US2644073A - Dielectric heating with rotatory work-receiving element - Google Patents

Description

P D NEWHOUSE 2,644,073

DIELECTRIC HEATING WITH ROTATORY WORK-RECEIVING ELEMENT Filed April 1, 1949 INVENTOR .PAUL D. NEWHOUSE.

2 Sheets-Sheet 1 ATTORNEY June 30, 1953 WITNESSES:

Patented June 30, 1953 UNITED STATES PATENT OFFICE DIELECTRIC-HEATING WITH ROTATORY" WORK-RECEIVING ELEMENT Paul D". Newhous'e; Salix, Iowa, assignorto'West inghouse Electric Corporation, East Pittsburgh; Pa.,. a corporation of Pennsylvania Application Aprilil, 1949, Serial No. 84381.

3 Claims:

Broadly; my invention relates to-means' for the invention, the work or material is carried inside a rotatory element through a radial high-frequency field produced bystationary electrodes that have no physical contact with the rotatory element. of eliminating the need for sliding orrolling contacts, brushes etc., whichcausearcing-and energy losses, and are otherwise troublesome;

A general object'ofmy'invention isto provide a means of a type; described for the; dielectric heating, for any purpose; of*'non-gaseous fiuidic' material; and a particular-"object in this connection is toaccomplish such heating on a continuous mass-production basis;

A further object of my invention is to provide a dielectric heatingsystem of a type: described in which a radially-extending electric field is provided at the inner surface of a rotating tubularmember or container bymeans ofan inner electrode on'the inside of the tubular member or container, the" electrode" being insulated. there.- from.

Another obj ect of my invention is" to' provide a dielectric heating system of atype' described in which the radial field is established by-a stationary electrode inside a work-receiving container, and another stationaryelectrode'outside of the container. The container has a wall whicheholds the work to'be heated, and all'or a portion'of this wall moves'betweenthe two stationary electrodes as it-rotates.v The container isof metal, and is capacitively coupled to the outer electrode forfeeding electrical energy into the work. tubewhich completely surrounds the container and by grounding this outerielectrode, a high degree of safety for operatorsofthe-apparatus is obtained.

Objects, features and innovations of my invention, in addition to the foregoing, will. be. discernible from the following description of several preferred forms thereof. to betaken in conjunction with theaccompanying'drawings in which details not essential toan Such a structure has the advantage- By making the. outer electrode a This description is understanding oftheinventionhave beenomitted in the interests of simplicity and clarity; In" the simplified drawings, which are not to scale, Figure 1 is a vertical axial sectional viewofan embodiment of my'invention;

Figs. 2' and 3' are sectional views alongthe lines II'II and III--III,' respectively, of Fig. 1;

Fig. 4 is a vertical sectional view; corresponding to Fig. 2', of another embodiment of myinvention;

Fig. 5 is a vertical'sectlonal view'ofa further embodiment of 'my' invention;

Fig. 6 is a; horizontalse'ctional view on the'lin'e VI--VI of Fig. 5; and

Figs; 7' and 8 are: partial vertical sections of further modifications of my invention;

The broader aspects of" mybinvention can find expression in many difierentembodiments, each constituting a newand useful improvement inits' In this application, my invention is own right.

shown in severalforms. One comprises a rotary kiln comprising a tubular member throughwhich discrete solid particles are passed for dielectric heat-treatment. of a drying centrifuge. Still another form of my invention which utilizes rollers between which sheet material moves; is describedand claimed in my copending' application'Serial'No. 84,882; filed concurrently herewith.-

Figs. 1 through-4 show myinvention' embodied in a rotarykiln=type apparatus. Work or mat'erial 2 'in' the form ofdiscreteparticles such'a's', byway of exampleon'ly; grain'particles', is slow 1y fed from a hopper its the upper'open end'of arotatory work receiving' member or tumbler having a wall in the form of a tube or'tubula'r' member 6' of metal. The other end of tumbler tubular member Bhas an insulating plate Ssesupporting means comprisesa shaft'l2 secured to the-center ofthe insulating plate 8 and a bearing or bearings. It for the shaft. The'shaft l2 isrotatedby anysuitabledriving means; The tumbler tubular member 6S constitutes a Workreceiving container and has a helicallwork-guide E6, of exceptionally low-loss insulation," secured' to its inner surface for assuring downward movement of particles of material 2 fed to the member $5 from the hopper '4. Similarly, spaced insulating longitudinal tumbling strips I! can be.

secured to the insideof the tumblenbetween'th'e turns of the work=guide l6; Material passing A further'form is inthe'nature' aeaaovs through the tubular member 6 discharges therefrom through openings ill and falls into any suitable work-receiving means it.

A high-frequency electric field is established through the work-carrying portion along the lower side of the tumbler tubular member 6, through means comprising an inner electrode 22 and outer electrode 2 The inner electrode comprises a curved metal plate 2t carried by an insulating support 28 that includes a rod 29 that passes through the upper open end of the tumbler tubular member 5. This rod may be fastened to any suitable structure that holds the support 253 and the electrode stationary inside the tumbler tubular member so that the curved plate of the electrode 22 is spaced from the tumbler tubular member 5. By stationary, I do not mean absolutely fixed with respect to the ground, since I contemplate adjustably positioning the plate inside the tumbler tubular n1ember at different distances from the tumbler tubular and either substantially conor coat al therewith or with its axis at an angle therewith.

The outer electrode it also comprises a curved member in the form of a stationary metal that completely encompasses the tumbler 1 rneznber This tube Eli] is also concentric the tubular member 8. The nested room h s, comprising the inner plate lit, the outer e -lll and the intermediate tubular member electrically insulated from each other, and to give any suitable spacing between them.

he upper part or the inner electrode 22 can 'ovided with a pair of insulating boards W or proper length to form a tent or dihedral angle over the hollow portion of the curved 3 so as to prevent that ride :p the tubular member 6 from falling into the hollow portion of the curved plate of the electrode Highrequency energy is supplied to the electrodes 22 and Ed by any suitable means. For ex ample, it may be applied. by means of a transmission linecomprising a coaxial cable having an outer grounded conductor it and an inner insulate-d conductor 3. The insulated conductor is directly electrically connected to the insulated metal plate of the inner electrode 22. grounded conductor is electrically con nected to the tube SE of the outer electrode 2 5, either directly or through ground, the tube being shown grounded at A tube-oscillation gen erator (not shown) can be connected, through any suitable control apparatus, to the coaxial cable as a source for the high-frequency energy, which for dielectric heating usually has a frequency in the order of inegacycles. The outer electrode capacitively coupled to the tuinbler tubular n oer through the air space between them.

'en the electrodes 22 and M are energized, li ireauency voltage exists across them and an electric hold is provided that passes radially through that lower portion of the tumbler tubular znei'nber El which happens to be between the facing parts of the plate and tube of theelectrodes. The radial electric field thus provided dielectrically heat-treats particles of material they move downwardly during the rotation of the tumbler tubular member 6.

An important feature of my invention resides in the fact that no direct electrical connection is required between the tumbler tubular member s and either of the electrodes 22 and 24 in order to establish a radial field inside of the tubular member, that passes through the lower workcarrying portion thereof. Also, by grounding the 5 tube til of the outer electrode 24 and by having it substantially completely encompass the turnbier tubular member 6, the high-potential parts of the dielectric heating apparatus described are well screened, and a high degree of safety is assured for operators around the apparatus.

Fig. i represents a modified form of apparatus which corresponds substantially to that described in connection with Figs. 1. through 3, except that the inner electrode is made in the form of a com" plete metal tube 4:2 instead of a partly cylindrical metal plate, such as plate Such construction will provide a complete radial electric field around the full inside surface of the tumbler tubular member Fig. 5 shows a drying centrifuge embodying the principles of invention. Referring to this figure, the rotatory work-receiving tubular member coin rises a pair of nested or concentric rents or walls 52 and that are ride a work-receiving space in which non-gaseous fiuidic work or material 56, such for silica gel to be dried, or cloth material to be dried, is received. An annular bottom. lid of nsulation closes the space between the inner tubular element 552 and the outer tubu" lar ele .cn; is carried on insulating disc is which is ro tatably carried on a hollow shaft 52 journalled in a bear or bearings When the hollow shaft ted, it is evident that the ubular mernb s also rotate at a speed depending on the rotational or the shaft The shaft be driven at desired speed by any .ble means.

. space of the tubular i on ved. el ctrodes E8 and the former being inside the r and the latter outside of it. The inc-er and outer curved electrodes 58 and respect ly can be supported in any suitable manner so as to be concentric with but sta tionary with respect to the rotatory tubular member The support trode cor.

v means shown for the inner elecprises a stationary shaft that passes upwacuy through the hollow rotatable shaft i'he shaft extends upwardly beyond. the insulating disc carries eross-bars l2 which, in turn, carry the inner electrode 66 which is in the form of a tube is but obviously can be some other shape. The outer electrode 68 is in the fOllll of a metal tube 35 that is car-- For supplying high-irevoltage across electrodes {36 and 68, nsinission line is connected to the electrodes, insulated conductor i362 detachably se inner electrode rat, and grounded conductor i i electrically co;..nected to the tube of tr e outer electrode it through a suitable connection, shown as a ground connection 85.

The rotator tubular member to constitutes a work-receiving container or cage which is the only rotating or" the apparatus except for the driving shaft and the supporting means from. the shaft to the tubular member. The highvoltage electrode lit on the inside of the container is practically entirely surrounded by material o Wu.

5 being processed and by the grounded outer electrode 68.

The tubular elements or walls 52 and 54 of the tubular member 59 can be constructed in any desired manner suited to the purpose to which my invention is applied, which may be drying, centrifugal separation, or any other purpose for which centrifuges or rotatory tubular members are commonly used. An apparatus of the type shown is especially suited for treating viscous materials, such as, for example, oil from which Water is to be removed, etc. The viscosity of highly viscous materials is reduced with heat, and vapors are driven off which can be removed by an air blast 68 which blows air upwardly through the space between the outer tube 76 and the outer tubular element 54 of the rotatory tubular member 56. To permit this use of the apparatus, the inner tubular element 52 can be made from sheet metal, and outer tubular element 5d can be made from a metal screen or perforated sheet metal that allows easy passage or liquid or vapor. If desired, the outer tubular member 76 of the outer electrode 69 can also be made from metal screening or the equivalent. Copper or aluminum is recommended for the metal parts of the apparatus, unless either reacts with the material being processed. In such case, any other suitable low conductivity metal or plated metal can be used. Obviously, for heating liquids the two tubular elements 52 and 54 of the tubular member or container 50 should be solid.

In order to permit the container to be easily loaded and unloaded, the insulation disc 69 that supports the tubular member 59 can be provided with an annular seat 99 in which the tubular member removably sits so that the member can be lifted out of the apparatus whenever desired, and then restored.

For best electrical eiiiciency, the voltage across the space or spaces between the stationary and rotating parts should be as low as possible so that most of the voltage supplied by the generator appears across the material being heated. Figs. 7 and 8 show improved means for raising the proportion of voltage across the useful load with respect to the voltage required for the capacitive coupling.

In Fig. 7, the rotating insulating disc I00 carries a work-holding tubular member 192 com.- prising a metal outer tube 16:1 and a metal inner tube I96. The stationary parts comprise an outer set of concentric metal tubes Hi3 and I I0, which are grounded, and an inner set of concentric metal tubes i I2, 5 E i and I Hi which are connected to an insulated high-voltage high-frequency conductor H3.

Unitary with and electrically connected to the outer tube I64 of the work-holding member I02 is a metal tube I22. The tube I22 is concentric with the tubes 108 and H0 and rotates between them. Similarly, the inner tube I96 of the workholding member 2 t2 is provided with nested metal tubes 12d and [26 to which it is electrically connected. The tubes i241 and 126 rotate between the tubes H2, H6 and [16.

In cases where it is not necessary to remove the work-holding container from the disc, the capacitiv coupling for providing a voltage across the inner and outer tubes of the rotating container can be arranged as shown in 8. In Fig. 8, the stationary electrodes I39 and I32 are provided with annular plates 16 and 836 which interleave similar plates 138 and M0 on a rotating work-holding container :42.

While I have described my invention in forms which are now preferred, it is obvious that its principles can be applied in other forms and modifications.

I claim as my invention:

1. Dielectric heating means of a type described comprising, in combination, a pair of spaceyl, upstanding substantially-coaxial, stationary, relatively-insulated, metallic curved electrode-members, an annular-like container substantially coaxial with said electrode-members comprising a plurality of wall members, said-container being positioned between said electrode-members, support means for rotatably supporting said container between said electrode-members and insulated therefrom, and means for applying a high-frequency voltage across said electrodemembers.

2. An invention including that of claim 1, but further characterized by said container comprising a pair of nested upstanding walls, adapted to contain a non-gaseous fiuidic material, that pass between said electrode-members as the container is rotated.

3. An invention including that of claim 1, but further characterized by said container being removable from between said electrode-members.

PAUL D. NEWI-IOUSE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,954,273 Subkow Sept. 15, 1936 2,167,718 Harris Aug. 1, 1939 2,231,457 Stephen Feb. 11, 1941 2,403,800 Hoyler July 9, 1946 2,472,193 Clayton June 7, 1949 2,473,881 Hagopian June 21, 1949 2,479,351 Hagopian Aug. 16, 1949 2,501,776 Kuljian Mar. 28, 1950 2,512,604 Bierwirth June 27, 1950 FOREIGN PATENTS Number Country Date 609,192 Great Britain Sept. 27, 1943 986,860 France Aug. 6, 1951 517,798 Great Britain Feb. 8, 1940

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