Ship and tank warm-up method

Abstract

A ship 1 comprises a tank 10 that stores gas generated by vaporization of low-temperature liquefied gas and cryogenic liquefied gas, a circulation line 20 that returns gas removed from the tank 10 back to the tank 10, a first heater 31 that is disposed on the circulation line 20 and that heats the gas flowing through the circulation line 20, a positive displacement compressor 30 that is disposed on the circulation line 20 downstream of the first heater 31 and that compresses the gas flowing through the circulation line 20, a bypass line 40 that supplies the gas from the tank 10 to a point downstream of the first heater 31 but upstream of the compressor 30, a first valve 60 that is disposed on the circulation line 20 upstream of the first heater 31 and that adjusts the flow rate of the gas supplied from the tank 10 to the first heater 31, and a second valve 61 that is disposed on the bypass line 40 and that adjusts the flow rate of the gas flowing through the bypass line 40.

Description

Method for warming up a ship and a tank

[0001] The present disclosure relates to a method for warming up a ship and a tank.

[0002] Patent Document 1 describes a method for warming up a liquefied gas storage tank by introducing a heating gas into the liquefied gas storage tank.

[0003] Japanese Unexamined Patent Application Publication No. 2023-140783

[0004] Patent Document 1 does not describe the efficiency of introducing the heating gas into the liquefied gas storage tank, and there is room for improvement in shortening the time required for warming up.

[0005] An object of the present disclosure is to provide a method for warming up a ship and a tank that can shorten the time required for warming up the tank.

[0006] One aspect of the present disclosure includes: at least one tank for storing cryogenic liquefied gas and the gas generated by vaporization of the cryogenic liquefied gas; a circulation line for returning the gas taken out from the at least one tank to the at least one tank; a heater disposed on the circulation line for heating the gas flowing through the circulation line; a positive-displacement compressor disposed on the circulation line and downstream of the heater for compressing the gas flowing through the circulation line; at least one bypass line disposed corresponding to the at least one tank for supplying gas from the corresponding tank to downstream of the heater and upstream of the compressor; and a flow rate adjusting device for adjusting the flow rate of the gas taken out from the at least one tank, flowing through the circulation line, heated by the heater, and then supplied to the compressor, or the flow rate of the gas taken out from the at least one tank, flowing through the corresponding bypass line, and supplied to the compressor. A ship is provided.

[0007] In this specification, "cryogenic liquefied gas" means a liquefied gas whose boiling point is -183°C or lower at atmospheric pressure. Examples of "cryogenic liquefied gases" include liquefied hydrogen, liquefied nitrogen, and liquefied helium. In this specification, "cryogenic" may also refer to a temperature of -183°C or lower.

[0008] The molecular weight of cryogenic liquefied gases is generally very small, and the gas density of the gas generated when cryogenic liquefied gases vaporize is also generally very low. When a turbo-type compressor is used to pump the gas taken out of a tank back into the tank, if the gas density of the gas taken out of the tank is excessively low, sufficient discharge pressure may not be obtained to return the gas to the tank. As a result, the time required for tank warm-up may be extended. In contrast, according to the vessel of this disclosure, a positive displacement compressor is used to pump the gas taken out of the tank back into the tank, so even if the gas density of the gas taken out of the tank is low, sufficient discharge pressure can be obtained to return the gas to the tank. As a result, the time required for warm-up can be shortened.

[0009] The higher the gas density of the gas drawn into the compressor, that is, the lower the temperature of the gas drawn into the compressor, the greater the volumetric flow rate of the gas discharged from the compressor. Therefore, the lower the temperature of the gas drawn into the compressor, the more efficiently the tank can be warmed up. In the vessel according to this disclosure, a portion of the gas taken out of the tank is supplied to the compressor without being heated by a heater by passing through a bypass line. Furthermore, the temperature of the gas drawn into the compressor can be adjusted by changing the opening of the first valve to adjust the flow rate of the gas heated by the heater and supplied to the compressor, and by changing the opening of the second valve to adjust the flow rate of the gas supplied to the compressor without being heated by the heater. Therefore, by adjusting the temperature of the gas drawn into the compressor to an appropriate temperature that takes into account the efficiency of tank warm-up, the time required for warm-up can be shortened. For example, by adjusting the temperature of the gas drawn into the compressor to the lowest possible temperature within the range of intake temperatures in which the compressor can operate, the time required for tank warm-up can be shortened.

[0010] This disclosure provides a vessel and a warm-up method that can reduce the time required for warming up a tank.

[0011] Figure 1 is a schematic diagram showing the configuration of a vessel according to one embodiment of the present disclosure. Figure 2 is a graph showing the temperature changes inside a tank in a tank warm-up method according to one embodiment of the present disclosure. Figure 3 is a diagram illustrating a tank warm-up method according to one embodiment of the present disclosure. Figure 4 is a diagram illustrating a tank warm-up method according to one embodiment of the present disclosure. Figure 5 is a diagram illustrating a tank warm-up method according to one embodiment of the present disclosure. Figure 6 is a diagram illustrating a tank warm-up method according to one embodiment of the present disclosure. Figure 7 is a diagram illustrating a tank warm-up method according to one modification of the above embodiment.

[0012] A method for warming up a vessel and a tank according to one embodiment of this disclosure will be described below with reference to the attached drawings.

[0013] Figure 1 is a schematic diagram showing the configuration of a vessel 1 according to one embodiment of the present disclosure. The vessel 1 according to this embodiment is a liquefied hydrogen carrier for transporting liquefied hydrogen. The liquefied hydrogen in this embodiment is an example of cryogenic liquefied gas according to the present disclosure.

[0014] Referring to Figure 1, the vessel 1 is equipped with three tanks 10A to 10C and a circulation line 20. In the following description, when it is not necessary to distinguish between the three tanks 10A to 10C, one of the three tanks 10A to 10C may simply be referred to as tank 10.

[0015] Tank 10 is a cargo tank that stores liquefied hydrogen as cargo and hydrogen gas generated when liquefied hydrogen vaporizes.

[0016] The circulation line 20 is a flow path that returns gas taken from tanks 10A to 10C to tanks 10A to 10C after heating it. The circulation line 20 is composed of multiple pipes. In the following description, the upstream of the gas flow in the circulation line 20 may be simply referred to as "upstream," and the downstream of the gas flow in the circulation line 20 may be simply referred to as "downstream."

[0017] The vessel 1 is equipped with a compressor 30, a first heater 31, and a second heater 32. The compressor 30, the first heater 31, and the second heater 32 are arranged on a circulation line 20. The compressor 30, the first heater 31, and the second heater 32 are arranged in the order of first heater 31, compressor 30, and second heater 32 from upstream to downstream in the circulation line 20.

[0018] The compressor 30 pressurizes and pumps the gas in the circulation line 20 toward the tank 10. In other words, the compressor 30 pressurizes the gas in the circulation line 20 and sends it toward the tank 10. The compressor 30 in this embodiment is a positive displacement compressor. In particular, the compressor 30 in this embodiment is a reciprocating compressor. The compressor 30 has an operating range of suction temperatures.

[0019] The first heater 31 is located upstream of the compressor 30. In other words, the first heater 31 is located on the suction side of the compressor 30. The first heater 31 is supplied with gas taken from the tank 10. The gas taken from each of the tanks 10A to 10C flows through separate pipes, merges upstream of the first heater 31, and is then supplied to the first heater 31. In other words, the pipes supplying gas from each of the tanks 10A to 10C to the first heater 31 merge upstream of the first heater 31. The first heater 31 functions as a preheater, preheating the gas supplied to the compressor 30.

[0020] The second heater 32 is located downstream of the compressor 30. In other words, the second heater 32 is located on the discharge side of the compressor 30. The second heater 32 is pressurized by the compressor 30 and heats the gas flowing through the circulation line 20 toward the tank 10. The second heater 32 functions as an afterheater, heating the gas discharged from the compressor 30. The gas heated by the second heater 32 flows through a single pipe, then branches upstream of the tank 10 and flows toward tanks 10A to 10C, respectively.

[0021] Ship 1 is equipped with three bypass lines 40A to 40C, each corresponding to one of the three tanks 10A to 10C. In the following description, when there is no need to distinguish between the three bypass lines 40A to 40C, one of the three bypass lines 40A to 40C may simply be referred to as bypass line 40.

[0022] The bypass line 40 is a flow path that directs the gas flowing upstream of the first heater 31 in the circulation line 20 to a location downstream of the first heater 31 and upstream of the compressor 30, without passing through the first heater 31. The bypass line 40 fluidly connects the upstream and downstream of the first heater 31. The bypass line 40 is composed of multiple pipes. The bypass lines 40A to 40C are fluidly connected to the circulation line 20 at their respective first connection points 21A to 21C. The bypass lines 40A to 40C are fluidly connected to the circulation line 20 at their respective second connection points 22A to 22C. The first connection points 21A to 21C are located downstream of their respective tanks 10A to 10C and upstream of the first heater 31, while the second connection points 22A to 22C are located downstream of the first heater 31 and upstream of the compressor 30. In the following explanation, if there is no need to distinguish between the first connection points 21A to 21C, one of the first connection points 21A to 21C may simply be referred to as the first connection point 21. Similarly, in the following explanation, if there is no need to distinguish between the second connection points 22A to 22C, one of the second connection points 22A to 22C may simply be referred to as the second connection point 22.

[0023] The vessel 1 is equipped with a branch line 50 and a processing device 51.

[0024] The branch line 50 branches off from the circulation line 20 and is a passage for sending the gas flowing through the circulation line 20 to the treatment device 51. One end of the branch line 50 is fluidically connected to the circulation line 20 at a branching point 23 located downstream of the compressor 30 and upstream of the second heater 32, and the other end of the branch line 50 is fluidly connected to the treatment device 51.

[0025] The processing unit 51 processes hydrogen gas supplied via the branch line 50. The processing unit 51 in this embodiment is a gas combustion unit (GCU) that co-fires the supplied hydrogen gas with other fuels such as oil fuel. In order to process hydrogen gas using the processing unit 51 in this embodiment, the pressure of the hydrogen gas supplied to the processing unit 51 must be above a predetermined pressure. For this reason, the compressor 30 in this embodiment is controlled so that the discharge pressure is above the predetermined pressure.

[0026] Ship 1 is equipped with three first valves 60A to 60C, each corresponding to one of the three tanks 10A to 10C. In the following description, when there is no need to distinguish between the first valves 60A to 60C, one of the first valves 60A to 60C may simply be referred to as the first valve 60.

[0027] The first valve 60 is located on the circulation line 20. The first valve 60 is located between the corresponding tank 10 and the first heater 31. More specifically, the first valve 60 is located downstream of the corresponding first connection point 21 and upstream of the first heater 31. The first valve 60 is a flow control valve that can adjust the flow rate by changing its opening. The first valve 60 may be able to adjust the flow rate continuously or in steps. By adjusting the flow rate through the first valve 60, the flow rate of gas supplied from the corresponding tank 10 to the first heater 31 is adjusted. The first valve 60 in this embodiment is an example of a flow rate adjustment device according to the present disclosure.

[0028] Ship 1 is equipped with two second valves 61A to 61C, each corresponding to one of the three bypass lines 40A to 40C. In the following description, when there is no need to distinguish between the three second valves 61A to 61C, one of the three second valves 61A to 61C may simply be referred to as second valve 61.

[0029] The second valve 61 is located on the corresponding bypass line 40. The second valve 61 is a flow control valve that can adjust the flow rate by changing its opening. The second valve 61 may be able to adjust the flow rate continuously or in steps. By adjusting the flow rate through the second valve 61, the flow rate of the gas flowing through the corresponding bypass line 40 is adjusted. The second valve 61 in this embodiment is an example of a flow rate adjustment device according to the present disclosure.

[0030] The vessel 1 is equipped with a third valve 62, a fourth valve 63, and three fifth valves 64A to 64C that correspond one-to-one to three tanks 10A to 10C. In the following description, when there is no need to distinguish between the three fifth valves 64A to 64C, one of the fifth valves 64A to 64C may simply be referred to as the fifth valve 64.

[0031] The third valve 62 is located on the circulation line 20. The third valve 62 is located downstream of the branching point 23 between the circulation line 20 and the branch line 50 and upstream of the second heater 32. The third valve 62 is a flow control valve that can adjust the flow rate by changing its opening. The third valve 62 may be able to adjust the flow rate continuously or in steps. By adjusting the flow rate through the third valve 62, the flow rate of gas supplied to the second heater 32 is adjusted.

[0032] The fourth valve 63 is located on the branch line 50. The fourth valve 63 is a flow control valve that can adjust the flow rate by changing its opening. The fourth valve 63 may be able to adjust the flow rate continuously or in steps. By adjusting the flow rate through the fourth valve 63, the flow rate of gas supplied to the processing device 51 is adjusted.

[0033] The fifth valve 64 is located on the circulation line 20. The fifth valve 64 is located upstream of the corresponding tank 10. The fifth valve 64 is a flow control valve that can adjust the flow rate by changing its opening. The fifth valve 64 may be able to adjust the flow rate continuously or in steps. By adjusting the flow rate through the fifth valve 64, the flow rate of gas returned to the corresponding tank 10 is adjusted.

[0034] Ship 1 is equipped with three first thermometers 70A to 70C, each corresponding to one of the three tanks 10A to 10C. In the following description, when there is no need to distinguish between the first thermometers 70A to 70C, one of the first thermometers 70A to 70C may simply be referred to as the first thermometer 70. The first thermometer 70 measures the temperature inside the corresponding tank 10.

[0035] Ship 1 is equipped with three first pressure gauges 71A to 71C, each corresponding to one of the three tanks 10A to 10C. In the following description, when there is no need to distinguish between the first pressure gauges 71A to 71C, one of the first pressure gauges 71A to 71C may simply be referred to as the first pressure gauge 71. The first pressure gauge 71 measures the pressure in the corresponding tank 10.

[0036] The vessel 1 is equipped with a second thermometer 72 and a second pressure gauge 73 located on the circulation line 20. The second thermometer 72 is located upstream of the compressor 30, i.e., on the suction side. The second thermometer 72 measures the temperature of the gas drawn into the compressor 30. The second pressure gauge 73 is located downstream of the compressor 30, i.e., on the discharge side. The second pressure gauge 73 measures the pressure downstream of the compressor 30 in the circulation line 20. More specifically, the second pressure gauge 73 measures the pressure downstream of the compressor 30 and upstream of the branching point 23.

[0037] The vessel 1 is equipped with a control device 80. The control device 80 consists of hardware such as a computer and input / output circuits, and software implemented on the hardware. The control device 80 is electrically connected to a first thermometer 70, a first pressure gauge 71, a second thermometer 72, a second pressure gauge 73, first to fifth valves 60 to 64, a compressor 30, a first heater 31, and a second heater 32. The control device 80 receives measurement data from each of the first thermometer 70, first pressure gauge 71, second thermometer 72, and second pressure gauge 73. The control device 80 uses the measurement data received from each of the first thermometer 70, first pressure gauge 71, second thermometer 72, and second pressure gauge 73 to control the opening of the first to fifth valves 60 to 64, as well as the operation of the compressor 30, the first heater 31, and the second heater 32.

[0038] [Tank Warm-up Method] The warm-up method for the tank 10 according to this embodiment will be described below with reference to Figures 2 to 6. Figure 2 is a graph showing the temperature changes inside tanks 10A to 10C during the warm-up of tank 10. In the graph shown in Figure 2, the vertical axis represents the temperature inside each tank 10 [arbitrary unit], and the horizontal axis represents the elapsed time since the start of warm-up [arbitrary unit]. Figures 3 to 6 are diagrams for explaining the warm-up method for the tank 10 according to this embodiment. Figures 3 to 6 show the state of the ship 1 at times t1 to t4 shown in Figure 2, respectively.

[0039] The warm-up of tank 10 is performed to raise the temperature inside tanks 10A to 10C to a target temperature Tg before inspection or repair of the vessel 1. In the warm-up method of this embodiment, the tank 10 is heated using the cryogenic gas present in tank 10 at the start of the warm-up. Specifically, in the warm-up method of this embodiment, tank 10, which has an initial temperature Ti at the start of the warm-up, is heated to a target temperature Tg using the gas present in tank 10.

[0040] The warm-up of tank 10 is performed by heating and pressurizing the gas taken from tank 10 to the circulation line 20 and returning it to tank 10. In this warm-up method, the warm-up of tanks 10A to 10C is started sequentially. In this warm-up method, the warm-up is stopped sequentially from tank 10 as it reaches the target temperature Tg. This warm-up method ends when all tanks 10A to 10C have reached the target temperature Tg. This warm-up method is executed by the control device 80 controlling the opening degrees of the first to fifth valves 60 to 64, as well as the operation of the compressor 30, the first heater 31, and the second heater 32.

[0041] Referring to Figure 2, first, the warm-up of tank 10A begins. As shown in Figure 3, tank 10A is warmed up when the gas taken out of tank 10A flows through the circulation line 20, is heated and pressurized, and then returned to tank 10A.

[0042] As shown in Figure 3, during the warm-up of tank 10A, the control device 80 opens the first valve 60A, the second valve 61A, and the fifth valve 64A, and operates the compressor 30 with the first valves 60B, 60C, the second valves 61B, 61C, and the fifth valves 64B, 64C closed. As a result, gas is drawn from tank 10A into the circulation line 20, while no gas is drawn from tanks 10B and 10C into the circulation line 20.

[0043] A portion of the gas extracted from tank 10A is heated by the first heater 31 and supplied to the compressor 30, while the remaining gas extracted from tank 10A passes through the bypass line 40A and is supplied to the compressor 30 without being heated by the first heater 31. In other words, downstream of the first heater 31 and upstream of the compressor 30, the gas heated and warmed by the first heater 31 and the gas that bypasses the first heater 31 and is not heated by the first heater 31 merge. As a result, downstream of the first heater 31 and upstream of the compressor 30, the relatively high-temperature gas that passed through the first heater 31 and the relatively low-temperature gas that flowed through the bypass line 40A are mixed.

[0044] As the flow rate of the gas passing through the first valve 60A increases, or as the flow rate of the gas passing through the second valve 61A decreases, the flow rate of the gas passing through the first heater 31 increases, while the flow rate of the gas flowing through the bypass line 40A decreases. As a result, the temperature of the gas sucked into the compressor 30 increases as the flow rate of the gas passing through the first valve 60A increases, or as the flow rate of the gas passing through the second valve 61A decreases.

[0045] In the warm-up of the tank 10A, the opening degree of the first valve 60A and the opening degree of the second valve 61A are controlled so that the temperature of the gas sucked into the compressor 30 becomes a predetermined reference temperature Ta. Specifically, in the warm-up of the tank 10A, the control device 80 controls the opening degree of the first valve 60A and the opening degree of the second valve 61A so that the temperature measured by the second thermometer 72 becomes the predetermined reference temperature Ta.

[0046] The predetermined reference temperature Ta is set in consideration of the warm-up efficiency. The higher the gas density of the gas sucked into the compressor 30, that is, the lower the temperature of the gas sucked into the compressor 30, the greater the volume flow rate of the gas discharged from the compressor 30. For this reason, the lower the temperature of the gas sucked into the compressor 30, the more the flow rate of the gas flowing through the circulation line 20 can be increased, so that the warm-up can be performed efficiently. On the other hand, the predetermined reference temperature Ta is preferably higher than the boiling point of air (about -190°C under atmospheric pressure) in order to suppress the generation of liquefied air in the compressor 30. Further, the predetermined reference temperature Ta is more preferably higher than the boiling point of oxygen (about -183°C under atmospheric pressure) in order to suppress the generation of liquefied oxygen in the compressor 30. Also, the predetermined reference temperature Ta is preferably higher than the lower limit value of the suction temperature at which the compressor 30 can operate in order to operate the compressor 30 normally. In the present embodiment, the predetermined reference temperature Ta is set to a temperature slightly higher than the lower limit value of the suction temperature at which the compressor 30 can operate.

[0047] A part of the gas discharged from the compressor 30 is heated by the second heater 32 and then returned to the tank 10A. Thereby, the tank 10A is warmed up. On the other hand, the rest of the gas discharged from the compressor 30 is supplied to the processing device 51 through the branch line 50 and processed by the processing device 51.

[0048] Referring to FIG. 2, as a result of the warm-up of the tank 10A, when the temperature in the tank 10A exceeds a predetermined temperature Tb, the warm-up of the tank 10B is started. The predetermined temperature Tb is a temperature near a predetermined reference temperature Ta. In the present embodiment, the predetermined temperature Tb is a temperature higher than the predetermined reference temperature Ta. In the present embodiment, when the temperature of the gas sucked into the compressor 30 using the gas taken out from the tank 10A cannot be maintained at the predetermined reference temperature Ta, the warm-up of the tank 10B is started. Even after the warm-up of the tank 10B is started, the warm-up of the tank 10A continues.

[0049] As shown in FIG. 4, in the warm-up of the tanks 10A and 10B, the control device 80 opens the first valve 60A, the second valve 61B, and the fifth valves 64A and 64B, and closes the first valves 60B and 60C, the second valves 61A and 61C, and the fifth valve 64C, and operates the compressor 30. Thereby, while gas is taken out from the tanks 10A and 10B to the circulation line 20, no gas is taken out from the tank 10C to the circulation line 20.

[0050] The gas taken out from the tank 10A is heated by the first heater 31 and supplied to the compressor 30. On the other hand, the gas taken out from the tank 10B passes through the bypass line 40B and is supplied to the compressor 30 without being heated by the first heater 31. That is, downstream of the first heater 31 and upstream of the compressor 30, the gas heated and temperature-raised by the first heater 31 and the gas not heated by the first heater 31 by bypassing the first heater 31 merge. Thereby, downstream of the first heater 31 and upstream of the compressor 30, the relatively high-temperature gas that has passed through the first heater 31 and the relatively low-temperature gas that has flowed through the bypass line 40B are mixed.

[0051] As the flow rate of gas passing through the first valve 60A increases, or as the flow rate of gas passing through the second valve 61B decreases, the flow rate of gas passing through the first heater 31 increases, while the flow rate of gas flowing through the bypass line 40A decreases. As a result, the temperature of the gas drawn into the compressor 30 increases as the flow rate of gas passing through the first valve 60A increases, or as the flow rate of gas passing through the second valve 61B decreases.

[0052] During the warm-up of tanks 10A and 10B, the opening of the first valve 60A and the opening of the second valve 61B are controlled so that the temperature of the gas drawn into the compressor 30 reaches a predetermined reference temperature Ta. Specifically, during the warm-up of tanks 10A and 10B, the control device 80 controls the opening of the first valve 60A and the opening of the second valve 61B so that the temperature measured by the second thermometer 72 reaches a predetermined reference temperature Ta.

[0053] A portion of the gas discharged from the compressor 30 is heated by the second heater 32 and then returned to tanks 10A and 10B. This warms up tanks 10A and 10B. Meanwhile, the remaining gas discharged from the compressor 30 is supplied to the processing unit 51 through the branch line 50 and processed in the processing unit 51.

[0054] Referring to Figure 2, when the temperature inside tank 10B exceeds a predetermined temperature Tb as a result of warming up tanks 10A and 10B, the warming up of tank 10C begins. In this embodiment, when it becomes impossible to maintain the temperature of the gas drawn into the compressor 30 using the gas extracted from tanks 10A and 10B at a predetermined reference temperature Ta, the warming up of tank 10C begins. Even after the warming up of tank 10C begins, the warming up of tanks 10A and 10B continues.

[0055] As shown in Figure 5, during the warm-up of tanks 10A to 10C, the control device 80 opens the first valves 60A and 60B, the second valve 61C, and the fifth valves 64A to 64C, while closing the first valve 60C and the second valves 61A and 61B, and operates the compressor 30. As a result, gas is drawn from tanks 10A to 10C into the circulation line 20.

[0056] The gas taken from tanks 10A and 10B is heated by the first heater 31 and supplied to the compressor 30, while the gas taken from tank 10C passes through the bypass line 40C and is supplied to the compressor 30 without being heated by the first heater 31. In other words, downstream of the first heater 31 and upstream of the compressor 30, the gas heated and warmed by the first heater 31 and the gas that bypasses the first heater 31 and is not heated by the first heater 31 merge. As a result, downstream of the first heater 31 and upstream of the compressor 30, the relatively high-temperature gas that has passed through the first heater 31 and the relatively low-temperature gas that has flowed through the bypass line 40C are mixed.

[0057] As the flow rate of gas passing through the first valves 60A and 60B increases, or as the flow rate of gas passing through the second valve 61C decreases, the flow rate of gas passing through the first heater 31 increases, while the flow rate of gas flowing through the bypass line 40C decreases. As a result, the temperature of the gas drawn into the compressor 30 increases as the flow rate of gas passing through the first valves 60A and 60B increases, or as the flow rate of gas passing through the second valve 61C decreases.

[0058] During the warm-up of tanks 10A to 10C, the opening degrees of the first valves 60A and 60B and the opening degree of the second valve 61C are controlled so that the temperature of the gas drawn into the compressor 30 reaches a predetermined reference temperature Ta. Specifically, during the warm-up of tanks 10A to 10C, the control device 80 controls the opening degrees of the first valves 60A and 60B and the opening degree of the second valve 61C so that the temperature measured by the second thermometer 72 reaches a predetermined reference temperature Ta.

[0059] A portion of the gas discharged from the compressor 30 is heated by the second heater 32 and then returned to tanks 10A to 10C. This warms up tanks 10A to 10C. Meanwhile, the remaining gas discharged from the compressor 30 is supplied to the processing unit 51 through the branch line 50 and processed in the processing unit 51.

[0060] As a result of warming up tanks 10A to 10C, when the temperature inside tank 10A reaches the target temperature Tg, the first valve 60A and the fifth valve 64A are closed from the state shown in Figure 5, and the warming up of tank 10A is terminated. Specifically, when the temperature measured by the first thermometer 70A reaches the target temperature Tg, the control device 80 controls the opening of the first valve 60A and the fifth valve 64A so that gas does not pass through them from the state shown in Figure 5. After that, the warming up of tanks 10B and 10C is continued.

[0061] After the warm-up of tank 10A is completed, the warm-up of tanks 10B and 10C is continued. As a result, when the temperature inside tank 10B reaches the target temperature Tg, the first valve 60B and the fifth valve 64B are closed, and the warm-up of tank 10B is terminated. Specifically, when the temperature measured by the first thermometer 70A reaches the target temperature Tg, the control device 80 controls the opening of the first valve 60B and the fifth valve 64B so that gas does not pass through them, as shown in Figure 6. After that, the warm-up of tank 10C is continued.

[0062] During the warm-up of tank 10C, as shown in Figure 6, the control device 80 opens the first valve 60C and the fifth valve 64C, and operates the compressor 30 with the first valves 60A, 60B, the second valves 61A to 61C, and the fifth valves 64A, 64B closed. As a result, gas is drawn from tank 10C into the circulation line 20, while no gas is drawn from tanks 10A and 10B into the circulation line 20. The gas drawn from tank 10C is heated by the first heater 31 and supplied to the compressor 30, where it is compressed. A portion of the gas discharged from the compressor 30 is heated by the second heater 32 and then returned to tank 10C. This warms up tank 10C. Meanwhile, the remaining gas discharged from the compressor 30 is supplied to the processing device 51 through the branch line 50 and processed by the processing device 51.

[0063] After the warm-up of tank 10B is completed, the warm-up of tank 10C is continued. As a result, when the temperature inside tank 10C reaches the target temperature Tg, the first valve 60C and the fifth valve 64C are closed, and the warm-up of tank 10C is terminated. Specifically, the control device 80 controls the opening of the first valve 60C and the fifth valve 64C so that gas does not pass through them. This terminates the warm-up process.

[0064] In all steps of the warm-up method according to this embodiment, the compressor 30 is controlled so that its discharge pressure reaches a target pressure value. In other words, the control device 80 performs pressure control to control the discharge pressure of the compressor 30 to a target pressure value. In this embodiment, the control device 80 controls the compressor 30 in pressure control so that its discharge pressure is higher than the pressure required for gas processing by the processing device 51.

[0065] In all steps of the warm-up method according to this embodiment, the opening degree of the third valve 62 and the opening degree of the fourth valve 63 are controlled according to the pressure in the tank 10 being warmed up. Specifically, the control device 80 controls the opening degree of the third valve 62 and the opening degree of the fourth valve 63 according to the pressure in the tank 10 being warmed up.

[0066] The control device 80 controls the opening of the third valve 62 to maximize the flow rate when the pressure in the warmed-up tank 10 is below a predetermined reference pressure. That is, the control device 80 fully opens the third valve 62. As a result, when the pressure downstream of the compressor 30 decreases, the control device 80 increases the discharge flow rate of the compressor 30 to control the pressure downstream of the compressor 30 to a target pressure value. The control device 80 also opens the fourth valve 63 to a predetermined opening when the pressure in the warmed-up tank 10 is below a predetermined reference pressure. The reference pressure is set to be below the upper limit of the allowable pressure of the tank 10.

[0067] When the pressure in the warmed-up tank 10 exceeds a predetermined reference pressure, the control device 80 controls the opening of the fourth valve 63 to increase the flow rate of gas passing through the fourth valve 63. This increases the amount of gas processed by the processing device 51 and decreases the flow rate of gas returning to the tank 10, thereby lowering the pressure in the tank 10. As a result, an excessive rise in pressure in the tank 10 can be suppressed.

[0068] If the flow rate of gas passing through the fourth valve 63 exceeds the maximum gas processing capacity of the processing device 51, but the pressure in the tank 10 does not fall below a predetermined reference pressure, the control device 80 controls the opening of the third valve 62 to reduce the flow rate of gas passing through the third valve 62. This increases the pressure downstream of the compressor 30. When the pressure downstream of the compressor 30 increases, the control device 80 controls the compressor 30 to reduce the discharge flow rate in order to control the pressure downstream of the compressor 30 to a pressure target value. As a result, the amount of heat input to the tank 10 decreases, and an excessive rise in the pressure inside the tank 10 is suppressed.

[0069] [Effects] The warm-up method for the ship 1 and tank according to this embodiment provides the following effects.

[0070] (1) The vessel 1 according to this embodiment includes: at least one tank 10 for storing cryogenic liquefied gas and gas generated by the vaporization of cryogenic liquefied gas; a circulation line 20 for returning the gas taken out from at least one tank 10 to at least one tank 10; a first heater 31 positioned on the circulation line 20 for heating the gas flowing through the circulation line 20; a positive displacement compressor 30 positioned on the circulation line 20 and downstream of the first heater 31 for compressing the gas flowing through the circulation line 20; and at least one bypass line 40 positioned corresponding to each of the at least one tank 10, for supplying gas from the corresponding tank 10 downstream of the first heater 31 and upstream of the compressor 30. The system includes a flow rate adjustment device (in this embodiment, including at least one first valve 60 and at least one second valve 61) that adjusts the flow rate of gas taken from at least one tank 10, flowing through a circulation line 20 and being heated by a first heater 31 before being supplied to the compressor 30, or the flow rate of gas taken from at least one tank 10 and flowing through a corresponding bypass line 40 before being supplied to the compressor 30.

[0071] Cryogenic liquefied gases, that is, liquefied gases with a boiling point of -183°C or lower at atmospheric pressure, generally have very small molecular weights, and the gas density of the gas generated when cryogenic liquefied gases vaporize is also generally very low. When a turbo-type compressor is used to return the gas taken out of tank 10 back to tank 10, if the gas density of the gas taken out of the tank is excessively low, sufficient discharge pressure may not be obtained to return the gas to tank 10. As a result, the time required for tank 10 to warm up may be extended. In contrast, according to the ship 1 of this embodiment, a positive displacement compressor 30 is used to return the gas taken out of tank 10 back to tank 10, so even if the gas density of the gas taken out of tank 10 is low, sufficient discharge pressure can be obtained to return the gas to tank 10. As a result, the time required for warm-up can be shortened.

[0072] The higher the gas density of the gas drawn into the compressor 30, that is, the lower the temperature of the gas drawn into the compressor 30, the greater the volumetric flow rate of the gas discharged from the compressor 30. Therefore, the lower the temperature of the gas drawn into the compressor 30, the more efficiently the tank 10 can be warmed up. According to the ship 1 of this embodiment, a portion of the gas taken out from the tank 10 passes through the bypass line 40 and is supplied to the compressor 30 without being heated by the first heater 31. Furthermore, the temperature of the gas drawn into the compressor 30 can be adjusted by changing the opening of the first valve 60 to adjust the flow rate of the gas heated by the first heater 31 and supplied to the compressor 30, and by changing the opening of the second valve 61 to adjust the flow rate of the gas supplied to the compressor 30 without being heated by the first heater 31. Therefore, by adjusting the temperature of the gas drawn into the compressor 30 to an appropriate temperature that takes into account the efficiency of warming up the tank 10, the time required for warming up can be shortened. For example, by adjusting the temperature of the gas drawn into the compressor 30 to the lowest possible temperature within the range of suction temperatures in which the compressor 30 can operate, the time required for the tank 10 to warm up can be shortened.

[0073] (2) In this embodiment, the vessel 1 further comprises a second thermometer 72 located downstream of the first heater 31 and upstream of the compressor 30 in the circulation line 20 for measuring the temperature of the gas drawn into the compressor 30, and a control device 80 for controlling a flow rate adjustment device (in this embodiment, including at least one first valve 60 and at least one second valve 61), the control device 80 controlling the flow rate adjustment device so that the temperature of the gas measured by the second thermometer 72 is maintained at a predetermined reference temperature Ta.

[0074] According to the vessel 1 of this embodiment, the time required for the tank 10 to warm up can be shortened by setting the reference temperature Ta to an appropriate temperature that takes into account the efficiency of warming up the tank 10, for example, the lowest possible temperature within the range of suction temperatures in which the compressor 30 can operate.

[0075] (3) In this embodiment, the reference temperature Ta is higher than the lower limit of the suction temperature at which the compressor 30 can operate.

[0076] According to the vessel 1 of this embodiment, it is possible to prevent the temperature of the gas drawn into the compressor 30 from falling below the lower limit of the compressor 30's operating suction temperature. As a result, efficient warm-up of the tank 10 can be achieved while the compressor 30 operates normally.

[0077] (4) In this embodiment, the reference temperature Ta is higher than the boiling point of air or oxygen.

[0078] When the gas is at an extremely low temperature, liquefied air or liquefied oxygen may be generated in the compressor 30 when it compresses the gas, which can adversely affect the compressor 30. According to the ship 1 of this embodiment, it is possible to suppress the temperature of the gas drawn into the compressor 30 from falling below the boiling point of air or oxygen. As a result, it is possible to suppress the generation of liquefied air or liquefied oxygen in the compressor 30.

[0079] (5) At least one tank 10 includes tank 10A and tank 10B, and the flow rate adjustment device comprises at least one first valve 60 located on the circulation line 20 and upstream of the first heater 31, corresponding to at least one tank 10, and adjusting the flow rate of gas supplied from the corresponding tank 10 to the first heater 31, and at least one second valve 61 located on at least one bypass line 40, corresponding to at least one bypass line 40, and adjusting the flow rate of gas flowing through the corresponding bypass line 40, and the control device 80 warms up tank 10A by opening the first valve 60A corresponding to tank 10A, while closing the first valve 60B and the second valve 61B corresponding to tank 10B, and heating and compressing the gas taken from tank 10A and returning it to tank 10A, When tank 10A has warmed up and the temperature of the gas in tank 10A exceeds a predetermined temperature Tb, the compressor 30, the opening of at least one first valve 60, and the opening of at least one second valve 61 are controlled to warm up tanks 10A and 10B by opening the second valve 61B corresponding to tank 10B, heating and compressing the gas taken out from tanks 10A and 10B, and returning it to tanks 10A and 10B.

[0080] According to the vessel 1 of this embodiment, when the warm-up of tank 10A progresses and the temperature of the gas in tank 10A exceeds a predetermined temperature Tb, cryogenic gas is supplied from tank 10B, which has not yet been warmed up, to the upstream of the compressor 30. As a result, even if the temperature of the gas drawn into the compressor 30 cannot be maintained at a predetermined reference temperature Ta using only the gas taken from tank 10A, the temperature of the gas drawn into the compressor 30 can be maintained at the reference temperature Ta by using the cryogenic gas taken from tank 10B. Consequently, the time required for the warm-up of tank 10 can be shortened.

[0081] (6) The vessel 1 according to this embodiment includes a third valve 62 located on the circulation line 20 and downstream of the compressor 30, which can adjust the flow rate by changing its opening, and a control device 80 that controls the compressor 30 to control the discharge pressure of the compressor 30 to a target pressure value, wherein the control device 80 controls the flow rate through the third valve 62 in the pressure control.

[0082] According to the vessel 1 of this embodiment, the time required for the tank 10 to warm up can be shortened. When the flow rate through the third valve 62 located downstream of the compressor 30 is controlled to increase in the pressure control, the pressure downstream of the compressor 30 decreases. At this time, the control device 80 increases the discharge flow rate of the compressor 30 to control the discharge pressure to the pressure target value. As a result, the amount of heat supplied to the tank 10 can be increased, and the time required for the tank 10 to warm up can be shortened.

[0083] (7) The vessel 1 according to this embodiment includes at least one first pressure gauge 71, each corresponding to at least one tank 10, for measuring the pressure of the corresponding tank 10; a branch line 50 that branches off from the circulation line 20 downstream of the compressor 30; and a gas processing device 51 that is fluidly connected to the branch line 50 and processes the gas. The control device 80 increases the flow rate of gas sent to the gas processing device 51 when the pressure of at least one tank 10 exceeds a predetermined reference pressure.

[0084] During the warm-up of tank 10, when heated gas is returned to tank 10, the pressure inside tank 10 rises. Therefore, in order to lower the pressure inside tank 10 so that it does not exceed the allowable pressure of tank 10, it is necessary to discharge a portion of the gas inside tank 10 (hereinafter sometimes referred to as excess gas) from tank 10. According to the ship 1 of this embodiment, when the pressure inside tank 10 exceeds a predetermined reference pressure, the flow rate of excess gas sent to the treatment device 51 increases, thereby reducing the flow rate of gas returned to tank 10. This makes it possible to efficiently warm up tank 10 while suppressing the rise in pressure inside tank 10.

[0085] (8) In this embodiment, in pressure control, the control device 80 increases the flow rate of gas sent to the processing device 51, and when the pressure in at least one tank 10 exceeds a predetermined reference pressure, it controls the opening degree of the third valve 62 to reduce the flow rate passing through the third valve 62.

[0086] According to the vessel 1 of this embodiment, when the pressure in the tank 10 exceeds a predetermined reference pressure again after increasing the flow rate of excess gas processed by the treatment device 51, the flow rate through the third valve 62 is reduced, thereby increasing the pressure downstream of the compressor 30. As a result, the load on the compressor 30 decreases, the discharge flow rate decreases, and the amount of heat input to the tank 10 decreases, thus suppressing a further increase in the pressure in the tank 10. As a result, the tank 10 can be efficiently warmed up while suppressing the rise in pressure inside the tank 10.

[0087] (9) In this embodiment, the cryogenic liquefied gas is liquefied hydrogen.

[0088] The present disclosure can be suitably implemented according to the vessel 1 of this embodiment.

[0089] (10) The method according to this embodiment is a method for warming up at least one tank 10 that stores cryogenic liquefied gas and gas generated by the vaporization of cryogenic liquefied gas, comprising heating a portion of the gas taken out from at least one tank 10, combining the heated gas and the unheated gas and then pressurizing it, and returning the pressurized gas to the tank 10, wherein the flow rate of the heated gas and the flow rate of the unheated gas are adjusted so that the temperature of the gas before pressurization is maintained at a predetermined reference temperature Ta.

[0090] According to the method of this embodiment, the flow rate of the gas to be heated and the flow rate of the gas not to be heated among the gas taken out of the tank 10 are adjusted so that the temperature of the gas before pressurization is maintained at a predetermined reference temperature Ta. For this reason, when a compressor 30 is used to pressurize the gas, the time required for warm-up can be shortened by adjusting the temperature of the gas drawn into the compressor 30 to an appropriate temperature that takes into account the warm-up efficiency of the tank 10. For example, the time required for warm-up of the tank 10 can be shortened by adjusting the temperature of the gas drawn into the compressor 30 to the lowest possible temperature within the range of intake temperatures in which the compressor 30 can operate.

[0091] [Modifications] This disclosure is not limited to the configurations described in the embodiments above, and various modifications are possible.

[0092] In the above embodiment, the warm-up of tanks 10A to 10C was started sequentially, but as shown in the modified embodiment in Figure 7, the warm-up of tanks 10A to 10C may be started simultaneously and performed in parallel. In this case, a portion of the gas taken from tanks 10A to 10C flows through at least one of the bypass lines 40A to 40C and is supplied to the compressor 30 without being heated by the first heater 31.

[0093] [Other Modifications] In the above embodiment, liquefied hydrogen was given as an example of a cryogenic liquefied gas, but the cryogenic liquefied gas according to this disclosure is not limited to liquefied hydrogen, and may be other liquefied gases such as liquefied helium or liquefied nitrogen.

[0094] In the above embodiment, an example was described in which the tank 10 is a cargo tank, but the tank 10 may also be a fuel tank that contains liquefied hydrogen as fuel.

[0095] In the above embodiment, the vessel 1 was equipped with three tanks 10A to 10C, but the number of tanks according to the present disclosure is not limited thereto. The number of tanks according to the present disclosure may be one, two, or four or more.

[0096] In the above embodiment, the processing device 51 was a gas combustion unit, but it may be another processing device such as a boiler.

[0097] In the above embodiment, the control of the components of the ship 1 (first to fifth valves 60 to 64, compressor 30, first heater 31, and second heater 32) in the tank warm-up method was described with specific examples, but the control in the tank warm-up method according to this disclosure is not limited to these specific examples. The control of the ship's components in the tank warm-up method can be modified as appropriate, insofar as it has the function of adjusting the temperature of the gas drawn into the compressor to shorten the time required for tank warm-up.

[0098] In the above embodiment, an example was described in which the flow rate control device according to the Disclosure includes a first valve 60 and a second valve 61. However, the flow rate control device according to the Disclosure may include only one of the first valve 60 or the second valve 61. Furthermore, instead of the first valve 60 and the second valve 61, the flow rate control device according to the Disclosure may include a valve (for example, a three-way valve) that adjusts both the flow rate of gas supplied from the tank 10 to the first heater 31 and the flow rate of gas flowing from the tank 10 to the corresponding bypass line 40.

[0099] In the above embodiment, the flow rate of excess gas sent to the processing device 51 was adjusted by increasing the flow rate through the fourth valve 63. However, the flow rate of excess gas sent to the processing device 51 may also be adjusted by adjusting the load factor (gas processing amount) of the processing device 51.

[0100] [Note] The ship and tank warming method relating to this disclosure provides the following embodiments.

[0101] [Aspect 1] A ship comprising: at least one tank for storing cryogenic liquefied gas and gas generated by the vaporization of cryogenic liquefied gas; a circulation line for returning the gas taken from the at least one tank to the at least one tank; a heater disposed on the circulation line for heating the gas flowing through the circulation line; a positive displacement compressor disposed on the circulation line and downstream of the heater for compressing the gas flowing through the circulation line; at least one bypass line, each corresponding to the at least one tank, for supplying gas from the corresponding tank downstream of the heater and upstream of the compressor; and a flow rate adjustment device for adjusting the flow rate of gas taken from the at least one tank, flowing through the circulation line and heated by the heater before being supplied to the compressor, or the flow rate of gas taken from the at least one tank and flowing through the corresponding bypass line and supplied to the compressor.

[0102] [Aspect 2] The vessel according to aspect 1, further comprising a thermometer positioned downstream of the heater and upstream of the compressor in the circulation line for measuring the temperature of the gas drawn into the compressor, and a control device for controlling the flow rate adjustment device, wherein the control device controls the flow rate adjustment device so that the temperature of the gas measured by the thermometer is maintained at a predetermined reference temperature.

[0103] [Aspect 3] The vessel according to aspect 2, wherein the reference temperature is higher than the lower limit temperature of the suction temperature at which the compressor can operate.

[0104] [Aspect 4] The vessel according to aspect 2 or 3, wherein the reference temperature is higher than the boiling point of air or oxygen.

[0105] [Aspect 5] The at least one tank includes a first tank and a second tank, and the flow rate adjustment device comprises at least one first valve, each located on the circulation line and upstream of the heater and corresponding to the at least one tank, for adjusting the flow rate of gas supplied from the corresponding tank to the heater, and at least one second valve, each located on the at least one bypass line and corresponding to the flow rate of gas flowing through the corresponding bypass line, and the control device warms up the first tank by opening the first valve corresponding to the first tank, while closing the first and second valves corresponding to the second tank, and heating and compressing the gas taken from the first tank and returning it to the first tank. A ship according to any one of embodiments 2 to 4, wherein when the temperature of the gas in the first tank exceeds a predetermined temperature as a result of the first tank being warmed up, the compressor, the opening degree of at least one first valve, and the opening degree of at least one second valve are controlled to warm up the first tank and the second tank by opening a second valve corresponding to the second tank, heating and compressing the gas taken out from the first tank and the second tank, and returning it to the first tank and the second tank.

[0106] [Aspect 6] A vessel according to any one of aspects 1 to 5, comprising: a third valve located on the circulation line and downstream of the compressor, the flow rate through which the valve passes can be adjusted by changing the degree of opening; and a control device that controls the compressor to control the discharge pressure of the compressor to a pressure target value, wherein the control device controls the flow rate through the third valve in the pressure control.

[0107] [Aspect 7] The vessel according to aspect 6, comprising: at least one pressure gauge arranged corresponding to each of the at least one tank for measuring the pressure of the corresponding tank; a branch line branching off from the circulation line downstream of the compressor and upstream of the third valve; and a gas processing device fluidly connected to the branch line for processing the gas, wherein the control device controls the opening of the third valve in the pressure control to maintain the flow rate through the third valve when the pressure measured by the at least one pressure gauge is within a predetermined reference pressure, and increases the flow rate of the gas sent to the gas processing device when the pressure of the at least one tank exceeds the predetermined reference pressure.

[0108] [Aspect 8] The ship according to aspect 7, wherein the control device, in the pressure control, after increasing the flow rate of gas sent to the processing device, controls the opening of the third valve to reduce the flow rate through the third valve when the pressure in at least one tank exceeds the predetermined reference pressure.

[0109] [Aspect 9] The vessel according to any one of aspects 1 to 8, wherein the cryogenic liquefied gas is liquefied hydrogen.

[0110] [Aspect 10] A method for warming up at least one tank for storing cryogenic liquefied gas and gas generated by the vaporization of cryogenic liquefied gas, comprising: heating a portion of the gas taken out from the at least one tank; combining the heated gas and the unheated gas and then pressurizing the mixture; and returning the pressurized gas to the tank, wherein the flow rates of the heated gas and the unheated gas are adjusted so that the temperature of the gas before pressurization is maintained at a predetermined reference temperature.

Claims

1. A ship comprising: at least one tank for storing cryogenic liquefied gas and gas generated by the vaporization of cryogenic liquefied gas; a circulation line for returning gas taken from the at least one tank to the at least one tank; a heater disposed on the circulation line for heating the gas flowing through the circulation line; a positive displacement compressor disposed on the circulation line and downstream of the heater for compressing the gas flowing through the circulation line; at least one bypass line, each corresponding to the at least one tank, for supplying gas from the corresponding tank downstream of the heater and upstream of the compressor; and a flow rate adjustment device for adjusting the flow rate of gas taken from the at least one tank, flowing through the circulation line and heated by the heater before being supplied to the compressor, or the flow rate of gas taken from the at least one tank and flowing through the corresponding bypass line and supplied to the compressor.

2. The vessel according to claim 1, further comprising: a thermometer positioned downstream of the heater and upstream of the compressor in the circulation line for measuring the temperature of the gas drawn into the compressor; and a control device for controlling the flow rate adjustment device, wherein the control device controls the flow rate adjustment device so that the temperature of the gas measured by the thermometer is maintained at a predetermined reference temperature.

3. The vessel according to claim 2, wherein the reference temperature is higher than the lower limit temperature of the suction temperature at which the compressor can operate.

4. The vessel according to claim 2, wherein the reference temperature is higher than the boiling point of air or oxygen.

5. The at least one tank includes a first tank and a second tank, and the flow rate adjustment device comprises at least one first valve, each located on the circulation line and upstream of the heater, corresponding to the at least one tank, and adjusting the flow rate of gas supplied from the corresponding tank to the heater, and at least one second valve, each located on the at least one bypass line, and adjusting the flow rate of gas flowing through the corresponding bypass line, and the control device warms up the first tank by opening the first valve corresponding to the first tank, while closing the first and second valves corresponding to the second tank, and heating and compressing the gas taken from the first tank and returning it to the first tank, The ship according to claim 2, wherein when the temperature of the gas in the first tank exceeds a predetermined temperature as a result of the first tank being warmed up, the compressor, the opening degree of the at least one first valve, and the opening degree of the at least one second valve are controlled to warm up the first tank and the second tank by opening the second valve corresponding to the second tank, heating and compressing the gas taken out from the first tank and the second tank, and returning it to the first tank and the second tank.

6. The vessel according to claim 1, further comprising: a third valve located on the circulation line and downstream of the compressor, the flow rate through which the valve passes can be adjusted by changing the degree of opening; and a control device that controls the compressor to control the discharge pressure of the compressor to a target pressure value, wherein the control device controls the flow rate through the third valve in the pressure control.

7. The vessel according to claim 6, comprising: at least one pressure gauge arranged corresponding to each of the at least one tanks for measuring the pressure of the corresponding tank; a branch line branching off from the circulation line downstream of the compressor and upstream of the third valve; and a gas treatment device fluidly connected to the branch line for processing the gas, wherein the control device controls the opening of the third valve to maintain the flow rate through the third valve when the pressure measured by the at least one pressure gauge is within a predetermined reference pressure, and increases the flow rate of the gas sent to the gas treatment device when the pressure of the at least one tank exceeds the predetermined reference pressure.

8. The vessel according to claim 7, wherein the control device, in the pressure control, after increasing the flow rate of gas supplied to the processing device, controls the opening of the third valve to reduce the flow rate through the third valve when the pressure in at least one tank exceeds the predetermined reference pressure.

9. The vessel according to claim 1, wherein the cryogenic liquefied gas is liquefied hydrogen.

10. A method for warming up at least one tank for storing cryogenic liquefied gas and gas generated by the vaporization of cryogenic liquefied gas, comprising: heating a portion of the gas taken out of the at least one tank; combining the heated gas and the unheated gas and pressurizing the mixture; and returning the pressurized gas to the tank, wherein the flow rates of the heated gas and the unheated gas are adjusted so that the temperature of the gas before pressurization is maintained at a predetermined reference temperature.

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