JPH0631635B2 - Internal pump - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an internal pump for circulating a reactor cooling medium.

[Prior Art and its Problems] The internal pump is a pump installed at the bottom of the reactor pressure vessel 1 as shown in FIG. 1, and is an impeller 2, a diff user 3, and a rotor 5 in a motor case 4 in the reactor. , A radial bearing 6, a thrust bearing 7, a motor rotor 8, a motor stator 9 and a mounting nozzle 10 for mounting the motor case to the pressure vessel. In the above configuration, the Diff user 3 is installed such that its geometric center coincides with the geometric center of the mounting nozzle 10 during installation. With such a configuration, according to various experiments and analyzes by the present inventors, the gap between the impeller 2 and the diff user 3 is uniform in the circumferential direction during normal temperature operation as shown in FIG. However, during high temperature rated operation, the mounting nozzle 10 is thermally deformed due to the asymmetry of the mounting nozzle 10, and
As shown in the figure, the gap between the impeller 2 and the diff user 3 becomes non-uniform in the circumferential direction, and the pump performance deteriorates.
In the worst case, the impeller 2 contacts the diff user 3,
It turns out that there is a possibility of destruction.

[Object of the Invention]

The present invention has improved the above-mentioned drawbacks of the internal pump and improved the pump performance by preventing the impeller from contacting the diffuser even at the time of high temperature rated operation of the pump and reducing friction loss of the pump at high temperature rating. The purpose is to provide an internal pump.

[Outline of Invention]

In order to achieve the above-mentioned object, the present invention provides a mounting nozzle provided at a peripheral portion of a bottom peripheral portion inside a pressure vessel of a nuclear reactor, a motor case fixed to the mounting nozzle and provided outside the pressure vessel, and a motor case. A motor stator disposed therein, a motor rotor rotatably supported in the motor case, having one end disposed inside the pressure container through the mounting nozzle, and the pressure mounted at the one end of the motor rotor. An internal pump equipped with an impeller for circulating a cooling medium in a container, and a diffuser arranged around the impeller with a gap and supported by the pressure container, wherein the impeller at high temperature rated operation is used. During installation, the clearance between the diffuser and the diffuser should be more uniform in the circumferential direction than the clearance during installation. It is characterized in that the diffuser is arranged so as to be eccentric by a predetermined amount with respect to the impeller.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, an impeller does not contact a diffuser at the time of high temperature rated operation, and friction loss of a pump is reduced and pump performance can be improved.

Example of Invention

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 shows the case where the Diff user 3 is staggered in the radial direction by e. Here, e is obtained by directly measuring the relative displacement between the diff user 3 and the impeller 2 by the change amount of the gap between the diff user 3 and the impeller 2 when the pump is actually operated in the high temperature rated state as shown in FIG. It may be calculated, or may be calculated analytically by numerical calculation. By installing the diff user as shown in FIG. 3, the gap between the impeller 2 and the diff user 3 becomes uniform in the circumferential direction in the high temperature rated state as shown in FIG. Similarly, when installing the diff user 2, as shown in FIG. 5, the impeller 2 and the diff user 3 are installed.
Even when the apparatus is installed so as to be inclined so that the relative displacement of the variable e changes by e, the gap between the impeller 2 and the diff user 3 becomes uniform during the high temperature rated operation as shown in FIG. From the viewpoint of pump friction loss, the above example is illustrated by a dotted line and the embodiment of the present invention by a solid line as shown in FIG. That is, in the conventional example, the friction loss is small at room temperature, but when the temperature is high, the gap between the impeller and the diff user is reduced, which increases the friction loss. On the other hand, in the present invention, the friction loss is large at room temperature, but at high temperature, the gap becomes uniform, so that the friction loss is reduced. Therefore, during high temperature rated operation, in the case of the present invention, friction loss is reduced and pump performance is improved.

Since the amount of eccentricity is increased at the time of installation, friction loss is large until high temperature rated operation, but this friction loss corresponds to the impeller 2 at the critical rotation speed that the pump passes before reaching steady rotation. Since the effect of suppressing the whirling of the fluid bearing action that occurs in the gap between the diffuser 3 and the diffuser 3 is increased, the safety at the time of passing the critical rotational speed is improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a state of a conventional internal pump at the time of installation, FIG. 2 is a sectional view showing a state of a conventional internal pump at a high temperature rated operation, and FIGS. FIG. 3 and FIG. 4 are cross-sectional views showing the state during installation when the diff user is displaced in the radial direction and during high temperature rated operation, and FIGS. 5 and 6 show the diff user. FIG. 7 is a cross-sectional view showing a state during installation when tilted and during high temperature rated operation, and FIG. 7 is a diagram shown for explaining the characteristics of the present invention. DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel, 2 ... Impeller 3 ... Diff user, 4 ... Motor case 5 ... Rotor, 6 ... Radial bearing 7 ... Thrust bearing, 8 ... Motor rotor 9 ... Motor stator, 10 ... Mounting nozzle

Claims (3)

[Claims] 1. A mounting nozzle provided at a peripheral part of a bottom peripheral portion inside a pressure vessel of a nuclear reactor, a motor case fixed to the mounting nozzle and provided outside the pressure vessel, and a motor arranged in the motor case. A motor rotor rotatably supported in the motor case and penetrating the mounting nozzle and having one end disposed inside the pressure container; and a cooling medium mounted on the one end of the motor rotor and inside the pressure container. In an internal pump equipped with an impeller for circulation and a diffuser supported around the impeller with a gap and supported by the pressure vessel, a gap between the impeller and the diffuser during high temperature rated operation However, in order to improve the uniformity in the circumferential direction compared to the clearance at the time of installation, Internal pump, characterized in that a said diffuser by a predetermined eccentricity. 2. The internal pump according to claim 1, wherein the diffuser is eccentrically arranged by being displaced by a predetermined amount in the radial direction. 3. The internal pump according to claim 1, wherein the diffuser is arranged so as to be inclined by a predetermined amount.