WO2002081369A1

WO2002081369A1 - Ozone generator

Info

Publication number: WO2002081369A1
Application number: PCT/US2000/025992
Authority: WO
Inventors: Mark D. Goodley
Original assignee: Agtech International, Inc.
Priority date: 2000-04-02
Filing date: 2000-04-02
Publication date: 2002-10-17

Abstract

An ozone generator (10A) in which each dielectric (30) has a plurality of lines of corona discharges on each side; turbulent flow increases the ozone-forming dwell time within the generator; and back pressure, resulting from the turbulent flow, increases the pressure concentration of gas exposed to the coronas. The generator comprises a plurality of ozone generating cells comprising interleaved electrodes and dielectrics having passageways therebetween for receiving gas containing oxygen. In each ozone generating cell, corrugated electrodes (20, 40) have mirrored crests equally spaced from a dielectric so as to form uniform gaps at the crests through which the received gas must flow.

Description

OZONE GENERATOR FIELD OP THE INVENTION

The invention is an ozone generator of the stack-type plate design employing interleaved electrodes and dielectrics, and more specifically provides for turbulent oxygen flow and more controlled exposure of the entering oxygen to corona discharge. BACKGROUND OF THE INVENTION

Ozone has increasing importance as a disinfectant. Ozone (0₃) , an allotropic form of oxygen, is a powerful oxidant. Ozone effectively kills bacteria by breaking up their molecular structure, inhibits fungal . growth, and inactivates many viruses, cysts, and spores. In addition, soaps, oils, and chlora ines can be rendered environmentally safe by ozone treatment. Ozone combines with water to form hydroxyl radicals and peroxide, thus sterilizing the water. Because ozone is unstable, the ozone decomposes to oxygen leaving no residues to further eliminate. Ozone has a half-life of about 22 minutes in water at ambient temperatures. Consequently, for most cleaning/disinfecting operations, the cleaning residue after a short period of time contains only dead biological matter and water and, typically, requires no special disposal.

In typical, conventional ozone generators of the corona discharge type, a very low percentage of the entering oxygen molecules actually encounter the corona discharge^' so as to form ozone. The corona is produced only on one side of a dielectric. The ozone concentration in the discharged gas is low and the efficiency of the generator^' is low, particularly with regard to their size.' Consequently, most ozone generators are used in stationary industrial applications because of their large size and energy requirements. It is particularly desirable in mobile cleaning and disinfecting apparatus using ozone generators that the ozone generator be of compact size and as efficient as possible.- SUMMARY OF THE INVENTION T.his_.-invention— s -a ozone—genera-tor-,— and- a preferred embodiment comprises an enclosure including"'an entry chamber for receiving gas, such as air from a dryer or from an o ygen concentrator or oxygen, such as from a liquid oxygen source, a plurality of ozone generating cells comprising interleaved electrodes and dielectrics having passageways therebetween for receiving gas from the entry chamber and converting the oxygen therein to ozone, an alternating voltage generator connected to the electrodes so as to create corona discharges between them and an adjacent dielectric, and an exit chamber 85 at the other end 84 of enclosure for receiving the gas and ozone.

An ozone generating cell includes a first electrode, a second electrode, and a first dielectric. The first electrode includes a -top face. The first dielectric includes- a botrom face opposed to the top face of the first electrode and separated therefrom so as to form a first passageway, and a top face. The second electrode includes a bottom face opposed to the top face of the first dielectric and separated therefrom so as to form a second passageway. The received gas flows through the passageways. The top face of the first electrode includes a plurality of crests and troughs relative to the bottom face of the dielectric and traversing the flow of received gas through the first passageway. The bottom face of the second electrode includes a plurality of crests and troughs relative to the top face of the dielectric and mirroring said crests and troughs of the top face of the first electrode. The passageways between the crests and the dielectric have a uniform gap.

Each dielectric has a plurality of lines of corona discharges on each side. The. received gas must flow through substantially a continuous curtain of corona discharge at each crest gap. The turbulent flow increases the ozone-forming dwell time within the generator.. The back pressure resulting from the turbulent flow increases the pressure concentration of gas exposed to the coronas.

BRIEF DESCRIPTION OF THE DRAWINGS .Figure- ₁ -is- a--diagram -of an ozone-generating device including a preferred em_bodiment _of the ozone generator of the invention.__

Figure 2 is a^"partial perspective view of an ozone generating cell of the preferred embodiment of Figure 1. Figure ₃ is a partial vertical cross-sectional view of the ozone generator of Figure 1.

Figure 4 is a partial vertical cross-sectional view of a first alternate embodiment.

Figure 5 is a partial vertical cross-sectional view of second alternate embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 is a diagram of an ozone generating device ⁸⁰ including an enclosure 81 containing a first preferred embodiment -1₀A of the ozone generator 10 of the invention. Gas, including oxygen, such as air ₉8 from a dryer or from an oxygen concentrator, is received by. propelling means, such as pump P, an^d propelled into an entry manifold or chamber 83 at one end 82 of enclosure ⁸1. Entering air ₉8 flows through ozone generator 10A, where the oxygen gas is converted to ozone. The gas including ozone 99 enters exit manifold or chamber 85 at the other end 84 of enclosure 81 an^d exits through exit orifice 87.

_Ozone generator ₁₀A includes a plurality of ozone generating cells including a plurality of high potential electrodes,^, such as first electrodes 2₀, connected to an alternating high voltage source ₉5, a plurality of earth or ground electro^des, such as secon_d electro_des 4₀, connected to ground and a plurality of _dielectrics ₃₀, a dielectric 30 being disposed between adjacent first electrodes 2₀ and second electrodes 40. Electrodes 20,40 and _dielectrics ₃₀ are- all mounted interleaved in spaced relationship with their faces opposed. In this manner, first electro^des ²⁰ and second electrodes ₄₀ are- electrically connected such that alternating high voltage electrical potentials exist between them. The walls of enclosure 81 are sometimes used as the two outer^¬ most second electrodes -40. Enclosure 81 is coole^d in a manner known in the art . Figure 2 -shows a partial perspective view of a preferred embodiment of an ozone generating cell of the ozone generator 10A of Figure 1. Figure 3 being a partial vertical cross-sectional view of Figure l. Ozone generator 10A generally includes a first electrode 20; a first dielectric 30 and a second electrode 40. First electrode 20 includes a first end 21, a second end 22, an entry side 23, an exit side 24, bottom face 25, and a top face 26. Preferably, first electrode 20 is a corrugated plate such that its top and bottom faces 26,25 include a plurality of crests and troughs traversing between its first and second ends 21,22. One end or both ends 21,22 are supported, such as by enclosure 81 and/or by nonconducting spacers.

First dielectric 30 includes a first end 31, a second end 32, first side 33, a second side 34, a bottom face 35, and a top face 36. Bottom face 35 is opposed to top face 26 of first electrode 20 and separated therefrom so as to form a passageway 90, such as first passageway 90A, for flow of air 98. Dielectric 30 may be made of suitable dielectric materials, such as glass or ceramic, with ceramic being preferred. Ceramic is preferred because it well withstands the temperatures produced, yet does not readily break if subjected to shock or if it is rapidly cooled, as happens in some usage environments of generator 10A.

Second electrode 40 is a corrugated plate and includes a first end 41, a second end 42, an entry side 43, an exit side 44, a bottom face 45, and a top face 46. Bottom face 45 is opposed to top face 36 of first dielectric 30 and- separated therefrom so as to form a second passageway 90B. Electrodes 20, 40 may be made out of many suitable conductive materials as are well-known in the art, such as aluminum or stainless steel, with stainless steel being preferred because of its greater resistance to corrosion.

Received oxygen bearing gas ^'98 flows through first passageway

90A from entry side 23 of first electrode 20 to exit side 24 of first electrode. Received oxygen bearing gas 98 also flows through second passageway 90B from entry side 43 of second electrode 40 to exit side 44-- of second electrode 40.

Top face 26 of first electrode 20 includes a plurality of crests 26C and troughs traversing the flow of received gas 98 through first passageway 90A. Bottom face 45 of second electrode 40 includes a plurality of crests 45C and troughs mirroring the crests and troughs of top face 26 of first electrode 20. The gap G between each crest 26C, 45C and dielectric 30 is uniform.

Fig. 3 shows a plurality of first electrodes 20, dielectrics 30 and second electrodes 40 mounted in accordance with the preferred embodiment of the invention. Entry oxygen-bearing gas 98 flows through passageways 90A-90F. The crests and troughs of adjacent electrodes 20,40 mirror those of the adjacent electrodes thus varying the height of passageways 90 relative to dielectrics -30 with the height being a minimum at gap G between each crest and dielectric 30. Typical size of gap G is l-3mm. The resultant electric field strength varies from a maximum between mirrored crests to a minimum between mirrored troughs. Alternating voltage source 95 provides voltage to produce a discharge or corona between mirrored crests and interposed dielectric 30. The wave form for producing the corona discharge is essentially an alternating high- frequency square wave with a typical voltage range being alternating 4K-10K volts and typical frequency range being 10K-30K Hertz. Therefore, along the length of each gap G, each dielectric 30 has a series of discharge coronas almost continuously touching both bottom and top faces 35, 36 so as to form a curtain of corona. The voltage alternates at high frequency such that all entering gas 98 must pass through a fairly continuous curtain of corona at each gap G. In this manner, all of the oxygen molecules are exposed to corona for disassociating atomic oxygen. The wider areas of passageways 90 between the troughs and dielectrics 30 provide for turbulent flow of air 98 and provide dwell time for recombination of the disassociated oxygen atoms into ozone.

The turbulent flow increases the ozone-forming dwell time within the generator. ^• The - back pressure resulting from the turbulent flow increases the pressure concentration of gas exposed to the coronas.

Figure 4 is a partial vertical cross-sectional view of a first alternate embodiment ozone generator 10B, similar to generator 10A except between adjacent electrodes 20,40 there is only one passageway 90 because the interposed dielectric 30B has a face in contact with the face of one of the electrodes 20,40. Thus, there is only one passageway 90 for each dielectric 30B.

Figure 5 is a partial vertical cross-sectional view of a second alternate embodiment ozone generator 10C, similar to 10B except the electrodes of one set of electrodes, such as ground electrodes 40C, are flat and have both their faces in contact with the adjacent interposed dielectrics 30C.

From the foregoing description, it is seen that the present -invention provides an extremely compact and efficient ozone generator.

Although particular embodiments of the invention have been illustrated and described, various changes may be made in the form, composition, construction, and arrangement of the parts herein without sacrificing any of the advantages. Therefore, it is to be understood that all matter herein is to be interpreted as illustrative and not in any limiting sense, and it is intended to cover in the appended claims such modifications as come within the true spirit and scope of the invention.

Claims

I CLAIM :

1. An ozone generator including: an alternating voltage generator; and 2 an ozone generating cell for receiving gas including oxygen and for expelling gas including ozone; said ozone generating cell 4 comprising: a first electrode including: 6 a top face; a first dielectric including: 8 a bottom face opposed to said top face of said first electrode and separated therefrom so as to form a first passageway; 10 and a top face; 12 a second electrode including: a bottom face opposed to said top face of said first 4 dielectric and separated therefrom so as to form a second passageway; wherein 6 the received gas flows through said first passageway and through said second passageway; and wherein 8 said top face of said first electrode includes a plurality of crests and troughs relative to said bottom face of said dielectric; 0 said crests and troughs of said top face of said first electrode traversing the flow of received gas through said first passageway; 2 wherein said bottom face of said second electrode includes a plurality 4 of crests and troughs relative to said top face of said dielectric; said crests and troughs of said bottom face of said second 6 electrode mirroring said crests and troughs of said top face of said first electrode; and wherein 8 said alternating voltage generator is connected to said first electrode and to said second electrode for applying voltages 0 thereto so as to create corona discharges between said mirrored crests and said first dielectric.

2. The ozone generator of Claim 1 wherein said crests are uniformly spaced from said dielectric so as to form uniform gaps through which the received gas must flow.

3. The ozone generator of Claim 1 including a plurality of said cells.

4. The ozone generator of Claim 1 further including: an enclosure enclosing said cell.

5. The ozone generator of Claim 4 wherein said enclosure includes: an entry chamber for receiving the gas containing oxygen -before entry to said passageways.

6. The ozone generator of Claim 4 including a plurality of said cells.

7. An ozone generator including: an alternating voltage generator; and an ozone generating cell for receiving gas including oxygen and for expelling gas including ozone; said cell comprising: a first electrode including: a top face; a first dielectric including: a bottom face opposed to said top face of said first electrode and separated therefrom so as to form a first passageway; and a top face; a second electrode including: a bottom face in electrical contact with said top face of said first dielectric; wherein the received gas flows through said first passageway; and wherein said top face of said first electrode includes a plurality of crests and troughs relative to said bottom face of said first dielectric; said crests and troughs of said top face of said first electrode traversing the flow of received gas through said first passageway; wherein said bottom face of- said second electrode includes a plurality of crests and troughs mirroring said crests and troughs of said top face of said first electrode; and wherein said alternating voltage generator is" connected to said first electrode and to said second electrode for applying voltages thereto so as to create corona discharges between said crests of said first electrode and said first dielectric.

8. The ozone generator of Claim 7 wherein- said crests are -uniformly spaced from said dielectric so as to form uniform gaps through which the received gas must flow.

9. The ozone generator of Claim 7 including a plurality of said cells.

10. The ozone generator of Claim 7. further including: an enclosure enclosing said- cell.

11. The ozone generator of Claim 10 wherein said enclosure includes: an entry chamber for receiving the gas containing oxygen before entry to said passageways.

12. The ozone generator of Claim 11 including a plurality of said cells.

13. An ozone generator including: an alternating voltage generator; and an ozone generating cell for receiving gas including, oxygen and for expelling gas including ozone; said cell comprising: a first electrode including: a top face; a first dielectric including: a bottom face opposed to said top face of said first electrode and separated therefrom so as to form a first passageway; a top face; a second electrode including: a bottom face in electrical contact with said top face of said first dielectric; wherein the received gas flows through said first passageway; and wherein said top face of said first electrode includes a plurality of crests and troughs relative to said bottom face of said first dielectric; said crests and troughs of said top face of said first

-electrode traversing the flow of received gas through said first passageway; and wherein said alternating voltage generator is connected to said first electrode and to said second electrode for applying voltages thereto so as to create corona discharges between said crests of said first electrode and said first dielectric.

14. The ozone generator of Claim 13 wherein said crests are uniformly spaced from said dielectric so as to form uniform gaps through which the received gas must flow.

15. The ozone generator of Claim 13 including a plurality of said cells.

16. The ozone generator of Claim 13 further including: an enclosure enclosing said cell.

17. The ozone generator .of Claim 16 wherein said enclosure includes: an entry chamber for receiving the gas containing oxygen before entry to said passageways.

18. The ozone generator of Claim 17 including a plurality of said cells.