ML19254C524

Ack Receipt of .Offers Solutions for Disposal of Contaminated Water:Electron Repulsion & Double Layering

ML19254C524
Person / Time
Site:	Crane
Issue date:	10/11/1979
From:	Yeh G VILLANOVA UNIV., VILLANOVA, PA
To:	Harold Denton Office of Nuclear Reactor Regulation
References
NUDOCS 7910160322
Download: ML19254C524 (18)

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October 11, 1979 Dr. Harold R. Denton, Director Office of Nuclear Reactor Regulation Nuclear Regulatory Commission Washington, DC 20555

Dear Dr. Denton:

Thank you for your letter of September 14, 1979.

I was glad to make the suggestion to help improve conditions at Three :lile Island Nuclear Station Unit 2.

If you have not found a practical solution to the disposal problem of the vast quantity of contaminated water at the above nuclear station, you might like to carefully consider the feasibility of the following new technologies as applied to the problem:

1)

Electron Repulsion (U. S. Patent No. 4,066,526)

This method may help concentrating the contaminated water, th-greatly reducing its volume to facilitate its disposal.

2)

Doubla-Layering (U. S. Patent No. 3,790,461)

-This method may help reducing the volume of the contaminated water to a minimum. To further facilitate the disposal of the highly concentrated liquid, the casing of the double-layering apparatus may be constructed of a good Garmn-shielding material or materials; and light materials good for neutron shielding such as carbon (graphite), aluminum dust (or fines),

minerals, etc. may be used as the adsorbent packed in the apparatus,thus lending whole apparatus to direct disposal when it is completely saturated with radioactive species and particles.

The f easibility of the above two technologies as applied to the separation or removal of radioactive species and/or particles in water is based on the f act that these radioactive masses are electrically charged as a result of ionization produced by radiation.

Please let me know if you need any further information relating to the,above two technologies.

Si cerely, D10160 I

868 338 W'

George C. Yeh Professor of Chemical Engineering

Feb. 5,1974 G.C.YEH 3,790,461 SEPARATION OF A LIQUID CONTAINING CHARGED PARTICLES OR/AND FOLARIZABLE MOLECULES Filed May 20, 1971 h

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300R D E C United States Patent Office 3 788>48' Patented Feb. 5,1974 1

2 3.790,441 tion method provided by the present invention, no cut.

SEPARADON OF A LIQUID COVI%fNC rent should be flowing through said liquid during the en-CHARGED FARUCLES OR/AND POLAR-tire operation: and the only power requirement other than IZABLE MOLECULES that needed for pumping the liquid would involve only George C. Yeh, wittistown Township, Chester County, 3 the very limited amount of electncal energy that is needed P

y Drive. R.D.1, Newtown Square, Pa.

to maintain the desired electrostatic charge (either rosi-tive or negative) on the surface of said particulate matter.

.FIIed May 20,1971. Ser. No.145,527 The rate and efficiency of separation by the present in-Est. CL Belk a/00 U 5,.CL 204-130 R vention are not proportional to the applied electrostatical 10 etatm 10 potential, as may be seen from the examples given below.

The above described characteristics of the separation AltTIltACT OF THE DISCLOSURE method provided by the present,invention are the e Whien a liquid containing charged particles, such as portant and unique features of this invention.

ions, electrolytes, free radicals and colloids or/and mo!c 13 Unlike all the known electrical separation me: bods, cules having pober or/and polarizable properties is the present invention involves no faradaic processes; and brought into contact with an electrostatically charged sur-therefore, neither gases nor other forms of products are face,. a double layer of said charged partic!cs or/and formed within the system during the separation oreration said molecules may be formed at said surface. Separation by the present invention. Furthermore, the difficul ties of said charged particles or/and said molecules from said go brought up by the solute build-up at the membrane front liquid can be accomplished if said liquid in the bulk is or by the great resistance to the current flowing through replaced from sakt electrostatically charged surface, after a dilute solution that are common to all the known elec-the coneing.

trical methods do not exist in the separation method pro-v ded by the present invention.

This invention relates to a method and apparatus for 25 The results of extensive experimental study have shown separating a liquki containing charged particles, such as that the rate and efficiency of separation by tae present ions, electrolytes, free radicals and colloids or/and mole-nSention are extremely high; and complete separation cules having polar or/and pelarizable properties by em-of liquids containing charged particles or/and polarizable ploying an applied electrostatical potential (either posi-molecules at any concentration is not only practicable but tive or negative) as the driving force for separation. It is 30 very simple and economical. According to the experi-particularly concerned with the method and apparatus for mental results obtained, the followine general trends seem separating said charged particles or/and said molecules to apply very well to the separation by the present inven-comprising the steps of bringing said liquid into intimate tion involving various aqueous and organic solutions of contact witzt a mohi, preferably a finely divided particu.

more than twenty.five different electrolytes and of twelve late matter, inducing the formation of a double layer of 33 polarizable molecules:

said charged particles or/and said molecules by an applied (1) The separation efficiency (ratio of the amount of electrostatic charge to said solid, and then replacing said solute removed to the total solute contained in the feed e

liquid;in the butt from said solid or vice sersa. Said soltation that had been passed before the breakthrough finely divided peruculate matter may preferably be point was reached) is higher when a lower electrostatical f

packed in a bed, permitting said liquid to Itow through 49 potential is applied.

the bed to facilitase intimate contacting with said liquid.

(2) To obtain the same fractional separation, a higher After having saturated with said

• charged particles or/

electrostatical potential is required when a lower feed and said molecules, said bed may be regenerated by turn-concentration is used.

ing off said applied electrostatic charge and then letting 45 (3) The complete separation can be obtained regard-less of the feed concentration if enough amount of par-said charged particdes or/and said molecules that are held within sand double layer or layers be drained with said ticulate matter is used in a continuous contacting opera-liquid from said bed. No disposal problem of a secondary tion.

stream exists in the separation method provided by the (4) ne electrostatical potential range that normally brings the desirable separation results is in between sev-present invention.

Electrical energy has been used for separation of 30 eral millivolts and several hundreds volts, depending liquida containing various forms of charged particles, for mainly on the feed solution concentration.

many years. The separation methods using electrical en-(5) The smaller the size of the particulate matter and electrolysis, electro-the closer the distance between said particulate matter.

ergy as a driving force include:

dialy*is, ciectrophostsas and cation-and anion-responsive 35 the higher the fractional separation per sinele pa electrodes process, etc. It is important to not that in (6) Liquid channeling. by-passing and back-mixing every known electr cal method of separation, the charged always lower the fractional separation per single pass.

particles contained in the liquid are always selectively (7) ne liquid flow rate has a little effect if any, upon replaced by the applied current' flowing across a pair of the separation efficiency.

electrodes, viz., cathode and anode, according to their 60 separation efficiency:(8) The valency of the io polarities. Therefore, the rate of removal or separation is the' higher the valency, the higher dependent upo the current that is flowing across said pair the separation etliciency. The dielectric constant of the solute to be removed seems to heve the same effect.

of electrodes.

But, in the separation method provided by the present (9) When the particulate matter in the bed is com-inventiort, said charged particles or/and said n o!ccules 05 pletely saturated with the solutes and no further separ form double layers at and near the surface of said electro-tion is obtained, the liquid drained from said bed (after statically charged particulate matter after having replaced having turned off the applied electrostatic charge) is themselves from the liquid bulk. and are held within ihne usually in or near saturation with said solutes.

double layers until the applied electrostatic charce is The double layer formation for a stationary co!utio turned otT: and they are not selecdvely separated accord 70 has been prosen beyond any doubt: but its formation a ing to their poLatit4es, as is being done in every known retention on a charged surface in a mosing coiution has separation method usirs electrical energy. In the separa-not been c!early demonstrated. previously. This mventor has found experimentally thr.: a double la>cr can be re.

868 340

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4 tained within a viscous liquid film adjacent to a charged ized by said liquid in a bed which is charged by an ap-surface placed in a moving solution. Since for most of plied electrostatical potential using a suitably designed th'e liquids the magnitude of the effective thickness of a electrode. A part of said particulate matter m the bed viscous liquid film is approximately % cm, and the may be a!! owed to leave said bed with the efMuent of said magnitude of the effective thickness of a double layer is liquid: and the removed particulate mat:er is then sepa-5 usually much less than % cm., the retention of a double rated from said liquid cliluent by filtration or settling.

layer within a viscous film at a charged surface in a mov-This method provides a true contmuous operation, smce ing solution is quite practicable.

the removed particulate matter may be regenerated and In a packed bed of electrostatically charged particulate returned to the system continuously, matter, the magnitude of the average dimension of pore in O) Said finely divided particulat; matter may be spaces is approximately equal to the average size of the packed in a deep bed allowinc said liquid to freely dow particulate matter packed. Therefore, if the aserage uze through the bed while it is charged by an applied elec-of the particulate matter packed in a bed were less than statical potennal using a suitably designed electrode. All tbs effective thickness of double layers formed, then the the charged particles or/and polarizable molecules in said pore spaces of the bed may be considered to be complete g, liquid will be brought into intimate contact with said par-ly filled with double layers. Therefore, the charged parti-ticulate matter while said liquid is passing through the cles in the solution passing through the packed bed of narrow port spaces of said bed, and are attracted by the particulate matter having an average size less than the applied electrostatic charge at the surface of said particu-effective thickness of the double layers that have been late matter, forming a double layer around each particu.

formed by an applied electrostatical potential would have.n late matter and thus filtering out said liquid. This method 2

little chance to leak through the bed without being caught may be called "lon Filtration

• since it opera'es as the or-and held within said double liters. Since a bed would be dinary filtration does. Because of the above described res-saturated by the charged particles from the solution inlet-sons this particular method of separation provided by the end, the depth of said bed can play an important role in present invention has been found most desirable. It can be determining the fractional separation of solution per 23 carried out in the manner of a cplic operation. The com-single pass.

plete cycle including the filtration and the bed.regenera.

To summarize that already described above, it may be tion can be carried out in the same apparatus by simply sud that the present invention has several unique and de-turning on the applied electrostatic charge for filtration sirable features as a separation method. namely: (1) sery and turning the rame off for bed. regeneration. Like the rapid and complete separation (2) negligible power re-30 ordinary filtration, liquid channeling, by-passing and back-quirements as compared to all the known electrical sepa.

mixing within the packed. bed can loacr the separation ration methods. O) in=tantaneous and complete regenera-efficie: cy. It has also been found esperimentally that the tion of the separation column, (4) no secondary stream applicatron of too hich an electrostatic potential to the disposal problems, (5) extremely simple apparatus and bed can cause an intensive repulsion between the particu-operational procedure, (6) great flexibility and applica. 33 late matter packed in bed and results in dispersion of bility, suitable for separating practically any liquid con.

liquid, causing poor separation.

taining charged particles or/and polarizable mo:ccules at in the above methods (I) and (2), the particulate mat-any concentration.

ter removed from the system may be regenerated in a sep-Because of the unique features described above, the arate apparatus by either washing away the colute held present invention should be particularly attractive in puri-40 on to it or by charging it with an applied electrostatical

,fying, separating, d Iuting or concentrating electrolyte so-potential, preferably of the polarity opposite to that used lutions, in desalination of sea water, in water quality con.

for contacting.

trol, in liquid-waste treatment, and as an anal >tical tech-EXPERIMENTAL f

nique for liquids and liquid sohytions.

Numerous experimental runs have been carried out suc-Nowhere in the literature as there any report on the 43 cessfully by employing various solid-liquid contacting use of double layer formation brought up by an ' applied methods including the three methods described above.

electrostatical charge to the surface of a particulate The separation method (3) described above has been matter suspended in a liquid or packed in a bed to facili-found most desirable: a typical experimental system em-tate the continuous contact between said liquid and said played and several typical experimental runs are described electrostatically charged particulate matter and to effect 50 below.

the separation of the charge particles or/and polarizable Referring to FIG. I, the How-sheet of a typical experi-snolecules contained in said liquid. The filtration of a dis-mental system used, a Pyret-glass column ( A) is packed solved electrolyte or/and polarizable molecules from their with graphite powder (97'S pass through a #325 Taylor solution freely Howing through an electrostatically Screen) to a depth of 24 in.: an electrostatic charge of the charged bed of particulate matter has not been feasible 53 desired polarity and voltage can be applied to said bed previously.

from a D.C. power supply (B) through an electrode wire According to the present invention there are a number Inserted into the entire depth of said bed; the other termi-of preferable ways by which a liquid containing charged nal having the opposite polarity is grounded, and the bed particles or/and polarizable molecules may be brought is completely insulated from the ground. A feed solution into intimate contact with electrostatically charged par-60 containing charged particles or/and polarizable molecules ticulate matter te c;Tect the separation of said charred of the desired concentration is fed to said column (A) paricles or/and said polarizable molecutes from said from a tank (C) through the inlet (D) located near the liquid.

bottom of said column; the' flow rate is controlled by a E.tamples are:

valve (E) and read by a rotameter (F). After having (I) A finely divided pariculate matter may be suspended GJ passed across the entire depth of said graphite bed, the in said liquid containing charged particles or/and polar-solution leaves tid column from the outlet (G) located izable molecules by <fow rnechanical acitation of said near the top of -aid column. and its concentration is and liquid to facditate intimate contact between the two; said

!) sed by an auw natic analytical instrument (H), s.rch as particulate matter is electrostatically charged by an ap-conductivity anal ser, pH analyser or any witable chemi-3 plied c!ectrost.itical potential tpositive or negative) using 70 cal analyser, and recorded continuously by a recorder (D; a suitaHy designed electrode placed in said liquid. Fol-the effluent is then !cd to a receivine tank G). When the lowine this contacting oyration. Said particulate matter effluent concentration indicates that the breakthrouch may be allowed to settle or lilter out said liquid. This point has been reached within said bed and the graphite method is a batch wiw operation.

powder has been saturater with the solute the feeding of CJS.JJ linely disided particulate matter may be fluid- :s solution is stopped and the app!ied c! cirostatic charge is 868 W

3,790,461 then turned off; the liquid contained in the bed is then within th' bed of graphite, viz., channeling, by. passing e

rained completely from the bed through the outlet valve and back. mixing, etc., as already described above.

). Tbc entire procedure desenbed above is repeated to continue a continuous cyclic operation. When a true EXPE RIMENT T

g{ g,g ORGAN SOLtJTIONS 9

o g g,ES cont:nuous operation was desirable. two or more filtra.

5 tion columns were used; therefore, at least one column is go,,p.,

gun,p.,

go,,p.r; always turned on to permit a continuous flow of liquid when others are turned off for bed. regen.eration.

Feat soluuon, s.000 Feed molation. s mo Feed solution. s.mo For each experimental run, the separation emeiency per

.,n.m. of ru.tro.han-p.p.m. of natroten.

p.p m. of natronen.

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sene m totum.

single pass of liquid was determined by the simple graphi. Io Qta'jg,D"*8. +1" V,Tc7P*1-3" M'g,Q,""*

cal integration of the concentration-time curve and ma.

Feed rate. eo m1J rmt rate. co m1J F-s rate, so mt.i terial bala..:e. The power requirement for each run could

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only be shown by the wattage needed to operate the rtree cone.

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Time cone.

power supply used to apply the electrostatic charge since traina (Sp.m) ten.)

(p an)

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(p p.mJ the current flowing from the power supply to the experi.15 o.....

am o

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gam mental system was so negligtble that it was not possible to y,,- ;,,-,-

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a. im ao.

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4.se wattmeter for all the runs made in a range of the applied g- - ----

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{$ g-electrostatical potential (relative to the ground) between no:::::':*

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4. im zero and 2 60.000 volts. All the experimental runs were 20 E::C IE E'...:.". IS k.__..

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a. sn no......

s. 30u in the following examples to demonstrate the separation 25

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characteristics of the present inventio,.

IXFERIMENT 3.-8 EPA RATroN OF 80DitTM CHLORIDE De maaimum fractional separation for the above three soLUTtoNs runs, #P-1, #P-5, #P-A7 were 50"e, 46% and 24%

respectively; the corresponding separation emeiencies were Ron 1 Run s Run17 30 44%,4I"e and 20"e respectively. In an alternating field Fmt eoncentracon, Femt eoncentnuon, Feed eoncentradon, the molecules experience the polariaation resulting from 200 p.p.m.

se p.p m.

i. coo p.p.m.

both the permanent dipole moment and the induced dipole.

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Fans rate, a.sm Feed rate, s.sm Fews rate. sJiao which will oscillate instantaneously with the field, whereas nusniassar munun./sor mumiassoft.

35 the polarization resulting from the permanent dipole mo.

rune cone.

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Time cone-

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The rate of migration may be slowed down by their rota.

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tional motion: and this effect may account for the lower o.

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It is obvious from the above example illustration and

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replacing remaining liquid,in the bulk from said particu-ro:":":

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se required for running the power supply used, provided that the liquid separation system is electrically insulated from the ground. The optimum electrostatical potential to be The average minimum concentration of the emuent In each run was used to determine the maximum frac-55 applied will mainly depend on the concentration of solu.

tion and the valency or the dielectric constant of the solute tional separation per single pass of liquid and the separa.

to be separated. In general, the higher the valency or the tion emeiency before the breakthrough point. For Rua dielectric constant, the lower the electrostatical potential

1. 1, the maximum fractional separation of 90% and the required; also the higher the concentration, the lower the seperation emciency of 86" were obtained; for Run #4, 60 potential needed for the same separation results desired.

the maximum fractional separation of 74% and the sep-It will be understood that this invention includes separa.

aration emeiency of 65" were obtained; for Run #17 tion of all the liquids contaming any sort of charged the maximum fractional separation of 55", and the sep.

particles or/and molecules' having polar or/and polariz-aration emciency of 45"o were obtained. The above re.

able properties, as long as a double layer or layers of sults indicate that.f the depth of graphite bed were made 63 said charged particles or/and said molecules having polar three tirnes as great as that used, a feed solution of I.000 or/and polaritable properties are formed at the surface p.p.m. Nacl would have been completely separated into of a solid by the induction of,an applied electrostatic Nacl and water. The solutions dramed from the bed dur.

charge to said solid, i order to facditate their separation ing the bed regeneration were in or near saturation for from their mother I.

id. The induction of the double Run #4 and Run #17, but not for Run #1, which had To layer formation. a confaradaic process. is the Ley to sepa-been discontinued before the bed breakthrough point was ration of liquid by the present invention. Therefore, the actually reached. The wattage of the power suppiy used occurrence of any faradaic process. i.e., electrolysis, elec.

for each run was 45 watts. It is interesting to note that the trodialysis, electrophoresis, and electroplatine, etc. should small Munctuation in the emuent concentration obtained be prevented in the separation method provided by the may have been caused by some nonideal flows of liquid 75 present invention.

300R ORGINAL 868 m

3,790,461 7

8 Having thus described my invention of what I claim charge and separating said substances adhering to said as new and desire to secure by Letters Patent is:

particulate matter.

1. Method for treating a liquid containing substances

g. The method of claim I wherein a negative electro-including charged particles or/and molecules having polar static charge is applied to said solid conductor.

or/and polarizable properties which are capable of being

9. The method of claim I wherein a positive e?cctro-3 attracted by an electrostatic charge and the resultant static charge is applied to said solid conductor.

electrostatic field, said method comprmng: ( A) intimately

10. The method of claim I wherein an electrostatic contacting said liquid, in a contact zone electrically capa-charge of alternatingly negative and positive polarities is ble of conta:ning an applied ciectrostatu: charge, and in applied to said solid conductor.

the absence of a flow of electric current within said con 10 tact zone, with a finely divided solid conductor carrying References Cited an applied electrostatic charge thereby to induce the ad-UNITED STATES PATENTS herence of at least a layer of said substances on said solid cenductor by means of the applied electrostatic 799,605 9/1905 Lester -- -

_ *04--149 I,038,122 9/1912 Hagg. ---

204 - 149 charge; and (B) separating from saA miid conductor a i5 liquid having a reduced concentration of said substances.

2,4:g,3 9 9/3947 Ham et al......... 204-180 R

2. Method according to claim 1, wherein said solid 2,563,903 8/1951 Zadra...___....... 204-109 3,457.152 7/1969 Maloney, Jr. et al.... 204--131 conductor is in the form of finely divided particulate 3,616.356 10/1971 R oy ___ _ ___..

_ 204 - 152 matter.

3. The method of claim 2 wherein said contacting of,

2,914.453 11/1959 Wennerberg........ 2M-186 said liquid with said particulate matter is accomplished -

3,304,251 2/1967 Walker et al... ___... 204--184 by agitation to suspend said particulate matter in said 3,544,441 12/IM O Griswold ___..... __ 2(M--18 6 liquid.

3,655,550 4/1972 Davies

_ 204 - 302

4. The r.actbod of claim 2 wherein said contacting FOREIGN PATENTS of said liquid with said particulate matter is accomplished *5 by flow of said liquid through a bed of said particulate "

648,201 1/1951 Great Britain _____... 204 - 149 matter to fluidize said particulate matter.

5. The method of claim 2 wherein said contacting of OTHER REFERENCES said liquid with said particulate matter is accomplished Le Golf et al.: " Applications of Fluidized Beds in Elec-by transporting said particulate matter through said liquid. 30 trochemistry," Indust. and Engin. Chem., vol. 61, No.10,

6. '!he methc4 of claim 2 wherein said contacting of October 1969, pp. 8-17.

said liquid with said particulate matter is accomplished by permitting said liquid to flow through a bed of said par.

JOHN H. M ACK. Primary Examiner ticulate matter.

A. C. PRESCOTT, Assistant Examiner

7. The method of claim 2 wherein said particulate 35 matter, after contacting by said liquid and separation of a U.S. Cl. X.R.

liquid having reduced concentration of said substances, is 204 - 186, 149 regenerated by discontinuing said applied electrostatic e

4 868 74 o

United States Patent ti91

[iii 4,066,526 Yeh (45]

Jan.3,1978

[54] ME1110D AND APPARATUS FOR 3,154,682 10/1964 Hartz et al.

55/2 E:.ECTROSTATIC SEPARATING 3,496,701 2/1970 Derg 204/186 DISPERSED MATTER FROM A FLUID 3,544.441 12/1970 Gnswald 204/186 3.733,784 5/1973 Anderson et at 55/138 MEDIUM 3.790,461 2/1974 Yeh 204/180

[76] Inveator: George Chinyou Yeh, Smedley Drive.

FOREIGN PATENT DOCUMENTS R.D.1. Newtown Square, Pa.19073

$81.530 9/IM4 Frana 55/131

[21] App;. No.: 498,423 Primary Examintr-Bernard Nozick

[22] Filed:

Aug.19,1974 Attorney, Agent, or Firm-James Albert Drobile

[$ i] Int. Cl.2 B03C 5/00

[$

ANC

[52]

U.S. Cl.

204/186; 55/2; 55/127; 55/131; 55/152; 2N/302 Herein are disclosed a method and apparatus whereby

[51] Fleid of Search.

2N/186-191, dispersed matter in the form of finely-divided particles, 2N/302; 55/2,127,131,138,146,150-157 and/or in the form of molecular species such as inole-cules, and stoms are separated from a gaseous or liquid

[56]

References Cited medium by subjecting same by a corona discharge via a U.S. PATENT DOCUMENTS perforated separating electrode to repel same and con-1.427,170 9/1922 Fortescue 55/138 tinuously removing the charged matter.

L il6,?O9 5/1938 Cottrell 205/188 1.074.170 t/1963 Carswell et at 204/181 8 Claims,3 D iag Figures 200ROR81ML

/

ELECTROSTATIC CHAEE GENERATOR tie M

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j P90RORGEL 4,066,526 1

2 nique heretofore known. Therefore, molecular species men {OD AND APPARATUS FOR other than those adsorbed on the collected particulate ELI'CIROSTATIC SEPARATING DISPERSED matter cannot be separated from the fluid medium, since MATTER FROM A FLUID MEDIUM the ionized molecular species would be neutralized on 5 the collecting electrode and remain free within the fluid 13ACKGROUND OF TIIE INVENTION medium.

SUMMARY

OF TIIE INVENTION v uon rela to the separation of dispersed matter from a liquid or gaseous medium through the use This invention is directed to a method and apparatus cf an e!cctrostatic force. More particularly, the inven.10 for separating dispersed matter, specifically finely-t:on is d rected to a new and improved method and divided particles and/or molecular species (hereinafter, appantus for separating dispersed tnatter, consisting of

" molecular species" is intended to mean and include finely-div ded particles and/or any ionizable chemical any ionizable chemical species such as molecules, atoms species scch na molecules, atoms and radicals (such and radicals), from a gaseous or liquid medium, by the species being hereinafter referred to as "molesular spe-15 use of an c!cctrostatic repulsive force, rather than cies"), from a fluid medium by means of an electrostatic through the use of the electrostatic attractive force repuls:ve force.

which is utilized in all conventional electrostatic separa-

2. Description of the Prior Art tion techniques and apparatus.

In the consentional electrostatic precipitation of par.

The present invention is directed particularly to a neulate rr.atter from a flu;d medium, it is well under-20 method and apparatus for separating or fractionating smod that separation of the particulate matter in the dispersed matter, consisting of particles and/or molecu-fiuid is achieved through the following three basic lar species, from a fluid medium. The method of the steps: (a) electrostatsc charging of particulate matter present invention comprises electrostatically charging with a discharging electrode, (b) collecting of the said particles and/or ionizing said molecular species (if charged ; articulate matter with a grounded electrode, 25 such, respectively, are not already charged and/or ion-at:d (c) removal cf the collected particulate matter from ized), and then passmg the fluid medium and dispersed the groun ded electrode. Since the ultimate separation of matter through a suitably constructed, filter-like elec-the particulate matter from the fluid is accomplished trode (hereinafter, the " separating electrode") which is enly whe1 the collected particulate matter is removed pervious to the passage of fluid medium and such dis-from he collecting electrode and placed outside the 30 persed matter, and which is generating a corona dis-elec:vsta:ic precipitator, the insufficient retention of charge of the same polarity as that of the charged parti-the particulate matter in the applied field, and the re-cles and/or the ioruzed molecular species. In a typical entraimnent into the fluid stream of particulate matter emM--ent of the apparatus of the present invention, which alt:sdy had been collected, would result in poor the separating electrode is consaucted in the form of a separation efficiencies.

35 futer utilizing a fine wire mesh (or coil, cloth, felt, thin The above two difficulties are minimized by the use packed layer or the like), or a porous metal piate having oflow fluid velocities, and by the continuous removal pointed exterior surfaces, and is capable of being elec-cf the co.lected particulate matter from the collecting trostatically charged and of providing a corona dis-clectrode As a result of these lunitations, however, the charge, in response to such charging, from its exterior uze, the complex 2ty and the cost of an eflicient electro-40 surfaces which are in contact with the oncoming stream static..e:ipitator typcidly are very great.

of fluid medium and dispersed matter.

The so<alled " electrostatic filter", such as one dis-The separation aclueved by the method and apnara-closed in U.S. Pat. No. 3,544,441, issued to E. A. Gns-tus of the present invention is effected by the strong wold on Dec.1,1970, may increase the degree of parti-repulsive force which eaists between the aforemen-cle reten ion in the electrostatic field, and so reduce 45 tioned corona discharge, on the one hand, and the substantidly the particle re entramment into the fluid.

charged parucles and/or ionized molecular species of Ilut, perndic removal of the collected material is re-the same polanty, on the other hand, when the fimd quitec, as is frequent cleaning of the porous matrix medium contaming dispersed matter is subjected to the which is ased. Furthermore, due to the high concentra.

field of the corona discharge in being forced to flow tica and ;ong retention of the charged particles in the 50 through the separating electrode. The separating elec-tield iea-the collecting electrode, abnormal particle trode theoretically allows only the uncharged fluid chargmg and resultant undesirable separation charac-medium to pass through, and rejects all of the charged reristics in the apparatus would be inevitable. These partic!cs and ionized molecular species of the same phencme ta might include back corona discharge, the polanty as the electrode. As a result of this repulsion lowering of the spark-over voltage, the suppression of 55 and selective rejection, the separation of said charged particle charging, and the like.

particles and/or said ionized molecular species from the It is most important to note that, in every conven-fluid medium is accomplished.

tional ele:trostatic separation technique, the particulate In the separatien method and apparatus provided by natter is charged by the discharging electrode, and the present invention, the complete and ultimate separa-attracted to the collecting electrode by which the parti-60 tien of the charged particles and/or the ionized molecu-cles are :4paraud from the fluid. In other words, the tar species occurs at the discharging electrode (accord-collectin;; electrc4e is acting as the separating elec-mg to the present invention, synonomous with the so-trode. It thus is the electrostatic attractive force be-called separating electrode) due to the electrostatic tween the charbed particulate matter of one polanty repulsive force. Such separation is not due to any elec-and the collectmg electrode of the other polanty that 65 trostatic attraction for e. For this reason, ionized mo-constitutes the driving force for the separation in accor-tecular species as well as charged particles can be sepa-ilance with conventional techrusues. The electrostatic rated by practice of the present invention in contrast to repulave force is not unlized in any separation tech-prior techniques. It thus is essential to keep in mind that 868 345

~

j.

4,066,526 separation is effected bv the discharging electrode (i.e.,

than the electrostatic attractive force existing between the senarat ng electrode), and not by the collecting the charged particle (or ionized molecules) and the electrcde, and that the driving force 'or such separation collecting electrode in a far longer range, as is usually is the electrost:itic repulsive force and not the electro-the case in the conventional electrostatic precipitator.

ani stati: utractive force.

5 This inventor has concluded that the above facts enable int

, In the "ciectrical double-layering technique for lig-charged particles and/or ionized molecular species to und sep ratica developed by the present inventor and be rapidly and completely separated from a fluid me.

tal disclosed in U.S. Pat. No. 3,790,461, issued Feb. 5,1974, the ungle electrode therein required also constitutes the dit'm in accordance with the present invention, ph separating electrode. However, the dnving force for 10 Because of the novel separation pnnciple of the pre-ser forming the electrical double-layer utilized in the sepa-sent invention, the method and apparatus provided by me ration of charged particles and/or polanzable mole-this invention should be capable of separating and frac.

t3e cules is the electrostatic attractive force, and not the ti natmg virtually aH types and sizes of particles, and all electrestatic repulsive force. For this reason, the re-m lecular species which can be ionized, from a fluid me mosal of the collected material frorn that electrode is 15 medium in which they are originally contamed, even usi required as in all other heretofore-known electrostatic under bperational conditions that would preclude their CYl separation methods.

separation by conventional electrostatic separation The electrostatic repulsion between two charged techniques. The present invention permits of a com-tus bodies of ident; cal polarity is a well.known phenome-plete, rapid, economical and truly contmuous separa-

'8E non. However,it has never been demonstrated that this 20 tion of particles and/or ionizable molecular species at electrostatic repulsive force could be utilized to sepa-'

from a fluid medium. A few illustrative applications of CI' rate charged particles and/or ionized molecular species this invention are: indoor ar.d outdoor air quality con-from a fluif medium in which they were originally trol; separation or fractionation of mixed particulate I:

contained. ~his repulsive force can be so uti'ized if the matter and/or ionizable molecules: punfication of air discharging ele: trode is cor.structed and con 6gured so 25 and other gases; removal of particulate matter from a as to be adapteil to generate a dense and uniformly-dis-high velocity fluid stream at high temperatures and tributed corons discharge from its exterior surfaces, in pressures with negligible pressure drop; and the like.

which case it tnen also can function as the separating electrode in accordance with the present mvention.

A particular advantage of the method and apparatus This inventor has determined expenmentally that a 30 of the present invention is that, since separation is ac-discharging ele: trode, constructed in the form of a fine complished by repulsion forces rather than attraction wire tnesh or cloth, or of a pcrous metal plate having forces, the separating electrode does not tend to become tw many pointed surfaces, can generate a screen of dense f uled by the material being separated.

co and umfarmly listnbuted corona discharge which can It is a primary object of the present invention to pro-ad not only charge dispersed particles and/or ionize mo-35 vide a simple method and apparatus for electrostatically 1,

lecular species, but can also selectively reject and filter and continuously separating or fractionating chargeable str out the charged partic!cs and ionized molecular species particles and/or ionizable molecular species from a fluid im of the same pelanty. For example, a 400-mesh stainless medium in which they are contained, with a greater co steel clath, w!uch is made of fine wire having a diameter separation efTiciency, and at a lower cost and space du of 10 mils <0.010 inches), and which has an average 40 requirement, than heretofore has been attainable trc openity; of !$ ttils (0.015 inches), can be used as a dis-through the use of known techniques.

wi charging (and separating) electrode to generate a co-It is another object of this invention to provide a in rona d.scharge of a current density of a few miniam-simple method and apparatus for electrostatically and pri peres per square inch of its surface area. This corona continuously separating or fractionating chargeable co discharge can effectively charge graphite powder 45 particles and/or ionizable molecular species under the (ninety percent (90%) of which will pass through the operational conditions which make separation by con, an sarne 400-me h stainless steel cloth), and can completely ventional electrostatic separation techniques impracti.

sp.

prevent the penetration of the Eraphire powder through cable or entremely difficult.

ra' the cloth w1en the graphite powder is dispersed in an It is still another object of this invention to provide a P1 air stream mov ng through the 400-mesh stainless steel 50 cloth at a velocity as high as 110 feet per second.

simple method and apparatus for effecting mass trans.

IC' fer, and/or mass transfer accompanied by chemical pl8 r urther esperimental studies of a sunilar nature were made using vanous types of particulate matter, various reaction, between fluid molecules and particulate mat.

ap separatmg electrode configurations and construction ter (either solid or liquid), and the subsequent separation materirls, and "arying electrical loads. The same or a 55 of the mixture of reactants and products after the con-

• I

• I sulntar> ttall) sirnilar phenomenon was observed each tacting between the two. In this case, the apparatus ttme. From '.hese exploratory studies, the present inven.

provided by this invention is not only a contacter or pa ter has cetermrted that the electrostatic repulsive force reactor, but also a separator at the same time, co acting en a panicle of very small size (i.e., of a few It should be understood that the finely-divided partic-microns or less in diameter), and on ionized molecular 60 ulate matter which can be separated from a fluid me-ci, species, is many thousands of times greater than the dium through practice of the present invention includes di3 inertial and viscous forces of the fluid medium acting on microorganisms such as bactena, viruses and the like.

pe the same particle or molecular species in a given system.

Accordmgly, a further object of this invention is to pr provid-d a well-cordtructed dischargmg (separating) provide a simple method and apparatus for etTecting a ch electroae and s sufficient electrical load are utilized. 65 rapid and substantially complete separation of micro-fr<

Under these conditions, the electrostatic repulsive force organisms and the hke from a fluid medium in which ar of the corona d:scharge acting on a charged particle or they are dispersed, i c., a disinfection of said fluid me.

nc ionized molect.ar species in a short range is far greater dium, in an conomical and truly continuous manner.

er.

868 M6

n:

4,066,526 As noted above, separating electrode 20 is pervious to BRIEF DESCRIIrTION OF THE DRAWINGS the passage of fluid medium and dispersed matter, and The accompanying drawings illustrate the method must be fabricated so as to satisfy that requirement. Any ami several embodiments of the apparatus of the present materulof construction which is conductive to electric-5 ity, and which will permit of the passage of fluid me-invention.

FIG.1 is a partial section of a simplified, esperimen.

dium and dispersed matter, is suitable for use m, the tal apparatus accordmg to the invention, using a single-practice of the present invention. Porous metals and plane separating electrode for separation. FIG.1 also wire screenmg are particularly useful. In the experimen-serves to illustrate, schematically and in a very funda.

tal apparatus to which reference already has been made, mentat way, the basic steps comprising the method of to the separatmg electrode 20is constructed of four super-imposed layers, each layer being 12 inches by 8 inches, and fabricated from a 400. mesh stainless steel cloth.

F G.

partial vertical section of another exper,

When molecular species rather than dispersed particles mentally-tested apparatus acu ding to the invention.

were being separated in this experimental apparatus, the using a single cylindrical sept.ating electrode inside a 15 separatmg electrode 20 consisted of a 12-inch by 8-inch cyclone-shaped collecting electrode.

' piece of porous sintered stainless steel having a porosity F10. 3 is a partial vertical section of another appara.

tus embodiment of this invention, using several separat-Of. 60 volume percent and an average pore size of 20 ma a ing~ electrodes in series for the purpose of fractionating parating electrode 20 is connected by electrical a miature of particulate matters and/or molecular spe-a to med pramfele ctes.

static charge 25, such as a high-voltage power supply.

DETAILED DESCRIPTION OF THE Separating electrode 20 is connected to a termmal of the INVF,NTION (INCLUDING DESCRIFTION CF generator 25 (e.g., high-voltage power supply) having PREFERRED EMBODIMENTS) the desired polarity, and the other terminal (having the 25 opposite polarity)is connected to electrical ground 35

.ne invention new will be described in detail, by through electrical conductor means 26 and 28, as retere1ce to the several specific embodiments shown m shown. Collecting electrode 30 is shown as connected the accompanying drawings.

through electrical conductor means 27 and 28 to electri-As noted, FIG.1 illustrates the practice of the cal ground 35. The generator of electrostatic charge 25 mrtbc d of the present invention, through the use of one embo timent of the separation apparatus of the inven 30 employed with this apparatus embodiment was a high-voltage power supply capable of reversing the polarity tien. As shown m FIG.1, the separation apparatus and of generating voltages in the range between 0 and consists of a rigid enclosure 10 defunng a chamber 15 plus or minus 60 K.V. (kilovolts).

adsp d for containing a flu:d. As also mdicatea m F10. 0 includes access means 12 for introduc.

1, portions lla.11b and 11e of enclosure 10 are con 35 ng fluid medium containing dispersed matter into zone struct:d from a dielectric material, i.e., an electncal A of chamber 15, and access means 13 for withdrawing, insulation material, while porton 30 of enclosure 10 is from zone B of chamber 15, a fluid medium containing constmeted from a material which is electrically con-the reduced concentration of dispersed matter. Enclo-ductive. Portion 30 of enclosure 10 constitutes an elec-sure 10 also includes wwmeans 14 for withdrawing, trode, viz., the collecting electrode" in accordance 40 from zone A of chamber 15 dispersed matter in a rela-with the invention. The use of a conecting electrode 30 tively conce.tntted form.

in the method and apparatus of the present invention is In accordance with the method of the invention, as prtferable but not essential, and enclosure 10 may be practiced with the apparatus illustrated in FIG.1, a constructed exclusively from dielectric material-fluid medium containing dispersed matter consisting of 0 may be of any desired size and shape, 45 fmely divided particles and/or molecular species is and rtay be constructed of.any suitable material. In one introduced to zone A of chamber 15 through access specific embodiment, utilized as an experimental appa-means 12. The dispersed particulate matter is not elec-ratus, the enclosure 10 was fabricated entirely trom trostatically charged, and the molecular species are not PLEXIGLASS methyl acrylate pir.stic, except for col-ionized, prior to their introduction to zone A of cham-lecting electrode 30 which was fabricated from steel 0 ber 15. Said particles are electrostatically charged, and 5

pl.ite. The size of enclosure 10 in that esperimental said raolecular species are ionized, by being subjected to apparatus was 8 inches by 8 inches by 10 inches high.

the field of the corona discharge provided by discharg- 0 contains a separating electrode 20, ing and separating electrode 20. Upon becoming so which separates chamber 15 into zones A and B, and charged and ionized, the dispersed matter is s:lectively which contains apertures 21 renderingit pervious to the 55 repulsed by the corona discharge of separating elec-passage of fluid medium and dispersed matter. Separat-trode 20, and is collected adjacent grounded collecting ing electrode 20 also is adapted in its construction and electrode 30 and continuously removed from zone A of configuration to produce a suitable corona discharge in chamber 15 through access means 14. A fluid medium response to being electrostaticauy charged to a suffi-containing a substantially reduced concentration of cient degree. (Separating electrode 20 also serves as the 60 dispersed matter is passed through apertures 21 of sepa-ducharging electrode in those instances where the dis-rating electrode 20 and into zone B of chamber 15, and persed matter has not been charged and/or ionized is continuously withdrawn from zone B through access prior to being subjected to the field of the corona dis-means 13.

charge.) Separating electrode 20 is electncally insulated For the separation of molecular species in particular, from enclosure 10, by virtue of the fact that ends 20a 65 the fluid medium which is transporting the dispersed and 10b of separating electrode 20 are embedded in matter including molecular species is split between the non-conductive portions 11c and lib. respectively, of two ex2t streams in a fixed ratto, and is withdrawn con-enclo4ure 10.

tinuously from access means 13 and 14 in that ratio. This 868 347

ex - s 4,066,526 technique prevents or minimizes possible abnormal ion-annular sealing ring 45, which was constructed of fibre.

C' ization in the apparatus.

glass in order to insulate the separating and dischargmg d

For the separation pnmarily of finely-divided parti-electrode electrically from the collecting electrode 60.

e

.:les, the fischarging and separating electrode 20 is con.

He bottom opening of spool 51, as defined by lower iected to either the negative er the positive terminal of 5 flange $1b, is covered by a 400-mesh stainless steel 8

L-the elect ostatic charge generating source 25, although cloth. The glass spool 51 remains open at the top, to 2 discharge of negative polanty has been found to be the define access means 43 through which the fluid medium 8-more efketive in most instances and is, therefore, pre-coctaining a reduced concentration of dispersed matter Jerred. For the separation of molecular species, the is withdrawn. The stainless steel screen 52 and the stam-polanty of the corona discharge is determined by the 10 less steel coi! 50 together function as the separating and I

electroc affmi y and/or the ionization potential of the discharging electrode. De electrostatic charge genera-earticul.sr molecular species to be ionized and sepa-tor 55 utilized in the experimental apparatus typifying rated. In general, a corona discharge of negative the apparatus of FIG. 2 was identical with that used m polanty is employed with electronegative molecular the experimental apparatus illustrated in FIG.1.

apecies, and a corona discharge of positive, polarity is 15 In the apparatus of FIG. 2, access means 41 are pro-employed with electropositive molecular species in-tided in enclosure 40 for the introduction of fluid me-eluding positive ions.

dium containing dispersed matter to chamber 46. As j

FIG. 2 illustrates the practice of the present invention shown in FIG. 2, wm means 41 enter enclosure 40 m anoth.:r apparatus embodirnent, and specifically in tangentially, so as to impart a swirling motion to the another actual expenmental apparatus. In FIG. 2, en-20 entering stream for the purpose of improving the ef!i-closure 40 also constitutes the grounded collecting c!cc-ciency of separation. Access means 41 also permit of the trode 60 As indicated, enclosure 40 (co!!ccting elec-separate introduction of fluid medium at 41a, and of trode 60s is fabricated entirely of an electrically-cen.

dispersed matter at 42, prior to their being mixed in ductive naterial, and consists of a cylindrical upper portion 41b and introduced to chamber 46 of enclosure portion 60a and a conical bottom portion 606. Enclo-25 40. On the other hand, a fluid medium which already sure 40 (collecting electrode 60) is connected to ground contains dispersed matter can be introduced into wm 65 through electrical conductor means 57 and 58. En.

means 41 at 41a, and will proceed through portion 41b closure 40 defines internal chamber 46, which is adapted of access means 41 into chamber 46 of enclosure 40.

~

to contain a fluid. In the specific experimental apparatus 0 also is equipped with access means 44, for

o which reference is made above, the enclosure 40 is 30 withdrawing dispersed matter fabricated from sheet steel, and has an upper cylindrical In operation, the apparatus illustrated in FIO. 2 is in ponion o0a which is 12 inches in diameter, a lower all material respects identical to the method of opera-cylindrical portian which reduces to a diameter of 3 tion of the apparatus illustrated in FIG.1.

mehes, and an overall vertical height of 3 feet from the FIG. 3 illustrates yet another apparatus embodiment bottom cf the conical portion to the top of chamber 46 35 which is useful in the practice of the method of the sat sealing ring 45 in FIG. 2).

present invention. In FIG. 3, the separation apparatus As also shown in FIG. 2, the separating electrode comprises vertical enclosure 70, def' ing an internal m

(which ntso may serve as a discharging electrode when chamber 95 which is adapted to contain a fluid. Enclo-the dispersed matter as introduced is not electrostati-sure 70 consists of cylindrical side portion 90a, bottom cally charged and/or ionized) consists of a combination 40 portion 90b and top portion 90c. each of which is con-of a coil 50 of electrically-conductive material, and a structed from an electrically conductive material. Ac-fine-mesh screen 52 of electrically-conductive material, cordingly, enclosure 70 functions also as the collecting both of which are mounted upon a hollow spool 51, electrode 90, which is connected to ground 85 through having f anges $1a and 51bL and which is fabncated electrical conductor means 77 and 78. Chamber 95, from a si.itable dielectric matenal. Spool 51, containing 45 de'ined by enclosure 70, is divided into subchambers the separating and discharging c!ectrode consisting of 95a 956,95c,954 and 95e, by separating and discharg-ccil 59 ar d screen 52, is mounted internally of enclosure ing electrodes 81,82,83 and 84, which are sealed in 40 and within chamber 46 by any suitable structural enclosure 70, vertically, one under the other, by means means such as annular sealing ring 45 which supports of transverse annulir sealing rings 71, 72, 73 and 74, the spacr 51 at flange 51a. and which seals the space 50 respectively. Each of said scaling rings is connected, between spool 51 and the cylindrical portion 60a of near its inner opening, to the base of the corresponding enclosurr 40 (collecting electrode 60). Annular sealmg separating electrode, as at the loci designated 81a and nng 45 is fabricated from a dielectnc material, so as to 81b with respect to separating electrode 81. De annular msulate the elements 50 and 52 of the discharging and sealing rings 71,72,73 and 74 are fabricated from a eeparating electrode from the collecting electrode 60. 55 dielectric material, so as to insulate electrically the sepa-The separating and discharging electrode consisting of rating electrodes 81,82,83 and 84 from the co!!ecting r!ements 50 and 52 is connected by electrical conductor electrode 90. Each of the separating electrodes 81,82, means 53 to caternal electrostatic charge generator 55, 83 and 84 are so constructed, in configuration and mate-the latter device being connected through electrical rial, so as to be pervious to the passage of fluid medium conductcr means 56 and 58 to ground 65.

60 and dispersed matter, and so as to be adapted, upon the In the specific experimental apparatus typifying the imposition of an electrostatic charge of sufficient mag.

apparatu, of FIG. 2, the coil 50 was made of 24-gauge nitude and suitable polanty, to produce a corona dis-ttamless steel wire wrapped around the exterior cylin-charge in polanty identical to that of the charged parti-dncal surface of spool 51, which consisted of a 10 inch cles and/or ionized molecular species to be separated.

long(as measured between flanges 51a and 51b) piece of 65 The apertures providing for the passage of dispersed hollow glass pipe having an outside diameter of 3 matter and fluid medium through separating electrodes inches, and both ends of which were flanged. The up.

81,82,83 and 84 are indicated, respectively, at 86,87,88 permost f:ange 51a of glass spool 51 was sealed to en and 89. Dese separatmg electrodes 81,82,83 and 84 are 868 M8

7 1

4,066,526 l

ccnnected by electncal conductor means 79 through tion of charged particulate matter and ionized molecu-dielectne block 75 to external electrostatic charge gen-lar species is not only practical but economical through l

ersting source 80, which in turn is connected through the practice of the present invention. Funhermore, the ele:tncal conductor means 76 and 78 to electncal results of such work showed that the following separa-grt.und 85, in the same manner as in the apparatus illus-5 tion charactenstics of this invention obtained with re-tra.ed in FIGS.1 and 2.

spect to all particulate matter and molecular species 0 includes access means 96 foi introduc-studied:

ticri of fluid medium contaming dispersed matter, and I. The material of construction and the design of the access means 97 for withdrawal of fluid medium con-separating c!cctrode have a very strong influence on the taimnb a reduced concentration of such dispersed mat-10 characteristics of the corona dischar;;c which is pro-ter Each of subchambers 95a. 95A 95c. and 95d contain duced and, hence, on the separation efTiciency. In gen-access means,91a and 91A 92a and 92b. 93a and 93A eral, the stronger and more dense is the corona dis-and 94a and 94b, respectively, for withdrawing sepa-charge formed, the higher is the separation emciency rated dispersed matter in concentrated fo:.n.

obtained.

In all material respects, the method tp be practiced in 15

2. In every case, the separation emeiency was found the operation of the apparatus illustrated in FIG. 3 is to increase with an increase in the electrical load, result-generally identical to that practiced in connection with ing in a stron6er and more dense corona discharge being the apparatus of FIG.1. Dus, a fluid medium contain-formed.

ing dispersed matter is introduced into subchamber 95a

3. The wave form of the voltage applied, such as of enclosure 70 through access means 96. De dispersed 20 D-C, full-wave A-C, half-wave A-C. and the like, has matter is charged and/or ionized, if necessary, and is little, if any, effect on the separation efficiency. How-seicetively repelled by the field of the corona discharge ever,it was found that very short voltage pulses (e.g., of occurnng first at separating electrode 81. Separated a few micro-seconds or less) seemed to produce a more disxrsed matter is collected near the adjoining portions stable corona discharge, without spark-over between

%. and 90c of collecting electrode 90 formed by enclo 25 the two electrodes, and such practice is to be preferred.

sur 70, and is withdrawn in relatively concentrated

4. The potential gradient existing between the two form through access means 91a and 91A A fluid me-electrodes (where a collecting electrode is utilized) has dium contaming a reduced concentration of dispersed an important efTect upon the separation efficiency, i.e.,

ma.ter is passed through the apertures 86 of separating the greater the potential gradient the lugher the separa-ele.; trode 81 and into subchamber 95A where the same 30 tion efiiciency.

phenomenon is repeated. Ultim tely, a fluid medium

5. A corona discharge ef negative polarity appears to sueitantially free of dispersed matter, or having a sub-give higher separation efliciencies in the separation of stantially reduced concentration thereof, is withdrawn charged panicles than does a corona discharge of posi-fro n enclosure 70 through access means 97.

tive polarity.

nus, it will be seen that the dispersed matter con. 35

6. In the separation of molecular species having a taited in the fluid medium entering the apparatus shown relatively low ionization potential (i e., a relatively in FIG. 3 is fractionated in a stage-wise separation, each great electron amnity), a corona discharge of negative of:uch stages representing a separator embodying the polarity is more efTective and is preferred. Ilowev er, for pruciples of the present mvention. This fractionation is molecular species having little or no electron affinity, a breught about through the use of a series of dischargmg 40 positive corona discharge can be as efTective as a nega.

electrodes, and through utilization of the differing phys-tive corona discharge.

ica' and electncal properties of the materials to be sepa-

7. For a particular electrical loso, smaller particles rated, all of which cause difTerent separation character-are easier to separate than larger particles. His is be-ist es to obtam at each stage. In an exactly similar man-cause the larger particles have a greater tendency to ner. fractionation of a mixture of various molecular 45 clog the discharging electrode when an insuflicient spe:ies also can be accomplished.

electrical load is employed.

De apparatus illustrated in FIG. 3 also may be used

8. The ratio in which the fluid medium is split be-g to treat several feed streams at the same time, simply by tween the two effluent streams, when molecular species presiding access means for the introduction of each of are separated, has a decisive efTect on the separation such streams.

50 efficiency. De smaller the ratio of the stream of fluid it should be emphasized that the grounded collecting medium carrymg the reduced concentration of dis-electrode is not essential to the practte of the present persed matter, to the stream of fluid medium carrying invention, since it is the separating electrode that sepa-the increased concentration of dispersed matter, the

tes the charget* particles and/or ionized molecular greater the separation efliciency. For particle separa-pe:ies. However, the use of a collecting electrode is 55 tion, the faster the rejected particles are removed from dist metly pref:rred. since it facilitates the collection and the apparatus, the greater is the separation efficiency cortinuous removal of the repelled charged particles obtained. ne efTect seems to be identical for the separa-andor iordzed molecular species, and thus prevents or tion of molecular species, and suggests that the high redaces abnormal charging or ionization which would concentration of the charged particles or ionized molec-lower the separation emeiency. Funhermore, by 60 ular species in the apparatus can cause abnormal charg-drounding the apparatus through the collecting elec-ing or ionization, thus lowenng the separation em-trcile the safety of the operator may be secured, espe-ciency.

cially if the apparatus is not a perfect Faraday cage.

9. In particle separation, the more conductive is the lio wever, it is not essential to the successful practice of particle, the higher is the separation efficiency, and also this invention that a coales. ting electrode, where em-65 the lower is the required electrical load for a given ploved, be grounded.

separation etTiciency.

He results of extensive study and developmental

10. De smaller is the applied electncal load, the wo-k have shown that substantially complete separa-greater is the required residence time fer the particles 868 349

y-1 4,066,526 and/or molecular species. Also, the greater the concen-liquid can be transformed into particulate form, intro-tra' ion of the particles and/or molecular species, the duced in that form into the apparatus with said fluid as greater is the required electrical load wluch must be the continuous phase, and readily separated in the same applied.

apparatus after the contacting operation. Absorption or Du

11. The flow conditions inside the apparatus can af-5 adsorption processes carried out in apparatus con-Q fect the eflienney with which the rejected matenal is structed and operated in accordance with the present collected and withdrawn.

invention can be greatly enhanced by virtue of the

2. The particles to be separated tend to clog the greater case of separation of the particulate matter.

separsting ele: trode when the applied electrical load is In order to illustrate specifically the practice and the insuflicient.

10 benefits of the present invention, the experimental appa-To summarize, the present invention has the follow-ratus referred to and described in detail in connection l

Ig ing several u:ique and desirable features, namely:(1)it with FIGS. I and 2 of this application were utilized in provides saba.tantially complete and economical separa-a number of experimental separation runs conducted in tion of particitlate matter and ionizable molecular spe-accordance with the invention. The results of some u

cies from s liquid or gaseous medium; (2) it perniits of 15 typiegl runs are given in Tables I and II, the former Pr 1 uly continuc us operation; (3) the apparatus and opera-reporting the results of runs involving the separation of tion r re extremely simple; (4) the apparatus is compact particulate matter and the latter containing the results

~

ar.d portable; snd (5) the method is flex 2ble and applica-of runs involving thd separation of molecular species.

ble to a wide range of operating conditions. Here are ne apparatus used for each run is indicated by refer-cther t:enefits and advantages which will be apparent to 20 ence to the figure in which it is illustrated, and in con-these skilled in the art. Because of these unique and nection with which it is described in detail.

cesirule f:stures, this inven* ion is t.seful in the purtfica-In each of the runs reported in Table I, at least ninety a

g I

i.nn, recover!, removal, sampling, analysis, separation, percent (90%) by weight of the dispersed particulate a

fr,ctionation. concentration, dilutien and the like, of all matter would pass through a standard 400. mesh Tyler se sens of partic ulate matter (solid or liquid), and of any 25 screen. For the runs in Table II, involving the separa-5 molecular sprcies which are ionizable-tion of molecular species, the splitting ratio in which the cc In accordance with the practice of the present mven-fluid medium of the feed solution is divided between the t.on, there are a number of alternative and desirable two ef11uents is t:1. The separation efficiency was deter-ways by which par iculate matter and/or molecular mined to be the difference between the concentration of species can be readily separated from a fluid medium in 30 the dispersed matter in the charge stream and the con-whien they are contained originally. Examples are: (1) centration of dispersed matter in the effluent stream y

the fikd med um containing the dispersed matter can be containing the reduced concentrat.on of dispersed mat-C brought into centact with, and then allowed to flow ter, expressed as a percentage of the concentration of throrgh, a separating electrode provided by this inven-dispersed matter in the charge stream. By a material t:on, but wit sout usmg a collecting electrode; (2) a 35 balance, the concentration of dispersed matter in the colle.:tmg electrode may be used in conjunction with effluent stream containing the increased concentration the 9Taratme electrode; (3) for fractionation purposes, of dispersed matter can readily be computed. Air was II a mixture of the difTerent types of materials to be frac-used as the fluid medium in each of the experimental l

tionated may be dispersed into a fluid medium first, and runs of Tables I tad II. The operating temperature in all Cy tFen fractionated as described herein (in this way, parti-40 runs was room temperature. For all of the runs reported b

c!c sire and/or mass spectra of dispersed matter can be in Table I, the operating pressure was I atmosphere.

8 determined); 4) the separating electrode may be moved For the runs involving separation of CI, shown in through a sti: nary body of fluid medium containing the Table II, an operating pressure of 10 p.s.i.a. was used.

di3ps tsed matter to be separated, said matter being se-All other runs reported in Table II were conducted at I

lectively repulsed and moved by the moving electrode 45 an operating pressure of I atmosphere. In all cases, the 5

from one end of the fluid bulk toward the other end;(5) current flow through the apparatus was less than 2 the cyclone efTect may be utilized to facilitate the re-milliamperes.

C moval of 'he collected matter from the collecting elec-TABM I e

trede: (6) a movmg collectmg electrode may be used to f atihtate the withdrawal of the collected matter by 50

-SEPARATION OF PARTICUt ATE MATTER

^7 n"M'** '*d s,,,,anoe C

designing the collecting electrode in the fortn of a rotat-mp,,w ing drum, belt, or the like; (7) a pair of separating elec-pamculane (Ret.

voltase la Out Emciency trodes, as contemplated by this invention, may be used Maner Fig )

(K.V.)

ism /m') (sm/m )

(%)

s 8

I in the same a,paratus to generate separately both nega-Alununum 7

-s a3730 comt 99 79 tase artd pos tive corona discharges for simultaneous 55 j

R action s

p waration from the fluid of both electronegative and Emmuos 2

-:o 03110 0.0c01 0 9s 2

electropoutise molecules or positive ions and radicals, j

gy y th y

as rnay be novious; (8) several separating electrodes oude I

- 25 0 4560 0 0D4 99 0s may tu place s in the same apparatus, as shown in FIG.

l

-J ojj g g98 3, for the fractionation of a mixture of various types of 60 cardo.

1

- 40 04560 0 0005 99 99 di:p"rsed matter; (9) the dispersed matter to be sepa-maca

- 55 a4seo como 100 ra:cd fromia ' fluid medium can be charged or ionized j

j (jy j*oo$

,N 8

uvng a con"entional discharging electrode prior to portland i

- 50 0456a c axis 99 99 cenuct with the separating electrode provided by this Cemens I

- 55 a43w acms nw f

nvention- (1-)) for a process in which it is desired to 65 Ny$

i

_ 45 a.456o o.00:3 99 7o ec ntact a solid with a liquid or gaseous fluid, or a liquid 1

- 55 0456o oom6 99 99 vth i ga.ecos fluid, such as, for example, for the pur-M*

j "l% $*nd M

I a

pose of mass transfer or chemical esction, the solid or 2

75 o3730 0.a)t0 99 74 868 350

~.mgumm I

i 4,066,526 i

14 13 rejected matenal. As in the conventional electrostatic TADLE l-contmued precipitator, a conditioning agent such as water vapor

__ SEPARATION OF PARTIC1; LATE MATTER can be used to improve the charging and collectmg

^7, o pe yyn d _ sepnanon characteristics of the particulate matter to be separated.

concen A liquid such as water also can be used to scrub the c

og Panewage (Ret.

voluse la out Emciency 5 particulate matter in the apparatus as is done in the 8

3 Mmer Fig.)

%v.)

(sm/m ) (sm/m )

(%)

2

- 10 amo aoots 99 68 conventional wet electrostatic precipitator.

j

j EN When the apparatus is used as a contacter for mass i

transfer operations, such as for absorption or adsorp-2

-40 0 3730 0.0000 100.

-g oj7y[$

10 tion, the liquid or solid should be introduced into the 2

apparatus in the particulate form, as may be obvious. As Iron onuse

- 30 14560 0.00:5 99 67 Powder

- 43 04seo 0.0002 99 95 a chemical reactor, any solid or liquid reactants must SNE $$

also be introduced in the particulate form for better 2

40 o.373o 0.0010 99.73 contacting and easy separation within the same appara-Zia: Onde

- 25 0.4560 opo25 99.44 15 tus.

Powder 1

- 40 0.4560 aooto 99.73 It is apparent that the recycling of the fluid stream g

- 45 a4560 aooc7 99.85 j

j (y$ {$

EE being treated can also be practiced in the apparatus to increase the final separation efficiency. In the alterna-tive, several units of the apparatus may be connected in 20 parallel and/or series in order to increase the capacity TABLE II and/or the separation efilCiency.

SEPARATION OF MOLECULAR SPECtEs It should be undentood that the charging, and there-concentranon or Melee.

Vols.

Molecular species sepersace fore the discharging, of said separating eles..w pro-uhr Apparatus age in out E5ciency vided by this invention can be efTected in various ways 3gggg gg, g

g Spmes (Re( Fig.)

%V.)

(p-p.m.)

(p.Put)

(%)

l l$

!E S!

$o'i pie, the separating electrode can be charged directly by CU connecting it to a power source, or charged inductively cct.

I

- 25 500 220 5425 j

j 7$

by placing it very close to a separate discharging elec-I" trode. The resultant corona discharge can be effected so, s

-is soo 330 33.65 j

j Q

y y

30 by any one or a combination of the following several well.known mechanisms: (1) cold emission; (2) hot

-ss 500 54 s9.14

g 2g y

y emission; (3) ion bombardment at the electrode surface, NO I

and the like.

ci, 1

- 20 soo 292 41.43 The charging of particulate matter, and the ionization

- 43 sao 125 75.06 35 of molecules, also can be carried out through various 8

- 35 30 Il 38

'33 mechanisms, for exangf (1) conductive induction in addition to those molecular species listed in Table charging; (2) contact electrification; (3) space charging; II. many other molecular species, including inorganic (4) electron attachme.it; (5) electron impact; (6) photo-ionization at electrode surface; (7) photo-ionization in compounds such as HF, H S, NO, NO3, SF., and the 2

2 like, organic compounds including various hydrocar-40 space; (8) ionization accompanied by decomposition; and other forms of chemical changes.

bons, alcohols and the like, and various radicals dissoc2-ated from these molecules, have been separated success-It is important that excessive space charging, back corona and other abnormal charging phenomena be

felly, Other experimental runs have been made using appa-peevented in the apparatus through prompt removal of

~

ratus (including a separating electrode) of varymg de-45 the charged and/or ionized rejected material from the sign but within the scope of this invention, and with

' apparatus. The " leak coeflicient" of the separating elec-v1riations in the operating conditions including electri-trode may be afTected by any one or a combination of cal loads. In all such cases, substantially similar benefi-the operating variables discussed above, as may be obvi-c al results were obtained.

ous.

It is apparent from the above illustrations and discus-50 It should be understood that this inveuion applies to sion that charged or chargeable particulate matter and the separation of all charged (and chargeable) particu-ionized or ionizable molecular species can be readily late matters, solid and/or liquid, and/or ions and ioniz-able molecules, radicals and atoms, from a fluid medium separated from a fluid medium in which they are con-in which they are contained, by passing said fluid me-tamed, by passing said fluid medium through a filter like separating electrode generating corona discharge in 55 dium through an electrode which is made in the form of a:cordance with the practice of this invention. He a filter and which is electrically charged in the same material of construction and the design of said separat-polanty as that of the charged particulate matter and/or ing electrode, the over-all design of the apparatus, the ionized molecular species, and by use of the electro-static repulsive force acting between said electrode and applied electrical load and voltage wave form may be varied according to the material to be separated and the eo said charged particulate matter and/or said iontzed eperational conditions. De apparatus provided by this mo!elcular species as the driving force for separation.

mvention can also be used as a contacter, to effect Therefore a densely. formed corona discharge over the contact between a fluid and a particulate matter, and the entire surface of said filter-like separating electrode, and f'uid and particulate matter can subsequently be sepa-the resultant strong electrostatic repulsive force be-65 tween said electrode and said charged particulate mat-rsted.

It is obvious, also, that mechanical means such as ter or ionized molecular species to be separated. are the keys to the separationgnjrti gd provijfqd by this inven-ubrators, scrapers, sonic devices, or the like, may be t

tion.

U00 JJl t aced in the apparatus to facilitate the removal of the l

4,066,526 The invention laimed is:

4. Method according to claim 1, wherein said corona

1. Method for separating dispersed matter consisting discharge is generated by a series of very short high esser.t ally of electrostatically-charged finely-divided v It*8e Pulses applied to said separating electrode.

5. Method for separating dispersed matter consisting particles frcim a fluid medium containing same, said 5 essentially of ionized molecular species from a fluid nethod compnsmg:

medium containing same, said method c' mprising:

A. Continuously introducing said fluid medium con-A. Continuously introducing said fl-medium con-taimng the dispersed matter into a non-collecting taining the dispersed matter into e '

!!ccting separation chamber ia the zone adjacent a first side separation chamber in the zone adjace' a first side of a separatirig electrode which divides said cham.10 of a separating electrode which divides said cham-ber :nto two zones and which is pervious to the ber into two zones and which is pervious to the passage of said fluid and dispersed matter; passage of uid fluid and dispersed matter; B. Continuously subjecting said introduced fluid me-B. Cor.tmuously subjecting said introduced fluid me*

dium containing dispersed matter to the field of a dium containing dispersed matter to the field of a 15 dense and uniformly-distnbuted corona discharge dense and uriformly-distributed corona dischar,ge occurring from said separating elec* rode, said sepa-s :

occurring frem said separating electrode, said sepa.

rating electrode containing an electrostatic charge l

rating ele:trede contaimng an electrostatic charge of the same polarity.as that of the charge on said f

of tre sarne polarity as that of the charge on said m lecular species and of a magnitude sufficient O

substanuaHy to repel sam mle* spedes,

lr.ely-divided particles and of a magmtude sufli-whereby said molecular species are selectively cient substan' sally to repel said finely-divided parti-repelled from said separating electrode; el-s. whereb/ said finely-divided particles are se-C. Continuously passing through said separating elec.

'ectively repciled from said separating electrode; trode and withdrawing from the zone adjacent the C. Contmucusly passing through said separating elec. 25 reverse side of said separating electrode fluid me-trode and wvhdrawing from the zone adjacent the dium containing a reduced concentration of said reverse side of said separating electrode fluid me, miecular species; and dium :ontai:ing a reduced concentration of said D. Continuously withdrawing from the zone adjacent said first of said separating electrode a fluid me-tinelv-div:ded particles; and 30 dium containing an increased concentration of said D. Cortinuc usly withdrawing from the zone adj.acent molecular species.

Nud first side of said separating electrode a fluid

6. Method according to claim 5, wherein said dis-medium containing an increased concentration of persed matter to be separated from said fluid medium is tmd finely-divided partic!cs.

charged prior to being subjected to the field of said

2. Method according to claim 1, wherein said dis. 35 corona discharge.

,crsed matter to be separated from said fluid medium is

7. Method according to claim 5, wherein said dis-i uharr.ed prior to being subjected to the field of said persed matter is charged by being subjected to the field 2

of said corona discharge.

crona d:schange.

8. Method according to claim 5, wherein said corona

3. Method according to claim 1, wherein said dis 40 discharge is generated by a series of very short high

.ersed matter :s castged by being subjected to the field voltage pulses applied to said separating electrode.

af said corona dis:harge.

45 50 55 60 I

E 65 868 352

U.S. Patent Jan. 3,1978 Sheet I of 3 4,066,526 25

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ELECTROSTATIC CHARGE GENERATOR 22 x lic

-+fr 12 f

s T

s

'gS'////.07/j

,26 S\\a 20 s

e lia v

g N

27

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1 >x A

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20 - _

3

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868 353

a U.S. Patent Jan. 3,1978 Sheet 2 of 3 4,066,526 55

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53 ELECTROSTATIC

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45 CHARGE

/

GENERATOR

/

/

l 60t ';

42 53, Sla 4/

[

41b \\ / [41a

)

56 -

45 -:d?_lM

s_s f l

/

A x

57 50 /

E 4

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=-

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k

51 5

4

/D 51b 52 60b F

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65 40,60 E!

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v F'iq. 2 868 354

U.S. Patent Jan. 3,1978 Sheet 3 of 3 4,066,526 80 j

79 ELECTROSTATIC

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CHARGE GENERATOR 75

[.

900 96 s

.f 86 OI Sfa.d 91 81a Slb gS

~

ll<

7;1 87 82 92a 2

92b 1 356 :

72 -~

'90a 90a w 88

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Fiq.3 868 355