US2800192A - Electrostatic precipitator - Google Patents

Description

E 1957 M. ROBERTS 2,800,192

' ELECTROSTATIC PRECIPITATOR' Filed Oct. 10, 1955 INVENTOR LAWRENCE M. ROBERTS ATTORNEY United States PatentQ ELECTROSTATIC PRECIPITATOR Lawrence M. Roberts, Bound Brook, N. J., assignor to Research Corporation, New York, N. Y., a corporation of New York Application October 10, 1955, Serial No. 539,510

3 Claims. (Cl. 183-7) This invention relates to new and improved apparatus for electrostatically removing suspended particulate material from gas streams and more particularly to electrostatic precipitators comprising at least 'two vertically superposed precipitation sections.

It is a principal object of the present invention to provide electrical precipitation apparatus comprising at least two vertically superposed precipitation sections permitting substantial savings in the construction of the shell, hopper, flue, piping and valves and in the space requirements of the assembled unit.

t A further object is to provide such a device having liquid flushed collecting electrodes wherein the flushing liquid supplied to the uppermost section of the electrostatic precipitator is collected and distributed to the electrical precipitation section therebelow.

A further object of the invention is to provide such a device wherein the gas stream treated in the lowermost section is collected and redistributed to the uppermost sections providing uniform gas distribution and uniform particle redistribution in the gas stream to be treated in the subsequent gas treating sections.

These and other objects and advantages are provided by the apparatus of the present invention which generally comprises a housing, a wall dividing the housing into an upper and lower gas treating chamber, the dividing wall being secured to the inner vertical surface of the housing and sloping generally upwardly therefrom, a first horizontal header sheet in the lower gas treating chamber, a second horizontal header sheet in the upper gas treating chamber, a plurality of collecting electrode openings in the first and second header sheets, a tubular electrode secured in each of the openings in the first and second header sheets, the header sheets forming with their respective tubular electrodes flushing ponds, a discharge electrode extending through each of the collecting electrodes, dirty gas inlet means below the first header sheet, clean gas outlet means above the second header sheet, means conducting gas from the lower gas treating chamber to the upper gas treating chamber said means including a conduit extending upwardly from the dividing wall to a position between the tubular collecting electrodes below the second header sheet and drain means connecting the upper surface of the dividing wall and the upper surface of the first header sheet.

The invention will be more particularly described with reference to the illustrated embodiments of the invention wherein:

Fig. 1 is a vertical view in partial section of an electrostatic precipitator constructed in accordance with the principles of the present invention and Fig. 2 is a section substantially on line 22 of Fig. 1.

- from the gas stream to be cleaned from the shell of the Referring to the drawings, 10 generally designates the I Below the dividing wall 22 is provided a header or tube,

sheet 24 provided with a plurality of openings therethrough into which are fitted a plurality of tubular extended surface collecting electrodes 26. The upper ,ends of the tubular collecting electrodes 26 project above the header sheet 24 and cooperate with the header sheet to provide ponds for electrode flushing liquids as is well known in the art.

Centrally disposed within each of the collecting electrodes 26 is a discharge electrode 28 suspended from bus bars 30 supported by insulators in insulator housing 31, and connected to a source of high voltage. The lower ends of the discharge electrodes 28 are secured to a s'teadying frame 32.

Gas treating section B, positioned vertically above gas treating section A, includes a header or tube sheet 34 provided with a plurality of openings therethrough into each which is secured a tubular extended surface collecting electrode '36. The upper ends of each collecting electrode 36 projects above the upper surface of the tube sheet 34 to provide for liquid ponds as defined by the collecting electrodes, the tube sheet 34 and radial partition members 38. The radial partition members 38 divide the collecting electrodes into groups whereby even flow of flushing liquid may be provided for the electrodes without the necessity of leveling each electrode in the entire section relative to each other.

Centrally positioned within each of the collecting electrodes 36 is a discharge electrode 40 supported at its upper end by bus bars 42 suspended from rods 44 connected to insulators in insulator housings 48. The lower ends of the discharge electrodes 40 are attached to steadying frames generally indicated at 50. Above the bus bars 42 are provided a plurality of conduits 52 having depending spray heads 54'secured thereto to provide a liquid spray for maintaining pools of liquid in the liquid ponds and for cleaning the discharge electrodes and associated high tension frames of deposited material. Conduits 56 are also provided in the upper section of the precipitator above the upper surface of tube sheet 34 for directing flushing liquid into the plurality of ponds; there being at least one conduit 56 for each of the plurality of ponds.

The tube sheet '24 of precipitator section A and the dividing wall 22 are divided into segments by members 60 and 62 respectively positioned vertically below the members 38 forming the plurality of ponds in the upper precipitator section B. Each 'ofthe areas formed by par? tition members 62 and thedividing wall 22 are connected to the ponds formed by members 60 and header sheet 24 by conduits 64, which are shown in the disclosed form of the invention as terminating slightly above the upper surface of tube sheet 24 but below the level of the liquid in the flushing ponds of section A whereby gas passing through the tubular collecting electrodes 26 will be prevented from flowing upwardly through the drain pipes 64.

In order to direct the gas stream being cleaned, after passing through the lowermost section A, to the second section B of the precipitator a conduit generally designated 66 extends from the lower surface of the dividing wall 22 upwardly between the collecting pipes 36 of precipitator section B to discharge the gas above the lower ends of the collecting electrodes and below tube sheet 34.

In operation of the apparatus of the invention gases to be cleaned containing suspended particulate material enter the precipitation chamber A through dirty gas inlets 68 opening through the wall of the housing slightly below the header sheet 24. The gases fiow downwardly to the open ends of collecting electrode tubes 26 and pass upwardly therethrough where a portion of the particulate material suspended in the gas stream is electrostati cally precipitated upon the inner surfaces of the tubes. The gases issuing from the upper ends of the collecting electrode tubes 26 collects above the tubes and flows upwardly through conduit 66 and out into the space about the collecting electrodes 36 of precipitator section B where the gas again flows downwardly to the open ends of tubes 36 and upwardly therethrough. It will be noted that the gas issuing from the collecting electrode tubes of section A is remixed 'and'distributed to the collecting tube electrodes of section B in the space between the upper surface of header sheet 24 and lower surface of the dividing wall 22 and in the restricted conduit 66. The gases after passing through the second'section of the electrostatic precipitator issue as clean gases from the precipitator outlet 16.

Particulate material from the gas stream deposited upon the discharge electrodes and their supporting frame are washed therefrom by liquid issuing from spray 54 while the particulate material precipitated on the inner surfaces of the tubular collecting electrode 36 are flushed therefrom by liquid directed to the ponds by pipes or conduits 56. The liquid from the ponds and the sprays 54 containing the removed particulate material flows from the lower ends of the collecting and discharge electrodes of section B to the upper surface of the dividing wall 22 where the liquid flows through drain pipes 64 to provide flushing liquid for the collecting electrodes 26 of section A. Spray means 70 similar to the sprays 54 of section B are provided in section A to maintain the discharge electrodes and their supporting frame free of deposit of particulate material. The flushing liquid containing the particulate material from both sections A and B collect in the lower end 18 of the casing 10 andare drained therefrom through suitable means connected to outlet 20.

From the foregoing discussion it will be seen that the flushing liquid for the tubular collecting electrodes 36 of section B is reused to provide the flushing liquid for the collecting electrodes 26 of section A thereby substantially reducing the cost of flushing liquid and increasing the concentration of the particulate material in the liquid collected at the lower end of the precipitator.

In general flushing liquid required for each pipe in an electrostatic precipitator having a diameter of about 12 inches is about 1 gallon per minute. It is therefore seen that on electrostatic precipitators of the type disclosed in the present inventionhaving, for example, 300 electrodes in each section A and B the saving in flushing liquid alone is about 300 gallons per minute.

'From the foregoing description it will be seen that the precipitator of the present invention fully accomplishes the aims and objects hereinbefore set forth. It will also be apparent that the embodiments shown are only exemplary of a particular form of the apparatus for collecting suspended particles in gas streams and that various modifications can be made in the construction and arrangement of the elements thereof without departing from the scope of the present invention.

I claim:

1. An electrostatic precipitator comprising a housing, a wall dividing the housing into upper and lower gas treating chambers, said wall being secured to the inner vertical surface of the housing and sloping generally upwardly therefrom, a first horizontal header sheet in the lower gas treating chamber, a second horizontal header sheet in the upper gas treating chamber, a plurality of collecting electrode openings in the first and second header sheets, a tubular electrode secured in each of the openings in the first and second header sheets, the header sheets forming with their respective tubular electrodes flushing ponds, a discharge electrode extending through each of the collecting electrodes, dirty gas inlet means below said first header sheet, clean gas outlet means above the second header sheet, means for conducting gas from the lower gas chamber to the upper chamber, said means comprising a conduit extending upwardly from the dividing wall to a position between the tubular collecting electrodes below the second header sheet, conduit means for providing flushing liquid forthe ponds associated with the upper header sheet and drain means connecting the upper surface of the dividing wall and the upper surface of the first header sheet to provide liquid for the flushing ponds of said lower gas'treating chamber.

2. The apparatus defined in claim 1 wherein division strips extending vertically upwardly from the upper surface ofthe' first and second header sheets and the dividing wall divide said'members into a plurality of segmental units.

3. An electrostatic precipitator comprising a housing having generally horizontal extending partition means secured, to the inner vertical surface of the housing and sloping generally upwardly therefrom to provide a plurality of verticallysuperposed gas-treating chambers, each of said chambers having a transverse header plate with tubular collecting electrodes disposed in openings in said header plate to depend therefrom and to extend above said header plate 'to form a flushing liquid pond thereabove, a discharge electrode extending through each collecting electrode, gas inlet'means below the header plate of the lowermost chamber, gas outlet means above the header plate of the uppermost chamber, conduit means extending upwardly from each of the partition means to a position between the tubular collecting electrodes in the chamber thereabove to conduct gas from each lower chamber to a position between the collecting electrodes and below the header plate of a superposed chamber, conduit means for supplying flush liquid to the pond above the uppermost chamber and drain means for conducting flushing liquid collected at the bottom of an upper chamber to the pond above the header plate of a lower chamber.

References Cited in the file of this patent UNITED STATES PATENTS 185,900 Ellerhorst Jan. 2, 1877 1,613,352 Kobernik Jan. 4, 1927 2,027,615 Prutzman Jan. 14, 1936 2,443,780 7 Wintermute June 22, 1948 2,701,028' 'Eilenberger Feb. 1, 1955

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