US2949168A - Electrical precipitator apparatus of the liquid spray type - Google Patents

Description

Aug. 16, 1960 F. v. PETERSON ELECTRICAL PRECIPITATOR APPARATUS OF THE LIQUID SPRAY TYPE 4 Sheets-Sheet 1 Aug. 16, 1960 ELECTRICAL PRECIPITATOR APPARATUS oP THE LIQUID SPRAY TYPE Filed Deo. s, 1956 4 Sheets-Sheet 2 To .4.6. SUPPLY INVENToR. F/vyol l/ Rahman Aug. 16, 1960 F. v. PETERSON ELECTRICAL PRECIPITATOR APPARATUS OF THE LIQUID SPRAY TYPEI` Filed Dec.

4 sheets-sheet :s

U il INVENToR F/aya/ l( )31615.40

Aug. 16, 1960 F.A v. PETERSON ELECTRICAL PRECIPITATOR APPARATUS OF THE LIQUID SPRAY TYPE Filed Deo. 3, 1956 4 Sheets-Sheet 4 NVENTOR. F/ay/ V Bhutan BY )a u) ELECTRICAL PRECIPTATGR APPARATUS F 'EI-m LIQUID SPRAY TYPE Floyd V. Peterson, 20728 Ventura Blvd., Woodland Hiiis, Calif.

Files nec. 3, 1956, ser. No. 625,752

1e claims. (ci. isa- 7) Generally speaking, the present invention relates to electrical or electrostatic precipitators of the liquid spray type, cooperable for removing particles of foreign material from gas. More particularly, the present invention relates to an improved precipitator of this general type adapted to remove particles of foreign material, such as dust particles, suspended solids, foreign gases, or the like, from air or any other desired gas to be cleaned.

A primary object of this invention is to provide a precipitator system of the liquid spray type which will operate with a high degree of etciency, and in general continuously with fail-safe operation in the process of cleaning gases.

Another object of this invention is to provide a precipitator system of said type which will be non-clogging and self-cleaning during continuous operation so that its operation will not be interrupted or its efficiency impaired by precipitated debris.

Another object of this invention is to provide a precipitator system of the liquid spray type which is reasonably simple to construct relative to the general typel and capacity of the gas cleaning operation to be performed.

A further object of this invention is to provide for a certain degree of cooling as well as air cleaning in connection lwith air conditioning.

Other and allied objects will become apparent to those skilled in the art after careful study of the invention as disclosed herein.

ln general, the liquid spray type electrical precipitator is a system economical to construct and it is conducive to continuous operation at high efficiency. Also, it offers some other advantages over conventional electrostatic precipitators with plate type collector electrodes. However, the liquid spray type electrical precipitator has never come into general usage. This is apparently due to certain impairments in the operation of prior art systems of this type, with particular reference to undesirable electrical flash-overs within the precipitator assemblies.

The invention disclosed herein, provides an arrangement for obviating undesirable electrical ilashovers and at the same time it initiates a system that will operate at a high degree of efficiency on a continuous basis.

Generally speaking, this invention comprises the following component parts:

(l) A gas duct means cooperable to transmit gas therethrough, and included in said duct means an input portion, an intermediate mixing portion having special inner and outer wall construction, and an output portion.

(2) First electrostatic ionizing means consisting of alternately spaced discharging and non-discharging electrodes, located at the input portion of said gas duct means for the purpose of ionizing the foreign particles in the gas to be cleaned.

(3) Liquid spray chamber having special inner and outer wall construction, with said chamber located upon gas duct means in a manner to be generally out of line and latterly offset with the same; with liquid spray heads located within or upon said spray chamber, and with second electrostatic ionizing means consisting of alternately spaced discharging and non-discharging electrodes located within said liquid spray chamber intermediate with spray heads and gas duct means; wherein the spacial paths between discharging and non-discharging electrodes of the ionizing means are rendered electrically nonconductive, regardless of type or density of liquid spray, by means o electrical insulation applied at the exterior surface of the non-discharging electrodes.

(4) Fan arrangement or other mechanical means for forcing or drawing the gas to be cleaned through said gas duct means.

(5) Liquid spray condensing and drain away means at output of gas duct means.V

(6) Power supply means fo-r providing two sources of direct current in the approximate voltage range of 10,000

y to 15,00() Volts, for application to the ionizing means.

(7) An arrangement providing a liquid transmissive but electrically non-transmissive path to ground for liquid that may be incidentally condensed or for spray `droplets that may fall to the bottom of gas duct means when the overall precipitator system is in operation.

(8) Associated parts or assemblies for facilitating the precipitator operation including spray liquid heating device, vibrating or rapping arrangement for removing debris from non-discharging electrodes, a liquid transmissive but electric current non-transmissive tank assembly for supplying spray liquid under pressure at electrical voltages above ground potential to precipitator systems, spray type apparatus for cleaning the electrodes of 4an ionizing means, and special insulating apparatus for electrical leads passing through walls of a precipitator. Y The provision of suitable electrical insulating material on the exterior surface of the non-discharging electrodes of the ionizing means precludes against voltage breakdown in the spacial path between the discharging and nondischarging electrodes of the ionizing means. Also, providing said insulation of a material having a high dielectric constant makes possible more intense ionizing fields so the ionizing process is thereby facilitated.

Furthermore, the art of so electrically insulating the` non-discharging electrodes incorporated in the liquid spray ionizing means, together with the provision of specially constructed double walled intermediate mixing portion and liquid spray chamber means, wherein the inner walls of the same are properly electrically insulated and/ or biased as set forth in this invention (described hereinafter in reference to the drawings) Vare cooperable to an arrangement whereby the path of electricalV conduction of the power supplied to the liquid spray ionizing means is substantially coniined to the moving electrically charged particles within the precipitator enclosure from the d-ischarging electrode means, through the liquid spray chamber', thence through the intermediate mixing portion to the output portion of the gas duct means, thence to the non-discharging electrode means, completing the electrical circuit. v

Means were thus devised to confine said path of electrical conduction within the limits stated above, in the present invention, in order to overcome certain difiiculties encountered with prior art electrical precipitator systems of the liquid spray type in 'which there exists virtualV electrical short circuiting conditions. ln explanation, these precipitator systems are provided with bare (uninsulated) non-discharging electrodes in the liquid spray ionizing means. Therefore, when normally suitable ionizing potentials and liquid sprays, aroused with said systems, electrical flashovers occur in the spacial path between the discharging and non-discharging electrodcsy of the liquid spray ionizing means. Y v

Another virtual short-circuiting path inherently common with the prior art systems isfrom the discharging` electrode means, of the liquid spray ionizing means, through the particles of spray liquid directly to the inner walls of the precipitator enclosure.

The methods and means for obviating the short circuiting conditions inherently associated with the prior art systems, together with the details of the other improvements and advantages of -this invention lwill become more apparent hereinafter by reference to the accompanying drawings.

The spray liquid may be ordinary tap water which is suitable and desirable in most cases because of its cheapness and availability, yalthough any spray liquid may be used unless unsuitable for some reason such as being highly volatile or explosive.

Furthermore, water is used in air conditioners or coolers of the evaporative type. The precipitator of the present invention will iit lright in with this type of air conditioner. The air is cooled in the precipitator as it passes through and mixes with the water spray when the water used is Iat a moderate temperature. The heat absorbed from the air is largely drained away with the condensed spray and precipitated debris. Furthermore, the present invention removes moisture from the air being cooled, which is highly desirable under many circumstances, and especially with evaporative type coolers as used in air conditioning.

Fig. l is a view showing one illustrative embodiment of this invention with portions thereof in vertical section, with certain portions removed for clarity, and with ,certain portions shown in diagrammatic and/or schemail? form;

Fig. 1A is a view (larger in scale than Fig. 1) of the form of the invention shown in Fig. 1 taken in the direction of the arrows 1A-1A in Fig. l and with certain portions removed for clarity.

Fig. 1B -is a view (larger in scale than Fig. l) of the form of the invention shown in Fig. 1 taken in the direction of the arrows 1B--1B in Fig. l and with certain portions removed for clarity.

Fig. 2 `is a view generally similar to Fig. l, but illustrating, .in partial, diagrammatic and/or schematic form, a modified version of the invention;

Fig. 2A is a view (larger in scale than Fig. 2) of the item 31 shown in Fig. Zand taken substantially in vertical section therethrough; and

Fig. 3 is a View generally similar to Fig. 1 and Fig. 2 b ut illustrating, in partial diagrammatic and/or schematic form, another modified form of the invention.

.Referring to Fig. l, a precipitator enclosure is made up of four tubular sections or chambers 1, 2, 3, and 4 respectively. Sections 1, 2, and 3 yare of an electrical insulating material such as phenolic, treated Vrnasonite or any other good insulating material of reasonable strength, suitable temperature characteristics, and preferably shatterproof. Sections 1, 2, and 3 are surrounded by an electrically grounded metallic shield 5 which is spaced from said sections by electrical insulators 6. Section 1 4 is of metal and is electrically grounded.

Section 1 is the input section wherein the air or gas to be cleaned enters the precipitator and where the foreign particles are electrically charged. Section V2 is the liquid spray and foreign particles mixing section. Seotion 3 confines -the -area wherein the liquid spray is electrically `charged. The electrically charged and mixed liquid spray particles and foreign particles are condensed within section 4 and drained away in liquid form.

The gas to be cleaned may beforced through sections 1, 2,.and 4 by the gas pressure atthe input of the precipitator or it may be'drawn lthrough by a `mechanical fan7 Ilocated at the outputofsection `4. When thegas is drawnthrough thevprecipitator by means of a fan it is desirable=to provide holes or openings `8A near the bottom of section 3. `Air-.willrbe drawn through these openings .andfhelp to'carry the liquid sprayil1`to section 2. It `is ,alsodesirablegto provideA rather. small` openings such 4 as 24 and 24 in the insulating material 22 and 23 which supports the ends of precipitator sections 1 and 4 respectively. The air flowing through these openings will help keep the insulation clean on the interior part of the preoipitator.

As the gas to be cleaned passes through section 1 the foreign particles in the gas are given an electrical charge by a charging arrangement consisting of `a plurality of tine wires 8 spaced between grounded metallic electrodes 9. See sectional View lA-lA. The fine wires 8 are insulated above ground by attachment to insulators 47, which are not shown in Fig. l 4for reasons of clarity. They are given an electrical charge in the neighborhood of 10,000 to 15,000 volts D C., above ground potential, by power supply l1t). This charge is applied through insulator 11 and may be positive or negative with respect to ground but must be opposite in polarity to the elec trical charge applied to the electrodes used in charging the liquid spray particles, as hereinafter explained.

Resistor 12 is provided to limit the current in case of a short circuit between wires 8 and electrodes 9.

Since the grounded electrodes 9 will normally attract and collect foreign particles which impair the eiciency of the electrical charging action on the foreign particles it is desirable to keep electrodes 9 as clean as possible. Sectional view lA-IA shows an arrangement for continuously vibrating electrodes 9 to preclude against the collection of debris. As indicated, these electrodes are attached to two vertical members 42 which are flexibly supported at the top lby means of springs 43 and 44, `and caps 45. Magnets 46 which are operated by alternating current act upon caps 45 and produce a vibrating action which is transmitted to electrodes 9 through vertical members 42. The same effect might be accomplished `by providing automatically operated hammers which intermittently rap caps 45.

Spray heads 13 located in the lower part of section 3 emit the liquid spray into section 2. Any liquid spray that is condensed in section 2 falls back into section 3 and is drained away through drain pipe 26 located near the bottom of section 3. Spray heads 13 are supplied spray liquid from an external source at some pressure in the neighborhood of 30 to `several hundred pounds per square inch depending upon the typeof spray head used and the nature of the foreign particles to be precipitated. A tank 15 (or other ysuitable means) may be provided for heating the spray liquid before it is supplied to the spray heads. The heating will facilitate the dispersing of the spray liquid.

As the liquid s pray passes through section 3 it encounters an electrical charging arrangement consisting of tine wires 17 spaced between metallic electrodes 18 which are provided with electrical insulation 19 to withstand a working voltage of 15,000 volts D.C. or more. The electrodes 18 are electrically connected together and grounded externally of the precipitator enclosure as indicated .in sectional view 1B1B. This insulating and grounding arrangement is provided in order to preclude against electrical tiashovers between tine wires V17 and electrodes 18 when a high enough voltage is used to provide a strong electrostatic field between tine wires 17 and electrodes 18. Actually, since the dielectric constant of an insulating material is generally greater than air it will increase the lines of elestrostatic flux throughwhich the liquid spray passes and thus aid in the electrical charging action on the liquid spray.

The tine wires 17 are given an electrical charge of approximately 10,000 to 15,000 volts D.C. above ground potential by power supply `10 which voltage is applied through insulator 20. The electrical charge applied to tine wires 17 may be vpositive or negative in respectto ground but Vmust be opposite in polarity to the voltage applied at insulator 11 for charging the foreign particles in the gas to be cleaned.

Since electrically charged liquid spray ,particles will cadres tend to collect on insulation 19 and somewhat nullify the electrostatic eld between line wires 17 and electrodes 18 the insulating material should be treated or painted with a material that has little ainity for the liquid spray used, such as a silicone type paint when the spray liquid is water.

As the air orgas to be cleaned passes through section 2 of the precipitator the electrically charged foreign particles of the gas attach themselves to the oppositely charged liquid spray particles emitted from section 3 and are carried into section 4 of the precipitator. The liquid spray particles with the attached foreign particles strike againstthe baie plates 28 `and screen 29 in section 4 and are condensed and drained away through drain pipe 30.

Figure 2 shows a vertical sectional view of another possible arrangement of the precipitator system. This arrangement comprises four tubular sections or chambersy anda metallic shield similar to that described in the foregoing for the Figure l version. However, Figure 2 shows the liquid spray charging section at the top of the precipitator instead of at the bottom and depicts certain other features not indicated in Figure 1.

The operation of the system indicated by Figure 2 is also similar to that of the Figure 1 arrangement. As the air or gas to be cleaned passes through section 2 of the precipitator the electrically charged foreign particles attach themselves to the oppositely charged liquid spray particles emitted from section?, and are carried into section 401" the precipitator. The liquid spray particles with the `attached foreign particles strike against the bafe plates 2S and screen 29 in section 4 and are condensed and drained away through drain pipe 30.

Edged blades 17 of some material such as stainless' steel are located between the grounded electrodes in Figure 2 in the liquid spray charging section in lieu of tine Wires as indicated in Figure l.

In order to preclude against ashovers between spray heads 13 and the edged blades 17 when a very tine spray is used the spray heads and pipe line 14 are isolated above ground potential for a working voltage of approximately 15,000 volts D.C. by means of pressure tank 31.

Figure 2A shows a sectional view of pressure tank 31. It is provided with an outer shell 33 of some metal such as steel or high strength copper and an inner lining 34 on the bottom and sides of the tank of an electrical insulating material. The inner lining may be of phenolic, hard rubber, glass, plastic or some other suitable insulating material. Initially tank 31 is partially lled with the desired spray liquid through cap 35 to the necessary level which in general would about one-third full. Valve 32 in line 14 is' closed by means of hook stick operation (to guard against high voltages). Air or some non-explosive gas is then pumped into tank 31 through cap 36 to the desired spray pressure. Y

In operation, valve 32 is opened and the spray liquid is pumped into tank 31 from spray head 38 through pipe line 16 and check valve 37 by some conventional pumping means which yautomatically cuts-olf or reduces the liquid flow rate as the level of the liquid in the tank raises and the desired spray pressure is approached or reached. The spray liquid falls in droplets from spray head 38 into tank 31. Thus pipe line 14 and spray heads 13 are isolated above ground potential by means of the insulation 34 of tank 31, the air or gas Spaces between the liquid drops as they fall into the tank, insulator 40 which insulates pipe line 14 from metal shell 33, yand by means of insulator 44A, which insulates pipe line 14 from the metallic grounded shield 6.

The liquid spray emitted from spreay heads 13 is eleci trically charged in section 3 in a manner similar t0 that described above for the Figure 1 arrangement.

Input lsection 1 of the precipitator is provided with `an electrical charging array consisting of a number of line wires 8 located between grounded electrodes 9 which are provided with insulation 9A for a working voltage of approximately 15,000 volts \D.C. above ground potential. Electrodes 9 are grounded at the exterior of the precipitator in a manner similar to that shown in sectional view 1B-1B of Figure 1. Spray head (or heads) 21 interA mittently spray the electrode assembly 9 and 9A to dislodge collected debris. Spray head 21 is supplied steam, water or some suitable cleaning liquid under pressure from an external source through pipe line 21A. The operation of the precipitator need not be stopped while spray head 21 is emitting the spray or steam for cleaning the electrodes providing spray head 21 is 'located far enough from electrode 8 to prevent flash-over or if it is electrically insulated above ground to prevent Hash-over such as by an insulated tube in the case of steam or by a tank system such as item 31 Where a spray liquid is used. The .insulation 9A will preclude against a Hash-over between electrodes S and 9.

insulating material 22 and 23 is shown relatively thin in Figure 2. It lis provided with holes 24 and 2S for keeping the insulation clean as described in reference to Figure l. Insulators 6A are used for the main mechanical support of the precipitator sections indicated in Figure 2 in lieu of the thicker insulating material as noted in Figure l. The Figure 2 arrangement provides fora more economical method of construction.

The liquid condensed in section 2 of the precipitator is drained away through an arrangement designed to prevent hash-over to ground, which would occur if the liquid were drained away in a continuous stream. The arrangement consists of disk `41A provided with a number of holes to produce a dripping action, chamber 42A made of an insulating material, and metallic drain pipe 43A. The liquid dripping through disk y41A falls through chamber v421A and is drained away through pipe 43A.

The cross-sectional area of output section 4 is purposely constricted in reference to the cross-sectional area of mixing section 2. This method of construction increases the relative velocity in output section 4 for a given quantity of gas or air to be cleaned that passes through the precipitator. The higher velocity of the liquid spray particles striking against the plates 28 and screen `29 aids the process of condensation.

Figure 3 shows a vertical sectional view of a further possible arrangement of the precipitator system. lt comprises four tubular sections orA chambers and a certain amount of exterior metallic shielding as previously described in reference to Figures 1 and 2. Sections 1, 2 and 4 are of metal with sections 1 and 4 electrically grounded. Section 2 is electrically biased in respect to ground potential as hereinafter described. Section 3 may be of an insulating material or it may be of metal and electrically biased with respect to ground potential by its attachment to section 2.

The operation of the system indicated by Figure 3 is similar to that described for Figures 1 and 2. However,

in Figure 3 the spray liquid is emitted in the form *of wet steam from spray or jet heads 13 instead of liquid being sprayed under pressure from spray heads. As the air or gas to be cleaned passes through section 2 of the precipitator the electrically charged foreign particles attach themselves to the liquid spray particles or wet steam particles emitted from section y3 and are carried into section 4. The liquid spray particles or wet steam particles with the attached foreign particles first pass through a water spray in section 4 which is sprayed from spray heads 31 supplied under pressure from an external source through pipe line 32. The water spray condenses the wet steam into larger droplets with the foreign particles attached which strike against baffle plates 2S and screen 29 and are then condensed and drained away through drain pipe 30.

Spray or jet heads 13 are supplied wet steam from an external source through tube 34A made of rubber fabric or some other suitable electrical insulating material.

`asesinas Valye 353A is provided forx controlling the flow of the tau. .L

"The wet steam` niitted from spray ,or iet heads 13 is .f1 o i1. :..l. .t Lus electrically charge by passing through a charging arras-tirent Siillaf tgt atsltsrlbe'd. aber@ fer "he Fleurs 1 vrsitin Qt theprcipltttir'lslstem The foreign p'art'it'zles in the .air or gas to be cleaned are also eletlcally chargedin a'mnne'r that described'a ovCin reference to Figure l.

The metallic shell of 'section Z is electrically biased with respect te gound'potential hy means of potentiometer Abonnee-ted topower supply 1Q.' The connection is made t'h'ru'ghf'insulator QSA." Secfilon'Z'is biaseda't the s arhe p arity ahd'a't'abont thesame voltage that aavlietallh' Wil-@$17! TlilS bis'uill'pftvtafth elet: t'rically C llged spray droplets from migrating to vthe inner surface of the"metallic"shell'of section 2 with a consequent loss of charge and a defeat in the ,purpose of the precipitator action. l

Condenser 39A Vis .provided for the purpose of short circuiti` g toV ground stray currents that might cause radio or Video'inteEerenCe.' l l Section'l of the (precipitator is purposely made smaller in cross sectional area than section 2. This is donein order that'he'air or gas will not', in'gtlleral, immediately contact the inner `walls of section 2 and 4deposit foreign particles thereon but'instea'd will travel far enough to encounter the electrically charged liquid spray Vparticles emitted`intosection 2, thus preventing an undesirable deposit of debris at the input of section 2.

Metallic bell 39B supports and partially encloses insulator 111 through which the charging voltage is supplied to ne wires S. This arrangementprevents uthe insulator from being in the directip'ath of passingdebris and collecting the same whichwould impair the insulating properties of the insulator. Small holes 39C are provided in bell 39B for air to be drawn through from the action of fan 7 which will help keep the insulator clean.

Some of the wet steam emitted into `section 2 will condense therein. This liquid is drained away through an arrangement provided to prevent flashover to ground which consists of items 41A, 42A, and 43A as described above for the Figure 2 precipitator arrangement.

.Certain general statementscan be advantageously made at this point concerning the three illustrative embodiments of the presentirivention,which have just been specifically described.v These statements are set forth immediately hereinafter. l

It should .be noted .that .the walls of the various precipitator sections are fabricated from insulating'material ,o r provided of aV metal that is electrically biased above ground potential in order' to prevent or minimize lthe effect of the electrically charged foreign particles and liquid spray particles migrating to grounded surfaces with a consequent loss of charge `and a` defeat in the purpose of the precipitator action. Also, to preclude against the waste of power supplied to the precipitator.

Each precipitator arrangement` illustrated in this memorandum is shown grounded at several points. In actual practice it is usually best to make all such grounds to a common bus that is adequately grounded at one point. This method of grounding helps to preclude against radio and video interferences.

All high voltage leads on the exterior Aof a precipitator would of course be .properly ,insulated or shielded in actual practice. Suppressors for radio and video .interferenccs would be connected in such leads as required.

The several precipitator arrangements illustrated lhy Figures l, 2 and 3 and the Vassociated sectional views, are intended `to depict possible variations ,in the precipitator system as a whole.v The various indiyidual features indicated `in the drawings do `not necessarily apply only t the figure in .which they are elmun- For ,instance the Spray liquid heating .arrangement shown in Figure l can just as well be applied to the precipitator arrangement shown in Figure 2.

The'prefssure tank 31 indicated in Figure 2 could be suitablyapplied to Vthe precipitator arrangement shown in Figurel assuming spray heads l13I and supply 1 4 are properly' spaced and insulated from grounded parts of the system The section of the precipitator containing the spray heads and liquid spray electrical charging elements might just as well be placed at either the top or bottom of the precipitator 'for any particular arrangement indicated herein. l

l Although all precipitator arrangements shown in this memorandum indicate the input and mixing sections in a horizontal position they are not limited to the horizontal. They'could he suitably operated in the vertical or other positions. The output or condensing section 4 can also suitable operated in positions other than the horizontal.

The electrical charging arrangements for the liquid spray shown in Figures l, 2, and 3 can be applied interchangeably to any of `these precipitator arrangements including the vibrating or rapping of electrodes that is indicated st ectirnal view lA--IA of Figure l.

The Water Suray System shown in Output Section 4., 0f Figure 3A, could also rbe applied to the precipitator arrangements shown in Figure 1 and 2 in order to facilitate the condensing process.

Any of `the precipitator arrangements-illustrated herein could just as well have a mirri/ng section 2 of insulating material as shown in Figures l and 2 or have said section of a metallic material with an electrical biasing arrangement similar or equal to that shown in Figure 3.

Edged blades could be used in place of the fine wire in either the foreign particles and/or liquid spray electrical charging section for any precipitator arrangement illustrated in this memorandum The bell type insulator support 349A indicated in Figure 3 might be applied with advantage at any location in any ppecipitator arrangement where an insulator would be in the p ath of dirt, vapors, or anything that might unclesirably affect the insulator.

lArtis of the main sections of the precipitator system 1, u2, 3, and 4 need not necessarily be parallel or along the same line as shown in Figures 1, 2, and 3.

0.9 Ptattical and economical means for insulating theY non-discharging electrode means (in the specific example illustrated in Fig. l, as indicated at 18), is to centrally locate the non-discharging electrode in a hollow cylinder febriated frein electrically nOn-cQnductit/e material. The space between the electrode and the inner part of the hQIlQW Cylinder may be filled with a fluid having high electrical insulating qualities and high dielectric Constant, with said fluid being sealed within this space by an insutlating seal at each end of the cylinder near the ends of the electrode, .or various equivalent structures may be employed.

Numerous modications and variations of the present invention will occur to those skilled in the art after a careful study hereof. All such, properly within the basic spirit and scope of the present invention are intended to be included'a'nd comprehended herein as fully as if speciiically described, illustrated and claimed herein.

Tlieexact compositions, configurations, constructions, relativeposfitionings, and cooperative relationships of the variots component parts of the present invention are not critical, and can be`modiiid substantiallymwithin the spirit of pthe present invention. l

The embodiments of rthep'resent invention specifically described illustrated herein are exemplary only, and are not intended 'tQ limit ,the Scope 0f the present interltion, which is to be interpreted in the light of the prior art the appended claims only, withV due considera- Vtion for the doctrine of equivalents.

l claim:`

1. An electrical precipitator apparatus. of the liquid spray type cooperable for removing particles of foreign material from gas and requiring only limited charging potentials, comprising: gas duct means cooperable to transmit gas therethrough and including an input portion, an intermediate mixing portion having insulatingly separated inner and outer walls, and an output portion; rst ionizing means cooperable with said input portion and the input gas carrying particles of foreign material and tlowing therethrough for ionizing said particles of foreign material in said input portion, said first ionizing means comprising discharging electrode means, non-discharging electrode means cooperably spaced with respect to said discharging electrode means to define gas-How space therebetween, and electric power supply means cooperable to apply unidirectional electric potential at a predetermined polarity and voltage between said discharging electrode means and said non-discharging electrode means and across said gas-ow space and the input gas owing therethrough; spray chamber means having insulatingly separated inner and outer walls laterally displaced from and connected to said intermediate mixing portion; spray input means positioned in said spray chamber means at a location substantially laterally displaced from and substantially completely out of the :line of ilow of gas through said intermediate mixing portion and comprising nozzle means cooperable for producing and disseminating a liquid spray in said intermediate mixing portion across the ow path of said gas carrying particles of foreign material which have been ionized by said rst ionizing means; second ionizing means cooperable with respect to said spray input means and liquid spray therefrom for ionizing particles of said liquid spray prior to dissemination thereof in said intermediate mixing portion, said second ionizing means comprising discharging electrode means, non-discharging electrode means cooperably spaced with respect to said discharging electrode means to dene spray-passage space therebetween, and electric power supply means cooperable -to apply unidirectional electric potential between said discharging electrode means and said non-discharging electrode means of said second ionizing means and across said spray-passage space and the particles of liquid spray moving therethrough, with the discharging electrode means at a predetermined potential and polarity opposite to the polarity of the discharging electrode means of the iirst ionizing means whereby the charged particles of spray precipitate oppositely charged particles of foreign material carried by said gas; said non-discharging electrode means of said second ionizing means being coated by insulating material, and said inner walls being eiectively provided with electrical isolation means, thereby contining the electrical conduction to the liquid spray particles to a region isolated from ground by said inner walls and by the insulating material on said non-discharging electrode means; the outer walls of said intermediate mixing portion and said spray chamber means comprising an electrically conductive shield insulatingly spaced from and substantially encompassing said inner walls and being grounded; condenser-precipitator means cooperable with said output portion for separating particles of liquid spray carrying particles of foreign material from the mingled spray and gas stream; and discharge means for removing such separated liquid from said output portion.

2. Apparatus of the character defined in claim l, including a liquid transmissive and electric current nonl0 transmissive means effectively connected to said gas duct means to allow egress of condensed liquid therefrom while electrically isolating and insulating said gas duct means above ground.

3. Apparatus of the character dened in claim 1, wherein said electrical isolating means of said inner walls includes electrical biasing means effectively connected to at least inner wall of said intermediate mixing portion for biasing same to an electrical polarity similar to the polarity of the discharging electrode means of said second ionizing means.

4. Apparatus of the character defined in claim l, wherein said non-discharging electrode means of said iirst ionizing means, being coated with electrical insulation, is eifectively insulated with respect to said discharging electrode means thereof; and wherein spray nozzle means is provided for cleaning electrodes of said first ionizing means; and including a liquid transmissive and electric current non-transmissive means effectively connected to the spray nozzle means of precipitator to supply liquid under pressure to said nozzle means while electrically isolating and insulating said nozzle means above ground.

5. Apparatus of the character dened in claim l, wherein said input portion and said output portion are each spacedly perorately insulated from said intermediate mixing portion and wherein at least input portion is of smaller eiective cross-sectional area than said intermediate mixing portion; and wherein said condenserprecipitator means includes second spray input means comprising nozzle means cooperable for producing and disseminating liquid spray in said output portion across the llow path of the mingled stream of gas and liquid spray carrying particles of foreign material to aid in removing same from said mingled stream.

6. Apparatus of the character dened in claim l, including electrode cleaning means cooperable with at least certain of said non-discharging electrode means for cleaning same.

7. Apparatus of the character deiined in claim 1, including insulator means passing through wall means of said gas duct means and carrying electric leads connected to said electrode means, said insulator means being encompassed by and positioned in recessed chamber means located substantially out of the line of ow of gas through said gas duct means from the input portion to the output portion thereof and being provided with ingress holes whereby clean air will be drawn through said recessed chamber means minimizing the deposition of foreign particles from the main gas stream upon said insulator means.

8. Apparatus of the character dened in claim 1, wherein said spray chamber means is apertured at a location more remote from said intermediate mixing portion than the `location of the nozzle means in the spray chamber means.

9. Apparatus of the character defined in claim 1, including heating means cooperable with liquid supplied to said nozzle means of said spray input means.

l0. Apparatus of the character deined in claim 1, wherein at least certain of said non-discharging electrode means are effectively coated on the exterior surface with a material having low aiinity characteristics.

References Cited in the le of this patent UNITED STATES PATENTS

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