JPH0454300A - Upright shaft pump - Google Patents

Abstract

PURPOSE:To conduct a water raising operation even at a water level that is lower than the lowest water level without generating a harmful whirl, by taking a means in which the blade wheel of a pump is positioned at a lower part than the lowest water level at which air is sucked through a sucking-in bell if a water level during a pump operation becomes lower, or the like. CONSTITUTION:The static pressure of an ejection hole 16 becomes always higher than that of an air suction hole 9 during a pump operation, and the quantity of air suction through the hole 9 is controlled by regulating the openings of a flow regulating valve 13 and an air intake quantity regulating valve 11. That is, in case of a water level being more than the prior lowest water level, even if the air intake quantity regulating valve 11 is opened, no air suction is made through the hole 9 as the static pressure of the hole 9 is higher than that of an intake opening 12, but static pressure balance between the hole 9 and the intake opening 12 is reversed by opening the flow regulating valve 13, and a flow control is conducted by conducting air suction of an appropriate quantity. Meanwhile, in case of a water level being less than the conventional lowest water level, as the static pressure of the hole 9 is lower than that of the intake opening 12, a flow control is conducted by closing the flow regulating valve 13 and regulating the opening of the air intake quantity regulating valve 11 and conducting air intake of an appropriate quantity to carry out flow control.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a seawater pump for cooling auxiliary equipment in a coastal power plant, and is designed to prevent large fluctuations in the water level in the water intake tank due to the effects of building waves during an earthquake. This invention relates to a vertical shaft pump that is capable of stably and continuously pumping water.

[Conventional technology]

In conventional devices, as described in Japanese Patent Application No. 63-228736, when the water level when the pump is submerged exceeds the minimum water level below which air will be sucked in, flow rate control is not performed and the predetermined flow rate is maintained. There are vertical shaft pumps that maximize pumping capacity, control the pump flow rate below the minimum water level, and enable operation without generating harmful vortices.

[Problem to be solved by the invention]

Normally, in order to control the flow rate of a seawater pump for cooling auxiliary equipment in a coastal power plant, there are methods such as adjusting the opening degree of the discharge valve or adjusting the rotation speed of the pump shaft.

However, in the prior art, when the opening degree of the discharge valve is reduced, the head loss increases, and the driving power of the pump increases. Furthermore, when adjusting the rotation speed of the pump shaft, equipment for adjusting the rotation speed is required. In addition, both types cannot perform pumping operation at a water level lower than the minimum water level, for example, at a water level lower than the known minimum water level, which is 1.4 to 1.7 times the diameter of the suction bell from the suction port.

The purpose of the invention is to control the flow rate of the pump at all water levels, even at water levels below the minimum water level, without creating harmful vortices.
The objective is to obtain a vertical shaft pump that enables pumping operation.

[Means to solve the problem]

In order to achieve the above object, the present invention is designed to prevent air from being sucked in through the suction bell when the water level is lower than that during pump operation.
The impeller of the pump is located below the position corresponding to the lowest water level, and an intake hole is provided in the pump casing below this impeller, and a discharge hole is provided in the discharge elbow or discharge piping located above, and this discharge A water pipe connects the hole and the intake hole and has an ejector installed in the middle, and an intake pipe has one end connected to the ejector and the other end open to the atmosphere.

[Effect]

Even if there are large fluctuations in the water level in the water intake tank due to the effects of tsunamis during earthquakes, etc., the water level is kept at or above the conventional minimum water level so that seawater for cooling power plant auxiliary equipment can be continuously and stably pumped. Now, the discharge side pressure of the white liquor is used to adjust the amount of intake air from the intake hole and control the pumping flow rate. On this occasion,
By increasing the amount of intake air, it is possible to reduce the water pumping flow rate without changing the required power of the pump.

In addition, if the water level is below the conventional minimum water level, as the water level falls, the pump flow rate will decrease accordingly, preventing air entrainment from the suction bell and causing abnormal vibrations and noises that are harmful to pump operation. can be prevented.

In addition, since the pumping flow rate is reduced from the period when the water level in the water intake tank is high, the flow velocity on the upstream side of the water intake tank can be slowed down, and it is possible to prevent unintentional excessive water level drops due to low water levels such as tsunamis.
Enables stable pump operation.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, the suction bell 3 of the pump casing 4 is connected to the lower side of the pump casing 40 housing the impeller 1 and the casing liner 2, and the pumping pipe 5 that is a part of the pump casing 4 is connected to the upper side. ．． A discharge elbow 6 is connected to constitute a vertical shaft pump. Discharge elbow 6
A discharge pipe 7 and a discharge valve 8 are provided on the discharge side. Further, an intake hole 9 is provided near the bottom of the impeller 1, and is connected to a discharge hole 16 of the discharge pipe 7 through a water conduit 15. A flow rate regulating valve 13 and an ejector 14 are installed in the water conduit 15, and a flow rate control device is provided. It consists of Further, an intake pipe 10 whose one end is open into a water intake tank is connected to the ejector 14, and an intake air amount adjusting valve 11 is installed in the intake pipe 10 to constitute an intake air amount control device.

During pump operation, the static pressure in the discharge hole 16 is always higher than the static pressure in the intake hole 9, and by adjusting the opening degree of the flow rate adjustment valve 13 and the opening degree of the intake air amount adjustment valve 11, the amount of water from the intake hole is reduced. The amount of intake air is controlled. In other words, when the water level is higher than the conventional minimum water level, even if the intake air amount adjustment valve 11 is opened, the static pressure at the intake hole 9 is higher than the static pressure at the intake port 12, so air is not taken in from the intake hole 9, but the flow rate is adjusted. By opening the valve 13,
The static pressure balance between the intake hole 9 and the intake port 12 is reversed, and a mixture of white liquid and air is sent from the intake hole 9 into the pump casing 4, and as the water level and discharge pressure change, an appropriate amount of air is taken in and the flow rate is adjusted. Take control.

When the water level is below the conventional minimum water level, the static pressure at the intake hole 9 is lower than the static pressure at the intake port 12, so the flow rate adjustment valve 13 is closed and the opening degree of the intake air amount adjustment valve 11 is adjusted.
As the water level and discharge pressure change, an appropriate amount of air is taken in to control the flow rate.

〔Effect of the invention〕

According to the present invention, due to the influence of tsunami etc. when an earthquake occurs,
Even if there are large fluctuations in the water level in the water intake tank, stable and continuous water pumping is possible. In other words, when the water level is above the conventional lowest water level level, the pumping flow rate can be reduced without changing the required power of the pump. Furthermore, when the water level is below the conventional lowest water level, air is prevented from being drawn in from the suction bell, and abnormal vibrations and noise that are harmful to pump operation can be prevented.

[Brief explanation of drawings]

FIG. 1 is a side view of an embodiment of the vertical shaft pump of the present invention. 1 Impeller, 2 Casing liner, 3 Suction bell, 4 Pump casing, 5 Lifting pipe, 6 Discharge elbow, 7 Discharge piping, 8 Discharge valve, 9 Intake hole,
10...Intake pipe, 11...Intake amount adjustment valve, 12...Intake port, 13...Flow rate adjustment valve, 14...Ejector, 15...
・Water pipe, 16... Bath hole.

Claims (1)

[Claims] 1. If the water level during pump operation is lower than that, air will be sucked in from the suction bell.The pump impeller is positioned below the position corresponding to the lowest water level, and the pump casing below the impeller has an intake hole. Further, a discharge hole is provided in the discharge elbow or discharge pipe located at the upper part, and the discharge hole and the intake hole are connected to a water conduit pipe with an ejector installed in the middle, and one end is connected to the ejector, A vertical shaft pump characterized by having an intake pipe whose other end is open to the atmosphere.