WO2017138472A1

WO2017138472A1 - Suction casing for multi-stage submersible pump, and multi-stage submersible pump

Info

Publication number: WO2017138472A1
Application number: PCT/JP2017/004148
Authority: WO
Inventors: 和也平本; 前田　毅
Original assignee: 株式会社荏原製作所
Priority date: 2016-02-10
Filing date: 2017-02-06
Publication date: 2017-08-17
Also published as: CN108603507B; JP2017141735A; CN108603507A; BR112018016288A2; TWI710704B; BR112018016288B1; TW201730436A; JP6624962B2

Abstract

A multi-stage submersible pump in which a preliminary whirl is caused in the flow of water into the pump without attaching a special member. A suction casing for a multi-stage submersible pump which handles liquid is provided with a plurality of casing bodies which extend along an axis and which are arranged at intervals in a circumferential direction about the axis. The gaps between the plurality of casing bodies form a plurality of suction openings along the circumferential direction. The plurality of suction openings are formed such that, in a cross section perpendicular to the axis, each of the plurality of suction openings has a liquid inflow direction different from a direction toward the axis, and such that the liquid inflow direction in each of the plurality of suction openings is a direction defined by rotating the liquid inflow direction of one of the plurality of suction openings by a predetermined angle about the axis.

Description

Suction casing for multistage submersible pump and multistage submersible pump

The present invention relates to a suction casing for a multistage submersible pump.

Multi-stage submersible pumps that handle liquids (for example, submersible pumps for deep wells) are known. Such a multistage submersible pump is configured by connecting a plurality of casings in which an impeller is housed in the axial direction. For example, the following Patent Document 1 has a suction casing fixed to the submersible motor, a guide vane, a plurality of intermediate casings stacked in a multistage manner on the upper portion of the suction casing, and attached to the uppermost intermediate casing. A multi-stage submersible pump comprising a discharge casing is disclosed. In this multistage submersible pump, the water sucked from the suction casing flows linearly into the intermediate casing along the axial direction.

JP-A-6-323291 JP 2005-320869 A Published Utility Showa 54-24103

In the multistage submersible pump as described above, it is generally a problem how to suppress the loss and improve the pump efficiency. In order to suppress the loss, it is ideal that the water flowing into the impeller flows linearly in the axial direction (the direction in which the pump shaft extends). On the other hand, one of the causes of loss is the separation of water in the intermediate casing having guide vanes. In order to suppress this separation, it is desirable to avoid an extreme change in the direction of water flow. In the multistage submersible pump, the flow to which the swirl component is imparted by the first stage impeller flows into the second and subsequent intermediate casings. Changing the inflowing water having the swirl component into a linear flow in order to approach the ideal state described above is accompanied by an extreme change in the water flow direction, and as a result, separation is likely to occur. In other words, there is a trade-off relationship between controlling the loss by making the flow of water flowing into the impeller a linear flow in the axial direction and suppressing the loss while avoiding an extreme change in the water flow direction. is there.

In recent years, multi-stage submersible pumps in which the flow direction of water flowing into the first-stage intermediate casing has a swirling component while the flow direction of water flowing into the second-stage and subsequent stages has a swirling component have been recently developed. Considering that the flow of water having a swirl component is dominant, the impeller of the multistage submersible pump is designed so that the impeller can exhibit the best performance in the inflow flow having a predetermined swirl component. May be designed. The impeller designed in this way is also referred to as a swivel design impeller. In a multistage submersible pump provided with a swirl design impeller, good efficiency can be ensured to some extent as a whole pump.

However, in the swirl design impeller, the flow direction of the water flowing into the first stage is a linear flow different from the optimum design condition, so the performance of the first stage impeller is the same as that of the second and subsequent impellers. It will be inferior to performance. For this reason, the multistage submersible pump provided with the turning design impeller leaves room for improvement in terms of efficiency.

One way to improve the efficiency of a multistage submersible pump with a swirl design impeller is to install the first impeller so that the best performance can be achieved against a straight flow that does not have a swirl component. It is conceivable to design separately from the second and subsequent impellers. However, in this case, impellers having the same shape cannot be used for each stage, and the types of parts increase. As a result, the manufacturing man-hours increase, the cost increases, and the maintainability deteriorates.

As another method for improving the efficiency of a multistage submersible pump equipped with a swirl design impeller, it is conceivable to improve the suction casing so that the flow direction of water flowing into the first stage includes a swirl component. For example, Patent Documents 2 and 3 are known as techniques for imparting a swirl component to the inflow water to the pump. In Patent Documents 2 and 3, a swirl component (also referred to as pre-swirling) is imparted to the inflowing water by providing an arc-shaped rectifying plate (water guide plate) in the suction flow path. However, adding such a rectifying plate causes complication of the apparatus, cost increase, and complicated maintenance.

For this reason, in multistage submersible pumps, there is a need for a technique that causes a pre-swirl in the inflow water to the pump without adding a special member.

The present invention has been made to solve at least a part of the above-described problems, and can be realized, for example, as the following modes.

According to the first aspect of the present invention, a suction casing for a multistage submersible pump that handles liquid is provided. The suction casing includes a plurality of casing bodies that extend along the axis and are arranged at intervals in the circumferential direction around the axis. A plurality of suction ports are formed along the circumferential direction by gaps between the plurality of casing bodies. In the cross-section orthogonal to the axis, the plurality of suction ports are in a direction in which the liquid inflow direction in each of the plurality of suction ports is different from the direction toward the axis, and the liquid inflow direction in each of the plurality of suction ports is a plurality of The inflow direction of the liquid at one of the suction ports is formed to be a direction rotated by a predetermined angle about the axis.

According to such a suction casing, the liquid flowing in from the plurality of suction ports can form a swirling flow. That is, it is possible to cause a pre-turn in the liquid flowing into the first stage of the multistage submersible pump. Moreover, it is not necessary to add a member such as a current plate for that purpose.

According to the second embodiment of the present invention, a suction casing for a multistage submersible pump that handles liquid is provided. The suction casing includes a plurality of casing bodies that extend along the axis and are arranged at intervals in the circumferential direction around the axis. A plurality of suction ports are formed along the circumferential direction by gaps between the plurality of casing bodies. The plurality of suction ports are formed so that the liquid flowing in from the plurality of suction ports flows in a direction different from the direction toward the axis in a cross section orthogonal to the axis to generate a swirling flow. According to this suction casing, the same effects as those of the first embodiment are produced.

According to the third aspect of the present invention, in the first or second aspect, the plurality of suction ports are configured such that the inflow direction of the liquid in each of the plurality of suction ports is rotationally symmetric about the axis. It is formed. According to this form, a more uniform pre-turn can be generated.

According to the fourth aspect of the present invention, in any one of the first to third aspects, the suction casing further includes a plurality of casing bodies in the circumferential direction at one end or both ends of the plurality of casing bodies in the axial direction. The flange part connected to is provided. According to this mode, the suction casing can be easily connected to the intermediate casing and the motor by using the flange portion, so that the assembly of the multistage submersible pump is facilitated.

According to the fifth aspect of the present invention, a multistage submersible pump that handles liquid is provided. The multistage submersible pump includes a suction casing according to any one of the first to fourth aspects, a motor disposed on one side of the suction casing in the axial direction, and an intermediate casing disposed in multiple stages on the other side of the suction casing. And the intermediate casing in which the impeller rotated by the motor is accommodated in each stage is provided. According to such a multistage submersible pump, the same effects as in any of the first to fourth embodiments can be obtained.

It is sectional drawing which shows schematic structure of the multistage submersible pump as one Embodiment of this invention. It is a perspective view of a suction casing. FIG. 2 is a cross-sectional view of the suction casing along the line AA in FIG. 1. It is sectional drawing corresponding to FIG. 3 of the suction casing as a comparative example.

A. Example:
FIG. 1 is a cross-sectional view showing a schematic configuration of a multistage submersible pump 20 as an embodiment of the present invention. In the present embodiment, the multistage submersible pump 20 (hereinafter also simply referred to as pump 20) is a submersible pump for deep wells that is installed so that the whole is submerged in the well water. However, the use of the pump 20 is not limited, and the pump 20 can be any multistage submersible pump that handles liquid. Further, the number of stages can be any number of 2 or more.

As shown in the figure, the pump 20 includes a motor 30, a shaft 40, a suction casing 100, and

intermediate casings

50, 60, and 70 connected in multiple stages. The shaft 40 extends in the longitudinal direction inside the pump 20 and has an axis AL. The shaft 40 is connected to the motor 30 via a coupling 41.

The suction casing 100 is arranged coaxially with the axis AL. The suction casing 100 includes a suction casing main body 110 and

flange portions

120 and 130. The suction casing 100 is formed with a suction port 111 (in this embodiment, four suction ports 111a to 111d are formed as will be described later, but here they are collectively referred to as the suction port 111). Yes. One end side of the suction casing 100 in the axis line AL direction is fixed to the motor 30 by a bolt 125, and the other end side is fixed to the intermediate casing 50 by a bolt 135.

The

intermediate casings

50, 60, and 70 are connected in multiple stages in this order along the axis AL as viewed from the motor 30 side.

Impellers

51, 61, and 71 are accommodated in the

intermediate casings

50, 60, and 70, respectively. The

impellers

51, 61 and 71 are fixed around the shaft 40. In addition,

guide vanes

52, 62, and 72 are provided inside the

intermediate casings

50, 60, and 70 following the

impellers

51, 61, and 71, respectively.

In such a pump 20, when the motor 30 is driven, the shaft 40 rotates together with the

impellers

51, 61, 71. Thereby, as shown to arrow A1, water flows in into the suction casing 100 from the suction inlet 111, and flows toward the intermediate casing 50 side along the axis line AL. Then, the water flowing into the first stage intermediate casing 50 is sent to the guide vane 52 by the impeller 51, pressurized by the guide vane 52, and flows into the second stage intermediate casing 60. Similarly, the water flowing into the second-stage intermediate casing 60 is sent to the guide vane 62 by the impeller 61, is pressurized by the guide vane 62, and flows into the third-stage intermediate casing 70. In this way, the water flowing in from the suction port 111 is sent to the subsequent stage while being sequentially boosted in each stage, and the discharge casing (not illustrated) connected to the subsequent stage of the intermediate casing (not illustrated) in the final stage. Discharged from.

FIG. 2 is a perspective view of the suction casing 100. FIG. 3 is a cross-sectional view of the suction casing 100 along the line AA of FIG. 1 orthogonal to the axis AL. As shown in FIG. 3, the suction casing 100 includes four suction casing bodies 110a to 110d in this embodiment. These suction casing bodies 110a to 110d extend along the axis AL as shown in FIG. Further, as shown in FIG. 3, the suction casing bodies 110a to 110d are arranged at intervals in the circumferential direction around the axis AL. In the present embodiment, the suction casing bodies 110a to 110d have the same shape, and the cross-sectional shape is formed in an L shape. However, the shapes of the suction casing bodies 110a to 110d can be arbitrarily set. In the present embodiment, the suction casing bodies 110a to 110d are arranged so as to be rotationally symmetric about the axis AL.

As shown in FIG. 3, four suction ports 111a to 111d are formed along the circumferential direction by a gap between adjacent suction casing bodies among these suction casing bodies 110a to 110d. In this embodiment, the suction casing bodies 110a to 110d having the same shape are arranged so as to be rotationally symmetric about the axis AL, so that the suction ports 111a to 111d are also rotationally symmetric about the axis AL. Are arranged as follows.

As shown in FIG. 3, the suction ports 111a to 111d are formed so that the water inflow directions A2 to A5 in the suction ports 111a to 111d are different from the direction toward the axis AL. Since the suction ports 111a to 111d are arranged so as to be rotationally symmetric about the axis AL, the water inflow directions A2 to A5 are also rotationally symmetric about the axis AL (90 degrees in this embodiment). Rotational symmetry).

According to the inflow directions A2 to A5 of the suction ports 111a to 111d, as shown in FIG. 3, the swirling flow indicated by the arrow A6 can be generated by the water flowing from the suction ports 111a to 111d. That is, the water flowing in from the suction ports 111a to 111d flows along the axis AL while turning around the axis AL, and flows into the first-stage intermediate casing 50. For this reason, pre-swirl can be caused in the water flowing into the first-stage intermediate casing 50 without adding a member such as a current plate. As a result, in all stages including the first stage, the flowing water can be swirled. Therefore, the efficiency of a multistage submersible pump provided with a turning design impeller can be improved. In addition, in the present embodiment, the suction ports 111a to 111d are formed so that the inflow directions A2 to A5 are rotationally symmetric about the axis AL, so that a more uniform pre-turn can be generated. .

However, the inflow directions A2 to A5 can be arbitrarily set such that the inflow direction of water at one of the suction ports 111a to 111d is rotated by a predetermined angle about the axis AL. . That is, the inflow direction of each suction port can be arbitrarily set so that the flow direction of water flowing from the suction port does not cancel the swirl flow. Further, the number of suction ports is not limited to four and can be any number of two or more. In other words, the number of suction casing bodies can be any number of three or more. Furthermore, the inner surface of the suction casing body (the inner surface forming the flow path) can be of any shape, for example, an arc shape (for example, the axis AL) in order to suppress sudden changes in the direction of water flow as much as possible. May be formed in a shape of a part of a circle centered at.

Further, as shown in FIG. 2, the suction casing 100 includes

flange portions

120 and 130. The

flange portions

120 and 130 are formed at both ends of the suction casing bodies 110a to 110d in the direction of the axis AL, and connect the suction casing bodies 110a to 110d in the circumferential direction. The flange 120 is formed at the end of the suction casing bodies 110a to 110d on the motor 30 side. A plurality of bolt holes 121 are formed in the flange portion 120 in the circumferential direction. Using the bolt hole 121, the motor 30 and the suction casing 100 can be fixed by the bolt 125 as described above.

The flange portion 130 is formed at the end of the suction casing bodies 110a to 110d on the intermediate casing 50 side. The flange portion 130 includes a first large-diameter portion 131 adjacent to the suction casing bodies 110a to 110d, a second large-diameter portion 133 adjacent to the intermediate casing 50, the first large-diameter portion 131, and the second large-diameter portion. A small-diameter portion 132 between the small-diameter portion 133. A plurality of bolt holes 134 are formed in the second large diameter portion 133 in the circumferential direction. The bolt hole 134 is formed radially outside the outer peripheral surface of the small diameter portion 132. Using the bolt hole 134, the suction casing 100 and the intermediate casing 50 can be fixed by the bolt 135 as described above. Further, since the small diameter portion 132 is formed, the insertion of the bolting tool and the movable region are ensured satisfactorily. Therefore, the suction casing bodies 110a to 110d are formed on the plane orthogonal to the axis AL. The bolt 135 can be easily tightened.

Further, as shown in FIG. 3,

notches

122 and 123 are formed in the flange portion 120. These

notches

122 and 123 can be used as accommodation spaces for power cables connected to the motor 30.

FIG. 4 is a cross-sectional view corresponding to FIG. 3 of a suction casing 200 as a comparative example. As illustrated, the suction casing 200 includes four substantially U-shaped suction casing bodies 210a to 210d, and suction ports 211a to 211d are formed by gaps therebetween. The inflow directions A7 to A10 of water at the suction ports 211a to 211d are directions toward the axis AL. In such a suction casing 200, the swirling flow as shown by the arrow A6 in FIG. 3 does not occur, and the water flowing in from the suction ports 211a to 211d goes straight to the intermediate casing 50 along the axis AL. . Therefore, when the suction casing 200 is used for a multistage submersible pump including a swirl design impeller, the efficiency at the first stage is reduced as compared with the case where the suction casing 100 of the present embodiment is used.

Although several embodiments of the present invention have been described above, the above-described embodiments of the present invention are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents thereof. Moreover, in the range which can solve at least one part of the subject mentioned above, or the range which exhibits at least one part of an effect, the combination of each component described in the claim and the specification, or omission is possible. .

DESCRIPTION OF SYMBOLS 20 ... Multistage submersible pump 30 ... Motor 40 ... Shaft 41 ...

Coupling

50, 60, 70 ...

Intermediate casing

51, 61, 71 ...

Impeller

52, 62, 72 ... Guide vane 100 ...

Suction casing

110, 110a, 110b, 110c , 110d ...

Suction casing body

111, 111a, 111b, 111c, 111d ...

Suction port

120, 130 ...

Flange part

121, 134 ...

Bolt hole

122, 123 ...

Notch

125, 135 ... Bolt 131 ... First large diameter part 132 ... Small diameter part 133 ... Second large diameter part AL ... Axis

Claims

A suction casing for a multistage submersible pump that handles liquid,
A plurality of casing bodies that extend along the axis and are arranged at intervals in the circumferential direction around the axis;
A plurality of suction ports are formed along the circumferential direction by the gaps between the plurality of casing bodies,
In the cross section orthogonal to the axis, the plurality of suction ports,
The inflow direction of the liquid in each of the plurality of suction ports is different from the direction toward the axis,
The inflow direction of the liquid in each of the plurality of suction ports is a direction obtained by rotating the inflow direction of the liquid in one of the plurality of suction ports by a predetermined angle about the axis. Formed suction casing.
A suction casing for a multistage submersible pump that handles liquid,
A plurality of casing bodies that extend along the axis and are arranged at intervals in the circumferential direction around the axis;
A plurality of suction ports are formed along the circumferential direction by the gaps between the plurality of casing bodies,
The plurality of suction ports are formed so that the liquid flowing in from the plurality of suction ports flows in a direction different from the direction toward the axis in a cross section orthogonal to the axis to generate a swirling flow. Suction casing.
The suction casing according to claim 1 or 2, wherein
The suction casing is formed such that an inflow direction of the liquid in each of the plurality of suction ports is rotationally symmetric about the axis.
A suction casing according to any one of claims 1 to 3,
Furthermore, the suction casing is provided with a flange portion that connects the plurality of casing bodies in the circumferential direction at one end or both ends of the plurality of casing bodies in the axial direction.
A multistage submersible pump that handles liquids,
A suction casing according to any one of claims 1 to 4,
A motor disposed on one side of the suction casing in the axial direction;
A multi-stage submersible pump, comprising: an intermediate casing arranged in multiple stages on the other side of the suction casing, wherein the intermediate casing accommodates in each stage an impeller that is rotationally driven by the motor.