Low-temperature immersed pump for engine fuel supply system of LNG (liquefied natural gas) ship and floating device

Abstract

The invention discloses a low-temperature immersed pump for an engine fuel supply system of an LNG (Liquefied Natural Gas) ship and a floating device, and relates to the technical field of immersed pumps, in particular to the low-temperature immersed pump for the engine fuel supply system of the LNG ship and the floating device. An immersed pump is fixedly arranged on a pump tower through a pump bracket; a low-temperature cable junction box is mounted on the base and connected with a low-temperature cable; the low-temperature cable is fixed in the cabin through the low-temperature cable fixing device; the low-temperature cable penetrates through a low-temperature cable deck guide pipe arranged on a deck on the top of a cabin and then is connected with the junction box through an electrical penetrating connector and a normal-temperature cable. According to the technical scheme, the problems that in the prior art, an existing LNG pump is poor in cavitation resistance; the balance capacity cannot meet the ocean swinging working condition, and under the ocean environment swinging and shaking working condition, it is difficult to ensure that the axial force of a rotor is completely balanced in a wide operation range; and a pump bracket adopts a fixed bracket, so that the pump bracket is easily damaged due to large stress under a swinging working condition.

Description

Technical Field

[0001] The present invention relates to a cryogenic submersible pump for an LNG ship and a floating device engine fuel supply system, and relates to the technical field of submersible pumps, in particular to a cryogenic submersible pump for an LNG ship and a floating device engine fuel supply system. Background Art

[0002] Currently, cryogenic pumps are required to transport cryogenic media in LNG cryogenic medium carriers and floating devices. Due to the low temperature, flammability, explosiveness, and easy vaporization of the medium, pump equipment used to transport this type of medium is required to have reliable sealing, low medium vaporization volume, and a safe, stable, and reliable structure. This type of pump is difficult to design, manufacture, and test. Therefore, at present, this type of vertical cryogenic marine submersible pump in China relies on imports, resulting in high product prices and slow service response. The localization of vertical cryogenic marine submersible pump equipment is conducive to cost control in the LNG transportation link, the expansion of the application of vertical cryogenic marine submersible pumps in the fields of propane, ethylene, and other transport ships, and the improvement of the design and manufacturing level of large-scale cryogenic submersible pumps in China.

[0003] Existing LNG pumps have poor anti-cavitation capabilities; their balancing capabilities cannot meet the requirements of ocean swing conditions. Under swing and swaying conditions in the marine environment, it is difficult to ensure that the rotor axial force is completely balanced within a wide operating range; the pump bracket adopts a fixed bracket, which is easily damaged under high stress under swing conditions.

[0004] In view of the problems existing in the above-mentioned prior art, it is very necessary to research and design a new type of cryogenic submersible pump for LNG ship and floating device engine fuel supply system, so as to overcome the problems existing in the prior art. Summary of the Invention

[0005] According to the above-mentioned prior art, the existing LNG pump has poor anti-cavitation ability; the balancing ability cannot meet the ocean swinging working conditions. Under the swinging and shaking working conditions in the ocean environment, it is difficult to ensure that the rotor axial force is completely balanced in a wide operating range; the pump bracket adopts a fixed bracket, which is easy to be damaged under the swinging working conditions. Technical problems such as the present invention provides a low-temperature submersible pump for the engine fuel supply system of LNG ships and floating devices. The present invention mainly adopts the impeller and guide shell hydraulics of a large specific speed pump and a high cavitation resistance inducer to achieve the ultra-low suction level capability of the liquid cargo pump; by setting an axial force balancing device, the problem of complete axial force balance under the overall shaking and tilting working conditions of the pump is solved; the liquid cargo pump is connected to the pump tower with a pump bracket, which can slide radially, solving the problem of different shrinkage amounts of the pump casing and bracket under low temperature conditions. The pump and pump bracket can be firmly fixed on the pump tower to prevent the submersible pump from loosening during swinging and surge.

[0006] The technical means adopted in the present invention are as follows:

[0007] A cryogenic submersible pump for an LNG ship or floating device engine fuel supply system comprises: a submersible pump, a pump bracket, a cryogenic cable, a cryogenic cable fixing device, a cryogenic cable deck conduit, an electrical penetration joint, a normal temperature cable, and a junction box;

[0008] Furthermore, the submersible pump adopts an impeller ring-less structure to prevent the retaining ring from loosening and falling due to mechanical friction during pump operation; the submersible pump is located on the upper part of the cabin bottom and is fixed to the pump tower through a pump bracket; an oblong hole is provided at the connection point, and under low temperature conditions, the pump bracket can slide radially, solving the problem of different shrinkage amounts of the pump casing and bracket under low temperature conditions, and reducing the stress caused by deformation; the pump bracket is fixed to the pump tower by bolts, and the pump and pump bracket can be firmly fixed to the pump tower.

[0009] Furthermore, a cryogenic cable junction box is installed on the upper part of the submersible pump, and the motor cable inside the submersible pump and the external cryogenic cable are connected through the cryogenic cable junction box;

[0010] Furthermore, the cryogenic cable is fixed inside the cabin by a cryogenic cable fixing device;

[0011] Furthermore, after the low-temperature cable passes through the low-temperature cable deck conduit arranged on the top deck of the cabin, it is connected to the junction box through the electrical penetration joint and the normal temperature cable.

[0012] Furthermore, the electrical through-connector adopts the gas sealing technology of metal and ceramic welding and metal and glass packaging. While transmitting electricity, it also prevents the pumped flammable and explosive media from leaking along the low-temperature cable to the junction box outside the cabin, achieving zero leakage of the media. The sealing is safer and more reliable, which improves the safety and reliability of the whole machine operation.

[0013] Furthermore, the submersible pump has a high head and adopts a multi-stage impeller structure, including: an inducer, an impeller, a middle section, a cylinder, an axial force balancing device, an outlet section, a motor housing, a shaft, a motor rotor, a motor stator, a motor end cover and a guide vane;

[0014] Furthermore, the motor end cover, the motor housing, the outlet section and the cylinder are connected in sequence by bolts to form the motor housing;

[0015] Furthermore, a bearing housing is provided inside the motor end cover, and the upper bearing is mounted on the motor housing;

[0016] Furthermore, a boss is provided on the inner circumference of the lower portion of the motor housing, and the motor stator is mounted on the boss;

[0017] Furthermore, a junction box mounting hole is designed on the side of the motor housing for installing a low-temperature cable junction box;

[0018] Furthermore, the shaft is assembled on the motor end cover and the outlet section through a bearing seat, on which the motor rotor is assembled, and the motor rotor and the motor stator form a submersible motor;

[0019] Furthermore, an axial force balancing device is installed on the outlet end and is located in the outlet section;

[0020] Furthermore, a middle section is provided inside the cylinder, forming a double-shell barrel-bag type pressure-bearing structure, which effectively improves the safety of the pump casing;

[0021] Furthermore, a plurality of guide vanes and impellers are installed inside the middle section;

[0022] Furthermore, connecting screws are provided between the middle section and the guide vanes, and between the middle sections, to prevent the middle section and the guide vanes from rotating during operation;

[0023] Furthermore, the impeller is a closed impeller structure, which consists of a front cover, middle blades and a rear cover, mounted on the shaft and rotating with the pump shaft. Due to the action of the blades, the medium rotates in the impeller and flows out at a certain speed into the outlet section;

[0024] Furthermore, the inducer is installed at the bottom end of the shaft, located below the lowest impeller; the inducer is a cylindrical equal-pitch structure, and adopts a larger inlet flow area, a smaller inlet attack angle, and a thinner blade inlet thickness, so that the speed of the medium at the inducer inlet is small, the pressure around the inducer blades is uniform, and the medium flowing out of the inducer directly enters the impeller.

[0025] Furthermore, the cryogenic cable junction box is composed of a housing and wiring terminals;

[0026] Furthermore, the connection positions of the terminal blocks, the submersible motor end cables and the cryogenic cables are located inside the cryogenic cable junction box, which protects the cable connection positions to prevent the impact of the medium in the cabin on the connectors.

[0027] Furthermore, the motor rotor is supported by two-point bearings, located at the upper and lower ends of the motor respectively. The bearings are deep groove ball bearings, and the bearings are fixed to the shaft by locking nuts; they are lubricated and cooled by low-temperature media during operation.

[0028] Furthermore, the outlet section is divided into several independent flow channels;

[0029] Furthermore, a liquid outlet pipe is provided on the outer circumference of the motor housing, and the liquid enters the liquid outlet pipe after being discharged from the outlet section;

[0030] Furthermore, a liquid outlet channel is provided inside the motor end cover, and the medium enters the outlet pipe through the liquid outlet channel;

[0031] Further, the flow channel, the liquid outlet pipe and the liquid outlet flow channel are connected;

[0032] Furthermore, the outlet section collects the liquid flowing out of the impeller and transports it to the liquid outlet channel through the flow channel and the liquid outlet pipe, converting the velocity energy of the liquid into pressure energy.

[0033] Furthermore, the outlet section features a bearing housing structure, eliminating the need for a separate bearing housing. Instead, a bearing mounting location is provided within the outlet section, where a bearing bushing is installed. The bearing is mounted on the shaft and then mounted within the outlet section via the bearing bushing. This compact outlet section structure integrates the housing, flow passage, and bearing housing, reducing pump height and weight, meeting the size and weight requirements of marine equipment.

[0034] Furthermore, the axial force balancing device includes: a balancing disc, a final stage impeller and a balancing circuit;

[0035] Furthermore, the balancing disc adopts a cone-shaped structure, the upper section area is larger than the lower section area, the balancing disc is located between the impeller rear cover and the outlet section, and the balancing disc is fixed on the outlet section;

[0036] Furthermore, the last-stage impeller is a closed impeller structure, consisting of a front cover, intermediate blades and a rear cover, assembled on the shaft and located below the balance disc; a gap is left between the last-stage impeller and the body ring on the outlet section;

[0037] Furthermore, the outlet of the final impeller is connected to the chamber of the motor housing via a balancing circuit, ensuring that the pressure inside the motor housing and at the impeller outlet is the same. The pressure differential across the balancing disc is small, resulting in high sensitivity. Under various operating conditions, the balancing disc is able to quickly balance axial forces, freeing the bearings from stress. Under various operating conditions, the balancing disc is less susceptible to wear during dynamic balancing. This axial force balancing structure exhibits minimal leakage, effectively improving pump efficiency. This axial force balancing device solves the problem of completely balancing axial forces under conditions of overall pump shaking and tilting.

[0038] Furthermore, the shaft is an integral stepped structure;

[0039] Furthermore, a keyway is machined on the shaft, and the inducer, impeller and final stage impeller are all installed on the shaft by means of keys and keyways; the shaft of the one-piece structure has no connecting shaft structure in the middle, and does not require a coupling. The structure is compact, which effectively reduces the height of the pump and improves the reliability of the pump operation. At the same time, it is suitable for installation in a compact space in a cabin.

[0040] Furthermore, the filter is installed at the suction port at the bottom of the cylinder;

[0041] Furthermore, the filter is a metal frame structure, the filter circumference and bottom surface are welded frames, the surrounding and bottom frames are covered with a filter screen, and the filter screen is a perforated plate;

[0042] Furthermore, a bolt hole is provided on the upper flange of the filter, and the upper part of the filter is connected to the cylinder through bolts.

[0043] Furthermore, the filter frame can bear the weight of the submersible pump. During temporary storage, transportation, installation, etc., the submersible pump can be supported by the filter frame and placed on a flat surface without the need for additional support tools. The filter mesh is distributed around the filter circumference and bottom surface, allowing the medium to enter the pump through the filter mesh holes. At the same time, the filter mesh can prevent large impurities from entering the pump, effectively preventing impurities in the medium from damaging the internal parts of the pump, thereby extending the maintenance cycle of the pump.

[0044] Furthermore, the filter is a half-structure, and after the pump is installed, the filter can be removed without disassembling the pump;

[0045] Furthermore, there is a support structure in the filter, which can serve as a temporary support during the pump disassembly and assembly process, allowing the pump to be placed upright.

[0046] Compared with the prior art, the present invention has the following advantages:

[0047] 1. The present invention provides a cryogenic submersible pump for an LNG carrier and a floating device engine fuel supply system. The submersible pump is fixed to a pump tower via a pump bracket. An oblong hole is provided at the connection point, allowing the pump bracket to slide radially under low-temperature conditions, thereby resolving the problem of different shrinkage amounts of the pump casing and bracket under low-temperature conditions and reducing stress caused by deformation. The pump bracket is fixed to the pump tower via bolts, allowing the pump and pump bracket to be securely fixed to the pump tower.

[0048] 2. The cryogenic submersible pump for the engine fuel supply system of LNG ships and floating devices provided by the present invention adopts a gas sealing technology of metal-ceramic welding and metal-glass packaging for the electrical through-connector. While transmitting electricity, it also prevents the pumped flammable and explosive medium from leaking along the cryogenic cable to the junction box outside the cabin, thereby achieving zero leakage of the medium, making the sealing safer and more reliable, and improving the safety and reliability of the entire machine operation.

[0049] 3. The cryogenic submersible pump for the LNG ship and floating device engine fuel supply system provided by the present invention has an outlet section structure that integrates the shell, flow channel, and bearing box into one, with a compact structure, which reduces the height of the pump body and the weight of the equipment, and is suitable for the requirements of equipment size and weight in ships.

[0050] 4. The low-temperature submersible pump for the engine fuel supply system of LNG ships and floating devices provided by the present invention has a small pressure difference at both ends of the balance plate and high sensitivity. Under various working conditions, it can quickly balance the axial force so that the bearing is not stressed; under various working conditions, the balance plate is not easily worn during the dynamic balancing process; the axial force balancing structure has a small leakage rate and can effectively improve the efficiency of the pump; the axial force balancing device solves the problem of complete axial force balance under the conditions of overall shaking and tilting of the pump.

[0051] 5. The cryogenic submersible pump for the LNG ship and floating device engine fuel supply system provided by the present invention has an integrated structure with no connecting shaft structure in the middle of the shaft, does not require a coupling, has a compact structure, effectively reduces the height of the pump, improves the reliability of the pump operation, and is suitable for installation in a compact space in the cabin.

[0052] 6. The cryogenic submersible pump for the LNG carrier and floating device engine fuel supply system provided by the present invention has a filter frame that can bear the weight of the submersible pump. During temporary storage, transportation, installation, etc., the submersible pump can be supported by the filter frame and placed on a flat surface without the need for additional support tools. The filter mesh of the filter is distributed around the circumference and bottom surface of the filter, allowing the medium to enter the pump through the filter mesh holes. At the same time, the filter mesh can prevent large impurities from entering the pump, preventing possible impurities from entering the pump, effectively preventing impurities in the medium from damaging the internal parts of the pump, thereby extending the maintenance cycle of the pump.

[0053] 7. The cryogenic submersible pump for the engine fuel supply system of the LNG ship and floating device provided by the present invention has an anti-loosening structure for the fasteners to prevent them from loosening or falling off during swinging and surge. The connecting fasteners are locked with steel wire locks. The fasteners are locked in pairs instead of in series. When one steel wire lock breaks, the other fasteners can still be reliably prevented from loosening.

[0054] 8. The present invention provides a low-temperature submersible pump for the engine fuel supply system of LNG ships and floating devices. The submersible motor is installed in the motor housing. The pump and the motor are coaxial and immersed in a low-temperature medium as a whole. The medium is insulated and oxygen-free, and the motor does not need to be explosion-proof. The motor is cooled by the low-temperature medium, and no additional heat dissipation is required for the pump motor. The cooling effect is better, saving space and cost.

[0055] 9. The cryogenic submersible pump for the engine fuel supply system of LNG ships and floating devices provided by the present invention reduces the centerline height of the inducer in order to minimize the minimum suction level height of the marine pump. The above technology realizes the ultra-low suction level capability of the liquid cargo pump; the coordination of the inducer, impeller, and final-stage impeller can effectively improve the anti-cavitation performance of the pump.

[0056] Comparison between the present invention and the existing pump structure:

[0057]

[0058]

[0059] In summary, the technical solution of the present invention solves the problems in the prior art such as the poor anti-cavitation ability of the existing LNG pump; the balancing ability cannot meet the ocean swinging conditions, and it is difficult to ensure that the rotor axial force is completely balanced in a wide operating range under the swinging and shaking conditions in the marine environment; the pump bracket adopts a fixed bracket, which is easily damaged under the high stress under the swinging conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0061] Figure 1 It is a schematic diagram of the structure of the present invention;

[0062] Figure 2 This is a schematic structural diagram of the submersible pump of the present invention;

[0063] Figure 3 For the present invention Figure 2 A magnified view of part I;

[0064] Figure 4 This is a schematic diagram of the existing pump structure.

[0065] In the figure: 1, bilge 2, submersible pump 3, pump bracket 4, cryogenic cable 5, cryogenic cable fixing device 6, deck 7, cryogenic cable deck conduit 8, electrical penetration 9, normal temperature cable 10, junction box 11, filter 12, inducer 13, impeller 14, middle section 15, cylinder 16, axial force balancing device 17, outlet section 18, motor housing 19, shaft 20, motor rotor 21, motor stator 22, cryogenic cable junction box 23, motor end cover 24, balancing disk 25, body mouth ring 26, last stage impeller 27, guide vane. DETAILED DESCRIPTION

[0066] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0067] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0068] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0069] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0070] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0071] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0072] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0073] like Figure 1 As shown, the present invention provides a low-temperature submersible pump for an LNG ship and a floating device engine fuel supply system, comprising: a submersible pump 2, a pump bracket 3, a low-temperature cable 4, a low-temperature cable fixing device 5, a low-temperature cable deck conduit 7, an electrical penetration joint 8, a normal temperature cable 9 and a junction box 10; the submersible pump 2 adopts an impeller ring-less structure to prevent the retaining ring from loosening and falling due to mechanical friction during the operation of the pump; the submersible pump 2 is located at the upper part of the bilge 1 and is fixed to the pump tower through the pump bracket 3; an oblong hole is provided at the connection point, and the pump bracket can slide radially under low-temperature conditions, which solves the problem of different shrinkage amounts of the pump casing and the bracket under low-temperature conditions and reduces the stress caused by deformation; the pump bracket is fixed to the pump tower by bolts, and the pump and the pump bracket can be firmly fixed to the pump tower. A low-temperature cable junction box 22 is installed on the upper part of the submersible pump 2, and the motor cable inside the submersible pump 2 and the external low-temperature cable 4 are connected through the low-temperature cable junction box 22; the low-temperature cable 4 is fixed inside the cabin through a low-temperature cable fixing device 5; the low-temperature cable 4 passes through the low-temperature cable deck conduit 7 set on the top deck 6 of the cabin, and is connected to the junction box 10 through the electrical penetration joint 8 and the normal temperature cable 9.

[0074] The submersible pump 2 has a high head and adopts a multi-stage impeller structure, including: an inducer 12, an impeller 13, a middle section 14, a cylinder 15, an axial force balancing device 16, an outlet section 17, a motor housing 18, a shaft 19, a motor rotor 20, a motor stator 21, a motor end cover 23 and a guide vane 27; the motor end cover 23, the motor housing 18, the outlet section 17 and the cylinder 15 are connected in sequence by bolts to form a motor housing; a bearing housing is provided inside the motor end cover 23, and the upper bearing is mounted on the motor end cover; a boss is provided on the lower inner circumference of the motor housing 18, and the motor stator 21 is mounted on the boss; a junction box mounting hole is designed on the side of the motor housing 18 for installing a low-temperature cable junction box 22; the shaft 19 is assembled on the motor end cover 23 and the outlet section 17 through a bearing seat, on which the motor rotor 20 is assembled, and the motor rotor 20 and the motor stator 21 form a submersible motor; the axial force balancing device 16 is mounted on the outlet end 17 and is located inside the outlet section 17 ; A middle section 14 is provided inside the cylinder 15, forming a double-shell barrel bag type pressure-bearing structure, which effectively improves the safety of the pump casing; a plurality of guide vanes 27 and an impeller 13 are installed inside the middle section 14; connecting screws are provided between the middle section 14 and the guide vanes 27, and between the middle section 14 and the middle section 14 to prevent the middle section and the guide vanes from rotating during operation; the impeller 13 is a closed impeller structure, consisting of a front cover, intermediate blades and a rear cover, mounted on the shaft 19, and rotating with the pump shaft. Due to the action of the blades, the medium rotates in the impeller, flows out at a certain speed, and enters the outlet section; the inducer 12 is mounted at the bottom end of the shaft 17, located at the lower part of the lowest impeller 13; the inducer 12 is a cylindrical equal-pitch structure, adopting a larger inlet flow area, a smaller inlet attack angle, and a thinner blade inlet thickness, so that the speed of the medium at the inlet of the inducer 12 is small, the pressure around the blades of the inducer 12 is uniform, and the medium flowing out of the inducer 12 directly enters the impeller 13.

[0075] The low-temperature cable junction box 22 consists of an outer shell and terminal blocks; the connection positions of the terminal blocks and the submersible motor end cables and the low-temperature cables 4 are located inside the low-temperature cable junction box 22. The low-temperature cable junction box 22 protects the cable connection parts to prevent the impact of the medium in the cabin on the joints.

[0076] The motor rotor 20 is supported by two-point bearings, located at the upper and lower ends of the motor respectively. The bearings are deep groove ball bearings, and the bearings are fixed to the shaft by locking nuts; during operation, they are lubricated and cooled by low-temperature medium.

[0077] The outlet section 17 is divided into several independent flow channels; a liquid outlet pipe is provided on the outer circumference of the motor housing 18, and the liquid enters the liquid outlet pipe after being discharged from the outlet section 17; a liquid outlet flow channel is provided inside the motor end cover 23, and the medium enters the outlet pipe through the liquid outlet flow channel; the flow channel, the liquid outlet pipe and the liquid outlet flow channel are connected; the outlet section 17 collects the liquid flowing out of the impeller 13, and transports it to the liquid outlet flow channel through the flow channel and the liquid outlet pipe, converting the velocity energy of the liquid into pressure energy.

[0078] The outlet section 17 is provided with a bearing housing structure, which eliminates the need for a separate bearing housing. Instead, a bearing mounting position is provided in the outlet section 17, where a bearing bushing is installed. The bearing is mounted on the shaft 19 and is mounted in the outlet section 17 via the bearing bushing. The outlet section structure integrates the housing, flow channel, and bearing housing into a compact structure, reduces the height of the pump body, and reduces the equipment weight, meeting the size and weight requirements of equipment used on ships.

[0079] The axial force balancing device 16 includes: a balancing disk 24, a final-stage impeller 26 and a balancing circuit; the balancing disk 24 adopts a conical structure, with the upper section area larger than the lower section area. The balancing disk 24 is located between the impeller rear cover plate and the outlet section 17, and the balancing disk 24 is fixed to the outlet section 17; the final-stage impeller 26 is a closed impeller structure, consisting of a front cover plate, intermediate blades and a rear cover plate, assembled on the shaft 19, and located at the lower part of the balancing disk 14; a gap is left between the final-stage impeller 26 and the body opening ring 25 on the outlet section 17; the outlet of the final-stage impeller 26 is connected to the chamber of the motor housing through a balancing circuit to ensure that the pressure in the motor housing chamber is the same as that of the impeller outlet. The pressure difference at both ends of the balancing disc is small and the sensitivity is high. Under various working conditions, it can quickly balance the axial force so that the bearing is not stressed. Under various working conditions, the balancing disc is not easy to wear during the dynamic balancing process. The axial force balancing structure has low leakage and can effectively improve the efficiency of the pump. The axial force balancing device solves the problem of complete axial force balance under the working conditions of overall shaking and tilting of the pump.

[0080] The shaft 19 is an integral stepped structure; a keyway is machined on the shaft 19, and the inducer 12, impeller 13 and final-stage impeller 26 are all mounted on the shaft by means of keys and keyways; the integral shaft has no connecting shaft structure in the middle and does not require a coupling, resulting in a compact structure, which effectively reduces the height of the pump and improves the reliability of the pump operation. At the same time, it is suitable for installation in compact spaces within ship cabins.

[0081] The filter 11 is installed at the suction port at the bottom of the cylinder 15; the filter 11 is a metal frame structure, the circumference and bottom surface of the filter 11 are welded frames, and the surrounding and bottom frames are covered with a filter screen, which is a perforated plate; the upper flange of the filter 11 is provided with bolt holes, and the upper part of the filter 11 is connected to the cylinder 15 by bolts. The filter frame can bear the weight of the submersible pump. During temporary storage, transportation, installation, etc., the submersible pump can be supported by the filter frame and placed on a flat surface without the need for additional supporting tools. The filter screens of the filter are distributed on the circumference and bottom surface of the filter. The medium can enter the interior of the pump through the filter screen holes. At the same time, the filter screen can prevent large-sized impurities from entering the interior of the pump, which can prevent possible impurities from entering the pump and effectively prevent impurities in the medium from damaging the internal parts of the pump, thereby extending the maintenance cycle of the pump;

[0082] The filter 11 is a half-structure. After the pump is installed, the filter can be removed without disassembling the pump. There is a supporting structure in the filter 11, which can serve as a temporary support during the pump disassembly and assembly process to enable the pump to be placed upright.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cryogenic submersible pump for an LNG ship or floating device engine fuel supply system, characterized in that: The cryogenic submersible pump for the LNG ship and floating device engine fuel supply system comprises: a submersible pump (2), a pump bracket (3), a cryogenic cable (4), a cryogenic cable fixing device (5), a cryogenic cable deck conduit (7), an electrical penetration joint (8), a normal temperature cable (9) and a junction box (10); The submersible pump (2) adopts an impeller without a ring structure to prevent the retaining ring from loosening and falling due to mechanical friction during the operation of the pump; the submersible pump (2) is located at the upper part of the cabin bottom (1) and is fixed to the pump tower through a pump bracket (3); an oblong hole is provided at the connection point, and the pump bracket can slide radially under low temperature conditions, thereby solving the problem of different shrinkage amounts of the pump casing and the bracket under low temperature conditions and reducing the stress caused by deformation; the pump bracket is fixed to the pump tower by bolts, and the pump and the pump bracket can be firmly fixed to the pump tower. A cryogenic cable junction box (22) is installed on the upper part of the submersible pump (2), and the motor cable inside the submersible pump (2) and the external cryogenic cable (4) are connected through the cryogenic cable junction box (22); The cryogenic cable (4) is fixed inside the cabin via a cryogenic cable fixing device (5); After the cryogenic cable (4) passes through a cryogenic cable deck conduit (7) arranged on the cabin top deck (6), it is connected to a junction box (10) via an electrical penetration connector (8) and a normal temperature cable (9).

2. The cryogenic submersible pump for the LNG carrier and floating device engine fuel supply system according to claim 1, characterized in that: The submersible pump (2) has a relatively high head and adopts a multi-stage impeller structure, comprising: an inducer (12), an impeller (13), a middle section (14), a barrel (15), an axial force balancing device (16), an outlet section (17), a motor housing (18), a shaft (19), a motor rotor (20), a motor stator (21), a motor end cover (23) and a guide vane (27); The motor end cover (23), the motor housing (18), the outlet section (17) and the cylinder (15) are connected in sequence by bolts to form a motor housing; A bearing housing is arranged inside the motor end cover (23), and an upper bearing is mounted on the motor housing; A boss is provided on the inner circumference of the lower part of the motor housing (18), and a motor stator (21) is mounted on the boss; The side of the motor housing (18) is designed with a junction box installation hole for installing a low-temperature cable junction box (22); The shaft (19) is assembled on the motor end cover (23) and the outlet section (17) through a bearing seat, and a motor rotor (20) is assembled thereon. The motor rotor (20) and the motor stator (21) form a submersible motor. The axial force balancing device (16) is installed on the outlet end (17) and is located in the outlet section (17); The cylinder (15) is provided with a middle section (14) inside, forming a double-layer shell barrel bag type pressure-bearing structure, which effectively improves the safety of the pump casing; A plurality of guide vanes (27) and an impeller (13) are installed inside the middle section (14); Connecting screws are arranged between the middle section (14) and the guide vanes (27), and between the middle sections (14) and the middle sections (14) to prevent the middle sections and the guide vanes from rotating during operation; The impeller (13) is a closed impeller structure, which is composed of a front cover plate, middle blades and a rear cover plate, and is mounted on a shaft (19) and rotates with the pump shaft. Due to the action of the blades, the medium rotates in the impeller, flows out at a certain speed, and enters the outlet section. The inducer (12) is mounted at the bottom end of the shaft (17) and is located at the bottom of the lowest impeller (13); the inducer (12) is a cylindrical equal pitch structure, and adopts a larger inlet flow area, a smaller inlet angle of attack, and a thinner blade inlet thickness, so that the speed of the medium at the inlet of the inducer (12) is small, the pressure around the blades of the inducer (12) is uniform, and the medium flowing out of the inducer (12) directly enters the impeller (13).

3. The cryogenic submersible pump for the LNG carrier and floating device engine fuel supply system according to claim 1, characterized in that: The low-temperature cable junction box (22) is composed of a housing and wiring terminals; The connection positions of the connection terminals, the submersible motor end cable and the cryogenic cable (4) are located inside the cryogenic cable connection box (22). The cryogenic cable connection box (22) protects the cable connection position to prevent the impact of the medium in the cabin on the joint.

4. The cryogenic submersible pump for the LNG carrier and floating device engine fuel supply system according to claim 2, characterized in that: The motor rotor (20) is supported by two-point bearings, which are respectively located at the upper and lower ends of the motor. The bearings are deep groove ball bearings, and the bearings are fixed to the shaft through locking nuts. During operation, they are lubricated and cooled by low-temperature media.

5. The cryogenic submersible pump for the LNG carrier and floating device engine fuel supply system according to claim 2, characterized in that: The outlet section (17) is divided into several independent flow channels; A liquid outlet pipe is arranged on the outer circumference of the motor housing (18), and the liquid enters the liquid outlet pipe after being discharged from the outlet section (17); The motor end cover (23) is provided with a liquid outlet channel inside, and the medium enters the outlet pipe through the liquid outlet channel; The flow channel, the liquid outlet pipe and the liquid outlet flow channel are connected; The outlet section (17) collects the liquid flowing out of the impeller (13) and transports it to the liquid outlet channel through the flow channel and the liquid outlet pipe, thereby converting the velocity energy of the liquid into pressure energy.

6. The cryogenic submersible pump for the LNG carrier and floating device engine fuel supply system according to claim 2, characterized in that: The outlet section (17) is provided with a bearing box structure, which eliminates the need for an independent bearing box body, and a position for installing a bearing is provided in the outlet section (17). A bearing bushing is installed at the bearing installation position, and the bearing is installed on the shaft (19) and installed in the outlet section (17) through the bearing bushing. The outlet section structure integrates the housing, the flow channel, and the bearing box body into one, has a compact structure, reduces the height of the pump body, and reduces the weight of the equipment, and is suitable for the requirements for equipment size and weight in ships.

7. The cryogenic submersible pump for the LNG carrier and floating device engine fuel supply system according to claim 2, characterized in that: The axial force balancing device (16) comprises: a balancing disc (24), a final-stage impeller (26) and a balancing circuit; The balancing disc (24) adopts a cone-shaped structure, the upper section area is larger than the lower section area, the balancing disc (24) is located between the impeller rear cover plate and the outlet section (17), and the balancing disc (24) is fixed on the outlet section (17); The final impeller (26) is a closed impeller structure, consisting of a front cover plate, intermediate blades and a rear cover plate, mounted on the shaft (19), and located at the lower part of the balance disk (14); a gap is left between the final impeller (26) and the body opening ring (25) on the outlet section (17); The outlet of the last-stage impeller (26) is connected to the chamber of the motor housing through a balancing circuit, ensuring that the pressure of the motor housing chamber is the same as that of the impeller outlet. The pressure difference at both ends of the balancing disc is small, the sensitivity is high, and the axial force can be quickly balanced under various working conditions, so that the bearing is not stressed; under various working conditions, the balancing disc is not easy to wear during the dynamic balancing process of the balancing disc; the axial force balancing structure has a small leakage, which can effectively improve the efficiency of the pump; the axial force balancing device solves the problem of complete axial force balance under the condition of overall shaking and tilting of the pump.

8. The cryogenic submersible pump for the LNG carrier and floating device engine fuel supply system according to claim 2, characterized in that: The shaft (19) is an integrated stepped structure; The shaft (19) is processed with a keyway, and the inducer (12), the impeller (13) and the final impeller (26) are all mounted on the shaft by means of keys and keyways. The shaft of the one-piece structure has no connecting shaft structure in the middle, and no coupling is required. The structure is compact, the height of the pump is effectively reduced, and the reliability of the pump operation is improved. At the same time, the pump is suitable for installation in a compact space in a cabin.

9. The cryogenic submersible pump for the LNG carrier and floating device engine fuel supply system according to claim 1, characterized in that: The filter (11) is installed at the suction port at the bottom of the cylinder (15); The filter (11) is a metal frame structure, the circumference and bottom surface of the filter (11) are welded frames, the surrounding and bottom frames are covered with a filter screen, and the filter screen is a perforated plate; The upper flange of the filter (11) is provided with bolt holes, and the upper part of the filter (11) is connected to the cylinder (15) by bolts. The filter frame can bear the weight of the submersible pump. During temporary storage, transportation, installation, etc., the submersible pump can be supported by the filter frame and placed on a flat surface without the need for additional support tools. The filter screens of the filter are distributed on the circumference and bottom of the filter. The medium can enter the pump through the filter screen holes. At the same time, the filter screen can prevent large-sized impurities from entering the pump, which can prevent possible impurities from entering the pump and effectively prevent impurities in the medium from damaging the internal parts of the pump, thereby extending the maintenance cycle of the pump.

10. The cryogenic submersible pump for the LNG carrier and floating device engine fuel supply system according to claim 9, characterized in that: The filter (11) is a half-structure, and after the pump is installed, the filter can be removed without disassembling the pump; The filter (11) has a supporting structure which can serve as a temporary support during the disassembly and assembly of the pump, allowing the pump to be placed upright.

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