purge pipeline, 51-supply side purge pipe, 52-supply side purge valve, 53-return side purge pipe, 54-return side purge valve, 60-first liquid level sensor, 61-second liquid level sensor, 201-ship (floating body), 210-piping system, 213-recovery tank, 301-ship (floating body), 310-piping system, 331-introduction unit, 401-ship (floating body), 410-piping system, 461-second liquid level sensor (liquid level sensor), 462-upper limit position sensor, 463-lower limit position sensor, P-purge target area, S-fuel adjustment chamber.

Claims

1. A floating body, comprising: floating body main body; A liquefied gas tank, which is arranged on the floating body and stores liquefied gas; A combustion machine, which is arranged on the floating body and driven by liquefied gas; A liquefied gas pipeline connecting the liquefied gas tank and the combustion machine; A gas-liquid separation tank, into which the liquefied gas in the liquefied gas pipeline is introduced together with the purge gas; A recovery tank is arranged below the gas-liquid separation tank and is used to store the liquefied gas in the gas-liquid separation tank; A pressure equalizing pipe, which connects the gas phase region of the recovery tank with the gas phase region of the liquefied gas pipeline; and The reflux pipe can deliver liquefied gas from the recovery tank to the liquefied gas pipeline.

2. The floating body according to claim 1, wherein: The recovery tank is arranged above the liquefied gas pipeline. 3 . The floating body according to claim 1 , further comprising a reflux pump, the reflux pump being provided in the reflux pipe and configured to pressurize and deliver the liquefied gas from the recovery tank to the liquefied gas pipeline. 4 . The floating body according to claim 1 , further comprising a liquid level sensor capable of detecting an upper limit position and a lower limit position of a liquid level of the liquefied gas in the recovery tank.

5. The floating body according to claim 1 or 2, comprising: a recovery pipe for guiding the liquefied gas from the gas-liquid separation tank to the recovery tank; A recovery stop valve, which is disposed on the recovery pipe and is capable of opening and closing the recovery pipe; a pressure equalizing stop valve, which is disposed on the pressure equalizing pipe and is capable of opening and closing the pressure equalizing pipe; and The reflux cutoff valve is provided on the reflux pipe and is capable of opening and closing the reflux pipe.

6. The floating body according to claim 1 or 2, comprising: a discharge pipe for communicating the inside of the recovery tank with the outside of the recovery tank; and The discharge stop valve is provided on the discharge pipe and is capable of opening and closing the discharge pipe.

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