US3402119A - Unitary corona reactor including opposed planar non-vitric dielectric walls - Google Patents

Description

p 7, 1968 w. R. BROWNE ETAL 3,402,119

UNITARY CORONA REACTOR INCLUDING OPPOSED PLANAR NON-VITRIC DIELECTRIC WALLS Filed May 10, 1965 2 Sheets-Sheet 1 [)7 ven at 0/29. MW/m RBPO wn 6, John Z No Namamz by 14m 777a)" A C t orney UNITARY coRoNA RisAcToR INCLUDING OPPOSED PLANAR NoN-vr'rRrc DIELEC- TRIC WALLS of corona reactors were constructed from glassware. In considering operations beyond the laboratory level, however, such reactors present serious problems stemming from the propensity toward breakage of glassware, includ- William R. Browne, Scotia, and John E. McNamara, 5 Safety hazards, to Personnel g q p ent, the re- Schenectady, N.Y., assignors to General Electric Comflulrfiirflent of Speclal Care handhbg and mountlng, the Daily, a corporation f N York inability of glassware to reliably withstand over-all high Filed May 10, 1965, Ser. No. 454,627 temperatures or localized elevated temperature, the risk 3 Claims. (Cl. 204-312) of placing a process off-stream, etc.

. I industrial environments, mo rugged types f corona reactors have been proposed. Such reactors typi- ABSTRACT OF THE DISCLO RE cally include a housing forming a chamber or plenum A comma reactor is disclosed which is formed as a to confine the gaseous media in which the corona is to be single unitary structure by a i l molding operation propagated, electrodes mounted w1thin the housing, units f o a moldable, dielectric material Such as a ceramic to mount electrodes 1n the desired relation to the housing or Synthetic resin which is chemically inert with respect and to each other, d1electr1c barriers either attached to to the reactant to be treated therein. The reaction chamthe elfictl'odbs p b tbefebetWeel} y parate ber comprises inlet and outlet means with a reaction zone moubtmgs, and, 111 dynamic reactors, gl s t0 dlrect therebetween, the reaction zone being defined by a pair fiowlng reacbaflts tbfqllgb the C na. Wh11e such corona of ll l b i ll rectangular ll portions haw reactors avoid the dlstadvantages encountered In using ing smooth interior face portions spaced a constant dislaboratory glassware, Such feactofs heretbfore produced tame apart h spacing di i being much smaller have been relatively expenslve due to then unduly comthan any lateral dimension of the rectangular wall por- P and cumbersome structural f orms.

tion. The outer surfaces of the rectangular wall portions P 15 an l l of our lbventloll t0 PTOVlde 511111916,

have electrode supporting portions which are substantially 2 un1ta1:y economlcal'ly fflbl'lcated' I HH r ac Ol'.

parallel to each other and to the corresponding inner sur- It 13 another to Provlde a corona r a t r of face of the rectangular wall portions. l'llgge'd I1- tI is an additional ob ect to provide a corona reactor capable of operating at elevated temperatures with mini- Our invention relates to a unitary corona reactor. ma1r1 Sk of damage- When two bare electrodes separated by a gaseous It 15 a further b l of 0111 lnvellbob p media are subjected to a potential difference, an electric Porona reflctor Wblcb can be formed y a slmple moldarc may be generated between the electrodes by ionizamg opbratlontion of the gas. An electric arc is a high current, low These and b? l f 0f 9 n l n are accomvoltage electrical phenomenon visually discernible by its 5 p b y PTOVldlIlg a dlelectflc Corona reactor boublng limited areal extent and sharp boundaries. If the preshavlng first and pp Planar, substabtlany sure, and hence density, of the gaseous media lying be- Parallel W811 port1ons a fi st and e ond electrodes tween the electrodes is reduced well below atmospheric mounted bxteflol'ly 9 581d bollslbg and adlacbnt Sald first pressure, a potential difference applied to the electrodes and secgmd a port1ons, respectlvelywill produce a glow discharge. A glow discharge is char- 40 our lllvelltlfm yb better. b fl y reference acterized by a soft diffused appearance extending over a t e llowlng deta led description considered in consubstantial area and lacking distinct boundaries. Such dis- Junctlon Wltb f dfawlngs, 111 Wh lbb charge is formed by electrically energizing gaseous par- FIGURE 1 15 a from elevatlon, P y 1n F ticles by direct contact with the electrodes. The low presa Corona feabtbf l 1 1 sure, however, prevents the formation of a gaseous ionic FIGURE 2 15 a slde P y lIl Sectlon, of t e conducting bridge between the electrodes which would Corona reactor b FIGURE tha are; first? of ird and com letel distinct type of electrical dis- 1 e "f ch a rg e is termed a c o rona discharge. When two electrodes FIGURE 4 18 R sldfi elevatlolhfpaftly lglrj s a 0f the are separated by a gaseous media and also by one or modlfiedform 0f corona t r FIGU more dielectric barriers, the application of an alternating Refefrlng t0 FIGURES 1 and a Cor a r actor 1 current to the electrodes will capacitively excite the gase- 15 Connected Y boupllng collar 2 t0 Inlet b dl lthll ous media to produce a corona discharge therein. Such d by a upllng c01lar 4 to an outlet CO I1dl1]11t 5 T 2 type discharge differs from an electric arc in being a high C na reactor is compr sed of a d electric1 ousing voltage, low current phenomenon. Further, corona dlsformed of an 3 fabflcated, r-v trle 1 tlrlc Inacharge, while visually similar to glow discharge, differs terral such as, for example, a synthetic resin. The ous mg markedly therefrom in that corona discharge propagaincludes a first wall portion 7 which 18 of uniform thicktion does not require direct contact between the elecness Directly opposite and spaced from the first wall trodes and the gaseous media or reduced pressures to portion 1s a similar substantially parallel wall portion avoid arcing. Additionally, unlike an electric are or a glow 8. Each of first and second wall port ons 7 and 8 merge discharge, a corona discharge can be generated only by smoothly into surrounding wall portions 9 and 10, rean electrical energy source of alternating current. spectively, of greater thickness than the wall portions Various forms of apparatus have been constructed 7 and 8. In the area where the wall port1ons 7 and 8 merge for treating gases and liquids in the presence of a corona into the surrounding wall port1ons 9 and 10, respectively, discharge. The earliest and still most widely used forms an arcuate surface 11 is formed on the exterior surface of the housing. The surrounding wall portions 9 and 10 are joined together by integrally formed side walls 12 and 13.

Mounted adjacent the wall portions 7 and 8 are electrodes 14 and 15, respectively. Electrode 14 is provided with a planar face portion 16 conforming to the exterior surface of the wall portion 7 and an arcuate perimeter portion 17 conforming to the arcuate surface 11. Electrode is similarly provided with a planar face portion 18 and an arcuate perimeter portion 19. The electrode may be formed as separate metallic elements pressed against or adhered to the housing or may be formed as a conductive coating on the exterior of the housing such as a conductive paint, electrodeposited metal, etc.

It is noted that the electrode 14 and the wall portions 7 and 9 cooperate to form an electrode assembly including an electrode and dielectric barrier. The electrode 15 and the wall portions 8 and 10 cooperate to form a similar electrode assembly. The sidewalls 12 and 13 act as means for joining electrode assemblies in spaced relation through the dielectric barriers.

The wall portions 9 and 10 and side walls 12 and 13 converge at each end of the housing to form inlet and outlet necks 20 and 21. The space between the walls 12 and 13 and wall portions 7 and 8 forms a chamber 22 in which a corona may be propagated. An inlet conduit 23 may be connected to conduit 3 to introduce a material to be treated into the corona within the chamber 22. Material is exhausted from the chamber 22 through neck 21 and outlet conduit 5 connected to conduit 24. A portion of the material exhausted from the corona reactor may be recirculated by means of conduit 25 extending from outlet conduit 5 to inlet conduit 3 and having a pump means such as 26 connected therein.

A potential is supplied to the electrodes from a source of alternating current 27. The alternating current source is connected to a tuning circuit schematically shown at 28. The tuning circuit in its three simplest forms may be comprised of a variable capacitance and inductance in shunt, a variable capacitance in shunt and an inductance in series, or a variable capacitance in series and an inductance in shunt. Other tuning circuits are of course known and utilizable. Electrical leads 29 and 30 extend from the tuning circuit to electrodes 14 and 15, respectively.

In operation, the corona reactor 1 is supplied with a material to be treated through conduits 23 and 3. Subsequent to purging the system, an electrical potential is applied across the electrodes 14 and 15 through leads 29 and 30. A corona discharge is formed within the chamber 22 between the electrodes and in intimate contact with the material to be treated. The arcuate perimeter portions 17 and 19 of the electrodes 14 and 15 provide for a rapid decay in electric field strength beyond the edges of the electrodes thereby preventing power losses through stray edge currents not contributing to the propagation of the corona discharge. The tuning circuit 28 provides for electrical load circuit power factor correction so that the electrical energy source 27 secs only the resistive load represented by the corona power.

The material undergoing treatment exhausts from the corona reactor through neck 21 and conduit 5. The material is subsequently transported to the next process phase through conduit 24. If desired, a portion of the material treated may be recirculated through conduit 25 through operation of pump means 26.

FIGURES 3 and 4 illustrate a second exemplary form of corona reactor 100. The reactor includes a unitary molded ceramic housing 101. The housing terminates at its upper extremity in a flange 102. The lower end of the housing is shown provided with a port 110.

A tapered fitting 103 is shown connected to the upper end of the corona reactor having a flange 104 at one end and a ring coupling 105 at the other end. An annular sealing ring 106 is mounted between flanges 102 and 104. The flanges are pressed together to compress the sealing ring by means of clamping rings 107 and 108 joined by tie bolt assemblies 109. The ring coupling connects the tapered fitting 103 to afluid conduit.

A fluid conduit 111 is shown sealed against the housing within port by an O-ring seal 112. The O-ring seal is held in position on the conduit by shoulders 113 and 114. The tapered fitting 103, outlet conduit 111, and attendant elements form no part of the corona reactor 100 but are merely exemplary of the type of connection means which may be employed in combination with the corona reactor.

The housing 101 of the reactor includes spaced, opposed, substantially parallel front and rear wall portions 115 and 116 which are joined at their edges by side wall portions 117 and 118. Electrodes 119 and 120 are mounted adjacent the wall portions 115 and 116, respectively. The electrode 120 is connected to ground by lead 121. The electrode 119 is connected to a tuning circuit 122 schematically shown by a lead 123. The tuning circuit is connected to ground by lead 124 and to a source of alternating current 125.

The corona reactor 100 may be operated similarly to the corona reactor 1. While reactor operation has been disclosed in terms of continuous circulation of reactants, it is contemplated that the reactors may be used to treat fluids statically contained therein. In certain instances, it may be desired to treat a fluid contained in a dielectric package without removing the fluid from the package. The corona reactor 100 is particularly amenable to such use. In certain instances, it may be desired to introduce a solid substrate into the corona reactor to be coated by fluid undergoing corona treatment. Also, it may be desired to continuously pass a substrate through the reactor for treatment or coating within the corona zone. In such instance, the configuration of the inlet and outlet openings of the housing may be formed to correspond to that of the substrate. As previously indicated, the inlet and outlet couplings of the corona reactor may be chosen from a wide variety of known coupling structures. In certain applications, it may be desired to purge the reactor with a fluid other than the fluid to be treated, such as helium, argon, nitrogen, etc. Provision for the circulation of a purging fluid may be made by providing suitable connections to the inlet and outlet conduits or by providing additional inlet and outlet ports in the housing. While the reactor electrodes are shown mounted exterior of the housing, it is of course contemplated that the electrodes may be encased within the housing according to the teaching of our abandoned, previously filed application Ser. No. 409,199, filed Nov. 5, 1964.

Numerous additional modifications will be readily suggested to those skilled in the art. For this reason, it is intended that the scope of our invention be determined by reference to the following claims.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A unitary corona rector comprising a hollow housing integrally cast from a non-vitric dielectric material which is chemically and physically inert with respect to the environmental conditions of the reaction, said housing comprising inlet means for the reactant, a reaction chamber, and outlet means for the reaction product, said reaction chamber comprising a pair of opposed, spaced, substantially parallel, planar wall portions, said wall portions each having opposed electrode supports formed by substantially rectangular recesses in their outer surfaces, each of said recesses being composed of a planar recessed surface having an arcuate perimeter portion curving outwardly of said planar recessed surface, said planar recessed sufaces being substantially parallel to each other and to the inner surfaces of said planar wall portions, and electrodes comprising electrically conductive layers coating the surfaces of said recessed portions including said arcuate perimeter portions.

2. The corona reactor as recited in claim 1 wherein the space between asid wall portions defined by said References Cited oposed electrodes comprises a substantially rectangular t'o zon wherein said space has a transverse d' UNITED STATES PATENTS reac 1 n e unen- 2,327,457 8/1943 Raisch 204317 slog substantially smaller than any lateral dimenslon of 5 2,364,940 12/1944 Bias 20 164 Sal mac Zone- 2,864,755 12/1958 Rothacker 204-165 3. The corona reactor as recited 1n claim 1 wherein 3,320,151 5/1967 Tepe et a1 204 176 said electrically conductive layers comprise coatings adherently deposited on the surfaces of said recesses. ROBERT K. MIHALEK, Primary Examiner.

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