Cooling method of pump device

Abstract

According to the method, liquefied gas is simultaneously introduced into suction containers (2A, 2B) through introduction lines (121, 122) extending from a liquefied gas storage tank (105), and the liquefied gas passes through a flow path switching device (5A) in the suction container (2A) while bypassing a submersible pump (1A) in the suction container (2A), and passes through a submersible pump (1B) in the suction container (2B) while bypassing a flow path switching device (5A) in the suction container (2A). Liquefied gas passes through a flow path switching device (5B) in a suction container (2B), and the liquefied gas is discharged from a suction container (2A) and a suction container (2B) through a flow path switching device (5A) and a flow path switching device (5B).

Description

Technical Field

[0001] This invention relates to a cooling method for submersible pumps used for conveying liquefied gases such as liquid hydrogen, liquid nitrogen, liquid ammonia, liquefied natural gas, liquefied ethylene gas, and liquefied petroleum gas, and particularly to a technology for preventing the impeller of a submersible pump from rotating and for cooling the submersible pump when it is stopped. Background Technology

[0002] Natural gas is widely used in thermal power generation and as a chemical feedstock. Additionally, hydrogen is anticipated as an energy source that does not produce carbon dioxide, a major contributor to global warming. Applications of hydrogen as an energy source include fuel cells and turbine power generation. Since natural gas and hydrogen are in a gaseous state at room temperature, they are cooled and liquefied for storage and transportation. Liquefied natural gas (LNG), liquid hydrogen, and other liquefied gases are temporarily stored in liquefied gas storage tanks and then pumped to power plants, factories, and other facilities.

[0003] Figure 41 This is a schematic diagram illustrating a conventional example of a pump device for drawing liquefied gas. Pump 500 is disposed within a longitudinal suction container 505 connected to a liquefied gas storage tank (not shown) containing the liquefied gas. The liquefied gas is introduced into the suction container 505 through suction port 501, filling the suction container 505. The entire pump 500 is immersed in the liquefied gas. Therefore, pump 500 is a submersible pump capable of operating in liquefied gas. When pump 500 is operating, the liquefied gas is discharged through pump 500 via discharge port 502. During the operation of pump 500, a portion of the liquefied gas within suction container 505 vaporizes into gas, which is discharged from suction container 505 through exhaust line 503.

[0004] When pump 500 is started, if pump 500 is at room temperature, the liquefied gas will vaporize when it comes into contact with the cryogenic liquefied gas. Therefore, in order to prevent the liquefied gas from vaporizing, pump 500 is cooled by liquefied gas before it is started.

[0005] Cooling is achieved by injecting liquefied gas (e.g., liquefied natural gas) into the suction container 505. The liquefied gas injected into the suction container 505 fills the suction container 505, flows into the pump 500 from the suction port 500a, and is discharged through the discharge port 502.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Utility Model Application Publication No. 59-159795

[0009] Patent Document 2: Japanese Published Patent No. 62-031680 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] In order to pressurize liquefied gas to the pressure required on the demand side, such as Figure 42 As shown, sometimes multiple pump units are connected in series. The liquefied gas is pressurized sequentially by pump 500 of the multiple pump units.

[0012] However, when cooling a series-connected pump unit as described above, the following problem arises. Specifically, when liquefied gas is introduced into the pump unit before operation begins, the liquefied gas flows throughout the entire pump 500. This flow of liquefied gas forces the impeller of the pump 500, which is not currently in operation, to rotate. As a result, sliding parts such as bearings may be damaged. To prevent accidental rotation of the impeller of the pump 500, it is also considered to flow the liquefied gas at a low flow rate, but in this case, it takes a very long time for the entire pump unit to complete cooling.

[0013] Therefore, the present invention provides a method for preventing the impeller of a submersible pump from rotating during operation and for performing cooling on the submersible pump.

[0014] Methods for solving problems

[0015] One aspect provides a cooling method in which a liquefied gas is used to cool a plurality of submersible pumps comprising at least a first pump assembly and a second pump assembly interconnected with each other. In the cooling method, the liquefied gas is simultaneously introduced into a first suction container of the first pump assembly and a second suction container of the second pump assembly via a first inlet line and a second inlet line extending from a liquefied gas storage tank. The liquefied gas bypasses the first submersible pump in the first suction container while passing through a first flow path switching device in the first suction container, and bypasses the second submersible pump in the second suction container while passing through a second flow path switching device in the second suction container. The liquefied gas is then discharged from the first suction container and the second suction container via the first flow path switching device and the second flow path switching device.

[0016] In one aspect, the first flow path switching device and the second flow path switching device each include: a flow path structure having a pump-side flow path, a container-side flow path, and an outlet flow path; and a valve core disposed within the flow path structure, selectively connecting the outlet flow path to either the pump-side flow path or the container-side flow path, wherein the pump-side flow path is connected to the outlet of the corresponding submersible pump, the container-side flow path is connected to the interior of the corresponding suction container, and the outlet flow path is connected to the discharge port of the corresponding suction container.

[0017] In one aspect, the first flow path switching device and the second flow path switching device each further include a spring for pressing the valve core against the flow path structure to close the pump-side flow path.

[0018] In one aspect, the liquefied gas is simultaneously introduced into the first and second inlet containers via the first and second inlet lines and through the discharge ports of the first and second inlet containers.

[0019] In one aspect, the liquefied gas is simultaneously introduced into the first and second inhalation containers via the first and second inhalation lines and through the inhalation ports of the first and second inhalation containers.

[0020] In one aspect, the first pump device is connected in series with the second pump device.

[0021] In one aspect, the first pump device and the second pump device are connected in parallel.

[0022] One aspect provides a cooling method that uses liquefied gas to cool multiple submersible pumps of multiple pump devices, including at least a first pump device and a second pump device interconnected. In this cooling method, liquefied gas is introduced into a first suction container of the first pump device, while evaporating gas generated from the liquefied gas bypasses the first submersible pump in the first suction container, and the evaporating gas is introduced from the first suction container into a second suction container of the second pump device through a first flow path switching device in the first suction container. The first submersible pump is then started to operate, introducing liquefied gas from the first suction container into the second suction container, while the liquefied gas bypasses the second submersible pump in the second suction container, and the liquefied gas is introduced through a second flow path switching device in the second suction container.

[0023] In one aspect, the first flow path switching device and the second flow path switching device each include: a flow path structure having a pump-side flow path, a container-side flow path, and an outlet flow path; and a valve core disposed within the flow path structure, selectively connecting the outlet flow path to either the pump-side flow path or the container-side flow path, wherein the pump-side flow path is connected to the outlet of the corresponding submersible pump, the container-side flow path is connected to the interior of the corresponding suction container, and the outlet flow path is connected to the discharge port of the corresponding suction container.

[0024] In one aspect, the first flow path switching device and the second flow path switching device each further include a spring for pressing the valve core against the flow path structure to close the pump-side flow path.

[0025] In one aspect, the liquefied gas is introduced from the first intake container into the second intake container through the discharge port of the second intake container by starting the operation of the first submersible pump.

[0026] In one aspect, the liquefied gas is introduced from the first suction container into the second suction container through the suction port of the second suction container by starting the operation of the first submersible pump.

[0027] In one aspect, the plurality of pump devices further includes a third pump device connected to the first pump device and the second pump device, the third pump device having the same configuration as the first pump device and the second pump device. In the method, the evaporated gas is introduced from the second suction container into the third suction container of the third pump device. After the first submersible pump is started, the liquefied gas is introduced from the second suction container into the third suction container, while the liquefied gas bypasses the third submersible pump in the third suction container and passes through a third flow path switching device in the third suction container.

[0028] In one aspect, the first pump device, the second pump device, and the third pump device are connected in series.

[0029] In one aspect, the first pump device, the second pump device, and the third pump device are connected in parallel.

[0030] In one aspect, the plurality of pump devices further includes a third pump device connected to the first pump device and the second pump device, the third pump device having the same configuration as the first pump device and the second pump device. The method further includes a process of simultaneously introducing the evaporated gas from the first intake container into the second intake container of the second pump device and the third intake container of the third pump device, starting the operation of the first submersible pump, simultaneously introducing liquefied gas from the first intake container into the second intake container and the third intake container, while allowing the liquefied gas to bypass the second submersible pump and pass through the second flow path switching device, and while allowing the liquefied gas to bypass the third submersible pump in the third intake container and pass through the third flow path switching device in the third intake container, and simultaneously discharging the liquefied gas from the second intake container and the third intake container through the second flow path switching device and the third flow path switching device.

[0031] In one aspect, the first pump device, the second pump device, and the third pump device are connected in series.

[0032] In one aspect, the first pump device, the second pump device, and the third pump device are connected in parallel.

[0033] In one aspect, the first pump device is connected in series with the second pump device.

[0034] In one aspect, the first pump device and the second pump device are connected in parallel.

[0035] Invention Effects

[0036] The flow path switching device prevents liquefied gas introduced into the suction container during cooling from passing through the submersible pump. Therefore, the impeller of the submersible pump will not rotate when it is stopped, thus preventing damage to the sliding parts such as the bearings. Attached Figure Description

[0037] Figure 1 This is a diagram illustrating one embodiment of a pump device for conveying liquefied gas.

[0038] Figure 2 This is a cross-sectional view showing one embodiment of the detailed configuration of the flow path switching device.

[0039] Figure 3 This shows the status of the flow path switching device when the submersible pump is running.

[0040] Figure 4 This is a diagram illustrating one implementation method of cooling.

[0041] Figure 5 This is a diagram used to illustrate other embodiments of cooling.

[0042] Figure 6 This is a schematic diagram illustrating one embodiment of a pump system having multiple pump devices connected in series.

[0043] Figure 7 It shows the... Figure 6 A diagram illustrating one embodiment of cooling using multiple submersible pumps.

[0044] Figure 8 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units connected in series.

[0045] Figure 9 It shows the... Figure 8 A diagram illustrating one embodiment of cooling using multiple submersible pumps.

[0046] Figure 10 This is a schematic diagram illustrating one embodiment of cooling a pump system having multiple pump units connected in series and parallel.

[0047] Figure 11 This is a schematic diagram illustrating another implementation of cooling for a pump system having multiple pump units connected in series and parallel.

[0048] Figure 12 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units connected in series.

[0049] Figure 13 It shows that it is aimed at Figure 12 The diagram shows one implementation of a pump system for cooling.

[0050] Figure 14 It shows that it is aimed at Figure 12 The diagram shows one implementation of a pump system for cooling.

[0051] Figure 15 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units connected in series.

[0052] Figure 16 It shows that it is aimed at Figure 15 The diagram shows one implementation of a pump system for cooling.

[0053] Figure 17 It shows that it is aimed at Figure 15 The diagram shows one implementation of a pump system for cooling.

[0054] Figure 18 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units connected in series.

[0055] Figure 19 It shows that it is aimed at Figure 18 The diagram shows one implementation of a pump system for cooling.

[0056] Figure 20 It shows that it is aimed at Figure 18 The diagram shows one implementation of a pump system for cooling.

[0057] Figure 21 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units connected in series.

[0058] Figure 22 It shows that it is aimed at Figure 21 The diagram shows one implementation of a pump system for cooling.

[0059] Figure 23 It shows that it is aimed at Figure 21 The diagram shows one implementation of a pump system for cooling.

[0060] Figure 24 This is a schematic diagram illustrating one embodiment of a pump system having multiple pump devices connected in series and parallel.

[0061] Figure 25 It shows that it is aimed at Figure 24 The diagram shows one implementation of a pump system for cooling.

[0062] Figure 26 It shows that it is aimed at Figure 24 The diagram shows one implementation of a pump system for cooling.

[0063] Figure 27 This is a schematic diagram illustrating one embodiment of a pump system having multiple pump devices connected in parallel.

[0064] Figure 28 It shows that it is aimed at Figure 27 The diagram shows one implementation of a pump system for cooling.

[0065] Figure 29 It shows that it is aimed at Figure 27 The diagram shows one implementation of a pump system for cooling.

[0066] Figure 30 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump devices connected in parallel.

[0067] Figure 31 It shows that it is aimed at Figure 30 The diagram shows one implementation of a pump system for cooling.

[0068] Figure 32 It shows that it is aimed at Figure 30 The diagram shows one implementation of a pump system for cooling.

[0069] Figure 33 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units connected in parallel.

[0070] Figure 34 It shows that it is aimed at Figure 33 The diagram shows one implementation of a pump system for cooling.

[0071] Figure 35 It shows that it is aimed at Figure 33 The diagram shows one implementation of a pump system for cooling.

[0072] Figure 36 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units connected in parallel.

[0073] Figure 37 It shows that it is aimed at Figure 36 The diagram shows one implementation of a pump system for cooling.

[0074] Figure 38 It shows that it is aimed at Figure 36 The diagram shows one implementation of a pump system for cooling.

[0075] Figure 39 This is a cross-sectional view illustrating another embodiment of the flow path switching device.

[0076] Figure 40 This is a cross-sectional view showing another embodiment of the flow path switching device.

[0077] Figure 41 This is a schematic diagram illustrating an existing example of a pump device used to draw liquefied gas.

[0078] Figure 42 This is a schematic diagram illustrating an example of multiple pump units connected in series. Detailed Implementation

[0079] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a diagram illustrating one embodiment of a pump device for conveying liquefied gas. As a result... Figure 1 Examples of liquefied gases transported by the pump device 100 shown include liquid hydrogen, liquid nitrogen, liquid ammonia, liquefied natural gas, liquefied ethylene gas, and liquefied petroleum gas.

[0080] like Figure 1 As shown, the pump assembly 100 includes a submersible pump 1 for conveying liquefied gas, a suction container 2 internally housing the submersible pump 1, and a flow path switching device 5 for preventing rotation of the impeller 15 of the submersible pump 1 during operation stoppage. The suction container 2 has a suction port 7 and a discharge port 8. Liquefied gas is introduced into the suction container 2 through the suction port 7, and the suction container 2 is filled with liquefied gas. During operation of the submersible pump 1, the entire submersible pump 1 is immersed in the liquefied gas. Therefore, the submersible pump 1 is configured to operate in liquefied gas.

[0081] The submersible pump 1 includes a motor 11 comprising a motor rotor 9 and a motor stator 10, a rotating shaft 12 connected to the motor 11, a plurality of bearings 14 rotatably supporting the rotating shaft 12, an impeller 15 fixed to the rotating shaft 12, and a pump housing 16 housing the impeller 15. A flow path switching device 5 is disposed within the suction container 2. More specifically, the flow path switching device 5 is connected to both the discharge port 4 of the submersible pump 1 and the discharge port 8 of the suction container 2. The specific configuration of the flow path switching device 5 will be described later.

[0082] The motor rotor 9 and motor stator 10 are housed within the motor housing 13. When power is supplied to the motor 11 via a power cable (not shown), the motor 11 causes the rotating shaft 12 and impeller 15 to rotate as a unit. Along with the rotation of the impeller 15, liquefied gas is drawn into the submersible pump 1 from the suction port 3 and discharged into the flow path switching device 5 through the discharge path 17 and the discharge port 4. Furthermore, the liquefied gas passes through the flow path switching device 5 and is discharged through the discharge port 8 of the suction container 2.

[0083] A suction valve 22 is connected to the suction port 7, and a discharge valve 23 is connected to the discharge port 8. The suction container 2 has a discharge port 25 connected to its bottom. A discharge valve 26 is connected to the discharge port 25. The suction port 7 is located on the side wall of the suction container 2, at a position higher than the bottom of the suction container 2. The discharge port 8 is located on the upper part of the suction container 2, at a position higher than the suction port 7. During operation of the submersible pump 1, the suction valve 22 and the discharge valve 23 are open, and the discharge valve 26 is closed.

[0084] An exhaust line 31 is connected to the upper part of the suction container 2. During the operation of the submersible pump 1, a portion of the liquefied gas is vaporized into gas due to the heat generated by the submersible pump 1, and this gas is discharged from the suction container 2 through the exhaust line 31. A vent valve 32 is connected to the exhaust line 31. In one embodiment, the gas may also be guided to a gas processing device (not shown) through the exhaust line 31. A gas processing device is a device for processing the gas (e.g., natural gas or hydrogen) obtained from the vaporization of liquefied gas. Examples of gas processing devices include gas combustion devices, chemical gas processing devices, and gas adsorption devices.

[0085] Figure 2 This is a cross-sectional view showing one embodiment of the detailed configuration of the flow path switching device 5. (See attached image.) Figure 2As shown, the flow path switching device 5 includes a flow path structure 45 having a pump-side flow path 41, a container-side flow path 42, and an outlet flow path 43, and a valve core 47 disposed within the flow path structure 45. The pump-side flow path 41 communicates with the outlet 4 of the submersible pump 1, the container-side flow path 42 communicates with the interior of the suction container 2, and the outlet flow path 43 communicates with the discharge port 8 of the suction container 2. The valve core 47 is configured to selectively connect the outlet flow path 43 to either the pump-side flow path 41 or the container-side flow path 42. The configuration of the flow path switching device 5 is not limited to any particular configuration, as long as it performs its desired function. Figure 2 The implementation method shown.

[0086] Figure 2 The diagram shows the state of the flow path switching device 5 when the submersible pump 1 is not in operation. The valve core 47 is pressed against the flow path structure 45 by a spring 50, closing the pump-side flow path 41. More specifically, the flow path structure 45 has a valve seat 51 formed around the outlet of the pump-side flow path 41, against which the valve core 47 is pressed by the spring 50. Therefore, while the valve core 47 is pressed against the valve seat 51, the pump-side flow path 41 is closed, and the container-side flow path 42 communicates with the outflow flow path 43. The container-side flow path 42 opens inside the suction container 2 and communicates with the suction port 7 through the interior of the suction container 2.

[0087] Figure 3 The state of the flow path switching device 5 is shown when the submersible pump 1 is operating. When the submersible pump 1 is operating, liquefied gas is discharged from the outlet 4 of the submersible pump 1 and flows into the pump-side flow path 41 of the flow path switching device 5. The liquefied gas flowing in the pump-side flow path 41 resists the force of the spring 50, causing the valve core 47 to move, opening the pump-side flow path 41 and closing the container-side flow path 42 with the valve core 47. As a result, the pump-side flow path 41 is connected to the outflow flow path 43.

[0088] When the submersible pump 1 stops operating, the valve core 47 is pressed against the valve seat 51 by the spring 50. As a result, as... Figure 2 As shown, the pump-side flow path 41 is closed, and the container-side flow path 42 is connected to the outflow flow path 43. In this way, the flow path switching device 5 of this embodiment operates solely through the spring 50 and the flow of liquefied gas.

[0089] Before operating the submersible pump 1, it is cooled by liquefied gas. Cooling is performed when the submersible pump 1 has stopped operating. More specifically, as follows... Figure 2 As shown, cooling is performed with the pump-side flow path 41 closed by the valve core 47 and the container-side flow path 42 connected to the outflow flow path 43.

[0090] Figure 4 This diagram illustrates one embodiment of the submersible pump 1 for cooling. The submersible pump 1 is in a stopped state (i.e., Figure 2In the indicated state, liquefied gas is supplied into the suction container 2 through the suction port 7. The discharge valve 26 and vent valve 32 are closed, while the suction valve 22 and discharge valve 23 are open. The vent valve 32 can also be opened. The liquefied gas comes into contact with the submersible pump 1 inside the suction container 2 and is discharged through the container-side flow path 42 and the outflow flow path 43 of the flow path switching device 5 and the discharge port 8. The interior of the suction container 2 is quickly filled with liquefied gas, thereby cooling the submersible pump 1.

[0091] During cooling, submersible pump 1 is in a stopped state. Figure 4 In this configuration, the pump-side flow path 41 is closed by the valve core 47. Therefore, the liquefied gas introduced into the suction container 2 does not flow within the submersible pump 1. That is, the liquefied gas bypasses the submersible pump 1 and passes through the flow path switching device 5. As a result, accidental rotation of the impeller 15 of the submersible pump 1 can be prevented, and damage to sliding parts such as the bearing 14 can be prevented.

[0092] Figure 5 This is a diagram illustrating another embodiment of the submersible pump 1 for cooling. The submersible pump 1 is in a stopped state (i.e., Figure 2 In the indicated state, liquefied gas is supplied into the suction container 2 through the discharge port 25 connected to the bottom of the suction container 2. The suction valve 22 and vent valve 32 are closed, while the discharge valve 26 and exhaust valve 23 are open. The vent valve 32 can also be opened. Liquefied gas is introduced from the bottom of the suction container 2, and simultaneously, the liquid level of the liquefied gas in the suction container 2 gradually rises. The liquefied gas (and the gas obtained from the vaporization of the liquefied gas) comes into contact with the submersible pump 1 inside the suction container 2 and is discharged through the container-side flow path 42 and the outflow flow path 43 of the flow path switching device 5 and the discharge port 8. The interior of the suction container 2 is quickly filled with liquefied gas, thereby cooling the submersible pump 1.

[0093] During cooling, submersible pump 1 is in a stopped state. Figure 5 In this configuration, the pump-side flow path 41 is closed by the valve core 47. Therefore, the liquefied gas introduced into the suction container 2 does not flow within the submersible pump 1. That is, the liquefied gas bypasses the submersible pump 1 and passes through the flow path switching device 5. As a result, accidental rotation of the impeller 15 of the submersible pump 1 can be prevented, and damage to sliding parts such as the bearing 14 can be prevented.

[0094] In order to pressurize liquefied gas to the pressure required on the demand side, multiple pump units 100 are sometimes connected together. Figure 6 This is a schematic diagram illustrating one embodiment of a pump system comprising multiple pump units 100A, 100B, and 100C connected in series. Figure 6 In the middle, multiple pump units 100A, 100B, and 100C have the same characteristics as the reference. Figures 1 to 5The pump assembly 100 described herein has the same configuration. In the following description, the submersible pump, suction container, and flow path switching device of pump assembly 100A will be referred to as submersible pump 1A, suction container 2A, and flow path switching device 5A, respectively; the submersible pump, suction container, and flow path switching device of pump assembly 100B will be referred to as submersible pump 1B, suction container 2B, and flow path switching device 5B, respectively; and the submersible pump, suction container, and flow path switching device of pump assembly 100C will be referred to as submersible pump 1C, suction container 2C, and flow path switching device 5C, respectively.

[0095] Pump unit 100A is positioned upstream of pump unit 100B, and pump unit 100B is positioned upstream of pump unit 100C. The suction port 7A of pump unit 100A is connected to a liquefied gas storage tank 105 containing liquefied gas via suction line 34. Pump unit 100A is connected in series with pump unit 100B via connecting line 107, and pump unit 100B is connected in series with pump unit 100C via connecting line 108. More specifically, the discharge port 8A of pump unit 100A is connected to the suction port 7B of pump unit 100B via connecting line 107, and the discharge port 8B of pump unit 100B is connected to the suction port 7C of pump unit 100C via connecting line 108.

[0096] A connecting valve 114 is installed on connecting line 107, and a connecting valve 115 is installed on connecting line 108. When connecting valve 114 is closed, the connection between the discharge port 8A of pump unit 100A and the suction port 7B of pump unit 100B is blocked. When connecting valve 115 is closed, the connection between the discharge port 8B of pump unit 100B and the suction port 7C of pump unit 100C is blocked. During the operation of submersible pumps 1A, 1B, and 1C, connecting valves 114 and 115 are open.

[0097] Submersible pumps 1A, 1B, and 1C are connected in series in the order of submersible pump 1A, submersible pump 1B, and submersible pump 1C. Liquefied gas is pressurized sequentially by these submersible pumps 1A, 1B, and 1C. While submersible pumps 1A, 1B, and 1C are operating, the flow path switching devices 5A, 5B, and 5C for conveying liquefied gas are in operation. Figure 3 The state shown.

[0098] The relative position of the liquefied gas storage tank 105 with respect to the pump devices 100A, 100B, and 100C is not particularly limited. For example, if the liquefied gas storage tank 105 is positioned higher than the pump devices 100A, 100B, and 100C, the liquefied gas in the storage tank 105 can reach the pump devices 100A, 100B, and 100C due to its own weight. In other examples, if the liquefied gas storage tank 105 is positioned at the same height as or lower than the pump devices 100A, 100B, and 100C, the liquefied gas in the storage tank 105 can also be transported to the pump devices 100A, 100B, and 100C by a pump (not shown).

[0099] The pump system includes: an inlet line 121 connected to the discharge port 25A of the suction container 2A; an inlet line 122 connected to the discharge port 25B of the suction container 2B; and an inlet line 123 connected to the discharge port 25C of the suction container 2C. Inlet lines 121, 122, and 123 are connected to a liquefied gas storage tank 105 and extend from the liquefied gas storage tank 105 to the suction containers 2A, 2B, and 2C. The suction containers 2A, 2B, and 2C are connected to the liquefied gas storage tank 105 via inlet lines 121, 122, and 123.

[0100] The pump system also includes an inlet valve 125 installed on inlet line 121, an inlet valve 126 installed on inlet line 122, and an inlet valve 127 installed on inlet line 123. When inlet valves 125, 126, and 127 are opened, the discharge port 25A of suction container 2A, the discharge port 25B of suction container 2B, and the discharge port 25C of suction container 2C are connected to the liquefied gas storage tank 105. During the operation of submersible pumps 1A, 1B, and 1C, such as Figure 6 As shown, inlet valves 125, 126, and 127 are closed.

[0101] Discharge valves 26A, 26B, and 26C are connected to discharge ports 25A, 25B, and 25C, respectively. During the operation of submersible pumps 1A, 1B, and 1C, if... Figure 6 As shown, discharge valves 26A, 26B, and 26C are closed.

[0102] like Figure 6As shown, during the operation of submersible pumps 1A, 1B, and 1C, the suction valve 22A connected to the suction port 7A of suction container 2A, the suction valve 22B connected to the suction port 7B of suction container 2B, and the suction valve 22C connected to the suction port 7C of suction container 2C are opened. Similarly, during the operation of submersible pumps 1A, 1B, and 1C, the discharge valve 23A connected to the discharge port 8A of suction container 2A, the discharge valve 23B connected to the discharge port 8B of suction container 2B, and the discharge valve 23C connected to the discharge port 8C of suction container 2C are opened.

[0103] The pump system also includes an outlet line 131 connected to the outlet port 8A of the suction container 2A, an outlet valve 132 installed on the outlet line 131, an outlet line 133 connected to the outlet port 8B of the suction container 2B, and an outlet valve 134 installed on the outlet line 133. The outlet valve 132 is located downstream of the outlet valve 23A, and a connecting valve 114 is located between the outlet valve 23A and the outlet valve 132. The outlet valve 134 is located downstream of the outlet valve 23B, and a connecting valve 115 is located between the outlet valve 23B and the outlet valve 134.

[0104] Figure 7 This diagram illustrates one embodiment of cooling for submersible pumps 1A, 1B, and 1C. (See diagram for example.) Figure 7 As shown, liquefied gas flows simultaneously (in parallel) into suction containers 2A, 2B, and 2C through the discharge ports 25A, 25B, and 25C of pump units 100A, 100B, and 100C, respectively. Suction valves 22A, 22B, and 22C and discharge valves 26A, 26B, and 26C are closed, while inlet valves 125, 126, and 127 are open. Discharge valves 23A, 23B, and 23C are open, as are outlet valves 132 and 134. Connecting valves 114 and 115 are closed.

[0105] During cooling, submersible pumps 1A, 1B, and 1C are in a stopped state. Therefore, flow path switching devices 5A, 5B, and 5C are in operation. Figure 2 The state is shown. Therefore, the liquefied gas bypasses submersible pumps 1A, 1B, and 1C (i.e., the liquefied gas does not flow inside submersible pumps 1A, 1B, and 1C) and passes through the flow path switching devices 5A, 5B, and 5C. The liquefied gas forms a parallel flow within the suction containers 2A, 2B, and 2C, cooling the submersible pumps 1A, 1B, and 1C. The liquefied gas flows out simultaneously (in parallel) from the suction containers 2A, 2B, and 2C through the discharge ports 8A, 8B, and 8C.

[0106] In this way, it is possible to prevent the liquefied gas introduced into the suction containers 2A, 2B, and 2C by the flow path switching devices 5A, 5B, and 5C during cooling from passing through the submersible pumps 1A, 1B, and 1C. Therefore, the impellers of the submersible pumps 1A, 1B, and 1C will not rotate when they are stopped, thus preventing damage to the sliding parts such as the bearings of the submersible pumps 1A, 1B, and 1C. In particular, because the liquefied gas forms a parallel flow within the suction containers 2A, 2B, and 2C, the submersible pumps 1A, 1B, and 1C can be cooled simultaneously and for a short time.

[0107] Figure 8 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units 100A, 100B, and 100C connected in series. Unless otherwise specified, the configuration and operation of this embodiment are referenced. Figure 6 and Figure 7 The implementation methods described are the same, so repeated descriptions are omitted.

[0108] like Figure 8 As shown, inlet lines 122 and 123 replace outlet ports 25B and 25C and are connected to the intake ports 7B and 7C of intake containers 2B and 2C, respectively. Inlet valves 126 and 127 are installed on inlet lines 122 and 123, respectively. In this embodiment, inlet line 121 and inlet valve 125 are not provided; intake line 34 and intake valve 22A are equivalent to inlet line 121 and inlet valve 125 in the above-described embodiment.

[0109] Suction line 34, inlet line 122, and inlet line 123 are connected to liquefied gas storage tank 105 and extend from liquefied gas storage tank 105 to suction containers 2A, 2B, and 2C. During the operation of submersible pumps 1A, 1B, and 1C, inlet valves 126 and 127 are closed.

[0110] Figure 9 It shows the... Figure 8 The diagram shows one embodiment of cooling using submersible pumps 1A, 1B, and 1C. During cooling, as... Figure 9 As shown, inlet valves 126 and 127 are open. Liquefied gas flows simultaneously (in parallel) into suction containers 2A, 2B, and 2C through suction ports 7A, 7B, and 7C of pump units 100A, 100B, and 100C. Suction valves 22A, 22B, and 22C are open, discharge valves 26A, 26B, and 26C are closed, and inlet valves 126 and 127 are open. Discharge valves 23A, 23B, and 23C are open, and outlet valves 132 and 134 are open. Connecting valves 114 and 115 are closed.

[0111] During cooling, submersible pumps 1A, 1B, and 1C are in a stopped state. Therefore, flow path switching devices 5A, 5B, and 5C are in operation. Figure 2 The state is shown. Therefore, the liquefied gas bypasses submersible pumps 1A, 1B, and 1C (i.e., the liquefied gas does not flow inside submersible pumps 1A, 1B, and 1C) and passes through the flow path switching devices 5A, 5B, and 5C. The liquefied gas forms a parallel flow within the suction containers 2A, 2B, and 2C, cooling the submersible pumps 1A, 1B, and 1C. The liquefied gas flows out simultaneously (in parallel) from the suction containers 2A, 2B, and 2C through the discharge ports 8A, 8B, and 8C.

[0112] In this way, the flow path switching devices 5A, 5B, and 5C prevent liquefied gas introduced into the suction containers 2A, 2B, and 2C during cooling from passing through the submersible pumps 1A, 1B, and 1C. Therefore, the impellers of the submersible pumps 1A, 1B, and 1C do not rotate when they are stopped, thus preventing damage to the sliding parts such as the bearings of the submersible pumps 1A, 1B, and 1C. In particular, because the liquefied gas forms a parallel flow within the suction containers 2A, 2B, and 2C, the submersible pumps 1A, 1B, and 1C can be cooled simultaneously and for a short time.

[0113] Figure 10 This is a schematic diagram illustrating one embodiment of cooling a pump system having multiple pump units connected in series and parallel. Unless otherwise specified, the configuration and operation of this embodiment are referenced. Figure 6 and Figure 7 The implementation methods described are the same, so repeated descriptions are omitted. Figure 10 The pump system of the illustrated embodiment also includes features similar to those in the reference embodiment. Figure 7 Pump units 100D, 100E, and 100F have the same configuration as pump units 100A, 100B, and 100C. Pump units 100A, 100B, and 100C are connected in series, and pump units 100D, 100E, and 100F are connected in series. Pump units 100D, 100E, and 100F are arranged in parallel with pump units 100A, 100B, and 100C.

[0114] Pump assembly 100D includes a suction container 2D, a submersible pump 1D disposed within the suction container 2D, and a flow path switching device 5D. Pump assembly 100E includes a suction container 2E, a submersible pump 1E disposed within the suction container 2E, and a flow path switching device 5E. Pump assembly 100F includes a suction container 2F, a submersible pump 1F disposed within the suction container 2F, and a flow path switching device 5F. The suction port 7A of the suction container 2A is connected to the liquefied gas storage tank 105 via a suction line 34, and the suction port 7D of the suction container 2D is connected to the liquefied gas storage tank 105 via a suction line 35.

[0115] Pump unit 100D is connected in series with pump unit 100E via connecting line 109, and pump unit 100E is connected in series with pump unit 100F via connecting line 110. More specifically, the discharge port 8D of pump unit 100D is connected to the suction port 7E of pump unit 100E via connecting line 109, and the discharge port 8E of pump unit 100E is connected to the suction port 7F of pump unit 100F via connecting line 110.

[0116] A connecting valve 151 is installed on connecting line 109, and a connecting valve 152 is installed on connecting line 110. When connecting valve 151 is closed, the connection between the discharge port 8D of pump unit 100D and the suction port 7E of pump unit 100E is blocked. When connecting valve 152 is closed, the connection between the discharge port 8E of pump unit 100E and the suction port 7F of pump unit 100F is blocked. During the operation of submersible pumps 1D, 1E, and 1F, connecting valves 151 and 152 are open.

[0117] The pump system includes an inlet line 141 connected to the discharge port 25D of the suction container 2D, an inlet line 142 connected to the discharge port 25E of the suction container 2E, and an inlet line 143 connected to the discharge port 25F of the suction container 2F. Inlet lines 141, 142, and 143 are connected to the liquefied gas storage tank 105 and extend from the liquefied gas storage tank 105 to the suction containers 2D, 2E, and 2F. That is, the suction containers 2D, 2E, and 2F are connected to the liquefied gas storage tank 105 via inlet lines 141, 142, and 143.

[0118] The pump system also includes an inlet valve 145 installed on inlet line 141, an inlet valve 146 installed on inlet line 142, and an inlet valve 147 installed on inlet line 143. When inlet valves 145, 146, and 147 are open, the discharge ports 25D, 25E, and 25F of suction container 2D, suction container 2E, and suction container 2F are connected to the liquefied gas storage tank 105. During the operation of submersible pumps 1D, 1E, and 1F, inlet valves 145, 146, and 147 are closed.

[0119] The pump system also includes an outlet line 161 connected to the outlet port 8D of the suction container 2D, an outlet valve 162 installed on the outlet line 161, an outlet line 163 connected to the outlet port 8E of the suction container 2E, and an outlet valve 164 installed on the outlet line 163. The outlet valve 162 is located downstream of the discharge valve 23D, and a connecting valve 151 is located between the discharge valve 23D and the outlet valve 162. The outlet valve 164 is located downstream of the discharge valve 23E, and a connecting valve 152 is located between the discharge valve 23E and the outlet valve 164.

[0120] Multiple pump units 100A, 100B, 100C, 100D, 100E, and 100F have the same characteristics as the reference. Figures 1 to 3 The pump assembly 100 described has the same configuration, so its repeated description is omitted. In pump assemblies 100A, 100B, 100C, 100D, 100E, and 100F, the corresponding components are given the same reference numerals and are indicated by the suffixes A, B, C, D, E, and F.

[0121] Liquefied gas flows into the intake containers 2A, 2B, 2C, 2D, 2E, and 2F simultaneously (in parallel) through the discharge ports 25A, 25B, 25C, 25D, 25E, and 25F of the intake containers 2A, 2B, 2C, 2D, 2E, and 2F.

[0122] like Figure 10 As shown, during cooling, submersible pumps 1A, 1B, 1C, 1D, 1E, and 1F are in a stopped state. Therefore, flow path switching devices 5A, 5B, 5C, 5D, 5E, and 5F are in operation. Figure 2 The state is shown. Therefore, the liquefied gas bypasses submersible pumps 1A, 1B, 1C, 1D, 1E, 1F (i.e., the liquefied gas does not flow inside submersible pumps 1A, 1B, 1C, 1D, 1E, 1F) and passes through the flow path switching devices 5A, 5B, 5C, 5D, 5E, 5F. The liquefied gas forms a parallel flow within the suction containers 2A, 2B, 2C, 2D, 2E, 2F, cooling the submersible pumps 1A, 1B, 1C, 1D, 1E, 1F. The liquefied gas simultaneously flows out from the suction containers 2A, 2B, 2C, 2D, 2E, 2F through the discharge ports 8A, 8B, 8C, 8D, 8E, 8F.

[0123] In this manner, the flow path switching devices 5A, 5B, 5C, 5D, 5E, and 5F prevent liquefied gas introduced into the suction containers 2A, 2B, 2C, 2D, 2E, and 2F during cooling from passing through the submersible pumps 1A, 1B, 1C, 1D, 1E, and 1F. Therefore, the impellers of the submersible pumps 1A, 1B, 1C, 1D, 1E, and 1F will not rotate when the pumps are stopped, thus preventing damage to the sliding parts such as the bearings of the submersible pumps 1A, 1B, 1C, 1D, 1E, and 1F. In particular, the liquefied gas forms a parallel flow within the suction containers 2A, 2B, 2C, 2D, 2E, and 2F, thus enabling simultaneous and short-term cooling of the submersible pumps 1A, 1B, 1C, 1D, 1E, and 1F.

[0124] Figure 11 This is a schematic diagram illustrating another embodiment for cooling a pump system having multiple pump units connected in series and parallel. Unless otherwise specified, the configuration and operation of this embodiment are referenced. Figures 8 to 10The implementation methods described are the same, so repeated descriptions are omitted. Figure 11 The pump system of the illustrated embodiment also includes features similar to those in the reference embodiment. Figure 8 Pump units 100D, 100E, and 100F have the same configuration as pump units 100A, 100B, and 100C. Pump units 100A, 100B, and 100C are connected in series, and pump units 100D, 100E, and 100F are connected in series. Pump units 100D, 100E, and 100F are arranged in parallel with pump units 100A, 100B, and 100C.

[0125] Inlet lines 142 and 143 are connected to the suction ports 7E and 7F of suction containers 2E and 2F, respectively. Inlet valves 146 and 147 are installed on inlet lines 142 and 143, respectively. Suction line 35 and suction valve 22D constitute an inlet line and valve for introducing liquefied gas into suction container 2D for cooling. Suction lines 35, 142, and 143 are connected to liquefied gas storage tank 105 and extend from liquefied gas storage tank 105 to suction containers 2D, 2E, and 2F. During the operation of submersible pumps 1D, 1E, and 1F, inlet valves 146 and 147 are closed. During cooling, if... Figure 11 As shown, inlet valve 146 and inlet valve 147 are open.

[0126] During cooling, liquefied gas flows in simultaneously (in parallel) through the suction ports 7A, 7B, 7C, 7D, 7E, and 7F of the suction containers 2A, 2B, 2C, 2D, 2E, and 2F of pump units 100A, 100B, 100C, 100D, 100E, and 100F. For example... Figure 11 As shown, during cooling, submersible pumps 1A, 1B, 1C, 1D, 1E, and 1F are in a stopped state. Therefore, flow path switching devices 5A, 5B, 5C, 5D, 5E, and 5F are in operation. Figure 2 The state is shown. Therefore, the liquefied gas bypasses submersible pumps 1A, 1B, 1C, 1D, 1E, 1F (i.e., the liquefied gas does not flow inside submersible pumps 1A, 1B, 1C, 1D, 1E, 1F) and passes through the flow path switching devices 5A, 5B, 5C, 5D, 5E, 5F. The liquefied gas forms a parallel flow within the suction containers 2A, 2B, 2C, 2D, 2E, 2F, cooling the submersible pumps 1A, 1B, 1C, 1D, 1E, 1F. The liquefied gas simultaneously flows out from the suction containers 2A, 2B, 2C, 2D, 2E, 2F through the discharge ports 8A, 8B, 8C, 8D, 8E, 8F.

[0127] In this manner, the flow path switching devices 5A, 5B, 5C, 5D, 5E, and 5F prevent liquefied gas introduced into the suction containers 2A, 2B, 2C, 2D, 2E, and 2F during cooling from passing through the submersible pumps 1A, 1B, 1C, 1D, 1E, and 1F. Therefore, the impellers of the submersible pumps 1A, 1B, 1C, 1D, 1E, and 1F will not rotate when the pumps are stopped, thus preventing damage to the sliding parts such as the bearings of the submersible pumps 1A, 1B, 1C, 1D, 1E, and 1F. In particular, because the liquefied gas forms a parallel flow within the suction containers 2A, 2B, 2C, 2D, 2E, and 2F, the submersible pumps 1A, 1B, 1C, 1D, 1E, and 1F can be cooled simultaneously and for a short period of time.

[0128] Figure 12 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units 100A, 100B, and 100C connected in series. Unless otherwise specified, the configuration and operation of this embodiment are referenced. Figure 6 The implementation methods described are the same, so repeated descriptions are omitted. Figure 12 The pump system shown does not have Figure 6 The connecting valves 114 and 115, inlet line 121, inlet line 122, inlet line 123, inlet valve 125, inlet valve 126, inlet valve 127, outlet line 131, outlet line 133, outlet valve 132, and outlet valve 134 shown are consistent with this. Figure 6 The implementation methods shown are different, but the other components are the same.

[0129] Figure 13 and Figure 14 It shows that it is aimed at Figure 12 The diagram illustrates one implementation of a pump system for cooling. (As shown) Figure 13 As shown, suction valves 22A, 22B, and 22C are open, discharge valves 26A, 26B, and 26C are closed, and discharge valves 23A, 23B, and 23C are open. First, with all submersible pumps 1A, 1B, and 1C completely stopped, liquefied gas flows into suction container 2A through suction port 7A of pump unit 100A. The liquefied gas comes into contact with the room-temperature suction container 2A and submersible pump 1A and evaporates, forming evaporated gas. Figure 13 In the diagram, the flow of evaporating gas is represented by a dashed line.

[0130] More specifically, liquefied gas is first introduced into the suction container 2A of pump assembly 100A through suction port 7A. The liquefied gas evaporates in suction container 2A, forming evaporated gas. The evaporated gas passes through flow path switching device 5A while bypassing submersible pump 1A. The evaporated gas passing through flow path switching device 5A is then introduced into suction container 2B through connecting line 107 and suction port 7B of pump assembly 100B. The evaporated gas passes through flow path switching device 5B while bypassing submersible pump 1B. Furthermore, the evaporated gas passing through flow path switching device 5B is introduced into suction container 2C through connecting line 108 and suction port 7C of pump assembly 100C. The evaporated gas passes through flow path switching device 5C while bypassing submersible pump 1C. The evaporated gas is discharged through discharge port 8C of pump assembly 100C.

[0131] Next, as Figure 14 As shown, submersible pump 1A starts. Submersible pumps 1B and 1C remain stationary. Through the operation of submersible pump 1A, liquefied gas flows into suction container 2A through suction port 7A. Submersible pump 1A sequentially delivers liquefied gas into suction containers 2B and 2C. More specifically, the liquefied gas is pressurized by the operation of submersible pump 1A and passes through flow path switching device 5A. The liquefied gas passing through flow path switching device 5A is introduced into suction container 2B through connecting line 107 and suction port 7B of pump device 100B. The liquefied gas passes through flow path switching device 5B while bypassing submersible pump 1B. Furthermore, the liquefied gas passing through flow path switching device 5B is introduced into suction container 2C through connecting line 108 and suction port 7C of pump device 100C. The liquefied gas passes through flow path switching device 5C while bypassing submersible pump 1C. The liquefied gas is discharged through the discharge port 8C of the pump unit 100C.

[0132] In this way, the flow path switching devices 5A, 5B, and 5C can prevent liquefied gas and evaporated gas from passing through the submersible pumps 1A, 1B, and 1C when they are stopped from operation during cooling. Therefore, the impellers of the submersible pumps 1A, 1B, and 1C will not rotate when they are stopped, which prevents damage to the sliding parts such as the bearings of the submersible pumps 1A, 1B, and 1C.

[0133] Figure 15 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units 100A, 100B, and 100C connected in series. Unless otherwise specified, the configuration and operation of this embodiment are referenced. Figure 6 The implementation methods described are the same, so repeated descriptions are omitted.

[0134] like Figure 15As shown, the pump system of this embodiment includes an inlet line 171 connected to the discharge port 25A of the liquefied gas storage tank 105 and the suction container 2A, an inlet line 172 connected to the discharge port 8A of the suction container 2A and the discharge port 25B of the suction container 2B, and an inlet line 173 connected to the discharge port 8B of the suction container 2B and the discharge port 25C of the suction container 2C. The pump system also includes an inlet valve 176 installed on the inlet line 171, an inlet valve 177 installed on the inlet line 172, and an inlet valve 178 installed on the inlet line 173.

[0135] Inlet line 171 extends from liquefied gas storage tank 105 to outlet port 25A of suction container 2A. When inlet valve 176 is opened, outlet port 25A of suction container 2A is connected to liquefied gas storage tank 105 via inlet line 171. Inlet line 172 extends from outlet port 8A of suction container 2A to outlet port 25B of suction container 2B. When inlet valve 177 is opened, outlet port 25B of suction container 2B is connected to outlet port 8A of suction container 2A via inlet line 172. Inlet line 173 extends from outlet port 8B of suction container 2B to outlet port 25C of suction container 2C. When inlet valve 178 is opened, outlet port 25C of suction container 2C is connected to outlet port 8B of suction container 2B via inlet line 173. Figure 15 As shown, during the operation of submersible pumps 1A, 1B, and 1C, inlet valves 176, 177, and 178 are closed.

[0136] Figure 16 and Figure 17 It shows that it is aimed at Figure 15 The diagram illustrates one implementation of a pump system for cooling. (As shown) Figure 16 As shown, suction valves 22A, 22B, and 22C are closed, discharge valves 26A, 26B, and 26C are closed, discharge valves 23A, 23B, and 23C are open, and inlet valves 176, 177, and 178 are open.

[0137] First, with all submersible pumps 1A, 1B, and 1C stopped, liquefied gas flows into suction container 2A through inlet line 171 and discharge port 25A. The liquefied gas evaporates upon contact with the ambient temperature suction container 2A and submersible pump 1A, forming evaporated gas. Figure 16 In the diagram, the flow of evaporating gas is represented by a dashed line.

[0138] More specifically, firstly, liquefied gas is introduced into the suction container 2A of pump unit 100A through discharge port 25A. The liquefied gas evaporates within suction container 2A, forming evaporated gas. The evaporated gas passes through flow path switching device 5A while bypassing submersible pump 1A. The evaporated gas passing through flow path switching device 5A is then introduced into suction container 2B through inlet line 172 and discharge port 25B of pump unit 100B. The evaporated gas passes through flow path switching device 5B while bypassing submersible pump 1B. Furthermore, the evaporated gas passing through flow path switching device 5B is introduced into suction container 2C through inlet line 173 and discharge port 25C of pump unit 100C. The evaporated gas passes through flow path switching device 5C while bypassing submersible pump 1C. The evaporated gas is discharged through discharge port 8C of pump unit 100C.

[0139] Next, as Figure 17 As shown, suction valve 22A is open and inlet valve 176 is closed. Submersible pump 1A is started. Submersible pumps 1B and 1C remain stationary. Through the operation of submersible pump 1A, liquefied gas flows into suction container 2A through suction port 7A.

[0140] Submersible pump 1A sequentially feeds liquefied gas into suction containers 2B and 2C. More specifically, the liquefied gas is pressurized by the operation of submersible pump 1A and passes through flow path switching device 5A. The liquefied gas passing through flow path switching device 5A is introduced into suction container 2B through inlet line 172 and discharge port 25B of pump device 100B. The liquefied gas passes through flow path switching device 5B while bypassing submersible pump 1B. Furthermore, the liquefied gas passing through flow path switching device 5B is introduced into suction container 2C through inlet line 173 and discharge port 25C of pump device 100C. The liquefied gas passes through flow path switching device 5C while bypassing submersible pump 1C. The liquefied gas is discharged through discharge port 8C of pump device 100C.

[0141] In this way, the flow path switching devices 5A, 5B, and 5C can prevent liquefied gas and evaporated gas from passing through the submersible pumps 1A, 1B, and 1C when they are stopped from operation during cooling. Therefore, the impellers of the submersible pumps 1A, 1B, and 1C will not rotate when they are stopped, which prevents damage to the sliding parts such as the bearings of the submersible pumps 1A, 1B, and 1C.

[0142] Figure 18 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units 100A, 100B, and 100C connected in series. Unless otherwise specified, the configuration and operation of this embodiment are referenced. Figure 15 The implementation methods described are the same, so repeated descriptions are omitted. Figure 18The pump system of this embodiment shown includes an inlet line 181 connected to the discharge port 8A of the suction container 2A and the discharge port 25C of the suction container 2C, and an inlet valve 182 installed on the inlet line 181. The discharge port 8A of the suction container 2A is connected to both the discharge ports 25B and 25C of the suction container 2B via the inlet line 172 and the inlet line 181.

[0143] When inlet valve 176 is opened, the discharge port 25A of suction container 2A is connected to liquefied gas storage tank 105 via inlet line 171. When inlet valve 177 is opened, the discharge port 25B of suction container 2B is connected to the discharge port 8A of suction container 2A via inlet line 172. Inlet line 181 bypasses pump assembly 100B and extends from discharge port 8A of suction container 2A to discharge port 25C of suction container 2C. When inlet valve 182 is opened, the discharge port 25C of suction container 2C is connected to discharge port 8A of suction container 2A via inlet line 181.

[0144] The pump system of this embodiment also includes an outlet line 133 connected to the outlet port 8B of the suction container 2B and an outlet valve 134 installed on the outlet line 133. The outlet valve 134 is located downstream of the outlet valve 23B. Figure 18 As shown, during the operation of submersible pumps 1A, 1B, and 1C, inlet valves 176, 177, and 182 are closed, and outlet valve 134 is also closed.

[0145] Figure 19 and Figure 20 It shows that it is aimed at Figure 18 The diagram illustrates one implementation of a pump system for cooling. (As shown) Figure 19 As shown, suction valves 22A, 22B, and 22C are closed, discharge valves 26A, 26B, and 26C are closed, and discharge valves 23A, 23B, and 23C are open. Inlet valves 176, 177, and 182 are open, and outlet valve 134 is open.

[0146] First, with all submersible pumps 1A, 1B, and 1C stopped, liquefied gas flows into suction container 2A through inlet line 171 and discharge port 25A. The liquefied gas evaporates upon contact with the ambient temperature suction container 2A and submersible pump 1A, forming evaporated gas. Figure 19 In the diagram, the flow of evaporating gas is represented by a dashed line.

[0147] More specifically, firstly, liquefied gas is introduced into the suction container 2A of pump assembly 100A through discharge port 25A. The liquefied gas evaporates within suction container 2A, forming evaporated gas. The evaporated gas passes through flow path switching device 5A while bypassing submersible pump 1A. The evaporated gas passing through flow path switching device 5A is introduced into suction container 2B through inlet line 172 and discharge port 25B of pump assembly 100B, and simultaneously into suction container 2C through inlet line 181 and discharge port 25C of pump assembly 100C. Inlet lines 172 and 181 are pre-cooled by the evaporated gas. The evaporated gas passes through flow path switching device 5B while bypassing submersible pump 1B. The evaporated gas passing through flow path switching device 5B is discharged from suction container 2B through discharge port 8B and outflow line 133. Similarly, the evaporated gas passes through flow path switching device 5C while bypassing submersible pump 1C. The evaporated gas passing through the flow path switching device 5C is discharged from the suction container 2C through the discharge port 8C.

[0148] Next, as Figure 20 As shown, suction valve 22A is open and inlet valve 176 is closed. Submersible pump 1A starts. Submersible pumps 1B and 1C remain stationary. Due to the operation of submersible pump 1A, liquefied gas flows into suction container 2A through suction port 7A.

[0149] Submersible pump 1A simultaneously (i.e., in parallel) delivers liquefied gas into suction containers 2B and 2C. More specifically, the liquefied gas is pressurized by the operation of submersible pump 1A and passes through flow path switching device 5A. The liquefied gas passing through flow path switching device 5A is introduced into suction container 2B through inlet line 172 and discharge port 25B of pump device 100B, and simultaneously introduced into suction container 2C through inlet line 181 and discharge port 25C of pump device 100C. The liquefied gas passes through flow path switching device 5B while bypassing submersible pump 1B. The liquefied gas passing through flow path switching device 5B is discharged from suction container 2B through discharge port 8B and outflow line 133. Similarly, the liquefied gas passes through flow path switching device 5C while bypassing submersible pump 1C. The liquefied gas passing through flow path switching device 5C is discharged from suction container 2C through discharge port 8C.

[0150] In this way, the flow path switching devices 5A, 5B, and 5C can prevent liquefied gas and evaporated gas from passing through the submersible pumps 1A, 1B, and 1C when they are stopped from operation during cooling. Therefore, the impellers of the submersible pumps 1A, 1B, and 1C will not rotate when they are stopped, which prevents damage to the sliding parts such as the bearings of the submersible pumps 1A, 1B, and 1C.

[0151] Figure 21This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units 100A, 100B, and 100C connected in series. Unless otherwise specified, the configuration and operation of this embodiment are referenced. Figure 12 The implementation methods described are the same, so repeated descriptions are omitted. Figure 21 The pump system shown also includes an inlet line 191 connected to the discharge port 8A of the suction container 2A of the pump device 100A and the suction port 7C of the suction container 2C of the pump device 100C, an inlet valve 192 installed on the inlet line 191, an outlet line 133 connected to the discharge port 8B of the suction container 2B of the pump device 100B, an outlet valve 134 installed on the outlet line 133, and a connecting valve 115 installed on the connecting line 108.

[0152] The inlet line 191 bypasses the pump assembly 100B and extends from the discharge port 8A of the suction container 2A to the suction port 7C of the suction container 2C. When the inlet valve 192 is opened, the discharge port 8A of the suction container 2A and the suction port 7C of the suction container 2C are connected via the inlet line 191. A connecting valve 115 is located between the discharge valve 23B and the outflow valve 134. Figure 21 As shown, during the operation of submersible pumps 1A, 1B, and 1C, the inlet valve 192 and outlet valve 134 are closed, while the connecting valve 115 is open.

[0153] Figure 22 and Figure 23 It shows that it is aimed at Figure 21 The diagram illustrates one implementation of a pump system for cooling. (As shown) Figure 22 As shown, suction valves 22A, 22B, and 22C are open, discharge valves 26A, 26B, and 26C are closed, and discharge valves 23A, 23B, and 23C are open. Connecting valve 115 is closed, and inlet valve 192 and outlet valve 134 are open.

[0154] First, with all submersible pumps 1A, 1B, and 1C stopped, liquefied gas flows into suction container 2A through the suction port 7A of pump unit 100A. The liquefied gas comes into contact with the room-temperature suction container 2A and submersible pump 1A and evaporates, forming evaporated gas. Figure 22 In the diagram, the flow of evaporating gas is represented by a dashed line.

[0155] More specifically, firstly, liquefied gas is introduced into the suction container 2A of pump assembly 100A through suction port 7A. The liquefied gas evaporates within suction container 2A, forming evaporated gas. The evaporated gas passes through flow path switching device 5A while bypassing submersible pump 1A. The evaporated gas passing through flow path switching device 5A is introduced into suction container 2B through connecting line 107 and suction port 7B of pump assembly 100B, and simultaneously into suction container 2C through inlet line 191 and suction port 7C of pump assembly 100C. Connecting line 107 and inlet line 191 are pre-cooled by the evaporated gas. The evaporated gas passes through flow path switching device 5B while bypassing submersible pump 1B. The evaporated gas passing through flow path switching device 5B is discharged from suction container 2B through discharge port 8B and outlet line 133. Similarly, the evaporated gas passes through flow path switching device 5C while bypassing submersible pump 1C. The evaporated gas passing through the flow path switching device 5C is discharged from the suction container 2C through the discharge port 8C.

[0156] Next, as Figure 23 As shown, submersible pump 1A starts. Submersible pumps 1B and 1C remain stationary. Due to the operation of submersible pump 1A, liquefied gas flows into suction container 2A through suction port 7A.

[0157] Submersible pump 1A simultaneously (i.e., in parallel) delivers liquefied gas into suction containers 2B and 2C. More specifically, the liquefied gas is pressurized by the operation of submersible pump 1A and passes through flow path switching device 5A. The liquefied gas passing through flow path switching device 5A is introduced into suction container 2B via connecting line 107 and suction port 7B of pump device 100B, and simultaneously, into suction container 2C via inlet line 191 and suction port 7C of pump device 100C. The liquefied gas passes through flow path switching device 5B while bypassing submersible pump 1B. The liquefied gas passing through flow path switching device 5B is discharged from suction container 2B through discharge port 8B and outflow line 133. Similarly, the liquefied gas passes through flow path switching device 5C while bypassing submersible pump 1C. The liquefied gas passing through flow path switching device 5C is discharged from suction container 2C through discharge port 8C.

[0158] In this way, the flow path switching devices 5A, 5B, and 5C can prevent liquefied gas and evaporated gas from passing through the submersible pumps 1A, 1B, and 1C when they are stopped from operation during cooling. Therefore, the impellers of the submersible pumps 1A, 1B, and 1C will not rotate when they are stopped, which prevents damage to the sliding parts such as the bearings of the submersible pumps 1A, 1B, and 1C.

[0159] Reference Figures 12 to 23 The described implementation method can also be applied to pump systems in which multiple pump units are arranged in series and parallel. For example, Figure 24The pump system of the illustrated embodiment includes reference Figure 12 Pump units 100A, 100B, and 100C are described, as well as pump units 100D, 100E, and 100F having the same configuration. Pump units 100A, 100B, and 100C are connected in series, and pump units 100D, 100E, and 100F are also connected in series. Pump units 100D, 100E, and 100F are arranged in parallel with pump units 100A, 100B, and 100C.

[0160] The suction port 7A of suction container 2A is connected to liquefied gas storage tank 105 via suction line 34, and the suction port 7D of suction container 2D is connected to liquefied gas storage tank 105 via suction line 35. The discharge port 8D of pump device 100D is connected to suction port 7E of pump device 100E via connecting line 109, and the discharge port 8E of pump device 100E is connected to suction port 7F of pump device 100F via connecting line 110.

[0161] Temperature reduction and reference for submersible pumps 1A, 1B, 1C, 1D, 1E, and 1F Figure 13 and Figure 14 The implementation method described herein is carried out in the same manner. That is, as follows: Figure 25 As shown, with all submersible pumps 1A, 1B, 1C, 1D, 1E, and 1F completely stopped, liquefied gas flows into suction containers 2A and 2D. The liquefied gas evaporates upon contact with the room-temperature suction containers 2A and 2D and the submersible pumps 1A and 1D, forming evaporated gas. Figure 25 In the diagram, the flow of the evaporating gas is represented by dashed lines. The evaporating gas flows from suction container 2A to suction containers 2B and 2C, while simultaneously flowing from suction container 2D to suction containers 2E and 2F. Submersible pumps 1A and 1D within suction containers 2A and 2D are cooled by liquefied gas, while submersible pumps 1B, 1C, 1E, and 1F within suction containers 2B, 2C, 2E, and 2F are pre-cooled by the evaporating gas.

[0162] Next, as Figure 26 As shown, submersible pumps 1A and 1D are started. Submersible pumps 1B, 1C, 1E, and 1F remain stationary. Through the operation of submersible pump 1A, liquefied gas flows into suction container 2A through suction port 7A. Submersible pump 1A sequentially delivers liquefied gas into suction containers 2B and 2C. Through the operation of submersible pump 1D, liquefied gas flows into suction container 2D through suction port 7D. Submersible pump 1D sequentially delivers liquefied gas into suction containers 2E and 2F. Submersible pumps 1A, 1B, 1C, 1D, 1E, and 1F are cooled by the liquefied gas.

[0163] Although not illustrated, it is for reference. Figures 15 to 23Pump systems with multiple pump units of the same configuration arranged in series and parallel as described in the embodiments can perform cooling in the same way.

[0164] Figure 27 This is a schematic diagram illustrating one embodiment of a pump system having multiple pump units 100A, 100B, and 100C connected in parallel. The configuration and reference of pump units 100A, 100B, and 100C are shown. Figures 1 to 5 The implementation methods described are the same, so repeated descriptions are omitted.

[0165] In this embodiment, the suction port 7A of suction container 2A is connected to liquefied gas storage tank 105 via suction line 34, the suction port 7B of suction container 2B is connected to liquefied gas storage tank 105 via suction line 35, and the suction port 7C of suction container 2C is connected to liquefied gas storage tank 105 via suction line 36. Suction line 36 extends from liquefied gas storage tank 105 to suction port 7C of suction container 2C. Discharge line 201 is connected to discharge port 8A of suction container 2A, and outlet valve 202 is installed on discharge line 201. Discharge line 203 is connected to discharge port 8B of suction container 2B, and outlet valve 204 is installed on discharge line 203.

[0166] The pump system of this embodiment includes: an inlet line 211 connected to the discharge port 25A of the liquefied gas storage tank 105 and the suction container 2A; an inlet line 212 connected to the discharge port 8A of the suction container 2A and the discharge port 25B of the suction container 2B; and an inlet line 213 connected to the discharge port 8B of the suction container 2B and the discharge port 25C of the suction container 2C. The pump system also includes: an inlet valve 215 installed on the inlet line 211; an inlet valve 216 installed on the inlet line 212; and an inlet valve 217 installed on the inlet line 213.

[0167] Inlet line 211 extends from liquefied gas storage tank 105 to outlet port 25A of suction container 2A. When inlet valve 215 is opened, outlet port 25A of suction container 2A is connected to liquefied gas storage tank 105 via inlet line 211. Inlet line 212 extends from outlet port 8A of suction container 2A to outlet port 25B of suction container 2B. When inlet valve 216 is opened, outlet port 25B of suction container 2B is connected to outlet port 8A of suction container 2A via inlet line 212. Inlet line 213 extends from outlet port 8B of suction container 2B to outlet port 25C of suction container 2C. When inlet valve 217 is opened, outlet port 25C of suction container 2C is connected to outlet port 8B of suction container 2B via inlet line 213. Figure 27As shown, during the operation of submersible pumps 1A, 1B, and 1C, inlet valves 215, 216, and 217 are closed, while outlet valves 202 and 204 are open.

[0168] Figure 28 and Figure 29 It shows that it is aimed at Figure 27 The diagram illustrates one implementation of a pump system for cooling. (As shown) Figure 28 As shown, suction valves 22A, 22B, and 22C are closed, discharge valves 26A, 26B, and 26C are closed, and discharge valves 23A, 23B, and 23C are open. Inlet valves 215, 216, and 217 are open, and outlet valves 202 and 204 are closed.

[0169] First, with all submersible pumps 1A, 1B, and 1C stopped, liquefied gas flows into suction container 2A through inlet line 211 and discharge port 25A. The liquefied gas evaporates upon contact with the ambient temperature suction container 2A and submersible pump 1A, forming evaporated gas. Figure 28 In the diagram, the flow of evaporating gas is represented by a dashed line.

[0170] More specifically, firstly, liquefied gas is introduced into the suction container 2A of pump unit 100A through discharge port 25A. The liquefied gas evaporates within suction container 2A, forming evaporated gas. The evaporated gas passes through flow path switching device 5A while bypassing submersible pump 1A. The evaporated gas passing through flow path switching device 5A is then introduced into suction container 2B through inlet line 212 and discharge port 25B of pump unit 100B. The evaporated gas passes through flow path switching device 5B while bypassing submersible pump 1B. Furthermore, the evaporated gas passing through flow path switching device 5B is introduced into suction container 2C through inlet line 213 and discharge port 25C of pump unit 100C. The evaporated gas passes through flow path switching device 5C while bypassing submersible pump 1C. The evaporated gas is discharged through discharge port 8C of pump unit 100C.

[0171] Next, as Figure 29 As shown, suction valve 22A is open and inlet valve 215 is closed. Submersible pump 1A starts. Submersible pumps 1B and 1C remain stationary. Due to the operation of submersible pump 1A, liquefied gas flows into suction container 2A through suction port 7A.

[0172] Submersible pump 1A sequentially feeds liquefied gas into suction containers 2B and 2C. More specifically, the liquefied gas is pressurized by the operation of submersible pump 1A and passes through flow path switching device 5A. The liquefied gas passing through flow path switching device 5A is introduced into suction container 2B through inlet line 212 and discharge port 25B of pump device 100B. The liquefied gas passes through flow path switching device 5B while bypassing submersible pump 1B. Furthermore, the liquefied gas passing through flow path switching device 5B is introduced into suction container 2C through inlet line 213 and discharge port 25C of pump device 100C. The liquefied gas passes through flow path switching device 5C while bypassing submersible pump 1C. The liquefied gas is discharged through discharge port 8C of pump device 100C.

[0173] In this way, the flow path switching devices 5A, 5B, and 5C can prevent liquefied gas and evaporated gas from passing through the submersible pumps 1A, 1B, and 1C when they are stopped from operation during cooling. Therefore, the impellers of the submersible pumps 1A, 1B, and 1C will not rotate when they are stopped, which prevents damage to the sliding parts such as the bearings of the submersible pumps 1A, 1B, and 1C.

[0174] Figure 30 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units 100A, 100B, and 100C connected in parallel. Unless otherwise specified, the configuration and operation of this embodiment are referenced. Figures 27 to 29 The implementation methods described are the same, so repeated descriptions are omitted.

[0175] The pump system of this embodiment includes: an inlet line 221 connected to the discharge port 8A of the suction container 2A and the suction port 7B of the suction container 2B; an inlet line 222 connected to the discharge port 8B of the suction container 2B and the suction port 7C of the suction container 2C; an inlet valve 224 installed on the inlet line 221; and an inlet valve 225 installed on the inlet line 222. The pump system also includes an inlet valve 227 installed on the suction line 35 and an inlet valve 228 installed on the suction line 36. The inlet valve 227 is disposed upstream of the suction valve 22B, and the inlet valve 224 is located between the inlet valve 227 and the suction valve 22B. The inlet valve 228 is disposed upstream of the suction valve 22C, and the inlet valve 225 is located between the inlet valve 228 and the suction valve 22C.

[0176] Inlet line 221 extends from the discharge port 8A of suction container 2A to the suction port 7B of suction container 2B. When inlet valve 224 is opened, the discharge port 8A of suction container 2A is connected to the suction port 7B of suction container 2B via inlet line 221. Inlet line 222 extends from the discharge port 8B of suction container 2B to the suction port 7C of suction container 2C. When inlet valve 225 is opened, the discharge port 8B of suction container 2B is connected to the suction port 7C of suction container 2C via inlet line 222. Figure 30 As shown, during the operation of submersible pumps 1A, 1B, and 1C, inlet valves 224 and 225 are closed, outlet valves 202 and 204 are open, and inlet valves 227 and 228 are open.

[0177] Figure 31 and Figure 32 It shows that it is aimed at Figure 30 The diagram illustrates one implementation of a pump system for cooling. (As shown) Figure 30 As shown, suction valves 22A, 22B, and 22C are open; discharge valves 26A, 26B, and 26C are closed; and discharge valves 23A, 23B, and 23C are open. Inlet valves 224 and 225 are open; and outlet valves 202 and 204 are closed. Inlet valves 227 and 228 are closed.

[0178] First, with all submersible pumps 1A, 1B, and 1C stopped, liquefied gas flows into suction container 2A through the suction port 7A of pump unit 100A. The liquefied gas comes into contact with the room-temperature suction container 2A and submersible pump 1A and evaporates, forming evaporated gas. Figure 31 In the diagram, the flow of evaporating gas is represented by a dashed line.

[0179] More specifically, firstly, liquefied gas is introduced into the suction container 2A of pump assembly 100A through suction port 7A. The liquefied gas evaporates within suction container 2A, forming evaporated gas. The evaporated gas passes through flow path switching device 5A while bypassing submersible pump 1A. The evaporated gas passing through flow path switching device 5A is then introduced into suction container 2B via inlet line 221 and suction port 7B of pump assembly 100B. The evaporated gas passes through flow path switching device 5B while bypassing submersible pump 1B. Furthermore, the evaporated gas passing through flow path switching device 5B is introduced into suction container 2C via inlet line 222 and suction port 7C of pump assembly 100C. The evaporated gas passes through flow path switching device 5C while bypassing submersible pump 1C. The evaporated gas is discharged through discharge port 8C of pump assembly 100C.

[0180] Next, as Figure 32As shown, submersible pump 1A starts. Submersible pumps 1B and 1C remain stationary. Due to the operation of submersible pump 1A, liquefied gas flows into suction container 2A through suction port 7A. Submersible pump 1A sequentially delivers liquefied gas into suction containers 2B and 2C. More specifically, the liquefied gas is pressurized by the operation of submersible pump 1A and passes through flow path switching device 5A. The liquefied gas passing through flow path switching device 5A is introduced into suction container 2B through inlet line 221 and suction port 7B of pump device 100B. The liquefied gas passes through flow path switching device 5B while bypassing submersible pump 1B. Furthermore, the liquefied gas passing through flow path switching device 5B is introduced into suction container 2C through inlet line 222 and suction port 7C of pump device 100C. The liquefied gas passes through flow path switching device 5C while bypassing submersible pump 1C. The liquefied gas is discharged through the discharge port 8C of the pump unit 100C.

[0181] In this way, the flow path switching devices 5A, 5B, and 5C can prevent liquefied gas and evaporated gas from passing through the submersible pumps 1A, 1B, and 1C when they are stopped from operation during cooling. Therefore, the impellers of the submersible pumps 1A, 1B, and 1C will not rotate when they are stopped, which prevents damage to the sliding parts such as the bearings of the submersible pumps 1A, 1B, and 1C.

[0182] Figure 33 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units 100A, 100B, and 100C connected in parallel. Unless otherwise specified, the configuration and operation of this embodiment are referenced. Figures 27 to 29 The implementation methods described are the same, so repeated descriptions are omitted.

[0183] The pump system of this embodiment includes: an inlet line 211 connected to the discharge port 25A of the liquefied gas storage tank 105 and the suction container 2A; an inlet line 212 connected to the discharge port 8A of the suction container 2A and the discharge port 25B of the suction container 2B; and an inlet line 231 connected to the discharge port 8A of the suction container 2A and the discharge port 25C of the suction container 2C. The pump system also includes an inlet valve 215 installed on the inlet line 211, an inlet valve 216 installed on the inlet line 212, and an inlet valve 232 installed on the inlet line 231.

[0184] When inlet valve 215 is opened, the discharge port 25A of suction container 2A is connected to liquefied gas storage tank 105 via inlet line 211. When inlet valve 216 is opened, the discharge port 25B of suction container 2B is connected to the discharge port 8A of suction container 2A via inlet line 212. Inlet line 231 bypasses pump unit 100B and extends from discharge port 8A of suction container 2A to discharge port 25C of suction container 2C. When inlet valve 232 is opened, the discharge port 25C of suction container 2C is connected to discharge port 8A of suction container 2A via inlet line 231. Figure 33 As shown, during the operation of submersible pumps 1A, 1B, and 1C, inlet valves 215, 216, and 232 are closed, while outlet valves 202 and 204 are open.

[0185] Figure 34 and Figure 35 It shows that it is aimed at Figure 33 The diagram illustrates one implementation of a pump system for cooling. (As shown) Figure 34 As shown, suction valves 22A, 22B, and 22C are closed, discharge valves 26A, 26B, and 26C are closed, and discharge valves 23A, 23B, and 23C are open. Inlet valves 215, 216, and 232 are open, outlet valve 202 is closed, and outlet valve 204 is open.

[0186] First, with all submersible pumps 1A, 1B, and 1C stopped, liquefied gas flows into suction container 2A through inlet line 211 and discharge port 25A. The liquefied gas evaporates upon contact with the ambient temperature suction container 2A and submersible pump 1A, forming evaporated gas. Figure 34 In the diagram, the flow of evaporating gas is represented by a dashed line.

[0187] More specifically, firstly, liquefied gas is introduced into the suction container 2A of pump unit 100A through discharge port 25A. The liquefied gas evaporates in suction container 2A, forming evaporated gas. The evaporated gas passes through flow path switching device 5A while bypassing submersible pump 1A. The evaporated gas passing through flow path switching device 5A is introduced into suction container 2B through inlet line 212 and discharge port 25B of pump unit 100B, and simultaneously into suction container 2C through inlet line 231 and discharge port 25C of pump unit 100C. The evaporated gas passes through flow path switching device 5B while bypassing submersible pump 1B. The evaporated gas passing through flow path switching device 5B is discharged from suction container 2B through discharge port 8B and discharge line 203. Similarly, the evaporated gas passes through flow path switching device 5C while bypassing submersible pump 1C. The evaporated gas passing through flow path switching device 5C is discharged from suction container 2C through discharge port 8C.

[0188] Next, as Figure 35 As shown, suction valve 22A is open and inlet valve 215 is closed. Submersible pump 1A starts. Submersible pumps 1B and 1C remain stationary. Through the operation of submersible pump 1A, liquefied gas flows into suction container 2A through suction port 7A.

[0189] Submersible pump 1A simultaneously (i.e., in parallel) delivers liquefied gas into suction containers 2B and 2C. More specifically, the liquefied gas is pressurized by the operation of submersible pump 1A and passes through flow path switching device 5A. The liquefied gas passing through flow path switching device 5A is introduced into suction container 2B via inlet line 212 and discharge port 25B of pump device 100B, and simultaneously, it is introduced into suction container 2C via inlet line 231 and discharge port 25C of pump device 100C. The liquefied gas passes through flow path switching device 5B while bypassing submersible pump 1B. The liquefied gas passing through flow path switching device 5B is discharged from suction container 2B through discharge port 8B and discharge line 203. Similarly, the liquefied gas passes through flow path switching device 5C while bypassing submersible pump 1C. The liquefied gas passing through flow path switching device 5C is discharged from suction container 2C through discharge port 8C.

[0190] In this way, the flow path switching devices 5A, 5B, and 5C can prevent liquefied gas and evaporated gas from passing through the submersible pumps 1A, 1B, and 1C when they are stopped from operation during cooling. Therefore, the impellers of the submersible pumps 1A, 1B, and 1C will not rotate when they are stopped, which prevents damage to the sliding parts such as the bearings of the submersible pumps 1A, 1B, and 1C.

[0191] Figure 36 This is a schematic diagram illustrating another embodiment of a pump system having multiple pump units 100A, 100B, and 100C connected in parallel. Unless otherwise specified, the configuration and operation of this embodiment are referenced. Figures 30 to 32 The implementation methods described are the same, so repeated descriptions are omitted.

[0192] The pump system of this embodiment includes: an inlet line 221 connected to the discharge port 8A of the suction container 2A and the suction port 7B of the suction container 2B; an inlet line 241 connected to the discharge port 8A of the suction container 2A and the suction port 7C of the suction container 2C; an inlet valve 224 installed on the inlet line 221; and an inlet valve 242 installed on the inlet line 241. The inlet valve 242 is located between the inlet valve 228 and the suction valve 22C.

[0193] When inlet valve 224 is opened, the discharge port 8A of suction container 2A is connected to the suction port 7B of suction container 2B via inlet line 221. Inlet line 241 bypasses pump assembly 100B and extends from the discharge port 8A of suction container 2A to the suction port 7C of suction container 2C. When inlet valve 242 is opened, the discharge port 8A of suction container 2A is connected to the suction port 7C of suction container 2C via inlet line 241. Figure 36 As shown, during the operation of submersible pumps 1A, 1B, and 1C, inlet valves 224 and 242 are closed, outlet valves 202 and 204 are open, and inlet valves 227 and 228 are open.

[0194] Figure 37 and Figure 38 Showing targets Figure 36 The diagram illustrates one implementation of a pump system for cooling. (As shown) Figure 37 As shown, suction valves 22A, 22B, and 22C are open, discharge valves 26A, 26B, and 26C are closed, and discharge valves 23A, 23B, and 23C are open. Inlet valves 224 and 242 and outlet valve 204 are open, while inlet valves 227 and 228 and outlet valve 202 are closed.

[0195] First, with all submersible pumps 1A, 1B, and 1C stopped, liquefied gas flows into suction container 2A through the suction port 7A of pump unit 100A. The liquefied gas comes into contact with the room-temperature suction container 2A and submersible pump 1A and evaporates, forming evaporated gas. Figure 37 In the diagram, the flow of evaporating gas is represented by a dashed line.

[0196] More specifically, firstly, liquefied gas is introduced into the suction container 2A of pump assembly 100A through suction port 7A. The liquefied gas evaporates within suction container 2A, forming evaporated gas. The evaporated gas bypasses submersible pump 1A and passes through flow path switching device 5A. The evaporated gas passing through flow path switching device 5A is introduced into suction container 2B through inlet line 221 and suction port 7B of pump assembly 100B, and simultaneously into suction container 2C through inlet line 241 and suction port 7C of pump assembly 100C. The evaporated gas bypasses submersible pump 1B and passes through flow path switching device 5B. The evaporated gas passing through flow path switching device 5B is discharged from suction container 2B through discharge port 8B and discharge line 203. Similarly, the evaporated gas bypasses submersible pump 1C and passes through flow path switching device 5C. The evaporated gas passing through flow path switching device 5C is discharged from suction container 2C through discharge port 8C.

[0197] Next, as Figure 38As shown, submersible pump 1A starts. Submersible pumps 1B and 1C remain stationary. Through the operation of submersible pump 1A, liquefied gas flows into suction container 2A through suction port 7A.

[0198] Submersible pump 1A simultaneously (i.e., in parallel) delivers liquefied gas into suction containers 2B and 2C. More specifically, the liquefied gas is pressurized by the operation of submersible pump 1A and passes through flow path switching device 5A. The liquefied gas passing through flow path switching device 5A is introduced into suction container 2B via inlet line 221 and suction port 7B of pump device 100B, and simultaneously, it is introduced into suction container 2C via inlet line 241 and suction port 7C of pump device 100C. The liquefied gas passes through flow path switching device 5B while bypassing submersible pump 1B. The liquefied gas passing through flow path switching device 5B is discharged from suction container 2B through discharge port 8B and discharge line 203. Similarly, the liquefied gas passes through flow path switching device 5C while bypassing submersible pump 1C. The liquefied gas passing through flow path switching device 5C is discharged from suction container 2C through discharge port 8C.

[0199] In this way, the flow path switching devices 5A, 5B, and 5C can prevent liquefied gas and evaporated gas from passing through the submersible pumps 1A, 1B, and 1C when they are stopped from operation during cooling. Therefore, the impellers of the submersible pumps 1A, 1B, and 1C will not rotate when they are stopped, which prevents damage to the sliding parts such as the bearings of the submersible pumps 1A, 1B, and 1C.

[0200] The above-described embodiments can also be appropriately combined. For example, during cooling, liquefied gas can be introduced into each intake container through either the intake port or the exhaust port. For example, liquefied gas is introduced into intake container 2A through intake port 7A, into intake container 2B through exhaust port 25B, and into intake container 2C through intake port 7C. In other examples, liquefied gas is introduced into intake container 2A through exhaust port 25A, into intake container 2B through intake port 7B, and into intake container 2C through intake port 7C.

[0201] Figure 39 This is a cross-sectional view showing another embodiment of the flow path switching device 5. Unless otherwise specified, the configuration and operation of this embodiment are referenced. Figure 2 and Figure 3 The implementation methods described are the same, therefore repeated descriptions are omitted. For example... Figure 39As shown, the flow path structure 45 includes a bypass flow path 55 that connects the pump-side flow path 41 and the outlet flow path 43. The cross-sectional area of ​​the bypass flow path 55 is smaller than the cross-sectional area of ​​the pump-side flow path 41. More specifically, the cross-sectional area of ​​the bypass flow path 55 is such that, when the valve core 47 closes the pump-side flow path 41 and the fluid (liquefied gas or evaporated gas) flows in the submersible pump 1 and the bypass flow path 55, the impeller 15 of the submersible pump 1 (refer to...) Figure 1 It will not rotate due to the flow of the aforementioned fluid.

[0202] Bypass path 55 can be Figure 39 The through-hole shown can also be a groove formed on the valve seat 51. Multiple bypass flow paths 55 can be provided as long as the fluid does not cause the impeller 15 to rotate. According to this embodiment, during cooling, liquefied gas can be introduced into the interior of the submersible pump 1 along the flow path. As a result, cooling of the submersible pump 1 can be completed in a shorter time. In particular, when the bypass flow path 55 introduces liquefied gas into the suction container 2 during cooling, the liquid level difference between the interior and exterior of the submersible pump 1 can be eliminated, reducing the stress generated within the submersible pump 1 due to the temperature difference between the interior and exterior of the submersible pump 1.

[0203] Reference Figure 39 The flow path switching device 5 described can also be applied to the reference. Figures 4 to 38 The flow path switching devices 5, 5A to 5F in the described implementation.

[0204] Figure 40 This is a cross-sectional view showing another embodiment of the flow path switching device 5. Unless otherwise specified, the configuration and operation of this embodiment are referenced. Figure 2 and Figure 3 The implementation methods described are the same, therefore repeated descriptions are omitted. For example... Figure 40 As shown, the valve core 47 has a through hole 57 that connects the pump-side flow path 41 and the outflow path 43. The through hole 57 extends from the pump side of the valve core 47 to the reverse pump side. The cross-sectional area of ​​the through hole 57 is smaller than the cross-sectional area of ​​the pump-side flow path 41. More specifically, the cross-sectional area of ​​the through hole 57 is such that when the valve core 47 closes the pump-side flow path 41 and the fluid (liquefied gas or evaporated gas) flows in the submersible pump 1 and the through hole 57, the impeller 15 of the submersible pump 1 ( Figure 1 It will not rotate due to the flow of the aforementioned fluid.

[0205] As long as the fluid does not cause the impeller 15 to rotate, multiple through holes 57 can be provided on the valve core 47. According to this embodiment, during cooling, liquefied gas can be introduced into the interior of the submersible pump 1 along the ground. As a result, the cooling of the submersible pump 1 can be completed in a shorter time. In particular, when liquefied gas is introduced into the suction container 2 during cooling, the through holes 57 can eliminate the liquid level difference between the interior and exterior of the submersible pump 1, reducing the stress generated in the submersible pump 1 due to the temperature difference between the interior and exterior of the submersible pump 1.

[0206] Reference Figure 40 The flow path switching device 5 described can also be applied to the reference. Figures 4 to 38 The flow path switching devices 5, 5A to 5F in the described implementation.

[0207] The above embodiments are described to enable those skilled in the art to implement the invention. Those skilled in the art will naturally be able to implement various modifications of the above embodiments, and the technical concept of the invention can also be applied to other embodiments. Therefore, the invention is not limited to the described embodiments, but should be interpreted as being based on the widest scope of the technical concept defined by the claims.

[0208] Industrial availability

[0209] This invention relates to a cooling method for submersible pumps used for conveying liquefied gases such as liquid hydrogen, liquid nitrogen, liquid ammonia, liquefied natural gas, liquefied ethylene gas, and liquefied petroleum gas. Explanation of reference numerals in the attached figures

[0210] 1, 1A, 1B, 1C, 1D, 1E, 1F Submersible Pumps

[0211] 2. 2A, 2B, 2C, 2D, 2E, 2F Inhalation Containers

[0212] 3 suction port

[0213] 4-outlet

[0214] 5. 5A, 5B, 5C, 5D, 5E, 5F Flow path switching devices

[0215] 7, 7A, 7B, 7C, 7D, 7E, 7F intake ports

[0216] Discharge ports 8, 8A, 8B, 8C, 8D, 8E, and 8F

[0217] 9-motor rotor

[0218] 10 motor stators

[0219] 11 electric motors

[0220] 12 rotating axes

[0221] 13 Motor Housing

[0222] 14 bearings

[0223] 15 impellers

[0224] 16 Pump Housing

[0225] 17Discharge flow path

[0226] Suction valves 22, 22A, 22B, 22C, 22D, 22E, 22F

[0227] Discharge valves 23, 23A, 23B, 23C, 23D, 23E, and 23F

[0228] 25, 25A, 25B, 25C, 25D, 25E, 25F emission ports

[0229] 26, 26A, 26B, 26C, 26D, 26E, 26F discharge valves

[0230] 31 Exhaust Pipe

[0231] 32 air valve

[0232] Suction lines 34, 35, and 36

[0233] 41 Pump-side flow path

[0234] 42 Container Side Flow Path

[0235] 43 outflow path

[0236] 45 Flow Path Structure

[0237] 47 valve core

[0238] 50 springs

[0239] 51 valve seat

[0240] 55 Bypass Flow Path

[0241] 57 through hole

[0242] Pump units 100, 100A, 100B, 100C, 100D, 100E, 100F

[0243] 105 Liquefied Gas Storage Tank

[0244] Pipelines 107, 108, 109, and 110

[0245] 114 and 115 connecting valves

[0246] 121, 122, 123 Inlet Pipes

[0247] 125, 126, 127 Inlet Valves

[0248] 131, 133 outflow pipelines

[0249] 132, 134 Outflow Valves

[0250] 141, 142, 143 Inlet Pipelines

[0251] 145, 146, 147 Inlet valves

[0252] 151, 152 connecting valves

[0253] 161, 163 outflow pipelines

[0254] 162, 164 Outflow Valves

[0255] 171, 172, 173 Inlet Pipelines

[0256] 176, 177, 178 Inlet valves

[0257] 181 inlet line

[0258] 182 Inlet Valve

[0259] 191 inlet line

[0260] 192 Inlet Valve

[0261] 201, 203 discharge pipelines

[0262] 202, 204 outlet valves

[0263] 211, 212, 213 Inlet Pipelines

[0264] 215, 216, 217 Inlet Valves

[0265] 221, 222 Inlet Pipelines

[0266] 224, 225 Inlet Valves

[0267] 227, 228 Inlet Valves

[0268] 231 Inlet Pipeline

[0269] 232 Inlet Valve

[0270] 241 Inlet Pipeline

[0271] 242 Inlet valve.

Claims

1. A cooling method comprising cooling a plurality of submersible pumps, each comprising at least a first pump assembly and a second pump assembly interconnected, with a liquefied gas, wherein the cooling method is characterized in that, The liquefied gas is simultaneously introduced into the first suction container of the first pump device and the second suction container of the second pump device via the first and second inlet lines extending from the liquefied gas storage tank. While allowing the liquefied gas to bypass the first submersible pump in the first intake container, the liquefied gas is also allowed to pass through the first flow path switching device in the first intake container; and while allowing the liquefied gas to bypass the second submersible pump in the second intake container, the liquefied gas is also allowed to pass through the second flow path switching device in the second intake container. The liquefied gas is discharged from the first intake container and the second intake container through the first flow path switching device and the second flow path switching device.

2. The cooling method according to claim 1, characterized in that, The first flow path switching device and the second flow path switching device each include: The flow path structure includes a pump-side flow path, a container-side flow path, and an outlet flow path; and A valve core, disposed within the flow path structure, selectively connects the outflow path to either the pump-side flow path or the container-side flow path. The pump-side flow path is connected to the corresponding discharge port of the submersible pump. The container-side flow path is connected to the interior of the corresponding suction container. The outflow path is connected to the discharge port of the corresponding inhalation container.

3. The cooling method according to claim 2, characterized in that, The first flow path switching device and the second flow path switching device each further include a spring for pressing the valve core against the flow path structure to close the pump-side flow path.

4. The cooling method according to claim 1, characterized in that, The liquefied gas is introduced into the first and second inlet containers simultaneously through the first and second inlet pipelines and through the discharge ports of the first and second inlet containers.

5. The cooling method according to claim 1, characterized in that, The liquefied gas is introduced into the first and second inhalation containers simultaneously through the first and second inhalation containers via the first and second inhalation lines and through the inhalation ports of the first and second inhalation containers.

6. The cooling method according to claim 1, characterized in that, The first pump device and the second pump device are connected in series.

7. The cooling method according to claim 1, characterized in that, The first pump device and the second pump device are connected in parallel.

8. A cooling method comprising cooling a plurality of submersible pumps, each comprising at least a first pump assembly and a second pump assembly interconnected, with a liquefied gas, wherein the cooling method is characterized in that, The liquefied gas is introduced into the first suction container of the first pump device. While allowing the evaporated gas generated from the liquefied gas to bypass the first submersible pump within the first suction container, the evaporated gas is also allowed to pass through the first flow path switching device within the first suction container. The evaporated gas is introduced from the first suction container into the second suction container of the second pump device. The first submersible pump is started, drawing liquefied gas from the first suction container into the second suction container. While allowing the liquefied gas to bypass the second submersible pump inside the second suction container, the liquefied gas is also allowed to pass through the second flow path switching device inside the second suction container.

9. The cooling method according to claim 8, characterized in that, The first flow path switching device and the second flow path switching device each include: The flow path structure includes a pump-side flow path, a container-side flow path, and an outlet flow path; and A valve core, disposed within the flow path structure, selectively connects the outflow path to either the pump-side flow path or the container-side flow path. The pump-side flow path is connected to the corresponding discharge port of the submersible pump. The container-side flow path is connected to the interior of the corresponding suction container. The outflow path is connected to the discharge port of the corresponding inhalation container.

10. The cooling method according to claim 9, characterized in that, The first flow path switching device and the second flow path switching device each further include a spring for pressing the valve core against the flow path structure to close the pump-side flow path.

11. The cooling method according to claim 8, characterized in that, By starting the first submersible pump, the liquefied gas is introduced from the first suction container into the second suction container through the discharge port of the second suction container.

12. The cooling method according to claim 8, characterized in that, By starting the first submersible pump, the liquefied gas is introduced from the first suction container into the second suction container through the suction port of the second suction container.

13. The cooling method according to claim 8, characterized in that, The plurality of pump units further includes a third pump unit connected to the first pump unit and the second pump unit. The third pump device has the same configuration as the first pump device and the second pump device. The method also includes the following processing: The evaporated gas is introduced from the second suction container into the third suction container of the third pump device. After the first submersible pump starts operating, the liquefied gas is introduced from the second suction container into the third suction container. While allowing the liquefied gas to bypass the third submersible pump inside the third suction container, the liquefied gas is also allowed to pass through the third flow path switching device inside the third suction container.

14. The cooling method according to claim 13, characterized in that, The first pump device, the second pump device, and the third pump device are connected in series.

15. The cooling method according to claim 13, characterized in that, The first pump device, the second pump device, and the third pump device are connected in parallel.

16. The cooling method according to claim 8, characterized in that, The plurality of pump units further includes a third pump unit connected to the first pump unit and the second pump unit. The third pump device has the same configuration as the first pump device and the second pump device. The method further includes a process of simultaneously introducing the evaporated gas from the first suction container into both the second suction container of the second pump device and the third suction container of the third pump device. In the method, The first submersible pump is started, simultaneously introducing liquefied gas from the first suction container into the second and third suction containers. While allowing the liquefied gas to bypass the second submersible pump, the liquefied gas is also allowed to pass through the second flow path switching device. Simultaneously, the liquefied gas is allowed to bypass the third submersible pump within the third suction container, and simultaneously, the liquefied gas is allowed to pass through the third flow path switching device within the third suction container. The liquefied gas is simultaneously discharged from the second intake container and the third intake container through the second flow path switching device and the third flow path switching device.

17. The cooling method according to claim 16, characterized in that, The first pump device, the second pump device, and the third pump device are connected in series.

18. The cooling method according to claim 16, characterized in that, The first pump device, the second pump device, and the third pump device are connected in parallel.

19. The cooling method according to claim 8, characterized in that, The first pump device and the second pump device are connected in series.

20. The cooling method according to claim 8, characterized in that, The first pump device and the second pump device are connected in parallel.

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