US2233639A

US2233639A - Electrical precipitator

Info

Publication number: US2233639A
Application number: US313243A
Authority: US
Inventors: Edward H R Pegg
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1940-01-10
Filing date: 1940-01-10
Publication date: 1941-03-04
Anticipated expiration: 1958-03-04

Description

Fil ed Jab. 10, 1940 5 sheets -she et 1 WITNESSEISI: i

INVENTOR Edward [ZR I BY ATTORNEY -Mar ch 4, 1941. E. H. R. PEGG 2,233,639

ELECTRICAL PREcIP'i'rA'roR Filed Jan. 10, 1940 3 Sheets-Sheet 3 WITNESSES:

INVENTOP I EdwardHRPea @MM/x za MW W ATTORNEY Patented Mar. 4, 1941 UNITED STATES ELECTRICAL PRECIPITATOR Edward H. R. Pegg, Lakewood, Ohio, assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa, a corporation of Pennsylvania 6 Claims.

My invention generally relates to electrical precipitators for removing dust from a gaseous stream by electrically charging and precipitatin the dust, but more particularly, relates to the creation of a precipitator in the form of a unit which can be readily and easily installed and incorporated into new, or existing, moderatelyslzed, ventilating systems, or air-conditioning systems, or the like, such as, for example, central air-heating systems for private homes or residences, for cleaning air to be breathed.

A precipitator of the type to which my invention relates usually comprises an ionizing zone for ionizing or charging the dust particles in the gas-flow, and a precipitating zone for precipitating the ionized or charged dust upon dust-precipitating or dust-collecting means, and itis an objector my invention to provide such a precipitator, in the form of a unit which will have a low initial cost, which will be rugged in use, which will have a low up-keep expense, and which will require but little, if any attention over long periods of time, except for occasional washing of the dirt accumulated on the collecting means of the precipitator.

It is a further object of my invention to provide an electrical dust-precipitator unit which comprises an outer sheet metal cabinet or casin for encasing the primary working parts of the .unit, which are usually operated at high potentials, but the casing, nevertheless, having provisions in the form of closure means for permitting ready access to these parts, and provided with safety features which will remove any high potentials on the parts before permitting such access.

In the preferred form of my invention, the casing is provided with an opening in its top and an opening near the bottom in one of its sides, the openings being defined by flanges for connection to ducts or conduits of the particular system of which my unit is to be part. For precipitating the dust a plurality of precipitator cells are disposed in the casing intermediate the openings, spaced from the top and bottom of the casing. Thecells are preferably of the type described and claimed in my copending application, Serial No. 286,577, filed July 26, 1939, and assigned to the Westinghouse Electric 8: Manufacturing Company. The construction of the casing and the cells is such-that the gas-flow through the casing from one of the aforesaid openings to the other may be in either direction, it being only necessary to turn or invert the ,cells on their supports for a reversed gas-flow. Consequently, my

Application January 10, 1340, Serial No. 313,243

unit can be adapted to an air treating system regardless of the direction of flow in the system.

An important feature of my precipitator unit lies in the simple provisions by means of which its precipitating means can be washed without the need of removing them from the casing or disturbing them in any way. To this end the hereinbefore-mentioned closure means includes a door for an opening in a side of the casing, which is above the dust-precipitating means and through which a water hose may be inserted for playing a stream of water completely over the dust-precipitating means. The part of the casing below this last opening is made water-tight, and this applies also to any further closure means below the cell opening so that the washing water will flow to the casing bottom which is sloped downwardly to a drain. The drain is preferably relatively small compared to the cross-section of the air-flow conduits and openings, and when connected to a waste pipe afiords suflicient airflow resistance to prevent the flow of any appreciable amount of air through the drain during the operation of the unit. However, a separate valve, or other suitable air-flow-restricting means, may be employed, if desired, to close or restrict the drain when the unit is being used for cleaning air.

My invention also utilizes a power-pack of any known type to convert the conventional house voltage supplies to the necessary higher values of unidirectional voltages required by the electrical precipitator unit. In my preferred construction, a power-pack is mounted in the top of the casing above the dust-precipitating means -in such a manner as to interfere only slightly, if at all, with the gas flow; and it is fully encased so that ,water cannot spray or contact any of the electrical elements of the power-pack during washing of the dust-precipitating parts of the precipitator unit. a

Further features, advantages, arrangements, and objects of my invention will be apparent from the following description thereof, which should be taken in conjunction with the drawings, drawn on varying scales, in which:

Figure l is a perspective view of my precipitator unit;

Fig. 2 is a front elevational view thereof with the closure means shown in open position to expose the working parts inside the unit;

Figs. 3, 4 and 5 are, respectively, side elevational, top plan, and front elevational, somewhat schematic and enlarged, views of a precipitator cell built in accordance with the disclosure in my aforesaid application. Figs. 3 and 5 show the cell inverted with respect to the cells shown in Fig. 2, with Fig. 3 diagrammatically indicating the position of theinverted cellin the unit.

Figs, 6 and 7 'are, respectively, top plan, andfront views, somewhat enlarged, of an open framework secured inside the casing for sup-' porting from one to three precipitator cells, such as shown in Figs. 3-5.

Fig. 8 is an enlarged view of a safety provision V for delaying the opening of the top door of the unit; Y

' side l2, and a front side l4. The unit is preferably adapted for a vertical gas-flow and, consequently, the side walls are elongated vertically. A plurality of supporting legs iii are provided at each of the bottom corners of the casing which permits the bottom floor to be sloped for draining,

The top side 4 of the casing has an opening I defined by upright flanges l 8, and a second opening is provided at the bottom of one of the lateral sides II), the opening being defined by protruding flanges 20. The openings are sufficiently large to accommodate the required gas-flow through the unit.

The front side l4 of the unit comprises closure means in the form of a lower door 22, and an upper door 24. The doors cover substantially the full area of the front side of the casing whichis provided with ledges 2G, in line with the outer edges of the doors, to provide part of door frames for the doors 22and24. The remaining parts of the door frames are obtained by means of a cross bar or channel 28 secured in the casing laterally across the front side of the unit at the dividing line between the upper and lower doors.

The ledges 26 and crossbar-28 definea lower' opening and an upper opening 32 in the front side of the casing.

The doors are hinged to a vertical edge of side H by means of hinges 34, and window locks 36, or other suitable latches are provided on the opposite edge of the front side by means of which the doors can be tightly closed. In order tov further assure a gas-tight and water-tight closure means, compressible strips 38', such as felt, sponge rubber or asbestos, or other suitable gasketing material, are secured to the four edges of each 'of the

doors

22 and 24, these strips being compressed against the ledges 26 and cross bar 28 when the doors are latched closed. For reasons which will later become apparent, the lower door is provided with an interlocking means in the form of an upwardly-projecting bar 40 in the path of a lower edge 42 of the upper door so that the lower door cannot be opened until after the upper door is opened and, conversely, the upper-door cannot be closed until after the lower door is closed. This bar 40 is adapted to contact and abut the bottom edge 42 of the upper door, which is'formed by securing the bottom compressible strip on the upper door somewhat above its bottom extremity.

Fig. 9 is an enlarged perspective view ofthe Secured inside the casing is an open, metal framework 44 disposed below the cross bar 28 a distance which is slightly larger than the height of the cells 46 of the precipitating-means, which are supported or rest on the-framework. The framework substantially fits the interior cross section ofthe unit and comprises a front angle bar 48, a rear angle bar 50, side angles 52 and v 54, and-spaced intermediate T-memb'ers parallel to the

side members

52 and 54.

The open distance between front and rear bars 48 and 50 is slightly less than the length of the cells 46; and the open distance between the

side angles

52 and 54 is, preferably, slightly less of the cells 46 may rest thereon.

Each of the precipitating cellscomprises, generally, an open-ended, outer, metallic casing 66, whose side and end walls define a rectangular section slightly greater in size, but geometrically similar, to the

spaces

60, 62 and 64. Within this casingis disposed an ionizing means and precipitating means successively in the direction of the gas-flow. The ionizing means comprises a plurality of curved grounded

electrodes

68 and 10 secured in spaced relation in the casing, with ionizing wires 12 disposed substantially centrally between the electrodes. I prefer to employ the construction for an ionizing means such as shown in my aforementioned application, one of the features of which includes detachably mounting the electrode 10 to the casing by means of a hook member 14 secured to the casing and engaging a pin 16 attached to the electrode 10. The other end of the electrode is provided with a threaded plug into which may be screwed a bolt 18 for securing the ground electrode in place by first hooking the pin 16 over the hook member 14 and then threading the bolt-18 into the plug at the end of the ground electrode, thebolt extending through a suitable aperture in an end side of the casing. I

The ionizing wires are supported by this ground electrode through the medium of a plurality of insulators having one end bolted to the electrode and supporting a metallic bar 82 shorter than, and parallel to, the ground electrode. Suitable ionizing-wire supporting arms, such as end supports 84 and intermediate supports 86, depend from this bar 82 and support the ionizing wires. Across the full length of the interior of the cell are a plurality of spaced'parallel plates 81 alternate ones of which are grounded with the remaining plates electrically insulated from the casing and the grounded plates. It

the dust in the gas stream is suitably charged. The gas including the charged dust then passes between the-spaced dust-collecting plates of the precipitating zone where the dust is precipitated 5- while the clean gas flows out through the other open end of the casing. Any suitable air-propelllhg means may be employed for forcing the air through the cells, such air-propelling means being usually part of the system into which the unit is incorporated. In mounting the cells in the casing the ionizing portion is placed forwardly in the gas stream so that the gas will pass through it before it passes through the dust- -collecting means comprising, the alternately insulated and uninsulated spaced plates.

In the construction I employ each cell is placed in the casing with the ionizing portion either toward the top or toward the bottom, depending on the direction of gas-flow through the unit.

In Fig. 2 the ionizing portion is shown at the bottom of the cells and is so indicated by the bars 82 below the framework 44; while in Fig. 3 the cell is shown with the ionizing means toward the top of the unit. In Fig. 2, of course, the gasflow would be in a direction from the lower opening to the upper opening, while in the embodi-- ment of Fig. 3, the gas-flow would be in the reverse direction. Sufliciently large regions are provided above and below the cells for uniform velocity distribution of the gases passing through the cells.

Bafiles such as 88 and 90 may be disposed below the framework to deflect and guide the gas stream that may be flowing to or from the opening in the side wall I0. These baflies preferably terminate in the region below'the cells so as.not to interfere with the drainage of water that may flow downwardly during washing of the cell units.

The cells rest on the surfaces of the frame- 40 work 44 and are placed side by side. The lower edges of the cell casing 66 rest on, and can slide on, the members comprising the framework, with the sides of a casing resting, forexample, on the

members

54 and 58, and the cell ends on the side 45

angles

52 and 54. The cells are preferably inserted without the removable item comprising the. grounded electrode I0 and the parts secured to it. This item is added after the rest of the cell has been placed in proper position in the casing 2. The gas-cleaning means of this embodiment is energized by unidirectional voltage in accordance with the teachings more particularly described in Patent No. 2,129,783, granted September 13,

1938 to G. W. Penney, and assigned to the West- 55 inghouse Electric & Manufacturing Company. To

this end the ionizing means is positively energized by means of a conductor schematically designated by 1+ and the insulated plates are positively energized by a conductor schematically indicated at P+. The cell casing 58 is grounded by virtue of its contact with the metal framework 44 which, in turn, is suitably welded or otherwise secured to the sides 8, I0, and I2 of the casing 2, preferably gas-tightly.

55 To convert the commercially-available household voltage supplies to values required by the electrical precipitating means, I secure a powerpack, indicated in its entirety by the reference character 92, inside the casing. The power-pack 70 is so arranged that it will fit a long narrow enclosure in an upper corner of the casing 2,, and is completely wired for connection to the conventional house wiring circuit. Leads 94 may terminate in the usual plug adapted to engage any suitable outlet.

The power-pack comprises a pair of rectifying tubes 95, a pair of condensers 96 and .90, each paralleled by resistances I00 and I02, respectively,

indicating device may be an ammeter which, by 10 the deflection of its pointer, will give an indication of the operating condition of the precipitating means, and the door switch IIO controls the energy supply to the power-pack.

The respective parts comprising the power- 15 pack are all mounted within the substantially gastight and water-tight inner casing II2 having a door II4 hinged at its bottom and adapted to be maintained closed by any suitable latching means, such as, for example, a pair of bolts projecting 20 through apertures I I6 in the door and engaging threaded lugs H8 secured to the inside of the casing H2.

The indicating instrument is mounted on the front of the power-pack casing, and the upper 25 door 24 is closed, and since the lower door 22 cannot be opened unless the upper door is first in openposition, it is quite obvious that access to the interior of the unit cannot be gained until after the energized circuit is broken.

As a further precaution against excess volt- 40 ages existing on the precipitator parts before the door 24 can be fully opened, I provide a time delay means in .the form of a screw I24 having a head I25 outside of the door 24, and a shank I28 extending inside of it, the shank'being threaded 5 for the major portion of its length but being smooth at the portion which passes through the cooperating aperture in the door 24. A cotter pin I30 extends through the shank to prevent the screw from being withdrawn through the aper- 50 ture of the door. The screw I24 is adapted to be screwed into a nut I32 welded, or otherwise secured, to the front wall of the power-pack casing. The threaded in the doors,.the screw I 24 must be threaded substantially completely into the nut before the cont-actor I22 closes the circuit across the contacts I20. In opening of the doors this screw must be unthreaded and the first movement opens the circuit to the power-pack. Subsequent unthreading provides a time delay featurepermitting the energy of the condensers to be drained by their parallel resistors so that by the time the screw I 24 is completely unthreaded from the nut, substantially no voltage is present on the condensers.

The power-pack casing has. suitable apertures through which suitable conductors. extend for connection to the proper parts of the cells, al-

' cell to another so that the conductors need be connected only to onecell.

' Water.

In the event that the unit is to be employed with less than .the number of cells for which it was designed, one or more plates M2 may be employed to cover the openings in the framework 44 'not provided with cells.

Inasmuch as electrical precipitators operate on the principle of collecting dust upon suitable electrodes, in this case the parallel plates in the cells, it is advisable, for maximum efiiciency, to occasionally wash the accumulated dirt from these plates. In the unit of my invention, it is unnecessary to remove any of the cells for this purpose although they are removably mounted therein. For washing the plates the upper door 24 may be opened while the lower door remains tightly latched so that, consequently, the part of the unit below the upper door is substantially water-tight. through the upper opening 32 and a water stream played upon the precipitating cells 46 until they are thoroughly cleaned. The bottom fioor 6 of the casing 2 is sloped downwardly toward a con tral drain I44 which may be connected .to any suitable waste pipe system for draining offthe This drain may itself provide a suitable grounding connection for the unit, but obviously any .other grounding means may be employed. After a Water washing, it may be desirable .to spray oil on the precipitating parts of the unit.

From the foregoing it is at once perceived that -I have provided a very simply constructed unit which may be readily installed in existing airtreating systems, .the ducts or conduits of which are schematically indicated bythe broken lines of Fig. 2. This unitcontains all the necessary apurtenances, in the form of precipitating cells and power-pack, required for the cleaning of air. Moreover, access to the inside of the unit for cleaning or for servicing can be easily hadwithout any danger to .the operator in view of the safety and protective precautions incorporated in the unit.

The lower door 22 is of such height that when closed it prevents water from getting out of the cabinet' while the cells are being washed down, and extends substantially to the top of the precipitator cells. Because of the number of parallel plates in the cells, any water flowing through consequently,

them flows out of the cells substantially vertically so that none of the water can flow into the ventilating system which is preferably shut down during the washing operation.

Addition-ally, it may be observed that the power-pack is well out of the gas stream and, does not interfere appreciably with the airflow. Moreover, this gas-flow must pass substantially entirely through the precipitating cells because .the edges of the cell casings rest upon the members of the framework which are made to snugly, and preferably, gas-tightly fit the inside of the casing 2. If desired,-a further compressible strip may be secured to the door '22 opposlte the front side 48 of the framework.

While I have described-my invention in the preferred form, it is quite obvious that many equivalents of the features described may be employed and other features added, as, for example,- the windows I46 by means of whichthe interior of the casing may be observed, and an aperture M8 in the framework through which a conductor A hose may then be inserted casing being normally closed except for a pair of openings adapted for connection to said con-. duits; open-ended, electrical precipitating means supported in said casing intermediate said openings, said means being constructed and arranged in said casing so that the gas passing from one-of saidopenings to the other must pass through said precipitating means; electrical power-transforming means forenergizing said precipitating means, including a condenser for supplying high potentials to said precipitating means; one of said sides having opening means and closure means therefor for access to said precipitating means, said closure means including a switchoperating means for deenergizing said'electrical means when said closure means is first moved toward open position an amount insufiicient for access to the interior of said casing, said closure means further including protective means for preventing, after operation of said switch-operating means, opening ofsaid closure means for access to the interior of said casing until said condenser has charged.

2. An electrical unit for cleaning ,dust particles from a gaseous stream by electrical precipitation, and adapted especially for insertion into, or as part of, the conduits of a ventilating, or air-conditioning system, or the like, said unit comprising a casing having a top, substantially-verticalsides substantially rectangular in section, and a bottom, said casing being normally closed except for elements defining a pair of openings adapted for connection to said conduits, one of said openings being in proximity to the said top, and the secbeen substantially completely dis- 0nd in proximity to the said bottom; a framework secured in said casing;' electrical precipitat ing means, comprising one or more open-ended cells having substantially vertical dust-collecting electrodes, supported on said framework, said framework and means being constructed and 'arranged in said casing so that the'gas passing from one of said openings to the other must pass through said means; said framework including spaced bars upon which the edges of said cells rest; one of said sides having an opening through which said cells may be inserted or removed; and

'a closure means for the last said opening, in-

cluding a compressible material along its periphery, and fastening means for said closure means for compressing said material against the edges defining the last said opening whereby the closure is made substantiallywater-tight; said casing having a further opening above said precipitating means and closure means therefor whereby when the last said means is open said precipitating means may be washed by means of a hose inserted through the last said opening; and drain means for draining washing fluid said bottom being sloped to said drain means.

3. An electrical unit for cleaning dust particles from a gaseous stream by electrical precipitation, and adapted especially for insertion into, or as for elements defining an upper and a lower opening adapted for connection to said conduits; a framework secured in said casing; electrical precipitating means, comprising one or more openended .cells having substantially vertical dustcollecting electrodes, supported on said framework, said framework and means being constructed and arranged in said casing so that the gas passing from one of said openings to the other must pass through said means; said framework including spaced bars upon which edges of said cells rest and can slide; one of said sides having an opening-through which said cells may be inserted or removed; and a closure means for the last said opening including a compressible material along its periphery; and fastening means for said closure means for compressing said material against the edges defining the last said opening whereby the closure is made substantially water-tight; said casing having a further opening above said precipitating means and closure means therefor whereby when the last said means is opened said precipitating means may be washed by means of a hose inserted through the last said opening, and drain means for draining washing fluid; encased electrical power-transforming means in said casing above and for said precipitating means, and protective means for deenergizing said electrical means when said closure means are opened.

4. The structure of claim 2 characterized by the last two said openings being in the last said side of said casing, and the said closure means for the last said openings being interlocked so that the second said closure means must be opened before the first said closure means can be opened, and the first said closure means must be closed before the second said closure means can be closed; electrical power-transmitting means for said precipitating means; and protective means on said second closure means for deenergizing said electrical means when the second said closure means is opened.

5. An electrical unit for cleaning dust particles from a gaseous stream by electrical precipitation, and adapted especially to be part of, and connected to the conduits of, a ventilating or airconditioning system, or the like, said unit comprising a casing having a top, substantially-vertical sides, and a bottom, said casing being normally closed except for elements defining a pair of openings adapted for connection to said conduits, one of said openings being in the upper part of said casing, and a second in proximity to said bottom; an open framework secured in said casing above said second opening; electrical pre-- cipitating means comprising one or more openended cells each having ionizing means and substantially vertical dust-collecting electrodes to be disposed successively in the direction of gas-flow;

said framework comprising members upon which either end of said cells may rest, thereby supporting said cells; said casing having openings and closures therefor, and said framework and said precipitating means being constructed and arrangedin said casing so that said cells may be reversed, so that gas passing from either one of said openings to the other will pass successively first through the said ionizing means and then through said dust-collecting electrodes;

6. An electrical unit for cleaning dust particles from a gaseous stream by electrical precipitation, and adapted especially to be part of, and connected to the conduits of, a-ventilating or airccndltioning system, or the like, said unit comprising a casing having a top, substantially-vertical sides, and a bottom floor, said casing being normally closed except for elements defining a pair of openings adapted for connection to said j conduits, one of said openings being in the upper part of said casing, and the second in proximity to said bottom floor; an open framework secured in said casing above said second opening; electrical precipitating means comprising one or more rectangular-prismatic, open-ended cells each having ionizing means and substantially vertical dust-collecting electrodes to be disposed successively in the direction of gas-flow; said framework comprising members upon which either end of said cells may rest, thereby supporting said cells; said casing having openings and closures therefor, and said framework and said precipitating means being constructed and arranged in said, casing so that said cells may be reversed, so that gas passing from any one of said openings to the other will pass successively first through said ionizing means and then through said dust-collecting'electrodes; said casing having a further opening and closure means therefor above said precipitating means whereby when the last said closure means is open said precipitating means may be washed by means of a hose inserted through said last opening, said bottom floor being provided with a drain and having a surface sloping toward said drain.