WO2020246686A1

WO2020246686A1 - Centrifugal pump directly connected to ultra-high speed permanent magnet motor

Info

Publication number: WO2020246686A1
Application number: PCT/KR2020/001710
Authority: WO
Inventors: 하기영
Original assignee: (주) 동양화공기계
Priority date: 2019-06-04
Filing date: 2020-02-06
Publication date: 2020-12-10
Also published as: KR102078042B1

Abstract

The present invention relates to a centrifugal pump directly connected to an ultra-high speed permanent magnet motor. The motor comprises: a motor housing; a rotor having an intermediate rotor part, arranged in the center of a motor housing, with permanent magnets mounted thereon, an upper rotor part extending upward from the intermediate rotor part and drawn out through an upper draw-out hole of the motor housing, and a lower rotor part extending downward from the intermediate rotor part and drawn out through a lower draw-out hole of the motor housing; and a stator arranged around the outer circumference of the intermediate rotor part, with a coil wound therearound, and fixed to an inner wall of the motor housing. An impeller is fixed to the bottom end of the lower rotor part on the same shaft. A casing discharges, through a fluid outlet, fluid passing through a fluid passage from a fluid inlet, and receives the impeller in the fluid passage through an upper opening. A stuffing box is arranged between the motor housing and the casing so as to maintain airtightness between the upper opening of the casing and the lower rotor part.

Description

Centrifugal pump directly connected to ultra-high-speed permanent magnet motor

The present invention relates to a centrifugal pump that transfers fluid by imparting pressure energy to a fluid by centrifugal force caused by rotation of an impeller.

Centrifugal pumps are the core equipment of refinery and petrochemical plants used to transfer working fluids such as hydrocarbons, basic raw materials, and synthetic raw materials to the reaction process. In the reaction process, a high pressure (high head) is required, because in order to inject the basic and intermediate fuel into the reaction tank under high pressure, the transfer pressure of the injected fuel must be much higher than the pressure inside the reaction tank.

In particular, due to the nature of the reaction process, it is necessary to inject a small amount of raw material to cause a sequential reaction. For this purpose, when the existing high flow and high pressure multi-stage centrifugal pump is applied, the amount of bypassing the raw material increases in terms of production and equipment operation. It is very inefficient. Therefore, in most oil refining and petrochemical processes, a low flow and high pressure centrifugal pump is applied to satisfy the low flow and high pressure conditions.

There is an example of a conventional centrifugal pump configured to generate a high-speed rotation by driving an increase gear with an induction motor, but due to the adoption of the speed increase gear, the efficiency is low due to the low power density, and the problem of vibration and noise is large because the volume in the vertical direction is large. Occurs frequently.

An object of the present invention is to provide a centrifugal pump that can reduce vibration and noise while improving efficiency.

The centrifugal pump according to the present invention for achieving the above object includes a motor, an upper bearing mechanism, a lower bearing mechanism, an impeller, a casing, and a stuffing box. The motor is extended upward from the motor housing and the intermediate rotor part and the intermediate rotor part arranged in the center of the motor housing with the permanent magnet mounted, and from the upper rotor part and the intermediate rotor part drawn out through the upper draw-out hole of the motor housing. A rotor extending downwardly and having a lower rotor portion drawn out through a lower lead-out hole of the motor housing, and a stator disposed around the outer circumference of the intermediate rotor portion in a coil wound state and fixed to an inner wall of the motor housing. The upper bearing mechanism is mounted in the upper withdrawal hole of the motor housing to support the rotation of the upper rotor part. The lower bearing mechanism is mounted in the lower take-out hole of the motor housing to support the rotation of the lower rotor part. The impeller is fixed on the same shaft at the lower end of the lower rotor part. The casing is disposed to be spaced downward from the motor housing, discharges through a fluid passage through a fluid inlet, and discharges through a fluid outlet, and receives an impeller through a fluid passage through an upper opening. The shaft sealing device is disposed between the motor housing and the casing to maintain airtightness between the upper opening of the casing and the lower rotor portion.

According to the present invention, since the rotor of the motor is directly connected to the impeller without an increase gear, and the rotational force of the motor is transmitted to the impeller, compared to adopting a speed increase gear, it is possible to improve efficiency by increasing the power density and reduce the volume in the vertical direction. Vibration and noise can be reduced by implementing it in a compact structure.

1 is a longitudinal sectional view of a centrifugal pump according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing an extract of the upper region of FIG. 1.

3 is a longitudinal cross-sectional view showing an extract of the lower region of FIG. 1.

4 is a plan view of the impeller.

5 is a plan view of the casing.

6 is a perspective view of a circulation fan.

7 is a perspective view of a cooling fan.

8 is a cross-sectional view of the centrifugal pump shown in FIG. 1.

9 is a cross-sectional view for explaining the operation of the circulation fan and the cooling fan.

The present invention will be described in detail with reference to the accompanying drawings as follows. Here, the same reference numerals are used for the same configuration, and repeated descriptions and detailed descriptions of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted. Embodiments of the present invention are provided to more completely describe the present invention to those with average knowledge in the art. Accordingly, the shapes and sizes of elements in the drawings may be exaggerated for clearer explanation.

1 is a longitudinal sectional view of a centrifugal pump according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing an extract of the upper region of FIG. 1. 3 is a longitudinal cross-sectional view showing an extract of the lower region of FIG. 1. 4 is a plan view of the impeller. 5 is a plan view of the casing.

1 to 5, the centrifugal pump according to an embodiment of the present invention includes a motor 100, an upper bearing mechanism 200, a lower bearing mechanism 300, an impeller 400, and It includes a casing 500, and a stuffing box 600.

The motor 100 includes a motor housing 110, a rotor 120, and a stator 130. The motor housing 110 may include a housing body 111, an upper housing cover 112, and a lower housing cover 115. The housing body 111 has an inner space, and the upper and lower sides are opened.

The upper housing cover 112 is fixed around the upper opening by bolting or the like while covering the upper opening of the housing body 111. The upper housing cover 112 has an upper withdrawal hole through which the upper rotor part 122 is withdrawn.

The upper housing cover 112 may be configured in a form in which the inner cover part 113 and the outer cover part 114 are stacked up and down and fixed by bolting or the like. A fan accommodation space 112a for accommodating a circulation fan 700 to be described later may be formed between the inner cover part 113 and the outer cover part 114.

The inner cover 113 includes air intakes 113a for inhaling air from the inner space of the housing body 111 to the fan receiving space 112a, and the inner space of the housing body 111 from the fan receiving space 112a. It has air outlets (113b) to discharge the air. The air intakes 113a may be located adjacent to the outer periphery of the upper rotor part 122, and the air outlets 113b may be located adjacent to the inner wall of the housing body 111.

The lower housing cover 115 is fixed around the lower opening by bolting or the like while covering the lower opening of the housing body 111. The lower housing cover 115 has a lower withdrawal hole through which the lower rotor part 123 is withdrawn.

The rotor 120 includes an intermediate rotor portion 121, an upper rotor portion 122 and a lower rotor portion 123. The intermediate rotor unit 121 is disposed in the center of the motor housing 110 with a permanent magnet mounted thereon. The intermediate rotor unit 121 may have a constant outer diameter and may embed a permanent magnet.

The upper rotor part 122 extends upward from the intermediate rotor part 121 and is drawn out through the upper withdrawal hole of the motor housing 110. The upper rotor part 122 may be formed in a form in which the outer diameter gradually decreases toward the upper side.

The lower rotor part 123 extends downward from the intermediate rotor part 121 and is drawn out through the lower withdrawal hole of the motor housing 110. The lower rotor part 123 may be formed in a form in which the outer diameter gradually decreases toward the lower side.

The intermediate rotor portion 121, the upper rotor portion 122, and the lower rotor portion 123 are formed of separate members and are fitted together in the sleeve 124, thereby configuring an integrated rotor 120. Of course, the intermediate rotor portion 121, the upper rotor portion 122, and the lower rotor portion 123 are manufactured as one member, so that an integrated rotor 120 may be configured.

The stator 130 is disposed around the outer circumference of the intermediate rotor unit 121 while the coil is wound, and is fixed to the inner wall of the motor housing 110. In a state in which a magnetic field is generated by the permanent magnet of the rotor 120, when current is supplied to the coil of the stator 130, the rotor 120 is rotatable by an electromagnetic force.

The stator 130 has teeth formed along the circumferential direction on the surface facing the rotor 120, and slots are formed between the teeth. The coils can be installed to wind each tooth. The stator 130 generates a rotating magnetic field for rotating the rotor when a current flows through the coil.

These motors 100 include the number of slots, turns per slot, winding diameter, slot area, number of parallel circuits, number of wires, space factor, phase resistance, synchronous inductance, counter electromotive force constant, permanent magnet diameter, rotor diameter, stator It can be configured with an ultra-high-speed permanent magnet motor of 12,000 rpm or more according to settings such as inner diameter, stator outer diameter, stator axial length, sleeve thickness, air gap, tooth thickness, and slot opening.

The upper bearing mechanism 200 is mounted in the upper withdrawal hole of the motor housing 110 to support the rotation of the upper rotor part 122. The upper bearing mechanism 200 may include an upper bearing 210 and an upper bearing housing 220. The upper bearing 210 supports rotation of the upper rotor part 122. The upper bearing 210 may be formed of a rolling bearing.

The upper bearing housing 220 is fixed to the upper withdrawal hole of the motor housing 110 while being supported by surrounding the outer circumference of the upper bearing 210. The upper bearing housing 220 may be formed in a form in which the upper part partially covers the outer cover part 114 with the lower part inserted into the upper withdrawal hole of the outer cover part 114. The upper bearing housing 220 may be fixed to the outer cover portion 114 by bolting or the like.

The upper bearing 210 may be supplied with oil for lubrication through the upper oil passage 114a. The upper oil passage 114a may be formed to supply oil from the inner boss 231 to the upper bearing 210 and to discharge oil falling by gravity to the outer cover portion 114. The upper oil passage 114a may be supplied with oil by an oil jet method or by mixing and spraying air with oil.

The upper oil passage 114a may be sealed by a first oil seal 230 disposed above the upper bearing mechanism 200 and a second oil seal 240 disposed below the upper bearing mechanism 200. have. The inner boss 231 may be fixed to the upper side of the outer cover part 114 by bolting or the like while penetrating the upper rotor part 122 through a hollow. The first oil seal 230 is fixed to the hollow inner circumferential surface of the inner boss 231 and contacts the outer circumferential surface of the upper rotor part 122 to maintain airtightness between the inner boss 231 and the upper rotor part 122 I can.

Since the outer boss 232 penetrates the upper rotor part 122 through the hollow and is fixed to the upper side of the inner boss 231 by bolting, it is possible to prevent the first oil seal 230 from being separated from the upper side. The first oil seal 230 may be formed of a labyrinth seal. Labyrinth seal is a type of seal that reduces the amount of leakage by receiving a pressure drop every time a fluid passes through narrow gaps several times.

The second oil seal 240 contacts the outer circumferential surface of the upper rotor part 122 while being fixed to the inner circumferential surface of the upper withdrawal hole of the inner cover part 113, so that between the inner cover part 113 and the upper rotor part 122 Can keep the confidentiality of. The second oil seal 240 may be formed of a labyrinth seal.

The lower bearing mechanism 300 is mounted in the lower withdrawal hole of the motor housing 110 to support the rotation of the lower rotor part 123. The lower bearing mechanism 300 may include lower bearings 310 and lower bearing housings 320. The lower bearings 310 are arranged in two rows up and down to support the rotation of the lower rotor part 123. The lower bearing 310 may be formed of a rolling bearing.

The lower bearing housing 320 is fixed to the lower lead-out hole of the motor housing 110 while surrounding and supporting the lower bearings 310. The lower bearing housing 320 may be fixed to the lower housing cover 115 by bolting or the like while being inserted into the lower lead-out hole of the lower housing cover 115.

The lower bearing 310 may be supplied with oil for lubrication through the lower oil passage 115a. The lower oil passage 115a supplies oil from the upper portion of the lower housing cover 115 to the lower bearing 310 in the upper row, and the oil falling through the lower bearing 310 in the lower row by gravity is transferred to the lower housing cover 115 ) Can be formed to be discharged to the bottom of the. The lower oil passage 115a may be supplied with oil by an oil jet method, or may be supplied with oil by mixing and spraying air with oil.

The lower oil passage 115a may be sealed by a third oil seal 330 disposed above the lower bearing mechanism 300 and a shaft sealing device 600 disposed below the lower bearing mechanism 300. The third oil seal 330 is disposed above the bearings 310 in the upper row and contacts the outer circumferential surface of the lower rotor part 123 while being fixed to the lower housing cover 115, so that the lower housing cover 115 and Airtightness between the lower rotor parts 123 can be maintained. The third oil seal 330 may be formed of a labyrinth seal.

The impeller 400 is fixed to the lower end of the lower rotor part 123 on the same axis. As the impeller 400 rotates together with the lower rotor part 123, the velocity energy by centrifugal force is applied to the sucked fluid. The impeller 400 may have a structure in which the wings 402 are arranged in the same shape along the outer circumference of the hub 401.

The inducer 410 may be fixed to the lower side of the impeller 400 on the same axis. The inducer 410 is disposed in front of the impeller 400 based on the suction direction of the fluid and rotates together with the lower rotor part 123, thereby preventing cavitation. The inducer 410 may have a structure in which the wings 412 are formed in a spiral direction on the outer peripheral surface of the hub 411.

The inducer 410 includes a first inducer coupling portion 413 extending upward from the hub 411 and a second inducer coupling portion 414 extending upward from the first inducer coupling portion 413. Can include. The first inducer coupling portion 413 is coupled in a state through the hub 401 of the impeller 400 in a buried key manner, thereby preventing a relative rotational slip between the inducer 410 and the impeller 400. Can be prevented.

The second inducer coupling portion 414 may be screwed into a lower screw groove of the lower rotor portion 123 by forming a screw tab on the outer periphery. The screw coupling direction of the second inducer coupling part 414 and the lower rotor part 123 is set in a direction opposite to the rotational direction of the lower rotor part 123, so that the second inducer coupling part 414 and the lower rotor The part 123 may be prevented from loosening when the lower rotor part 123 is rotated.

A shroud 420 may be fixed to the fluid passage 530 of the casing 500 with the inducer 410 surrounding the outer circumference. The shroud 420 has a hollow of a certain inner diameter. The shroud 420 may be formed in a form in which the lower part has a certain outer diameter, and the outer diameter is expanded in two stages as the upper part goes upward. The casing 500 has a two-stage jaw for seating the upper portion of the shroud 420 in two stages around the pumping space 531. The shroud 420 may be mounted in two stages around the pumping space 531 of the casing 500 and may be fixed by bolting or the like.

The casing 500 is disposed to be spaced apart downward from the motor housing 110. The casing 500 is discharged through the fluid passage 530 through the fluid inlet 510 and the fluid outlet 520, and accommodates the impeller 400 through the fluid passage 530 through the upper opening. The casing 500 may have a fluid inlet 510 and a fluid outlet 520 formed on an outer surface thereof, and a fluid passage 530 is formed in a spiral shape therein to be connected to the fluid inlet 510 and the fluid outlet 520 . That is, the casing 500 may be formed of a volute casing. The casing 500 may have a flange formed around each of the fluid inlet 510 and the fluid outlet 520.

The casing 500 has a pumping space 531 accommodating the impeller 400 and the inducer 410 through an upper opening in the middle of the fluid passage 530. In the casing 500, a fluid passage 530 between the outlet of the impeller 400 and the fluid outlet 520 may be formed as a diffuser. The diffuser converts the velocity energy of water applied by the impeller 400 into the pressure energy of water.

The shaft sealing device 600 is disposed between the motor housing 110 and the casing 500 to maintain airtightness between the upper opening of the casing 500 and the lower rotor part 123. The shaft sealing device 600 has a structure in which the seal 610 is mounted on the seal housing 620. The seal housing 620 is disposed between the motor housing 110 and the casing 600 while penetrating the lower rotor part 123 through the hollow. The seal housing 620 is fixed to the motor housing 110 and the casing 500 by bolting or the like. The seal housing 620 covers the upper opening of the casing 500 with the lower part passing through the lower rotor part 123.

The seal housing 620 may be formed in a form in which the outer diameter decreases in multiple stages toward the lower side. The casing 500 may be formed in a shape having a jaw for seating the seal housing 620 in multiple stages around the upper opening. Therefore, the casing 500 and the seal housing 620 can be maintained in a stably coupled state.

The seal 610 contacts the outer circumferential surface of the lower rotor part 123 while being fixed to the hollow inner circumferential surface of the seal housing 620, thereby maintaining airtightness between the seal housing 620 and the lower rotor part 123. Seal 610 may be made of a mechanical seal (mechanical seal). A mechanical seal is a surface-contact type seal that consists of two perturbation surfaces perpendicular to the rotation axis, one side rotates with the rotation axis, and continuously maintains the sealing of the rotation axis by the tension of the spring or the pressure of the fluid. In mechanical seals, lubrication of the seal surface is achieved by a self-formed fluid film (0.025~0.25㎛).

According to the above-described centrifugal pump, since the rotor 120 of the motor 100 is directly connected to the impeller 400 without an increase gear, the rotational force of the motor is transmitted to the impeller 400, so that the power density is increased compared to employing an increase gear. By increasing the efficiency, it is possible to improve the efficiency, and by implementing a compact structure by reducing the volume in the vertical direction, vibration and noise can be reduced.

Meanwhile, the circulation fan 700 is fixed to the upper rotor part 122 on the same axis while being disposed inside the motor housing 110 and rotates, thereby circulating the air inside the motor housing 110. As the cooling fan 800 is disposed on the outside of the motor housing 110 and is fixed to the upper rotor part 122 on the same axis and rotates, ambient air may be sent to the outer wall of the motor housing 110.

When the centrifugal pump transfers a fluid such as gas or steam that may cause an explosion or fire, the motor 100 is made of an explosion-proof motor and has a closed structure in which the inflow of external cooling air is blocked. When the motor 100 is driven, heat is generated from the permanent magnet of the rotor 120 and the coil of the stator 130 to increase the internal temperature. When the inside of the motor 100 is excessively overheated, a problem such as burning of the motor 100 may occur. Therefore, the temperature of the permanent magnet inside the motor 100 needs to be maintained at a set temperature, for example, 140° C. or less.

In this situation, the circulation fan 700 alleviates the temperature imbalance inside the motor 100, and the cooling fan 800 sets the internal temperature of the motor 100 by removing heat inside the motor 100 to the outside. Allows you to lower it below the temperature.

As shown in FIG. 6, the circulation fan 700 may be formed of a centrifugal type that sucks air from the center and sends it in the circumferential direction. The circulation fan 700 is formed in a form in which the blades 720 are arranged in the same shape along the circumferential direction on the hollow disk 710.

As shown in FIG. 7, the cooling fan 800 may be of an axial flow type that transports air in the same direction as the axial direction. The cooling fan 800 has a structure in which the blades 820 are arranged in the same shape along the outer circumference of the hub 810. The blades 820 of the cooling fan 800 are set to suck air from the upper part and send it to the lower part when the upper rotor part 122 rotates.

Referring back to FIGS. 1 and 2, the motor 100 may include a top cap 116 accommodating the cooling fan 800. The top cap 116 has an inner space and has an opening formed at the lower side. The top cap 116 is fixed to the upper housing cover 112 around the lower opening by bolting or the like in a state in which the cooling fan 800 is accommodated in the inner space.

The top cap 116 may have air intake ports 116a that suck air in the upper side. The upper housing cover 112 may have air outlets 112b for discharging air in the top cap 116 at a portion adjacent to the top cap 116. The air outlets 112b may be formed to discharge air in the top cap 116 and guide it to the outer surface of the housing body 111.

As shown in FIG. 8, the housing body 111 may be formed by protruding radiating fins 111a from the outer surface. The radiating fins 111a may be arranged at regular intervals along the outer periphery of the housing body 111. Each of the heat dissipation fins 111a may be formed in a form extending in a predetermined cross-sectional area along the vertical direction of the housing body 111. The radiating fins 111a expand the cooling surface of the housing body 111 in contact with air, thereby increasing the heat dissipation performance of the housing body 111 by air cooling.

The operation of the circulation fan 700 and the cooling fan 800 will be described with reference to FIG. 9 as follows.

When the rotor 120 rotates when the motor 100 is driven, the circulation fan 700 and the cooling fan 800 rotate together with the upper rotor part 122 of the rotor 120. At this time, the circulation fan 700 sucks air from the inner space of the housing body 111 through the air inlet 113a of the inner cover 113 adjacent to the outer circumference of the upper rotor part 122, and then in the circumferential direction. And discharged to the inner space of the housing body 111 through the air outlets 113b of the inner cover 113 adjacent to the inner wall of the housing body 111. Accordingly, the air in the housing body 111 is circulated by the circulation fan 700 to alleviate the temperature imbalance inside the motor 100.

At the same time, the cooling fan 800 sucks in through the air intake openings 116a of the top cap 116 and then discharges it in the axial direction and discharges it through the air outlets 112b of the upper housing cover 112. The exhausted air flows along the outer surface of the housing body 111 and cools through heat exchange, thereby removing heat from the inside of the motor 100 to the outside. Accordingly, the cooling fan 800 can lower the internal temperature of the motor 100 together with the circulation fan 700 to a set temperature or less.

The present invention has been described with reference to one embodiment shown in the accompanying drawings, but this is only illustrative, and those of ordinary skill in the art will understand that various modifications and other equivalent embodiments are possible therefrom. I will be able to. Accordingly, the true scope of protection of the present invention should be determined only by the appended claims.

Claims

The motor housing, the intermediate rotor part arranged in the center of the motor housing with a permanent magnet mounted, and the upper rotor part and the intermediate rotor extended upwardly from the intermediate rotor part and drawn out through the upper withdrawal hole of the motor housing A rotor extending downward from the part and having a lower rotor part drawn out through a lower drawing hole of the motor housing, and a stator disposed around the outer circumference of the intermediate rotor part in a coil wound state and fixed to the inner wall of the motor housing. Motor to do;

An upper bearing mechanism mounted in an upper withdrawal hole of the motor housing to support rotation of the upper rotor portion;

A lower bearing mechanism mounted in a lower withdrawal hole of the motor housing to support rotation of the lower rotor portion;

An impeller fixed on the same axis at the lower end of the lower rotor part;

A casing disposed to be spaced downward from the motor housing, discharging through a fluid passage through a fluid inlet, and receiving the impeller through a fluid passage through an upper opening; And

A shaft sealing device disposed between the motor housing and the casing to maintain airtightness between an upper opening and a lower rotor portion of the casing;

Centrifugal pump comprising a.
The method of claim 1,

An inducer fixed to the lower side of the impeller in the same axis,

And a shroud fixed to the fluid passage of the casing while surrounding the inducer around the outer periphery.
The method of claim 1,

The lower bearing mechanism,

Lower bearings arranged in two rows up and down to support rotation of the lower rotor part,

And a lower bearing housing fixed to a lower withdrawal hole of the motor housing while surrounding and supporting the outer peripheries of the lower bearings.
The method of claim 1,

A circulation fan disposed inside the motor housing and fixed to the upper rotor part on the same axis to circulate the air inside the motor housing as it rotates,

And a cooling fan disposed on the outside of the motor housing and fixed to the upper rotor part in the same axial direction to rotate the surrounding air toward the outer wall of the motor housing.