US2119297A - Electrical precipitation - Google Patents

Description

May 31, 1938. L N, C TT 2,119,297

ELECTRICAL PRECIPITATION Filed April 4, 1956 4 Sheets-Sheet l gwucm/bou May 31, 1938. L. N. SCOTT I ELECTRICAL PRECIPITATION Filed April 4, 1936 4 Sheets-Sheet 2 May 31, 1938. L. N. SCOTT ELECTRICAL PRECIPITATION Filed April 4, 1936' 4 Sheets-Sheet 3 all!!! May 31, L. SCOTT 2,119,297

ELECTRICAL PRECIPI'TATI ON Filed April 4, 1936 4 Sheets-Sheet 4 and, May 31, 1938 PATENT" OFFICE ELECTRICAL PRECIPITATION Lloyd N. scan, New York, n. Y., assignmto la.

search Corporation, ration of New York New York, N. Y., a' corpo- Application April 4,1936, Serial No. 12,829

22 Claims.

This invention relates to a method and apparatus for the removal of suspended particles from gases by the action of an electrical field, particularly by subjecting gases containing suspended particles to the action of an electric field maintained between attenuated discharge electrodes and collecting electrodes of relativelyfextended surface. A principal object oi. the invention is the provision of a method and apparatus wherein motion of the gas being treated relative to the electrode members is controlled in direction and amount to increase the efficiency of the electrical precipitation.

A further object is to provide a method and apparatus wherein centrifugal force operates to facilitate the precipitation of the suspended particles from the gases.

Another object is to provide a method and apparatus wherein the removal of precipitated particles from the electrodes into receiving means is facilitated by centrifugal force.

Another object of the invention is the provision of a method and apparatus wherein the forces acting on the gases and the suspended particles are controlled so as to cooperate in the effective separation of the suspended particles.

The method of the invention comprises subiecting gases containing suspended particles to the action of a moving system of complementary electrodes while the velocity and direction of flow of the gases are regulated to facilitate the precipitation of the suspended particles, for err--v ample, by maintaining the gas relatively quies- 35 cent with respect to the electrodes during the electrical precipitation operation.

The invention will be more particularly described with reference to the accompanying drawings showing illustrative embodiments of the in- 40 vention.

In the drawings;

Fig. l is a side elevation, Fig. 2 is a plan view, and Fig. 3 is a side elevation in partial section on line 3-4! of Fig. 2 of one embodiment of the in- 45 vention;

Fig. 4 is an elevation in partial section and Fig. 5 is a section on line 5-5 of Fig. 4 of another embodiment of the invention;

Fig. 6 is a sectional elevation, and Fig. '7 is 50 a section on line i-l of Fig. 6, of a further embodiment of the invention;

Fig. 8 is an elevation in partial section of another embodiment of the invention; and

Fig. 9 is a fragmentary plan in partial section 55 of the rotating electrode system of Fig. 8.

In the apparatus shown in Figs. 1, 2 and 3, II is the shell of the precipitator, I2 is the gas inlet conduit and I3 is the gas outlet conduit. [4 is the receiving hopper for precipitated materials. Mounted on shaft passing longitudinally through the shell ii are radial collecting electrode members I5 which are fastened to circular and members ii. Electrode members It and end members ii fit in a substantially gas-tight manner against shell ii and divide the interior of the shell intoa plurality of separate radial compartments id.

In each compartment is a longitudinal discharge member 19 insulatedly carried in end members ii. The discharge members are connected to a source of high tension, preferably unidirectional, current through conductor ring 20 and conductor M. The other members constituting the apparatus, including collecting electrodes l 6, are grounded.

The complementary electrode system and end members ii! are rotated about the shaft J5 by motor 22 and gearing 23, in the direction indicated by the arrow.

The rawgas entering from conduit l2 comes in contact with directing vanes 24 which guide the flow of gas in the direction of rotation of electrodes it and it. As raw gas enters each treating compartment it displaces an equal amount of treated gas which leaves through conduit IS. The proper regulation of the speed of rotation of the electrode system with respect to the gas pressure in conduit 12 at any desired degree of displacement cf the gas in the compartments can be obtained.

The gas in each compartment is carried around the inside of the treater and while in a quiet state it is subjected to the electrical field between electrodes it and i9 and at the same time the suspended particles are subjected to the centrifugal force arising from the rotation of the compartments. the centrifugal force not only assists in the removal of particles from the gas, but it tends to move accumulations of particles from electrodes it to the inner surface of shell M. It also efiects the removal ofany precipitate that tends to accumulate on the discharge electrodes it and thus keeps the latter free of deposits. The precipitated material collecting on the inner surface of cylinder it is scraped along the surface by the edges of electrodes It and is finally discharged into hopper it through opening 25.

The apparatus of Figs. 4 and 5 includes a vertical cylindrical shell ll provided with a cover 52 having gas outlet openings 43. Gas inlet con- 55 duits 44 open into shell 4|. The flow of gas from conduits 44 may be controlled by gates 45. Concentrically positioned within shell 4| is an inner shell 46' which makes a slip joint at the lower end with annular floor member 41 attached to the lower end of shell 4|.

Dust hoppers 48 open into the interior of the treater through floor 41 and are connected with dust collection recesses 49.

In the annular space between shells 4| and 46 is positioned a rotatable electrode system consisting of a. plurality of radial collecting electrode vanes 50 havingdischarge electrode members 5| positioned therebetween. The collecting electrode vanes 50 are carried on-shell 46 by members 52. The discharge electrodes are supported by members 53 which are carried by shaft 54 mounted on insulator 55. The discharge electrodes are connected with a source of high tension current by conductor 56 passing through insulator bushing 51. The rest of the apparatus, including the collecting electrodes, is grounded. Discharge electrodes 5| are maintained in proper spaced relation by members 58 carried by spacing ring 59. Ring 60 helps to maintain the spacing of collecting electrodes 50. s

The whole moving electrode system is carried on rollers 6| mounted between plates 62 and 63, and. is driven by shaft 64. The rotating system is guided by rollers 65 acting on guide ring 66.

In the operation of this precipitator, treated gas is displaced from the compartments formed by the collecting electrode vanes 50 when the compartments come opposite inlet conduits 44. The treated gas passes out through openings 43, and the raw gas which enters the compartments to a controlled degree is carried around by the rotating vanes to the next inlet opening. During the interval it is subjected, in a relatively quiet condition, to the ioint'action of an electrical field between the discharge and collecting electrodes and the centrifugal force arising from the rotation. These forces tend to cause the suspended matter to collect on the inner surface of shell 4|, from which it is scraped by the edges of vanes 50 to dust recesses 49, where it drops into hoppers 48.

Inner shell 48 and housing 61 serve to protect insulators 55 and 51, respectively, from the action of the gases undergoing treatment. The interior of the shell 48 and housing 61 may advantageously be supplied with slow streams of dried or heated gas. I

In the apparatus shown in Figs. 6 and '7, the precipitator chamber is formed by a vertical cylindrical shell 8|. Rotatably mounted within shell 8| is a concentrically positioned electrode system comprising a plurality of superposed collecting electrode members 82 in the form of inverted pans with slightly conical tops provided with a plurality of apertures I00 and a plurality of discharge electrodes 83 and 83' spaced from the collecting electrodes. The rotating electrode system is carried on and rotated by shaft 84 rotatably supported by member 85 through roller bearings 86. The lower collecting electrode members 82 and the floor member 81 are supported from the top collecting electrode member 89 and positioned by means of supports 88.

The discharge electrodes 83 and 83' are supported and positioned by rods 90 attached to the top collecting electrode member 89 by insulators 9|. The discharge electrode system is supported at the bottom in foot bearing 92, which also serves to connect the discharge electrode syst m w source of high tension current through conductor 93 entering through insulator bushing 94.

The rotating electrode system is further guided at the bottom by means of guide rollers 95 bearing on floor member 81. Fastened to electrode member 89 is annular member 98 making a slip joint with shell 8|. The collecting electrodes and shell are connected to ground.

The raw gas enters the apparatus through inlet conduit 99, which makes a slip joint with floor member 81, and passes vertically upward through the superposed treating zones. By suitably regulating the rate of rotation and the velocity of gas flow any desired degree of treatment in each treating zone may be attained.

The electrostatic precipitation is aided by th" centrifugal force generated by the rotation of the electrode system to cause the suspended particles in the gas to be deposited on the surfaces of the collecting electrodes which are so shaped that the combined influence of gravitational and centrifugal forces keeps the deposited material continually moving outwardly and downwardly into the annular channel IOI between the shell 8| and the collecting electrodes. The material which passes into this channel drops down into the bottom of the shell 8|.

In the apparatus of Figs. 8 and 3, III is a shell with a top member I I2 and a bottom member I I3 mounted on supporting structure H5. Partitions I I4 and H40. divide the interior of the shell into gas outlet header II6, a gas inlet header 1 and a dust collection chamber II 8.

Centrally mounted within shell I is a rotatable electrode system comprising collecting electrodes H9 and I20 and discharge electrodes I2I mounted on a hollow vertical shaft I22 of nonconductive material, such as Bakelite." The collecting electrodes I20are circular rods positioned by vertical members I24 to form a cylindrical cage. This cage is divided into a plurality of radial compartments by substantially U- shaped rod electrodes II9 of approximately hyperbolic form the ends of which are attached to vertical members I24 at the periphery of the cage, while their bases are attached to cylinder I25 which is mounted on hollow shaft I22.

Centrally positioned in each radial compartment is a vertical discharge electrode I2I. The discharge electrodes are supported between an upper plate I26 of conductive material, for example steel, and a lower spider I21 of non-conductive material, such as Bakelite. The discharge electrodes are connected with a source of high tension current through plate I26, upper bearing shaft I28 and conductor I29.

The hollow shaft I22 and electrode system carried thereby are rotated by means of shaft I30 driven through pulley I3I by drive means not shown.

The collecting electrodes are grounded through cylinder I25, bolts I32 and shaft I30.

Raw gas enters the apparatus through inlet opening I32, inlet manifold I33 and guide I34 in inlet header II9. Passing upwards through the rotating electrode system the suspended particles therein are subjected to a combination of electrical and centrifugal forces which carry the suspended material into dust collection chamber II8 from which it drops into dust hoppers I35. The treated gas passes into outlet header H6 and out through outlets I36.

The rotation of the electrode system greatly improves the efilciency of the removal of suspended particles not only because of the centrifugal. force thereby generated which keeps the electrodes free of dust and supplements the effect of the electrical forces, but also because of the greatly increased effectiveness of contact of the electrode system with the gas being treated. With six collecting electrode rods M9 in each plane rotating at 500 R. P. M., there are 50 passages of collecting electrode surface past any given point per second. With 14 superposed collecting electrode rods in each vertical foot, each particle of dust would be brought into close proximity to a collecting electrode surface 700 times during a travel of one foot.

It will be notedthat in all of the embodiments of the invention illustrated and described, not only does the centrifugal force generated by the rotation of the electrode system cooperate with and reinforce the action of the electric field in efiecting precipitation of the suspended particles out of the gases being treated, but the centrifugal force is also efiective in effecting the removal of,

the precipitated particles from the electrodes into suitable receiving means whereby it may be efficiently removed from the system.

I claim: I 1. A method of removing suspended materials from gases which comprises subjecting the gases to the action of a rotating electric field maintained between an attenuated electrode and an electrode of extended surface and causing the gas to move in substantial conformity with the motion of said electric field.

2. A method of removing suspended materials from gases which comprises carrying successive isolated portions of the gas in an arcuate path and simultaneously subjecting the gas to the action of a high potential electric field.

3. A method of removing suspended materials from gases which comprises carrying successive isolated portions of the gas in an arcuate path and simultaneously subjecting the gas to the action of a high potential unidirectional electric field.

4. A method of removing suspended materials from gases which comprises carrying successive isolated portions of the gas in an arcuate path at a velocity sumcient to give rise to substantial centrifugal force and simultaneously subjecting the gas to the action of a high potential electric field.

5. A method of removing suspended material from a gas which comprises subjecting successive isolated portions of the gas to the combined action of an electrical field and centrifugal force.

6. A method of removing suspended material from a gas which comprises subjecting successive portions of the gas in a substantially quiescent condition to the combined action of an electrical field and centrifugal force.

7. An apparatus for the electrical treatment of gases comprising means defining a chamber, a plurality of collecting electrode members rotatably mounted in said chamber and positioned to define with the walls said chamber a plurality of compartments radi 1y arranged with respect to the axis of rotation of said collecting electrode members, at least one discharge electrode member positioned in each of said compartments and supported for rotation with said collecting electrode members, and an opening in the wall of said chamber communicating successively with each of said compartments as the said electrode members are rotated.

8. Apparatus for the electrical treatment of gases comprising means defining a chamber, a

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plurality of collecting electrode members rotatably mounted in said chamber and positioned to define with the walls of said chamber a plurality of compartments radially arranged with respect to the axis of rotation of said collecting electrode members, at least one discharge electrode member positioned in each of said compartments and supported for rotation with said collecting electrode members, and an-opening for the introduction of gas in the wall of said chamber communicating successively with each of said compartments as the said electrode members are rotated.

9. Apparatus for the electrical treatment of gases comprising means defining a chamber, a plurality of collecting electrode members rotatably mounted in said chamber and positioned to define with the walls of said chamber a plurality of compartments radially arranged with respect to the axis of rotation of said collecting electrode members, at least one discharge electrode mem- I municating successively with each of said compartments as the, said electrode members are rotated.

10. Apparatus for the electrical treatment of gases comprising means defining a chamber, a plurality of collecting electrode members rotatably mounted in said chamber and'positioned to define with the walls of said chamber a plurality of compartments radially arranged with respect to the axis of rotation of said collecting electrode members, at least one discharge electrode member positioned in each of said compartments and supported for rotation with said collecting'electrode membera'and spaced openings in the wall of said chamber communicating successively with each of said compartments as the said electrode members are rotated.

11. Apparatus for the electrical treatment of gases comprising means defining a chamber, a plurality of collecting electrode members mounted in said chamber for rotation about a horizontal axis and positioned to define with the walls of said chamber a plurality of compartments radially arranged with respect to the axis of rotation of said collecting electrode members, at least one discharge electrode member positioned in each of said compartments and supported for rotation with said collecting electrode members, and an opening in the wall of said chamber communicating successively with each of said compartments as the said electrode members are rotated.

and an opening in the wall of said chamber com municating successively with each of said compartments as the said electrode members are rotated.

13. Apparatus for the electrical treatment of gases comprising a plurality of collecting electrodes mounted for rotation about a common axis and positioned to define a plurality of compartments, at least one discharge electrode member positioned in each of said compartments and supported for rotation with said collecting electrode members, and means for introducing gases successively into each of said compartments.

14. Apparatus for the electrical treatment of gases comprising a plurality of collecting electrodes mounted for rotation about a common axis and positioned to define a plurality of compartments radially arranged with respect to the axis of rotation of said collecting electrode members, at least one discharge electrode member positioned in each of said compartments and supported for rotation with said collecting electrode members, and means for introducing gases successively into each of said compartments.

15. Apparatus for the electrical treatment of gases comprising a plurality of collecting electrodes mounted for rotation about a common axis and positioned to define a plurality of compartments serially arranged along the axis of rotation of said collecting electrode members, at least one discharge electrode member positioned in each of said compartments and supported for rotation with said collecting electrode members, and means for introducing gases successively into each of said compartments.

'16. Apparatus for the electrical treatment of gases comprising a plurality of superposed collecting electrodes mounted for rotation about a common axis and positioned to define a plurality of compartments, at least one discharge electrode member positioned in each of said compartments and supported for rotation with said collecting electrode members, and means for introducing gases successively into each of said compartments.

1'7. A method of removing suspended particles from gases which comprises subjecting the gases to the action of an electrical field between opposed electrodes maintained at a high potential difference, moving the electrodes in fixed spaced relationship, and removing precipitated material from the electrodes by centrifugal force generated by motion of the electrodes.

18. A method of removing suspended particles from gases which comprises subjecting the gases to the action of an electrical field between 'opposed electrodes maintained at a high potential diflerence, rotating the electrodes in fixed spaced relation, and removing precipitated material from the electrodes by centrifugal force generated by rotation of the electrodes.

19. A method of removing suspended material from gases which comprises subjecting the gas to the action of an electrical field between a discharge and a collecting electrode maintained at a high diiference of potential whereby the suspended material is precipitated on the collecting electrode, moving the collecting electrode during the electrical treatment at an angular velocity sufficient to remove the precipitated material by centrifugal force, and collecting the material removed from the electrode by the same centrifugal force.

20. A method of removing suspended particles from gases which comprises subjecting the gases to the action of an electric field established between a discharge electrode and a collecting electrode while rotating the collecting electrode, moving the particles toward the surfaces of the collecting electrode by the action of the electric field and moving the particles from adjacent the collecting electrode surfaces to collecting means by the action of centrifugal force generated by the rotation of the collecting electrode.

21. A method of removing suspended particles from gases which comprises subjecting the gases to the action of an electric field established between a discharge electrode and a collecting electrode while rotating the collecting electrode, agglomerating the particles and moving them toward-the surface of the collecting electrode by the action of the electric field and moving the particles from adjacent the collecting electrode surfaces to collecting means by the action of centrifugal force generated by the rotation of the collecting electrode.

22. A method of removing suspended particles from gases which comprises subjecting the gases to the action of an electric field established between complementary electrodes while in a state of rotation, moving the particles towards a receiving surface of the complementary electrodes by action of the electric field and moving the particles from adjacent the receiving surface to collecting means by the action of centrifugal force generated by the rotation of the complementary electrodes.

LLOYD N. SCO'I'I'.

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