High temperature medium long shaft transfer pump

Abstract

The application provides a high-temperature medium long-axis conveying pump and belongs to the technical field of conveying pumps. The pump body comprises a volute and a cover body connected with each other, an impeller is arranged in the volute, a driving mechanism for driving the impeller to rotate is arranged, an inducer is arranged at the front end of the impeller in the volute; the inducer comprises a hub connected with the driving mechanism, helical blades are arranged on the outer side of the hub in the circumferential direction, splitter blades are arranged on the outer side of the hub in the gap between the helical blades, and a cylinder is arranged on the outer side of the hub in the volute. The helical blades of the inducer are designed as a variable-pitch structure, the inlet section is designed as an equal-pitch structure to smoothly guide the liquid to flow in, the pitch of the outlet section gradually increases, the cross-sectional area of the flow channel can be gradually expanded, the flow rate of the liquid is gradually reduced, the pressure is gradually increased, the whole process is smoothly pressurized, the local vaporization caused by the sudden change of the pressure is effectively reduced, and the generation of bubbles is inhibited.

Description

Technical Field

[0001] This invention relates to the field of pump technology, and in particular to a long-shaft pump for high-temperature media. Background Technology

[0002] The high-temperature medium long-shaft transfer pump is a vertically installed centrifugal pump with its motor located above the liquid surface. The long shaft drives the impeller, which is immersed in the high-temperature liquid, to rotate and draw out the liquid. Because the high-temperature medium is easy to vaporize, when the pressure of the liquid at the pump inlet is lower than the corresponding saturated vapor pressure at that temperature, the liquid will vaporize, thereby generating a large number of bubbles at the impeller inlet. These bubbles will flow into the high-pressure zone of the impeller with the liquid and burst instantly, generating a strong impact force that will damage the impeller and the inner wall of the volute. In addition, the impact generated by the bursting of bubbles will also cause pump vibration and noise.

[0003] To suppress cavitation, existing technologies typically add an inducer before the impeller to improve the pump's anti-cavitation performance by pre-pressurizing the inlet liquid. However, most existing inducers adopt a constant pitch design, where the pitch of the blades along the axial direction remains unchanged. The medium velocity and pressure cannot change gradually during the flow process. After the liquid enters the inducer from the inlet, the pressure change is concentrated in the area near the blade inlet. The pressure rise process is not smooth enough, and the liquid is prone to vaporization due to local pressure changes, which limits the bubble suppression effect. In addition, there is a blade tip clearance between the inducer and the pump inlet housing. The fluid in this clearance will backflow under the pressure difference between the pressure surface and the suction surface of the blade, and the energy carried by this part of the fluid cannot be effectively utilized, which will cause energy loss and reduce the head of the inducer, thereby weakening the pre-pressurization effect. Therefore, this application provides a high-temperature medium long shaft transfer pump to meet the requirements. Summary of the Invention

[0004] The purpose of this invention is to provide a high-temperature medium long-shaft conveying pump to solve the above-mentioned problems. By setting the spiral blades to a variable pitch structure with a constant pitch at the inlet and a gradually increasing pitch at the outlet, the liquid can achieve stable pressurization when flowing through the inducer, effectively avoiding local vaporization caused by sudden pressure changes, thereby solving the problems of uneven liquid pressure changes and limited bubble suppression effect mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A high-temperature medium long-shaft conveying pump includes a pump body, the pump body including a volute and a cover connected to each other, an impeller is disposed inside the volute, and a drive mechanism for driving the impeller to rotate is provided, and an inducer is disposed inside the volute and at the front end of the impeller. The inducer wheel includes a hub connected to the drive mechanism. A helical blade is arranged circumferentially on the outer side of the hub. A flow divider blade is arranged on the outer side of the hub and within the gap of the helical blade. A cylinder is installed inside the volute and on the outer side of the hub. A helical guide groove is formed on the inner wall of the cylinder, and the helical direction of the helical guide groove is opposite to the helical direction of the helical blade, which is used to enhance the backflow of the blade tip gap and suppress cavitation.

[0006] Optionally, the drive mechanism includes a drive motor and a drive shaft. The end of the drive shaft away from the drive motor extends into the volute and connects to the impeller. A protective tube is provided on the outside of the drive shaft and between the drive motor and the cover to provide protection for the drive shaft.

[0007] Optionally, the drive shaft is formed by connecting multiple shaft segments sequentially via couplings, and the protective tube is formed by connecting multiple tube segments sequentially via flanges. The splicing length of the protective tube corresponds to the splicing length of the drive shaft, and is used to adjust the length of the drive shaft and the protective tube according to different underwater depths.

[0008] Optionally, the spiral blades are designed with a variable pitch, with a constant pitch structure in the inlet section and a gradually increasing pitch in the outlet section along the flow direction. The blades at the junction of the constant pitch section and the variable pitch section are tangentially transitioned to ensure that the liquid medium is smoothly pressurized when it flows through the inducer.

[0009] Optionally, the diverting blade is disposed at the variable pitch section. The diverting blade includes a first diverting blade and a second diverting blade. Two second diverting blades are disposed on the outer side of each first diverting blade, and the blade length of the first diverting blade is greater than that of the second diverting blade, which is used to cut and divert the medium flowing through the variable pitch section.

[0010] Optionally, a guide portion is provided on the side of the hub away from the helical blades. The guide portion has a conical structure, and the conical direction of the guide portion is opposite to the conical direction of the hub. It is used to guide the flow of the medium to avoid generating eddies when the medium passes over the hub.

[0011] Optionally, the volute has an inner recess that mates with the guide portion, and a liquid flow gap is formed between the guide portion and the inner recess. The cross-section of the liquid flow gap gradually decreases along the direction of medium flow, which is used to guide the liquid medium to smoothly transition to the impeller.

[0012] Optionally, the inner wall of the volute is provided with a insertion groove, the cylinder is installed inside the insertion groove, and a sealing gasket is provided between the cylinder and the groove wall to prevent liquid medium from leaking from between the cylinder and the groove wall.

[0013] Optionally, a sealing mechanism is provided outside the drive shaft and inside the cover. The sealing mechanism includes a stop ring fixed outside the drive shaft, a pressure ring slidably connected outside the drive shaft and below the stop ring, an elastic element sleeved outside the drive shaft and between the stop ring and the pressure ring, a moving ring provided below the pressure ring, a stationary ring sleeved inside the cover and outside the drive shaft, and a friction ring that fits between the stationary ring and the moving ring, for dynamically sealing the inside of the pump body when the drive shaft rotates.

[0014] Optionally, a drain pipe is fixedly connected to one side of the volute, and multiple support members are provided on the outside of the drain pipe. The support members are connected to the protective pipe to provide auxiliary support for the drain pipe.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: In the above-mentioned scheme, the high-temperature medium long shaft transfer pump provided in this application designs the helical blades of the inducer as a variable pitch structure. The inlet section is guided to flow in smoothly with a constant pitch structure, and the pitch of the outlet section gradually increases. This can make the cross-sectional area of ​​the flow channel gradually expand, thereby gradually reducing the liquid flow rate and gradually increasing the pressure, achieving stable pressurization throughout the process. This effectively reduces local vaporization caused by sudden pressure changes and thus inhibits the generation of bubbles. Furthermore, by setting the first and second splitting blades at the variable pitch section, the liquid in the flow channel can be cut and split, thereby making the flow field distribution of the medium more uniform, reducing the local low pressure area, and further preventing the generation of bubbles. The spiral guide grooves on the inner wall of the cylinder, which are opposite to the spiral blades, can guide and pressurize the backflow medium in the blade tip gap and then re-enter the mainstream medium. This reduces the energy loss caused by the backflow in the blade tip gap due to the pressure difference between the pressure surface and the suction surface, thereby inhibiting cavitation. By setting a reverse guide on the back side of the hub, and combining it with the concave part inside the volute to form a liquid flow gap with a gradually decreasing cross-section, the liquid can smoothly accelerate and transition to the impeller when flowing through the gap, avoiding eddies and flow turbulence caused by abrupt changes in cross-section. This can reduce the amount of medium flow loss and thus improve the pump's operating efficiency. Attached Figure Description

[0016] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate embodiments of the invention and, together with the specification, further serve to explain the principles of the invention and enable those skilled in the art to practice and use the invention.

[0017] Figure 1 This is a schematic diagram of the overall structure of the high-temperature medium long-shaft delivery pump of the present invention; Figure 2 For the present invention Figure 1A partial sectional view of the diagram; Figure 3 This is a cross-sectional view of the volute, impeller, inducer, and cylinder of the present invention; Figure 4 For the present invention Figure 3 A partial schematic diagram; Figure 5 This is a schematic diagram showing the connection between the drive shaft, sealing mechanism, inducer wheel, and cylinder of the present invention; Figure 6 This is a three-dimensional structural diagram of the inducer wheel of the present invention; Figure 7 This is a frontal view of the inducer wheel of the present invention; Figure 8 This is a three-dimensional structural diagram of the cylindrical body of the present invention.

[0018] Figure label: 1. Pump body; 11. Volute; 111. Recess; 12. Cover; 13. Impeller; 2. Drain pipe; 21. Support component; 3. Drive mechanism; 31. Drive motor; 32. Drive shaft; 33. Protective pipe; 4. Sealing mechanism; 41. Stop ring; 42. Pressure ring; 43. Elastic component; 44. Moving ring; 45. Stationary ring; 46. Friction ring; 5. Inducer wheel; 51. Hub; 511. Spiral blade; 512. First diverter blade; 513. Second diverter blade; 52. Guide section; 6. Cylinder; 61. Spiral guide groove.

[0019] As shown in the figure, specific structures and devices are marked in the figure to clearly illustrate the structure of the embodiments of the present invention. However, this is only for illustrative purposes and is not intended to limit the present invention to this specific structure, device and environment. Those skilled in the art can adjust or modify these devices and environments according to specific needs. Detailed Implementation

[0020] The high-temperature medium long-shaft conveying pump provided by the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should also be noted that, to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art can use other alternative methods to implement some known technologies; moreover, the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0021] It should be noted that the use of terms such as "an embodiment," "an embodiment," "an exemplary embodiment," and "some embodiments" in the specification indicates that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments (whether explicitly described or not) should be within the knowledge of those skilled in the art.

[0022] Generally, terms can be understood at least partly from their use in context. For example, depending at least partly on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in a singular sense, or a combination of features, structures, or characteristics in a plural sense. Additionally, the term "based on" can be understood not necessarily to convey an exclusive set of factors, but rather, alternatively, depending at least partly on the context, to allow for the presence of other factors that are not necessarily explicitly described.

[0023] It is understood that the meanings of “on”, “above”, and “above” in this invention should be interpreted in the broadest manner, such that “on” means not only “directly on” something, but also includes the meaning of being “on” something with an intervening feature or layer, and that “above” or “above” means not only “on” something, but also includes the meaning of being “on” something without an intervening feature or layer.

[0024] Furthermore, spatially related terms such as “below,” “under,” “lower,” “above,” and “upper” are used herein for convenience to describe the relationship of one element or feature to one or more other elements or features, as illustrated in the accompanying drawings. Spatially related terms are intended to cover different orientations in the use or operation of the device other than those depicted in the accompanying drawings. The device may be oriented in other ways, and the spatially related descriptive terms used herein can be interpreted similarly.

[0025] like Figures 1 to 3As shown, an embodiment of the present invention provides a high-temperature medium long-shaft transfer pump, including a pump body 1. The pump body 1 includes a volute 11 and a cover 12 connected together. An impeller 13 is disposed inside the volute 11, and a drive mechanism 3 for driving the impeller 13 to rotate. The drive mechanism 3 includes a drive motor 31 and a drive shaft 32. One end of the drive shaft 32 away from the drive motor 31 extends into the volute 11 and connects to the impeller 13. A protective tube 33 is disposed on the outside of the drive shaft 32 and between the drive motor 31 and the cover 12 to provide protection for the drive shaft 32. Since high-temperature medium long-shaft transfer pumps are usually used in deep underwater conditions, the drive shaft 32 needs to extend a long distance to transmit power from the drive motor 31 to the impeller 13. The exposed drive shaft 32 at high speeds... When rotating, the drive shaft 32 is easily damaged by external impurities or external impacts. The protective tube 33 can protect the drive shaft 32, avoid interference and damage from the external environment, and ensure the stability and safety of the transmission. A drain pipe 2 is fixedly connected to one side of the volute 11. Multiple support members 21 are provided on the outside of the drain pipe 2. The support members 21 are connected to the protective tube 33. The support member 21 consists of a connecting arm and clamps at both ends. The two clamps are respectively installed on the drive shaft 32 and the drain pipe 2 to provide auxiliary support for the drain pipe 2. The support member 21 connects the drain pipe 2 and the protective tube 33 into one unit, which can provide auxiliary support for the drain pipe 2, prevent the drain pipe 2 from vibrating or deforming under the impact of high pressure liquid, and ensure the sealing reliability of the connection between the drain pipe 2 and the volute 11. Furthermore, such as Figure 2 As shown, the drive shaft 32 is composed of multiple shaft segments connected sequentially by couplings, and the protective pipe 33 is composed of multiple pipe segments connected sequentially by flanges. The splicing length of the protective pipe 33 corresponds to the splicing length of the drive shaft 32, and is used to adjust the length of the drive shaft 32 and the protective pipe 33 according to different submerged depths. Since the submerged depth requirements of the pump are different under different installation conditions, if the drive shaft 32 and the protective pipe 33 adopt an integrated structure, then the entire drive shaft 32 and the protective pipe 33 need to be customized separately for each submerged depth. By setting the drive shaft 32 and the protective pipe 33 to a segmented splicing structure, the number of shaft segments and pipe segments can be flexibly selected and combined according to the actual submerged depth, which reduces manufacturing and inventory costs and improves the versatility and on-site adaptability of the equipment.

[0026] like Figure 4 and Figure 6As shown, an inducer 5 is provided inside the volute 11 and at the front end of the impeller 13. The inducer 5 includes a hub 51 connected to the drive shaft 32. A spiral blade 511 is provided circumferentially on the outer side of the hub 51. A flow divider blade is provided on the outer side of the hub 51 and in the gap between the spiral blades 511. Since the high-temperature medium contains a high saturated vapor at high temperature, the liquid is prone to vaporization at the inlet of the impeller 13 to generate bubbles. After the bubbles enter the high-pressure zone of the impeller 13, they will be destroyed and generate impact force, which will cause cavitation of the impeller 13, resulting in a decrease in the pump's flow rate, head and efficiency. By providing an inducer 5 at the front end of the impeller 13, the liquid entering the volute 11 can be pre-pressurized by the spiral blades 511, so that the liquid pressure increases before entering the impeller 13, thereby preventing the liquid from vaporizing at the inlet of the impeller 13 due to the pressure being lower than the saturated vapor pressure, and thus suppressing the generation of bubbles. It is worth mentioning that, such as Figure 6 and Figure 7 As shown, the spiral blade 511 features a variable pitch design. The inlet section has a constant pitch structure (as shown in F1), while the outlet section's pitch gradually increases along the flow direction (as shown in F2). The constant pitch structure in the inlet section allows the liquid to be smoothly guided into the inlet, avoiding impact losses and local low-pressure areas caused by abrupt changes in the flow channel. The gradually increasing pitch in the outlet section leads to a gradual expansion of the flow channel cross-sectional area, resulting in a gradual decrease in liquid velocity and a gradual increase in pressure. This achieves stable pressurization, ensuring that the liquid pressure remains higher than the saturated vapor pressure at that temperature, thereby effectively suppressing bubble formation. Furthermore, the blades are tangent at the junction of the constant pitch and variable pitch sections. The transition section is used to smoothly pressurize the liquid medium as it flows through the inducer 5. The flow divider blades are set at the variable pitch section, and the blades are tangentially transitioned at the junction of the constant pitch section and the variable pitch section. This can eliminate the abrupt change in the flow channel cross-section and avoid the generation of vortices due to the rapid change in the flow channel shape. The flow divider blades include a first flow divider blade 512 and a second flow divider blade 513. Two second flow divider blades 513 are set on the outer side of each first flow divider blade 512, and the blade length of the first flow divider blade 512 is greater than that of the second flow divider blade 513. This is used to cut and divide the medium flowing through the variable pitch section, which can more precisely improve the uniformity of the flow field.

[0027] like Figure 4 and Figure 8As shown, a cylindrical body 6 is installed inside the volute 11 and outside the hub 51. A groove is provided on the inner wall of the volute 11, and the cylindrical body 6 is installed inside the groove. A sealing gasket is provided between the cylindrical body 6 and the groove wall to prevent leakage of liquid medium from between the cylindrical body 6 and the groove wall. A circumferentially oriented spiral guide groove 61 is formed on the inner wall of the cylindrical body 6, and the spiral direction of the spiral guide groove 61 is opposite to the spiral direction of the spiral blade 511. This enhances the backflow of the blade tip clearance to suppress cavitation. During the liquid flow through the inducer 5, the spiral direction of the spiral blade 511... The transfer causes the liquid to tend to diverge radially, and some of the liquid will diffuse to the outer periphery and fail to participate in the pressurization process effectively. The cylinder 6 can constrain the liquid around the inducer 5 in the annular flow channel, so that the liquid always flows axially. At the same time, due to the pressure difference between the pressure surface and the suction surface of the blade, some fluid will flow back from the high-pressure side to the low-pressure side through the blade tip gap, forming a blade tip gap backflow. The reverse spiral guide groove 61 can enhance this backflow and make the backflowing fluid re-enter the mainstream, so that the head of the inducer 5 remains unchanged or increases slightly, further improving the anti-cavitation performance.

[0028] like Figure 4 and Figure 6 As shown, a guide portion 52 is provided on the side of the hub 51 away from the helical blade 511. The guide portion 52 has a conical structure, and the conical direction of the guide portion 52 is opposite to the conical direction of the hub 51. It is used to guide the flow of the medium to avoid the generation of eddies when the medium passes over the hub 51. The volute 11 has an inner recess 111 that cooperates with the guide portion 52. A liquid flow gap is formed between the guide portion 52 and the inner recess 111. The cross-section of the liquid flow gap gradually decreases along the medium flow direction to guide the liquid medium to smoothly transition to the impeller 13. The hub 51 has a conical structure with a small front end and a large rear end. The liquid flows along the conical surface. When the liquid flows backward to the back side of the hub 51, the cross-section of the flow channel suddenly expands, which easily forms vortices in the back side region. Vortices consume energy, reduce flow efficiency, and may cause vibration. A guide part 52 with a conical direction opposite to the back side of the hub 51 is provided to guide and constrain the flow path of the liquid and eliminate vortices caused by abrupt changes in cross-section. The cross-section of the liquid flow gap formed between the guide part 52 and the concave part 111 gradually decreases along the flow direction, which allows the liquid to accelerate smoothly in the gap and transition to the impeller 13 in a better flow state, avoiding energy loss due to flow turbulence before the liquid enters the impeller 13.

[0029] like Figure 3 and Figure 5As shown, a sealing mechanism 4 is provided outside the drive shaft 32 and inside the cover 12. The sealing mechanism 4 includes a stop ring 41 fixed to the outside of the drive shaft 32, a pressure ring 42 slidably connected to the outside of the drive shaft 32 and below the stop ring 41, an elastic element 43 sleeved between the stop ring 41 and the pressure ring 42, a moving ring 44 provided below the pressure ring 42, and a stationary ring 45 sleeved inside the cover 12 and outside the drive shaft 32. A friction ring 46 is provided between the stationary ring 45 and the moving ring 44 for dynamic sealing of the inside of the pump body 1 when the drive shaft 32 rotates. When the drive shaft 32 is rotating, the moving ring... 44 rotates synchronously with the drive shaft 32. The stationary ring 45 is fixed inside the cover 12 and remains stationary. The friction ring 46 between the two forms a sealing surface during relative rotation. The elastic element 43 continuously applies a thrust to the pressure ring 42. The pressure ring 42 transmits the thrust to the moving ring 44, so that the moving ring 44 always has a tendency to move towards the stationary ring 45. This ensures that the friction ring 46 is always tightly fitted during long-term operation. Even if the friction ring 46 experiences slight wear, the elastic force of the elastic element 43 can automatically compensate for the wear and maintain the sealing pressure. This ensures that the medium inside the pump body 1 will not leak outward along the drive shaft 32 under dynamic conditions of high-speed rotation of the drive shaft 32.

[0030] Working principle of the invention: The drive motor 31 is started to drive the drive shaft 32, impeller 13 and inducer 5 to rotate synchronously. At this time, the liquid medium enters from the inlet of the volute 11 and first flows through the inducer 5. As the spiral blades 511 rotate with the hub 51 to do work on the liquid, the medium is pre-pressurized. The spiral blades 511 adopt a variable pitch design. The liquid is smoothly guided into the inlet in the constant pitch section. After entering the variable pitch section, as the pitch gradually increases, the cross-sectional area of ​​the flow channel gradually expands, the liquid flow velocity gradually decreases and the pressure gradually increases, achieving stable pressurization. This allows the liquid to obtain a larger pressure before entering the impeller 13, thereby suppressing the generation of bubbles. Furthermore, at the variable pitch section, the first splitter blade 512 and the second splitter blade 513 rotate synchronously with the hub 51, which can cut and split the liquid in the variable pitch section, improve the uniformity of the medium flow field, reduce the local low pressure area, and further suppress the generation of bubbles. During the process of liquid flowing through the inducer wheel 5, the cylinder 6 confines the liquid around the inducer wheel 5 within the annular flow channel. Due to the pressure difference between the pressure surface and suction surface of the blades, some fluid will flow back from the high-pressure side to the low-pressure side when passing through the blade tip gap. The reverse spiral guide groove 61 can return this part of the fluid to the main body, so that the head of the inducer wheel 5 remains unchanged or increases slightly, thereby improving the anti-cavitation performance. When the liquid flows through the spiral blade 511 and flows towards the back side of the hub 51, it will enter the liquid flow gap of the concave part 111. The conical guide part 52 can eliminate the eddies caused by the sudden change in cross section, while the gradually narrowing liquid flow gap can make the liquid smoothly accelerate to the impeller 13. The high-pressure liquid, after being pre-pressurized by the inducer 5, enters the volute 11 and gains centrifugal potential energy under the high-speed rotation of the impeller 13. As the pressure continues to rise, it is eventually discharged from the drain port of the volute 11 through the drain pipe 2. While the drive shaft 32 rotates, the sealing mechanism 4 dynamically seals the inside of the pump body 1. Specifically, the elastic element 43 pushes the pressure ring 42 to slide along the drive shaft 32, and the pressure ring 42 pushes the moving ring 44 to move towards the stationary ring 45, so that the friction ring 46 between the moving ring 44 and the stationary ring 45 remains in contact, thereby preventing the medium from leaking outward along the drive shaft 32. When the pump needs to be applied to different submerged depths, the number of shaft segments of the drive shaft 32 can be increased or decreased by the coupling, and the number of pipe segments of the protective pipe 33 can be increased or decreased accordingly by the flange to adapt to different installation conditions.

[0031] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the following preferred embodiments; however, those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-temperature medium long-shaft conveying pump, comprising a pump body (1), the pump body (1) comprising a volute (11) and a cover (12) connected together, an impeller (13) disposed within the volute (11), and a drive mechanism (3) for driving the impeller (13) to rotate, characterized in that, An inducer wheel (5) is provided inside the volute (11) and at the front end of the impeller (13). The inducer wheel (5) includes a hub (51) connected to the drive mechanism (3). A helical blade (511) is arranged circumferentially on the outer side of the hub (51). A flow divider blade is arranged on the outer side of the hub (51) and in the gap of the helical blade (511). A cylinder (6) is installed inside the volute (11) and on the outer side of the hub (51). A helical guide groove (61) is provided on the inner wall of the cylinder (6) and is arranged circumferentially. The helical direction of the helical guide groove (61) is opposite to the helical direction of the helical blade (511) to enhance the backflow of the blade tip gap and suppress cavitation. The hub (51) is provided with a guide (52) on the side away from the helical blade (511). The guide (52) has a conical structure and the conical direction of the guide (52) is opposite to that of the hub (51). It is used to guide the flow of the medium to avoid the generation of eddies when the medium passes over the hub (51).

2. The high-temperature medium long-shaft conveying pump according to claim 1, characterized in that, The drive mechanism (3) includes a drive motor (31) and a drive shaft (32). The end of the drive shaft (32) away from the drive motor (31) extends into the volute (11) and is connected to the impeller (13). A protective tube (33) is provided on the outside of the drive shaft (32) and between the drive motor (31) and the cover (12) to provide protection for the drive shaft (32).

3. The high-temperature medium long-shaft conveying pump according to claim 2, characterized in that, The drive shaft (32) is formed by connecting multiple shaft segments in sequence through a coupling, and the protective tube (33) is formed by connecting multiple tube segments in sequence through a flange. The splicing length of the protective tube (33) corresponds to the splicing length of the drive shaft (32) and is used to adjust the length of the drive shaft (32) and the protective tube (33) according to different underwater depths.

4. The high-temperature medium long-shaft conveying pump according to claim 1, characterized in that, The spiral blade (511) is designed with a variable pitch. The inlet section has a constant pitch structure, and the pitch of the outlet section gradually increases along the flow direction. The blades at the junction of the constant pitch section and the variable pitch section are tangentially transitioned to ensure that the liquid medium is smoothly pressurized when it flows through the inducer (5).

5. The high-temperature medium long-shaft conveying pump according to claim 4, characterized in that, The diversion blades are located at the variable pitch section. The diversion blades include a first diversion blade (512) and a second diversion blade (513). Two second diversion blades (513) are provided on the outer side of each first diversion blade (512). The blade length of the first diversion blade (512) is greater than that of the second diversion blade (513), which is used to cut and divert the medium flowing through the variable pitch section.

6. The high-temperature medium long-shaft conveying pump according to claim 1, characterized in that, The volute (11) has an inner recess (111) that cooperates with the guide (52). A liquid flow gap is formed between the guide (52) and the inner recess (111). The cross-section of the liquid flow gap gradually decreases along the direction of medium flow, which is used to guide the liquid medium to smoothly transition to the impeller (13).

7. The high-temperature medium long-shaft conveying pump according to claim 1, characterized in that, The inner wall of the volute (11) is provided with a plug groove, the cylinder (6) is installed inside the plug groove, and a sealing gasket is provided between the cylinder (6) and the groove wall of the plug groove to prevent liquid medium from leaking from the cylinder (6) and the groove wall of the plug groove.

8. The high-temperature medium long-shaft conveying pump according to claim 2, characterized in that, A sealing mechanism (4) is provided outside the drive shaft (32) and inside the cover (12). The sealing mechanism (4) includes a stop ring (41) fixed outside the drive shaft (32), a pressure ring (42) slidably connected outside the drive shaft (32) and below the stop ring (41), an elastic element (43) sleeved between the stop ring (41) and the pressure ring (42) outside the drive shaft (32), a moving ring (44) is provided below the pressure ring (42), a stationary ring (45) is sleeved inside the cover (12) and outside the drive shaft (32), and a friction ring (46) is provided between the stationary ring (45) and the moving ring (44) for dynamic sealing of the pump body (1) when the drive shaft (32) rotates.

9. The high-temperature medium long-shaft conveying pump according to claim 1, characterized in that, A drain pipe (2) is fixedly connected to one side of the volute (11). Multiple support members (21) are provided on the outside of the drain pipe (2). The support members (21) are connected to the protective pipe (33) to provide auxiliary support for the drain pipe (2).

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