JP3450824B2 - Internal pump - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet motor type internal pump attached to the bottom of a reactor pressure vessel for circulating a reactor coolant.

[0002]

2. Description of the Related Art In a boiling water nuclear power plant, a coolant is supplied to a core in a nuclear reactor, the coolant is heated in the core and the steam generated is guided to a turbine to drive a generator to generate electricity. . In recent years, so-called improved boiling water nuclear reactors (hereinafter referred to as “ABW
R) has been proposed, and in this ABWR, an internal pump attached to the bottom of the reactor pressure vessel is adopted as a pump for circulating the coolant in the reactor. The coolant in the reactor pressure vessel descends along the side wall surface of the pressure vessel on the outer peripheral side in the pressure vessel, and is provided at a plurality of circumferential positions (for example, 10 locations) in the vicinity of the outer peripheral side bottom portion in the pressure vessel. After being sucked into the null pump, it is pressurized and discharged, rises from the lower plenum below the pressure vessel, and is circulated to the core.

A conventional internal pump is, for example, as shown in FIG. 1 of Japanese Patent No. 2714020, an impeller (impeller) located at the uppermost position and rotationally driven, and located below the impeller. Fixed guide vane (diffuser)
It has and. The impeller is fixed or connected to a vertical rotating shaft (shaft) that penetrates the bottom surface of the pressure container, and this rotating shaft is driven by a wet motor unit provided outside the pressure container. Rotate by doing. A thrust disk rotatably supported in the vertical direction by upper and lower thrust bearings is arranged at the lower end of the rotary shaft. The rotary shaft is rotatably supported in the radial direction by upper and lower radial bearings (bearing means) above and below the wet motor unit.

In the above structure, the reactor coolant flows into the impeller from above, is pressurized by the impeller, is then introduced into the diffuser, and after the pressure is recovered, flows out below the diffuser. On the other hand, at this time, the motor cooling water that cools the inside of the wet motor section is discharged from the auxiliary impeller by the rotation of the thrust disk, and then rises inside the motor casing (or pump casing or pump housing) on the outer peripheral side of the wet motor section. To cool the rotor (motor rotor) and stator (motor stator),
Further, it is guided to a heat exchanger via a pipe outside the pump casing and cooled. The cooled cooling water is again introduced into the auxiliary impeller through the pipe.

[0005]

The internal pump of the above-mentioned prior art, although not particularly shown or described in detail in the publication, usually has an upper bearing means for supporting the outer peripheral side of the shaft through a radial gap. The outer peripheral side of the upper bearing means is supported by a bearing housing provided on the inner peripheral side of the pump casing, and a bearing cover is provided on the upper part of the upper bearing means. Then, the cooling water sent to the wet motor part by the auxiliary impeller installed at the lower part of the wet motor is used to form the first flow path part formed by the radial gap between the upper bearing means and the shaft, between the bearing cover and the pump casing. Through a cooling water flow passage including a second flow passage portion formed by a gap and a third flow passage portion (through hole) penetrating the bearing housing in the radial direction, to a nozzle portion provided in the pump casing , The structure is such that the nozzle portion circulates to a heat exchanger provided outside the pump casing.

This is because of the following reasons. First,
Since the internal pump is installed so as to project from the bottom of the reactor pressure vessel, it is advantageous to make the axial length of the shaft as short as possible.Therefore, the members inside the pump casing should be installed in the minimum necessary space. Will be configured. In such a structure, since the upper bearing means is provided in the upper portion of the pump casing, the cooling water is generated from the radial gap between the inner peripheral side of the upper bearing means and the outer peripheral side of the shaft opposite to the inner peripheral side. After being guided to the upper part of the first flow path part, the structure is such that it is guided to the second flow path part which is a gap between the upper part of the bearing cover and the pump casing.

At this time, in order to secure the concentricity of the upper bearing means and the bearing cover, it is necessary to support the upper bearing means and the bearing cover with some member from the fixed pump casing. A bearing housing is provided on the outer peripheral side of the bearing means. The bearing housing is provided with a ring-shaped flange portion that protrudes upward toward the inner peripheral side of the pump casing immediately outside the bearing means, and the flange portion abuts the pump casing to ensure good concentricity. Has become. In this case, this flange portion obstructs the flow of the cooling water. Therefore, in order to finally guide the cooling water that has been introduced into the second flow path portion to the nozzle portion of the pump casing, the ring-shaped flange Through holes must be provided at a plurality of locations in the circumferential direction of the section to allow cooling water to pass therethrough. However, since the nozzle portion is usually provided only at one location in the pump casing, if the heights of the through holes at a plurality of circumferential positions are the same as the height of the nozzle portion, the through hole at the circumferential position closest to the nozzle portion is formed. Only the cooling water flow is concentrated, and the cooling water flow is less likely to flow from the other through holes toward the nozzle portion, and the cooling water flow distribution is biased in the circumferential direction, which is not preferable. Therefore,
By lowering the position of each through hole provided in the ring-shaped flange portion below the height of the nozzle portion, once the cooling water drops downward and flows out from the through hole to the outer peripheral side of the flange portion, it reaches the height of the nozzle portion. By making the flow path structure to rise,
Figure Rukoto considered the uniformity of flow distribution of the cooling water.

However, in this case , the cooling water is passed through the first bearing portion between the upper bearing means and the shaft → the second passage portion between the bearing cover and the pump casing → the first radial passage through the bearing housing. 3 channel parts → 3rd
Since it flows like a nozzle portion provided at a position higher than the flow path portion, this portion has a relatively large pressure loss and becomes a resistance against the circulation of the motor cooling water.

Since the internal pump is one of the most important facilities that influence the operation of a nuclear power plant,
High reliability is required. Further, generally, even when the pump is stopped due to the loss of the motor drive power source or the like, the design is required to maintain the rotation for a certain period of time by the inertial force and prevent the rapid decrease of the reactor coolant flow rate. Particularly, with the recent trend of rationalization of equipment, there is a need for higher inertia of the internal pump.

In order to cope with this, for example, as shown in FIG. 2 of the above-mentioned Japanese Patent No. 2714020, in order to increase the moment of inertia of the pump rotor on the rotary shaft above the rotor (motor rotor). It has been proposed to provide a flywheel to reduce the rotational speed reduction speed when the motor drive power supply is lost. When such a flywheel is provided, while high inertia can be realized, the flywheel becomes a flow path resistance to the circulation of the motor cooling water. Therefore, improvement of the motor cooling performance is a technical problem. It is one.

In order to improve the motor cooling performance, it is possible to increase both the capacity of the heat exchanger and the amount of motor cooling water, but increasing the capacity of the heat exchanger leads to an increase in the size of equipment and is not preferable. Therefore, it is desirable to take measures to improve the motor cooling performance without increasing the size of the equipment due to the increase of the motor cooling water amount.

The present invention has been made in view of the above matters, and an object thereof is to make the flow distribution of cooling water uniform.
Another object of the present invention is to provide an internal pump capable of improving the motor cooling performance without increasing the size of the equipment by reducing the pressure loss of the motor cooling water flow path.

[0013]

(1) In order to achieve the above object, the present invention has a pump casing installed at the bottom of a reactor pressure vessel, and penetrates the reactor pressure vessel inside the pump casing. A shaft, an impeller fixed to the shaft in the reactor pressure vessel, a wet motor portion installed outside the reactor pressure vessel for rotating the shaft, and a wet motor portion provided above and below the wet motor portion, respectively. Upper and lower bearing means, and the upper bearing means supports the outer peripheral side of the shaft via a radial gap, and the outer peripheral side of the upper bearing means is provided on the inner peripheral side of the pump casing. It is supported by a bearing housing, a bearing cover is provided on the upper bearing means, and an auxiliary device is installed on the lower part of the wet motor. The cooling water sent to the wet motor section by an impeller is formed of a first flow path section formed of the radial gap between the upper bearing means and the shaft, and a gap formed between the bearing cover and the pump casing. Through a cooling water flow passage including a second flow passage portion and a third flow passage portion that is provided to penetrate the bearing housing in the radial direction, to a nozzle portion provided in the pump casing,
In internal pump for circulating the heat exchanger provided outside the pump casing from the nozzle portion, said Bruno
The sled part is higher than the third flow path part of the pump casing.
Together have provided at a position on the upstream side portion of the downstream side portion of the second flow path part of the first flow path portion, the flow than the upstream side
A flow path area enlarged portion having a large road area is provided.

[0014] without incurring increased shaft axis length, an upper bearing means, in order to ensure the concentricity of such bearing cover, the outer peripheral side of the shaft support via the radial clearance in the upper bearing means and the upper bearing means When the outer peripheral side is supported by the bearing housing provided on the inner peripheral side of the pump casing, and further the bearing cover is provided on the upper part of the upper bearing means, the motor cooling water flows between the upper bearing means and the shaft in the first flow path portion → The second flow path portion between the bearing cover and the pump casing → the third flow path portion that penetrates the bearing housing in the radial direction → the nozzle portion provided at a position higher than the third flow path portion . this
As described above, once the cooling water drops downward,
Direction and then rise to the height of the nozzle part
The cooling water flow direction distribution
Can be made uniform. However, in this case
In this case , the cooling water flow path has a complicated shape, resulting in a relatively large pressure loss and resistance to the circulation of the motor cooling water.

Therefore, in the present invention, between the downstream side of the first flow path portion and the upstream side of the third flow path portion, a taper portion, a rounded portion, and a step portion are formed at the corners on the inner peripheral side of the bearing cover. And the like, or a through hole that penetrates the bearing cover in the radial direction is provided to form the channel area enlarged portion. As a result, since the flow passage area is increased, the resistance in the flow passage when the motor cooling water passes can be reduced and the motor cooling water can be made to flow smoothly, so that the pressure loss can be reduced. By reducing the pressure loss, the motor cooling water flow rate can be increased due to the relationship between the auxiliary impeller lift characteristic and the in-casing pressure loss characteristic. Therefore,
The motor cooling performance can be improved without increasing the size of the equipment.

(2) In order to achieve the above object,
The invention is a pump case installed at the bottom of the reactor pressure vessel.
And the reactor pressure volume inside the pump casing.
A shaft that penetrates the reactor and the inside of the reactor pressure vessel
An impeller fixed to a shaft and the reactor pressure vessel
A wet machine installed outside that drives the shaft to rotate.
And the wet motor section above and below, respectively.
Upper and lower bearing means, and the upper part
The bearing means has a radial clearance on the outer peripheral side of the shaft.
Support through the outer peripheral side of the upper bearing means,
Bearing housing provided on the inner peripheral side of the pump casing
Supported on the upper bearing means by means of a bearing.
Was installed under the wet motor.
Cooling sent to the wet motor section with an auxiliary impeller
Water between the upper bearing means and the shaft
The first flow path portion including the radial gap, the bearing cover
Second, which comprises a gap between the bar and the pump casing
Radially penetrates the flow path and the bearing housing
Through the cooling water flow path including the third flow path part provided by
Lead to the nozzle provided on the pump casing,
To the heat exchanger installed outside the pump casing.
In the internal pump,
Provided at a position higher than the third flow passage of the pump casing
And the third flow from the downstream side portion of the first flow path portion.
A flow path area expansion part is provided between the upstream part of the road part,
Set the outer diameter D2 of the bearing cover to the upper bearing
Than the inner diameter D1 of the pump casing at the top of the
Enlarge. As a result, the flow passage surface passes through the first flow passage portion.
The motor cooling water whose flow direction has been changed in the product expansion section is
It flows into the area on the inner peripheral side of the inner diameter D1 of the pump casing.
The bearing cover and po
Flow into the second flow path that is a gap between the pump casing and
Can be crowded. ( 3 ) In the above (1) or (2) , preferably, at least one of a tapered portion, a rounded portion, and a stepped portion is provided at an inner peripheral side corner portion of the bearing cover, so that the flow passage area is increased. Form an enlarged portion.

( 4 ) In the above (1), and preferably, the flow passage area enlarged portion is formed by providing a through hole that penetrates the bearing cover in the radial direction.

( 5 ) In the above item ( 4 ), more preferably, a plurality of the through holes are provided in the circumferential direction of the bearing cover, and the sizes of the through holes are as follows.
A plurality of types are set according to the distance between each position and the nozzle portion.

Thus, for example, by setting the cross-sectional area of the through hole to increase as the distance from the nozzle portion increases, the resistance when the motor cooling water passes through the through hole can be reduced as the distance from the nozzle portion increases. Therefore, the motor cooling water flows more uniformly in the circumferential direction. Therefore, the motor cooling water flow rate can be increased more reliably.

( 6 ) In order to achieve the above object, the present invention also provides a pump casing installed at the bottom of a reactor pressure vessel, a shaft that penetrates the reactor pressure vessel inside the pump casing, and the atom. An impeller fixed to the shaft in a reactor pressure vessel, a wet motor unit installed outside the reactor pressure vessel to rotate and drive the shaft, and upper and lower bearing means provided above and below the wet motor unit. The upper bearing means supports the outer peripheral side of the shaft via a radial gap, and supports the outer peripheral side of the upper bearing means by a bearing housing provided on the inner peripheral side of the pump casing. A bearing cover is provided on the upper part of the bearing means, and the auxiliary impeller installed on the lower part of the wet motor is used for the wetting. Cooling water sent to the motor section is formed by the first flow path section formed by the radial clearance between the upper bearing means and the shaft, and the second flow path formed by the clearance between the bearing cover and the pump casing. Department,
And through a cooling water flow passage including a third flow passage portion that penetrates the bearing housing in the radial direction, to a nozzle portion provided in the pump casing, and from this nozzle portion, heat exchange provided outside the pump casing. In an internal pump that circulates in a container,
If it is installed at a position higher than the third flow path portion of the housing,
At the upper end portion of the first flow path portion, a flow guide means for guiding the flow of the cooling water from the axially upward direction to the radially outward direction is provided.

The motor cooling water has a first flow passage between the upper bearing means and the shaft, a second flow passage between the bearing cover and the pump casing, and a third flow passage radially passing through the bearing housing. Part → the nozzle part provided at a position higher than the third flow path part, the cooling water flow path has a complicated shape, resulting in relatively large pressure loss and resistance to circulation of the motor cooling water. Become. Especially the first
In the flow passage portion, the motor cooling water flows vertically upward through the gap between the upper bearing means and the shaft, but in the second flow passage portion, the motor cooling water flows radially outward between the bearing cover and the pump casing, so This results in a pressure loss due to the turning.

Therefore, in the present invention, a flow guide means for guiding the flow of the cooling water from the axially upward direction to the radially outward direction is provided at the upper end portion of the first flow path portion. As a result, the motor cooling water that has flowed through the first flow passage portion in the radial gap between the upper bearing means and the shaft is smoothly transferred to the second flow passage portion on the radially outer side (between the bearing cover and the pump casing). (Gap) of the motor cooling water, it is possible to reduce the resistance in the flow passage when the motor cooling water passes and reduce the pressure loss. By reducing the pressure loss, the motor cooling water flow rate can be increased due to the relationship between the auxiliary impeller lift characteristic and the in-casing pressure loss characteristic. Therefore, the motor cooling performance can be improved without increasing the size of the equipment.

[0023]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a vertical sectional view showing the overall schematic structure of the internal pump according to the present embodiment.

1 and 2, the internal pump is installed in the reactor pressure vessel 1 and a shaft 3 penetrating the reactor pressure vessel 1 inside a pump casing 2 installed at the bottom of the reactor pressure vessel 1. Shaft 3
The impeller 4 is fixed to the reactor, the diffuser 5 located below the impeller 4 is fixed to the reactor pressure vessel 1, and the wet motor unit 6 that rotationally drives the shaft 3. The reactor coolant in the reactor pressure vessel 1 is the impeller 4
After being sucked from above the internal pump by the rotation of, the gas is discharged through the diffuser 5 and circulated to the core.

On the other hand, the motor cooling water flowing from the motor cooling water inlet 7 installed at the lower part of the pump casing 2 is boosted by the auxiliary impeller 8 inside the pump casing 2, and after passing through the gap between the lower bearing sleeve 9b and the lower bearing 10b. The wet motor unit 6 is cooled. After cooling the motor, the motor cooling water flowing in the gap between the upper bearing sleeve 9a and the upper bearing (upper bearing means) 10a changes its direction in the vicinity of the upper portion of the upper bearing 10a, and the motor cooling water nozzle 14 supplies the motor cooling water pipe. It flows to 15a. The motor cooling water whose water temperature has risen due to the cooling of the motor is cooled by the heat exchanger 16, passes through the motor cooling water pipe 15b, and again from the motor cooling water inlet 7 to the pump casing 2
Return to the inside. In such a path, the motor cooling water circulates inside the pump casing 2 and the heat exchanger 16.

In the internal pump having the basic structure and operation as in the upper part, the main part of this embodiment is the structure near the upper part of the upper bearing 10a. 2 is X in FIG.
It is a partial enlarged view showing the detailed structure of a part.

In FIG. 2 and FIG. 1 described above, the upper bearing 10a supports the outer peripheral side of the shaft 3 through a radial gap, and the outer peripheral side of the upper bearing 10a is provided on the inner peripheral side of the pump casing 2. Housing 13
The bearing cover 11 is provided above the upper bearing 10a.

With such a structure, the cooling water sent to the wet motor unit 6 by the auxiliary impeller 8 installed at the lower portion of the wet motor unit 6 as described above is used for the radial gap between the upper bearing 10a and the shaft 3. Formed of a first flow path portion 101, a second flow path portion 102 formed of a gap between the bearing cover 11 and the pump casing 2, and a flow path formed on the casing side of the bearing cover 11 so as to allow the motor cooling water to go around. Outflow hole (through hole) 1 provided through the groove 12 and the bearing housing 13 in the radial direction.
A motor cooling water nozzle (nozzle section) 1 provided at a position higher than the third flow path section 103 in the pump casing 2 through a cooling water flow path including a third flow path section 103 made of 3a.
4 to the motor cooling water pipe 15a from this nozzle 14
To the heat exchanger 16 provided outside the pump casing 2.

The greatest feature of this embodiment is that the upper corner portion of the bearing cover 11 constituting the motor cooling water flow path on the shaft 3 side (in other words, the inner peripheral side) is the taper portion 11a. The maximum diameter D2 of the tapered portion of the bearing cover is D1 <D2 so that it is at least larger than the inner diameter D1 of the pump casing 2 above the upper bearing 10a.

After cooling the motor, the motor cooling water that has passed through the gap (= first flow passage portion 101) between the upper bearing sleeve 9a and the upper bearing 10a gradually increases in velocity in the axial direction by the tapered portion 11a of the bearing cover 11. While increasing the velocity component outward in the radial direction while decreasing, the flow direction can be changed in the flow passage area enlarged portion A with a resistance in the flow passage smaller than that of the conventional structure. That is, since the flow passage area is enlarged in the flow passage area expanding portion A, the resistance in the flow passage when the motor cooling water passes can be reduced and the motor cooling water can be smoothly flowed. Therefore, the first flow path unit 1
01, the second flow passage portion 102, the flow passage groove 12, and the third flow passage portion 103 as a whole, the pressure loss can be reduced. Thereby, the motor cooling water flow rate can be increased.

At this time, since the outer corner 21a of the taper portion is located outside the corner 20 of the pump casing 2, the motor cooling water whose flow direction is changed is suppressed from flowing into the area B. It flows more smoothly into the gap between the pump casing 2 and the upper part of the bearing cover 11 (= the second flow path portion 102), goes around the motor cooling water flow path groove 12 opened on the casing side of the bearing cover 11, and flows out of the bearing housing 13. Hole 13a (= third
It is guided to the motor cooling water nozzle 14 through the flow path 103) and flows out to the motor cooling water pipe 15a.

In the present embodiment, the motor cooling water flow rate can be increased by reducing the cooling water flow path pressure loss as described above. This will be described more concretely with reference to FIG.

FIG. 3 is a characteristic diagram of the motor for explaining the increase of the motor cooling water flow rate according to the present embodiment, where the horizontal axis is the motor cooling water flow rate Q, and the vertical axis is the total head H of the auxiliary impeller 8. The pressure loss R of the motor cooling water system (cooling water flow path) is shown.

In FIG. 3, a curve S shows the performance characteristics of the auxiliary impeller 8, a curve R1 shows the pressure loss characteristics of the motor cooling water system in the case of an internal pump having a motor cooling water passage of the conventional structure, and a curve R2. Shows the pressure loss characteristics of the motor cooling water system in the case of the internal pump having the motor cooling water passage of the present embodiment.

In the conventional structure, the operating points of the auxiliary impeller 8 during the rated operation of the internal pump are the curve S and the curve R1.
And the motor cooling water flow rate is Q1.
On the other hand, in this embodiment, since the pressure loss characteristic becomes the curve R2 due to the pressure loss reduction due to the improvement of the motor cooling water flow path described above, the operating point of the auxiliary impeller shifts to P2, and the motor cooling water flow rate at this time is changed. Becomes Q2, and Q1
More than. In this way, in the present embodiment, the motor cooling water flow rate can be increased by reducing the resistance in the passage and the pressure loss based on the improvement of the motor cooling water passage. Therefore, the motor cooling performance can be improved without increasing the size of the equipment.

In the above description, the relationship between the maximum diameter D2 of the tapered portion of the bearing cover and the inner diameter D1 of the pump casing 2 above the upper bearing 10a is D1.
Although <D2 is satisfied, the invention is not limited to this as long as the effects of the present invention are obtained, and D1 ≧ D2 may be satisfied. That is, if at least the flow passage area enlarging portion A is provided, it is possible to reduce the pressure loss in the cooling water flow passage and increase the motor cooling water flow rate to improve the motor cooling performance, as compared with the conventional structure in which this is not provided. Can be improved.

Further, the present invention is not limited to the above-mentioned one embodiment, and various modifications can be made without departing from the technical idea thereof. Hereinafter, each of these modifications will be described in order.

(1) Structure with Rounded Portions FIG. 4 is a partially enlarged view showing a detailed structure in the vicinity of the upper portion of the upper bearing 10a according to this modification and corresponds to FIG. 2 described above.

In FIG. 4, in this modification, an R-shaped rounded portion 11b is provided instead of the tapered portion 11a according to the embodiment of the present invention. At this time, similar to the above
The center diameter D2 of the rounded portion of the bearing cover 11 is D1 <D2 so that it is at least larger than the inner diameter D1 of the pump casing 2 above the upper bearing 10a.

According to this modification, the same effect as that of the above-described embodiment of the present invention can be obtained.

(2) Structure in which a step portion is provided FIG. 5 is a partially enlarged view showing the detailed structure near the upper portion of the upper bearing 10a according to this modification.
It is a figure equivalent to FIG.

In FIG. 5, in this modified example, a stepped portion 11 is provided at the upper corner of the shaft 3 side (inner peripheral side) of the bearing cover 11 instead of the tapered portion 11a of the embodiment of the present invention.
c is provided. At this time, similarly to the above, the outer diameter D2 of the step portion is D1 <D2 so that it is at least larger than the inner diameter D1 of the pump casing 2 above the upper bearing 10a.

Also according to this modification, the same effect as that of the above-described embodiment of the present invention can be obtained.

(3) Structure in which the thickness of the bearing cover is reduced FIG. 6 is a partially enlarged view showing the detailed structure near the upper portion of the upper bearing 10a according to this modification.
It is a figure corresponding to FIG. 4 etc.

In FIG. 6, in this modified example, instead of providing the tapered portion 11a on the bearing cover 11 as in the embodiment of the present invention, the thickness of the bearing cover 11 (dimensions in the axial direction and the height direction). By making the portion itself thinner than the conventional structure (or the gap between the bearing cover 11 and the pump casing 2 may be enlarged without reducing the thickness of the bearing cover 11), this portion is enlarged in the flow passage area enlarged portion C. It is what

According to this modification, the same effect as that of the above-described embodiment of the present invention can be obtained.

(4) Structure in which the through hole is provided in the bearing cover (No. 1) FIG. 7 is a partially enlarged view showing the detailed structure near the upper portion of the upper bearing 10a according to this modification.
It is a figure corresponding to FIG. 4 etc.

In FIG. 7, in this modified example, instead of providing the tapered portion 11a on the bearing cover 11 as in the embodiment of the present invention, a through hole 17 penetrating the bearing cover 11 in the radial direction is formed. 11 are provided at a plurality of positions in the circumferential direction (however, only one position corresponding to the motor cooling water nozzle 14 is shown in FIG. 7 and the others are not shown). It is an enlarged structure.

Also according to this modification, the same effect as that of the above-described embodiment of the present invention can be obtained. Further, in this case, the motor cooling water flow rate can be adjusted by the size of the cross-sectional area of the through hole 17 of the bearing cover 11. If this idea is further applied, the sizes of the through holes 17 provided at a plurality of positions in the circumferential direction may not be the same but may be different. Such a modified example will be described below.

(5) Structure in which the through hole is provided in the bearing cover (No. 1) FIG. 8 is a horizontal sectional view showing a detailed structure near the upper portion of the upper bearing 10a according to this modification.
It is a figure equivalent to the sectional view by the -Y cross section.

In FIG. 8, this modification is based on the above (4).
As in the modified example, through holes 17 that penetrate the bearing cover 11 in the radial direction are provided at a plurality of circumferential positions of the bearing cover 11 (six locations in this example), and the sizes of the through holes 17 are set at the respective positions. And a plurality of types are set according to the distance between the motor cooling water nozzle 14 and the motor cooling water nozzle 14. Specifically, the cross-sectional area A1, so that the cross-sectional area of the through hole 17 increases as the distance from the motor cooling water nozzle 14 increases.
There are four types of A2, A3, A4 (A1 <A2 <A3 <A4). As a result, as the distance from the motor cooling water nozzle 14 increases, the resistance of the motor cooling water when passing through the through holes 17 can be reduced, so that the motor cooling water flows more uniformly in the circumferential direction. Therefore, the motor cooling water flow rate can be increased more reliably.

At this time, in this modification, a plurality of (six in this example) circumferentially divided structures are usually provided at the positions of the gaps (grooves) t between the respective pieces of the upper bearing 10a. By matching the phase of the through hole 17 provided in the bearing cover 11, the circumferential direction component speed of the motor cooling water is suppressed and a part of the motor cooling water is allowed to enter the through hole 17 with a smaller resistance in the flow passage. Has become. However, it goes without saying that the upper bearing 10a does not have to have a divided structure and does not necessarily have to be in phase with the through hole 17 as long as the above-mentioned effects are obtained.

(6) Structure in which the position of the upper bearing is lowered FIG. 9 is a partially enlarged view showing the detailed structure near the upper part of the upper bearing 10a according to this modification.
It is a figure corresponding to FIG. 4 etc.

In FIG. 9, in this modified example, instead of providing the tapered portion 11a on the bearing cover 11 as in the embodiment of the present invention, the bearing housing 13 is used.
By lowering the position of the engaging portion 13b with the upper bearing 10a, the position of the upper end of the upper bearing 10a in the height direction is lowered below the position of the cooling water nozzle 14 in the height direction. The flow path area enlarged portion E is formed in the. Along with this, the bearing cover 11 has a structure in which the motor cooling water flow passage groove 12 is not formed.

According to this modification, as shown by the arrow in FIG. 9, the motor cooling water has a relatively straight path without going around the motor cooling water passage groove 12 as in the embodiment of the present invention. Can reach the cooling water nozzle 14.
Therefore, according to this modification, the same effect as that of the above-described embodiment of the present invention can be obtained.

(7) Structure in which the flow guiding means for changing the direction of the flow of the cooling water is provided FIG. 10 is a partially enlarged view showing the detailed structure near the upper portion of the upper bearing 10a according to this modification, and FIG. 5 is a view corresponding to FIG. 4 and the like.

In FIG. 10, instead of providing the tapered portion 11a on the bearing cover 11 as in the above-described embodiment of the present invention, in this modified example, the upper end portion of the upper bearing sleeve 9a (in other words, the first flow path portion) is provided. At the top of 101)
A flow guiding means 19 such as a guide ring (or a guide vane) for guiding the flow of the cooling water from the axially upward direction to the radially outward direction is provided.

According to this modification, as shown by the arrow in FIG. 10, the upper bearing sleeve 9a and the upper bearing 10a are provided.
Of the motor cooling water that has passed through the gap (= the first flow path portion 101) gradually decreases in the axially upward velocity component in the vicinity of the inner peripheral side corner D of the bearing cover 11, and in the radial outward direction. Is smoothly guided to increase. In this way, when the direction of flow of the motor cooling water is changed (= turned) near the corner D of the bearing cover, the motor cooling water passes through this portion with a resistance in the flow passage smaller than that of the conventional structure, and reaches the motor cooling water nozzle 14. Be guided.

According to this modification, the same effect as that of the above-described embodiment of the present invention can be obtained.

[0061]

According to the invention described in claim 1, the nozzle portion
Is provided at a position higher than the third flow passage of the pump casing
At the same time, since the flow passage area enlarged portion having a larger flow passage area than the upstream side is formed from the downstream side portion of the first flow passage portion to the upstream side portion of the second flow passage portion, when the motor cooling water passes through. The resistance in the flow passage can be reduced, the motor cooling water can be made to flow smoothly, and the pressure loss can be reduced. Thus, it is possible to increase the motor cooling water flow rate, cooling water
Can be made uniform, and the motor cooling performance can be improved without increasing the size of the equipment. Contract
According to the invention described in claim 2, the bearing cover
Install the outer diameter D2 into the pump casing located above the upper bearing means.
Since it is larger than the inner diameter D1 of the housing,
The motor cooling water flowing through the
Smoother while suppressing the flow into the area on the inner peripheral side of D1
Therefore, it can be flowed through the second flow path portion. According to the invention of claim 6 , the nozzle portion is provided with the third flow path of the pump casing.
Since it is provided at a position higher than the upper part, and a flow guide means for guiding the flow of the cooling water from the axially upward direction to the radially outward direction is provided at the upper end portion of the first flow path portion, the diameter between the upper bearing means and the shaft is increased. The motor cooling water that has flowed through the first flow path portion in the directional gap can be smoothly flowed to the radially outer second flow path portion. Therefore, the resistance in the passage when the motor cooling water passes can be reduced to reduce the pressure loss, and the motor cooling water flow rate can be increased. Therefore,
The flow distribution of the cooling water can be made uniform, and the motor cooling performance can be improved without increasing the size of the equipment.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an overall schematic structure of an internal pump according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view showing a detailed structure of an X part in FIG.

FIG. 3 is a motor characteristic diagram for explaining an increase in motor cooling water flow rate according to an embodiment of the present invention, in which the horizontal axis represents the motor cooling water flow rate, and the vertical axis represents the total head of the auxiliary impeller and motor cooling. The pressure loss of the water system (cooling water flow path) is shown.

FIG. 4 is a partially enlarged view showing a detailed structure near an upper portion of an upper bearing according to a modified example in which a rounded portion is provided at an upper corner portion of a shaft of a bearing cover.

FIG. 5 is a partially enlarged view showing a detailed structure near an upper portion of an upper bearing according to a modified example in which a step portion is provided at an upper corner portion of a shaft of a bearing cover.

FIG. 6 is a partially enlarged view showing a detailed structure in the vicinity of an upper portion of an upper bearing according to a modified example in which a bearing cover is made thinner than that of a conventional structure to make this portion a flow passage area enlarged portion.

FIG. 7 is a top view of a modification in which cooling water flow passage areas are enlarged by providing through holes radially passing through the bearing cover at a plurality of circumferential positions of the bearing cover and forming bypass passages for the motor cooling water flow passages. It is a partial enlarged view showing the detailed structure of the upper part of a bearing.

FIG. 8 is a view showing that through holes that penetrate the bearing cover in the radial direction are provided at a plurality of positions in the circumferential direction of the bearing cover,
It is a horizontal cross-sectional view showing the detailed structure near the upper part of the upper bearing according to a modification in which the sizes of the through holes are set to a plurality of types according to the respective positions and the distance between the motor cooling water nozzle.

FIG. 9 lowers the position of the engaging portion of the bearing housing with the upper bearing to lower the height position of the upper end of the upper bearing below the height position of the cooling water nozzle, thereby lowering the upper bearing. FIG. 9 is a partial enlarged view showing a detailed structure near an upper portion of an upper bearing according to a modified example in which a channel area enlarged portion is formed above.

FIG. 10 shows a detailed structure near an upper portion of an upper bearing according to a modified example in which a flow guide means such as a guide ring for guiding the flow of cooling water from an axially upward direction to a radially outward direction is provided at an upper end portion of the upper bearing sleeve. FIG.

[Explanation of symbols]

2 Pump casing 3 shafts 10a upper bearing 11 Bearing cover 11a taper part 11b Rounded part 11c step 13 Bearing housing 14 Motor cooling water nozzle 17 Bearing cover through hole 19 Information ring A, C flow path area expansion part

Front page continuation (72) Inventor Jun Kikushima 603 Jinritsucho, Tsuchiura City, Ibaraki Prefecture Industrial Machinery Systems Division, Hitachi, Ltd. (56) References JP-A-11-326576 (JP, A) JP-A-2000-120594 (JP, A) JP-A-2002-71872 (JP, A) JP-A-2000-338287 (JP, A) ) JP 2000-162361 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G21C 15/243 510 F04D 29/58 G21D 1/04 GDC

Claims (6)

(57) [Claims] 1. A pump casing installed at the bottom of a reactor pressure vessel, a shaft penetrating the reactor pressure vessel inside the pump casing, and an impeller fixed to the shaft inside the reactor pressure vessel. A wet motor unit installed outside the reactor pressure vessel for rotating the shaft; and upper and lower bearing means respectively provided above and below the wet motor unit. An outer peripheral side of the shaft is supported through a radial gap, an outer peripheral side of the upper bearing means is supported by a bearing housing provided on an inner peripheral side of the pump casing, and a bearing cover is provided on an upper portion of the upper bearing means, The cooling water sent to the wet motor section is cooled by the auxiliary impeller installed at the bottom of the wet motor. A first flow passage part formed by the radial gap between the bearing means and the shaft, a second flow passage part formed by the gap between the bearing cover and the pump casing, and the bearing housing in the radial direction. Through the cooling water flow path including the third flow path part provided by
In an internal pump that guides to a nozzle part provided in the pump casing and circulates from the nozzle part to a heat exchanger provided outside the pump casing, the nozzle part is the third flow path part of the pump casing.
In addition to being provided at a higher position, a flow passage area enlarging portion having a flow passage area larger than the upstream side is provided from the downstream side portion of the first flow passage portion to the upstream side portion of the second flow passage portion. Characteristic internal pump. 2. A pump casing installed at the bottom of the reactor pressure vessel.
And the reactor pressure inside the pump casing.
The shaft that penetrates the force vessel and inside the reactor pressure vessel
An impeller fixed to the shaft, and the reactor pressure
Wet installed outside the container to rotate the shaft
Installed above and below the motor part and the wet motor part, respectively.
And upper and lower bearing means that are worn, and
The upper bearing means is arranged on the outer peripheral side of the shaft in the radial direction.
Support through the gap, Outer peripheral side
The bearing housing provided on the inner peripheral side of the pump casing.
Support with a housing and place a bearing on top of the upper bearing means.
Provided with an aligning cover and installed under the wet motor
It is sent to the wet motor part with the auxiliary impeller
Cooling water to the upper bearing means and the shaft.
Between the first flow path portion and the bearing
The gap between the casing cover and the pump casing.
The second flow path portion and the bearing housing in the radial direction
Through a cooling water flow path including a third flow path portion penetrating the
Guide it to the nozzle provided on the pump casing and
From the trickle to the heat exchanger provided outside the pump casing.
In the circulating internal pump, The nozzle part is the third flow path part of the pump casing.
In addition to being installed at a higher position, From the downstream side portion of the first flow path portion to the upstream side of the third flow path portion
A flow path area expansion part is provided between the side parts, Set the outer diameter D2 of the bearing cover to the upper bearing
Than the inner diameter D1 of the pump casing at the top of the
An internal pump characterized by being enlarged. 3. The internal pump of claim 1 or 2, wherein the inner peripheral side corner portion of the bearing cover, the tapered portion, rounded portion, and by providing at least one of the stepped portion, the flow path An internal pump having an enlarged area. 4. The internal pump according to claim 1, wherein the flow passage area enlarged portion is formed by providing a through hole that penetrates the bearing cover in a radial direction. 5. The internal pump according to claim 4 , wherein a plurality of the through holes are provided in the circumferential direction of the bearing cover, and the sizes of the through holes are set at respective positions and the nozzle portion. An internal pump characterized by being set to multiple types according to the distance from. 6. A pump casing installed at the bottom of the reactor pressure vessel, a shaft penetrating the reactor pressure vessel inside the pump casing, and an impeller fixed to the shaft in the reactor pressure vessel. A wet motor unit that is installed outside the reactor pressure vessel to rotate the shaft; and upper and lower bearing means provided above and below the wet motor unit, and the upper bearing unit has an outer circumference of the shaft. Side is supported through a radial gap, the outer peripheral side of the upper bearing means is supported by a bearing housing provided on the inner peripheral side of the pump casing, a bearing cover is provided on the upper part of the upper bearing means, and the wet motor lower part is provided. The cooling water sent to the wet motor section with the auxiliary impeller installed in
The first flow passage portion formed by the radial gap between the upper bearing means and the shaft, the second flow passage portion formed by the gap between the bearing cover and the pump casing, and the bearing housing in the radial direction. An internal pump that leads to a nozzle part provided in the pump casing through a cooling water flow path including a third flow path part that penetrates through and is circulated from the nozzle part to a heat exchanger provided outside the pump casing. In the above, the nozzle portion is connected to the third flow passage portion of the pump casing.
An internal pump, which is provided at a higher position, and at the upper end portion of the first flow path portion , is provided with a flow guide means for guiding a flow of cooling water from an axially upward direction to a radially outward direction.