US3859008A

US3859008A - Pump with offset inflow and discharge chambers

Info

Publication number: US3859008A
Application number: US262315A
Authority: US
Inventors: Rudolf Wieser
Original assignee: Andritz AG
Current assignee: Andritz AG
Priority date: 1971-07-06
Filing date: 1972-06-13
Publication date: 1975-01-07
Anticipated expiration: 1992-01-07
Also published as: DE2231128A1; ES403795A1; IT960937B; FR2145350A5; CH541079A; GB1400761A

Abstract

This invention relates to an improvement in a pump for high operating pressures, particularly a main coolant pump for pressurized water or boiling water reactors comprising a pressure housing, a vertical pump shaft having an impeller thereon, a distributor surrounding the impeller, and suction and discharge connections, the pump shaft having an axis normal to the axis of the suction and the discharge connections. The improvement comprises a separator plate having an opening therein and dividing the pressure housing into a lower section constituting an inflow chamber and an upper section constituting a discharge chamber, the upper section containing the impeller and the distributor, and the inflow chamber and the discharge chamber constituting rotational chambers which are mechanically machined.

Description

United States Patent Wieser Jan. 7, 1975 PUMP WITH OFFSET INFLOW AND DISCHARGE CHAMBERS [75] Inventor: Rudolf Wieser, Voitsberg, Austria 22 Filed: June13, 1972 21 Appl. No.: 262,315

[30] Foreign Application Priority Data July 6, 1971 Austria 5846/71 [52] U.S. Cl 415/219, 415/217, 415/208 [51] Int. Cl. F04d 29/40, F04d 29/46, F04d 29/54 [58] Field of Search 415/210, 219 R, 77,185, 415/196, 182, 184, 189; 417/424 [56] References Cited UNITED STATES PATENTS 678,199 7/1901 Richards 415/210 1,476,210 12/1923 Moody 415/184 1,704,375 3/1929 Taylor 415/189 2,933,045 4/1960 lsserlis 415/183 2,949,859 8/1960 Granberg 415/210 3,421,446 l/1969 Strscheletzly 415/182 FOREIGN PATENTS OR APPLICATIONS 1,237,144 3/1959 France 417/424 180,823 6/1922 Great Britain 415/182 Primary ExaminerCarlton R. Croyle Assistant Examiner-Louis T. Casaregola Attorney, Agent, or Firm-James E. Bryan [57] ABSTRACT This invention relates to an improvement in a pump for high operating pressures, particularly a main coolant pump for pressurized water or boiling water reactors comprising a pressure housing, a vertical pump shaft having an impeller thereon, a distributor sur' rounding the impeller, and suction and discharge connections, the pump shaft having an axis normal to the axis of the suction and the discharge connections. The improvement comprises a separator plate having an opening therein and dividing the pressure housing into a lower section constituting an inflow chamber and an upper section constituting a discharge chamber, the upper section containing the impeller and the distributor, and the inflow chamber and the discharge chamber constituting rotational chambers which are mechanically machined.

2 Claims, 12 Drawing Figures PAIENIEB W 3,859,008

saw an:

PUMP WITH OFFSET INFLOW AND DISCHARGE CHAMBERS The present invention relates to a pump designed for high operating pressures, particularly a main coolant pump for pressurized water reactors or boiling water reactors.

The following disclosure is directed to main coolant pumps for pressurized water reactors, but it applies analogously also to pumps for boiling water reactors.

It is the function of the main coolant pumps of pressurized water reactors to circulate the heat carrier, usually light water, but sometimes also heavy water, through the reactor and the steam generator. The temperature of the heat carrier is approximately 270280 C. at the reactor outlet. In the steam generator the heat carrier is re-eooled, at which time steam is produced which is passed to the turbine.

The main coolant pumps are interposed between the steam generator and the reactor, viewed in the direction of flow. They are exposed to the operating pressure of the reactor circulation of approximately 120 160 atmospheres. The pressure increase which the pump produces in order to overcome the circulation resistances amount, on the other hand, only to about atmospheres. The pump is therefore designed in a single stage.

Depending upon the extent of the capacity of the atomic power station (which is currently between 300 and 1,200 MWe), two, three, or four main coolant pumps per reactor are provided. The main coolant pumps have discharge or delivery quantities of from approximately l0,000 to 25,000 m h, a power input of from approximately 5,000 to 12,000 kW, and suction connections or inlets and pressure connections or outlets with an inside diameter of approximately 600 to 800 millimeters.

For safety reasons, the reactor together with the heat generators and main coolant pumps is accommodated within a containment which consists of an inner steel ball and a surrounding concrete enclosure. The diameter of the steel ball amounts to approximately 50 meters. The steel ball must be designed and provided for an internal pressure of approximately 4 atmospheres and therefore has a wall thickness of from 30 to 40 millimeters.

In order to reduce the containment and thereby reduce costs, one requirement which has been raised, inter alia, in connection with main coolant pumps is that the vertical distance between the pump pressure connection or outlet and the horizontal axis of the pump suction line be as small as possible. An additional requirement is the simplification of the extension of the pump pressure line and the pump suction line (for example, omission of line elbows) in order to thereby decrease the quantity of water in the reactor circulation because it influences the volume of the containment. A large quantity of water in the reactor circulation necessitates, of course, a greater volume of the containment,

In the main coolant pumps of conventional construction which have cylindrical or spherical housings, the axis of the pressure connection is horizontally downwardly directed; the axis of the suction connection is vertically downwardly directed. These main coolant pumps require therefore a feed or inlet elbow on the suction side. The pump suction line which extends from the steam generator to the pump is positioned, for this reason, more deeply within the containment than the housing of the main coolant pump. The vertical distance between the horizontal axis of the pump pressure connection and the horizontal axis of the pump suction line therefore amounts to about 3 meters in the main coolant pumps having the conventional construction. Furthermore, in these pumps, the pump suction line requires a further elbow at the steam generator since the position in the vertical sense of the steam generator coincides approximately with that of the main coolant pump and the pump suction line must initially extend downwardly from the steam generator.

in order to allow for a further reduction in size of the containment of a pressurized water reactor and for a decrease of the quantity of water in the reactor circulation, the present invention proposes a main coolant pump wherein one inflow chamber and one discharge chamber are arranged in juxtaposition, preferably superimposed within a common cylinder-like or spherically shaped pressure housing, and are separated from each other by a separator or baffle plate. The suction connection of the pump has a horizontal, or an approximately horizontal, axis and terminates in the inflow chamber. The pressure connection of the pump branches off of the discharge chamber and equally has a horizontal, or an approximately horizontal, axis. The vertical distance of the two axes is small, for example smaller than 500 millimeters, and even may be equal to zero.

The novel main coolant pump may have impellers and guide wheels having an axial, semi-axial, or radial configuration.

The separator or baffle plate in the pump housing is provided with an opening that is coaxial with the shaft axis; this opening establishes the connection between the inflow chamber and the discharge chamber and is enclosed with a reinforcing beading, the latter serving also for the meridian guidance of the fluid.

Disposed on the separator or baffle plate is a suction pipe which projects into the inflow chamber and may be extracted therefrom preferably upwardly, and which comprises at the lower end thereof a divided deflecting beading. Additionally positioned on the separator or baffle plate, if necessary, is a diffuser pipe which projects into the discharge chamber and is longitudi nally divided for purposes of the introduction thereof.

When the novel main coolant pump has an axial configuration of the impellers and guide wheels, the impeller and the guide blades are disposed in the lower area of the diffuse pipe above the suction pipe. In case of a semi-axial or radial configuration and construction, the impeller is disposed above the suction pipe, and the divided guide blades are disposed below the flange of the pump housing.

The inflow chamber and the discharge chamber are provided as rotational chambers so that the inner surfaces thereof may be machined mechanically. Only the transition surfaces and the inner surfaces of the housing connections must be ground manually. in order to render possible an easier machining of the inflow chamber, a treating or machining opening which is closed off by a lid may be provided in the bottom of the pump housmg.

In order to reduce the inflow losses of the flow medium into the inflow chamber, which may be achieved by an increase of the cross-sectional inlet area, the axis of the inflow chamber is displaced from the shaft axis towards the suction connection. Analogously, for the purpose of reducing the discharge losses, the axis of the discharge chamber is displaced from the shaft axis toward the pressure connection.

In order to achieve a further reduction of the inflow losses, a plowshare-like inflow shield or plate is so disposed within the inflow chamber at the suction pipe opposite the suction connection that its edge points toward the connection opening. Further disposed in the inflow chamber on the side opposite the suction connection is a steering or guide body or element whose guiding surfaces are shaped in such a manner that they deflect the water to the lower opening of the suction pipe with as few losses as possible. This guiding body or element must be divided for reasons pertaining to the assembly thereof. The guiding body or element may be so provided that it can be machined largely mechanically.

Disposed within the suction pipe and arranged coaxially with respect thereto is a deflecting mushroom which is secured to the bottom of the pump housing and, respectively, to the lid of the treating opening. This deflecting obturator head or mushroom together with the suction pipe conveys the water to the impeller in a genuinely accelerated flow.

Since the pump housing consists of cast steel, whereas the connecting lines from the steam generator and to the reactor are rolled, forged transition rings must be provided at the housing connections. For the purpose of obtaining an additional decrease of the inflow and discharge losses of the pump, the present invention proposes that the transition rings be conical, and specifically with an optimal angle of approximately 6 with respect to the axis. These conical transition rings act as a diffuser at the suction connection, and as a nozzle at the pressure connection.

It is also possible, however, to provide longer suction and pressure connections at the housing which then will be arranged in the outer sections thereof as a diffuser and as a nozzle, respectively, with an optimal angle of inclination.

For the purpose of improving the flow conditions in the discharge chamber, a deflecting shield or plate which has a wedge-shaped cross-section and whose edge points upwardly is provided on the side opposite the pressure connection. Also provided directly ahead of the pressure connection is a discharge shield or plate which has a plowshare-like configuration and whose edge points toward the connection opening.

In order to render the quantity of water in the pump as small as possible, all of the steering or guiding elements (the inflow shield, guiding body or element, deflecting obturator or mushroom, deflecting shield, and discharge shield) are provided as solid bodies.

The main coolant pump of the present invention has additional advantages, and specifically in the following cases:

In order to reduce the costs of constructing pressurized water nuclear power stations, and in order to further increase the output of the power station up to 2,000 MW, there exist tendencies to increase the maximal output of the main coolant pump from about 25,000 m /h obtained at present to about 50,000 m lh.

These high-efficiency coolant pumps would have very large connection cross-sections if the present flow velocities in the pump connections of from 10-14 m/s were maintained. Accordingly, the connecting openings of the primary lines at the reactor pressure vessel would likewise be very large so that such vessels hardly could be manufactured.

On the other hand, if the present dimensions of the pressure connections were maintained with the water velocities changed to up to 25 m/s, the specific power requirements of the pump would increase by about percent. This would result in a considerable increase of the internal consumption of the power station, which is most undesirable.

In order to make it possible, however, to keep the connecting openings of the primary pipes at the reactor at their present size and nevertheless be able to construct high-efficiency main coolant pumps with the present specific power requirement (in other words, with the present flow velocities), it is proposed according to the present invention that the novel main coolant pump be built with two pressure connections and that two pressure lines extend therefrom toward the reac' tor.

In the novel pump, seen in a cross-sectional view thereof, the two pressure connections may be brought together up to a sector angle of about 60, which is very favorable for the extension of the two pressure lines to the reactor, since only a few pipe elbows are required in this case.

Also the sector angle between the suction connection and the adjacent pressure connection can be brought to a minimal value of about 60, seen in the crosssectional view of the pump.

7 If it is intended that a high-efficiency or largecapacity main coolant pump suctions from two steam generators, two suction connections also may be provided for in an advantageous manner.

The novel main coolant pump has a still further advantage 7 It is possible to install within one and the same pressure housing pumps for an entire discharge or delivery range, for example from 18,000 to 25,000 m h unless the operating pressure of the pump should vary more markedly. In this case, the impeller and guide wheels may be dimensioned in an optimum manner for l the respectively envisaged discharge or delivery be cause impellers and guide wheels with different diameters may be built into one and the same housing.

It is further possible to accommodate within one and the same pressure housing impellers for different pressure heads.

Two embodiments of the present invention and a number of details thereof are illustrated by way of example in the accompanying drawings, wherein FIG. 1 is a longitudinal cross-sectional view through a pump with a cylinder-type housing and an axial impeller and guide wheel, in which the axes of the suction and of the pressure connections are positioned in a straight line;

FIG. 2 illustrates the suction connection of the pump with a welded-on transition ring 20;

FIG. 3 illustrates the pressure connection with the aforementioned conical transition ring;

FIG. 4 is a cross-sectional view through the deflecting shield, taken along line IV-IV of FIG. 1;

FIG. 5 is a cross-sectional view through the discharge shield, taken along line V-V of FIG. 1;

FIG. 6 is a cross-sectional view through the inflow shield, taken along line VI-VI of FIG. I; the directions of flow having been shown in FIGS. 4 through 6;

FIG. 7 illustrates a modified embodiment of a pump with a semi-axial impeller and radial distributor as well as a spherical-type housing, wherein the reference numerals have the same meaning as in FIGS. 1 through 6;

FIG. 8 illustrates the guiding body or element in an axonometric representation and shown from below, the two guiding surfaces being indicated by cross-hatching;

FIGS. 9 through 11 are cross-sectional views taken on line A-A of FIG. 1 through pump housings with one or two longitudinal connections and, respectively, one or two pressure connections, whose axes enclose acute angles with each other, and

FIG. 12 is a view in elevation of a steam generator with main coolant pump and the pump suction line connecting the former, being shown in phantom in the old, bent form thereof, and in solid lines in the novel, straight form thereof.

In the embodiment according to FIG. 1, an inflow chamber 2 is disposed in the housing and thereabove the discharge chamber 3; these chambers are separated from each other by means of the separator or baffle plate 4. The suction connection 5 terminates in the inflow chamber; the pressure connection 6 branches off the discharge chamber.

The axes a b of the inflow chamber 2 is displaced or shifted from the shaft axis toward the suction connection 5. The axis c d of the discharge chamber 3 is displaced or shifted from the shaft axis toward the pressure connection 6. The separator or baffle plate 4 is connected with the pump housing 1 by means of large, rounded-out radii 7 which serve for the meridian deflection of the flow medium. The separator or baffle plate 4 has an opening 8 which is surrounded by a reinforcing beading 9.

Downwardly secured to the separator plate 4 is the suction pipe 10 which carries at one end thereof a divided deflecting beading 11. Further disposed on the separator plate 4 but upwardly is a diffuser pipe 12 which is longitudinally divided.

The impeller 13 and the distributor 14 are arranged above the suction pipe 10; they may be extracted or removed from the pump housing 1 jointly with the pump lid and the interposed upper pump portion. The lower part of the distributor 14 is provided with sealing rings 14a and is enclosed with the reinforcing beading 9 of the separator plate 4.

Disposed within the inflow chamber 2 are the inflow shield or plate 15 (see FIG. 6), the divided guiding body or element 16, and the deflecting obturator head or mushroom 17.

Disposed within the discharge chamber 3 are the defleeting shield or plate 18 (see FIG. 4) and the discharge shield or plate 19 (see FIG. 5).

In the modified embodiment according to FIG. 7, a sealing ring 21 is provided between the divided distributor 14b and the suction pipe 10. Provided in the bottom of the pump housing 1 is a treating opening which is closed off by means of a lid 22, the latter being supported from the inside of the housing 1 against the flange of the opening.

FIG. 8 illustrates the steering or guiding body or element used in the embodiments of FIGS. 1 and 7 in an axonometric view from below; the guiding surfaces being cross-hatched extend upwardly to the upper horizontal plane of the guiding body or element.

In the (horizontal) normal axial cross-section of a pump housing according to FIG. 9, the axes of the suction and of the

pressure connections

5 and 6 enclose with each other an acute angle a. The positions of the inflow shield 15, the deflecting shield 18, and the dis charge shield 19 with respect to the

pump connections

5 and 6 also have been shown in this figure.

Apparent from the normal axial cross-sectional view through the housing of a high-efficiency main coolant pump according to FIG. 10 are a larger suction connection 5 and two smaller pressure connections 6. The axes of the pressure connections 6 enclose or form the acute angle [3 with each other. Provided therein are an inflow shield 15, two deflecting shields 18 and two dis charge shields 19. The two deflecting shields 18 are disposed in the plane of symmetry of the two pressure connections 6.

The normal axial cross-sectional view of FIG. 11 shows a high-efficiency main coolant pump with two suction connections 5 and two pressure connections 6. The position of the

shields

15, 18, and 19 is also shown therein.

Apparent from the illustration of FIG. 12 is the omission of two elbows of the pump suction line between the steam generator 23 and the pump.

By virtue of the present invention it is possible to make pumps in which the axes of the suction and of the pressure connection are positioned in a straight line. Such pumps may be installed in a straight line, in a manner similar to valve housings; they do not therefore need any elbows. Pumps of this construction also may be employed for other purposes, for example for feeding petroleum in pipelines, or as circulating pumps in La-Mont boilers.

It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

What is claimed is:

1. In a pump for high operating pressures, particularly a main coolant pump for pressurized water or boiling water reactors, comprising a pressure housing, a vertical pump shaft having an impeller thereon, a distributor surrounding the impeller, and suction and dis charge connections, said pump shaft having an axis normal to the axis of said suction and discharge connections,

the improvement comprising separator plate means having an opening therein and dividing said pressure housing into a lower section constituting an inflow chamber means and an upper section constituting a discharge chamber means, said upper sec tion containing said impeller and distributor,

and the axis of said inflow chamber means being displaced from the pump shaft axis toward the suction side.

2. In a pump for high operating pressures, particularly a main coolant pump for pressurized water or boil ing water reactors, comprising a pressure housing, a vertical pump shaft having an impeller thereon, a distributor surrounding the impeller, and suction and discharge connections, said pump shaft having an axis normal to the axis of said suction and discharge connections,

the improvement comprising separator plate means ,having an opening therein and dividing said pres sure housing into a lower section constituting an inflow chamber means and an upper section constituting a discharge chamber means, said upper section containing said impeller and distributor,

and the axis of said discharge chamber means being displaced from the pump shaft axis toward the pressure side.

Claims

1. In a pump for high operating pressures, particularly a main coolant pump for pressurized water or boiling water reactors, comprising a pressure housing, a vertical pump shaft having an impeller thereon, a distributor surrounding the impeller, and suction and discharge connections, said pump shaft having an axis normal to the axis of said suction and discharge connections, the improvement comprising separator plate means having an opening therein and dividing said pressure housing into a lower section constituting an inflow chamber means and an upper section constituting a discharge chamber means, said upper section containing said impeller and distributor, and the axis of said inflow chamber means being displaced from the pump shaft axis toward the suction side.

2. In a pump for high operating pressures, particularly a main coolant pump for pressurized water or boiling water reactors, comprising a pressure housing, a vertical pump shaft having an impeller thereon, a distributor surrounding the impeller, and suction and discharge connections, said pump shaft having an axis normal to the axis of said suction and discharge connections, the improvement comprising separator plate means having an opening therein and dividing said pressure housing into a lower section constituting an inflow chamber means and an upper section constituting a discharge chamber means, said upper section containing said impeller and distributor, and the axis of said discharge chamber means being displaced from the pump shaft axis toward the pressure side.