JPH0578991U - Shaft whirl prevention device for multi-stage submerged motor pump - Google Patents

Abstract

(57) [Summary] [Purpose] To reliably suppress whirling of the pump shaft for a long period of time, prevent irregular wear of the bush over time, and extend the life of the bush. [Constitution] An inducer having an upper part formed in a motor part 1 and a lower part formed in a pump part 2, and an impeller 22 in the middle of a pump shaft 23 extending from the motor part to a lower pump part, and an axial flow impeller at the lower end. In a vertical multi-stage submerged motor pump having 25, a hydrostatic bearing 30 for bearing the pump shaft is provided between the lowermost impeller and the axial flow impeller, and the hydrostatic bearing is a bearing. A pressure chamber 31 is provided on the back side of the surface side, the pressure chamber and the bearing surface side are communicated by an orifice 32, and a part of the liquid discharged from the pump portion is supplied to the pressure chamber. And

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a shaft whirl-stopping device for a vertical multistage submerged motor pump used for pressurizing low-temperature liquids such as LNG, LPG, ethylene, propylene, and ammonia.

[0002]

[Prior Art]

 This type of pump has an upper part formed in the motor part and a lower part formed in the pump part, and is used while the whole is immersed in the handling liquid. The motor part has a stator, a rotor, a shaft connected to the rotor, an upper bearing and a lower bearing for supporting the shaft, and a pressurized liquid passage in the motor housing. A part of the liquid cools the motor and lubricates the bearing. The above shaft extends downward as a pump shaft and reaches the lower end of a pump casing connected to the lower end of the motor housing. The pump portion is provided with an impeller in the middle of the pump shaft, a suction port at the lower end of the pump casing, and an inducer having an axial impeller attached at the lower end of the pump shaft. The pump shaft is supported in the pump casing on the casing side via a bush.

[0003]

[Problems to be solved by the device]

 In the conventional vertical multi-stage submerged motor pump described above, whirling vibration of the shaft may occur, which may cause the bush supporting the pump shaft to wear in a short period of time. This extremely large wear of the bush leads to a pump accident, so it is necessary to detect it early and replace the bush. However, the wear of the bush is not always proportional to the pump usage time. Therefore, there is also a problem that it is not easy to control the wear of the bush. In addition, there is an attempt to support the upper part of the inducer near the lower end of the shaft to the casing through the bush in order to effectively suppress the whirling of the shaft against the wear of the bush, but the bush also has a problem in the front. As with the bushes mentioned above, they may wear out in a short period of time, and the same problem remains.

Therefore, an object of the present invention is to reliably suppress whirling of the pump shaft for a long period of time, prevent irregular wear of the bush over time, and extend the life of the bush.

[0005]

[Means for Solving the Problems]

 According to the means of the invention, an upper part is formed in a motor part and a lower part is formed in a pump part, an impeller is provided in the middle of a pump shaft extending from the motor part to a lower pump part, and an inducer is formed of an axial impeller at a lower end. In a vertical multi-stage submerged motor pump having a hydrostatic bearing for bearing the pump shaft, the hydrostatic bearing is provided between the lowermost impeller and the axial flow impeller. Is characterized in that a pressure chamber is provided in the back part of the device, the pressure chamber and the bearing surface side are communicated with each other by an orifice, and a part of the liquid discharged from the pump part is supplied to the pressure chamber.

[0006]

[Action]

 By supplying the pressurized liquid from the pump unit as the lubricating liquid to the hydrostatic bearing, the lower end of the pump shaft is supported by the pressurized liquid, and the lower end of the pump shaft is prevented from swinging around. . In particular, due to the presence of the pressure chamber, the follow-up property that quickly compensates for the pressure drop on the bearing surface during shaft runout is good, and this effectively suppresses whirling of the shaft. No wear occurs on the part of the hydrostatic bearing that supports the pump shaft.

[0007]

【Example】

 An embodiment of this invention will be described with reference to the drawings. In FIG. 1, 1 is a motor part and 2 is a pump part. The motor unit 1 includes a motor housing 10 in which a stator 11, a rotor 12, a shaft 13 coupled to a rotor, an upper bearing 14 and a lower bearing 15 for supporting the shaft 13, a pressurized liquid passage 16 and the like are provided. Is. In the motor unit 1, cooling of the motor unit and lubrication of the bearings 14 and 15 are performed by a part of the handling liquid pressurized by the pump unit 2. The bearings 14 and 15 are radial ball bearings. In the figure, 51 is a power supply line, 17 is a balance drum, and 18 is a lower bearing housing.

The pump section 2 includes a pump casing 20 coupled to a lower end of the motor housing 10, a diffuser 21, an impeller 22 in the casing 20, a pump shaft 23 extending downward from the shaft 13, and a lower end of the casing 20. The suction port 24 is formed, and the inducer 25 provided at the suction port 24 is provided. The impeller 22 is attached to the pump shaft 23, the inducer 25 is an axial flow impeller attached to the lower end of the pump shaft, and the pump shaft 23 is supported on the casing 20 side via a bush 26. The outlet 27 of the pump unit 2 is connected to the lower end of the liquid passage 16 of the motor unit 1.

The above-described configurations of the motor unit 1 and the pump unit 2 are the same as those of the conventional vertical multi-stage sub-merged motor pump described above. The difference from the conventional one is that a static pressure bearing 30 for bearing the pump shaft 23 is provided between the lowest part of the impeller 22 of the pump section 2 and the axial flow impeller of the inducer 25, and the static pressure A part of the liquid discharged from the pump unit 2 is supplied to the bearing 30.

As shown in the enlarged view of FIGS. 2 and 3, the hydrostatic bearing 30 includes a pressure chamber 31, an orifice 32, and a lubricating liquid reservoir 33. The static pressure bearing 30 radiates from the cylindrical portion 36 and the cylindrical portion 36. It is supported on the side of the casing 20 by a bearing support portion including a support 37 extending in a line and connected to the casing. The pressure chambers 31 are formed in the bearing body so as to be continuous in the circumferential direction, the lubricating liquid reservoirs 33 are formed in the circumferential surface of the bearing body at regular intervals in the circumferential direction, and the orifices 32 are provided in the pressure chambers 31 and the respective lubrication chambers. The liquid pool 33 is communicated. The orifice 32 is formed to have a diameter of about 5 mm, for example. The dimensions of the orifice 32 and other parts are determined so that the pressure in the pressure chamber 31 is approximately 2 and the pressure in the lubricating liquid reservoir 33 is approximately 1. A part of the liquid discharged from the pump section 2 is supplied to the pressure chamber 31. That is, another passage 34 branched from the pressurized liquid passage 16 of the motor housing 10 is formed by a pipe, which is connected to the bearing body and opened in the pressure chamber 31.

This multi-stage submerged motor pump is installed near a tank in combination with a pot 40, for example, as shown in FIG. 1, and is used when the low temperature liquid in the tank is transferred to another place. To be done. The pot 40 is installed in the pit and is filled with a heat insulating material on the outer side thereof, and the inside is connected to a tank containing the liquid to be handled through an inlet 41 and a gas vent 42. It is supposed to flow into. Therefore, the motor unit 1 and the pump unit 2 are used in a state where the whole is soaked in the handling liquid. In the figure, reference numeral 50 is a discharge port that communicates with the liquid passage 16 and is connected to a transfer pipe. 43 is a pot support leg, and 44 is a drain drain.

When the pump shaft 23 is rotationally driven by the motor unit 1, the liquid to be handled flowing into the pot 40 is pressurized while passing through the suction port 24 to the outlet 27 of the pump unit 2, and the passage 16 Through the discharge port 50. Then, a part of the pressurized liquid is supplied into the pressure chamber 31 through the passage 34 and is supplied to the lubricating liquid reservoir 33 through the orifice 32. As a result, the pump shaft 23 is supported via the pressurized handling liquid, and whirling is prevented. For example, when the pump shaft 23 swings to one side, the gap between the shaft and the bearing body becomes narrow on one side and wide on the other side. Since the hydraulic pressure decreases on the wide side and increases on the narrow side, the acting force due to the hydraulic pressure tries to push back from the swung side of the pump shaft 23. Further, on the side where the pump shaft 23 is pushed back and the hydraulic pressure is low, the liquid is promptly supplied from the pressure chamber 31 to the lubricating liquid reservoir 33 via the orifice 32, and the pump shaft 23 appropriately opposes without being delayed. By these actions, the runout of the pump shaft 23 is always suppressed, and the runout is prevented. Therefore, since the load due to whirling does not act on the bush 26 supporting the pump shaft 23 on the pump casing 20 side, early wear of the bush 26 is eliminated. Further, a part of the pressurized liquid to be handled passes through the inside of the motor unit 1, cools, and finally merges with the pressurized liquid in the passage 16. The arrow in the figure indicates the moving direction of the handled liquid.

Although the passage 34 is formed by the pipe in the above embodiment, it may be formed within the wall thickness of the pump casing 20. Further, the number of the lubricating liquid reservoirs 33 and the orifices 32 is not limited to the four shown in the drawing, but may be an appropriate number of three or more and may be arranged at equal intervals in the circumferential direction.

[0014]

[Effect of the device]

 According to this invention, since the lower end of the pump shaft of the vertical multi-stage submerged motor pump is supported by the hydrostatic bearing, there is no wear and the whirling of the lower end of the pump shaft can be reliably suppressed for a long period of time. This has the effect of reliably preventing premature wear of the bush supporting the shaft.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a vertical cross section of a main part of the embodiment.

3 is a cross-sectional view taken along the line AA of FIG.

[Explanation of symbols]

 1 Motor Section 2 Pump Section 22 Impeller 23 Pump Shaft 25 Inducer 30 Static Pressure Bearing 31 Pressure Chamber 32 Orifice 33 Lubrication Station Reservoir 34 Passage

Claims (1)

[Scope of utility model registration request] 1. An upper part is formed in a motor part and a lower part is formed in a pump part, and an impeller is provided in the middle of a pump shaft extending from the motor part to a lower pump part and an inducer made of an axial flow impeller is provided at a lower end. In a vertical multi-stage submerged motor pump, a static pressure bearing for bearing the pump shaft is provided between the lowermost one of the impellers and the axial flow impeller, and the static pressure bearing has a back surface on the bearing surface side. A pressure chamber is provided in the pressure chamber, the pressure chamber and the bearing surface side are communicated with each other by an orifice, and a part of the liquid discharged from the pump portion is supplied to the pressure chamber. A shaft runout prevention device for a motor pump.