Extractable low-temperature immersed pump for emergency unloading of liquid cargo tank for LNG (Liquefied Natural Gas) ship and floating device

Abstract

The invention discloses an extractable low-temperature immersed pump for emergency unloading of a liquid cargo tank for an LNG (Liquefied Natural Gas) ship and a floating device, and relates to the technical field of immersed pumps, in particular to the extractable low-temperature immersed pump for emergency unloading of the liquid cargo tank for the LNG ship and the floating device. A pump well is arranged at the upper part of a cabin bottom; a lower flange of the pump well is connected with an upper valve body of the bottom valve through a fastener; the immersed pump is mounted on the conical surface of the bottom valve; the upper part of the immersed pump is connected with the bottom end of a low-temperature steel wire rope; a conductor rod is mounted on the immersed pump and connected with a motor cable and a low-temperature cable; the low-temperature cable penetrates through a top plate arranged at the upper end of the pump well and then is connected with the electrical penetrating connector. And the electrical penetration joint is connected with the junction box through a normal-temperature cable on the atmosphere side. According to the technical scheme, the problems that in the prior art, an existing LNG pump is poor in cavitation resistance, and the balance capacity of the LNG pump cannot meet the ocean swing working condition are solved.

Description

Technical Field

[0001] The invention discloses a removable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices, relates to the technical field of submersible pumps, and in particular to a removable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices. Background Art

[0002] At present, cryogenic pumps are required to transport cryogenic media in LNG cryogenic medium transport ships and floating devices. Since the medium has the characteristics of low temperature, flammability, explosion and easy vaporization, the pump equipment for transporting such medium is required to have reliable sealing, small medium vaporization volume and 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, and there are problems such as expensive products and slow service response. The localization of vertical cryogenic marine submersible pump equipment is conducive to cost control in the LNG transportation link, and is conducive to the application expansion of vertical cryogenic marine submersible pumps in the fields of propane, ethylene and other transport ships, and is conducive to the improvement of the design and manufacturing level of large-scale cryogenic submersible pumps in China. Liquid cargo pumps for LNG ships and floating devices are blank in China.

[0003] The existing LNG pumps have poor anti-cavitation capabilities; the existing LNG pumps' balancing capabilities cannot meet the requirements of ocean swaying conditions.

[0004] In view of the problems existing in the above-mentioned prior art, it is very necessary to study and design a new type of extractable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices, so as to overcome the problems existing in the prior art. Summary of the invention

[0005] According to the technical problems that the existing LNG pumps proposed in the prior art have poor anti-cavitation ability and the balancing ability of the LNG pumps cannot meet the ocean swaying conditions, a removable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices is provided. The present invention mainly achieves the ultra-low suction level capability of the liquid cargo pump by designing the impeller and guide shell hydraulics of the high-speed ratio pump and the high cavitation resistance inducer; by setting an axial force balancing device, the balancing device consists of a balancing disc, a balancing drum, an impeller, and a balancing circuit, which solves the problem of complete axial force balance under the overall shaking and tilting conditions of the pump.

[0006] The present invention installs a bottom valve at the bottom of the pump well, and the upper valve body is connected to the pump well flange by fasteners, and can be firmly installed at the bottom of the pump well; when the pump is running, the emergency pump can be installed on the cone surface of the bottom valve, and the bottom valve has the function of supporting the emergency pump; the pump is installed on the bottom valve, and the bottom valve is opened by the gravity of the pump, and the medium enters the pump through the flow channel in the bottom valve. In order to meet the installation size of the pump well, the submersible pump adopts a new compact bottom valve structure with a built-in spring, and the bottom valve spring is arranged inside the lower valve body, which can shorten the axial size of the bottom valve, and is suitable for the requirements of the equipment structure in ships and floating devices.

[0007] The upper part of the submersible pump is connected to the low-temperature steel wire rope, which is fixed in the lifting assembly. During on-site installation, the submersible pump, steel wire rope and other lifting assemblies are installed in advance on the operating platform next to the pump well. The support plate of the first section of steel wire rope is lifted by the crane, and the steel wire rope and the submersible pump are lifted into the pump well. This process is repeated until multiple sections of steel wire rope and the submersible pump are lifted to the bottom of the pump well.

[0008] The original structure requires the installation of a wire rope pole above the pump well, which increases the installation time and there is a risk that fasteners will fall into the pump well. The present invention installs the pump and lifting components such as the wire rope in advance on the operating platform next to the pump well, and uses a quick lifting device to quickly and safely send the submersible pump to the bottom of the pump well.

[0009] The technical means adopted by the present invention are as follows:

[0010] A removable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices comprises: a bottom valve, a submersible pump, a cryogenic cable, a steel wire rope, a pump well, a top plate, an electrical penetration joint, a normal temperature cable and a junction box;

[0011] Further, the pump well is arranged at the upper part of the bilge;

[0012] Further, the lower flange of the pump well is connected to the upper valve body of the bottom valve by fasteners;

[0013] Furthermore, the submersible pump is mounted on the conical surface of the bottom valve, and the bottom valve plays a role in supporting the submersible pump and opening the bottom valve by the gravity of the submersible pump;

[0014] Further, the upper part of the submersible pump is connected to the bottom end of the cryogenic wire rope, and the top end of the wire rope is fixed in the lifting assembly;

[0015] Furthermore, a conductor rod is installed on the upper part of the submersible pump to connect the motor cable and the cryogenic cable;

[0016] Furthermore, the cryogenic cable is connected to the electrical penetration connector after passing through the top plate arranged at the upper end of the pump well;

[0017] Furthermore, the electrical penetration joint is connected to the junction box through a normal temperature cable on the atmosphere side.

[0018] Furthermore, the electrical penetration joint adopts the gas sealing technology of metal and ceramic welding and metal and glass packaging, which prevents the pumped flammable and explosive medium from leaking along the low-temperature cable to the junction box outside the cabin while transmitting electricity, achieving zero leakage of the medium and making the sealing safer and more reliable, thus improving the safety and reliability of the whole machine operation.

[0019] Furthermore, in order to prevent the fasteners from loosening or falling off during swinging or surging, the fasteners of the present invention adopt an anti-loosening structure, the connecting fasteners are locked with steel wire locks, and the fasteners are prevented from loosening in pairs instead of being connected in series as a whole. When a steel wire lock breaks, the other fasteners can still be reliably prevented from loosening.

[0020] Furthermore, the submersible pump needs to be quickly installed in the pump well in an emergency. It is suspended under the top plate by a low-temperature steel wire rope, and the motor cable is connected to the low-temperature cable through a conductor rod. There are many installation steps and the installation time is long. For quick installation, the present invention installs the pump and lifting components such as the steel wire rope on the operating platform next to the pump well in advance during installation, and quickly and safely sends the submersible pump to the bottom of the pump well through a quick lifting device. In order to meet the installation size of the pump well, the submersible pump adopts a new compact bottom valve structure with a built-in spring.

[0021] Furthermore, the submersible pump includes: an inducer, an impeller, a guide vane, an outlet section, an axial force balancing mechanism, a motor housing, a shaft, a motor rotor, a motor stator, a motor end cover and a bearing housing.

[0022] Furthermore, the top and bottom ends of the motor housing are fixedly assembled with a motor end cover and an outlet section by bolts;

[0023] Furthermore, a boss is provided on the inner circumference of the lower part of the motor housing, and the motor stator is installed on the boss;

[0024] Furthermore, a bearing housing is installed between the motor housing and the outlet section;

[0025] Furthermore, a motor rotor is mounted on the shaft and is used in conjunction with the motor stator;

[0026] Furthermore, the upper and lower ends of the shaft are mounted on the motor end cover and the bearing housing respectively;

[0027] Furthermore, the axial force balancing mechanism is assembled on the shaft and fixedly connected to the bearing housing;

[0028] Furthermore, the guide vane, the impeller and the inducer are assembled on the shaft in sequence from top to bottom.

[0029] Furthermore, the inducer 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 inducer inlet is small, the pressure around the inducer blades is uniform, and the medium flowing out of the inducer directly enters the impeller.

[0030] Furthermore, the impeller is a closed impeller structure, which is composed of a front cover plate, middle blades, and a rear cover plate. It 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 guide vane.

[0031] Furthermore, the submersible pump adopts an impeller without a mouth ring structure to prevent the mouth ring from loosening and falling due to mechanical friction during the operation of the pump.

[0032] Furthermore, the liquid enters the pump inlet through the bottom valve, enters the impeller flow channel after passing through the inducer, and then enters the guide vane flow channel. After being discharged from the guide vane, the liquid flows into the pump well through the outlet flow channel of the outlet section and is discharged from the outlet pipe.

[0033] Further, the bearing housing is provided with a bearing housing structure, a bearing bushing is installed at the bearing installation position, the bearing is installed on the shaft, and is installed in the bearing housing through the bearing bushing;

[0034] Furthermore, a groove for assembling the bearing force balancing device is provided at the lower part of the bearing housing.

[0035] Furthermore, the axial force balancing device comprises: a balancing disc, a balancing drum and a balancing circuit;

[0036] Further, the balance drum is mounted on the shaft and is located in a downward groove of the bearing housing;

[0037] Further, the balancing disc is mounted on the shaft and is located below the balancing drum;

[0038] Furthermore, the balancing plate is fixed to the lower part of the bearing housing by screws, and the balancing drum is encapsulated in a groove of the bearing housing.

[0039] Furthermore, the axial force is balanced by a balancing disk and a balancing drum. The balancing mechanism has high sensitivity and can quickly balance the axial force under various working conditions so that the bearing is not subjected to stress. The balancing disk and the balancing drum are not easily worn during the dynamic balancing process of the balancing structure under various working conditions. The axial force balancing structure has a small leakage and can effectively improve the efficiency of the pump. The medium leaks from the rear cavity of the balancing drum and returns to the pump inlet through the return pipe. The axial force balancing device solves the problem of complete balancing of the axial force under the conditions of overall shaking and tilting of the pump.

[0040] Furthermore, the guide vane is divided into several independent flow channels by the blades; the guide vane collects the liquid flowing out of the impeller and transports it to the liquid outlet flow channel in the outlet section, converting the velocity energy of the liquid into pressure energy.

[0041] Furthermore, the shaft is an integrated structure with a keyway machined thereon; the inducer, impeller and balance drum are mounted on the shaft through keys. The shaft of the integrated structure has no connecting shaft structure in the middle, and no coupling is required. 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.

[0042] Furthermore, the shaft is supported by two-point bearings, located at the upper and lower ends of the motor;

[0043] Furthermore, the bearings are deep groove ball bearings, and the bearings are fixed to the shafts by locking nuts. During operation, they are lubricated and cooled by low-temperature media.

[0044] Furthermore, a circular through hole is provided on the upper part of the motor end cover, a conductor rod is installed in the hole, the motor cable is installed at the lower part of the conductor rod, the low-temperature cable is installed at the upper part of the conductor rod, and the motor end cover is connected to the motor cable and the low-temperature cable by installing the conductor rod.

[0045] Compared with the prior art, the present invention has the following advantages:

[0046] 1. The removable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices provided by the present invention adopts the gas sealing technology of metal and ceramic welding and metal and glass packaging for the electrical penetration joint. 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, achieving zero leakage of the medium and making the sealing safer and more reliable. The safety and reliability of the whole machine operation are improved.

[0047] 2. The present invention provides a removable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices. The axial force is balanced by a balancing disk and a balancing drum. The balancing mechanism has high sensitivity and can quickly balance the axial force under various working conditions so that the bearing is not subjected to stress. The balancing disk and the balancing drum are not easily worn during the dynamic balancing process of the balancing structure under various working conditions. The axial force balancing structure has a small leakage and can effectively improve the efficiency of the pump. The medium leaks from the rear cavity of the balancing drum and returns to the pump inlet through the return pipe. The axial force balancing device solves the problem of complete balancing of the axial force under the conditions of overall shaking and tilting of the pump.

[0048] 3. The extractable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices 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 a cabin.

[0049] 4. The extractable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices provided by the present invention reduces the centerline height of the inducer and realizes the ultra-low suction level capability of the liquid cargo pump; through the cooperation of the 11 inducers and the 12 impellers, the anti-cavitation performance of the pump can be effectively improved.

[0050] 5. The present invention provides a removable cryogenic submersible pump for emergency unloading of liquid cargo tanks for 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 cryogenic 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 cryogenic medium and no additional heat dissipation is required for the pump motor, so the cooling effect is better, saving space and cost.

[0051] 6. The extractable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices provided by the present invention has an anti-loosening structure for the fasteners to prevent loosening and falling off during swaying and surge. The connecting fasteners are locked with steel wire locks. The fasteners are prevented from loosening in pairs instead of being connected in series as a whole. When a steel wire lock breaks, the other fasteners can still be reliably prevented from loosening.

[0052] Structural comparison between the present invention and the imported pump:

[0053]

[0054] In summary, the technical solution of the present invention solves the problem in the prior art that the existing LNG pump has poor anti-cavitation ability and the balancing ability of the LNG pump cannot meet the ocean swaying conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative labor.

[0056] Figure 1 It is a schematic diagram of the structure of the present invention;

[0057] Figure 2 It is a schematic diagram of the structure of the submersible pump of the present invention;

[0058] Figure 3 For the present invention Figure 2 Part I enlarged view;

[0059] Figure 4 This is a schematic diagram of the existing structure.

[0060] In the figure: 1, bilge 2, bottom valve 3, submersible pump 4, cryogenic cable 5, wire rope 6, pump well 7, top plate 8, electrical penetration joint 9, normal temperature cable 10, junction box 11, inducer 12, impeller 13, guide vane 14, outlet section 15, axial force balancing mechanism 16, motor housing 17, shaft 18, motor rotor 19, motor stator 20, motor end cover 21, balancing disc 22, balancing drum 23, bearing housing. DETAILED DESCRIPTION

[0061] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments 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.

[0062] 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 by no means 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 creative work are within the scope of protection of the present invention.

[0063] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0064] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps described 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 ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0065] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the 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 contours of each component itself.

[0066] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. 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 figure. For example, if the device in the accompanying 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.

[0067] 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. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0068] like Figure 1As shown, the present invention provides a removable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices, comprising: a bottom valve 2, a submersible pump 3, a cryogenic cable 4, a steel wire rope 5, a pump well 6, a top plate 7, an electrical penetration joint 8, a normal temperature cable 9 and a junction box 10; the pump well 6 is arranged at the upper part of the tank bottom 1; the lower flange of the pump well 6 is connected to the upper valve body of the bottom valve 2 by fasteners; the submersible pump 3 is installed on the conical surface of the bottom valve 2, the bottom valve 2 plays a role in supporting the submersible pump, and opens the bottom valve 2 by the gravity of the submersible pump 3; the upper part of the submersible pump 3 is connected to the bottom end of the cryogenic steel wire rope 5, and the top end of the steel wire rope 5 is fixed in the lifting assembly; a conductor rod is installed on the upper part of the submersible pump 3 to connect the motor cable and the cryogenic cable 4; the cryogenic cable 4 passes through the top plate 7 arranged at the upper end of the pump well 6 and is connected to the electrical penetration joint 8; the electrical penetration joint 8 is connected to the junction box 10 through the normal temperature cable 9 on the atmospheric side. The electrical penetration joint 8 adopts the gas sealing technology of metal and ceramic welding and metal and glass packaging. While transmitting power, it also prevents the pumped flammable and explosive medium from leaking along the low-temperature cable to the junction box 10 outside the cabin, achieving zero leakage of the medium and making the sealing safer and more reliable, thereby improving the safety and reliability of the whole machine operation.

[0069] like Figure 2 As shown, the submersible pump 3 includes: an inducer 11, an impeller 12, a guide vane 13, an outlet section 14, an axial force balancing mechanism 15, a motor housing 16, a shaft 17, a motor rotor 18, a motor stator 19, a motor end cover 20 and a bearing housing 23; the top and bottom ends of the motor housing 16 are fixedly assembled with the motor end cover 20 and the outlet section 14 by bolts; a boss is arranged on the inner circumference of the lower part of the motor housing 16, and the motor stator 19 is mounted on the boss; a bearing housing 23 is assembled between the motor housing 16 and the outlet section 14; a motor rotor 18 used in conjunction with the motor stator 19 is assembled on the shaft 17; the upper and lower ends of the shaft 17 are respectively mounted on the motor end cover 20 and the bearing housing 23; the axial force balancing mechanism 15 is assembled on the shaft 17 and fixedly connected to the bearing housing 23; the guide vane 13, the impeller 12 and the inducer 11 are assembled on the shaft 17 in sequence from top to bottom. The liquid enters the pump inlet through the bottom valve, enters the impeller flow channel after passing through the inducer, and then enters the guide vane flow channel. After being discharged from the guide vane, the liquid flows through the outlet flow channel of the outlet section into the pump well and is discharged from the outlet pipe.

[0070] like Figure 2 As shown, the bearing box 23 is provided with a bearing box structure, a bearing bushing is installed at the bearing installation position, the bearing is installed on the shaft 17, and is installed in the bearing box 23 through the bearing bushing; the lower part of the bearing box 23 is provided with a groove for assembling the bearing force balancing device 15.

[0071] like Figure 3As shown, the axial force balancing device 15 includes: a balancing disc 21, a balancing drum 22 and a balancing circuit; the balancing drum 22 is assembled on the shaft 17 and is located in a downward groove of the bearing housing 23; the balancing disc 21 is assembled on the shaft 17 and is located below the balancing drum 22; the balancing disc 21 is fixed to the lower part of the bearing housing 23 by screws, and the balancing drum 22 is encapsulated in the groove of the bearing housing 23.

[0072] The axial force is balanced by a balancing disc and a balancing drum. The balancing mechanism has high sensitivity and can quickly balance the axial force under various working conditions so that the bearing is not subjected to stress. Under various working conditions, the balancing disc 21 and the balancing drum 22 are not easy to wear during the dynamic balancing process of the balancing structure. The axial force balancing structure has a small leakage and can effectively improve the efficiency of the pump. The medium leaks from the rear cavity of the balancing drum and returns to the pump inlet through the return pipe. The axial force balancing device solves the problem of complete balancing of the axial force under the conditions of overall shaking and tilting of the pump.

[0073] like Figure 2 As shown, the guide vane 13 is divided into several independent flow channels by blades; the guide vane collects the liquid flowing out of the impeller and transports it to the liquid outlet channel in the outlet section, converting the velocity energy of the liquid into pressure energy.

[0074] like Figure 1 As shown, the shaft 17 is an integral structure with a keyway machined thereon; the inducer 11, the impeller 12 and the balance drum 15 are mounted on the shaft 17 by means of a key. The shaft of the integral structure has no connecting shaft structure in the middle, and no coupling is required. 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.

[0075] like Figure 1 As shown, the shaft 17 is supported by two-point bearings, which are 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, it is lubricated and cooled by low-temperature medium.

[0076] like Figure 1 As shown, a circular through hole is provided on the upper part of the motor end cover 20, a conductor rod is installed in the hole, the motor cable is installed at the lower part of the conductor rod, and the low-temperature cable 4 is installed at the upper part of the conductor rod. The motor end cover 20 is connected to the motor cable and the low-temperature cable 4 by installing the conductor rod.

[0077] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned 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 removable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices, characterized in that: The extractable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices comprises: a bottom valve (2), a submersible pump (3), a cryogenic cable (4), a steel wire rope (5), a pump well (6), a top plate (7), an electrical penetration joint (8), a normal temperature cable (9) and a junction box (10); The pump well (6) is arranged at the upper part of the bilge (1); The lower flange of the pump well (6) is connected to the upper valve body of the bottom valve (2) via fasteners; The submersible pump (3) is installed on the conical surface of the bottom valve (2), and the bottom valve (2) plays a role in supporting the submersible pump and opening the bottom valve (2) by the gravity of the submersible pump (3); The upper part of the submersible pump (3) is connected to the bottom end of the cryogenic steel wire rope (5), and the top end of the steel wire rope (5) is fixed in the lifting assembly; A conductor rod is installed on the upper part of the submersible pump (3) to connect the motor cable and the cryogenic cable (4); The cryogenic cable (4) passes through a top plate (7) disposed at the upper end of the pump well (6) and is connected to an electrical penetration connector (8); The electrical penetration joint (8) is connected to the junction box (10) through the normal temperature cable (9) on the atmosphere side. The electrical penetration joint (8) 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 medium from leaking along the low temperature cable to the junction box (10) outside the cabin, so that zero leakage of the medium can be achieved, and the sealing is safer and more reliable. The safety and reliability of the whole machine operation are improved.

2. The extractable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices according to claim 1 is characterized in that: The submersible pump (3) comprises: an inducer (11), an impeller (12), a guide vane (13), an outlet section (14), an axial force balancing mechanism (15), a motor housing (16), a shaft (17), a motor rotor (18), a motor stator (19), a motor end cover (20) and a bearing housing (23). The top and bottom ends of the motor housing (16) are fixedly assembled with a motor end cover (20) and an outlet section (14) by means of bolts; A boss is provided on the inner circumference of the lower part of the motor housing (16), and a motor stator (19) is installed on the boss; A bearing housing (23) is installed between the motor housing (16) and the outlet section (14); The shaft (17) is equipped with a motor rotor (18) for use with a motor stator (19); The upper and lower ends of the shaft (17) are respectively mounted on the motor end cover (20) and the bearing housing (23); The axial force balancing mechanism (15) is assembled on the shaft (17) and fixedly connected to the bearing housing (23); The guide vane (13), impeller (12) and inducer (11) are sequentially assembled on the shaft (17) from top to bottom. The liquid enters the pump inlet through the bottom valve, enters the impeller flow channel after passing through the inducer, and then enters the guide vane flow channel. After being discharged from the guide vane, the liquid flows through the outlet flow channel of the outlet section into the pump well and is discharged from the outlet pipe.

3. The extractable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices according to claim 2 is characterized in that: The bearing housing (23) is provided with a bearing housing structure, a bearing bushing is installed at the bearing installation position, the bearing is installed on the shaft (17), and is installed in the bearing housing (23) through the bearing bushing; The lower part of the bearing housing (23) is provided with a groove for assembling the bearing force balancing device (15).

4. The extractable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices according to claim 2, characterized in that: The axial force balancing device (15) comprises: a balancing disc (21), a balancing drum (22) and a balancing circuit; The balance drum (22) is mounted on the shaft (17) and is located in a downward groove of the bearing housing (23); The balancing disc (21) is mounted on the shaft (17) and is located below the balancing drum (22); The balancing plate (21) is fixed to the lower part of the bearing housing (23) by screws, and the balancing drum (22) is encapsulated in the groove of the bearing housing (23). The axial force is balanced by a balancing disc and a balancing drum. The balancing mechanism has high sensitivity and can quickly balance the axial force under various working conditions so that the bearing is not subjected to stress. Under various working conditions, the balancing disc 21 and the balancing drum 22 are not easy to wear during the dynamic balancing process of the balancing structure. The axial force balancing structure has a small leakage and can effectively improve the efficiency of the pump. The medium leaks from the rear cavity of the balancing drum and returns to the pump inlet through the return pipe. The axial force balancing device solves the problem of complete balancing of the axial force under the conditions of overall shaking and tilting of the pump.

5. The extractable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices according to claim 1, characterized in that: The guide vane (13) is divided into several independent flow channels by blades; the guide vane collects liquid flowing out of the impeller and transports it to the liquid outlet flow channel in the outlet section, converting the velocity energy of the liquid into pressure energy.

6. The extractable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices according to claim 1, characterized in that: The shaft (17) is an integral structure with a keyway machined thereon; the induction wheel (11), the impeller (12) and the balance drum (15) are mounted on the shaft (17) by means of a key. The shaft of the integral structure has no connecting shaft structure in the middle and does not require a coupling. The structure is compact, the height of the pump is effectively reduced, the reliability of the pump operation is improved, and the pump is suitable for installation in a compact space in a cabin.

7. The extractable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices according to claim 2, characterized in that: The shaft (17) 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, which are fixed to the shafts by locking nuts and lubricated and cooled by low-temperature media during operation.

8. The extractable cryogenic submersible pump for emergency unloading of liquid cargo tanks for LNG ships and floating devices according to claim 2, characterized in that: A circular through hole is arranged on the upper part of the motor end cover (20), a conductor rod is installed in the hole, the motor cable is installed at the lower part of the conductor rod, and the cryogenic cable (4) is installed at the upper part of the conductor rod. The motor end cover (20) is connected to the motor cable and the cryogenic cable (4) by installing the conductor rod.

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