US2615529A

US2615529A - Electrostatic precipitator

Info

Publication number: US2615529A
Application number: US52329A
Authority: US
Inventors: Roland L Lincoln
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1948-10-01
Filing date: 1948-10-01
Publication date: 1952-10-28
Anticipated expiration: 1969-10-28

Description

Oct. 28, 1,952 R. l.. LINCOLN 2,615,529

ELECTROSTATLPC PRECIPITATOR Filled Oct. l, 1948 5 Sheets-Sheet l INVENTOR.

` 27o/qnd L n-veo /11 Oct. 28, 1952 R. L. LINCOLN 2,615,529

ELECTROSTATIC PRECIPITATOR Filed oct. 1, 1948 5 sheets-sheet 2 Isa/venan' Poland L. Minto/lz I gawd M Oct. 28, 1952 R. L. LINCOLN 2,615,529

ELEcTRosTATIo PRECIPITATOR Filed Oct. l, 1948 5 Sheets-Sheet 5 Oct. 28, 1952 R. l.. LlNcoLN 2,615,529

ELEcTRosTATIc PRECIPITATOR 'Filed oct. 1, 194s 5 sheets-sheet 4 Oct. 28, 1952 R. LINCOLN ELECTROSTATIC PRECIPITATOR 5 Sheetg-Sheet 5 Filed 0G12. l, 1948 30 Lr -ff Uowney Patented Oct. 28, 1952 UNITED STATESPATENT ortica ELECTROSTATIC PRECIPITATOR Roland L. Lincoln, Dover, Mass., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 1, 1948, Serial No. 52,329

l2 Claims.

. in a gas to be cleaned are givenelectrostatic charges and in the collector chamber, the charged dust particles are caused to be. attracted to,` and to precipitate upon, dust collecting electrodes.

The dust collecting electrodes usually are closely spaced plates, alternate of which are grounded and the others of which are insulated from the grounded ones. A differencev of potential is established between the grounded and the insulated plates for establishing an electric'eld therebetween. Usually the dust Iparticles are given positive electrostatic charges in the ionizing chamber, and the insulated collector plates are positively charged so that the charged dust particles are attracted to the grounded plates. Experience has shown, however, that although most of the dust is attracted to the grounded plates, some is attracted to and adheres to the insulated plates. Some dust also precipitates upon the ionizer electrodes. adheres thereto and for efficiency in operation has to be removed at intervals.

The most widely used method of cleaning the ionizer and collector electrodes is by washing them with a liquid such as water or a light oil sprayed through nozzles upon the electrodes. The collector plates have substantial areas and eX- tend substantial distance in the direction of gas flow and, due to this and to their close spacing, it is diflicult to project cleaning fluid with sufficient force upon all of their surfaces for providing adequate cleaning. For adequate cleaning, the liquid should exert a scouring or wiping eiect upon all surfaces of the collector plates.

The conventional washing systems have liquid spray nozzles which in some cases, are fixed and in some cases are movable, but in either case are so arranged that most of the liquid which is sprayed strikes the plate surfaces at angles so that its force is dissipated through impact. Fur- The dust precipitated on the electrodes thermore, the washing action is not sufficiently effective over those surfaces of the plates which are furthest removed from the spray nozzles.

Another disadvantage of the conventional washing system is that the spray headersr and the piping and other components connected thereto, vare in the gas stream when not in use, and interfere with the gas flow and, as a result, with the collection efficiency.

This invention overcomes the' described' disadvantages of the prior electrostatic precipitators, i

and has other advantages, which will be described, over the prior precipitators.

A feature of this invention is that the spray nozzles are arranged to be moved horizontally along the collector plates so that each nozzle sprays liquid between adjacent plates and parallel to their surfaces thereby effectively scraping the deposited dust therefrom. i

Another feature of this invention is that the spray nozzles are arranged to be moved horizontally across the gas entering and the gasleaving ends of the collector plates, the nozzles at the upstream ends of the platesspraying liquid Atowards the downstream ends thereof, and the. nozzles at the downstream ends of the plates spraying liquid towards the upstream ends thereof, the two sets of nozzles effectively washing andfcleaning all of the plate surfaces.

Another feature of the inventionis thatgthe spray header carrying the nozzles at theupstream ends of the collector plates also has nozzles which spray cleaning liquid uponjthefionizer electrodes.

Another feature 0f this invention is that'.` during the periods the precipitator is cleaning. gas, the spray headers and their pipes and other components are completely removed from the gas stream.

Another feature of this invention is that an eicient compact electrostatic precipitator is provided which is self-contained in that it encloses its own separate ionizing, collection, and washing apparatus, with louvres in its upstream, Hand downstream ends which are closed when theelectrodes are washed, and which is .adapted to be operated in series with .other similar precipitators so that one at a time can be removed=from service for cleaning while the Othersremain` in service. A V' Another feature of the invention is that the collector chamber comprises a plurality of similar, compact collector cells which are easily removed and installed, and which can readily be stacked one above the other and/or one alongside the other` for providing any desired size of collector chamber.

An object of the invention is to provide a compact, self-contained electrostatic precipitator having its individual ionizing electrodes, collector electrodes, and electrode washingr mechanism whereby it can be combined with other similar precipitators for providing a dust collection system of any desired size.

Another object of the invention is to provide an improved electrode washing system for the electrodes of an electrostatic precipitator.

Another object of the invention is to provide electrode washing components for an electrostatic precipitator which are isolated from the gas stream when the precipitator is operated to clean a gas.

The invention will now be described with reference to the drawing of which:

Fig. 1 is a perspective view of an electrostatic precipitator embodying this invention, with a portion at the front and one side removed for illustrating the arrangement of the inner components;

Fig. 2 is a plan View, in section, of the precipitator, the section being taken along the lines 2-2 of Fig. 3; I

Fig. 3 is a side elevation, in section, of the precipitator, the section being taken along the lines 3-3 of Fig. 2;

Fig. 4 is a section, of the precipitator, the section being taken along the lines d-- of Fig. 3, and

Fig. 5 is a front elevation corresponding to Fig. 4 but illustrates the position of the electrode washing equipment removed from the gas stream when not in use.

The precipitator as illustrated has a cubical shape with a structural steel frame I!! and sheet metal sides I I, two sides being open for the entry and exit of gas. The gas entering end of the precipitator has the plurality of spaced, inlet louvres I2 therein which are interconnected by the linkage I5 so that they can be simultaneously adjusted to open or closed positions.

The structural steel frame I'I extends vertically at the longitudinal and transverse center of the precipitator and has the spaced outwardly extending shelves i8 thereon. The opposite sides of the frame-work of the precipitator have the shelves I9 thereon which are aligned with corresponding shelves I8. The collector cells 26 are placed on the shelves I8 and I9. ln the embodiment illustrated, the collector chamber contains twelve cells arranged in two vertical rows with six cells in each row stacked one above the other. The collector cells are similar and are of the type disclosed in the E. L. Richardson Patent No. 2,535,696. The cells are self-contained, are compact and light in weight, and can easily be removed from, and installed in, the collector chamber, as for servicing or replacement. As illustrated most clearly by Figs. l, 2, and e, the collector plates 2I of the cells 2S are arranged vertically, the plates of each underlying cell being in vertical alignment with the corresponding plates or the similar cell located above it.

Located downstream of the inlet louvres I2 is the ionizing chamber 24 which contains the plurality of vertically extending, relatively large,

tubular ionizer electrodes between which are suspended the ionizer wires 23 carried on the ends of the supports 25, the supports 2G being attached to the bars 2l, which in turn are supported by the insulators 28. This ionizer electrode arrangement is conventional.

The equipment for washing the ionizer electrodes and the collector plates will now be described. Located between the ionizer electrodes and the collector cells are the upper and lower, threaded rods and SI respectively. These rods are located above and below respectively, the collector chamber, and are completely out of the gas stream passing between the ionizer and collector chambers.

The upper and lower threaded rods and 36 are arranged between the collector cells 2U and the outlet louvres I4, these rods also being out of the gas stream, the upper rod 35 being in horizontal alignment with the upper rod 30, and the lower rod 35 being in horizontal alignment with the lower rod 3I.

The rod 3D has threaded thereon the ntting 38 which is attached to the upper, closed end of the liquid header 3B. The closed, lower end of the header 39 has attached thereto the fitting IQ which is threaded on the lower rod 3l.

The header 39 has the spaced downstream spray nozzles l-l, two of which face the upstream ends of the plates of each collector cell 2U. The header 3S also has the spaced, vertically aligned, upstream, spray nozzles 4I, each of Which are arranged to wash the entire surfaces of the ionizer electrodes.

The ntting :l5 is threaded onto the downstream, upper, threaded rod 35 and is attached to the upper, closed end of the liquid header IIB. The fitting 67 is attached to the lower, closed end of the header 4S, and is threaded onto the lower, downstream, threaded rod 36. The header 4B has the spaced, vertically aligned, nozzles i8 extending upstream therefrom, two of these nozzles being in alignment with the downstream ends of the collector plates of each collector cell 2U.

The upstream header 39 has the pipe fitting 50 extending therefrom, and which is threaded into the swivel pipe' connection 5I which, injturn, is threaded on the upper end of the pipe 52. The lower end of the pipe 52 and the lower end of the pipe 53 are connected together through a swivel pipe fitting 54. The upper end of the pipe 53 is connected to the liquid supply pipe 54.

The downstream header 4B has the pipe fitting 55 extending therefrom, and which is threaded into the swivel pipe connection 56, which, in turn, is threaded on the upper end of the pipe 57. The lower end or" the pipe 5l, and the lower end of the pipe 5S are connected together through a swivel pipe connection 59. The upper end of the pipe 58 is connected to the supply pipe 5d.

Arranged at one side of the gas passage through the precipitator, the left-hand side facing Figs. l, 3, and 5 of the drawing, is the electric motor 55 which is connected to the speed reducing gear mechanism GI by the belt 62. The mechanism 6I has a sprocket 63 with which the chain 64 meshes. The chain @d extends around and meshes with the sprocket G5 on one end of the upper threaded rod 35, extends around and meshes with the sprocket 65 cn the corresponding end of the upper, downstream, threaded rod 35, then meshes with a similar sprocket on the corresponding end of the downstream, threaded rod 3'6, and then meshes with the sprocket 58 on the corresponding end of the upstream, lower, threaded rod BI.

T'Ihegchainil "is an nendless chain, and as it .is

'rotated throughthe gear-reducing mechanism 6I by themotor 60, fit frotates simultaneously the threaddgrods A30,531, 35, and 36. vThis rotation .of the threaded rods causeshorizontal movev:nient ofthe 'ttings-38 and Vl!!! attached to the upstream headerf39,van`d the downstream'ttings Cl-a'nd'tl attache'dtothe downstreamheader d'5,

{causing corresponding horizontal movement of the'twoheaders. l Y

"Normally, when the electrostatic precipitator -isoperating tooleangas, the inlet louvres l2 and lthe-outlet louvres `l'4 -willbe open in the posi- -tions illustrated-most clearly by Fig. 13. At this 'time, theheaders will be in the-passage 'l0 v(Fig.

f4), -Whichis atthe left hand side -of the gas K passage through vthe precipitator, in lthe position -illustrated by .the full lines of Fig-5. The dashed L)lines .illustrating vthe upstream header kand the .piping-of Fig. f5, 4show another position of the 'header when it is l:being used to spray :cleaning liquid between the-collector plates and on the ioniz'er-electrodes. K

iFigs. 11,12, iand-4l illustrate one position of the upstream v.and -downstream headers when they =arebei`ng used to clean the-electrodes.

lshould be understood" that the 'invention is not limited tothe exact apparatus and arrangement of apparatus illustrated, las modifications therefrom may be suggestedby those skilled in the art without departure from' the essence of the in.-

` vention.

What is claimed-is: 1.*An' electrostatic precipitator comprising a casinghaving a gas inlet and a gas outlet and a `lpai'ro'f vertical sides, a plurality of substantially vertically extending, r spaced apart collector plates supported in said .casing betweensaidinlet and '.outletland .parallel said sides, said .casing having an open space between one of said vertical sides `and `the outermost ofsaid plates at one side of :said plates whichis out of alignment with said inlet :and plates, a .substantially vertically extendingliquid header lhaving .a plurality of spray nozzles .for .spraying liquid in between adjacent .'ofsaid plates, and means for moving said header .substantially horizontally back and forth along said plates yfor washing same, and for moving s aid header into said space following the washingoffsaid plates, said header 'whenin said space :being out of the gas streamflowing from said finlet .between 'said plates.

` l2. An'velectrostatic precipitator having `a casing .I 'The `sump'80'is1provided in 'the .lower .portion fof vtheprecipitator fand is adapted to be drained through the drainfconnection 8|.

lAftera period of operation, longenough to have 'caused-enough"sufficient dust to have beencollecte'dthat cleaning -is required, :then the high voltage current .applied to the ionizer and collector electrodesis-removed,'and theinlet louvres l2 'and the outletllouvres I4 are closed. This can ibe done manually Vor'by suitable automatic con- 'trols. The cleaning liquid which may be a light "oil vas is commonly fused lfor .cleaning the elec- :trodes of lelectrostatic precipitators is supplied into the pipe 54. The energizing circuit of the vmctortis thenclosed, causing it to rotate. This causes the chain 56'4 lto revolve, and .causes fthe headers 39 land dl to move from the position, shown vby the full vlines cf Fig. 5,horizontally 'towardsthe right-hand side of the precipitator.

' This causes theupstream nozzlesll of the header 39 to wash the dust adhering to the ionizing electrodes therefrom. The downstream nozzlesy v i0 of the upstream header 3'9 moverslowly across the upstream lends of the 'collector plates 12| r of vthe-collector .cells 20, and spray the cleaning. liquidin between the .plates Vparallelto their sur-v faces, so .thatthe energy ofthe spray is expended having .a gas inlet and a gas outlet `and a pair *of vertical Sides, .a plurality of substantially vertically extending, :spaced apart collector'plates .supported in said casing between said inlet and outlet and parallel said sides, Vsaid casing havin'scouring or wiping 'the plate surfaces. Since the spray from the downstream nozzles vllllzof the yupstream header 39 may not bel eective `to completelyclean the downstream portions ofthe collector plates, the vupstreamnozz'les 48 .of the downstream header '46 spray liquid into the spaces l between the downstream `ends -of .adjacent col- Ilector plates, and parallel to the `plate surfaces asiin the case of the nozzles 40, thus scouring or wiping Vthe ldownstream .portions of `the plates.

The swivel .connections 5|, 54, 56, and .59 Eper-` mit liquid tobe 'supplied'to the headers' through i their supply piping, as they 'are :moved back and .forth during'the washing operation. i

.In one actual installationv embodying this invention, it `was found that the plates could be adequately cleaned by moving the spray headi ers from their startling position outside the gas .stream,.;past the surfaces ofthe D1aBS,-andback A"again to their starting position. While one embodiment :of the invention has vbeen described for the purpose of illustration, it

in'g .'anopen .space :between one :of said vertical :sidesand the outermost of .said plates vat one ,side of said plates which is out tof alignment with :said-inletand plates, a substantially vertically 'extending liquid header havinga plurality .of .spray .nozzles for spraying liquid in .between adjacent of said plates, said header having ends extending above and below said plates, and means ...at said ends ofv said header for moving same sub- `stantially .horizontally back and forth along said platesv for washing same, and for .moving said header into said open space when the washing is completed, said .header when in .said space being out of the :gas stream owing from said inlet .between said plates.

i i3.An electrostatic precipitator comprising a .casing having open ends, one forming a gas inlet and the other forming a gas outlet, l.ionizer electrodes in said casing adjacent said inlet,

a .plurality of substantially vertically extending collectorplates insaid casing between said elec- "..trodesand saidoutlet, a substantially .vertically 1.ex`tending liquid Jheader movable between said .electrodes and said plates, said lheader having a plurality of downstream nozzles arranged to spray 'liquid `.between said collector plates, 'and having a :plurality of upstream .spray nozzles arranged to .spray .liquid 'upon said electrodes, and means for moving said headersubstantially horizontally between. said electrodes. and said plates.

.4..An1el'ectrostatio precipitator comprising a .casing .having open'ends, one formingla gas inlet .and theother forming a gas outlet,'ionizer electrodes .in said casingadjacent said inlet, a pluvirality `of substantially vertically extending col- ;lector fplatesin'rsaid casing between 'said electrodes and said outlet, a substantially vertically extending liquid header movable Ybetween said `electrodes and .said plates, said vheader having. a

pluralityof downstream nozzles arranged to spray liquid between said collector plates, and having .aplurality of'upstreamspray nozzles'arranged to spray vliquid .uponsaid electrodes, said header having ends extending; above and below vvsaid plates, and means at said ends, osaidheader for moving said header substantially horizontally between said electrodes and said plates.

5.*An electrostatic precipitator comprising a casing having open ends, one forming a` gas yinlet and the other forming a gas outlet, said casing having an open space therein at one side thereof, ionizer electrodes in said casing adjacent said inlet, a plurality of substantially vertically explates, and having a plurality of upstream spray nozzles arranged to spray liquid upon said electrodes, and meansfor moving said header substantially horizontally between said electrodes and said plates for washing said plates, and for moving said header into said space when the washing is completed.

6. An electrostatic precipitator comprising a casing having open ends, one forming a gas inlet and the other forming a gas' outlet, said casing having an open space therein at one side thereof, ionizer electrodes in `said casing adjacent said inlet, a plurality of substantially. vertically extending collector plates in said casing between said electrodes and said outlet,y asubstantially vertically extending liquid header movable 'between said electrodes and said plates, said header having a plurality of downstream nozzles' arranged to spray liquid between said collector plates, and having a plurality ofupstream spray nozzles arranged to spray liquid upon said electrodes, said header having-ends extending above ,8 l i `plates and said outlet and having a plurality of upstream spray nozzles arranged to sprayvjliquid between said plates, and means. fori moving said 'headers substantially horizontally.-along- Hsaid ,plates i precipitator vcomprising a 9. An electrostatic msnghaving openv ends, one forming a* gas inlet y and the other forming a gas outlet, ionizer elecrodes in said casing adjacent said inlet, aplurality of substantially vertically extending coli lector plates in said casing between said electrodes and said outlet, a substantially vertically extending liquid header movable between said, electrodes and said plates, said-header having a; plurality of l downstream Ynozzles arranged to spray liquidfbetween said collectorplates, aseeond substantially vertically extendingA header movable between said plates and said outlet and vhavinga plurality of upstream spray nozzles arranged rto spray liquid between said plates, said headers having ends extendingabove andv below platesg and meansat y said ends of said headers-for moving said headers substantially horizontally along said platea.

` outlet and having a plurality of upstream spray and below said plates, and means Vat said ends of said header for moving'said header substantially horizontally between said electrodes and said plates for washing said plates, and for moving said header into said space when the washing is completed. Y u

7. An electrostatic precipitator comprising a casing having open ends, one forming a gas inlet and the other forming a gas outlet, ionizer-electrodes in said casing adjacent said inleta plurality of substantially vertically extending collector plates in said casing between said electrodes and said outlet, a substantially vertically extending liquid header movable between said electrodes and said plates, said header having a plurality nozzles arranged to spray liquid between said plates, and means for moving said headers substantially horizontally along said plates for washing said plates, and for moving said headers into said space when the washing is completed.

ll. An electrostatic precipitator comprising a casing having open ends, oneforming-a-gas inlet and the other forming a gas outlet; said cas- -ing having an open space therein at one `side thereof, ionizer electrodes in said casing` adjacent of downstream nozzles arranged to spray liquid n rality of substantially vertically extending col-- lector plates in said casing between said electrodes and said outlet, a substantially vertically extending liquid header movable between said electrodes and said plates, said header having a plurality of downstream nozzles arranged to spray liquid between said collector plates, and having `a plurality of upstream spray nozzles arranged to spray liquid upon said electrodes, a second substantially vertically extending header movable between said said inlet, a plurality of substantially vertically extending collector plates in said ycasing Vbetween said electrodes and said outlet, a substantially vertically extending liquid header movable betweensaid electrodes and said plates, said header having a plurality of downstream vnozzles arranged to spray liquid between said collector plates, a second substantially vertically` extending header movable between said plates and said outlet and having `a plurality of upstream spray nozzles arranged to spray liquid betweensaid plates, said headers having ends'extending above and below said plates, and means at ysaidends of said headersfor moving said headersisub'stantially `horizontally along said plates forzwashing said plates, and for moving said headers into said space when the washing is completed.-v v

l2. An velectrostatic precipitator comprising a casing having open ends, one forming a gas inlet and the. other forming a'gas` outlet, vsaid vcasing having an open space therein at one side thereof, ionizer electrodes in said casing adjacent said inlet, a plurality of substantially vertically extending collector plates in said casing'betwecn said electrodes and said outlet, a substantially vertically extending liquid header-movable between said electrodes and said plates, said header having a plurality of downstream nozzles arranged to spray liquid between said collector plates, and having a plurality of upstream sp-ray nozzles arranged to spray liquid upon said electrodes, a second substantially vertically extending header movable between said plates and said outlet and having a plurality of upstream spray nozzles arranged to spray liquid between said plates, and means for moving said headers substantially horizontally along said plates, for washing said plates, and for moving said headers into said space when the washing is completed.

ROLAND L. LINCOLN.

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

UNITED STATES PATENTS Number Name Date Craft Apr. 8, 1941 Peggv Nov. 2, 1943