JP2000303997A - Water supply device of centrifugal pump with double scroll chamber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the vibration of a pump by connecting the discharge passages of the respective scroll chambers of a centrifugal pump with a double scroll chamber by a connecting passage, and setting the sectional area of the passage of the communicating passage in a range of specified proportion to the smaller passage sectional area of the discharge passage. SOLUTION: A suction opening of a centrifugal pump 1 with a double scroll chamber is connected to a water source such as a river or the like through a suction passage, and two discharge openings 5A, 5B of the pump 1 are connected to a conflux passage through discharge passages 6A, 6B to be guided to a water using place. Such intake pump 1 is large-sized and the discharge passages 6A, 6B are formed by a concrete pipe to keep the strength. In this case, the discharge passages 6A, 6B are connected to each other by a communicating passage 11. The passage sectional area of the communicating passage 11 is set from 50% to 100% both inclusive of the smaller discharge passage 6A or 6B. The distance L of the communicating passage 11 from a tongue part 18B of the scroll chamber 17B of the pump 1 is set from two times to five times both inclusive as large as the diameter D of a pump impeller 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for feeding water from a river, for example, in which a suction port of a centrifugal pump with a double spiral chamber is connected to a water source through a suction channel, and a centrifugal pump with a double spiral chamber is used. The present invention relates to a water supply device in which a discharge port of each spiral chamber of a pump is connected to a water use place via a discharge channel.

[0002]

2. Description of the Related Art In a device for feeding river water, a centrifugal pump is often used as a large-sized and high-yield pump. This centrifugal pump has a pump impeller with a diameter of 1
M or more, and a vertical type with a double spiral chamber is used to reduce the radial thrust load accompanying rotation of the pump impeller. The vertical rotation of the pump impeller eliminates the radial thrust load due to gravity.However, when the flow rate at each discharge port changes, the hydraulic pressure balance between the two spiral chambers is lost, and the radius associated with the rotation is reduced. Thrust load increases and negatively affects pump performance,
It may cause vibration and the rotating shaft may be damaged by fatigue.

Here, in the case of a large-sized centrifugal pump, the discharge channel is often formed of a concrete structure, but in this case, the width of the water channel cannot be made too large from the viewpoint of strength. Further, since a management building is usually provided upright around the pump device, it is not preferable in view of strength if the width of the flow path is widened. Therefore, conventionally, the two discharge flow paths are separately formed.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to minimize the imbalance in the hydraulic pressure between the two swirl chambers due to a change in the flow rate on the discharge port side in two discharge channels, It is an object of the present invention to provide a centrifugal pump water supply device with a double vortex chamber, which can suppress an increase in radial thrust load and eliminate vibration of the pump and maintain suitable pump performance for a long period of time.

[0005]

According to the present invention, the suction port of the centrifugal pump with a double spiral chamber is connected to a water source via a suction flow path, and the discharge of each spiral chamber of the centrifugal pump with a double spiral chamber is performed. In a water supply device of a centrifugal pump with a double vortex chamber, each outlet of which is connected to a water use site through a discharge channel,
The two discharge flow paths are connected by a communication path, and the flow path cross-sectional area of the communication path is 50 times the smaller flow path cross-sectional area of the discharge flow path.
% And within 100%.

According to the present invention, the distance between the communication passage and the tongue of the centrifugal pump of the double centrifugal chamber is at least twice the diameter of the impeller of the centrifugal pump with double centrifugal chamber. It is within 5 times.

[0007] Since the discharge passages are connected by the communication passages as described above, the collapse of the hydraulic pressure balance between the two swirl chambers due to the change in the flow rate at each discharge port side is minimized by the communication passages.
The increase in the radial thrust load of the rotating shaft is suppressed, the vibration of the pump is eliminated, and the suitable pump performance can be maintained for a long time.

The cross-sectional area of the communication passage is 50% or more and 100% or more of the smaller cross-sectional area of the discharge passage.
Therefore, it is possible to prevent a change in the liquid pressure in both the spiral chambers due to the flow rate of each discharge channel. In addition, the effect of reducing the radial thrust is increased, and the pipe resistance in the flow path,
Channel loss is reduced. On the other hand, there is no problem in strength as a structure.

The distance between the communication path and the tongue of the centrifugal pump of the centrifugal pump with a double centrifugal chamber is at least twice and not more than 5 times the diameter of the impeller of the centrifugal pump with a double centrifugal chamber. Therefore, it is possible to quickly equalize the liquid pressure in both the spiral chambers without impairing the function as the spiral chamber. Here, since the distance between the communication path and the tongue of the centrifugal pump of the centrifugal pump with a double volute is at least twice the diameter of the impeller of the centrifugal pump with a double volute, the pressure recovery of the fluid is sufficient. , And the performance does not decrease. In addition, the distance between the communication passage and the tongue of the centrifugal pump of the double centrifugal pump is less than 5 times the diameter of the impeller of the centrifugal pump with double centrifugal chamber. Therefore, it becomes easy to cope with the difficulty of securing the land.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, a suction port 2 of a centrifugal pump with a double swirl chamber (hereinafter referred to as a pump 1) generally denoted by reference numeral 1 is connected to a water source 4 such as a river via a suction flow path 3. The two discharge ports 5A and 5B are connected to a junction 7 via discharge paths 6A and 6B, and are led to a water use place 8. Then, each discharge channel 6A,
6B is a gate valve 9A, 9B, a check valve or a flap valve 1.
0A, 10B, etc. are provided. Such a water intake pump 1 is large in size, and the discharge channels 6A and 6B are formed of concrete pipes to maintain strength, and are connected to a junction 7 near a water use place 8. Then, the discharge channel 6A,
6B is connected by the communication path 11 mentioned later.

As shown in FIGS. 2 and 3, a suction stationary vane 12 is provided at a suction port 2 of the pump 1 connected to the suction passage 3, and the pump vanes are opposed to the suction stationary vane 12. Car 13
Is provided. The rotating shaft 14 of the pump impeller 13
Are held by bearings 15 and driven by a driving machine (often an engine) 16.

Around the pump impeller 13, two spiral chambers 17A and 17B are provided, and the first spiral chamber 17A is connected to the first discharge channel 6A through the first discharge port 5A. The second spiral chamber 17B is connected to the second discharge channel 6B via the second discharge port 5B.

The first discharge passage 6A and the second discharge passage 6B are connected by a communication passage 11. The flow path cross-sectional area of the communication path 11 is smaller than the smaller discharge flow path 6A or 6A.
B is 50% or more and 100% or less. Here, the discharge channel 6A or 6B having the smaller cross-sectional area of the communication channel 11 is used.
The reason why the radial thrust reduction effect is small when the ratio is less than 50% is less than 50%.
This is because the radial thrust becomes larger than the characteristic shown by the curve X (described later) as shown by. If it is less than 50%, when a valve fails, the pipe resistance of the flow path becomes large, and it becomes impossible to secure a necessary amount of water. 50% more
If it is less than 5, the flow path loss becomes large at the time of valve failure, and the pump performance (especially efficiency) is significantly reduced. On the other hand, if the flow passage cross-sectional area of the communication passage 11 is set to 100% or more of the smaller discharge flow passage 6A or 6B, there is a problem in strength as a structure. Further, by setting the cross-sectional area of the flow path to 50% or more, the hydraulic pressures of the two spiral chambers 17A and 17B can be quickly equalized through the respective discharge flow paths 6A or 6B. In addition to this, since it is 100% or less,
The discharge passages 6A and 6B can be easily connected by the communication passage 11.

The distance L of the communication passage 11 from the tongue portion 18B is provided at a position of not less than twice and not more than 5 times the diameter D of the pump impeller 13. Here, in the double centrifugal pump, the pressure of the fluid is recovered by the centrifugal chamber to ensure the performance. However, the communication path 11 is installed at a position where the distance from the tongue 18B is twice or less the diameter D of the pump impeller 13. If you do
Fluid pressure recovery is not sufficient and performance is degraded. On the other hand, in recent water transmission devices, downsizing is required in view of the difficulty of securing land.
If the distance L from B to the communication path 11 is too large, it will be difficult to make it compact. Therefore, the distance L from the tongue 18B to the communication passage 11 is 5 times the diameter D of the pump impeller 13.
I try not to double it. In addition, since the communication passage 11 is provided at a position at least twice the diameter D of the pump impeller 13, the function as the spiral chamber 17A is not impaired. And since it is provided in the position of 5 times or less, the hydraulic pressure of both the spiral chambers 17A and 17B can be quickly equalized.

Next, the operation of the water supply device of the present invention will be described with reference to the drawings. When the impeller 13 is driven by the driving device 16,
The water in the suction passage 3 connected to the water source 4 flows through the suction port 2 and the suction stationary vane 12. Then, the water accelerated by the impeller 13 flows out of the discharge ports 5A and 5B through the spiral chambers 17A and 17B. Outlet 5A,
The water flowing out of 5B flows to the water use place 8 through the discharge flow paths 6A and 6B.

In such a water supply device, for example, a gate valve 9A or 9B, a check valve or a flap valve 10A,
When B is closed or malfunctions due to malfunction, the flow rate of the discharge flow path 6A or 6B changes. Then, the water of the discharge flow path 6A or 6B whose flow rate has decreased flows through the communication path 11 to the other discharge flow path 6A or 6B, and the swirl chamber 1
The pressure balance between 7A and 17B is not lost.

However, since the conventional water supply device does not have the communication path 11, when the flow rate of the discharge flow path 6A or 6B changes,
The pressure balance between the two spiral chambers 17A and 17B is lost, and a so-called radial thrust load in a direction perpendicular to the bearing 15 of the rotating shaft 14 is generated. Then, the water supply performance of the pump deteriorates, causing vibration, and the rotating shaft 14 may be fatigued and damaged.

FIG. 4 shows the discharge flow rate of the pump on the horizontal axis and the radial thrust load of the bearing on the vertical axis, and shows the discharge flow rate at the highest efficiency point of the pump having two discharge flow paths at 100.
%, And the radial thrust load at that point is 100%. Here, the curve W is a characteristic curve when the flow passage cross-sectional area of the communication passage 11 is 25% of the smaller discharge flow passage 6A or 6B. A curve X is a characteristic curve in a case where the conventional water supply device without a communication passage is operated in two flow paths. Curve Y is a characteristic curve when the conventional water supply device without a communication passage is operated with one gate valve closed. Curve Z is a water supply device of the present invention provided with a communication passage,
It is a characteristic curve at the time of driving | operation with one gate valve closed.

In the water supply device in which this experiment was conducted, the cross-sectional areas of the two discharge passages 6A and 6B were the same, and the cross-sectional area of the communication passage 11 was 50% of the discharge passage 6A. And
The communication passage 11 is provided at a position away from the tongue 18B by a distance 4D (D is the diameter of the pump impeller 13).

As shown in FIG. 4, the flow passage cross-sectional area of the communication passage 11 is within a predetermined range (the smaller of the smaller discharge passages 6A or 6B).
When it is out of the range of 0% or more and 100% or less (for example, 25%), the radial thrust load is relatively large. In addition, in the conventional water supply device having no communication passage, when water is supplied only through one of the discharge passages, the radial thrust load extremely increases as shown by a curve Y. On the other hand, as shown by the curve Z, in the water supply device of the present invention provided with the communication passage, the radial thrust load does not increase.
In addition, in the conventional water supply device having no communication passage, the radial thrust load is smaller than that in the case where water is supplied through both discharge flow paths (curve X), and suitable water supply performance can be maintained for a long time.

It should be noted that the illustrated embodiment is merely an example, and is not intended to limit the technical scope of the present invention.

[0022]

According to the present invention described above, the suction port of the centrifugal pump with a double spiral chamber is connected to a water source through a suction channel, and the discharge of each spiral chamber of the centrifugal pump with a double spiral chamber is performed. In the water supply device in which the outlet is connected to the water use place through the discharge channel, since the discharge channel is connected by the communication path,
The communication passage minimizes the collapse of the hydraulic pressure balance between the two swirl chambers due to the change in the flow rate at each discharge port side, suppresses the increase in the radial thrust load of the rotating shaft, eliminates pump vibration, and improves pump performance. Can be kept for a long time.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a water supply device of the present invention.

FIG. 2 is a vertical sectional view of a centrifugal pump with a double vortex chamber of the water supply device of the present invention.

FIG. 3 is a cross-sectional view of a centrifugal pump with a double swirl chamber of the water supply device of the present invention.

FIG. 4 is a diagram showing a relationship between a discharge flow rate of a pump and a radial thrust load of a rotating shaft of an impeller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Centrifugal pump with double vortex chamber 2 ... Suction port 3 ... Suction channel 4 ... Water source 5A, 5B ... Discharge port 6A, 6B ... Discharge channel 8. ..Water use area 9A, 9B ... gate valve 10A, 10B ... check valve or flap valve 11 ... communication path 12 ... suction stationary vane 13 ... pump impeller 14 ...・ Rotating shaft 15 ・ ・ ・ Bearing 16 ・ ・ ・ Driver 17A, 17B ・ ・ ・ Swirl chamber 18A, 18B ・ ・ ・ Tongue

Claims (2)

[Claims] 1. A suction port of a centrifugal pump with a double spiral chamber is connected to a water source through a suction channel, and a discharge port of each of the spiral chambers of the centrifugal pump with a double spiral chamber is discharged through a discharge channel. In the water supply device for a centrifugal pump with a double convoluted chamber connected to a water use site, the two discharge channels are connected by a communication channel, and the cross-sectional area of the communication channel is smaller than that of the discharge channel. A water supply device for a centrifugal pump with a double vortex chamber, characterized in that the flow path cross-sectional area is 50% or more and 100% or less. 2. The distance between the communication passage and the tongue of the spiral chamber of the centrifugal pump with a double spiral chamber is at least twice and within five times the diameter of the impeller of the centrifugal pump with a double spiral chamber. The water supply device according to claim 1.