Method for starting and stopping pump device connected in series
By setting up a flow path switching device in the suction container of the submersible pump, the liquefied gas bypasses the submersible pump that stops the operation, the damage caused by forced rotation of the impeller when the series-connected pump device is started or stopped is solved, and the bearing is prevented The effect of damage.
Patent Information
- Application Number
- CN202380040230.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-05-26
- Filing Date
- 2023-05-15
- Publication Date
- 2024-12-24
AI Technical Summary
When the series-connected submersible pump device is started or stopped, the impeller of the stopped pump is forced to rotate due to the flow of liquefied gas, resulting in damage to the sliding parts such as the bearing, especially the unintentional rotation caused by the low viscosity liquefied gas increases wear.
By setting a flow path switching device in the suction container of the submersible pump, the liquefied gas bypasses the operation stops when starting or stops, the valve core and the flow path structure are used to achieve selective communication of the liquefied gas to avoid liquefaction Air flows through a submersible pump with a stop in operation.
It effectively prevents the impeller rotation of the submersible pump impeller during operation, avoids damage to the sliding parts such as bearings, and extends the service life of the equipment.
Smart Images
Figure CN119183503A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a starting method and a stopping method for a submersible pump used for transporting liquefied gases such as liquid hydrogen, liquid nitrogen, liquid ammonia, liquefied natural gas, liquefied ethylene gas, and liquefied petroleum gas, and in particular to a technology for starting and stopping other submersible pumps while preventing the rotation of the impeller of a submersible pump that is stopped. Background Art
[0002] Natural gas is widely used in thermal power generation and chemical raw materials. In addition, hydrogen is expected to be an energy source that does not produce carbon dioxide, which is the cause of global warming. The use of hydrogen as an energy source includes fuel cells and turbine power generation. Natural gas and hydrogen are in a gaseous state at room temperature, so in order to achieve their storage and transportation, natural gas and hydrogen are cooled and liquefied. Liquefied gases such as liquefied natural gas (LNG) and liquid hydrogen are temporarily stored in liquefied gas storage tanks and then transferred to power plants and factories by pumps.
[0003] Fig.11 5 is a schematic diagram showing a conventional example of a pump device for drawing liquefied gas. The pump 500 is disposed in a vertical suction container 505 connected to a liquefied gas storage tank (not shown) storing liquefied gas. The liquefied gas is introduced into the suction container 505 through the suction port 501, and the suction container 505 is filled with the liquefied gas. The pump 500 is entirely immersed in the liquefied gas. Therefore, the pump 500 is a submersible pump capable of operating in liquefied gas. When the pump 500 is operating, the liquefied gas is discharged through the discharge port 502 by the pump 500. During the operation of the pump 500, a portion of the liquefied gas in the suction container 505 is vaporized and becomes gas, and the gas is discharged from the suction container 505 through the ventilation line 503.
[0004] In order to pressurize the liquefied gas to the required pressure on the demand side, such as Fig.12 As shown, there is a case where a plurality of pump devices are connected in series. The liquefied gas is pressurized sequentially by the pumps 500 of the plurality of pump devices. When the plurality of pump devices are started, they are started sequentially from the pump 500 on the upstream side, and when they are stopped, they are stopped sequentially from the pump 500 on the downstream side.
[0005] Prior art literature
[0006] Patent Literature
[0007] Patent Document 1: Japanese Utility Model Publication No. 59-159795
[0008] Patent Document 2: Japanese Utility Model Publication No. 62-031680 Summary of the invention
[0009] However, when the pump devices connected in series are started or stopped in sequence, the following problem occurs: that is, when the first pump 500 is started, a flow of liquefied gas is generated in the stopped pump 500. As a result, the impeller of the stopped pump 500 is forced to rotate, causing damage to sliding parts such as bearings.
[0010] When the pump 500 is running, since the liquefied gas is pressurized by the rotation of the impeller, the thrust balance mechanism disposed in the pump 500 functions and does not impose excessive load on the sliding parts such as the bearings. However, when the pump 500 is stopped, the thrust balance mechanism does not function, and the liquefied gas sent from other pumps 500 forces the impeller to rotate, resulting in damage to the sliding parts such as the bearings. In particular, the liquefied gas has a low viscosity, and the sliding parts such as the bearings are easily worn due to the unintentional rotation of the impeller. In addition, when the pump 500 on the downstream side is stopped, the same situation occurs because the pump 500 on the upstream side is still in operation. The same problem also occurs when the pump 500 suddenly stops due to a failure of the pump 500.
[0011] Therefore, the present invention provides a method of starting and stopping other submersible pumps while preventing the rotation of the impeller of a submersible pump that is stopped among a plurality of submersible pumps connected in series.
[0012] In one scheme, a method is provided for starting a plurality of pump devices including at least a first pump device and a second pump device connected in series, wherein a first submersible pump disposed in a first suction container of the first pump device is started, liquefied gas is transferred to a second suction container of the second pump device through a first flow path switching device in the first suction container, the liquefied gas is allowed to bypass a second submersible pump disposed in the second suction container, and the liquefied gas is allowed to pass through a second flow path switching device in the second suction container, and then the second submersible pump is started.
[0013] In one embodiment, 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 outflow flow path; and a valve core, which is arranged in the flow path structure so that the outflow flow path is selectively connected to one of the pump side flow path and 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, and the outflow flow path is connected to the corresponding discharge port of the suction container.
[0014] In one scheme, a method is provided for stopping the operation of multiple pump devices including at least a first pump device and a second pump device connected in series, wherein when a first submersible pump arranged in a first suction container of the above-mentioned first pump device is used to transfer liquefied gas to a second suction container of the above-mentioned second pump device through a first flow path switching device in the above-mentioned first suction container, the operation of the second submersible pump arranged in the above-mentioned second suction container is stopped, the above-mentioned liquefied gas is bypassed by the above-mentioned second submersible pump, and the above-mentioned liquefied gas is passed through the second flow path switching device in the above-mentioned second suction container, and then the operation of the above-mentioned first submersible pump is stopped.
[0015] In one embodiment, 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 outflow flow path; and a valve core arranged in the flow path structure so that the outflow flow path is selectively connected to one of the pump side flow path and 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, and the outflow flow path is connected to the corresponding discharge port of the suction container.
[0016] Effects of the Invention
[0017] When the submersible pump is started or stopped, the flow path switching device can make the liquefied gas bypass the submersible pump in operation. Therefore, the impeller of the submersible pump in operation does not rotate, and as a result, the sliding parts such as the bearings of the submersible pump can be prevented from being damaged. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 This is a diagram showing one embodiment of a pump device for transferring liquefied gas.
[0019] Figure 2 It is a cross-sectional view showing one embodiment of the detailed structure of the flow path switching device.
[0020] Figure 3 Shows the status of the flow path switching device when the submersible pump is operating.
[0021] Figure 4 This is a schematic diagram showing one embodiment of a pump system including a plurality of pump devices connected in series.
[0022] Figure 5 It is an explanation Figure 4 FIG. 1 is a diagram of one embodiment of a method for sequentially starting a plurality of submersible pumps.
[0023] Figure 6 It is an explanation Figure 4 FIG. 1 is a diagram of the above-described embodiment of a method for sequentially starting a plurality of submersible pumps.
[0024] Figure 7 It is an explanation Figure 4 FIG. 1 is a diagram of one embodiment of a method for sequentially stopping the operation of a plurality of submersible pumps.
[0025] Figure 8 It is an explanation Figure 4 The diagram of the above embodiment of the method of sequentially stopping the operation of multiple submersible pumps is shown.
[0026] Fig. 9 This is a schematic diagram showing another embodiment of a pump system including a plurality of pump devices connected in series.
[0027] Fig.10 This is a schematic diagram showing still another embodiment of a pump system including a plurality of pump devices connected in series.
[0028] Fig.11 This is a schematic diagram showing a conventional example of a pump device for pumping liquefied gas.
[0029] Fig.12 This is a schematic diagram showing an example of a plurality of pump devices connected in series. DETAILED DESCRIPTION
[0030] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 FIG. 1 is a diagram showing an embodiment of a pump device for transferring liquefied gas. Figure 1 Examples of liquefied gas transferred by the pump device 100 include liquid hydrogen, liquid nitrogen, liquid ammonia, liquefied natural gas, liquefied ethylene gas, and liquefied petroleum gas.
[0031] like Figure 1 As shown, the pump device 100 includes a submersible pump 1 for transferring liquefied gas, a suction container 2 in which the submersible pump 1 is accommodated, and a flow path switching device 5 for preventing the rotation of the impeller 15 of the submersible pump 1 during operation stop. The suction container 2 has a suction port 7 and a discharge port 8. The liquefied gas is introduced into the suction container 2 through the suction port 7, and the suction container 2 is filled with the liquefied gas. During the operation of the submersible pump 1, the submersible pump 1 is immersed in the liquefied gas as a whole. Therefore, the submersible pump 1 is configured to be able to operate in the liquefied gas.
[0032] The submersible pump 1 includes: a motor 11 having a motor rotor 9 and a motor stator 10; a rotating shaft 12 connected to the motor 11; a plurality of bearings 14 that rotatably support the rotating shaft 12; an impeller 15 fixed to the rotating shaft 12; and a pump housing 16 that accommodates the impeller 15. The flow path switching device 5 is arranged in 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 structure of the flow path switching device 5 will be described later.
[0033] When electric power is supplied to the motor 11 through a power cable (not shown), the motor 11 rotates the rotating shaft 12 and the impeller 15 integrally. As the impeller 15 rotates, the liquefied gas is sucked into the submersible pump 1 from the suction port 3, and is ejected into the flow path switching device 5 through the ejection flow path 17 and the ejection port 4. Furthermore, the liquefied gas passes through the flow path switching device 5 and is discharged through the ejection port 8 of the suction container 2.
[0034] The suction port 7 is connected to a suction valve 22, and the discharge port 8 is connected to a discharge valve 23. A discharge pipe 25 is connected to the bottom of the suction container 2, and a discharge valve 26 is connected to the discharge pipe 25. The suction port 7 is provided on the side wall of the suction container 2, and is located at a higher position than the bottom of the suction container 2. The discharge port 8 is provided at the upper part of the suction container 2, and is located at a higher position than the suction port 7. During the operation of the submersible pump 1, the suction valve 22 and the discharge valve 23 are opened, and the discharge valve 26 is closed.
[0035] A ventilation line 31 is connected to the upper part of the suction container 2. During the operation of the submersible pump 1, a part of the liquefied gas is vaporized due to the heat of the submersible pump 1 and becomes gas, and the gas is discharged from the suction container 2 through the ventilation line 31. A ventilation valve 32 is connected to the ventilation line 31. In one embodiment, the gas can also be introduced into a gas treatment device (not shown) through the ventilation line 31. The gas treatment device is a device that treats the gas (such as natural gas or hydrogen) obtained by gasification of liquefied gas. Examples of gas treatment devices include gas incineration devices (combustion devices), chemical gas treatment devices, gas adsorption devices, etc.
[0036] Figure 2 1 is a cross-sectional view showing a detailed structure of the flow path switching device 5 according to an embodiment of the present invention. Figure 2As shown, the flow path switching device 5 includes a flow path structure 45, which has a pump side flow path 41, a container side flow path 42 and an outflow flow path 43, and includes a valve core 47 arranged in the flow path structure 45. The pump side flow path 41 is connected to the discharge port 4 of the submersible pump 1, the container side flow path 42 is connected to the inside of the suction container 2, and the outflow flow path 43 is connected to the discharge port 8 of the suction container 2. The valve core 47 is configured to selectively connect the outflow flow path 43 to one of the pump side flow path 41 and the container side flow path 42. The structure of the flow path switching device 5 is not limited as long as it can perform its intended function. Figure 2 The embodiment shown.
[0037] Figure 2 The state of the flow path switching device 5 when the submersible pump 1 is not in operation is shown. The valve core 47 is pressed against the flow path structure 45 by the spring 50 to close 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, and the valve core 47 is pressed against the valve seat 51 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 is connected to the outflow flow path 43. The container side flow path 42 opens in the suction container 2 and is connected to the suction port 7 through the interior of the suction container 2.
[0038] Figure 3 The state of the flow path switching device 5 when the submersible pump 1 is in operation is shown. When the submersible pump 1 is in operation, liquefied gas is ejected from the discharge port 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 moves the valve core 47 against the force of the spring 50, opens the pump side flow path 41, and closes the container side flow path 42 by the valve core 47. As a result, the pump side flow path 41 is connected to the outflow flow path 43.
[0039] When the operation of the submersible pump 1 stops, the valve core 47 is pressed against the valve seat 51 by the spring 50. As a result, Figure 2 As shown, the pump side flow path 41 is closed, and the container side flow path 42 is communicated with the outflow flow path 43. In this way, the flow path switching device 5 of the present embodiment operates only by the spring 50 and the flow of the liquefied gas.
[0040] In order to pressurize the liquefied gas to a pressure required by the demand side, a plurality of pump devices 100 may be connected in series. Figure 4 1 is a schematic diagram showing an embodiment of a pump system including a plurality of pump devices 100A, 100B, and 100C connected in series. Figure 4 In the embodiment, the plurality of pump devices 100A, 100B, 100C have the same Figures 1 to 6In the following description, the submersible pump, suction container, and flow path switching device of the pump device 100A are respectively referred to as the submersible pump 1A, the suction container 2A, and the flow path switching device 5A; the submersible pump, suction container, and flow path switching device of the pump device 100B are respectively referred to as the submersible pump 1B, the suction container 2B, and the flow path switching device 5B; and the submersible pump, suction container, and flow path switching device of the pump device 100C are respectively referred to as the submersible pump 1C, the suction container 2C, and the flow path switching device 5C.
[0041] The pump device 100A is arranged upstream of the pump device 100B, and the pump device 100B is arranged upstream of the pump device 100C. The suction port 7 of the pump device 100A is connected to the liquefied gas storage tank 105 in which the liquefied gas is stored. The pump device 100A is connected in series with the pump device 100B through the connecting pipe 107, and the pump device 100B is connected in series with the pump device 100C through the connecting pipe 108. More specifically, the discharge port 8 of the pump device 100A is connected to the suction port 7 of the pump device 100B through the connecting pipe 107, and the discharge port 8 of the pump device 100B is connected to the suction port 7 of the pump device 100C through the connecting pipe 108.
[0042] The submersible pumps 1A, 1B, and 1C are connected in series in the order of submersible pump 1A, submersible pump 1B, and submersible pump 1C. The liquefied gas is pressurized in sequence by these submersible pumps 1A, 1B, and 1C. When the submersible pumps 1A, 1B, and 1C are in operation and the flow path switching devices 5A, 5B, and 5C are in Figure 3 Status shown.
[0043] Next, Figure 4 An embodiment of a method for starting the submersible pumps 1A, 1B, and 1C connected in series as shown will be described. The submersible pumps 1A, 1B, and 1C are started sequentially from the upstream side. That is, the submersible pump 1A is started first, the submersible pump 1B is started next, and the submersible pump 1C is started last.
[0044] Figure 5 This is a diagram for explaining the state in which the submersible pump 1A is started and the submersible pumps 1B and 1C are stopped. When the submersible pump 1A is started, the liquefied gas is transferred to the suction container 2B of the pump device 100B through the flow path switching device 5A by the submersible pump 1A. The submersible pump 1A is in operation and the flow path switching device 5A is in the state in which the liquefied gas is transferred. Figure 3 Status shown.
[0045] At this stage, since the submersible pump 1B is stopped, the flow path switching device 5B is in Figure 2Therefore, the liquefied gas bypasses the submersible pump 1B (that is, the liquefied gas does not flow in the submersible pump 1B) while passing through the flow path switching device 5B. The liquefied gas is further transferred from the pump device 100B to the suction container 2C of the pump device 100C. Since the submersible pump 1C is also stopped, the flow path switching device 5C is in Figure 2 Therefore, the liquefied gas bypasses the submersible pump 1C (that is, the liquefied gas does not flow in the submersible pump 1C) while passing through the flow path switching device 5C.
[0046] Next, the submersible pump 1B is started. Figure 6 This is a diagram for explaining a state in which the submersible pump 1B is started while the submersible pump 1A is in operation and the submersible pump 1C is stopped. When the submersible pump 1B is started, the liquefied gas is transferred to the suction container 2C of the pump device 100C by the submersible pump 1B through the flow path switching device 5B. The submersible pump 1B is in operation and the flow path switching device 5B is in the state when transferring the liquefied gas. Figure 3 Status shown.
[0047] At this stage, since the submersible pump 1C is still in operation, the flow path switching device 5C is in Figure 2 Therefore, the liquefied gas bypasses the submersible pump 1C (that is, the liquefied gas does not flow in the submersible pump 1C) while passing through the flow path switching device 5C.
[0048] Next, the submersible pump 1C is started. When the submersible pump 1C is started, the submersible pumps 1A and 1B are in operation. The state in which the submersible pumps 1A, 1B, and 1C are all in operation is shown in FIG. Figure 4 In this manner, the submersible pumps 1A, 1B, and 1C are started in sequence from the upstream side.
[0049] When the submersible pumps 1A, 1B, and 1C are started, the flow path switching device can make the liquefied gas bypass the submersible pumps that are stopped. Therefore, the impellers of the submersible pumps that are stopped do not rotate, and as a result, the sliding parts of the submersible pumps, such as bearings, can be prevented from being damaged.
[0050] Next, Figure 4 An embodiment of a method for stopping the operation of the submersible pumps 1A, 1B, and 1C connected in series as shown is described. The operation of the submersible pumps 1A, 1B, and 1C is stopped in sequence from the downstream side. That is, the operation of the submersible pump 1C is stopped first, then the operation of the submersible pump 1B is stopped, and finally the operation of the submersible pump 1A is stopped.
[0051] Figure 7 This is a diagram for explaining a state in which the submersible pump 1C is stopped and the submersible pumps 1A and 1B are in operation. As a result of the submersible pump 1C being stopped, the flow path switching device 5C becomes Figure 2Therefore, the liquefied gas bypasses the submersible pump 1C (that is, the liquefied gas does not flow in the submersible pump 1C) while passing through the flow path switching device 5C.
[0052] At this stage, the submersible pumps 1A and 1B are in operation. Therefore, the liquefied gas is transferred to the suction container 2B of the pump device 100B by the submersible pump 1A through the flow switching device 5A, and further, the liquefied gas is transferred to the suction container 2C of the pump device 100C by the submersible pump 1B through the flow switching device 5B. The submersible pumps 1A and 1B are in operation and the flow switching devices 5A and 5B are in the state of transferring the liquefied gas. Figure 3 Status shown.
[0053] Next, the submersible pump 1B is stopped. Figure 8 1A is a diagram for explaining a state in which the submersible pump 1A is in operation, the submersible pump 1C is in operation stop, and the submersible pump 1B is stopped. As a result of the submersible pump 1B being stopped, the flow path switching device 5B becomes Figure 2 Therefore, the liquefied gas bypasses the submersible pump 1B (that is, the liquefied gas does not flow in the submersible pump 1B) while passing through the flow path switching device 5B.
[0054] At this stage, since the submersible pump 1A is still in operation, the flow path switching device 5A is in Figure 3 Therefore, the liquefied gas is transferred to the suction container 2B of the pump device 100B by the submersible pump 1A through the flow path switching device 5A.
[0055] Next, the submersible pump 1A is stopped. When the submersible pump 1A is stopped, the submersible pumps 1B and 1C are stopped. In this way, the submersible pumps 1A, 1B, and 1C are stopped in order from the downstream side.
[0056] When the submersible pumps 1A, 1B, and 1C are stopped, the flow path switching device can make the liquefied gas bypass the submersible pumps during the shutdown. Therefore, the impellers of the submersible pumps during the shutdown do not rotate, and as a result, the sliding parts of the submersible pumps, such as bearings, can be prevented from being damaged.
[0057] Figures 4 to 8 The pump system of the embodiment shown has three pump devices 100A, 100B, and 100C connected in series, but the number of pump devices is not limited to this embodiment. In one embodiment, the pump system may have only two pump devices connected in series, or may have four or more pump devices connected in series. The multiple submersible pumps connected in series are started and stopped in the same manner as in the above-mentioned embodiment.
[0058] Fig. 9Schematic diagram showing another embodiment of a pump system having a plurality of pump devices connected in series. Figure 7 The described implementation modes are the same, so repeated descriptions thereof are omitted. Fig. 9 The pump system of the illustrated embodiment includes pump devices 100D, 100E, and 100F connected in series in addition to the pump devices 100A, 100B, and 100C connected in series.
[0059] The pump device 100D includes a suction container 2D and a submersible pump 1D and a flow switching device 5D arranged in the suction container 2D. The pump device 100E includes a suction container 2E and a submersible pump 1E and a flow switching device 5E arranged in the suction container 2E. The pump device 100F includes a suction container 2F and a submersible pump 1F and a flow switching device 5F arranged in the suction container 2F.
[0060] The pump device 100D is connected in series with the pump device 100E via the communication line 109, and the pump device 100E is connected in series with the pump device 100F via the communication line 110. More specifically, the discharge port of the pump device 100D is connected to the suction port of the pump device 100E via the communication line 109, and the discharge port of the pump device 100E is connected to the suction port of the pump device 100F via the communication line 110.
[0061] The pump devices 100D, 100E, and 100F are arranged in parallel with the pump devices 100A, 100B, and 100C. The plurality of pump devices 100A, 100B, 100C, 100D, 100E, and 100F have the same Figures 1 to 3 The pump devices 100 described above have the same structure, so their repeated description is omitted. The pump devices 100A and 100D are connected to a liquefied gas storage tank 105 storing liquefied gas. Fig. 9 In the illustrated embodiment, liquefied gas is pressurized and transported by submersible pumps 1A to 1C of pump devices 100A to 100C and submersible pumps 1D to 1F of pump devices 100D to 100F which are arranged in parallel.
[0062] Submersible pumps 1D, 1E, and 1F are started in order from the upstream side similarly to submersible pumps 1A, 1B, and 1C. That is, submersible pump 1D is started first, followed by submersible pump 1E, and finally submersible pump 1F.
[0063] The submersible pumps 1D, 1E, and 1F are stopped in order from the downstream side similarly to the submersible pumps 1A, 1B, and 1C. That is, the submersible pump 1F is stopped first, followed by the submersible pump 1E, and finally the submersible pump 1D.
[0064] Fig.10Schematic diagram showing still another embodiment of a pump system having a plurality of pump devices connected in series. Fig. 9 The embodiments described are the same, so repeated descriptions are omitted. Fig.10 In the illustrated embodiment, the communication line 107 connecting the pump device 100A and the pump device 100B is connected to the communication line 109 connecting the pump device 100D and the pump device 100E via the intermediate liquid collecting section 111. In addition, the communication line 108 connecting the pump device 100B and the pump device 100C is connected to the communication line 110 connecting the pump device 100E and the pump device 100F via the intermediate liquid collecting section 112.
[0065] As in the above-mentioned embodiment, the submersible pumps 1A, 1B, 1C are started sequentially from the upstream side, and the submersible pumps 1D, 1E, 1F are also started sequentially from the upstream side. The submersible pumps 1A, 1B, 1C are stopped sequentially from the downstream side, and the submersible pumps 1D, 1E, 1F are also stopped sequentially from the downstream side.
[0066] The pump devices 100A to 100C are also connected in series with the pump devices 100D to 100F through the intermediate liquid collecting parts 111 and 112. As a result, various flows of liquefied gas are formed, and various operations of the pump devices 100A to 100C and the pump devices 100D to 100F can be realized. For example, the operation of the pump device 100C or the pump device 100F can be stopped for maintenance or according to the required pressure on the demand side.
[0067] exist Fig. 9 and Fig.10 In the pump system shown, two rows of pump devices 100A to 100C and pump devices 100D to 100F are provided in parallel, but a plurality of pump devices in three or more rows may be provided in parallel.
[0068] The above-mentioned embodiments are recorded for the purpose of enabling persons with common knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above-mentioned embodiments are naturally implementable for those skilled in the art, and the technical concept of the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is interpreted in accordance with the maximum scope of the technical concept defined by the claims.
[0069] Industrial Applicability
[0070] The present invention can be utilized in a method for starting and stopping a submersible pump used in the transfer of liquefied gases such as liquid hydrogen, liquid nitrogen, liquid ammonia, liquefied natural gas, liquefied ethylene gas, and liquefied petroleum gas.
[0071] Description of Reference Numerals
[0072] 1, 1A, 1B, 1C, 1D, 1E, 1F Submersible pump
[0073] 2, 2A, 2B, 2C, 2D, 2E, 2F Inhalation container
[0074] 3 suction port
[0075] 4 Spout
[0076] 5, 5A, 5B, 5C, 5D, 5E, 5F Flow path switching device
[0077] 7 Intake port
[0078] 8 Discharge port
[0079] 9 Motor rotor
[0080] 10 Motor stator
[0081] 11 Electric Motor
[0082] 12 Rotation axis
[0083] 14 Bearings
[0084] 15 Impeller
[0085] 16 Pump housing
[0086] 17 Discharge flow path
[0087] 22 Suction valve
[0088] 23. Discharge valve
[0089] 25 Discharge pipeline
[0090] 26 Relief valve
[0091] 31 Ventilation line
[0092] 32 Ventilation valve
[0093] 41 Pump side flow path
[0094] 42 Container side flow path
[0095] 43 Outflow path
[0096] 45 Flow path structure
[0097] 47 Valve core
[0098] 50 Spring
[0099] 51 Valve seat
[0100] 100, 100A, 100B, 100C, 100D, 100E, 100F pump units
[0101] 105 Liquefied gas storage tank
[0102] 107, 108, 109, 110 connecting pipes
[0103] 111, 112 intermediate liquid collecting section.
Claims
1. A method of starting a plurality of pump devices including at least a first pump device and a second pump device connected in series, wherein: The first submersible pump disposed in the first suction container of the first pump device is started to transfer the liquefied gas to the second suction container of the second pump device through the first flow path switching device in the first suction container. The liquefied gas is caused to bypass the second submersible pump disposed in the second suction container while passing through the second flow path switching device in the second suction container. Then, The second submersible pump is started.
2. The method according to claim 1, wherein: 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 outflow flow path; and a valve core disposed in the flow path structure body, which selectively connects the outflow flow path with 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 passage communicates with the corresponding discharge port of the suction container.
3. The method according to claim 2, wherein: Each of the first flow path switching device and the second flow path switching device further includes a spring that presses the valve element against the flow path structure to close the pump-side flow path.
4. The method according to claim 1, wherein: The plurality of pump devices further include a third pump device and a fourth pump device connected in series, The third pump device and the fourth pump device are arranged in parallel with the first pump device and the second pump device. The third pump device and the fourth pump device have the same structure as the first pump device and the second pump device.
5. The method according to claim 4, wherein: The communication conduit connecting the first pump device and the second pump device is connected to the communication conduit connecting the third pump device and the fourth pump device through an intermediate liquid header.
6. A method of stopping the operation of a plurality of pump devices including at least a first pump device and a second pump device connected in series, wherein: When the liquefied gas is transferred to the second suction container of the second pump device through the first flow path switching device in the first suction container by using the first submersible pump arranged in the first suction container, the operation of the second submersible pump arranged in the second suction container is stopped. The liquefied gas is caused to bypass the second submersible pump while passing through the second flow path switching device in the second suction container, and then, The operation of the first submersible pump is stopped.
7. The method according to claim 6, wherein: 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 outflow flow path; and a valve element disposed in the flow path structure body, and selectively connecting the outflow flow path to one of the pump side flow path and 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 passage communicates with the corresponding discharge port of the suction container.
8. The method according to claim 7, wherein: Each of the first flow path switching device and the second flow path switching device further includes a spring that presses the valve element against the flow path structure to close the pump-side flow path.
9. The method according to claim 6, wherein: The plurality of pump devices further include a third pump device and a fourth pump device connected in series, The third pump device and the fourth pump device are arranged in parallel with the first pump device and the second pump device. The third pump device and the fourth pump device have the same structure as the first pump device and the second pump device.
10. The method according to claim 9, wherein: The communication conduit connecting the first pump device and the second pump device is connected to the communication conduit connecting the third pump device and the fourth pump device by an intermediate header.