US1349362A

US1349362A - Electrical precipitating system

Info

Publication number: US1349362A
Application number: US140840A
Authority: US
Inventors: Lewis W Chubb
Original assignee: Westinghouse Electric Corp
Current assignee: Westinghouse Electric Corp
Priority date: 1917-01-06
Filing date: 1917-01-06
Publication date: 1920-08-10
Anticipated expiration: 1937-08-10

Description

L. W. CHUBB. ELECTRICAL PRECIPITATING SYSTEM.

APPLICATION FILED JAN. 6, I917.

Patented Aug. '10, 1920.

INVENTOR leg 41s W 6/21/66.

- WITNESSES: 5am.

ATr'ORNEY uurrrzo s'rArss PATENT orrrcs.

LEWIS W. CHUBB, OF EDGEWOOD PARK, PENNSYLVANIA, ASSIGNOR To wEsTmm -HOUSE ELECTRIC 8; MANUFACTURING COMTANY, A CORPORATION OF PENNSYL- VAN IA.

ELECTRICAL PRECIPITATING SYSTEM.

Specification of Letters Patent.

Patented Aug. 10, 1920.

Application filed January 8, 1917. Serial No. 140,940.

To all whom it may concern:

Be itlmown that I, LEWIS W. Cause, .a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Electrical Precipitating Systems, of which the following is a specification.

My invention relates to electrical siystems employed for precipitating finely ivided particles of matter -from bodies of gas or vapor in which they are held in suspension.

For this service, the apparatus employed involves the use of at least two electrodes of opposite polarity, one of them having a relatively small surface from which electrical dischargeseusually in the form of corona emanationsmay take place. This electrode is designated as the discharge electrode. Another electrode of opposite polarity and having a relatively large surface area is designated as the collecting electrode. The collecting electrode or electrodes, as the case may be, are placed in juxtaposition to the discharge electrode. The suspended particles in the vapors or uses undergoing treatment are electrically deposited on these collecting electrodes by reason of the electrical charges imparted to the particles by the discharge electrode.

One of the methods employed in electrical precipitation processes contemplates maintaining a continuous electrical discharge from one of the electrodes whereby the particles to be precipitated are deposited on the other electrode. In this instance, the negative potential is applied, preferably, to the electrode possessing the surface of smaller area from which the corona discharges emanate and it is of such a value as to establish a potential difference betweenthe electrodes that is in excess of that which may be maintained when a positive potential is a plied to said surface. Hence, it follows that the discharge electrode is main tained at a very high electrical potential, preferably negative, in order to produce corona or silent electrical discharges in one direction only.

' In practising my invention I find it particularly advantageous to so position the discharge and collecting electrodes in the treating chamber that active and inactive zones of the electric field, established by the energization of the electrodes, are formed therein. That is, the portion of the interior of the treating chamber in which the discharge and collecting electrodes are directly opposite each other will, of course, be the most actlve electrically, while the zone farthest away from the point of opposition of the electrodes will be substantially in active due to the non-existence of oppositely charged bodies in this latter zone.

- Moreover, the best results are obtained if the suspended particles are charged and depositedupon the collectin electrode in the aforesaid active portion 0 the electric field, and the collecting electrode is then moved 1nto the inactive portion of the field where means are provided to remove the deposits from the surface upon which they have been gathered. The particles are thus scraped from the collecting electrode in a zone which is virtually unaffected by electrical activity between oppositely charged bodies, and their removal is, therefore, greatl facilitated. By following this method 0 precipitatlon, many of the difficulties frequently encountered in the art are overcome, and the deposited particles are always cleaned from the collecting electrode before it again enters the active portion of the field and has more particles deposited thereupon.

One object of my invention is to provide apparatus for practising the aforesaid electrical precipitating process in which the collecting electrodes, upon the surfaces of which the particles precipitated from the bodies of vapors or gases undergoing treatment are deposited, are continuously rotated between the active and inactive portions of theelectric field established by the opposing electrode system. Means are also provided in the inactive zone and co6perat-. ing with the collecting electrodes for removing the deposited material therefrom in order that a clean'depositing surface may be continuously presented in juxtaposition to the discharge electrode. At the same time, the vapors or gases undergoing treatment are brought into intimate contact with the discharge and collecting electrodes which 7 are embodied in the treating apparatus For a better understanding of the nature and scope'of my invention, reference may be had to the following description and the accompanying drawing in which Figure 1 isa diagrammatic view, partially in elevation and partially in section, of my apparatus installed for treating a body of as in the manner hereinbefore described; *ig. 2 is an enlarged sectional view of a treating apparatus similar to that shown in Fig. 1; Fig. 3 is a diagrammatic and sectional view showing a modified arrangement of the electrodes of Figs. 1 and 2, and Fig. 4 is a view ney 3 serves to conduct the gas undergoing treatment through a passageway intermediate a baffle plate 4 and a rotatable cylindrical electrode 5. The conduit 2 opens into this said passageway thereby insuring that substantially all of the gas issuing from the conduit shall fiow between the baffle plate 4 and the electrode 5.

The electrode 5 has a relatively large and smooth exposed surface to provide a depositing surface for the particles precipitated from the body of gas undergoing treatment. A second electrode 6 having a relatively small exposed surface or serrated edge is positioned in proximity to the upper end of the baffle plate 4 and is spaced from the electrode 5 a sufiicient distance to preclude a break-down of the intervening air space between the two electrodes. The electrode 6 isformed of a conducting iwire of such diameter that it is conducive to the formation of corona emanations when impressed with the operating electrical potential. The electrode 6 is preferably provided with a toothed or serrated edge which is adjacent to the collecting surface as shown in Fig. 4. It is usually preferable to impress electrical potentials of different polarities upon the electrodes, the discharge electrode 6 being impressed with a negative potential and the collecting electrode 5 being impressed with a positive or ground potential. The electrodes are connected to conductors 7 of a high-voltage power circuit.

When the particles held in suspension in the gas undergoing treatment are non-conductive, the exposed surface of the collecting electrode 5 may be made of a conducting material, such as a suitable metal. A brush 8, connected to one of the conductors 7 of the supply circuit, engages the inner surface of the tubular electrode 5. The negative electrode 6 is impressed with a negative potential of such a value that negative corona emanates therefrom. The suspended particles, as the gas flows between the electrode 6 and the electrode 5, become charged negatively by the corona emitted from the discharge electrode 6. In consequence thereof, the negatively charged particles in the vicinity of the point of direct opposition of the discharge or negative electrode 6 and the positive or collecting electrode 5 is very active on account of the proximity of the oppositely charged bodies, while that portion in which the scraping brush 9 is located, due to the non-opposition of the electrodes, is a zone of virtual electrical inactivity.

The brush 9 is shown as connected to the positive conductor of the supply circuit in order to insure that the portion of the surface 5 in juxtaposition to the'electrode 6 shall be maintained with a positive charge. The treated gas, after having been subjected to the corona emanations issuing from the electrode 6, is drawn upwardly through the chimney 3 through which it is expelled.

In Fig. 2, a rotatable collecting electrode 10 is shown as comprising a conducting inner cylinder 11 and an outer electrical insulating or non-conducting cylinder 12. The precipitated particles, initially held in suspension in the gas or vapor undergoing treatment, are held firmly upon the outer surface of the non-conducting cylinder 12, since they are not permitted to lose their electrical charge imparted to them by the corona emanations issuing from the discharge electrode 6. A scraper 13, secured to a wall of the treating chamber, scrapes the collected material from the collecting surface as it revolves. .A brush 14, also conmove the negative charge from the nonconducting surface and to supply a positive charge thereto. A second positive-potential brush 16 engages the inner conducting cylinder 11. The positive charge supplied to the non-conducting cylinder 12, by the brush 14 serves to increase the intensity of the corona discharge from the discharge electrode 6 when the portion of the surface recently supplied with a positive charge comes into the neighborhood of the discharge electrode.

Here again it is apparent that the particles are charged and precipitated in a zone of extreme electrical activity, while the scraping member 13 is positioned in an inactive portion and, therefore, removes the deposited particles in a zone which is unaffected by electrical discharges.

In this instance, each of the electrodes 6 and 10 is continuously charged with an electrical potential of constant polarity by means of a mechanical rectifier 17 of a well known form of construction. The rectifier 17 serves to rectify the alternating currents induced in a high-tension winding 18 of a transformer 19, the primary windmg 20 of which is connected to an alternatin -current supply circuit 21. Any other suita le rectifier may be substituted for the rectifier 17 In Fig. 3, a discharge electrode 6 is positioned intermediate two collecting electrodes 10 each of which is similar to the electrode 10 of Fig. 2. The gas or vapor undergoing treatment is conducted between the rotating cylindrical electrodes 10 and brought under the influence of thecorona emanations from the discharge electrode 6. The precipitated particles collect uponthe exterior surface of the collecting electrodes l0 from which the particles are subsequently removed in any proper manner.

While I have shown and described several embodiments of my invention, it will be understood that many modifications may be made therein without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. In a system for electricall precipitating suspended particles from owing fluid streams and thereafter collecting said particles on. a stream boundary, the combination with a casing forming a treating chamber, of a discharge electrode, a cooperating rotatable collecting electrode, means for rotating said collectin electrode and means for impressing electrical potentials of opposite polarity upon said electrodes, said electrodes being so positioned in said treating chamber that permanently active and inactive zones of the electric fieldextending therebetween are formed.

2. In a system for electrically precipitating suspended particles from flowing fluid streams and thereafter collecting said particles on a stream boundary, the combination with a casing forming a treating chamber,

of a discharge electrode, a cooperating rotatable collecting electrode, means for rotating said collecting electrode, and means for impressing electrical potentials of opposite polarity upon said electrode, said electrodes being so positioned in said treating chamber that permanently active and inactive zones of theelectric field extending therebetween are formed and said collecting electrode being so rotated that the precipitated particles collected thereon are moved from the active to the inactive portion of said field.

3. In a system for electrically precipitating suspended particles from flowing fluid.

streams and thereafter collecting said; particles on a stream boundary, the combination with a casing formin a treating 'Cl1a.mb6I, of a discharge electro e, a cooperating rotatable collecting electrode, means for rotating said collecting electrode, means for impressing electrical potentials of opposite polarity upon said electrodes, said electrodes being so positioned in said treating chamber that permanently active and inactive zones of the electric field extending therebetween are formed and said collecting electrode being so rotated that the precipitated particles collected thereon are moved from the active to the inactive portion of said field, and means for removing said deposited particles from the collecting electrode while in the said inactive zone.

4. In an electrical precipitating system for the treating of gas and vapor, the combination with a casing forming a treating chamber, a discharge electrode, and a cooperating rotatable cylindrical electrode, said electrodes being spaced from one another to permit the body of vapor undergoing treatment to pass therebetween and said electrodes being so positioned in said treating chamber that permanently active and inactive zones of the electric field extending therebetween are formed.

5. Inan electrical precipitating system for the treatment of gas and vapor, the combination with a casing forming a treating chamber, a discharge electrode conductive to the formationof corona emanations, and a cooperating rotatable cylindrical collecting electrode positioned therein, said rotatable electrode comprising a metallic tubular mem- Y active zones of the electric field extending therebetween are formed.

6. In the art of electrical precipitation from flowing fluid streams and in which deposits are collected on a stream boundary,

the method of removing such deposits which consists in establishing a permanently inactive zone in the electric field, shifting the deposit-laden boundary to such zone, and removing the deposits from the boundary while the latter is within the zone.

7. In the art of electrical precipitation from flowing fluid streams and in which deposits are collected on a stream boundary, the method of removing such deposits which consists in establishing a permanently inactive zone in the electric field, moving the deposit-laden boundary laterally of the direction of stream flow into such zone, and

removing the deposits .from the boundary while the latter is within the zone.

8. The method of collecting and removing particles or molecules from a flowing fluid stream, which consists in establishin an electric field with permanently located active and inactive portions to collect the deposit material on a stream boundary within an active portion of the field, shifting the deposit-laden boundary between the active and inactive field portions, and removing the deposits from the boundary while in the inactive portion.

9. In the art of electrical precipitation from fluid streams, opposing electrode systems adapted to produce an electric field having permanently-located active and inactive portions, means for moving the systems relatively to each other to brlng a deposit-collecting face into an inactive portion of the field, and means for removing deposits while in such inactive portion.

10. In the art of electrical precipitation from fluid streams, opposing electrode systems adapted to produce an electric field having permanently-located active and inactive portions, means for moving the collecting electrode system between the active and inactive portions, and means for remov- Dec, 1916.

LEWIS W. CHUBB.