Vertical pipeline shield pump

Abstract

A vertical pipeline shield pump comprises a vertically-installed pump body, the pump body is connected to a vertical pipeline in series through a suction cover and an outlet cover, a motor stator, a motor rotor and a pump impeller are arranged in the pump body, the motor stator isolates a stator winding and a conveying medium through a stator shielding sleeve, and the motor rotor and the pump impeller are coaxially connected through a pump shaft. The pump is provided with a main circulation loop and an auxiliary circulation loop, a medium in the main circulation loop enters through a suction cover, enters a motor outer shell to absorb heat after being pressurized by a pump impeller and guided by a guide vane in sequence, and then is conveyed to a rear pipeline through an outlet cover; in the auxiliary circulation loop, a pump impeller outlet diversion medium enters a pump rear rotor cavity through a front bearing body circulation hole, circulates along the inner wall of a stator shielding sleeve after being pressurized by an auxiliary impeller and is converged into main circulation. The motor outer shell is of a three-layer structure, the middle layer and the outermost layer are connected through a rib plate, a pump shaft penetrates through a rear bearing body and other components to achieve stable supporting, meanwhile, a power sealing assembly and a safety backflow valve are arranged, and efficient, stable and leakage-free operation of the pump is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of pumps, and particularly relates to a vertical pipeline canned pump. BACKGROUND

[0002] As a general mechanical equipment for conveying liquid, the core function of a pipeline pump is to convert mechanical energy into kinetic energy and pressure energy of liquid by driving an impeller to rotate through power (such as a motor, a diesel engine, etc.), so as to realize continuous conveying, pressurizing or circulating of liquid. The pipeline pump has the remarkable feature of compact structure, and can be directly installed in a pipeline, thereby saving a large amount of space.

[0003] Among the types of pipeline pumps, a pipeline canned pump is a special pump with the characteristics of no leakage and high reliability. It adopts a canned motor design, cancels the traditional mechanical seal, and realizes isolation through a shielding sleeve between the stator and the rotor, so that the pumped medium is completely enclosed in the system, effectively avoiding the leakage risk caused by mechanical seal wear. Therefore, the pipeline canned pump is widely used in fields with strict sealing requirements such as chemical industry, pharmaceutical industry, nuclear power, etc., and is particularly suitable for conveying toxic, flammable and explosive, strongly corrosive or high-purity media (such as liquid chlorine, liquefied gas, strong acid and strong base).

[0004] However, the existing pipeline canned pump is mostly of horizontal structure, which limits its installation scene and can only be installed in a horizontal pipeline close to the ground, and cannot be applied to the installation demand of vertical or high-altitude pipelines. At the same time, during the operation of the traditional pipeline canned pump, the internal circulating medium is difficult to effectively take away the heat generated by the motor, and a cooling jacket needs to be provided on the motor shell for cooling, which not only requires more pipelines to be configured on site, but also needs to prepare sufficient cooling water source, and the cooling water pipeline needs to be regularly descaled, resulting in relatively complicated maintenance work and relatively high maintenance cost of the equipment.

[0005] In addition, the traditional pipeline canned pump also has deficiencies in flow control. Due to the limitation of its structural design, when installed in a high-altitude vertical pipeline, it is difficult to set up a bypass pipeline to adjust the flow, and it is difficult to ensure that the pump outlet flow is always greater than the minimum flow requirement. Once the flow is too small, it will cause poor heat dissipation of the pump, resulting in an increase in the temperature of the canned motor or the bearing, which may trigger an over-temperature protection shutdown, and in severe cases, the winding may even be burned out; at the same time, the high operating temperature of the pump may also cause local vaporization of the medium (especially for volatile liquids), forming bubbles and aggravating equipment damage. SUMMARY

[0006] Therefore, the present application provides a vertical pipeline canned pump to solve the problems of limited installation scene, complex cooling system and difficult flow control, so as to improve the applicability, stability and operating efficiency of the equipment, and reduce the maintenance cost and operation difficulty.

[0007] In order to achieve the above object, the present application provides the following technical scheme: A vertical pipeline canned pump, comprising a pump body in a vertical installation structure, the pump body is installed in series on a vertical pipeline through a suction cover and an outlet cover;

[0008] The pump body is provided with a motor stator, a motor rotor and a pump impeller; the motor stator is isolated from the conveying medium by a stator shielding sleeve, and the motor rotor is coaxially connected with the pump impeller through a pump shaft;

[0009] Further comprising a main circulation loop and an auxiliary circulation loop:

[0010] The main circulation loop path is: the medium enters the pump body through the suction cover, is pressurized by the pump impeller in turn and enters the motor outer shell body after being guided by the guide vane, absorbs the heat of the motor stator and is transported to the rear pipeline by the outlet cover;

[0011] The auxiliary circulation loop path is: the split medium at the pump impeller outlet enters the pump rotor cavity through the front bearing body circulation hole, is pressurized by the auxiliary impeller and circulates along the inner wall of the stator shielding sleeve to the outlet cover, and finally merges into the pump outlet main circulation.

[0012] As a preferred scheme of the vertical pipeline canned pump, the motor outer shell body is a three-layer structure, the innermost layer of the motor outer shell body is the stator shielding sleeve, the intermediate layer and the outermost layer of the motor outer shell body are rigidly connected through circumferentially distributed rib plates, and the intermediate layer and the outermost layer of the motor outer shell body bear the outlet pressure.

[0013] As a preferred scheme of the vertical pipeline canned pump, in the auxiliary circulation loop, a power sealing assembly is arranged below the auxiliary impeller, the power sealing assembly comprises a rotating ring and a stationary ring, the upper side of the rotating ring is a high-pressure area, and the lower side of the rotating ring is a low-pressure area;

[0014] The rotating ring is automatically adjusted by the pressure difference and closely adheres to the stationary ring during work; the rotating ring is fixed in the circumferential direction with the pump shaft through a key groove and rotates synchronously with the pump shaft, and the medium leaked from the end face of the rotating ring enters an annular collection groove and is forced to be recirculated to the rotor cavity in the high-pressure area under the action of the rotating centrifugal force of the rotating ring.

[0015] As a preferred scheme of the vertical pipeline canned pump, the material of the rotating ring is selected from graphite or silicon carbide; the rotating ring is provided with a sealing groove, a collection groove and a friction end face, the sizes of the sealing groove and the collection groove are determined according to the sealing pressure and satisfy the formula:

[0016]

[0017] In the formula, p is the sealing pressure, F is the thrust of the medium on the rotating ring, and A is the effective force area of the rotating ring;

[0018] The static ring surface is sprayed or hardfaced with hard alloy, and the coating thickness satisfies the formula: delta=k*v, wherein delta is the coating thickness, k is a coefficient related to the material, and v is the pump axial speed.

[0019] As the preferred solution of the vertical pipeline canned pump, a safety backflow valve is arranged at the outlet of the pump body, and the safety backflow valve is of a spring type structure.

[0020] When the product of the pressure acting on the sealing surface and the area of the sealing surface is greater than the pressure of the spring of the safety backflow valve, the spring is compressed, the sealing surface is opened, and the medium is discharged through the backflow hole.

[0021] The sealing surface of the valve body of the safety backflow valve is a conical surface, and the sealing surface of the valve disc is a spherical surface, and the sealing is realized through line contact, and the sealing surface on the valve disc and the guide rail are nitrided or sprayed with hard alloy.

[0022] The adjusting screw of the safety backflow valve is welded and fixed and sealed after the factory test, and the pre-tightening force of the adjusting screw satisfies the formula: F pre =k s *x, wherein F pre is the pre-tightening force, k s is the spring stiffness, and x is the spring pre-compression amount.

[0023] As the preferred solution of the vertical pipeline canned pump, the pump shaft passes through the rear bearing body, the angular contact ball bearing and the bearing pressure cover, the angular contact ball bearing is axially positioned in the rear bearing body through the bearing pressure cover, the rear bearing body is rigidly connected with the outlet cover, and the end of the pump shaft extends to the inside of the outlet cover.

[0024] As the preferred solution of the vertical pipeline canned pump, the pump body further comprises a middle shell, a sliding shaft bushing, a sliding bearing sleeve, an elastic sleeve, a shaft sleeve, a rear bearing body and a junction box assembly.

[0025] The middle shell is bolt-connected with the suction cover and the front bearing body through flanges; the sliding shaft bushing is installed in the inner hole of the sliding bearing sleeve in interference fit; and the elastic sleeve is nested on the outside of the shaft sleeve and elastically abuts against the rear bearing body.

[0026] The junction box assembly is sealingly connected with the motor outer shell through flange faces.

[0027] As the preferred solution of the vertical pipeline canned pump, the number n and the arrangement of the rib plates are determined according to the size of the motor outer shell and the flow requirement of the medium, and satisfy the fluid mechanics model: delta P=f(n,v',d)

[0028] delta P=f(n,v',d)

[0029] Wherein, ΔP is the flow passage pressure loss, v' is the medium flow rate, and d is the flow passage equivalent diameter, so as to optimize the irregular vortex or turbulence at the pump impeller outlet due to turning and space size change.

[0030] As the preferred solution of the vertical pipeline canned pump, the sealing gap δ between the dynamic ring and the static ring of the power sealing assembly seal According to the working pressure p of the pump op , the rotating speed n rot Parameter design, meet the leakage model:

[0031]

[0032] Wherein, Q is the leakage, k' is the coefficient related to the medium, m is the gap index, and Δp is the pressure difference on both sides of the dynamic ring and the static ring.

[0033] As the preferred solution of the vertical pipeline canned pump, the spring selection of the safety backflow valve is determined according to the rated working pressure p of the pump rat , the spring stiffness k s satisfies:

[0034]

[0035] Wherein, A seal is the effective area of the sealing surface, and x op is the additional compression amount of the spring under the working pressure.

[0036] The present application has the following advantages:

[0037] First, the vertical installation structure is adopted, and the suction cover and the outlet cover can be directly connected in series on the vertical pipeline or the high-altitude pipeline, compared with the traditional horizontal pipeline pump, no additional ground space is occupied, the installation space is significantly saved, and the application scenarios are widened.

[0038] Second, the canned motor and the pump are integrated, there is no mechanical seal, the motor rotor and the pump impeller are coaxially connected through the pump shaft, the stator winding and the conveying medium are isolated by combining the stator shielding sleeve, the leakage risk caused by mechanical seal wear is eliminated from the structure, and the conveying scene of the medium with high sealing requirement such as toxic, flammable and explosive, and strong corrosion is especially suitable.

[0039] Third, in the main circulating loop, the conveying medium directly absorbs the heat generated by the motor stator when flowing through the motor outer shell, without the need to equip the cooling jacket and the external cooling water pipeline required by the traditional canned pump, the on-site pipeline configuration is reduced, the regular descaling maintenance work of the cooling water pipeline is avoided, the equipment maintenance cost and the operation difficulty are reduced.

[0040] Fourth, the auxiliary circulation loop adopts high-pressure circulation design, the high-pressure medium branched at the outlet of the impeller is pressurized by the auxiliary impeller and then flows through the motor cavity and bearing part, can efficiently take away the heat generated by the motor rotor and bearing, and the high-pressure environment can prevent the medium from vaporizing due to temperature rise, and ensure that the pump can stably operate under the working condition of high-temperature and high-pressure medium conveying. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only exemplary, and for those skilled in the art, other drawings can be derived from the provided drawings without creative labor.

[0042] The structures, proportions, sizes, etc. shown in the specification are only used to cooperate with the content disclosed in the specification, to be understood and read by those skilled in the art, and are not used to limit the limiting conditions that the present application can be implemented, so they do not have technical significance. Any modification of structure, change of proportion relationship or adjustment of size, without affecting the effect and purpose that the present application can produce, should still fall within the scope of the technical content disclosed by the present application.

[0043] Figure 1 A vertical pipeline canned motor pump cross-sectional view provided in the embodiment of the present application;

[0044] Figure 2 A main circulation loop schematic diagram of the vertical pipeline canned motor pump provided in the embodiment of the present application;

[0045] Figure 3 A motor outer shell schematic diagram of the vertical pipeline canned motor pump provided in the embodiment of the present application;

[0046] Figure 4 An auxiliary circulation loop schematic diagram of the vertical pipeline canned motor pump provided in the embodiment of the present application;

[0047] Figure 5 A power seal assembly cross-sectional view of the vertical pipeline canned motor pump provided in the embodiment of the present application;

[0048] Figure 6 A power seal assembly sealing principle schematic diagram of the vertical pipeline canned motor pump provided in the embodiment of the present application;

[0049] Figure 7 A power seal assembly dynamic ring schematic diagram of the vertical pipeline canned motor pump provided in the embodiment of the present application

[0050] Figure 8 A power seal assembly static ring schematic diagram of the vertical pipeline canned motor pump provided in the embodiment of the present application;

[0051] Figure 9 Figure 1 is a schematic diagram of a vertical pipeline canned pump safety backflow valve provided in an embodiment of the present application.

[0052] In the figure, 1, suction cover; 2, pump impeller; 3, guide vane; 4, middle section shell; 5, power seal assembly; 6, front bearing body; 7, sliding shaft bushing; 8, sliding bearing sleeve; 9, elastic sleeve; 10, shaft sleeve; 11, auxiliary impeller; 12, motor stator; 13, motor outer shell; 14, motor rotor; 15, pump shaft; 16, rear bearing body; 17, angular contact ball bearing; 18, bearing gland; 19, outlet cover; 20, junction box assembly; 21, safety backflow valve; 22, stator shielding sleeve; 23, rib plate; 24, dynamic ring; 25, static ring; 26, sealing groove; 27, collection groove; 28, friction end face. DETAILED DESCRIPTION

[0053] The embodiments of the present application will be described in detail with specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure. Obviously, the described embodiments are part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0054] Reference Figure 1 , Figure 2 , Figure 3 and Figure 4 , the embodiment of the present application provides a vertical pipeline canned pump, comprising a pump body in a vertical installation structure, the pump body is installed in series through the suction cover 1 and the outlet cover 19 on the vertical pipeline; the vertical installation structure breaks through the limitation that the traditional horizontal pipeline pump can only be installed on the horizontal pipeline, and can adapt to the installation scene of high altitude or vertical pipeline through the series connection of the suction cover 1 and the outlet cover 19 with the vertical pipeline, thereby saving space.

[0055] Among them, the motor stator 12, the motor rotor 14 and the pump impeller 2 are arranged in the pump body; the motor stator 12 is isolated from the conveying medium by the stator shielding sleeve 22, the motor rotor 14 and the pump impeller 2 are coaxially connected through the pump shaft 15; the isolation of the motor stator 12 from the conveying medium is realized by the stator shielding sleeve 22, which can prevent the medium from contacting the stator winding and causing motor failure, and ensure the safe operation of the motor. The coaxial connection of the motor rotor 14 and the pump impeller 2 means that the two have the same speed, which can reduce the loss in the energy transmission process and improve the efficiency.

[0056] The main circulation loop path is: the medium enters the pump body through the suction cover 1, is pressurized by the pump impeller 2 in sequence and is guided by the guide vane 3, enters the motor outer shell 13, absorbs the heat of the motor stator 12, and is transported to the subsequent pipeline by the outlet cover 19; the auxiliary circulation loop path is: the medium at the outlet of the pump impeller 2 enters the pump rear rotor cavity through the circulation hole of the front bearing body 6, is pressurized by the auxiliary impeller 11, and circulates along the inner wall of the stator shield sleeve 22 to the outlet cover 19, and finally merges into the pump outlet main circulation.

[0057] Specifically, in the main circulation loop, the medium enters the pump body, obtains kinetic energy and pressure energy through impeller rotation, and the guide vane 3 converts the kinetic energy of the medium discharged by the impeller into pressure energy and guides the medium to flow to the motor outer shell 13. When the medium flows through the motor outer shell 13, the heat generated by the operation of the motor stator 12 is absorbed by using the heat transfer principle to cool the motor, and finally transported to the subsequent pipeline without additional cooling device. The auxiliary circulation loop is to divert part of the medium from the outlet of the impeller, and these media enter the rear rotor cavity and are pressurized again by the auxiliary impeller 11, so that the high pressure state of the rear rotor cavity can be maintained to prevent the medium from vaporizing due to temperature rise. At the same time, the medium flowing along the inner wall of the stator shield sleeve 22 can carry away the heat of the motor rotor 14, and also play a lubricating role for related parts, and finally merge into the main circulation to ensure the stable operation of the pump.

[0058] Referring to Figure 2 In the embodiment, the motor outer shell 13 has a three-layer structure, the innermost layer of the motor outer shell 13 is the stator shield sleeve 22, the middle layer and the outermost layer of the motor outer shell 13 are rigidly connected through circumferentially distributed rib plates 23, and the middle layer and the outermost layer of the motor outer shell 13 bear the outlet pressure.

[0059] Specifically, the three-layer structure of the motor outer shell 13 has clear division of labor, the innermost layer of the stator shield sleeve 22 is the key to isolate the stator winding from the medium to prevent the medium from invading the motor. The middle layer and the outermost layer bear the outlet pressure, which can ensure the structural stability of the outer shell in the high-pressure medium environment. The circumferentially distributed rib plates 23 rigidly connect the middle layer and the outermost layer, which not only enhances the overall strength of the outer shell to resist the stress generated by the medium pressure and thermal expansion and contraction, but also plays a guiding role for the flowing medium, optimizes the flow state of the medium, reduces vortex and turbulence, and improves the efficiency of the pump.

[0060] Referring to Figure 1 In the embodiment, the pump shaft 15 passes through the rear bearing body 16, the angular contact ball bearing 17 and the bearing pressure cover 18, the angular contact ball bearing 17 is axially positioned in the rear bearing body 16 through the bearing pressure cover 18, the rear bearing body 16 is rigidly connected with the outlet cover 19, and the end of the pump shaft 15 extends to the inside of the outlet cover 19.

[0061] Specifically, the pump shaft 15 is a core component connecting the motor rotor 14 and the pump impeller 2, which passes through multiple components and extends to the inside of the outlet cover 19, and needs to maintain a stable operating state. The angular contact ball bearing 17 can bear axial force and radial force, and is axially positioned in the rear bearing body 16 through the bearing pressure cover 18, which can limit the axial displacement of the bearing and ensure the stability of the bearing position. The rear bearing body 16 is rigidly connected with the outlet cover 19, which provides stable support for the entire shafting and ensures that the pump shaft 15 does not vibrate or deviate excessively during high-speed rotation, thereby ensuring the smooth operation of the pump.

[0062] Referring to Figure 1 In this embodiment, the pump body further comprises a middle shell 4, a sliding shaft bushing 7, a sliding bearing sleeve 8, an elastic sleeve 9, a shaft sleeve 10, a rear bearing body 16 and a junction box assembly 20; the middle shell 4 is bolted to the suction cover 1 and the front bearing body 6 through flanges; the sliding shaft bushing 7 is installed in the inner hole of the sliding bearing sleeve 8 in interference fit; the elastic sleeve 9 is nested on the outside of the shaft sleeve 10 and elastically abuts against the rear bearing body 16; and the junction box assembly 20 is sealingly connected to the motor outer shell 13 through a flange face.

[0063] Specifically, the middle shell 4 is bolted to the suction cover 1 and the front bearing body 6 through flanges, which is a firm and reliable connection mode that can ensure the stability of the relative positions of the parts of the pump body and bear the force generated by the medium pressure. The sliding shaft bushing 7 is installed in the inner hole of the sliding bearing sleeve 8 in interference fit, which can ensure that there is no relative sliding between the two, and the sliding shaft bushing 7 can reduce the friction when the pump shaft 15 rotates and protect the pump shaft 15 and the bearing sleeve. The elastic sleeve 9 is nested on the outside of the shaft sleeve 10 and elastically abuts against the rear bearing body 16, and the elastic property can absorb the vibration and impact generated during pump operation, reduce the rigid collision between the parts, and prolong the service life. The junction box assembly 20 is sealingly connected to the motor outer shell 13, which can prevent external dust, moisture and other substances from entering the motor interior, ensure the stability of the electrical performance of the motor, and also prevent internal medium leakage.

[0064] Referring to Figure 5 , Figure 6 , Figure 7 and Figure 8 In this embodiment, in the auxiliary circulation loop, a dynamic sealing assembly 5 is arranged below the auxiliary impeller 11, the dynamic sealing assembly 5 comprises a dynamic ring 24 and a static ring 25, the upper side of the dynamic ring 24 is a high-pressure area, and the lower side of the dynamic ring 24 is a low-pressure area.

[0065] When working, the dynamic ring 24 is automatically adjusted by pressure difference and closely adheres to the static ring 25; the dynamic ring 24 is fixed in the circumferential direction with the pump shaft 15 through a key groove and rotates synchronously with the pump shaft 15, and the medium leaked from the end face of the dynamic ring 24 enters the annular collection groove 27 and is forced to be recirculated to the rotor cavity of the high pressure area under the centrifugal force generated by the rotation of the dynamic ring 24.

[0066] Specifically, in the power sealing assembly 5, the upper side of the dynamic ring 24 is the high pressure area, and the lower side is the low pressure area. The pressure difference will push the dynamic ring 24 to approach and closely adhere to the static ring 25, forming a sealing surface to prevent large leakage of the medium. The dynamic ring 24 is fixed in the circumferential direction with the pump shaft 15 through a key groove, ensuring that the dynamic ring 24 rotates synchronously with the pump shaft 15, and there is no relative rotation between the two, reducing wear. When a small amount of medium leaks from the end face into the annular collection groove 27, the centrifugal force generated by the rotation of the dynamic ring 24 will throw these media to the outside of the collection groove 27, so that they are forced to be sent back to the rotor cavity of the high pressure area, realizing the recovery of the leaked medium and enhancing the sealing effect.

[0067] In a possible embodiment, the material of the dynamic ring 24 is selected from graphite or silicon carbide; the dynamic ring 24 is provided with a sealing groove 26, a collection groove 27 and a friction end face 28, and the sizes of the sealing groove 26 and the collection groove 27 are determined according to the sealing pressure and satisfy the formula:

[0068]

[0069] In the formula, p is the sealing pressure, F is the thrust of the medium on the dynamic ring 24, and A is the effective force area of the dynamic ring 24;

[0070] The surface of the static ring 25 is sprayed or hardfaced with hard alloy, and the coating thickness satisfies δ=k·v, wherein δ is the coating thickness, k is a coefficient related to the material, and v is the linear speed of the pump shaft 15.

[0071] Specifically, graphite and silicon carbide have good self-lubricating property and wear resistance, and are suitable as the material of the dynamic ring 24, which can reduce the friction loss when the dynamic ring 24 is closely adhered and rotated with the static ring 25.

[0072] The sizes of the sealing groove 26 and the collection groove 27 are calculated according to the sealing pressure, which can be determined according to the thrust of the medium on the dynamic ring 24 and the effective force area of the dynamic ring 24 to determine the sealing pressure and design appropriate groove sizes to ensure the sealing and collection effect. The surface of the static ring 25 is sprayed or hardfaced with hard alloy, which can improve the surface hardness and wear resistance and prolong the service life. The coating thickness is related to the linear speed of the pump shaft 15. In the formula δ=k·v, the greater the linear speed of the pump shaft 15, the more serious the wear of the surface of the static ring 25, so the coating thickness needs to be increased accordingly. The coefficient k is determined according to the material properties of the hard alloy used.

[0073] The friction end face 28 mainly functions to form a sealing interface by close adhesion of the dynamic ring 24 and the static ring 25, so as to prevent the conveying medium from leaking from the high-pressure area to the low-pressure area in large quantity. During operation, the dynamic ring 24 is automatically adhered to the friction end face of the static ring 25 due to the pressure difference between the upper side and the lower side, and the dynamic ring 24 rotates synchronously with the pump shaft 15, so that a very thin medium film is formed between the friction end faces 28, which not only plays a sealing role, but also reduces the abrasion caused by direct contact of the two, thereby ensuring the reliability and durability of the sealing.

[0074] Referring to Figure 9 In a possible embodiment, a safety backflow valve 21 is arranged at the outlet of the pump body, and the safety backflow valve 21 is of a spring type structure.

[0075] When the product of the pressure acting on the sealing surface and the area of the sealing surface is greater than the pressure of the spring of the safety backflow valve 21, the spring is compressed, the sealing surface is opened, and the medium is discharged through the backflow hole.

[0076] The sealing surface of the valve body of the safety backflow valve 21 is a conical surface, and the sealing surface of the valve disc is a spherical surface, and the sealing is realized through line contact. The sealing surface on the valve disc and the guide rail are nitrided or sprayed with hard alloy.

[0077] The adjusting screw of the safety backflow valve 21 is welded and fixed and sealed after factory test, and the pre-tightening force of the adjusting screw satisfies F pre =k s ·x, wherein F pre is the pre-tightening force, k s is the spring stiffness, and x is the spring pre-compression amount.

[0078] Specifically, the working of the spring type safety backflow valve 21 is based on the force balance principle. In normal operation, the spring pressure makes the sealing surface adhere, thereby preventing the backflow of the medium. When the pump outlet flow is too small, the medium pressure rises, the thrust acting on the sealing surface exceeds the spring pressure, the spring is compressed, the sealing surface is opened, the medium backflows through the backflow hole, and the phenomenon of “pump suffocation” caused by too small flow of the pump is avoided. The sealing surface of the valve body is a conical surface, the sealing surface of the valve disc is a spherical surface, and the line contact sealing can ensure good adhesion at different angles and improve the sealing reliability. The sealing surface on the valve disc and the guide rail are nitrided or sprayed with hard alloy, which can enhance the wear resistance and ensure effective sealing after long-term use.

[0079] The pre-tightening force of the adjusting screw is determined through the formula F pre =k s ·x, the spring pre-compression amount x is adjusted during the factory test, the appropriate pre-tightening force can be set, and the safety backflow valve 21 is ensured to be opened at the preset pressure. The welding and fixing of the adjusting screw can prevent the loosening of the adjusting screw during use, and ensure the stable operation of the backflow valve.

[0080] In one possible embodiment, the number n and arrangement of the ribs 23 are determined according to the size of the motor housing 13 and the medium flow requirement, satisfying the fluid mechanics model:

[0081] ΔP = f(n, v', d)

[0082] wherein ΔP is the flow passage pressure loss, v' is the medium flow rate, and d is the flow passage equivalent diameter, to optimize the irregular vortex or turbulence at the pump impeller 2 outlet due to the change in direction and space size.

[0083] Specifically, the number and arrangement of the ribs 23 affect the flow state of the medium in the flow passage of the motor housing 13. The fluid mechanics model shows that the flow passage pressure loss is related to the number of ribs 23, the medium flow rate, and the flow passage equivalent diameter. By reasonably designing the ribs 23, the medium flow can be guided, the vortex and turbulence at the impeller outlet due to the change in direction and space size can be reduced, the medium flow can be made more stable, the pressure loss can be reduced, and the efficiency of the pump can be improved. Meanwhile, the ribs 23 can also enhance the structural strength of the motor housing 13.

[0084] In one possible embodiment, the sealing gap δ between the dynamic ring 24 and the static ring 25 of the dynamic sealing assembly 5 seal is determined according to the working pressure p of the pump op and the rotational speed n rot of the pump, satisfying the leakage model:

[0085]

[0086] wherein Q is the leakage, k' is a coefficient related to the medium, m is the gap index, and Δp is the pressure difference between the two sides of the dynamic ring 24 and the static ring 25.

[0087] Specifically, the sealing gap between the dynamic ring 24 and the static ring 25 is a key factor affecting the leakage. The higher the working pressure and the greater the rotational speed, the more stringent the requirement for the sealing gap. The leakage model shows that the leakage is proportional to the m-th power of the sealing gap and the square root of the pressure difference between the two sides of the dynamic ring 24 and the static ring 25. By designing a suitable sealing gap δ seal , the leakage can be controlled within the allowable range, and the sealing effect of the dynamic sealing assembly 5 can be ensured, wherein the coefficient k' and the gap index m are related to the viscosity and other characteristics of the medium.

[0088] In one possible embodiment, the spring type of the safety backflow valve 21 is determined according to the rated working pressure P of the pump rat , and the spring stiffness k s satisfies:

[0089]

[0090] In the formula, A seal is the effective area of the sealing surface, x op is the additional compression of the spring under working pressure.

[0091] Specifically, the spring stiffness of the safety backflow valve 21 is a key parameter that needs to be matched with the rated working pressure of the pump.p rat ·A seal is the thrust of the medium on the sealing surface under the rated working pressure, minus the pre-tightening force F pre , and then divided by the additional compression x of the spring under working pressure op . The obtained spring stiffness can ensure that the spring provides sufficient force to close the sealing surface during normal operation, and when the pressure exceeds the rated value, the spring is compressed, the sealing surface is opened to achieve backflow, and the safe operation of the pump is ensured.

[0092] The working principle of the present application is based on the vertical installation structure, the integrated design of the shielded motor and the pump, and the synergistic effect of the double circulation loop. The specific process is as follows:

[0093] When the pump is started, the medium enters the pump body through the suction cover 1. In the main circulation loop, the medium first flows through the pump impeller 2, which rotates at high speed under the drive of the motor rotor 14, and the medium is pressurized by the centrifugal force to obtain kinetic energy and pressure energy. Subsequently, the medium pressurized by the pump impeller 2 enters the guide vane 3, which converts the kinetic energy of the medium into pressure energy through its internal flow channel and guides the medium to flow smoothly into the motor outer shell 13. Since the motor stator 12 generates heat during operation, the medium flowing through the motor outer shell 13 absorbs this heat through heat conduction, thereby cooling the motor stator 12, and finally is transported to the outlet cover 19 and enters the rear pipeline.

[0094] In the auxiliary circulation loop, a portion of the medium is diverted from the outlet of the pump impeller 2, and these media enter the pump rear rotor cavity through the circulation holes on the front bearing body 6. The medium entering the pump rear rotor cavity is pressurized again by the auxiliary impeller 11, and after obtaining sufficient pressure, it flows along the inner wall of the stator shield sleeve 22 towards the outlet cover 19, and finally merges into the main circulation loop, together with the medium of the main circulation, and is transported to the rear pipeline. This auxiliary circulation not only carries away the heat generated by the operation of the motor rotor 14, but also maintains the high pressure state of the pump rear rotor cavity to prevent the medium from vaporizing due to temperature rise.

[0095] The motor stator 12 is isolated from the conveying medium by the stator shield sleeve 22, avoiding direct contact between the conveying medium and the stator winding, preventing corrosion or damage to the stator winding, and ensuring the safe operation of the motor. The motor rotor 14 and the pump impeller 2 are coaxially connected through the pump shaft 15, which enables the rotation of the motor rotor 14 to directly drive the pump impeller 2 to rotate synchronously, reducing the loss in the energy transmission process and improving the working efficiency of the pump.

[0096] The motor outer shell 13 adopts a three-layer structure, the innermost layer is a stator shield sleeve 22, the middle layer and the outermost layer are rigidly connected through circumferentially distributed ribs 23. This structure design enables the middle layer and the outermost layer to jointly bear the pressure at the outlet, and the ribs 23 can also guide the flowing medium, optimize the flow state of the medium, reduce the vortex and turbulence generated in the flow process of the medium, and improve the operating efficiency of the pump.

[0097] The pump shaft 15 passes through the rear bearing body 16, the angular contact ball bearing 17 and the bearing pressure cover 18 during operation, the angular contact ball bearing 17 is axially positioned in the rear bearing body 16 through the bearing pressure cover 18, and the rear bearing body 16 is rigidly connected with the outlet cover 19. This structure provides stable support for the pump shaft 15, ensuring that the pump shaft 15 can rotate smoothly.

[0098] The power sealing assembly 5 is arranged on the lower side of the auxiliary impeller 11, the upper side of the dynamic ring 24 is a high-pressure area, and the lower side is a low-pressure area. Under the action of the pressure difference, the dynamic ring 24 will automatically adjust and tightly fit with the static ring 25 to form a sealing surface, preventing a large amount of leakage of the medium. At the same time, the dynamic ring 24 is fixed in the circumferential direction with the pump shaft 15 through a key groove and rotates synchronously with the pump shaft 15. When a small amount of medium leaks from the end face and enters the annular collection groove 27, the leaked medium will be forced back to the rotor cavity of the high-pressure area under the action of the centrifugal force generated by the rotation of the dynamic ring 24, further enhancing the sealing effect.

[0099] When the pressure at the pump outlet abnormally rises, the product of the pressure acting on the sealing surface of the safety backflow valve 21 and the area of the sealing surface will increase. When the thrust is greater than the pressure of the spring, the spring is compressed, the sealing surface is opened, and the medium is discharged through the backflow hole, thereby reducing the pressure at the pump outlet and avoiding damage to the pump due to excessive pressure. The valve body sealing surface of the safety backflow valve 21 is a conical surface, and the valve core sealing surface is a spherical surface. The sealing is achieved through line contact, ensuring the reliability of the sealing.

[0100] In addition, the number and arrangement of the ribs 23 on the motor outer shell 13 are determined according to the size of the motor outer shell 13 and the flow requirements of the medium, meet a specific fluid mechanics model, and can further optimize the flow state of the medium at the outlet of the pump impeller 2, reduce the generation of irregular vortex or turbulence, and improve the working efficiency of the pump. The sealing gap between the dynamic ring 24 and the static ring 25 of the power sealing assembly 5 is designed according to the working pressure, rotating speed and other parameters of the pump, meets a leakage model, and ensures effective sealing under different working conditions. The spring of the safety backflow valve 21 is selected according to the rated working pressure of the pump, and the spring stiffness meets a specific formula, ensuring that the sealing surface can be reliably sealed under normal working pressure and can be opened in time when the pressure is too high.

[0101] Through the cooperation of the above parts, the vertical pipeline canned motor pump can realize stable, efficient and leakage-free operation on the vertical pipeline.

[0102] Although the present application has been described in detail with general description and specific embodiments above, some modifications or improvements can be made on the basis of the present application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present application, all belong to the scope of the present application claimed.

Claims

1. A vertical pipeline canned motor pump, characterized in that: The pump body comprises a vertical installation structure, wherein the pump body is installed in series on a vertical pipeline through a suction cover (01) and an outlet cover (19); The pump body is provided with a motor stator (12), a motor rotor (14) and a pump impeller (02); the motor stator (12) is isolated from the conveying medium by a stator shielding sleeve (22); the motor rotor (14) and the pump impeller (02) are coaxially connected via a pump shaft (15); It also includes the main circulation loop and auxiliary circulation loop: The main circulation path is as follows: the medium enters the pump body through the suction cover (01), is pressurized by the pump impeller (02), and is guided by the guide vane (03) before entering the motor outer shell (13), absorbs the heat of the motor stator (12), and is then transported to the rear pipeline through the outlet cover (19); The auxiliary circulation loop path is as follows: the diverted medium at the outlet of the pump impeller (02) enters the pump rear rotor cavity through the circulation hole of the front bearing body (06), is pressurized by the auxiliary impeller (11), circulates along the inner wall of the stator shielding sleeve (22) to the outlet cover (19), and finally merges into the main circulation at the pump outlet.

2. The vertical pipeline canned motor pump according to claim 1, characterized in that: The motor housing (13) is a three-layer structure, the innermost layer of the motor housing (13) is the stator shielding sleeve (22), the middle layer and the outermost layer of the motor housing (13) are rigidly connected by circumferentially evenly distributed ribs (23), and the middle layer and the outermost layer of the motor housing (13) bear outlet pressure.

3. The vertical pipeline canned motor pump according to claim 1, characterized in that: In the auxiliary circulation loop, a dynamic sealing assembly (05) is provided on the lower side of the auxiliary impeller (11), and the dynamic sealing assembly (05) includes a dynamic ring (24) and a static ring (25), the upper side of the dynamic ring (24) is a high-pressure area, and the lower side of the dynamic ring (24) is a low-pressure area; During operation, the dynamic ring (24) is automatically adjusted by the pressure difference and fits tightly with the static ring (25); the dynamic ring (24) is circumferentially fixed to the pump shaft (15) through a keyway and rotates synchronously with the pump shaft (15); after the medium leaked from the end face of the dynamic ring (24) enters the annular collecting groove (27), it is forced to recirculate to the rotor cavity in the high-pressure area under the action of the centrifugal force of the rotation of the dynamic ring (24).

4. The vertical pipeline canned motor pump according to claim 3, characterized in that: The material of the dynamic ring (24) is graphite or silicon carbide; the dynamic ring (24) is provided with a sealing groove (26), a collecting groove (27) and a friction end surface (28); the sizes of the sealing groove (26) and the collecting groove (27) are determined by calculation based on the sealing pressure, and satisfy the formula: Wherein, p is the sealing pressure, F is the thrust of the medium on the dynamic ring (24), and A is the effective force-bearing area of ​​the dynamic ring (24); The surface of the static ring (25) is sprayed or surfacing-welded with hard alloy, and the coating thickness satisfies δ=k·v, where δ is the coating thickness, k is a coefficient related to the material, and v is the pump axis speed.

5. The vertical pipeline canned motor pump according to claim 1, characterized in that: A safety reflux valve (21) is provided at the outlet of the pump body, and the safety reflux valve (21) is a spring-type structure; When the thrust formed by the product of the pressure acting on the sealing surface and the area of ​​the sealing surface is greater than the pressure of the spring of the safety reflux valve (21), the spring is compressed, the sealing surface opens, and the medium is discharged through the reflux hole; The valve body sealing surface of the safety reflux valve is a conical surface, and the valve disc sealing surface is a spherical surface. The sealing is achieved by line contact. The sealing surface and guide rail of the valve disc are nitrided or sprayed with hard alloy. The adjusting screw of the safety reflux valve is welded, fixed and sealed after the factory test, and the pre-tightening force of the adjusting screw meets F pre =k s x, where F pre is the preload force, k s is the spring stiffness and x is the spring precompression.

6. The vertical pipeline canned motor pump according to claim 1, characterized in that: The pump shaft (15) passes through the rear bearing body (16), the angular contact ball bearing (17) and the bearing cover (18); the angular contact ball bearing (17) is axially positioned in the rear bearing body (16) through the bearing cover (18); the rear bearing body (16) is rigidly connected to the outlet cover (19); and the end of the pump shaft (15) extends to the inner side of the outlet cover (19).

7. The vertical pipeline canned motor pump according to claim 1, characterized in that: The pump body further comprises a middle casing (04), a sliding bushing (07), a sliding bearing sleeve (08), an elastic sleeve (09), a shaft sleeve (10), a rear bearing body (16) and a junction box assembly (20); The middle section housing (04) is bolted to the suction cover (01) and the front bearing body (06) via a flange; the sliding bushing (07) is installed in the inner hole of the sliding bearing sleeve (08) through interference fit; the elastic sleeve (09) is nested on the outside of the sleeve (10) and elastically abuts against the rear bearing body (16); The junction box assembly (20) is sealedly connected to the motor outer shell (13) via a flange surface.

8. The vertical pipeline canned motor pump according to claim 2, characterized in that: The number n and arrangement of the ribs (23) are determined according to the size of the motor housing (13) and the medium flow requirements, satisfying the fluid mechanics model: ΔP=f(n,v',d) In the formula, ΔP is the flow channel pressure loss, v' is the medium flow velocity, and d is the flow channel equivalent diameter, so as to optimize the irregular vortex or turbulence generated by the turning and spatial size change at the outlet of the pump impeller (02).

9. The vertical pipeline canned motor pump according to claim 3, characterized in that: The sealing gap δ between the dynamic ring (24) and the static ring (25) of the dynamic sealing assembly (05) seal According to the working pressure of the pump op , speed n rot Parameter design to meet the leakage model: Where Q is the leakage, k' is the coefficient related to the medium, m is the gap index, and Δp is the pressure difference between the dynamic ring (24) and the static ring (25).

10. The vertical pipeline canned motor pump according to claim 5, characterized in that: The spring type of the safety return valve is selected according to the rated working pressure p of the pump. rat Determine the spring stiffness k s satisfy: Where A seal is the effective area of ​​the sealing surface, x op It is the additional compression of the spring under working pressure.

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