Abstract:
A filtration and float apparatus and method are disclosed, wherein an integrated float frame and filter is provided, a buoyancy of the float frame and filter causing a sealing of the filtration and float apparatus with a pump.

Description:
FIELD OF THE INVENTION 
     The invention relates to a pump component and more particularly to an integrated float frame and filter apparatus and method of filtration of a molten metal flowing through an electromagnetic pump. 
     BACKGROUND OF THE INVENTION 
     Electromagnetic pumps are designed principally for use in liquid-metal-cooled reactor plants where liquid lithium, sodium, potassium, or sodium-potassium alloys are pumped. However, other metallic and nonmetallic liquids of sufficiently high electrical conductivity, such as mercury, molten aluminum, lead, and bismuth, may also be pumped in non-nuclear applications. The absence of moving parts within the electromagnetic pump eliminates the need for seals and bearings found in conventional mechanical pumps, thus militating against leaks, requiring less maintenance and repairs, and improving pump reliability. 
     An electromagnetic pump operates on the principle that the high electrical conductivity of the liquid metals being pumped allows a pumping force to be developed within the metals when the metals are confined in a duct or channel and subjected to a magnetic field and to an electric current. The duct or channel carrying the liquid metal is placed in the magnetic field and the electric current is passed transversely through the liquid metal so that the liquid metal is subjected to an electromagnetic force in the direction of the flow. 
     In a typical process involving molten aluminum, a float frame and a filter are floated on a molten aluminum bath in a furnace. An inlet of the pump is positioned adjacent the float frame and filter, and the pump and float frame are submerged in the aluminum bath. The buoyancy of the float frame holds the float frame against the pump inlet. As the molten aluminum is pumped, the filter removes impurities in the molten aluminum. Over time and through extensive use, the thermal effects of the molten aluminum on the float frame cause the float frame to crack. When the float frame breaks into several pieces, the float frame is unable to provide adequate buoyancy to maintain contact with the inlet and the filter will sink to the bottom of the molten aluminum bath in the furnace. When the filter is at the bottom of the furnace, it does not filter the molten aluminum and cannot be easily retrieved. 
     It would be desirable to develop a filtration and float apparatus and method, wherein the float frame and the filter remain buoyant when damage to the float frame occurs. 
     SUMMARY OF THE INVENTION 
     Concordant and congruous with the present invention, a filtration and float apparatus and method, wherein the float frame and the filter remain buoyant when damage to the float frame occurs, has surprisingly been discovered. 
     In one embodiment, the pump filter comprises a buoyant float frame having a central aperture formed therein, said float frame having a sealing surface formed thereon adapted for sealing engagement with an inlet of a pump; and a filter disposed in the aperture of said float frame adapted to filter impurities from a fluid flowing to the inlet of the pump. 
     In another embodiment, the filter for an electromagnetic pump comprises a buoyant float frame having a central aperture formed therein, said float frame having a sealing surface formed thereon adapted for sealing engagement with an inlet of the pump, wherein the buoyant float frame is formed using a molding process; and a filter disposed in the aperture of said float frame adapted to filter impurities from a fluid flowing to the inlet of the pump. 
     The invention also provides a method of filtering a molten metal comprising the steps of providing a buoyant float frame having a central aperture formed therein, said float frame having a sealing surface formed thereon adapted for sealing engagement with an inlet of a pump; providing a filter disposed in the aperture of said float frame adapted to filter impurities from a fluid flowing to the inlet of the pump; providing a pump; positioning the float frame adjacent an inlet of the pump; submerging the pump and float frame in a molten metal bath, wherein the float frame sealingly engages the pump due to the buoyancy of the float frame. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which: 
         FIG. 1  is a sectional view of the float apparatus of  FIG. 2  taken along line  1 - 1 ; 
         FIG. 2  is a top plan view of a float apparatus according to an embodiment of the invention; and 
         FIG. 3  is a side elevational view of the float apparatus of  FIGS. 1 and 2  and an electromagnetic pump disposed in a molten metal bath. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following detailed description and appended drawings describe and illustrate various exemplary embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. In respect of the methods disclosed, the steps presented are exemplary in nature, and thus, the order of the steps is not necessary or critical. 
       FIG. 1  shows a float apparatus  10  according to an embodiment of the invention. The float apparatus  10  includes a float frame  12  and a filter  14 . The float frame  12  has a substantially rectangular shape and a central aperture  15 . It is understood that the float frame  12  may have other shapes as desired such as circular, ovoid, triangular, or other shape, for example. As illustrated in  FIG. 2 , the float frame  12  has a first surface  16 , a second surface  18 , a groove  20 , a sealing surface  22 , and four flanges  24  extending from the first surface  16  adjacent the sealing surface  22 . The outer free edges  26  of the flanges  24  have chamfers  28  formed thereon. It is understood that the outer free edges  26  can be any shape such as substantially square or rounded, for example. As shown in  FIGS. 1-3 , an inner surface  29  of each of the flanges  24  is inwardly angled from the chamfer  28  formed on the outer free edge  26  thereof to the sealing surface  22  of the float frame  12 . The groove  20  is formed intermediate the first surface  16  and the second surface  18  on an inner surface  30  of the float frame  12 . The groove  20  is adapted to receive an outer peripheral edge  32  of the filter  14 . The sealing surface  22  surrounds the aperture  15 . In the embodiment shown, the float frame  12  is formed from a silica based material having a chemical composition of: 68.4% SiO 2 , 23.1% Al 2 O 3 , 4.5% CaO, 2.9% ZnO, 1.1% other material. However, it is understood that other silica based materials may be used as well as other conventional materials such as refractory ceramics, and other cement-like materials, for example. 
     The outer peripheral edge  32  of the filter  14  is disposed in the groove  20  of the float frame  12 . It is understood that the filter  14  can be joined to the float frame  12  by any conventional means as desired. The shape of the filter  14  conforms generally to the shape of the float frame  12 , although it is understood that different shapes can be used. In the embodiment shown, the filter  14  is a fused silicone carbide (SiC) particle filter. However, it is understood that any conventional filters can be used, as desired. 
     In the embodiment shown, the filter  14  and the float frame  12  are formed by disposing the filter  14  in a mold (not shown) during a cast molding operation of the float frame  12 . The outer peripheral edge  32  of the filter  14  is disposed in the portion of the mold that forms the groove  20  of the float frame  12 . The material forming the float frame  12  is disposed into the mold. When the material forming the float frame  12  reaches a desired hardened state, the outer peripheral edge  32  of the filter  14  is held in position in the groove  20  of the float frame  12 . It is understood that the material forming the float frame  12  may adhere to the outer peripheral edge  32  of the filter  14 . It is further understood that the filter  14  may be disposed in the groove  20  and coupled to the float frame  12  with a conventional fastener means (not shown) such as an adhesive or bolt, for example. It also understood that other mounting structures such as a lip or mounting brackets can be used, as desired. 
     In use, as shown in  FIG. 3 , the float apparatus  10  is positioned adjacent an inlet  34  of a pump  36 . The float apparatus  10  positioned such that the flanges  24  of the float apparatus  10  abut an outer wall  38  of the inlet  34  and the sealing surface  22  abuts an outer free edge  40  of the inlet  34 . The chamfers  28  and the inner surfaces  29  of the flanges  24  are adapted to guide the pump  36  into sealing engagement with the float apparatus  10 . In the embodiment shown, the pump  36  is an electromagnetic pump. It is understood that the pump  36  may be any conventional pump, as desired. When the float apparatus  10  is in a sealing position, the pump  36  and float apparatus  10  are placed in a fluid bath  42  in a furnace (not shown). The second surface  18  of the float apparatus  10  is the first portion of the float apparatus  10  to contact the fluid bath  42 . The pump  36  and float apparatus  10  are then submerged in the fluid bath  42 . The buoyancy of the material used to form the float frame  12  of the float apparatus  10  causes the sealing surface  22  of the float apparatus  10  to sealingly engage the inlet  34  of the pump  36  and militate against leakage. The combination of the buoyant force generated by the float being submerged in a fluid  44  in the fluid bath  42  against the float frame  12  and the flanges  24  abutting the outer wall  38  of the inlet  34  hold the float apparatus  10  against the inlet  34 . 
     The pump  36  is operated, and the fluid  44  in the fluid bath  42  is caused to flow through the filter  14  of the float apparatus  10 . Particulate and other impurities are removed from the fluid  44  as the fluid  44  flows through the filter  14 . The fluid  44  then flows through the pump  36  to a conduit (not shown) to be utilized in a downstream operation. In the embodiment shown the fluid  44  in the fluid bath  42  is molten aluminum. It is understood that the fluid  44  may be mercury, lead, bismuth, or other molten material, as desired. It is further understood that the fluid bath  42  may be liquid salts used for nuclear and applications, as desired. 
     From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions.