Handling method and handling device for liquefied gas

Abstract

To shorten the time of purge work for a pipe for transferring liquefied gas at the time of handling between a liquefied gas base and a transport ship.SOLUTION: Liquefied gas is handled between a liquefied gas base 1 and a liquefied gas transport ship 2. A first flange 3F of a first pipe 3 extending from the liquefied gas base 1, and comprising a first valve 51, and a second flange 4F of a second pipe 4 extending from the liquefied gas transport ship 2, and comprising a second valve 52 are connected while the first valve 51 and the second valve 52 are closed, and thereby an isolated pipe connection part PJ is formed between the first valve 51 and the second valve 52. Then, the pipe connection part PJ is evacuated by a vacuum pump 13. After that, the pipe connection part PJ is filled with nitrogen gas from a nitrogen gas tank 12. After that, the first valve 51 and the second valve 52 are opened, and the liquefied gas is transferred between the liquefied gas base 1 and the liquefied gas transport ship 2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a loading and unloading method and device for loading and unloading liquefied gas between a liquefied gas terminal and a liquefied gas carrier. [Background technology]

[0002] Loading and unloading operations, including the transfer of liquefied gas, are carried out between a storage tank at a liquefied gas base and a liquefied gas transport ship. During loading and unloading operations, a pipe extending from the liquefied gas base and a pipe extending from the transport ship are connected to form a loading and unloading pipe, and the liquefied gas is transported through the loading and unloading pipe. Since the connection operation is usually performed outdoors, air is present in the loading and unloading pipe. In order to prevent the flammable liquefied gas being loaded from coming into contact with oxygen in the air, a purging operation is required to remove the air present in the loading and unloading pipe before loading and unloading the liquefied gas.

[0003] As a specific means for the purging operation, pressure swing is known (Patent Document 1). In pressure swing, a pressurizing operation for supplying a purge gas to the loading pipe and a depressurizing operation for discharging the gas in the loading pipe are repeated. In the case of a loading pipe for liquefied hydrogen, the air in the loading pipe is first replaced with nitrogen gas, and then the nitrogen gas is replaced with hydrogen gas, and each of these purging operations is performed by pressure swing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-79998 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, with pressure swing, the gas in the transfer piping cannot be removed to a level that does not pose a problem unless the pressurization and depressurization operations are repeated a considerable number of times. In the case of liquefied hydrogen loading and unloading piping, in both the nitrogen gas replacement and hydrogen gas replacement described above, the pressurization and depressurization operations and gas concentration measurement operations must be repeated several dozens of times, which poses the problem of long work times.

[0006] An object of the present disclosure is to provide a loading / unloading method and loading / unloading device that can shorten the time required for purging piping that transports liquefied gas when loading / unloading between a liquefied gas terminal and a transport ship. [Means for solving the problem]

[0007] A method for loading and unloading liquefied gas according to one aspect of the present disclosure is a method for loading and unloading liquefied gas between a liquefied gas base and a transport ship, comprising the steps of: connecting an end of a first pipe extending from the liquefied gas base and having a first valve to an end of a second pipe extending from the transport ship and having a second valve with the first valve and the second valve closed, thereby forming a pipe connection portion that is disconnected between the first valve and the second valve; evacuating the pipe connection portion; filling the pipe connection portion with replacement gas; and opening the first valve and the second valve to transfer the liquefied gas between the liquefied gas base and the transport ship.

[0008] A liquefied gas loading and unloading device according to another aspect of the present disclosure is a loading and unloading device for loading and unloading liquefied gas between a liquefied gas base and a transport ship, comprising: a first pipe extending from the liquefied gas base and having a first valve, and connected to a second pipe extending from the transport ship and having a second valve; a vacuum pump capable of evacuating a decoupled pipe connection portion formed between the first valve and the second valve when the first valve and the second valve are closed and an end of the first pipe is connected to an end of the second pipe; and a replacement gas supply device capable of supplying replacement gas to the pipe connection portion. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a loading / unloading method and loading / unloading device that can shorten the time required for purging piping that transports liquefied gas when loading / unloading between a liquefied gas base and a transport ship. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a loading / unloading device according to a first embodiment to which the liquefied gas loading / unloading method of the present disclosure is applied. [Diagram 2] FIG. 2 is a diagram showing a process of forming a pipe connection, a process of drawing a vacuum at the pipe connection, and a process of filling the pipe connection with a replacement gas in the cargo handling method of the first embodiment. [Diagram 3] FIG. 3 is a diagram showing a process of transferring liquefied gas through a pipe connection in the cargo handling method of the first embodiment. [Figure 4] FIG. 4 is a diagram showing a process of pushing out liquefied gas from a pipe connection in the cargo handling method of the first embodiment. [Diagram 5] FIG. 5 is a diagram showing a pipe connection closing step and a pipe connection releasing step in the cargo handling method of the first embodiment. [Figure 6] FIG. 6 is a diagram showing a schematic configuration of a loading / unloading device according to a second embodiment to which the liquefied gas loading / unloading method of the present disclosure is applied. [Figure 7] FIG. 7 is a diagram showing a process of forming a pipe connection and a process of drawing a vacuum at the pipe connection in the cargo handling method according to the second embodiment. [Figure 8] FIG. 8 is a diagram showing a first step and a second step of filling a replacement gas into a pipe connection part in the loading and unloading method of the second embodiment. [Figure 9] FIG. 9 is a diagram showing a process of transferring liquefied gas through a pipe connection in the cargo handling method of the second embodiment. [Figure 10] FIG. 10 is a diagram showing a process of pushing out liquefied gas from a pipe connection in the cargo handling method of the second embodiment. [Figure 11] FIG. 11 is a diagram showing a process of evacuation of a pipe connection part and a process of filling with a replacement gas after transferring liquefied hydrogen in the loading and unloading method of the second embodiment. [Figure 12] FIG. 12 is a diagram for explaining a loading and unloading method of a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, with reference to the drawings, an embodiment of a liquefied gas loading method and loading device according to the present disclosure will be described in detail. The loading method and loading device according to the present disclosure are intended for loading and unloading liquefied gas between a liquefied gas base and a liquefied gas transport ship. In the following, a first embodiment is shown in which a replacement gas made of an inert gas introduced into a loading pipe is a liquefied gas that can be sent directly to a liquefied gas base or a liquefied gas transport ship, and a second embodiment is shown in which the replacement gas is a liquefied gas that cannot be sent directly. The liquefied gas in the first embodiment is, for example, liquefied natural gas (LNG). The liquefied gas in the second embodiment is, for example, liquefied hydrogen (LH2).

[0012] [First embodiment] <Configuration of cargo handling equipment> FIG. 1 is a diagram showing a schematic configuration of a liquefied gas loading / unloading device LF according to a first embodiment of the present disclosure. The loading / unloading device LF is a device for loading / unloading liquefied gas between a liquefied gas base 1 and a liquefied gas transport ship 2. The liquefied gas base 1 is a liquefied gas loading / unloading terminal equipped with loading / unloading equipment, and is a land facility for loading liquefied gas from a liquefied gas production facility or the like, or is a land facility for unloading liquefied gas. The liquefied gas transport ship 2 is a ship equipped with loading / unloading equipment that transports liquefied gas loaded from the liquefied gas base 1 or liquefied gas to be unloaded to the liquefied gas base 1 by sea.

[0013] The liquefied gas terminal 1 is provided with a liquefied gas storage tank 11, a nitrogen gas tank 12 (replacement gas supply device), a vacuum pump 13, a vent stack 14, a first transfer pump 15, a pressure gauge 16, a first pipe 3, and a temporary pipe 32. The liquefied gas transport ship 2 is equipped with a transport ship tank 21, a second transfer pump 22, and a second pipe 4. The first pipe 3 and the second pipe 4 are connected when loading and unloading liquefied gas, and become a loading and unloading pipe LP for transporting the liquefied gas.

[0014] The liquefied gas storage tank 11 is a tank installed on land and capable of storing low-temperature liquefied gas. In the first embodiment, the liquefied gas stored in the liquefied gas storage tank 11 is liquefied natural gas. Examples of the liquefied gas storage tank 11 include a flat-bottom cylindrical tank and a spherical tank having a multi-shell structure with a cold insulation layer.

[0015] The base end of the first pipe 3 is connected to the liquefied gas storage tank 11. The first pipe 3 is a pipe constituting the land-side loading and unloading pipe LP, and is a pipe extending from the liquefied gas base 1 in this embodiment. A first flange 3F is attached to the tip of the first pipe 3 extending from the liquefied gas base 1. A loading arm 31 equipped with a swivel joint 31J is interposed in the middle of the first pipe 3. The loading arm 31 allows the position of the first flange 3F to be freely adjusted.

[0016] The transport ship tank 21 is equipped on the liquefied gas transport ship 2 and is a tank capable of storing low-temperature liquefied gas, in this embodiment, liquefied natural gas. The base end of the second pipe 4 is connected to the transport ship tank 21. The second pipe 4 is a pipe constituting the ship-side loading and unloading pipe LP, and is a pipe extending from the liquefied gas transport ship 2 in this embodiment. A second flange 4F is attached to the extending tip of the second pipe 4 extending from the liquefied gas transport ship 2. During loading and unloading, the first flange 3F and the second flange 4F are flange-connected to form the loading and unloading pipe LP.

[0017] The nitrogen gas tank 12 is a tank that stores nitrogen gas as a replacement gas. The replacement gas is a gas that is introduced into the loading and unloading piping LP, and actually into the piping of the disconnected piping connection part PJ shown in FIG. 2 and the following. An inert gas other than nitrogen gas may be used as the replacement gas. The vacuum pump 13 is a pump that can draw a vacuum in the piping connection part PJ. For example, an oil rotary vacuum pump, a water ring vacuum pump, a dry vacuum pump, or the like can be used as the vacuum pump 13. The vent stack 14 is a facility that dilutes or renders harmless the gas purged from the piping connection part PJ and releases it into the atmosphere.

[0018] The first transfer pump 15 is incorporated into the first piping 3 and is capable of pumping out liquefied gas. The first transfer pump 15 operates when transferring liquefied gas from the liquefied gas storage tank 11 in the liquefied gas terminal 1 to the transport ship tank 21 of the liquefied gas transport ship 2. A first valve 51 for opening and closing the first piping 3 is incorporated into the first piping 3 at a position closer to the tip end than the first transfer pump 15, i.e., closer to the first flange 3F.

[0019] The second transfer pump 22 is incorporated into the second piping 4 and is capable of pumping out liquefied gas. The second transfer pump 22 operates when transferring liquefied gas from the transport ship tank 21 to the liquefied gas storage tank 11. A second valve 52 for opening and closing the second piping 4 is incorporated into the second piping 4 at a position closer to the tip end of the second transfer pump 22, that is, closer to the second flange 4F.

[0020] A temporary pipe 32 is attached to the first pipe 3. The temporary pipe 32 is a pipe for evacuating the pipe connection part PJ or for introducing replacement gas into the pipe connection part PJ. A first branch part 3J1 is provided at a position on the tip side of the first valve 51 of the first pipe 3. A base end of the temporary pipe 32 is connected to the first pipe 3 at the first branch part 3J1. A second branch part 3J2 is provided at the other end side of the temporary pipe 32. The temporary pipe 32 branches into a first branch pipe 33 and a second branch pipe 34 from the second branch part 3J2.

[0021] An end of the first branch pipe 33 is connected to the nitrogen gas tank 12. A third valve 53 for opening and closing the first branch pipe 33 is incorporated in the first branch pipe 33. A vacuum pump 13 is incorporated in the middle part of the second branch pipe 34. An end of the second branch pipe 34 is connected to the vent stack 14. A fourth valve 54 for opening and closing the second branch pipe 34 is incorporated in the second branch pipe 34 between the second branch portion 3J2 and the vacuum pump 13.

[0022] The pressure gauge 16 is a measuring instrument capable of measuring the pressure inside the piping. In Fig. 1, an example is shown in which the pressure gauge 16 is disposed between the fourth valve 54 of the second branch pipe 34 and the second branch section 3J2. The pressure gauge 16 measures the pressure in a closed space spanning the temporary piping 32 and the loading and unloading piping LP, which is formed by flange-connecting the first piping 3 and the second piping 4 and closing the four valves; the first valve 51, the second valve 52, the third valve 53, and the fourth valve 54.

[0023] <Loading and unloading method of the first embodiment> Next, a method for loading and unloading liquefied gas by the liquefied gas loading equipment LF having the configuration of Fig. 1 will be described with reference to Fig. 2 to Fig. 5. The loading and unloading method according to the first embodiment includes the following steps 1 to 7. Step 1 / Formation of pipe connection part: The first pipe 3 and the second pipe 4 are connected, and the first valve 51 to the fourth valve 54 are closed to form a disconnected pipe connection part PJ (FIG. 2). Step 2: Evacuation of the pipe connection: The inside of the disconnected pipe connection PJ is evacuated with a vacuum pump 13 (FIG. 2). Step 3: Filling the piping connection with replacement gas: Nitrogen gas is introduced from the nitrogen gas tank 12 into the evacuated piping connection PJ (FIG. 2). Step 4 / Transfer of liquefied gas: Using the loading and unloading piping LP, liquefied gas is transferred between the liquefied gas storage tank 11 and the transport ship tank 21 (Figure 3). Step 5 / Pushing out the liquefied gas: The liquefied gas remaining in the pipe connection part PJ is pushed out by the nitrogen gas supplied from the nitrogen gas tank 12 (FIG. 4). Step 6 / Closing the pipe connection part: The first valve 51 to the fourth valve 54 are closed to disconnect the pipe connection part PJ (FIG. 5). Step 7 / Disconnecting the pipe connection: Disconnect the first pipe 3 from the second pipe 4 (FIG. 5). Each of the above steps 1 to 7 will now be described in detail.

[0024] <Step 1 / Forming the piping connection> Before the liquefied gas loading / unloading equipment LF starts loading / unloading liquefied gas, the first flange 3F at the end of the first pipe 3 and the second flange 4F at the end of the second pipe 4 are in a disconnected state, and the first valve 51 to the fourth valve 54 are in a closed state, as shown in Fig. 1. The vacuum pump 13 is in a non-operating state, and the measurement value of the pressure gauge 16 is atmospheric pressure. In step 1, after the liquefied gas transport ship 2 arrives at the liquefied gas terminal 1, the first flange 3F and the second flange 4F are connected, as shown in Fig. 2.

[0025] This connection forms a loading pipe LP consisting of the first pipe 3 and the second pipe 4, which connects the liquefied gas storage tank 11 of the liquefied gas base 1 and the transport ship tank 21 of the liquefied gas transport ship 2. Furthermore, a pipe connection part PJ is formed between the first valve 51 and the second valve 52 in the loading pipe LP. The pipe connection part PJ becomes an isolated section that is isolated from the area of ​​the first pipe 3 closer to the liquefied gas storage tank 11 than the first valve 51 and the area of ​​the second pipe 4 closer to the transport ship tank 21 than the second valve 52 by closing the first valve 51 and the second valve 52. The temporary pipe 32 connected to the pipe connection part PJ is also isolated by closing the third valve 53 and the fourth valve 54. In other words, the internal space of the pipe connection part PJ and the temporary pipe 32 sandwiched between the first valve 51 and the fourth valve 54 is a closed space CS. In the current state, air is trapped in the closed space CS.

[0026] <Step 2 / Vacuuming the pipe connections> In step 2, among the first valve 51 to the fourth valve 54, only the fourth valve 54 is opened. Next, the vacuum pump 13 is put into operation. By operating the vacuum pump 13, the air in the closed space CS is exhausted through the vent stack 14, as shown by the arrow A1 in Fig. 2. Since it is air that is exhausted, the vent stack 14 does not perform any particular process.

[0027] Evacuation by the vacuum pump 13 is performed while monitoring the pressure gauge 16. When the pressure gauge 16 confirms that the specified vacuum level has been reached, the fourth valve 54 is closed and the vacuum pump 13 is stopped. By carrying out step 2, the air that was present in the disconnected pipe connection part PJ is substantially removed. In other words, purging of the pipe connection part PJ can be achieved in one go by evacuation in step 2. Therefore, the time required for the purging operation can be significantly reduced.

[0028] <Step 3 / Filling replacement gas into piping connections> In step 3, among the first valve 51 to the fourth valve 54, only the third valve 53 is opened. Since the closed space CS is depressurized to a predetermined vacuum level, when the third valve 53 is opened, the nitrogen gas in the nitrogen gas tank 12 flows into the piping of the closed space CS due to a pressure difference, as shown by the arrow A2. When a predetermined pressure, for example, atmospheric pressure, is confirmed by the pressure gauge 16, the third valve 53 is closed. By carrying out step 3, the closed space CS including the piping connection part PJ is filled with nitrogen gas. If liquefied gas is suddenly flowed into the evacuated piping connection part PJ, the liquefied gas may suddenly vaporize due to pressure fluctuations. By filling the piping connection part PJ with replacement gas before flowing the liquefied gas, the problem of vaporization can be suppressed.

[0029] <Step 4 / Transportation of liquefied gas> In step 4, as shown in Fig. 3, the first valve 51 and the second valve 52 are opened, and the third valve 53 and the fourth valve 54 are closed. That is, the liquefied gas storage tank 11 and the transport ship tank 21 are in communication with each other through the loading and unloading piping LP. Then, the liquefied gas is transferred between the liquefied gas storage tank 11 and the transport ship tank 21.

[0030] As shown by arrow F1 in Fig. 3, when liquefied gas is loaded from the liquefied gas terminal 1 to the liquefied gas transport ship 2, the first transfer pump 15 on the terminal side is operated. By operation of the first transfer pump 15, the liquefied gas stored in the liquefied gas storage tank 11 is sent to the transport ship tank 21 through the loading and unloading piping LP. Conversely, as shown by arrow F2, when liquefied gas is unloaded from the liquefied gas transport ship 2 to the liquefied gas terminal 1, the second transfer pump 22 on the ship side is operated. By operation of the second transfer pump 22, the liquefied gas stored in the transport ship tank 21 is sent to the liquefied gas storage tank 11 through the loading and unloading piping LP.

[0031] <Step 5 / Extrusion of liquefied gas> Step 5 is a step of pushing out the liquefied gas remaining in the pipe connection part PJ to the liquefied gas storage tank 11 or the transport ship tank 21. If step 4 is the transfer of the loaded liquefied gas, the first valve 51 is closed. On the other hand, if step 4 is the transfer of the unloaded liquefied gas, the second valve 52 is closed. Figure 4 shows the implementation status of step 5 after loading. Nitrogen gas in the nitrogen gas tank 12 is used as the pushing gas. For this reason, the third valve 53 is also opened.

[0032] After the liquefied gas is transferred using the loading / unloading piping LP, some liquefied gas that cannot be sent to the liquefied gas storage tank 11 or the transport ship tank 21 will remain in the loading / unloading piping LP. It is not appropriate to release the piping connection part PJ when liquefied gas remains. Therefore, gas that may be mixed into the tanks 11 and 12 is used as a pushing gas, and the liquefied gas remaining in the loading / unloading piping LP is sent to the tanks 11 and 12. In the first embodiment, liquefied natural gas is assumed as the liquefied gas. Nitrogen gas does not solidify due to the cold heat of liquefied natural gas. Therefore, the nitrogen gas used in the replacement gas filling in step 3 can be used as the pushing gas.

[0033] 4, the second valve 52 and the third valve 53 are opened, and nitrogen gas from the nitrogen gas tank 12 is supplied to the pipe connection part PJ through the temporary pipe 32. The liquefied gas remaining in the pipe connection part PJ is pushed by the supplied nitrogen gas and sent to the transport ship tank 21. In step 5 after unloading, the first valve 51 and the third valve 53 are opened, and the liquefied gas remaining in the pipe connection part PJ is sent to the liquefied gas storage tank 11.

[0034] <Step 6 / Closing the piping connections> In step 6, the pipe connection part PJ is again put into a disconnected state by closing all of the first valve 51 to the fourth valve 54. That is, the pipe connection part PJ and the temporary pipe 32 are made into a closed space. In this closed space, the nitrogen gas used as the pushing gas in the previous step 5 is present.

[0035] <Step 7 / Removing the piping connections> As shown in Fig. 6, in step 7, the flange connection between the first flange 3F of the first pipe 3 and the second flange 4F of the second pipe 4 is removed, and the pipe connection part PJ is released. The nitrogen gas in the closed space is released into the atmosphere by releasing the pipe connection part PJ. This allows the liquefied gas carrier 2 to leave the shore. This completes the loading and unloading of the liquefied gas.

[0036] <Advantages of Comparative Example and First Embodiment> The advantages of the first embodiment described above will be explained in comparison with a comparative example shown in Fig. 12. Fig. 12 is a diagram for explaining a loading and unloading method by a liquefied gas loading and unloading device LF0 of a comparative example using pressure swing. The same parts as in Fig. 2 are given the same reference numerals and will not be explained here. One end of a temporary pipe 320 is connected to a pipe connection part PJ. A first branch pipe 330 connected to a nitrogen gas tank 120 and a second branch pipe 340 connected to a vent stack 140 branch out from the other end of the temporary pipe 320. A third valve 53A is incorporated in the first branch pipe 330, and a fourth valve 54A is incorporated in the second branch pipe 340 for opening and closing the pipes.

[0037] In the purging by pressure swing, pressurization for filling the pipe connection part PJ with the replacement gas and depressurization for dissipating the replacement gas filled in the pipe connection part PJ are repeated. In the "pressurization", the first valve 51, the second valve 52 and the fourth valve 54A of the loading pipe LP are closed, and the third valve 53A is opened. In this state, nitrogen gas is pressurized from the nitrogen gas tank 120 into the pipe connection part PJ by the operation of a pump (not shown) arranged in the first branch pipe 330. When the pipe connection part PJ reaches a predetermined pressure, the fourth valve 54A is opened, while the third valve 53A is closed, and "depressurization" is performed. By opening the fourth valve 54A, the nitrogen gas pressurized into the pipe connection part PJ is exhausted through the vent stack 140.

[0038] In the pressure swing, the gas in the pipe connection part PJ is gradually replaced by the self-diffusion of nitrogen gas, so it is necessary to repeatedly execute the above-mentioned "pressurization" and "pressure reduction" while measuring the oxygen concentration in the pipe connection part PJ. In other words, it is necessary to repeat the set of "pressurization" and "pressure reduction" until it is confirmed that the oxygen concentration in the flammable liquefied gas has decreased to a level that does not cause problems. For this reason, purging the pipe connection part PJ requires a very long work time due to the repetition of the above set. Another problem is that a large amount of nitrogen gas is required.

[0039] In contrast, according to the loading and unloading method of the first embodiment, the air present in the pipe connection PJ can be instantly removed by evacuating the cut pipe connection PJ. Therefore, compared to the case where pressure swing is adopted, it is possible to shorten the time required for purging the pipe connection PJ, which is necessary before the transfer of liquefied gas between the liquefied gas base 1 and the liquefied gas carrier 2. In addition, since the gas is vented from the pipe connection PJ in one go, the oxygen concentration measurement work required in pressure swing can be omitted. Another advantage is that the amount of inert gas such as nitrogen gas used in the purging work can be significantly reduced.

[0040] [Second embodiment] <Configuration of cargo handling equipment> FIG. 6 is a diagram showing a schematic configuration of a liquefied gas loading / unloading device LFA according to a second embodiment. The loading / unloading device LFA is a device that loads and unloads liquefied hydrogen between a liquefied hydrogen terminal 1A and a liquefied hydrogen transport ship 2A. Hydrogen has an extremely low temperature of −253° C. in a liquid phase state, and solidifies nitrogen gas used as a replacement gas. In the second embodiment for loading and unloading liquefied hydrogen, loading and unloading work must take into consideration the solidification of nitrogen gas. In FIG. 6, the same reference numerals are attached to the same components as those in FIG. 1, and the description will be omitted or simplified here.

[0041] The liquefied hydrogen terminal 1A is a liquefied hydrogen loading / unloading terminal equipped with loading / unloading facilities, and is a land facility for loading liquefied hydrogen or a land facility for unloading liquefied hydrogen. The liquefied hydrogen transport ship 2A is a ship equipped with loading / unloading facilities that transports by sea the liquefied hydrogen loaded from the liquefied hydrogen terminal 1A or the liquefied hydrogen to be unloaded to the liquefied hydrogen terminal 1A.

[0042] The liquefied hydrogen base 1A is provided with a liquefied hydrogen storage tank 11A, a nitrogen gas tank 12 (replacement gas supply device), a vacuum pump 13, a vent stack 14, a first transfer pump 15, a pressure gauge 16, a BOG tank 17 (replacement gas supply device), a first pipe 3, and a temporary pipe 32. The liquefied hydrogen storage tank 11A is installed on land and is capable of storing liquefied hydrogen. The BOG tank 17 is a tank for storing boil-off gas of liquefied hydrogen generated in the liquefied hydrogen storage tank 11A and the equipment in the liquefied hydrogen base 1A. In addition to the first branch pipe 33 and the second branch pipe 34, the temporary pipe 32 further has a third branch pipe 35 connecting the second branch section 3J2 and the BOG tank 17. The third branch pipe 35 is provided with a fifth valve 55 for opening and closing the third branch pipe 35. The remaining configuration is the same as that of the first embodiment shown in FIG. 1.

[0043] The liquefied hydrogen transport ship 2A is equipped with a transport ship tank 21, a second transfer pump 22, and a second pipe 4. A second valve 52 is incorporated in the second pipe 4. The configuration of the liquefied hydrogen transport ship 2A is the same as that of the liquefied gas transport ship 2 described above, except that the storage object of the transport ship tank 21 is liquefied hydrogen.

[0044] <Loading and unloading method of the second embodiment> Next, a method for loading and unloading liquefied gas by the liquefied hydrogen loading and unloading equipment LFA having the configuration of Fig. 6 will be described with reference to Fig. 7 to Fig. 11. The loading and unloading method according to the second embodiment includes the following steps 11 to 18. Step 11 / Formation of pipe connection part: The first pipe 3 and the second pipe 4 are connected, and the first valve 51 to the fifth valve 55 are closed to form a disconnected pipe connection part PJ (FIG. 7). Step 12 / Evacuuming of pipe connection: The inside of the disconnected pipe connection PJ is evacuated by a vacuum pump 13 (FIG. 7). Step 13 / Filling of boil-off gas: Boil-off gas of liquefied hydrogen is introduced from the BOG tank 17 (Figure 8). Step 14 / Transfer of liquefied hydrogen: Using the loading and unloading piping LP, liquefied hydrogen is transferred between the liquefied hydrogen storage tank 11A and the transport ship tank 21 (FIG. 9). Step 15 / Pushing out liquefied hydrogen: The liquefied hydrogen remaining in the pipe connection part PJ is pushed out by the boil-off gas supplied from the BOG tank 17 (Figure 10). Step 16 / Vacuuming of pipe connection part: The pipe connection part PJ is disconnected and evacuated with the vacuum pump 13 to discharge the boil-off gas from the pipe connection part PJ (FIG. 11). Step 17 / Introduction of gas for releasing vacuum: Nitrogen gas is supplied from the nitrogen gas tank 12 to the pipe connection part PJ, and the pipe connection part PJ is returned to atmospheric pressure (FIG. 11). Step 18 / Disconnecting the pipe connection: The connection between the first pipe 3 and the second pipe 4 is disconnected (FIG. 11). Each of the above steps 11 to 18 will now be described in detail.

[0045] <Step 11 / Forming the piping connection> Before the liquefied hydrogen loading / unloading apparatus LFA starts unloading liquefied hydrogen, the first flange 3F of the first pipe 3 and the second flange 4F of the second pipe 4 are not connected, and the first valve 51 to the fifth valve 55 are closed, as shown in Fig. 6. The vacuum pump 13 is not in operation, and the measurement value of the pressure gauge 16 is atmospheric pressure. In step 11, the first flange 3F and the second flange 4F are connected, as shown in Fig. 7.

[0046] This connection forms a loading / unloading pipe LP that connects the liquefied hydrogen storage tank 11A and the transport ship tank 21. A pipe connection section PJ is formed between the first valve 51 and the second valve 52 in the loading / unloading pipe LP. The pipe connection section PJ becomes a disconnected section when the first valve 51 and the second valve 52 are closed. The temporary pipe 32 connected to the pipe connection section PJ is also disconnected when the third valve 53, the fourth valve 54, and the fifth valve 55 are closed. In other words, the internal space of the pipe connection section PJ and the temporary pipe 32 sandwiched between the first valve 51 to the fifth valve 55 becomes a closed space CS. In the current state, air is trapped in the closed space CS.

[0047] <Step 12 / Vacuuming the pipe connections> In step 2, of the first valve 51 to the fifth valve 55, only the fourth valve 54 is opened. Next, the vacuum pump 13 is put into operation. By operating the vacuum pump 13, the air in the closed space CS is exhausted through the vent stack 14, as shown by the arrow A11 in FIG. 7. The exhaust by the vacuum pump 13 is performed while monitoring the pressure gauge 16. When the predetermined vacuum level is confirmed by the pressure gauge 16, the fourth valve 54 is closed and the vacuum pump 13 is stopped. By the evacuation in step 12, the air is purged from the pipe connection part PJ in one go.

[0048] <Step 13 / Filling of boil-off gas> 8 is a diagram showing the implementation status of step 13. In step 13, boil-off gas of liquefied hydrogen is introduced from the BOG tank 17 to the pipe connection part PJ. Since all air has already been removed from the closed space CS in the previous step 12, there is no problem in introducing flammable boil-off gas into the closed space CS in this step 13.

[0049] Of the first valve 51 to the fifth valve 55, only the fifth valve 55 is opened in order to introduce hydrogen gas from the BOG tank 17 into the pipe connection part PJ. By opening the fifth valve 55, boil-off gas, i.e., hydrogen gas, flows from the BOG tank 17 into the evacuated closed space CS, as shown by arrow A12. When a predetermined pressure is confirmed by the pressure gauge 16, the fifth valve 55 is closed. By carrying out step 13, the closed space CS including the pipe connection part PJ is filled with hydrogen gas.

[0050] If gas replacement were to be performed without evacuation in step 12, a two-stage purge of the pipe connection part PJ would be required for the loading and unloading of liquefied hydrogen, where air would first be replaced with nitrogen gas, and then the nitrogen gas would be replaced with boil-off gas. If these purging operations were performed by pressure swing, it would take more time and effort than loading and unloading liquefied natural gas. Therefore, the time-saving effect of introducing the method according to the present disclosure, in which the gas is removed from the pipe connection part PJ in one go using the vacuum pump 13, is significant.

[0051] <Step 14 / Transportation of liquefied hydrogen> 9, in step 14, the first valve 51 and the second valve 52 are opened, and the third valve 53 to the fifth valve 55 are closed. That is, the liquefied hydrogen storage tank 11A and the transport ship tank 21 are placed in communication with each other via the loading and unloading piping LP, and the liquefied hydrogen is transferred.

[0052] As shown by arrow F1 in Fig. 9, when liquefied hydrogen is loaded from the liquefied hydrogen base 1A to the liquefied hydrogen transport ship 2A, the first transfer pump 15 on the base side is operated. By operation of the first transfer pump 15, the liquefied hydrogen stored in the liquefied hydrogen storage tank 11A is sent to the transport ship tank 21 through the loading and unloading piping LP. Conversely, as shown by arrow F2, when liquefied hydrogen is unloaded from the liquefied hydrogen transport ship 2A to the liquefied hydrogen base 1A, the second transfer pump 22 on the ship side is operated. By operation of the second transfer pump 22, the liquefied hydrogen stored in the transport ship tank 21 is sent to the liquefied hydrogen storage tank 11A through the loading and unloading piping LP.

[0053] <Step 15 / Extrusion of liquefied hydrogen> In step 5 of the first embodiment, nitrogen gas from the nitrogen gas tank 12 is used as a pushing gas for the liquefied gas remaining in the pipe connection part PJ. However, when pushing out liquefied hydrogen, nitrogen gas cannot be used as a pushing gas because it solidifies due to the cold heat of the liquefied hydrogen. Therefore, in step 15, boil-off gas of liquefied hydrogen, which does not solidify due to the cold heat of the liquefied hydrogen, is used as a pushing gas. That is, hydrogen gas, which is the boil-off gas of liquefied hydrogen stored in the BOG tank 17, is used to push out the liquefied hydrogen remaining in the pipe connection part PJ.

[0054] When step 14 is the transfer of liquefied hydrogen as a cargo, the first valve 51 is closed. On the other hand, when step 14 is the transfer of liquefied gas as a cargo, the second valve 52 is closed. FIG. 10 shows step 15 after loading. The boil-off gas in the BOG tank 17, which does not solidify at the liquefied hydrogen temperature, is used as the gas for pushing out. By opening the third valve 55, the boil-off gas in the BOG tank 17 is supplied to the pipe connection part PJ through the temporary pipe 32. As shown by the arrow A13, the liquefied hydrogen remaining in the pipe connection part PJ is pushed by the supplied boil-off gas and sent to the transport ship tank 21. In the case of step 15 after unloading, the first valve 51 and the fifth valve 55 are opened, and the liquefied hydrogen remaining in the pipe connection part PJ is pushed to the liquefied hydrogen storage tank 11A. After the liquefied hydrogen has been pushed out, the first valve 51 to the fifth valve 55 are fully closed. The closed space CS is filled with boil-off gas.

[0055] <Step 16 / Vacuuming the pipe connections> FIG. 11 is a diagram showing the execution status of steps 16 to 18. In step 16, in order to remove the boil-off gas from the pipe connection part PJ, the pipe connection part PJ in the disconnected state is evacuated by the vacuum pump 13. This step is intended to prevent the boil-off gas from coming into direct contact with oxygen in the air when the pipe connection part PJ is dismantled. Of the first valve 51 to the fifth valve 55, only the fourth valve 54 is opened, and the vacuum pump 13 is put into an operating state. By operating the vacuum pump 13, the air in the closed space CS is exhausted through the vent stack 14 as shown by the arrow A14 in FIG. 11. The vent stack 14 renders the boil-off gas harmless and releases it into the atmosphere. When a predetermined degree of vacuum is confirmed by the pressure gauge 16, the fourth valve 54 is closed and the vacuum pump 13 is stopped.

[0056] <Step 17 / Introducing gas to release the vacuum> Step 17 is a step for returning the closed space CS, which has been evacuated in the previous step 16, to atmospheric pressure. In step 17, only the third valve 53 is opened, and nitrogen gas from the nitrogen gas tank 12 is introduced into the piping of the closed space CS, as shown by the arrow A15. If the closed space CS is in a vacuum state, the first flange 3F and the second flange 4F cannot be disconnected, and the piping connection part PJ cannot be dismantled. For this reason, the closed space CS is returned to atmospheric pressure, making it possible to release the flange connection. The replacement gas for returning the pressure to atmospheric pressure may be any inert gas, but in this embodiment, nitrogen gas from the nitrogen gas tank 12 connected to the temporary piping 32 is used. When it is confirmed by the pressure gauge 16 that the closed space CS has returned to atmospheric pressure, the third valve 53 is closed.

[0057] <Step 18 / Removing the piping connections> In step 18, the flange connection between the first flange 3F of the first pipe 3 and the second flange 4F of the second pipe 4 is removed, and the pipe connection part PJ is released. The nitrogen gas in the closed space is released into the atmosphere by releasing the pipe connection part PJ. This completes the loading and unloading of liquefied hydrogen.

[0058] [Summary of this disclosure] The specific embodiments described above include disclosures having the following configurations.

[0059] A liquefied gas loading and unloading method according to a first aspect of the present disclosure is a method for loading and unloading liquefied gas between a liquefied gas base and a transport ship, comprising the steps of: connecting an end of a first pipe extending from the liquefied gas base and having a first valve to an end of a second pipe extending from the transport ship and having a second valve with the first valve and the second valve closed, thereby forming a pipe connection portion that is disconnected between the first valve and the second valve, evacuating the pipe connection portion, filling the pipe connection portion with replacement gas, and opening the first valve and the second valve to transfer the liquefied gas between the liquefied gas base and the transport ship.

[0060] According to the first aspect, the gas present in the disconnected pipe connection can be removed in one go by evacuating the disconnected pipe connection. Therefore, compared to the case of adopting pressure swing, it is possible to shorten the time required for purging the pipe connection, which is necessary before transferring liquefied gas between the liquefied gas base and the transport ship. In addition, since the gas is evacuated from the pipe connection in one go, the gas concentration measurement work required in pressure swing can be omitted. Furthermore, instead of suddenly passing liquefied gas through the evacuated pipe connection, the pipe connection is once filled with replacement gas and then the liquefied gas is transferred. Therefore, it is possible to suppress the liquefied gas from suddenly evacuating due to pressure fluctuations.

[0061] A method for loading and unloading a liquefied gas according to a second aspect is the method for loading and unloading a liquefied gas according to the first aspect, wherein the liquefied gas is liquefied hydrogen.

[0062] When the liquefied gas is liquefied hydrogen, it is necessary to thoroughly remove air from the piping connections before transferring the liquefied hydrogen in order to prevent a reaction between hydrogen and oxygen. For this reason, in the conventional pressure swing, the pressurization and depressurization work and the oxygen concentration measurement work must be repeated many times. However, according to the second aspect, the air in the piping connections is removed all at once by the vacuuming, so that the work can be completed in a short time even when loading and unloading liquefied hydrogen.

[0063] A third aspect of the liquefied gas loading and unloading method is the loading and unloading method of the second aspect, in which filling the piping connection part with a replacement gas includes a first filling of filling the evacuated piping connection part with an inert gas, and a second filling of replacing the inert gas filled in the piping connection part with hydrogen gas.

[0064] According to the third aspect, even when liquefied hydrogen is loaded, the pipe connection can be formed in an air environment. In addition, the two-stage purging of the first and second fillings can prevent hydrogen from coming into contact with oxygen. Furthermore, by using vacuum drawing for both of the two-stage purging, the purging operation time can be significantly reduced compared to pressure swing.

[0065] A fourth aspect of the liquefied gas loading and unloading method is the loading and unloading method of the first to third aspects, in which after the liquefied gas is transferred between the liquefied gas base and the transport ship, boil-off gas of the liquefied gas is supplied to the piping connection part, and the liquefied gas remaining in the piping connection part is pushed out through the first piping to the liquefied gas base side by opening the first valve, or pushed out through the second piping to the transport ship side by opening the second valve.

[0066] According to the fourth aspect, after the liquefied gas is transferred, the liquefied gas remaining in the pipe connection can be completely removed by boil-off gas, which makes it possible to easily dismantle the pipe connection after the transfer.

[0067] A fifth aspect of the liquefied gas loading method is the loading method of the fourth aspect, in which, after the pushing out by the boil-off gas, the first valve and the second valve are closed, the boil-off gas is sealed in the piping connection part, the piping connection part is evacuated, and the boil-off gas is discharged from the piping connection part.

[0068] According to the fifth aspect, after the residual liquefied gas is removed by the boil-off gas, the boil-off gas in the pipe connection can be removed in one go by vacuuming. This operation also requires less time than the pressure swing method.

[0069] A liquefied gas loading and unloading device according to a sixth aspect is a loading and unloading device for loading and unloading liquefied gas between a liquefied gas base and a transport ship, and includes a first pipe extending from the liquefied gas base and having a first valve, a second pipe extending from the transport ship and having a second valve, a vacuum pump capable of evacuating a decoupled pipe connection portion formed between the first valve and the second valve when the first valve and the second valve are closed and the end of the first pipe and the end of the second pipe are connected, and a replacement gas supply device capable of supplying replacement gas to the pipe connection portion.

[0070] According to the sixth aspect, since a vacuum pump is provided for evacuating the disconnected pipe connection, the gas present in the pipe connection can be removed in one go. Therefore, compared to the case where a pressure swing is used, it is possible to shorten the time required for purging the pipe connection before transferring the liquefied gas between the liquefied gas base and the transport ship. [Explanation of symbols]

[0071] LF Liquefied Gas Handling Equipment PJ piping connection CS closed space 1 Liquefied Gas Terminal 1A Liquefied Hydrogen Terminal 11 Liquefied gas storage tanks 11A Liquefied hydrogen storage tank 12 Nitrogen gas tank (replacement gas supply device) 13 Vacuum Pump 17 BOG tank (replacement gas supply device) 2. Liquefied gas carriers 2A Liquefied hydrogen carrier 21 Transport Tank 3. First Pipe 3F 1st flange (end of 1st pipe) 32, 33, 34, 35 1st, 2nd, 3rd, 4th branch pipes 4. Second piping 4F Second flange (tip of second pipe) 51 First valve 52 Second valve

Claims

1. A method for loading and unloading liquefied gas between a liquefied gas terminal and a transport ship, comprising the steps of: a first valve is provided at one end of a piping extending from the liquefied gas base, and a second valve is provided at one end of a piping extending from the transport ship, the second valve being provided at the other end of the piping, with the first valve and the second valve being closed, thereby forming a piping connection portion that is disconnected between the first valve and the second valve; The pipe connection is evacuated, Filling the piping connection with a replacement gas; A method for loading and unloading liquefied gas, comprising opening the first valve and the second valve to transport liquefied gas between the liquefied gas terminal and the transport ship.

2. The liquefied gas handling method according to claim 1, A method for loading and unloading liquefied gas, wherein the liquefied gas is liquefied hydrogen.

3. The liquefied gas handling method according to claim 2, The method for loading and unloading liquefied gas includes a first filling step of filling the piping connection part, which has been evacuated, with an inert gas, and a second filling step of replacing the inert gas filled in the piping connection part with hydrogen gas.

4. The liquefied gas handling method according to any one of claims 1 to 3, A method for loading and unloading liquefied gas, comprising: after transferring liquefied gas between the liquefied gas base and the transport ship, supplying boil-off gas of the liquefied gas to the piping connection portion; and opening the first valve and pushing the liquefied gas remaining in the piping connection portion toward the liquefied gas base side through the first piping; or opening the second valve and pushing the liquefied gas remaining in the piping connection portion toward the transport ship side through the second piping.

5. The method for loading and unloading liquefied gas according to claim 4, After the pushing out by the boil-off gas, the first valve and the second valve are closed to seal the boil-off gas in the piping connection portion; The piping connection part is evacuated to a vacuum, and the boil-off gas is discharged from the piping connection part.

6. A loading and unloading device for loading and unloading liquefied gas between a liquefied gas terminal and a transport ship, a first pipe extending from the liquefied gas terminal and having a first valve, the first pipe being connected to a second pipe extending from the transport ship and having a second valve; a vacuum pump capable of drawing a vacuum at a disconnected pipe connection portion formed between the first valve and the second valve in a state in which the first valve and the second valve are closed and an end of the first pipe and an end of the second pipe are connected; A replacement gas supply device capable of supplying a replacement gas to the piping connection portion; Liquefied gas loading and unloading equipment.

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