US2188695A - Electric precipitator - Google Patents

Description

.im 3o, 1940.

H. A. WINTERMUTE ELECTRIC PRECIPITATOR Filed Dec. 22, 1937 5 Sheets-Sheet 2 jm 30 1940 H. A. WINTERMUTE 2,188,695

ELECTRI C PRECIPITATOR Filed Deo. 22, 1937 5 Sheets-Sheet 5 Jan, 30,l 1940.

H. A. WINTERMUTE ELECTRIC PRECIPITATOR 5 Sheets-Sheet 4 'Filed Deo. 22, 1937 Jam 3G i94a H. A. WINTERMUTE 2,188,695

` ELECTRIC PRECIPITATOR Filed Deo.12l2, 1957 5 Sheets-Sheet 5 @WWA/136.

Dit

Patented Jan. 30, 1940 PATENT OFFICE ELECTRIC PRECIPITATOR Harry A. Wintermute, Plainfield, N. J., assigner to Research Corporation, New York, N. Y., a corporation oi New York Application December 22, 1937, Serial No. 181,239

24 Claims.

l The invention relatesto a method and apparatus for electrically treating iluilds and particularly to the removalof suspended particles from iluids comprising the use of apparatus including a. discharge electrode system and a plurality of nondischarge electrode systems which are separately or differently connected to or influenced by means providing electrical energization..

Typically the apparatus of the invention comprises essentially a discharge electrode system and two non-discharge electrode systems. One oi the non-discharge electrode systems is positioned andenergized toact as a collecting electrode and the other non-discharge electrode systern acts as an auxiliary or intermediate electrode, or the two non-discharge electrode systems alternately function as collecting and auxiliary electrodes. The two non-discharge electrode systems are so mounted and connected electrically that the electric fields between each of these systems and the discharge electrode system are different at any given instant. They may be so connected to a source oi current through suitable energy-directing devices that an electric potentialis connectedv between the discharge electrode system and each of the nondischarge electrode systems alternately. In the intervals between positive energization the nondischarge electrodes may be (ie-energized by proper connections, or they may be allowed to oat in the eld terminating on the other electrode, by so arranging the connections in these intervals that the electrode system which is to iioat is substantially insulated from the other electrode systems. If one of the non-discharge electrode systems always functions as the principal collecting electrode, it may be arranged continuously to float in the elci terminating in the auxiliary electrode system by substantially insulating it from the discharge and the auxiliary electrode system so that the field to the collecting electrode system is at all times an induced" field.

A principal object of the invention is to provide improved means for electrically removing suspended particles from uids vcomprising discharge electrodes and a novel arrangement of non-discharging electrodes with energizing means therefor whereby an efficient removal of the particles withapparatus of small size is ob- (Cl. IBB- 7) velocity exists adjacent said electrodes which provides conditions favorable for precipitation of the suspended particles.

An object of the invention is to use a plurality of electric fields to charge suspended particles 5f' in a fluid stream. and cause the particles to migrate into a zone where the uid is moving at low velocity and across which an electric field is maintained a sufficient proportion of the time to insure eiiicient precipitation of the particles. 1"

Another object of the invention is to electrically remove suspended particles from a fluid stream and collect them adjacent electrode surfaces where they are agglomerated and precipitated by novel and efilcient means comprising ufboth electrical and mechanical forces.

The means by which the above-mentioned and other objects of the invention are realized will now be described with the aid of the drawings in which:

Fig. l is a plan View of a section, taken at I-I of Fig. 2, showing a preferred embodiment of apparatus constructed in accordance with the invention; l

Fig. 2 is a side elevational view, in section; 25 taken at 2--2 in `ilig. 1, of the preferred apparatus;

Fig. 3 is a cross-sectional view of the preferred apparatus taken at -S in Fig., i;

Fig. iis a diagrammatic representation of an 30 arrangement of switching and rectii'ying apparatus suitable for the energization oi the apparatus shown in Figs. 1 to 3;.

Fig. 5 is a diagrammatic representation in partial sectional elevation ci another embodiment of 3f the invention;

Fig. 6 is a fragmentary section on line -l-S of Fig. 5;

Figs. '7, 8 and 9 illustrate alternative schemes, within the scope of invention for arranging the 40 electrical connections between the electrode and iii the current source, and

Fig. l@ is a sectional elevation of an embodiment of the invention particularly adapted for the electrical treatment oi' liquids.

Apparatus comprising a preferred embodiment of the invention will be described as applied to the removal of suspended solid particles from gases. Many of the forces acting, conditions set up, and results obtained will be realized when 59 apparatus constructed in general accordance with the following description is applied to the treatment of liquids.

Referring to Figs. l, 2 and 3, numeral l identifles a casing or chamber in which the electrodes 55 members d which are in-turn dependent from casing I and to which they are electrically connected, comprise what are commonly knownas collecting electrodes and provide the surfaces upon which much of the suspended matter is electrically precipitated. The inside lateral surfaces of casing i also serve as collecting surfaces. Spaced from plates 5 are auxiliary electrodes 6. These electrodes commonly, as here shown, com prise vertically extending rods E', spaced horizontally from one another and from plates 5 and are supported by horizontally extending members 1 which are in turn supported by members 8 resting on insulating means 9 Ainfsl'ieltering boxes II). Discharge electrode. assembly I3 is made up of the actual discharge elements I3', from which corona discharges. emanate when energized to a suitable potential, and supporting members. It comprises attenuated members' I3.

commonly wires, depending from members l, supported in turn through members le, I6 and il by insulators ld, only one of which is indicated, inboxes it on top of casing I. Orifice rings 2E permit high potential members i6 to pass through the bottom oi boxes l@ without discharging thereto. Members lbf are held taut by weights 2l. In an illustrative 'apparatus which has been operated with very satisfactory results, plates 5 were spaced l2 inches apart with discharge elements i3', made of 1/8 inch diameter {or twisted 1/8 square) rods, placed midway between the plates upon '7% inch centers. Reds B' were 1/2 inch in diameter and spaced 11/2 inches apart, center to center. Rods were positioned with their centers 1% inches `from the surface of plate e. When plates 5 are of corrugated material the spacing from plate to plate may advantageously be 14 inches. Good-results have been obtained with elements i3 spaced as close together as 4 inches, center to center.

Across the bottom of electrodes '5 are aligning members` 22 and electrode elements t' are held in alignment by horizontally extending members 23 which are tied together at their ends by members 26. .The collecting electrodes 5 and 8 are shaken or rapped" by agitation of bar which is connected to the several bars 22 and projects outside casing l `so. that it `may be reciprocated manually or by power means, not shown. Upon reciprocation of bar 30, electrodes 5 are pulled out of their vertical position and strike upon members 23 and shake them, and, elements 6', being attached to members 23, are shaken also. The sides of casing l can be rapped from without to remove material deposited upon their inner surfaces but it is desirable to mount stops 3l and .32 on bar 30 making this bar serve to rap the sides of the casing while limiting the extreme movements of bar 30. The method ori-rapping just described makes rapping possible without disconnecting the current source. The rod curtain electrodes. E' are grounded when theyl contact electrodes 5 but this condition offers no electrical diiiicu-lty as will be pointed out when the method of electrode energization is described. In fact, occasionally grounding the electric charge on electrode 6 appears to bea contributing factor in the dislodging of the material from the' surfaces of this electrode.

Material shaken from the collecting electrodes is prevented from moving horizontally between the electrodes by transversely positioned baille means 34 which tend to prevent the gas being treated from moving along the collecting surfaces and carrying the detached material in suspension towards exit 3. Baffles 34 are supported by the same structures which support electrode elements 6 and are maintained at the same potential -as elements 6. Grounded plates 5 are positioned far enough away from bailles 34 to prevent sparking between these members.

Q Casing I and electrodes 5 are commonly maintained at lground potential, the connection to ground being indicated at 2l. Auxiliary electrodes 5 are connected to a source of energy to be described later by a conductor 25' passing through bushing 25 in one of the insulators S. Discharge electrodes I3 are energized through conductor 2B in insulating bushing 26 passing through the top of one of the insulator boxes I9.

Fig. 4. illustrates diagrammatically a preferred method of energizing a precipitator constructed in accordance with the invention, inparticular,

the precipitator shown in Figures l, 2 and 3. AA

transformer el draws current from a single phase source ed, a balla-sting reactance 42 being utilized in the low voltage circuit for controlling the voltage and as a ballasting load. Arectier 43 of the mechanical type revclvingin synohronism with the alternations of current pw in source LIB recties the current fromthe highy voltage winding of transformer il and` makes all half waves available through conductor 23 at one polarity, usually negative polarity being preferred for the energization of discharge electrodes i3. All the half waves of the rectied current ilcw through conductor @5 to synchronous selector IW which permits every other half wave to iiow through resistance or other voltage control B1 and conductor slit to electrode 8 and alternate half waves through voltage control 48 and conductorv 46 to grounded electrode 5. The three groups of electrodes are insulated from one another so it will be seen that at every other half wave, with the revolving switches as shown, a circuit exists which includes lead 4S, electrode-5, lead 28', electrode i3', and the gaseous medium between electrodes' and i3. At alternate half waves, when the switches have turned 90' mechanical degrees, corresponding, assuming a four pole motor revolving at i800 R.. P. M., to 180 electrical degrees of a 60 cycle current source, an alternate circuit is com pleted which includes conductor 25', electrode B, lead 23', electrode I3, andthe gaseous path between electrodes 6' and I3. 4At half cycles when conductor 25' is not connected to the current source (as shown in the ligure) ,electrode 6 iloats, electrically, with a potential whichreachesavalue depending upon the residual potential it retains from the previous half cycle and the number of charged particles and ions resulting from the discharge from electrode I3 which deliver electric charges to it.

The apparatus shown in Figs. 1, 2 and- 3 'and energized with the circuits outlined in Fig. 4 is l of particular value inremoving supended solid particles fromv gases. chamber I are, to a considerable degree, ionized by the strong electric fields existing alternately` Gases passing through between electrodes I3 and 5 and between elecl The gaseous ions become atfv tors, in particular, the conductivity of the parconducting particles when suspended in a dry gas,

v which enables them to retain their non-conductlgood conductors but which do not agglomerato are dicult to collect because they jump back and forth between electrodes like the pith ball in the common laboratory experiment, lt is to the overcoming of such diiliculties that the present invention is especially directed.

In the invention a quiescent zone is established, bothlas regards gas flow and electrical conditions, between collecting electrodes 5 and t which' facilitate the collection, agglomeration, and precipitation of suspended particles. During the half cycle when the electric field exists between electrodes il? and t many of the ionized particles are riven between rods 6 and precipitated upon the surfaces of electrodes 5. During much of this period ions are continually forced toward the collecting surfaces and upon the deposited particles and hold the particles to the surfaces. Some oi the ions and ionized suspended particles are deposited at least momentarily, upon rods ii' because these rods are at lower potential than discharge elements i3. During the succeeding half cycle, with the electric elds'extending from electrode i3 terminating upon electrode S, a considerable portion of the suspended particles may vbe deposited on the rods. Some of the particles'however, due to their momentum, to the extension of parts of the field to electrode 5, and to local gas movements, pass between the rods. During this half cycle, when the elec trodes d are not being bombarded with a surplus of ions originating adjacent the discharge fili electrodes lo the collected material on the surfaces of electrodes has an opportunity to give up to electrode 5 the charges which cause it to be attracted to the electrode and falls immediately by gravity into a hopper provided for the purpose below the electrodes; or, it may flutter back and forth between the plate and rod electrodes as it moves downwards towards the hopper. With forces alternately applied.v as described, the spaces between the rods remain open and a minimum of material .stays upon the rods.

A complete theoretical explanation of what happens in apparatus such as that just described is not available and will not be attempted, but the results obtained are unique and make for increasedI efficiency in gas cleaningr with electrical fields. `The shifting of one terminal of the electric 'lield between an intermediate perforate electrode system, as illustrated by the rod curtain construction 6, and another :system here illustrated by plates 5, makes for localized movements of the collected material as it moves downwards. The contrast between the operation of an electric precipitator without the auxiliary periorate electrodes and apparatus comprising auxiliary electrodes in accordance with the present invention is striking. In the usual precipitator. when deposited material of refractory electrical characteristics loses its charge. and drops away from a collecting electrode or is repelled because it retains or takes up charges oi` opposite sign, it wanders back into the gas stream to be recharged and reprecipitated, if effective corona discharge is present, and asthis is repeated many of the agglom-erates and larger particles move along the electrode surfaces towards the exit. The requirement that this dislodged material be reionized before it is redeposited often overburdens the capacity of the apparatus, and, as moves out into regions oi high gas velocity, it may ce carried along to the exit before being reprecipitated. or it may move about and build up peculiar formations on the electrode surface which are conducive to back corona.

With the apparatus described herein, materialy breaking away from the collecting surfaces keeps within the space between the auxiliary collecting electrodes ii and the electrodes ii and either .reprecipitates or drops into the hopper with or without periods of reprecipitation. The fact that the gas velocity is low in the spaces between the electrodes, especially when baffles are positioned across the spaces as indicated by members makes for a more denite settling oi the material. Another condition favorable for precipitation is the electric eldoi changing characteristics that extends across this space. Rod curtain or screen type electrodes have previously been placed in front of impervious collectingelectrodes either at the same potential (e. g. ground) or at such poinsulating means and independent oi energizing agencies. The results have not been as expected.

.tential as 'they can assume when suspended by Sil) With the electrodes at a common potential a araday cage condition exists making it impossible to drive more than minor portions of the charged particles between the rods unless they are spaced far apart. Instead.' the material collects upon and bridges across the rods. And with insulated rods the potential is never brought to .a` denite value with regard to the discharge electrodes,

but builds up to values approaching those on' the discharge electrodes resulting in arcing be-z tween the rods and the usually grounded plate electrodes.

As mentioned beto-re, While the electrical conditions provided by the invention are favorable for the dislodgernent and settling of material which has been deposited and agglomerated on 'the collecting electrodes it has been found advisable to provide mechanically or manually operated rapping means. is the mechanical forces are applied to' the plate members between the. rods, there is no evident disturbance oi' the electrical conditions during rapping periods. With plates 1" hanging in their usual vertical position, electrodes t probably retain sucient Y charge so that they never reach ground potential. But, when plates 5 and rod electrodes are rapped together to dislodge deposited material. electrodes t are frequently grounded. As the half waves that energize the system through conductor dit are permitted to build up to higher'potential above ground than are alternate half waves conducted throughy conductor 25', because the distance between electrodes i3 and i5 is greater than between electrodes i3 and in', it is advantageous if not ,necessary to lower the voltage in this circuit at tirncs of rapping. When rapping is taking place electrode t is brought to ground potential and. as the distance between electrodes i3 and is not great enough to sustain the voltage set up in the circuit including conductor tt,

`this voltage is reduced during rapping to approximately the voltage in the .parallel circuit including conductor 25' by increasing resistance 68 or by other means known `to the art.

bottom to form which are commonly supported by the grounded structural frame (not shown) to which casing 6| is attached. Other rods 63 yextend parallel to each other and to rods 62. Rods 63 depend from horizontally extending supports 13 and these aresupported by insulating means (not shown) which permits them to be energized at suitable potentials. A row of discharge elements 64, for instance, small rods or wires, is

suspended vertically between the parallel rows l 'of rods 62 and a row of similar discharge electrode elements 64a `is suspended between the parallel rows of rods 63. Discharge elements 64, 64a are supported by horizontal supports 15 which are in turn supported by insulators in the manner known to the art although not indicated in the figures. It will be noted that in this embodiment of the invention, adjacent pairs of rods 62 and adjacent pairs of rods 63 are brought together, respectively, at top and closed links and that these links hanging in spaced relationship alongA members 12 and 13 respectively, form passages with perforate walls for the gas being treated. It is also to be noted that discharge elements 64, 64a

positioned in the passages or treating cells, ex-

tend above members 15 as indicated by extensions 64 vand below steadying members 16 as indicated by extensions 64 so that the electric fields and resulting corona discharge will extend, 'into these end regions of the cells.

' Rods 62 and 63 may be shaken to loosen de posited material which may cling tenaciously to them by the mechanism indicated, comprising motion.

possibility of sparkover from one a horizontally extending anvil extension 69, at-

tachecl to the several pairs of rods or links making up a collecting electrode assembly and a rapping rod 61 upon which are hammer members 68 that loosely guide anvil 69 and strike against it when rod 61' is given a reciprocating A single bar' 61 can, by the proper location of sets of hammer members 68, strike all the anvils connected to electrode links of common potential. Another bar 61', spaced sufliciently distant from bar 61 to eliminate the bar to the other, can be made to jar the anvils on the alternate rows of links. While bars 61 and 61 are shown in Fig. 6 at different levels for the sake of clearness, they would ordinarily'be provided at the same levels.

The electrodes in the arrangement shown in Figs. 5 and 6 are energized from a single phase source, the current being rectified and .distribn uted by mechanical switches 80,'8I in the manner illustrated in Fig. 4. Discharge electrodes 64, 64a are maintained at a high potential abovev ground and at constant polarity by means of conductor 04 which is alternately connectedl to first one high voltage terminal and then the other'high voltageterminal of transformer 13. Rods 62, preferably connected to ground, are connected every other half cycle by conductors 82 and 18 to the end of transformer 10 tlien opposite to the terminal connected to conductor 64. A t alternate half cycles rods 63 are connected byconductors 03 and 11 to transformer 19. The voltages 'impressed between the electrodes and the electric fields set up can'be easily comprehended by noting dotted lines 58 and 59.

When the transformer voltage is impressed acrossthe gas between electrodes 64, 64a and electrodes 62 (the solid line connections at the rectiilers indicate this condition) the electric fields extend from the discharge electrode 64 to collecting electrode rods 62 as indicated bylines 59h and from electrodes 64a to rods 62 as indicated by lines 69a. lftods 63 are electrically "floating .during this-half cycle and assume a' potential intermediate thepotential o discharge electrodes 64a and ground potential. The electric fields pass through and between rods 63 and terminate upon rods 62 during this half cycle and the gas and solid particles in the precipitating space between rods 62 and 63 are subjected to the forces of such fields during this period. During alternate half cycles of the energizing current when the transformer voltage is impressed across the gasI between electrodes 64, 64a and 63, electric fields are established between electrodes 64a and 63 as indicated by lines 58h and possibly between electrodes 64 and rods 63 as indicated by lines 58a. This latter relationship cannot be given with certainty because it depends upon'the capaci tance of the transformer windings and other conductors to ground, insulator leakage, and other factors but it can be stated that during these half cycles diiferent conditions of field and ion bombardment in the precipitating space between electrodes 62 andL 63 do exist from the than is obtained with electric precipitators as commonly constructed and energized.

Fig. 7 diagrammatically illustrates an arrangement of electrical apparatus which will simultaneously but independentlyenergize two separate groups of electrodes such as those shown in Figs. 1, 2 and 3. Transformers 89 and 00 both receive current at comparatively low voltages from single phase source 88 and step the voltage up to values required by the gas treater. The current supplied through transformers B9 is rectied by rotary switch S3 and caused to flow through conductorf |03 and 99 across the gas between ,discharge electrode |00 and grounded plate electrode |02.v Rectifier 04 is used to rectify the current from transformer 90 and this current flows through conductor |04, common conductor 99, and the gas between electrode |00 and auxiliary collecting electrode |0|, e. g. of rod curtain construction. Wlth the connections shown, full wave current at constantpolarity flows through.

both systems of electrodes simultaneously. That the voltages may be of suitable values and the current may beproperly divided, resistances or otherv voltage control and current ballasting means are utilized. Low voltage resistance 0|v and high voltage resistance 96 and 01 are in circuit comprising transformer 89 1 lll point. In other words, for example, electrode |25,

source by conductor |04 but some current carrled by the ionized gas and charged particles passes through electrode IBI, reaches electrode M2, and returns through conductor it. The voltage distribution is arrived at' by trial. For instance, a voltage drop from electrode lili to electrode m2 should provide a strong enough rleld to cause precipitation of charged particles on electrode |62 but should not be strong enough to cause disruptive breakdown of the gases be tween these electrodes.

Fig. 8 shows a schematic hooi: up using a two phase circuit |05 for energization. With this arrangement increments of both half waves are used to energize both circuits but because of the phase relationship of the two phases the increments or peaks of the voltage waves are impressed alternately between discharge electrode llt and electrode lll and between electrode Ilii and electrode l 2. This is accomplished by using very short stationary shoes H5, llt on rectiers Hi8 and ltd, respectively. If shoe llt is very short it permits only the peaks of the currentwaves from phase |0511 to flow through the circuit of which it is a part, including transformer tilt, and this current flow is terminated or nearly terminated before shoe lili 'makes contact with the revolving connectors of rectifier lll@ and permits current to flow from phase W51) through transformer lill. By using short shoes and setting rectifier |09 radially 45 mechanical degrees from rectier |03 so that advantage is taken oi the 90 electrical degree displacement of the phases, a sequence of energizatlon is set up which comprises an electrical impulse from phase Ita to energize the circuit which includes the gap between electrode |||l and electrode |52 immediately followed by an impulse from phase web to energize the circuit including the gap between electrodes illl and Iii. This sequence is repeated, all voltage peaks from one phase losing rectified and impressed at constant polarity across one set of electrodes and all voltage peaks from the other phase being impressed at constant polarity across the other set of electrodes but 90 electrical degrees later. This system, with a single high tension connection H3 to electrodes llt, causes a very long peak voltage condition to exist adjacent discharge electrode lit although grounded collecting electrode surface M2 is used as a terminal for such condition only hall the time or the usual time for single phase peak wave energization. The conditions emsting between electrode and electrode ill. Vare iavorable for precipitation and deposition of the material in the hoppers below the electrodes.

Fig. 9 illustrates, schematically, how one single phase transformer with a mid-point terminal |2I can housed with two rectiflers |22, |23 to distribute energizing impulses in accordance with the invention. This arrangement leaves discharge electrode |24 continuously connected to the mid-point |2| of the high tension winding of transformer |20 and alternately connects one half the winding across the gap between discharge electrode |24 and auxiliary collecting electrode |25 and the other half of the winding across the gap between discharge electrode |24 and grounded electrode |26. By utilizing one half the transformer winding duringone halt (say, the negative half) of the current `wave and the other half of the transformer winding during theother half of the current wave, the ends of the winding will always, when connected, be at the saine polarity with relation to. the midand electrode |25, can always be maintained positive with regard to electrode |24.

In all the iigures mechanical switching devices have been shown as rectifying means. Other devices such as hot cathode tubes can be used as rectiflers in some instances, examples of such use`being shown in my Patents Nos. 2,000,654 and 2,069,692.

Fig. lll shows apparatus particularly suited to the treatment of liquids. It 'comprises a circular shell |39 open at the top (although the top can be closed for outdoor use or in treatments ini volving explosive components) and closed at the bottom. The liquid to loe treated, for example, petroleum oil contaminated with a small amount of water in dispersed form, enters through inlet itl and leaves through outlet i32. The outlet encircles the shell near the top as an annular passage |32 and slots |33 in the wall of the shell permit the oil to pass into the culet. The liquid during 'treatment is prevented from moving along the side of shell i3|l at any appreciable velocity by baille means |43.

Discharge or concentrated iield electrode itil is suspended axially in the shell from supporting structure |35 which is supported on insulators |35. Auxiliary or intermediate electrode i3? is positioned concentrically within the shell and comprises 'torus rings,`preferably oi metal tubing, vertically spaced and supported by metal struts |39. The composite electrode or cage i3? is supported on a horizontal open frame it@ and this frame is supported in desired position by insulators Ml in remote boxes |43. Electrode i3d is energized through conductor |26' and electrode |37 is energized through conductor |25' passing through an insulator ldl. Conductors |25 and l 25' are connected to a source of energy suc'h as that shown in Fig. Al and shell i3d is grounded.

The electrical and hydraulic conditions present in the apparatus, in the region between electrode G3i' and shell |39 in particular, are Favorable for the. agglomeration and collection oi the water particles. The Water collects in masses large enough to overcome surface tension and other buoyant forces and settles to the bottom o the apparatus to be drawn oiT through pipe l Il.

The term non-discharge electrode, as used herein, is intended to denote an electrode of such configuration as to substantially prevent or minimize corona discharge therefrom at elevated potentials below the ,potential at which disruptive discharge occurs.

I claim:

1. Apparatus for electrically treating a fluid comprising a discharge electrode, two non-,discharge electrodes insulated from the discharge electrode and from each other and means for alternately establishing an electric eld between the discharge electrode and each of said non'- discharge electrodes.

, 2. Apparatus for electrically treating a fluid comprising a discharge electrode, two non-dis-v charge electrodes insulated from the discharge electrode and from each other and means for establishing an electric leld between the discharge electrode and each of said non-discharge electrodes, including means for independently varying the strength of the electric fleld'hetween the discharge electrode and at least one of said non-discharge electrodes.y

3. Apparatus roi' electrically treating a iluid comprising a discharge electrode, two non-discharge electrodes insulated from the discharge electrode and from each other, and energydirecting means for establishing independent unidirectional electric fields of the same polarity between said discharge electrode and each of said non-discharge electrodes.

4. Apparatus for electrically treating a fluid comprising a`discharge electrode, two non-discharge electrodes insulated from the' discharge electrode and from each other, energy-directing means for establishing unidirectional electric fields of the same polarity between said discharge electrode and each of said non-discharge electrodes and means for independently Varying the strength of at least one of said fields.

5. Apparatus for electrically treating a fluid stream comprising a discharge electrode, a collecting electrode spaced from the discharge electrode, a non-discharge electrode positioned between the discharge electrode and the collecting electrode, and energy-directing means for estab-- lishing independent intermittent electric fields of the same polarity between the discharge electrode and the other two electrodes.

6. Apparatus for electrically treating ya vfluid stream comprising a discharge electrode, a coll lecting electrode spaced from the discharge electrode, a non-discharge electrode positioned between the discharge electrode and the collecting electrode, and energy-directingmeans establishing independent discharges between the discharge electrode and the other two electrodes.

7. Apparatus for electrically treating a fluid stream comprising a discharge electrode, a collecting electrode spaced from the discharge electrode, a non-discharge electrode positioned between the discharge electrode and the collecting electrode, and energy-directing meansestabiishing dual electric fields from the discharge electrode, one of the said elds terminating on the collecting electrode and the other on the nondischarge electrode.

8. Apparatus for electrically treating a fluid comprising a discharge electrode, a collecting electrode insulated from the discharge electrode, a non-discharge electrode positioned between the discharge electrode and the collecting electrode and insulated from both the other electrodes, and energy-directing means whereby an electrical field is established between the discharge electrode and the non-discharge electrode.

9. Apparatus for electrically treating a iiuid comprising a discharge electrode,l a collecting electrode insulated from the discharge electrode. a non-discharge electrode positioned between the discharge electrode and the collecting electrode and insulated from both the other electrodes, and energy-directing means whereby an electrical field is intermittently established between the discharge electrode and the non-discharge electrode.

10. Apparatus for electrically treating a uld comprising a discharge electrode, a collecting electrode insulated from the discharge electrode, a non-discharge electrode positioned between the discharge electrode and the collecting electrode and insulated from both the other electrodes, and energy-directing means whereby an electrical Held is established between. the discharge electrode and the collecting electrode.

11. Apparatus for electrically treating a fluid comprising a discharge electrode, a collectingelectrode insulated from the discharge electrode,

a non-discharge electrode positioned between the -discharge electrode and the collecting electrode and insulated from both the other electrodes, and

energy-directing means whereby an electrical.

iield is. intermittently established between the discharge electrode and the collecting electrode.

12. Apparatus -for electrically treating a uid stream comprising a discharge electrode, a col.- lecting electrode spaced from the discharge electrode, anon-discharge electrode positioned between the discharge electrode and the collecting;

electrode, means for establishing independent intermittent electric fields of the same polarity between the discharge electrode and the other two electrodes and bafiie means positioned `to at least partially shield the space between the non-discharge and the collecting electrodes from the flow of the fluid stream.

13. Apparatus for electrically treating a uid stream comprising a discharge electrode, a collecting electrode spaced from the'discharge electrode, a non-discharge electrode positioned between the discharge electrode and the collecting electrode and closer to the collecting electrode than to the discharge electrode. and means for establishing independent intermittent electric iields of the samepolarity between the discharge electrode and the other two electrodes. 4

14. Apparatus ior electrically treating a fluid stream comprising a discharge electrode structure extending in the direction oi' iiow of the stream, a collecting electrode structure spaced from and parallel to said ldischarge electrode structure' an additional non-discharge electrode structure positioned between said discharge electrode structure" and said collecting electrode structure, baille means positioned in the space between .the collecting electrode structure and the non-discharge electrode structure, and means for establishing independent intermittent electric elds of the same polarity between the discharge electrode structure and the other two electrode structures. I

l5. Apparatus for electrically energizing a treater having a discharge electrode system and two non-discharge electrode systems comprising a high voltage transformer having its low voltage winding connected to a source of alternating current, means connecting the mid-point of the secondary winding of the transformer to the discharge electrode system and means connecting each of the terminals of the secondary with one of said non-discharge electrode systems including energy-directing devices adapted electrically to connect eachv of said non-discharge systems with the corresponding terminal only at alternate and opposite half-cycles of alternation.

16. Apparatus for electrically energizing a tr later having a discharge electrode system and two non-discharge electrode systems comprising a pair of high voltage transformers having their low voltage windings connected to the same source of .alternating current, means connecting said electrode systems with the secondary Windings o f said transformers including energy-directing devices adapted to connect said discharge electrode system to each of said secondary windings at terminalsof the same=polarity in synchronism with the alternations in current and to connect each of said non-discharge electrode systems in alternation to the opposite ends oi.' one of said secondary windings. g

17. A method of treating fluids which comprises passing a fluid in a stream adjacent a zone of relative quiescence. establishing a high potential ileld across said stream and causing said eld to terminate in alternation on electrode surfaces on each side of said zone of relative quiescence.

18. A method of treating iiuids which comprises passing a fluid in a stream adjacent a zone of relative quiescence, establishing a high potential iield across said stream, causing said eld to terminate in alternation on electrode surfaces on each side of said zone of relative quiescence and varying the potential of said eld with each alternation.

19. A method of treating iiuids which comprises passing a stream of fluid along a discharge electrode system and adjacent a quiet zone deiined by two non-discharge electrode systems and subjecting said fluid alternately to a high p0- tential electric i'ield terminating on one of said non-discharge electrodes to charge particles in the iiuid stream and initiate movement of the discharge electrodes, a. plurality of sets ofl permeable non-discharge electrodes spaced from said discharge electrode sets, circuit elements electrically connecting said sets of non-discharge electrodes in two groups, each consisting of alternating sets of non-discharge electrodes, with said discharge electrode sets whereby independent intermittent electric fields of the same polarity may be established between the sets of discharge electrodes and each of said groups of non-discharge electrode sets.

22. Apparatus for electrically treating a iluid stream comprising a plurality of sets of discharge electrodes extending transversely of said gas stream, a plurality of sets of permeable nondischarge electrodes spaced from said discharge electrode sets, circuit elements electrically connecting said sets of non-discharge electrodes in two groups, each consisting of alternating sets of non-discharge electrodes, with said discharge 'electrode sets whereby independent intermittent electric iields of the same polarity may be established between the sets of discharge electrodes and each of said groups of non-discharge electrode sets.

23. A method of removing suspended material from a fluid which comprises passing a stream of the fluid adjacent a quiescent zone, establishing an electric eld across said stream and intermittently extending said iield across said quiescent zone whereby suspended particles in the iiuid are transported into the quiescent zone and are therein lpermitted to settle by gravity into a removal zone displaced from the iiuid stream. A

24. A method of treating fluids which comprises passing a stream of fluid along a discharge electrode system and adjacent a quiet zone dened by two non-discharge electrode systems and subjecting said fluid to a high potential electrical neld terminating on one of said non-discharge electrode systems while maintaining `the other non-discharge electrode system substantially insulated from the rst non-discharge electrode system and from the discharge electrode system. I

HARRY A. WINTERMU'I'E.

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