JPH0571496A - Shaft centrifugal whirling prevention device for multistage submerged motor pump - Google Patents

Abstract

PURPOSE:To enable a fluid bearing free from wear to be adopted with the application of a simple structure by providing an outer ring at an inducer at the lower end of the shaft of a multistage submerged motor pump, and supporting the ring with the fluid bearing employing a pressurized part of liquid after the outlet of the pump to handle the liquid. CONSTITUTION:A multistage submerged motor pump has an motor section 1 above and a pump section 2 below, and an impeller 22 is provided at the intermediate section of a pump shaft 23 extended from the upper motor section 1 to the lower pump section 2. In addition, the lower end of the shaft 23 is fitted with an inducer 25 comprising an axial flow impeller. In this case, the inducer 25 is fitted with an outer ring 30, and the casing 20 of the pump section 2 is fitted with a wear ring section 31 in such a way as enclosing the external surface of the outer ring 30 via a fine gap. In addition, constitution is so made as to supply a part of delivery liquid from the pump section 2 to the gap. Namely, another passage 34 branched from the passage 16 of a motor housing 10 for pressurized liquid is formed with a pipe, and this pipe is connected to the wear ring section 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft whirl prevention device for a vertical multi-stage submerged motor pump used for pressurizing low temperature liquids such as LNG, LPG, ethylene, propylene and ammonia.

[0002]

2. Description of the Related Art In this type of pump, the upper part is the motor part,
The lower part is formed in the pump part, and the whole is used in a state of being immersed in the handling liquid. The motor part is provided with a stator, a rotor, a shaft connected to the rotor, upper and lower bearings for supporting the shaft, a pressurized liquid passage, etc. in the motor housing. The motor part is cooled and the bearing is lubricated by a part of. The shaft extends downward as a pump shaft and reaches a lower end of a pump casing connected to a lower end of the motor housing. And
The pump portion has an impeller provided in the middle of the pump shaft, a suction port formed at the lower end of the pump casing, and an inducer having an axial flow 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]

In the conventional vertical multi-stage submerged motor pump described above, whirling vibration of the shaft may occur, which causes the bush supporting the pump shaft to wear in a short period of time. There is a problem. This excessive wear of the bush leads to a pump damage 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, aiming to effectively suppress whirling of the shaft against wear of this bush,
There is also an attempt to support the upper part of the inducer near the lower end of the shaft to the casing via a bush, but that bush may also wear in a short period of time like the above-mentioned bush, and eventually the same problem occurs. Remain.

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

[0005]

According to the means of the present invention, 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 a lower end is formed. In a vertical multi-stage submerged motor pump having an inducer composed of an axial flow impeller, an outer ring is provided on the inducer, and the casing of the pump section is dressed so as to surround the outer ring with a minute gap. A ring portion is provided, and a part of the liquid discharged from the pump portion is supplied between the inner peripheral surface of the wear ring portion and the outer peripheral surface of the outer ring.

[0006]

By supplying the pressurized liquid between the outer ring and the wear ring, the outer ring at the lowermost end of the pump shaft is supported by the fluid bearing, and the lower end of the pump shaft touches around. Suppress.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present 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 stator 11 in a motor housing 10,
Rotor 12, shaft 13 coupled to the rotor, upper bearing 14 and lower bearing 15 supporting shaft 13, pressurized liquid passage 1
6 and the like are provided. This motor unit 1 is a pump unit 2
The motor part is cooled and the bearings 14 and 15 are lubricated by a part of the handled liquid pressurized by. The bearings 14 and 15 are radial ball bearings. In the figure, 16 is a power supply line, 17 is a balance drum, and 18
Is the lower bearing housing.

The pump portion 2 is a pump casing 20 connected to the lower end of the motor housing 10, and the casing 2 thereof.
Zero diffuser 21, impeller 22, and shaft 13
It has a pump shaft 23 extending downward from the suction port 24, a suction port 24 formed at the lower end of the casing 20, an inducer 25 provided at the suction port 24, and the like. The impeller 22 is attached to the pump shaft 23, and the inducer 25 is an axial flow impeller attached to the lower end of the pump shaft.
3 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-mentioned configurations of the motor unit 1 and the pump unit 2 are the same as those of the conventional vertical multistage submerged motor pump described above. As shown in an enlarged view in FIGS. 2 and 3, the difference from the conventional one is that an inducer 25 of this pump is provided with an outer ring 30 and the outer ring 30 has a peripheral surface of 0.1 to 0.8 m.
The pump portion 2 is surrounded by a minute gap of about m.
The casing 20 is provided with a wear ring portion 31, and a part of the liquid discharged from the pump portion is supplied between the inner peripheral surface 32 of the wear ring portion 31 and the outer ring peripheral surface 33. That is, another passage 34 branched from the passage 16 for the pressurized liquid of the motor housing 10 is formed by a pipe, and this is connected to the wear ring portion 31 so that the inner peripheral surface 32 of the wear ring portion 31 has three locations. Is opened as the supply port 35. As a result, a fluid bearing using the liquid to be handled is formed at the lower end of the pump shaft 23.

This multi-stage submerged motor pump is
For example, as shown in FIG. 1, it is installed in the vicinity of the tank in combination with the pot 40 and is used when the low temperature liquid in the tank is transferred to another place. This pot 40
Is installed in the pit and is filled with a heat insulating material on the outside, and the inside is connected to the tank containing the liquid to be handled through the inlet 41 and the gas vent 42.
It is designed to flow into 0. Therefore, the motor unit 1
And the pump part 2 is used in a state where the whole is immersed in the handling liquid. In the figure, reference numeral 50 is a discharge port communicating with the liquid passage 16, to which a transfer pipe is connected. 43 is a pot support leg,
Reference numeral 44 is a drain-free type.

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 from the supply port 35 through the passage 34 between the outer peripheral surface 33 of the outer ring and the inner peripheral surface 32 of the wear ring. As a result, the outer ring 30 is supported via the thin layer of the handling liquid, and whirling 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. In addition, a part of the pressurized handling liquid 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 of a pipe in the above embodiment, it may be formed within the thickness of the pump casing 20. Further, the number of supply ports 35 is not limited to three,
As an appropriate number of two or more, they may be arranged at equal intervals in the circumferential direction.

[0013]

According to the present invention, the outer ring is provided on the inducer at the lower end of the pump shaft of the vertical multi-stage submerged motor pump, and the outer ring is provided with the pressurized liquid after the pump outlet of the liquid to be handled. Since it is supported by the used fluid bearing, a fluid bearing structure with a relatively simple structure and no wear can be adopted, and whirling of the lower end of the pump shaft can be reliably suppressed for a long period of time. The effect of reliably preventing early wear is obtained.

[Brief description of drawings]

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

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor part 2 Pump part 22 Impeller 23 Pump shaft 25 Inducer 30 Outer ring 31 Wear ring part 34 Passage 35 Supply port

Claims (1)

[Claims] 1. An inducer having an upper part formed as a motor part and a lower part formed as a pump part, an impeller provided in the middle of a pump shaft extending from the motor part to a lower pump part, and an axial flow impeller at the lower end. In the vertical multi-stage submerged motor pump having, an outer ring is provided on the inducer, and a wear ring section is provided on the casing of the pump section so as to surround the outer ring with a minute gap, and the inner circumference of the wear ring section is provided. A shaft whirling prevention device for a multi-stage submerged motor pump, characterized in that a part of the liquid discharged from the pump portion is supplied between the surface and the outer circumferential surface of the outer ring.