JP2610356B2 - Shaft sealing device for pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention alleviates the thermal stress of the pump shaft of a reactor recirculation pump for efficiently circulating the primary cooling water of a light water reactor, for example. For a shaft seal device for a pump.

(Prior art) Reactor recirculation pumps used in light water reactors are high-capacity pumps that handle high-temperature, high-pressure pure water. It is a volume pump.

Hereinafter, a reactor recirculation pump incorporating a conventional pump shaft sealing device will be described with reference to FIG. Tenth
In the drawing, reference numeral 1 denotes an upper casing, in which a seal chamber 3 formed by a shaft sealing cover for sealing a pump shaft 2 is provided. A mechanical seal 4 is provided in the seal chamber 3 so as to surround the side surface of the pump shaft 2. A shaft sealing water injection pipe 5 is provided at an upper part of the seal chamber 3, and a heat exchanger 6 is provided around the outer periphery of the seal chamber 3. The upper end of the pump shaft 2 is connected to a motor shaft 8 via a flexible joint 7. A labyrinth portion 9 is formed on the lower side surface of the pump shaft 2 such that a large number of annular grooves are stacked in the axial direction, and an impeller 10 is further mounted below the labyrinth portion 9. The impeller 10 is disposed in a lower casing 11 serving as a pump chamber. The lower casing 11 is connected to a base 12 connected to a lower end of the upper casing 1 by being tightened with bolts 13. Casing cover between base 12 and lower casing 11
14 are interposed. An underwater bearing 15 is attached to the lower end surface of the casing cover 14, and the underwater bearing 15 supports the shaft of the impeller 10. The lower casing 11 has a suction port 16 for injecting reactor primary cooling water, that is, pump water (hot water), and a discharge port 17 for discharging primary cooling water sucked by the impeller 10 from the suction port 16 below. Have been. Also, pump shaft 2
A circulating blade 18 is attached to, and the circulating blade 18 circulates the shaft sealing water in the seal chamber 3. In the figure, reference numeral 19 denotes a flange of the upper casing 1. Thus, the conventional pump shaft 2
Is surrounded by a mechanical seal 4 and an inner surface of a casing cover 14 and serves as a pump to suck and discharge pump water, and a pump shaft 2 for rotating the impeller 10.
An underwater bearing 15 for supporting the shaft of the impeller 10 attached to the pump shaft 2; a casing cover 14 for attaching the underwater bearing 15 to separate the upper casing 1 from the lower casing 11. Consists of Further, the shaft sealing water, that is, the cold water portion in the seal chamber 3 containing the mechanical seal 4 and the hot water portion filled with the pump water such as the impeller 10 and the underwater bearing were attached to the pump shaft 2. It is divided by the circulation blade 18 and the labyrinth part 9. The heat exchanger 6 is for cooling the shaft sealing water to prevent the mechanical seal 4 from being heated and damaged in case the injection of the shaft sealing water is stopped. The shaft sealing water is for sealing the mechanical seal 4 so that the pump water does not flow.

(Problem to be Solved by the Invention) A cylindrical shape is provided between the labyrinth portion 9 formed on the pump shaft 2 and the inner surface of the casing cover 14 in the conventional shaft sealing device for a reactor recirculation pump shown in FIG. A narrow channel is formed. For example, in the case of a boiling water reactor, the temperature of the reactor recirculating water, that is, the pump water is considerably high temperature hot water, and the inside of the seal chamber 3 is cold water in which the shaft sealing water circulates.
There is a considerable temperature difference between the seal chamber 3 and the pump chamber. Shaft sealing water (also called purge water) is injected from outside through a shaft sealing water inflow pipe 5 in order to keep the temperature of the seal chamber 3 in a cold water state.

However, in such a pump shaft sealing device, a large temperature difference, that is, a large density difference occurs due to hot water in the lower pump chamber and cold water in the upper seal chamber 3, so that the cold / heat interface is unstable due to gravity. The pump water (hot water) having a small density rises from the pump chamber in the lower casing 11 to the labyrinth portion 9, and the shaft sealing water (cold water) injected from the upper seal chamber 3 descends the labyrinth portion 9. . For this reason, the cold / heat interface is wavy, and the temperature of the labyrinth portion of the pump shaft 2 and the casing cover 14 has a large temperature fluctuation with a maximum amplitude of the temperature difference between the hot water and the cold water, thereby generating thermal stress on the pump shaft. There is a problem that causes thermal fatigue.

Further, when the flow rate of the shaft sealing water changes, the cold / hot interface moves up and down (axial direction). For this reason, the pump shaft 2 and the casing cover of the labyrinth portion 9 which is a cold / hot boundary portion
Large thermal stress is likely to occur in the 14 metal parts. When the thermal stress is repeated many times over many years, the labyrinth 9
May have cracks due to thermal fatigue.

Therefore, there is a demand for a shaft sealing device for a pump shaft which does not cause a large temperature fluctuation even if the flow rate of the shaft sealing water and the rotation speed of the pump slightly change.

The present invention has been made to solve the above problems,
It is an object of the present invention to provide a pump shaft sealing device capable of relieving temperature fluctuation at a cold / hot boundary to prevent thermal fatigue and significantly improving reliability in structural strength.

[Configuration of the invention]

(Means for Solving the Problems) The present invention provides a pump shaft provided in an upper casing,
A mechanical seal provided in a seal chamber for sealing the pump shaft, a circulating mechanism for circulating shaft seal water in the seal chamber, and a lower casing connected to the upper casing and the lower casing. A shaft sealing device for a pump having a labyrinth portion formed on a pump shaft, a casing cover provided between the upper casing and the lower casing, and an impeller attached to the pump shaft in the lower casing. Wherein a shaft sealing water cooling device for cooling shaft sealing water near an upper portion of the casing cover and a shaft sealing water heating device for heating shaft sealing water near a lower portion of the casing cover are provided. The heating device is provided with a plurality of vertical grooves in the pump shaft, a lower shaft sleeve having a plurality of small holes provided so as to cover the vertical grooves, and the casing cover. A heating cylinder having a hot water inflow hole for primary cooling water provided in a submerged bearing attached to a lower end face thereof and having a flow path through which hot water flows so as to heat the side surface of the lower shaft sleeve in communication with the hot water inflow hole. Is provided below the casing cover.

(Function) By removing the conventional heat exchanger by the shaft sealing water cooling device, the shaft sealing structure is made compact, and the temperature difference between the cold and hot water flowing into the labyrinth part is reduced by the shaft sealing water heating device. The temperature amplitude of the temperature fluctuation is set below the thermal fatigue occurrence limit. By forming the shaft sealing water heating device in a multi-cylindrical body, the temperature of the shaft sealing water gradually increases as it goes upward, the lower the density is higher, the upper the density is lower, and the flow of cold and hot water is stable against gravity. Can be Further, by providing the vertical groove in the shaft sealing water rising flow portion, the cold / hot interface can be stabilized by centrifugal force.

(Example) A first example of a shaft sealing device for a pump according to the present invention will be described with reference to Figs. 1 to 5. In the figure,
The same parts as those in FIG. 10 are described with the same reference numerals.

In FIG. 1, a pump shaft 2 is provided in an upper casing 1.
Is provided with a seal chamber 3 formed by a shaft sealing cover for sealing the shaft. A mechanical seal 4 is provided in the seal chamber 3 so as to surround the side surface of the pump shaft 2. A shaft sealing water injection pipe 5 for flowing shaft sealing water for cooling the mechanical seal 4 is provided at an upper portion of the seal chamber 3. The upper end of the pump shaft 2 is connected to a motor shaft 8 via a flexible joint 7, and an impeller 10 is attached to a lower portion. By driving a motor (not shown), the pump shaft 2 rotates, and the impeller 10 also rotates. . The impeller 10 is disposed in the lower casing 11, that is, in the pump chamber. The lower casing 11 is connected to a base 12 connected to a lower end of the upper casing 1 by tightening bolts 13. A casing cover 14 is interposed between the base 12 and the lower casing 11. An underwater bearing 15 is attached to the lower end surface of the casing cover 14, and the underwater bearing 15 supports the shaft of the impeller 10. A lower casing 11 has a suction port 16 through which reactor primary cooling water, that is, pump water (hot water) flows, and an impeller 10 through the suction port 16.
A discharge port 17 for discharging the primary cooling water sucked in at the step is formed. A circulating blade 18 is attached to the pump shaft 2, and the circulating blade 18 circulates shaft sealing water in the seal chamber 3. In the figure, reference numeral 19 denotes a flange of the upper casing 1, which is connected to a motor chamber (not shown). The pump shaft 2 is provided with upper and lower cylindrical shaft sleeves 20 (20a, 20b) so that temperature fluctuation is not transmitted to the mechanical seal 4 and the pump shaft 2. A shaft sealing water cooling device 21 for cooling shaft sealing water in the seal chamber 3 is provided on a side surface of the upper shaft sleeve 20a.
And a shaft sealing water heating device 22 located on the lower surface of the casing cover 14 for heating shaft sealing water.

As shown in the enlarged view of FIG. 2, the shaft sealing water cooling device 21 is an inflow of cooling water provided in a wall of a shaft sealing cover 24 that forms the sealing chamber 3 fixed to the casing cover 14 with bolts 23. It comprises a passage 25 and an outflow passage 26 communicating with the inflow passage 25. The lower portions of these flow paths 25 and 26 are formed in a U-shape. A rotating cylinder 27 having a lower part sandwiched in a U-shape and an upper part protruding into the seal chamber 3 is provided, and the rotating cylinder 27 is fixed to the lower shaft sleeve 20b by tightening with a bolt 28. . Reference numeral 29 in the drawing denotes a holding flange that forms the upper part of the seal chamber 3, which holds the holding members 30, 31 of the mechanical seal 4, and bolts 32 on the shaft sealing cover 24.
Fixed at. A seal chamber 3 for sealing the pump shaft 2 is provided.
The upper shaft sleeve 20a located inside is fixed to a sleeve mounting upper flange 33 with bolts.

The shaft sealing water heating device 22 is located below the lower shaft sleeve 20b and is provided near the underwater bearing 15 as shown in an enlarged manner in FIGS. That is, the shaft sealing water heating device 22 is provided with a hot water inflow hole 35 of the primary cooling water in the underwater bearing 15,
A heating cylinder having a flow path 36 communicating with the hot water inlet 35 and through which hot water flows so as to heat the side surface of the lower shaft sleeve 20b.
37 is provided on the lower surface of the casing cover 14. In addition, the lower part of the lower shaft sleeve 20b is thinly cut so that the rotating cylinder 20c is cut.
The rotary cylinder 20c is provided with a large number of small holes 38. Thus, the hot water flow path 36 provided in the casing cover 14 of the shaft sealing water heating device 22 and the lower shaft sleeve 20b
And a rotating cylinder 20c attached to the rotating cylinder 20c.

As shown in FIG. 5 (a), a plurality of vertical grooves 39 are provided in a part of the pump shaft 2. Hot water is blown out from the plurality of small holes 38 of the rotary cylinder 20c provided so as to cover the vertical groove 39, and is mixed with the shaft sealing water by a pump action by centrifugal force accompanying the rotation of the vertical groove 39.

As described above, in the present embodiment, the lower casing 11 that forms the pressure-resistant portion, the impeller 10 that is a pump unit, and the impeller
A casing cover 14 that supports the pump shaft 2 for rotating the pump 10 and the underwater bearing 15 and constitutes a pressure-resistant portion; a mechanical seal 4 that seals the pressure-resistant portion of the pump shaft 2; The shaft sealing water is injected into the sealing chamber 3 from the outside so that hot pump water does not flow into the mechanical seal 4 and the supply of the shaft sealing water is stopped by any chance. The shaft sealing water cooling device 21 provided in case
Sealed water heating device consisting of hot water channel 36 and heating cylinder 37 inside
It consists of 22.

Therefore, according to the present embodiment, as shown in FIG. 5 (a), a plurality of vertical grooves 39 provided in a part of the pump shaft 2 cause a pumping action by centrifugal force to cover the vertical grooves 39. In this way, hot pump water is blown out from the small hole 38 provided in the rotary cylinder 20c, and as shown in FIG.
Is mixed with the shaft sealing water (cold water) to produce an effect of raising the temperature of the shaft sealing water. Further, hot water blown out from the underwater bearing 15 is circulated in a heating cylinder 37 provided below the casing cover 14.

FIG. 5 (b) shows the temperature distribution in the height direction of the labyrinth portion in the axial direction of the pump shaft 2, and it can be seen that the temperature increases from the upper end of the vertical groove 39 downward.
This indicates that the temperature is lower than above the labyrinth.

Therefore, the temperature of the shaft sealing water is increased by heating or mixing with hot water in the labyrinth portion 9 where the shaft sealing water (cold water) falls,
The temperature difference between the pump water (hot water) in the lower casing 11, that is, the pump chamber, is made small, so that the temperature amplitude of the temperature fluctuation can be made smaller than the thermal fatigue occurrence limit.

FIG. 6 (a) shows only the main part of the second embodiment of the present invention, and the same parts as those in FIG. 4 are denoted by the same reference numerals, and the description of the other parts is omitted.

That is, the lower shaft sleeve 20b surrounding the pump shaft 2
Is provided with a rotating cylinder 20c, and the rotating cylinder 20c is provided with a large number of small holes 38. The rotary cylinder 20c has a large-diameter cylindrical body 20d having a bottom connected to form a cylindrical cylindrical double cylinder. A shaft-sealed water heating cylinder 40 suspended below the casing cover 14 in the double cylinders 20c and 20d.
Is inserted. A partition tube 41 having a flow path 42 is inserted into the heating cylinder 40 to form a triple heating cylinder. Therefore, the quintuple cylindrical body is provided in the pump shaft 2 and the casing cover 14 together with the double cylindrical body and the triple cylindrical body.

According to the second embodiment, a triple heating cylinder is nested in a double rotating cylinder connected to the shaft sleeve 20b to form a multi-cylinder structure, and a shaft sealing water upflow portion 43 is provided. .

According to the second embodiment, as shown in FIG. 6 (b), the temperature of the shaft sealing water gradually increases as the temperature increases due to the heat input q. Therefore, the flow of cold / hot water can be stabilized.

FIG. 7 shows a third embodiment of the present invention.
Only the main part is shown similarly to the figure. That is, in the third embodiment, a large-diameter rotary cylinder 20e is directly connected to a lower sleeve 20b provided on the pump shaft 2 at the bottom thereof, and a partition cylinder suspended from the casing cover 14 in the cylinder 20e. 44 is that a flow path 45 is provided. The rotating cylinder 20
A vertical groove 46 is formed on the inner surface of e.

According to this third embodiment, FIGS. 7 (b) and (c)
As shown in the figure, the temperature distribution in the height direction of the shaft sealing water rising flow part 43 becomes higher as it goes upward, while the shaft sealing water rising flow part
In the radial temperature distribution of 43, the temperature decreases along the outward direction.

Therefore, if the vertical groove 46 is provided in the shaft sealing water upflow portion 43, the interface between the cold and hot water can be stabilized by the centrifugal force.

FIG. 8 shows a fourth embodiment of the present invention.
As in the drawing, only the essential parts are shown, and the same parts as those in FIG. 3 are denoted by the same reference numerals, and the description of the overlapping parts will be omitted.

In the fourth embodiment, a plurality of ring-shaped labyrinths 47 are formed on the inner surface of the inner cylinder 37a of the double-shaft water-sealing heating cylinder 37 hung on the lower surface of the casing cover 14 without using the shaft sleeve 20b. is there.

According to the fourth embodiment, the temperature of the shaft sealing water is raised only by the shaft sealing water heating cylinder 37, and the labyrinth 47 can prevent the rotation in the cold / hot water interface direction.

FIG. 9 shows a fifth embodiment of the present invention.
As in the figure, only the main parts are shown, and overlapping parts are omitted.

In the fifth embodiment, the inner cylinder in the fourth embodiment is used.
This is because a large number of small holes 48 inclined downward are provided in 37a, and the hot water flow path 36 at the lower end of the heating cylinder 37 is closed.

According to the fifth embodiment, the hot water inflow hole 35 of the underwater bearing 15 is provided.
Of hot water flowing from the pump shaft 2 through the hot water flow passage 36 through a large number of inclined small holes 48 and mixed with cold water flowing out between the pump shaft 2 and the casing cover 14 to reduce the temperature difference with the hot water. In addition, the rotation of the cold / hot water interface in the axial direction can be prevented.

An embodiment of the shaft sealing device for a pump according to the present invention is summarized as follows.

(1) Used for a shaft sealing device of a pump shaft of a primary cooling water recirculation pump of a light water reactor, the pump shaft is sealed with a mechanical seal, and the mechanical seal is held in a seal chamber. Water is circulated, and a shaft sealing water cooling device that cools the shaft sealing water and a shaft sealing water heating device that heats the shaft sealing water are provided vertically above and below the casing cover.

(2) The shaft-sealing water cooling device comprises a circulation channel for cooling water provided in the wall of the shaft-sealing cover forming the seal chamber, and a rotating cylinder attached to the upper shaft sleeve.

(3) The shaft sealing water heating device comprises a hot water flow path provided in the casing cover, and a rotating cylinder attached to the lower shaft sleeve.

(4) In the shaft sealing water heating device, a plurality of vertical grooves are provided in a part of the pump shaft, and a plurality of small holes are provided in the rotating cylinder so as to cover the vertical grooves.

(5) A shaft sealing water heating cylinder shall be attached to the lower part of the casing cover.

(6) The shaft sealing water heating cylinder shall have a flow path through which hot water blows out from the underwater bearing.

(7) The shaft sealing water heating cylinder has a multi-cylinder structure and is provided with an upward flow portion of the shaft sealing water.

(8) A vertical groove is provided in the upflow portion of the shaft sealing water to stabilize the interface between cold and hot water by centrifugal force.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, the temperature fluctuation of the cold / hot mixing part in the shaft sealing part of a pump shaft can be eased, and thermal fatigue can be prevented. Therefore, no crack is generated in the shaft sealing portion, and the reliability in structural strength can be greatly improved.

This leads to further improvements in the reliability and safety of nuclear power plants, and is extremely useful in industry.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a reactor recirculation pump incorporating a pump shaft sealing device according to the present invention, and FIG. 2 is an enlarged view of the vicinity of a seal chamber and a shaft sealing water cooler in FIG. Longitudinal section, third
The figure is an enlarged longitudinal sectional view showing the vicinity of the shaft sealing water heating device in FIG. 1, FIG. 4 is an enlarged longitudinal sectional view showing an essential part in FIG. 3, and FIG. 5 (a) is FIG. FIG. 5 (b) is a characteristic diagram showing the temperature distribution in the height direction of the labyrinth part corresponding to FIG. 5 (a), and FIG. 6 (a) is a perspective view of the present invention. FIG. 6 (b) is an enlarged longitudinal sectional view showing the vicinity of the shaft sealing water heating cylinder in the second embodiment, FIG. 6 (b) is a characteristic diagram showing the temperature distribution of the purge water rising section corresponding to FIG. 6 (a), FIG. 7A is a longitudinal sectional view of a main part in a third embodiment of the present invention, and FIG. 7B is a characteristic diagram showing a temperature distribution in a height direction of a purge water rising portion in FIG. 7A. FIG. 7 (c) is a characteristic diagram showing the temperature distribution in the radial direction of the purge water rising portion in FIG. 7 (a), and FIGS. 8 and 9 are diagrams each showing a main part of another embodiment of the present invention. A longitudinal section showing, FIG. 10 is a longitudinal sectional view showing the incorporated reactor recirculation pump of conventional shaft sealing device for a pump. DESCRIPTION OF SYMBOLS 1 ... Upper casing, 2 ... Pump shaft, 3 ... Seal chamber, 4 ... Mechanical seal, 5 ... Shaft sealing water injection pipe, 6 ... Heat exchanger, 7 ... Flexible joint, 8 ... Motor Shaft 9 Labyrinth part 10 Impeller 11 Lower casing 12 Base 13 Bolt 14 Casing cover 15 Submerged bearing 16 Suction port 17 … Discharge port, 18… Circulation vane, 19 …… Top flange, 20 …… Shaft sleeve, 21 …… Shaft sealing water cooling device, 22 …… Shaft sealing water heating device, 23 …… Bolt, 24 …… Shaft sealing Cover, 25: Inflow channel, 26: Outflow channel, 27: Rotating cylinder, 28: Bolt, 29: Pressing flange, 30, 31: Holding member, 32: Bolt, 33: Upper part Flange, 34 bolt, 35 hot water inflow hole, 36 hot water flow passage, 37 heating cylinder, 38 small hole, 39 vertical groove, 40 heating cylinder, 41/44 …… Partition cylinder, 42 ・ 45 …… Flow path, 43 …… Upflow section, 44 …… Partition cylinder, 46 …… Vertical groove, 47 …… Ring labyrinth, 48 …… Slope small hole.

 ──────────────────────────────────────────────────続 き Continued on the front page (73) Patent holder 999999999 Hokuriku Electric Power Co., Inc. 15-1, Ushijima-cho, Toyama-shi, Toyama (73) Patent holder 999999999 Chugoku Electric Power Co., Inc. 4-33 Komachi, Naka-ku, Hiroshima-shi, Hiroshima (73) Patent holder 999999999 Japan Atomic Power Company 1-6-1, Otemachi, Chiyoda-ku, Tokyo (73) Patentee 999999999 Hitachi, Ltd. 4-6-1 Kanda Surugadai, Chiyoda-ku, Tokyo (73) Patent right 999999999 EBARA CORPORATION 11-1 Haneda Asahi-cho, Ota-ku, Tokyo (72) Inventor Nao Narabayashi 1 Toshiba-cho, Komukai-Toshiba-cho, Kawasaki-shi, Kanagawa Prefecture Inside Toshiba Research Institute, Inc. (72) Hiroshi Miyano (72) Inventor Kazuyuki Kobashi Komukai Toshiba Town, Kawasaki City, Kanagawa Prefecture Address: Toshiba Research Institute, Inc. (72) Inventor Tetsuzo Yamamoto 1, Komukai Toshiba-cho, Saiwai-ku, Kawasaki, Kanagawa Prefecture (72) Inventor Takenori Ishiyama 1, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Address: Toshiba Research Institute, Inc. (72) Inventor: Nobuhiko Tanaka 8, Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Toshiba-Yokohama Office (56) References JP-A-1-216992 (JP, A)

Claims (1)

(57) [Claims] A pump shaft disposed in an upper casing; a mechanical seal provided in a seal chamber for sealing the pump shaft; a circulating mechanism for circulating shaft seal water in the seal chamber; A labyrinth portion formed on the pump shaft located at a position separating the inside of the lower casing connected to the lower end of the casing, a casing cover provided between the upper casing and the lower casing,
A pump shaft sealing device having an impeller attached to the pump shaft in the lower casing, a shaft sealing water cooling device for cooling shaft sealing water near an upper portion of the casing cover, and a lower portion of the casing cover. A shaft sealing water heating device for heating shaft sealing water is provided in the vicinity, and the shaft sealing heating device is provided with a plurality of vertical grooves on the pump shaft, and provided with a plurality of small holes provided so as to cover the vertical grooves. A hot water inflow hole for primary cooling water is provided in a lower shaft sleeve having a lower shaft sleeve and an underwater bearing attached to a lower end surface of the casing cover, and a side surface of the lower shaft sleeve is heated by communicating with the hot water inflow hole. A shaft sealing device for a pump, comprising: a heating cylinder having a flow path through which hot water flows, provided at a lower portion of the casing cover.