US3088411A

US3088411A - Pump

Info

Publication number: US3088411A
Application number: US754238A
Authority: US
Inventors: Schmidt Ernst Heinrich Wilhelm
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-08-12
Filing date: 1958-08-11
Publication date: 1963-05-07
Anticipated expiration: 1980-05-07

Description

SEAC

SR Cg EFEENCE KR 5 88q4 FIFEESQZ May 7, 1963 E. H. w. SCHMIDT PUMP Filed Aug. 11, 1958 ates Uite The present invention relates to pumps.

More particularly, the present invention relates to a pump as well as to a pumping method for moving conductive liquids, particularly liquid metals, with help of a magnetic field and a direct current traversing the liquid substantially perpendicularly to each other and to the direction of the flow of the liquid.

The simplest way of doing this is to use a constant magnetic field and a direct current. For this purpose, low-voltage and high-amperage current is necessary, and to this end specially constructed machinery is required, such as DC. generators or arrangements in which A.C. or three-phase is applied together with a synchronized magnetic field of the same frequency.

Such electrodynamic pumps are used especially for pumping liquid metals needed for cooling as well as for transporting heat in nuclear reactors. As these pumps and the liquids transported thereby usually become radioactive under the influence of the radiation of the reactor, they are not accessible for a long period of time. Therefore, the reliability of the entire installation must be very high, and this, in turn, requires expensive machinery. Further difficulties arise when liquid sodium or liquid po tassium is to be handled.

It is, therefore, an object of the present invention to overcome the above disadvantage, and, with this object in view, the present invention consists mainly in a method and apparatus for pumping conductive liquids, especially liquid metals, in which the direct current is produced thermoelectrically. To this end, two thermocouple elements of different thermoelectrical properties are brought into good electric contact at one of their ends, whereas their free ends are electrically connected by the liquid to be transported. If the liquid has a temperature different from that of the junction of the thermocouple elements, a direct current of suflicient amperage is produced to move the liquid metal under the influence of the electric field.

The invention will be better understood by the following detailed description thereof, when read in conjunction with the accompanying drawing in which:

FIGS. 1 to 4 show four embodiments of a pump according to the present invention.

FIG. illustrates a specific conduit structure usable in connection with pumps according to the present invention.

Referring now to the drawing, and to FIG. 1 thereof in particular, there is shown a pump which includes a duct or conduit means 1 which is preferably of substantially rectangular cross-section, through which conduit means the conductive liquid is to be transported in the direction of arrows 14. The conduit means are made of a metal of low electric conductivity, such as constantan, and are arranged between the spaced.

poles

2 and 3 of a suitable magnet means, which derives its energy from a source other than the direct current produced by the thermoelectric means described below, in such a way that the lines of magnetic flux of the magnetic field generated by the magnet means pass through the conduit means in a direction substantially perpendicular to the direction of flow of the liquid.

According to the present invention, the current through the conduit means are produced by thermoelectric means, and the latter include two

thermocouple elements

5 and 6.

The element 5, which is in the form of a substantially flat plate, is also made of constantan, and is at one of its ends soldered or otherwise electrically connected to the conduit means 1 at one of its narrow sides 4. The other element 6, which is made of copper, is soldered to the other end of the element 5 as indicated at 7. This element 6 is in the form of a yoke or stirrup which is insulated from the element 5 and conduit means 1 by a thin layer of air 15, and passes through the magnetic field to the opposite narrow side 8 of the conduit means 1. Thus, the liquid in the conduit means 1 closes the electric circuit between the

thermoelements

5 and 6. It is true, of course, that since the conduit means 1 are made of metal, some of the electric current will flow through the wide side walls. This amount, however, is relatively small in comparison to the current flowing through the liquid which is not only usually a better conductor of electricity than constantan, but which also otfers a substantially greater cross-section to the current flow than do the wide side walls of the conduit means 1. Yet, even this slight inefficiency may be avoided by making the conduit means of insulating material, such as a ceramic material of sufficient heat resistance, in which case suitable means are provided for placing the

thermocouple elements

5 and 6 in electrical connection with the liquid in the conduit means. This may be accomplished by introducing leads into the interior of the conduit means through openings or recesses. Alternatively, a metallic conductor may be diffused into the narrow walls of the conduit means, in a manner well known in the art.

Such a conduit means 1 is shown in FIG. 5. It is made of electrically insulating material with the exception of two

places

18 and 19 shaded in the figure, on opposite sides of the conduit means, where the thermoelectrical current enters and leaves the liquid metal. In these areas the wall is made electrically conducting for instance by replacing the insulating material of the wall by a sheet of metal or by any other means. If the conduit means is made of ceramic material, it can be made electrically conducting by adding metallic powder to the ceramic material before burning. To these electrically conducting parts the two metals of the thermocouple have to be joined conventionally for instance by soldering.

If a sufficiently great difference in temperature is produced between the

connections

7 and 8, then a thermoelectric current will flow through the liquid and cause the latter to move in the direction of the arrows 14. Suitable means, therefore, are provided for maintaining the junction of the

elements

5 and 6 at a temperature different from that of the liquid flowing through the conduit means. In the embodiment shown in FIG. 1, the temperature is maintained lower by circulating a coolant, such as water, through a cooling conduit 16 which is in good heat exchange relation with the juncture 7 of the

elements

5 and 6.

FIG. 2 shows a pump similar to that of FIG. 1 except that the thermocouple element 6 has an additional yoke portion 6, and the two yoke portions are arranged symmetrically with respect to the conduit means 1 in that they pass through the magnetic field above and below the conduit means. While this arrangement increases the distance between the

magnetic poles

2 and 3 and consequently reduces the magnetic induction in the liquid to a certain extent, the magnetic field generated by the thermoelectric current is compensated.

The arrangement according to FIG. 2 further differs from that shown in FIG. 1 in that insulating sheets 9 are interposed between the yoke portions 6, 6' and the element 5 and the conduit means 1, and that instead of a cooling means, a heating means, for instance, in the form of a hot liquid in duct 17, is provided for maintaining the junction 7 of the thermocouple elements at a temperature higher than that of the liquid in duct 1.

FIG. 3 shows an embodiment of a pump according to the present invention in which high efiiciency is obtained by avoiding loss of magnetic induction due to relatively great separation of the

poles

2 and 3. This is achieved by passing one of the .thermocouple elements directly through the poles of the magnet means. Thus, the element is constituted by a number of separate portions 11 which pass through a corresponding number of

openings

10, 10 of the upper pole 2. In the illustrated embodiment, the openings 10 are in the form of slots and the opening 10" is in the form of a cut-out. Alternatively, the thermocouple element may consist of a single yoke, as in the case of FIG. 1, and the pole may be formed with a single slit or cut-out sufficiently large to permit the yoke to pass therethrough.

FIG. 4 illustrates another embodiment of the present invention wherein the

poles

2 and 3 are as near to each other as possible. This construction is made possible by fashioning one of the thermocouple elements as a yoke which comprises

end portions

12, 12a and bridge portions 13 which straddle the pole 2. As may readily be seen from the drawing, the end portion 12 is in contact with the thermocouple element at 7, whereas the end portion 12a is in contact with the conduit means 1. In this way, as in the case of the arrangement shown in FIG. 3, the gap between the

poles

2 and 3 need be no greater than the thickness of the conduit means 1.

The drawings may represent the pump according to the invention in natural size (scale 1:1). However, the dimensions may also be substantially smaller or bigger.

The Voltage of the thermoelectric current depends upon the material of the thermocouple, for which the combination constantan, copper is only an example. Using a liquid metal, such as mercury, of about 500 C. and a coolant of 30 C., the voltage produced by a constantan, copper thermoelernent, may be of the order of magnitude of to 20 millivolt.

The amperage produced by this voltage depends essentially upon the dimensions of the whole circuit and the specific resistances of its components. It may be of the order of magnitude of some 20 up to several thousands of amperes if the strength of the magnetic field is in the order of magnitude of 1020,000 gauss.

The speed of the liquid depends upon the resistance of the conduit means which it has to pass on its way. In practical embodiments it may be of the order of magnitude of some centimeters up to some meters per second.

It will be understood that the present invention is susceptible to modification in order to adapt it to difierent usages and conditions, and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

What I claim is:

1. A pump for pumping electrically conducting liquids, especially liquid metals, comprising, in combination, conduit means through which the liquid having a temperature diflerent than an ambient temperature may flow; a first thermoelectric element; a second thermoelectric element, dissimilar from said first one, said two elements being connected to said conduit means and forming a first junction which includes said liquid as electrical connection in between, said two elements being further connected remote from said first junction so as to form a second junction in heat conductive relationship with said ambient temperature, said two elements constituting thermoelectric means for passing a direct current through the liquid in said conduit means at said first junction in a direction substantially perpendicular to said conduit means; and magnet means for generating a magnetic field the magnetic lines of flux of which pass through said conduit means in a direction substantially perpendicular thereto as well as substantially perpendicular to the direction in which said direct current is passed through said conduit means, said magnet means deriving its energy from a source other than the direct current produced by said thermoelectric means.

2. A pump as defined in claim 1 wherein said thermoelectric means further include means for maintaining the junction of said elements at a temperature different from that of the liquid flowing through said conduit means.

3. A pump as defined in claim 1 wherein said thermoelectric means further include means for maintaining the junction of said elements at a temperature higher than that of the liquid flowing through said conduit means. i 4. A pump as defined in claim 1 wherein said thermoelectric means further include means for maintaining the junction of said elements at a temperature lower than that of the liquid flowing through said conduit means.

5. A pump as defined in claim 1 wherein said conduit means are made of the same material as one of said thermocouple elements.

6. A pump as defined in claim 1 wherein said conduit means are made of insulating material and wherein means are provided placing said thermocouple elements in electrical connection with the liquid in said conduit means.

7. A pump as defined in claim 1 wherein said conduit means are of substantially rectangular cross-section.

8. A pump as defined in claim 1 wherein said magnet means comprise two spaced poles between which said conduit means extend.

9. A pump as defined in claim 8 wherein one of said thermocouple elements extends between said poles of said magnet means.

10. A pump as defined in claim 8 wherein one of said thermocouple elements extends between said poles of said magnet means and is arranged symmetrically with respect to said conduit means.

11. A pump as defined in claim 8 wherein one of said thermocouple elements passes through said magnet means.

12. A pump as defined in claim 8 wherein one of said thermocouple elements comprises bridge portions straddling said magnet means.

13. A pump as defined in claim 1 wherein one of said thermocouple elements is in the form of substantially fiat plate.

References Cited in the file of this patent UNITED STATES PATENTS 330,451 Weston Nov. 17, 1885 2,031,967 Mathias Feb. 25, 1936 2,686,474 Pulley Aug. 17, 1954 2,715,686 Asti Aug. 16, 1955 2,748,710 Vandenberg June 5, 1956 2,798,434 Brill et al. July 9, 1957 2,919,356 Fry Dec. 29, 1959 2,962,718 Hilgert Nov. 29, 1960 2,977,050 Sparrow Mar. 28, 1961

Claims

1. A PUMP FOR PUMPING ELECTRICALLY CONDUCTING LIQUIDS, ESPECIALLY LIQUID METALS, COMPRISING, IN COMBINATION, CONDUIT MEANS THROUGH WHICH THE LIQUID HAVING A TEMPERATURE DIFFERENT THAN AN AMBIENT TEMPERATURE MAY FLOW; A FIRST THERMOELECTRIC ELEMENT; A SECOND THERMOELECTRIC ELEMENT, DISSIMILIAR FROM SAID FIRST ONE, SAID TWO ELEMENTS BEING CONNECTED TO SAID CONDUIT MEANS FORMING A FIRST JUNCTION WHICH INCLUDES SAID LIQUID AS ELECTRICAL CONNECTION IN BETWEEN, SAID TWO ELEMENTS BEING FURTHER CONNECTED REMOTE FROM SAID FIRST JUNCTION SO AS TO FORM A SECOND JUNCTION IN HEAT CONDUCTIVE RELATIONSHIP WITH SAID AMBIENT TEMPERATURE, SAID TWO ELEMENTS CONSTITUTING THERMOELECTRIC MEANS FOR PASSING A DIRECT CURRENT THROUGH THE LIQUID IN SAID CONDUIT MEANS AT SAID FIRST JUNCTION IN A DIRECTION SUBSTANTIALLY PERPENDICULAR TO SAID CONDUIT MEANS; AND MAGNET MEANS FOR GENERATING A MAGNETIC FIELD THE MAGNETIC LINES OF FLUX OF WHICH PASS THROUGH SAID CONDUIT MEANS IN DIRECTION SUBSTANTIALLY PERPENDICULAR THERETO AS WELL AS SUBSTANTIALLY PEREPNDICULAR TO THE DIRECTION IN WHICH SAID DIRECT CURRENT IS PASSED THROUGH SAID CONDUIT MEANS, SAID MAGNET MEANS DERIVING ITS ENERGY FROM A SOURCE OTHER THAN THE DIRECT CURRENT PRODUCED BY SAID THERMOELECTRIC MEANS.