JPS6350699A - Bearing lubrication water supply device - Google Patents

Abstract

PURPOSE:To appropriately control the pressure of lubrication oil, by introducing discharged pressure water into a compensating tank in accordance with variations in the pressure of discharged water so that the differential pressure between the pressure of lubrication water from an accumulator tank and the back pressure of a turbine is held to be constant. CONSTITUTION:Lubrication water from an accumulator tank 17 flows through a protective pipe 12 and a guide vane boss, and is returned into the tank. When the back pressure of an impeller is changed due to variations during operation of a pump, discharged pressure water in a bent pipe 3 is led into a compensating tank 25, and air is fed into the accumulating tank so that lubrication water is pressurized. Accordingly, the pressure of bearing lubrication water may be obtained in accordance with the head of the pump.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention provides a method for adjusting the pressure in a protective tube depending on the back pressure of the pump impeller, which changes due to variations in the pump operating point. This invention relates to a bearing lubricating water supply device that uses pressurized water.

(Conventional example) Conventionally, for example, a bearing lubricating water supply device for a shaft pump has a bearing 71τ1 in a side slide tank a, as shown in FIG.
By operating the circulation pump b, the sliding water is injected into the protection tube d through the water injection pipe C, and this injected sliding water is transferred to an intermediate bearing (not shown) disposed in the axial direction in the protection pipe d. ) and function as a lubricant, it is returned to the lubricating water tank a from inside the guide vane boss via the return pipe Me,
This system recycles bearing lubricating water.

Here, when the V-shaft pump rotates in four directions, the lift of the circulation pump is controlled so that the pumped water does not flow back into the protection tube due to the back pressure Hb of one impeller from the gap between the mechanical seal f at the bottom of the protection tube and the rotating shaft g. In order to make the back pressure Hb of this impeller
is set based on a predetermined standard.

(Problem to be solved by the invention) However, as shown in Fig. 3, the back pressure Hb of the impeller in a shaft pump varies in proportion to the total head of the pump, while the water pressure at the shaft bearing is It is set by the pump and is constant. And, even if we look at the vertical shaft pump at least within the pump operating range, the back pressure Hb of the impeller ip and the bearing 1'1f
There is a problem in that the difference between the ice sliding pressure H1, that is, the differential pressure ΔH=H1−Hb at the mechanical seal portion fluctuates over a wide range, and the blood pressure and leakage (leakage of bearing lubricating water) at the sealing surface are not constant.

Moreover, the differential pressure ΔH increases in proportion to the pump stoichiometry, and as it approaches the large flow 41 side, the sliding surface pressure on the sealing surface increases, especially when the mechanical seal is a pressure ann/hella 7 type. There is a problem that causes grilling.

Also, bearings? IP! Depending on the set value of the sliding pressure, if the pump operating point changes significantly, the difference ΔH = H1 - Hb <.

There is also a risk that the pump solution will flow back into the protective tube from the mechanical seal.

Therefore, in the conventional device, there is a problem in that the flea life and sealing performance of the mechanical seal are adversely affected by the problem described in (h) above.

Furthermore, since the head of the circulation pump is set based on the back pressure Hb of one impeller, the head pressure tends to be set high, which poses a problem of high running costs.

Unreleased II was created with a focus on the Book of L and Bajo.

The purpose of this invention is to provide a bearing lubricating water supply device that can change the bearing lubricating water pressure in response to changes in the pump operating point.

(Structure of the Invention) In order to achieve the above-mentioned object [1], the bearing lubricating water supply device of the present invention includes an accumulator tank to which lubricating water is replenished from a make-up water source, and a pump rotating shaft for supplying lubricating water in the accumulator tank. A water injection pipe that supplies water to a part of the enclosing protection pipe, a guide vane boss that receives lubricating water in the protection pipe, a mechanical seal that seals the lubricating water in the boss with pumped liquid, and a lubrication pipe in the guide vane boss. A return piping that returns water to the accumulator tank, a closed compensation tank that introduces the discharge pressure water in the discharge pipe of the pump via the compensation piping, and air in the compensation tank according to the amount of the discharge pressure water introduced. 7-1 - A communication pipe equipped with a reverse ratio valve for supplying water into the neemulator tank and varying the pressure inside the accumulator tank.

(Function) With this configuration, if the pump operating point changes,
The discharge pressure of the pump also fluctuates, but in this case, discharge pressure water is introduced into the compensation tank via the compensation piping according to the fluctuation in the discharge pressure, and the pressure air in the compensation tank is increased by the amount introduced. It is supplied into the accumulator tank via a communication pipe. Therefore, the pressure in the accumulator tank is changed by nf according to the fluctuation of the pump operating point,
The pressure of bearing lubricating water supplied from the accumulator tank to the protection pipe and the pump impeller 1! The differential pressure can be maintained approximately constant.

(Embodiment) Hereinafter, an embodiment of the present invention will be described based on the drawings of FIGS. 1 to 4A.

In the figure, 1 is a standing sleeve pump, and 2 is a bearing lubricating water supply device provided in this vertical shaft pump 1.

The pipe adjustment structure of the vertical pump 1 consists of a lifting pipe 5 and a pump casing 6 between a part of the bent pipe 3 and a lower bell mouth 4.
It is made by connecting. A rotating shaft 8 connected to a drive E) 7 such as a motor is housed in a pump casing via a packing 9 as shown in FIG. 2, and an impeller 10 is attached to its lower end. A guide vane boss 11 is provided directly above the guide vane boss 11 . In addition, the rotating shaft 8 inside the pump casing is mounted on an intermediate bearing (not shown).
It is mounted on a rotating shaft. Further, the inside of the protective tube 12 is connected to the inside of the kite vane boss through a lower bearing. Furthermore, the pump liquid is sealed by a mechanical seal 14 interposed between the guide vane boss and the boss portion 13 of the impeller 1o.

The bearing lubricating water supply device 2 has an accumulator tank 17, as shown in FIGS. 1 and 2, and I! ! ! A water injection pipe 18 is provided to communicate with the tank 17, a return pipe 19 is provided that communicates with the inside of the guide vane boss, and a screw pump 20 is interposed between the protective pipe 12, the guide vane boss, and the rotary shaft 8. It will be done. Accumulator tank 1
7 can be refilled with water from a replenishment tank 21 which is a replenishment water source through a replenishment pipe 23 with a solenoid valve 22 interposed therebetween. Here, the accumulator tank 17 has a lowest water level LWL.
A level sensor 24 is attached at this position, and when the water level in the tank falls below the lowest water level LWL, the electromagnetic valve 22 is opened in response to detection by the level sensor 24, and lubricating water is refilled from the water replenishment tank 21.

Furthermore, the bearing lubricating water supply device 2 has a sealed compensation tank 25 provided in the accumulator tank 17, and a compensation piping 26 is connected between the lower part of this tank 25 and the inside of the bent pipe 3 of the spindle pump 1. Let's connect.

The pressure water discharged from the bent pipe 3 is introduced into the compensation tank 25. Then, the air in this compensation tank 25 is supplied into the accumulator tank 17 from a communication pipe 28 equipped with a check valve 27 according to the amount of introduction of the discharge pressure tree, so that the pressure in the accumulator tank 17 is varied. ing. Here, the check valve 27 allows air to flow only from the compensation tank 25 to the accumulator tank 17 side. In addition, a drain valve 2 is provided in the compensation tank 25.
9 is provided so that the internal water can be removed after the pump operation is completed.

With this configuration, when the pump rotates normally, the bearing lubricating water in the accumulator tank 17 flows through the water injection pipe 18. It can sequentially flow into the protection tube 12, the screw pump 20, the guide vane boss, and the return pipe 19, and be returned to the accumulator tank 17 again. When the pump operating point is changed and the back pressure Hb of the impeller is about to rise, the discharge pressure water in the bent pipe 3 is transferred to the compensation tank 25.
The air in the compensation tank 25 is supplied into the accumulator tank 17 via the communication pipe 28, and the lubricating water in the tank 17 is pressurized. Therefore, the differential pressure between the pressure of the bearing lubricating water supplied into the protection tube 12 and the back pressure of the impeller is always kept constant. By the way, the relationship between the flow rate Q and the total head H at the operating point of the spindle pump 1 is expressed by the third
A pump lift curve 30 as shown in the figure is obtained, and the back pressure Hb of the impeller also follows the pump lift curve 30 as shown in the figure. The bearing lubricating water pressure H'JI pressurized by the pressure compensator 16 follows the pump lift curve 30 and the impeller back pressure Hb, as shown in the figure.

Therefore, the differential pressure ΔH"1=H' between the bearing lubricating water pressure H'l and the impeller back pressure Hb at the mechanical seal 14 part
1-Hb does not make a large difference at any operating point.

In addition, in the ``biped'' embodiment, a configuration in which the accumulator tank 17 and the compensation tank 25 are integrated has been described, but the present invention is not limited to this, and may be configured as separate units.

(Effects) As described above, according to the bearing lubricating water supply device of the present invention, the bearing lubricating water pressure can be adjusted according to the pump lift, so that the ΔH at the mechanical seal portion can be made approximately constant at any pump operating point. At the same time, the differential pressure ΔH can be
'', the life of the mechanical seal and the sealing performance of the mechanical seal can be improved.

In addition, as in the above embodiment, if the bearing lubricating water is circulated using a screw pump that does not require a power source, there will be no need for a circulation pump or a motor to drive it as in conventional devices, which will significantly reduce running costs. can be done.

[Brief explanation of drawings]

1 to 3 show one embodiment of the present invention, FIG. 1 is an overall configuration diagram, FIG. 2 is a schematic cross-sectional view showing FIG. 1 in more detail, and FIG. 3 is a diagram showing the pump flow rate. A diagram showing the lift height and pressure of each part, and FIG. 4 is an overall configuration diagram showing a conventional device. l... Support shaft pump (pump) 2... Bearing lubricating water supply device 8... Rotating shaft 10... Impeller 11... Guide vane boss 12... Protection tube 14... Mechanical seal 18...Water injection pipe 19...Return pipe 21...Water replenishment tank (replenishment water source) 26...Compensation pipe 27...Check valve 28...Communication pipe Patent applicant Kubota Iron Works Co., Ltd. Agent Man
Patent Attorney Takashi Suzue - Figure 1 Mujikako

Claims (1)

[Claims] an accumulator tank to which lubricating water is replenished from a supply water source; and water injection piping for supplying lubricating water in the accumulator tank to an upper part of a protection pipe surrounding a pump rotating shaft;
A guide vane boss that receives lubricating water in the protection tube, a mechanical seal that seals the lubricating water in the boss with liquid pumped by the pump, return piping that returns the lubricating water in the guide vane boss to the accumulator tank, and a pump discharge. A closed type compensation tank into which the discharge pressure water in the pipe is introduced via compensation piping, and air in the compensation tank is supplied into the accumulator tank according to the amount of the discharge pressure water introduced to adjust the pressure in the accumulator tank. 1. A bearing lubricating water supply device comprising: a communication pipe equipped with a check valve that varies the amount of water.