US2501513A

US2501513A - Electrical precipitator

Info

Publication number: US2501513A
Application number: US70239A
Authority: US
Inventors: Carl W J Hedberg
Original assignee: Research Corp
Current assignee: Research Corp
Priority date: 1949-01-11
Filing date: 1949-01-11
Publication date: 1950-03-21
Anticipated expiration: 1967-03-21

Description

March 21, 1950 c. w. J. HEDBERG 2,591,513

' ELECTRICAL PRECIPITATOR Filed Jan. 11, 1949 2 Sheets-Sheet 1 mzwx/ezzm [Mi 41%, I W

March 21, 1950 c.'w. J. HEDBERG ELECTRICAL PRECIPITATOR 2 Sheets-Sheet 2 Filed Jan. 11, 1949 4 i In 1 sh i ilv .lv Iv II II x [1| 1 I III I II Patented Mar. 21, 1950 ELECTRICAL PRECIPITATOR Carl W. J Hedberg, Bound Brook, N. J assignor to Research Corporation, New York, N. Y., a corporation of NewYbrk Application January 11, 1949, Serial No. 70,239

This invention relates to electrical precipitators and more particularly to a dual updraft electrical precipitatorhoused in a single shell or casing.

An object of the invention is to provide an electrical precipitator of large capacity and correspondingly large size for efficiently removing suspended material from a stream of gas especially gas under pressure. The precipitator effectively removes suspended solid catalyst from hot gas streams wherein the solid catalyst is present in relatively high concentrations.

Another object is to provide a precipitator of this type capable of long periods of continuous operation at elevated temperatures and pressures.

Another object is to provide a precipitator having large storage capacity for precipitated material.

Another object is to incorporate two precipitators in a single shell with maximum utilization of available space and height.

These and other objects of the invention are realized in an electrical precipitator having a vertically disposed substantially cylindrical shell, end closure means for the shell, a substantially vertical partition dividing the shell into two substantially semi-cylindrical compartments, partition means extending from the vertical partition to the walls of the shell and defining therewith a central chamber and two lateral gas passages in each of the compartments, the lateral gas passages in one of the compartments communicating with the lower end of the central chamber in the one compartment and the lateral gas passages in the other compartment communicating with the upper end of the central chamber in the one compartment and with the lower end of the central chamber in the other compartment, gas inlet means at the upper ends of the lateral gas passages in the one compartment, gas outlet means at the upper end of the central chamber in the other compartment, and complementary precipitating and collecting electrodes in the central chambers of the compartments.

' 8 Claims. (Cl. 183-7) The invention will be described in greater detail with reference to the accompanying drawings, in which:

Fig. 1 is an elevational view of one form of electrical precipitator in accordance with the invention, the left half thereof being shown in vertical medial section;

Fig. 2 is a vertical medial sectional view of one half of the precipitator of Fig. 1 taken at right angles thereto;

Fig. 3 is a plan view thereof, the top of the casing being removed;

Fig. 4 is a perspective view of a portion of the interior system of partitions that direct the flow of gas through the precipitator; and

Fig. 5 is an enlarged vertical sectional view through one of the collecting electrodes of the precipitator.

Referring to the drawings, particularly to Figs. 1 and 2 thereof, the precipitator shown has a shell or casing including a central cylindrical section [0, a bottom conical section II and a top conical or dome-shaped section l2. The top and bottom sections of the shell form end closures for the central cylindrical section thereof. The shell may be fabricated of steel plate welded to form a gastight enclosure capable of withstanding internal superatmospheric pressures of the prder of one or two atmospheres at gas temperatures of the order of 300 F. to 650 F.

Pressures and temperatures of these magnitudes are encountered in the recovery of catalyst from fluid catalyst regenerators, to which use the precipitator of the invention is advantageously adapted. The shell of a typical precipitator may be of the order of eighty feet in height.

A substantially vertical partition l3 divides the interior of the shell into two compartments A and B of substantially equal size and shape. As seen in Fig. l, the upper part I4 of the central partition is inclined slightly to the left of the center plane to join the top cone l2 at one side of the gas outlet 15.

Extending from the central partition I3 approximately at right angles thereto and across compartment A near the sides thereof are vertical partitions IS. The partitions I6 rise from the level of the I-beams I! to the line I 8. Inclined segmental baflles I!) extend from the top edge of partitions Hi to the side walls of the shell to provide two downwardly opening lateral gas passages A, A in compartment A. Gas inlet pipes 20 project through the walls of the shell into the gas passages A, A, are bent downwardly therein, and terminate in downwardly opening, flared gasinlet distributors or wear boxes 2 i. i

A bafile 22 disposed parallel to the center partition I 3 defines, with the partitions and shell walls hereinbefore described, a central precipitating chamber A". The inclined segmental bafile 23 that extends from the top edge of the bafile 22 to the wall of the shell prevents circulation of gas in the zone between the bafile 22 and the shell wall.

I-beams I! support a perforated gas distribut ing plate 24 that underlies the precipitating 3 chamber A". A grill 25, positioned below the gas distributing plate 24 delimits a dust receivirlilg 1hopper 26 in the bottom of the precipitator s el In compartment B, vertical partitions 21, that are substantially aligned with the partitions l8 of compartment A, extend at right angles from the central partition l3 to the shell walls. 1Partitions 21 extend from the level of the gas distributing plate 24 to the roof of the shell, the upper portions 28 of the partitions being slightly inclined towards each other and being joined to the upper part l4 of the central partition along the abutting edges 29. The lateral gas passages B thereby formed in compartment B communicate at the top through openings 30 with the top zone of compartment A. Gas passages B are open at their bottoms.

A transverse baflle 3!, similar to the baiiie 22 of compartment A, is disposed in compartment '13 in parallel relation to the center partition 13 to complete the formation of the central Dre.- cipitating chamber 13''. A segmental baffie 32 closes the zone between the shell walls and baiile 31 to prevent flow of gas therethrough.

Gas flow through the precipitator is readily visualized from Fig. 4. As shown therein, gas enters the precipitator through the inlet conduits Z8 and flows from the distributor 21 down through the lateral gas passages A, A. Emerging from the bottom outlets of the lateral gas passages A, A, the streams of gas flow towards each other centrally of the compartment A and then pass upwardly through the perforated distributing plate 24 into the central precipitating zone A".

The gases pass upwardly through the precipitating zone A", in which they are subjected to elec-. trical precipitation conditions as will be more fully explained hereinafter, and issue into the upper part of compartment A. From the upper part of compartment A, the gas stream is split into two streams which flow through the openings 3t and down through the lateral gas passages B in compartment B. From the bottoms of gas passages 13', the streams of gas flow under the distributing plate 24 and up through the perforations thereof into and upwardly through the precipitating chamber B" in which the gases are subjected to a second cleaning operation.

Cleaned gases leave the precipitator through the outlet it.

The extended surface collecting electrodes that are disposed in the precipitating chambers A" and B are advantageously of the type referred t s t ip l t o esto Figs, 1, 2 and 5, a plurality of such collecting electrodes, desi nated generally by the reference numeral 33, are vertically disposed within the precipitating chambers in parallel spaced relation so that the gas to be cleaned travels upwardly therebetween,

As shown in Fig. 5, the electrodes 33 include vertical frame members 34, a plurality of which are spaced horizontally in the structure and to which are welded or otherwise suitably afiixed the outwardly-projecting brackets or hangers 35. Plate members 36 are secured to the electrode structure by the hangers. The upper edges of h t s 35 are t rned inward y to fo m h o s 3' hat are en aged on he n o he hangers. Eate 3 exten general y paral e to t e p ane o the el ctro e n. he area 31' and. re b nt ou wardly at 38 to form flared portions merging into h limited. e ilous .1;- The, bo tom. edges of the plates ar termed. shown at 8 and are Referring particularly gripped under the finger portions 39 of the next lower set of hangers. It will be seen that the lower edge of each plate 36 is overlapped by the outwardly flared upper portion of the immediately subjacent plate to provide an upwardly facing slot 40 running transversely of the electrode structure and communicating with the hollow interior of the composite electrode.

As seen in Figs. 1 and 2, the bottom portions of the plate electrodes 33 are provided with triangular hollow sections 4| that lead into dust chutes 42 extending into the dust receiving hopper 26.

Dust that is precipitated on the collecting electrodes 33 is removed therefrom by rapping the electrodes with a conventional rapping device (not shown). Precipitated dust falls from the collecting plates 36 through the transverse slots 40 and into the hollow interior of the collecting electrodes. Within the electrodes the collected dust falls into the triangular bottom sections 4! thereof and down through the chutes 52 into the hopper 2B.

Complementary precipitatin or discharge electrode assemblies 43 are interspaced between the extended surface electrodes 33. The discharge electrode assemblies include horizontal discharge elements 44, that may be twisted square rods, fine wires, or the like, which elements are mounted in frames having parallel vertical hangers 45 suspended from the cross members 46. The frames have central and

bottom braces

47 and 48. The several electrode supporting frames are carried by stringers 49 that are supported by beams which, in turn, are suspended by rods 5! and 52 from insulated mounting devices located in the insulator housings 53 and 54. A rapping mechanism is inclosed in the extension 55 of the housing 54 for rapping dust from the discharge electrodes. Longitudinal tie rods 56 join together the lower ends of the discharge electrode frames and provide substantial bracing for the discharge electrode assembly.

A similar arrangement is employed for mounting the discharge electrodes in the precipitating chamber B".

It will be understood that the complementary electrodes used in the precipitating chambers of the apparatus of the invention may be of any suitable construction. Further details of those shown and described herein by way of illustration are given in my copending application Serial No. 44,878, filed August 18, 1943, for Electrical precipitator with dual discharge electrodes.

In operation, the complementary electrodes in precipitating chambers A" and B" are conventionally energized from a source of high voltage current (not shown). One terminal of the high voltage source may be grounded. Since the shell of the precipitator is also grounded, one side of the, circuit is completed to the collecting electrodes through the shell and, the, collecting electrode supporting structure. The other terminal of the, current source may be connected to the discharge electrod assemblies, by insulated cables (not shown) connected to the discharge electrode assembly supporting structure in the insulator housings 53, Bietc. It, will be understood that various systems for energizing the electrodes may be employed and that the electrodes in the separate precipitating chambers may be energize from separate current sources as well as from a single current source.

Gas, to b cle ned. such. as. hot. gas un r upe atmospheric pressure from-a fluid catalyst regenerator bearing in suspension relatively high concentrations of solid catalyst of small particle size, is fed to the precipitator through the inlet conduits 20. As described hereinbefore, the gas passes down through the lateral gas passages A, A and up through the first central precipitating chamber A" in which it is subjected to a primary stage of cleaning. The partiallycleaned gas then flows down through the lateral gas passages B, B and up through the second central precipitating chamber B" in which it is subjected to a secondary cleaning step. The cleaned gas issues from the precipitator through outlet l5.

Catalyst that is precipitated on the collecting electrodes 33 is periodically removed. therefrom by rapping the electrodes. The catalyst removed from the electrodes passes into the lower conical shell section ll through the interior of the collecting electrodes and through the, dust chutes 42. Catalyst is removed from the lateral halves of the conical section II through the outlets 5B and 5! as often as may be desirable. Occasionally, the discharge electrode assemblies may be rapped to dislodge any catalyst that may accumulate thereon.

From the foregoing description, it will be seen that the present invention provides an electrical precipitator for efficiently cleaning at high capacity large volumes of hot gases under pressure that carry a heavy burden of suspended material. The invention provides for utilization of a portion of the shell volume, which cannot be economically used for placement of electrodes, for internal gas ducts for distribution of the gases to the electrodes.

Various modifications of the precipitator herein shown and described can be made without departing from the invention. For example, the precipitating chambers A" and B" may each be divided into two parallel: chambers by a central vert cal bafiie disposed parallel to the side partitions 21.

I claim:

1. An electrical precipitator comprising a vertically disposed supstantially cylindrical shell, end closure means for said shell, a substantially vertical partition dividing said shell into two substantially semi-cylindrical compartments, partition means extending from said vertical partition to the walls of the shell and defining therewith a central chamber and two lateral gas passages in each of said compartments, the lateral gas passages in the first of said compartments communicating with the lower end of the central chamber in said first compartment and the lateral gas passages in the second of said compartments communicating with the upper end of the central chamber in said first compartment and with the lower end of the central chamber in said second compartment, gas inlet means at the upper ends of the lateral gas passages in said first compartment, gas outlet means at the upper end of the central chamber in said second compartment, and complementary precipitating and collecting electrodes in the central chambers of said compartments.

2. An electrical precipitator as defined in claim 1 wherein gas inlet openings are positioned on opposite sides of the shell and a gas =outlet opening is positioned substantially centrally in the top end closure of the shell.

3. An electrical precipitator as defined in claim 1 wherein the lower portion of the shell provides an inverted conical hopper to receive precipitated material.

4. An electrical precipitator as defined in claim 1 wherein the precipitating electrode systems in the two central chambers are supported therein by suspension members passing through the top end closure of the shell.

5. An electrical precipitator as defined in claim 1 wherein the collecting electrodes comprise extended surface members disposed in two substantially parallel arrays spaced apart to define an interior passage and openings between adjacent members for the access of precipitated material into said passage.

6. An electrical precipitator as defined in claim 5 including conduits extending downwardly from the lower ends of the interior passages in the collecting electrodes a substantial distance into the lower portion of the shell.

7. An electrical precipitator comprising a vertically disposed shell, top and bottom closure means for said shell, a substantially vertical part1 tion dividing said shell into two compartments, a second partition in one of said compartments extending from said vertical partition to the wall of said shell and defining therewith a vertically extending gas passage, said gas passage communicating at its upper end with the upper portion of the first of said compartments and at its lower end with the lower portion of the second of said compartments, gas inlet means in the lower portion of said first compartment, gas outlet means in the upper portion of said second compartment, whereby gas admitted through said inlet means flows up through said first compartment, down through said gas passage, up through said second compartment and is exhausted through said outlet means, and complementary precipitating and collecting electrodes positioned in the upfiowing gas in said compartments.

8. An electrical precipitator comprising a vertically disposed substantially cylindrical shell, top and bottom closure means for said shell, a substantially vertical partition dividing said shell into two substantially semi-cylindrical compartments, a second partition in the second of said compartments extending from said vertical partition to the wall of said shell and defining therewith a vertically extending gas passage, said gas passage communicating at its upper end with the upper portion of the first of said compartments and at its lower end with the lower portion of the second of said compartments, gas inlet means in the lower portion of said first compartment, gas outlet means in the upper portion of said second compartment, whereby gas admitted through said inlet means fiows up through said first compartment, down through said gas passage, up through said second compartment and is exhausted through said outlet means, and complementary precipitating and collecting electrodes positioned in the upfiowing gas in said compartments.

CARL W. J. HEDBERG.

REFERENCES CITED The following references are of record in the fileof this patent:

UNITED STATES PATENTS Number Name Date 1,800,529 Home Apr. 14, 1931 1,981,455 Knight Nov. 20, 1934 FOREIGN PATENTS Number Country Date 219,570 Great Britain July 31, 1924