Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02327558 2001-O1-04
OZONE GENERATOR
FIELD OF THE INVENTION:
This invention is directed to an apparatus for
producing ozone and, in particular, an apparatus for
producing ozone using alternating current or pulsating direct
io current.
Background of the Invention
Ozone generators are known which employ corona
j5 discharge to produce ozone from oxygen by action or oxygen
atoms or. oxygen molecules. These generators employ a high
voltage alternating sinusoidal current operating at
frequencies of between about 60 and 5,000 Hz and voltages
frequently above 20 kilovolts. Such generators require high
zo voltage transformers which are difficult to construct and
insulate and which cause the generatcr to be very large i.~.
size.
During breakdown, oxygen or air in the gap becomes
25 partially ionized as several kilovolts of energy i=_ applied
to it, and milliampere to ampere currents result. Because c'
the required operating frequencies and voltages of most known
generators and the fragile nature of the dielectrics of the
reaction chamber, deterioration. o. the generators often
30 occurs, requiring maintenance arid repair. The construction
of known generators requires that the entire unit including
generator, transforme-- anc any associated electronics be
shipped offsite for repair and maintenance.
la
CA 02327558 2001-O1-04
To allow a better understanding of the prior art,
reference may be made to the following drawings of prior art
in which Figures 1 and 2, each show a prior art ozone
generator.
s
Referring to Figure 1, a plate generator i0 is
shown having a pair of metallic plate electrodes 12, 14 and a
layer of dielectric material 20 therebetween. Electrodes 12,
14 are separated to form a gap 18.
io
The ozone generator of Figure 2 employs a tubular
geometry and includes a first electrode 25 and a second,
larger diameter, eieccrode 26. Electrode 25 has a layer of
dielectric~material 27 disposed on the surface thereof and is
is positioned within electrode 26 to form a gap 28 therebetween.
In known generators, such as those shown in Figures
1 and 2, a high voltage current is applied to the electrodes
to produce a corona discharge in the gap. The discharge
zu produces ozone by ionization of oxygen which is presen~ in
the gap.
2
CA 02327558 2001-O1-04
Summar~of the Invention
It is an object of the present invention to provide an ozone generator. In
accordance with
an aspect of the invention there is provided an apparatus for producing ozone
from oxygen
comprising a generator element having a high voltage electrode, a ground
electrode
separated from the high voltage electrode to form a gap therebetween, and a
dielectric
element occupying a portion of the gap, the generator element being
electrically connected
to a circuit for producing an alternating current or pulsed direct current by
means of a
releasable connector, said high voltage electrode extending into a spacer, and
said
releasable connector connecting the high voltage electrode through said spacer
to said
1 p circuit.
In accordance with another aspect of the invention there is provided an
apparatus for
producing ozone from oxygen comprising a generator element having a high
voltage
electrode, a ground electrode separated from the high voltage electrode to
form a gap
therebetween, end a dielectric element occupying a portion of the gap, the
high voltage
electrode being electrically connected to a circuit for producing alternating
or pulsating
direct current, and a grounded current collector at an outlet to the generator
element.
In accordance with another aspect of the invention there is provided an ozone
generator
system comprising: a plurality of generator elements, each generator element
having a high
voltage electrode, a ground electrode separated from the high-voltage
electrode to form a
2p gap therebetween and a dielectric element occupying a portion of the gap;
and, a circuit for
producing alternating or pulsating direct current electrically connected to
the high voltage
electrode of each generator element, fiuther comprising a valve at the outlet
of each
generator, each valve being an electrical valve and in series with the
circuit; and, a
current-sensitive protection device in communication with the circuit and
valves for
interrupting the current to the circuit and the valves when the current
exceeds a
predetermined value.
2a
CA 02327558 2001-O1-04
In accordance with another aspect of the invention there is provided an
apparatus for
producing ozone from oxygen comprising a generator element having a high
voltage
electrode, a ground electrode separated from the high voltage electrode to
form a gap
therebetween, and a dielectric element occupying a portion of the gap, the
generator
S element being electrically connected to a circuit for producing an
alternating current or
pulsed direct current by means of a releasable connector, and a grounded
current collector
at an outlet from the generator element, wherein the dielectric member is a
tubular member,
accommodated within and in contact with the ground electrode, and the high
voltage
electrode is disposed within the dielectric member.
In accordance with another aspect of the invention there is provided an
apparatus for
producing ozone from oxygen comprising a generator element having a high
voltage
electrode, a ground electrode separated from the high voltage electrode to
form a gap
therebetween, and a dielectric element occupying a portion of the gap, the
generator
element being electrically connected to a circuit for producing an alternating
current or
1 S pulsed direct current by means of a releasable connector, wherein the
dielectric member is a
tubular member, accommodated within and in contact with the ground electrode
and the
high voltage electrode is disposed within the dielectric member, the generator
element
further comprises an end cap at each end thereof, each end cap is formed as a
block having
a chamber for passage of gas therethrough, each said block having an aperture
for insertion
of the dielectric member therein such that a continuous passage is formed
between the end
blocks, and further comprising a grounded current collector at an outlet from
the generator
element.
According to a broad aspect of the present
invention there is provided an apparatus for producing ozone
from oxygen comprising a generator element having a high
voltage electrode and a ground electrode separated from the
high voltage electrode to form a gap and a dielectric eleme:~.t
disposed therebetween and occupying a portion of the gap, the
generator element being electrically connected to a circwi= v
for producing an alternating current or pulsed direct current '
and the generator element being removable from the circuit.
2b
CA 02327558 2001-O1-04
According to a further broad aspect of the present
invention there is provided an apparatus for producing ozone
from oxygen comprising a generator element having a high
voltage electrode and a ground electrode separated from the
s high voltage electrode to form a gap and a dielectric element
disposed therebetween and occupying a portion of the gap, the
high voltage electrode being electrically connected to a
circuit for producing alternating or pulsating direct
current, the high voltage and ground electrodes being
~o impedance matched to the circuit.
According to a further broad aspect of the present
invention there is provided an apparatus for producing czone
from oxygen comprising a generator element having a high
~s voltage electrode and a ground electrode separated from the
high voltage electrode to form a gap and a dielectric element
disposed therebetween and occupying a portion. of the gap, the
high voltage electrode being electrically connected to a
circuit for producing alternating or pulsating direct
zo current, and a grounded current collector at an output of the
generator element.
According to a further broad aspect of the present
invention there is provided an apparatus for producing ozone
z5 from oxygen comprising a generator element havinc a high
voltage electrode and a ground electrode separated from the
high voltage electrode to form a gap and a dielectric element
disposed therebetween and occupying a portion of the gap, the
high voltage electrode being electrically connected to a
30 _circuit for producing alternating or pulsating direct
current, the chamber being provided such that its =nductance
and capacitance are selected to produce a waveform ~.-=thin the
gap having a high frequency component which is selected break
the oxygen - oxygen bond.
CA 02327558 2001-O1-04
According to a further broad aspect of the present
invention there is provided an apparatus for producing ozone
from oxygen comprising a generator element having a high
voltage electrode and a ground electrode separated from the
s high voltage electrode to form a gap and a dielectric element
disposed therebetween and occupying a portion of the gap, the
high voltage electrode being electrically connected to a
circuit for producing alternating or pulsating direct
current, the circuit having a saturable transformer with at
io least one feedback winding.
Description of the Invention
A generator is provided whic~: employs alternating
is current or pulsating direct curre~:t to produce ozone from
oxygen gas or oxygen-containing gas. The generator comprises
a generator element comprising a ground electrode and a high
voltage electrode spaced from the ground electrode and having
a discharge gap therebetween to accommodate the gas and a
zn dielectric member. In a preferred e~~odiment, the gererato~Y
element is of a tubular arrangement ~~~:herein the high voltage
electrode is disposed within the around electrode and the
dielectric layer is disposed therebetween. The aenerato=
element is formed to contain a gas any perm=t flow of the
zs gas, where desired, through the dischargelgap.
The ground electrode __ formed o. suitable
conductive metal or semi-conductive material. Where the aas
flow is passed in contact with the electrode, the around
~u electrode is made from a material, such as for example,
stainless stee-'_, which is ozone iner-~. In an embodiment of a
tubular generator arrangement, the ground electrode is formed
as a tube into which the dielectric and high voltage
electrode fit. In another embodiment, the ground electrode
3s is formed as a block and provides support fer the dielectric.
The block electrode is formed with a channel therethrough e=
CA 02327558 2001-O1-04
in sections having alignable grooves for accommodating the
dielectric.
The high voltage electrode is formed of materials
s similar to those of the ground electrode and is evenly spaced
from the ground electrode to provide an even capacitive load.
In a generator element having a tubular geometry the high
voltage electrode is formed to fit within the ground
electrode and a discharge gap is formed therebetween. To
~o provide an even capacitive load in the generator, the high
voltage electrode is maintained substantially centrally
within the ground electrode by any suitable means. In an
embodiment, the high voltage electrode is a wire held
centrally by means of centraiizer spirals formed of a:. inert
is polymer. Alternatively, dielectric centering blocks, such as
ceramic triangles or apertured discs, can be employed. In an
alternate embodiment, a spiral electrode is provided and is
maintained centrally by means of centering blocks disDOSed at
each end of the channel in which the electrode is mounted.
2o In such an embodiment, a dielectric member can be used as a
support for the spiral electrode by winding the electrode
about the member or by inserting the member into a prepared
spiral electrode. The member is solid and acts to prevent
the flow of gas -along the center aris of the chamber and
?s thereby directs the gas through electrical discharge between
the high voltage and the ground electrodes. In another
embodiment the centering blocks are formed integral ;Kith the
dielectric support member and the spiral electrode is wound
thereabout.
3U
The dielectric member which is positioned between
the ground electrode and the high voltage electrode acts as
capacitor together with the gas which is supplied to the
generator. In one embodiment, the d-lelectric is positionec:
3s in close contact with the ground electrode. Alternativel=,
the dielectric material is disposed about t:~e hig_-_ voltage
CA 02327558 2001-O1-04
electrode. The dielectric member is formed of a suitable
dielectric material such as a ceramic, glass or polymeric
material and is preferably separate or easily separable from
the electrodes to allow for independent replacement of the
s dielectric member apart from the electrodes and to facilitate
recycling of generator components. In a preferred
embodiment, the dielectric member is formed of mullite
ceramic.
io The generator is formed to contain gas in any
suitable way. In embodiments with a tubular geometry, the
gas passes between the tubular electrodes and ' is contained
therebetween by a pair of end caps. The end caps provide
ports for electrical contact and input and output o~ gas. In
n an embodiment, the end caps are formed as en~7 h~r,rk-~ T~r
supporting the generator element and containing means for
electrical connection and flow paths for the gas. The end
blocks can be formed to prevent direct access to the ~:~ner
components. The end blocks are formed of an ozor_e inert
zo dielectric.
Contact must be provided between the electrodes and
the generator circuit for producing the current for o=one
generation. Preferably:, such contact is releasable such that
zs when desired, the generator element of the present inve_-__ior.
can be removed fror;, the generator fcr maintenance and repair.
In an embodiment, a high voltage plug connection is employed.
A plug is mounted on th=_ generator element and in
communication with the high voltage electrode which is
3u disposed to make contact with a socket provided i:_
communication with the externa_ circuit. In a oreT=_rred
embodiment, the high voltage electrode is connected to the
circuitry by means c~ a high voltage pin. The pin has a
first end which extends =rom the generator to form a plot and
~s a second end for contacting the high voltage electrode. Suc:-_
contact can be a pressure contact made in the acerture _= a
CA 02327558 2001-O1-04
centering block into which the second end of the pin and an
end of the high voltage electrode are each inserted. Such a
contact arrangement avoids the need for soldering.
The electrode geometry in the generator can be
selected to create impedance in the generator circuit which
matches the impedance of the circuitry. In a plate generator
arrangement, the distance between the electrodes, the surface
area of the electrodes and the density of the electrodes,
~o such as for example, the use of mesh electrodes or solid
electrodes, can be selected to allow for impedance matching.
Impedance matching in a tubular generator can be accomplished
by selecting the pitch and length of a spiral high voltage
electrode or by winding a selected number of turns of a
~s conductive wire ir_ contact wit: t:~e high voltage or ground
electrodes. Such impedance matching enhances the energy
efficiency of the generator.
To dissipate the heat produced in the generator, it
2o is desirable to provide a heat sink arrangement in
association with the generator element. The heat sing: can
preferably also be an electrical around for the generator
and, as such, is provided in intimate contact with the ground
electrode but is detachable therefrom, when desired.
To prevent a shock hazard by use of the inven~ive
generator, should water enter the generator and make contact
with the high voltage electrode, a grounded current collector
can be provided at the gas outlet to ground the current. In
an embodiment, the currer.~ collector is formed as a
electrically conductive conduit ~~r carrying output gas and
is grounded by contact with the ground electrode of the
generator. In another embodiment, the current collector is a
conduit formed integral with the ground electrode and i_~.
3s engagement with the end blocks.
7
CA 02327558 2001-O1-04
All components of the generator which are in
contact with the gas must be built having regard to the
corrosion problems of the gas to be introduced and the ozone
formed in the generator, as is known in the art.
The generator is of use with pulsating direct
current or alternating current. In a preferred embodiment,
oxygen-oxygen bonds are selectively broken by use of a high
frequency, high voltage alternating current or pulsed direct
io current discharge which is selected to have a waveform having
a fast rise leading edge suitable for breaking the oxygen -
oxygen bona. The fast rise portion cf the waveform creates a
range of high frequency components defined by the rate of
change at each point on the slope ir_ conjunction with the
i5 repetition. rate and the amplitude of the waveform. The time
that the leading edge of a wavefor:n is maintained at any
given frequency combined with the voltage at that point give
a potential energy transfer rate.
2ca ~o break the oxygen-oxygen bonds the leading edge
of the waveform is selected tc nave a high frequency
comDOnent which breaks the oxygen molecules apart, termed the
"active frequency" or "active high frequency component".
This active Frequency must be.appiied at a suitable voltage
zs and be maintained for a sufficient time to transfer enoug~~
energy to the molecule to breal~; the bond.
it is believed that the active high frequency
component is close to a primary cr harmonic of the natural
zo oscillating frequency of the oxygen-oxygen bond and therefore
creates constructive interference w.,ith the oscillation of any
oxygen-oxygen bonds which are ~_. phase with the applied
active freauency. It is believed that suitable active
freQUencies are at least i~ the megahertz range. This active
frequency is applied at a suitable voltage and is maintained
for a sufficient time to trans=e= enougenergy t~ the
;;
CA 02327558 2001-O1-04
molecule to break the bond. It is believed that the suitable
voltage is at least 3 times the combined strength of the
bonds to be broken. It is further believed that an avalanche
effect is created wherein further oxygen-oxygen bonds are
s broken by those broken through the application of the active
frequency. In such an effect, the release of bond energy
causes the separated oxygen atoms to be high in energy and to
collide with other oxygen molecules that are weakened from
the application of the current. Due to the collision, the
~o oxygen-oxygen bonds of the weakened molecules are broken.
Since it is believed that the applied active freauency can be
a harmonic of the natural oscillating frequency, it is also
believed that there are many active frequencies that are
suitable for interference with the. oxygen.-oxygen bond, as
is there are many harmonics of that bond.
In an ozone generator employing a current having an
active high frequency component, it is believed that
substantially only oxygen - oxygen bonds are broken, even
zo where other molecular species are present. However, due to
ionization in the chamber and the impact c. high energy
oxygen atoms, some side reactions may occur suc~ as the
production of nitrous oxides.
25 In an emi~odiment, a periodic wave for-. is generated
having a leading edge selected to represeT~ a:: active
frequency for breaking oxygen - oxygen bonds and sufficient
voltage to break the bond once it is applied. In a
continuous system, wherein oxygen molecule= are being
:~o converted to ozone and passed on, the fiov:~ rat. c' the
molecules through the chamber must be consi.er~d and the
. voltage should be increased accordingly, to expose each
portion of the gas containing the oxygen ;molecules to
sufficient voltage Lo initiate bond breakage bef~:~re the gas
~s passes out of the generator.
9
CA 02327558 2001-O1-04
In order to carry out the process of the bresent
invention, the generator circuitry is set to apply an
alternating or pulsed direct current having a fast rise and
sufficient voltage. To obtain an active high frequency
s component and optimize the waveform for ozone production, the
repetition rate of the waveform or amplitude of the current,
or inductance or capacitance of the circuit, transformer or
generator can be adjusted while analyzing ozone production by
use of a chemical analyzer, such as a mass spectrometer or
to ozone monitor. In a preferred embodiment, the inductance and
capacitance are maintained constant, while the repetition
rate and amplitude are adjusted to obtain an active high
frequency component. Once the generator is set, the ozone
production can continue without modification at substantially
is similar operating pressure and temperature. Ar_y changes in
the voltage or the repetition rate of the applied discharge
or changes in the inductance or capacitance of the circuit,
generator or transformer, including changes in pressure or
generator load, require recptimization of the waveform to
zo re-establish the active high frequency component. Such
readjustment can be made manuall;r or by use of a circuit
feedback arrangement. In addition, in generators produced
with similar geometr~~, the circuit can be optimized once and
incorporated into eat:: further generator without resetting.
Iri One embodiment c CaTJaCitlVe-induCtl.Ve reSOnati.nQ
circuit is used to produce a carrier waveform raving the
required active frequency for the ozone production. The
circuit is powered by any suitable power supply or source.
3o The resultant waveform can be an alternating current o= a
pulsed direc t curre_~_. having a f as t rise leading edge . I:. a
preferred embodiment, the curren~ is a pulsating direct
current having a_-_ active frequency component ant is
preferably generates a~d maintained, by an electronic circui=
ss employing a saturable trans=ormer having a feedback winding.
The his =reauency~ cor"ponen t is produced b-.~ " swi tc::ing o~ "
CA 02327558 2001-O1-04
transistor until the core of the transformer is magnetically
saturated, as determined by the feedback winding or windings
and the connected generator. The "switch on" initiates
oscillation at the circuit resonance frequency and once
s initiated the energy from the core of the transformer
maintains the reaction. In an alternate preferred
embodiment, the current is a high voltage direct current
having the active frequency component added thereto.
to In the preferred embodiment, the generator acts as
the capacitance in a parallel resonant circuit with the
secondary winding of the transformer forming the inductor.
The capacitive and inductive characteristics of the generator
cell and inductor are chosen such that the circuit is
is essentiall;~~ resistive at the resonant, active frequency.
Energy transfer to the gas produces some heat and causes
ozone production by interfering with and breaking the oxygen
- oxygen bond.
2o Since the presence oT gas alters the capacitance of
the resonant circuit, the electronic circuit o-_' the present
invention is capable of compensating for chances in the
reactor loading such as the gas fiov:: rate, gas density, gas
composition or gas temperature by sensing the changes in the
2s dielectric constant of the gas. Any changes in the
dielectric constant o. the gas cause_-- the c~.~rrent of the
discharge in the generator to change, and hence the feedback
winding changes the operating repetition rate to maintain. the
required active frequency for ozone production.
F flowing stream of gas ca:: pe fed to the generator
such that a continuous process for ozone production. is set
up. To increase the output of ozone by the generator, the
length o~ the generator element ca.~_ be extended or a
3s plurality of generator elements can be provided in series or
parallel. In such arrangements, an e~~ectricai control can be
CA 02327558 2001-O1-04
provided to detect malfunction: and cause the'generator to be
shut down.
Brief Description of the Drawingrs
s
A further, detailed, description of the invention,
briefly described above, will follow by reference to the
following drawings of specific embodiments of the invention,
which depict only typical embodiments of the invention and
io are therefore not to be considered limiting of its scope. In
the drawincrs
Figure 1 shows a prior art ozone generator;
is Figure 2 shows another prior art ozone generator;
Figure 3 shows a sectional view along the axis of an
embodiment of a generator element according to the present
invention;
zo
Figure 4 shows an exploded, perspective view of another
embodiment of a generator according to the present invention;
Figure 5 shows a sectional vie:: through an end bloc:: of
zs an embodiment of a generator according to the present
invention;
Figure 6 shows a perspective view of a modular generator
according to the present invention with a panel of the
~a housing removed to sho~:: the inner components;
Figure t shows a schematic diagram of a generator system
according to the present invention;
3s Figure 8 shows an oscilloscope representation of a
waveform useful i.~. the prese_-.= inve_-_~tior.;
CA 02327558 2001-O1-04
Figure 9 shows a circuit diagram of an electronic
circuit useful in the present invention; and,
Figures l0A and lOB show oscilloscope representations of
s waveforms useful in the present invention.
Detailed Description of the Invention
Referring to Figure 3, a perspective view of a
~o generator element according to the present invention is shown
comprising an outer grade electrode 210, an inner high
voltage electrode 212 and a dielectric member 214
therebetween. Ground electrode 210 is formed as a ~~PPVP
which is in telescopic arrangement with dielectric member 214
n but is removable therefrom. High voltage electrode 212 is a
straight length of metal such as stainless steel and is held
concentrically within the dielectric member 214 by means of
spiral centralizers 216 formed of plastic. End caps 218 are
provided at the ends of the element tc seal against the
~o passage of gas out of the bore of the dielectric member 214.
Ports 22C, 221 are formed in end caps 2".~c for mountinc gas
supply and output lines 222, 223, respectively. Electrical
connectors 224 are mounted on end caps 218 for connectic.~. to
electrical lines 225.
~5
Gas containing oxygen flows into ti:e generato~-
through port 22C and passes through the bore of dielectric
member 214. Alternating current or pulsating direct current
is applied between electrodes 210 and 213, by contact with ar_
:~o external power source through connectors 224 and lines 225,
and through the gas causing ionization and modificatio_~. of
the molecular species present in the gas. Gas containinc
ozone moves out of the generator through the exit port 221.
A conductive iaye= 228 is provided about the inner surface of
~s es:=~~ port 221 which is in contact with ground electrode 21C
CA 02327558 2001-O1-04
via wire 229 and thereby provides fer collection of current
if water passes through it into contact with electrode 212.
When replacement or repair of the generator
s components is required, the generator is shut down, such as
by stopping supply of gas and power and removing the supply
lines. The end caps are removed and the defective parts are
removed, including possibly the entire generator element. A
new generator element can then be connected and the
~o generation process re-initiated.
Referring to Figure 4, a preferred generator for
ozone production i= shown. The generator comprises ar.
apparatus 23 for producing a current comprising a waveform
is having ar. active frequency componen " a reaction chamber 24
and a heat sink arrangement 26 associated with apparatus 23
and reaction chamber 24.
Reaction chamber 24 comprises ground electrodes 33
2o and 34 having corresponding groove= formed t~erei~ fer
accommodating and contacting die 1 ectric tubu'~a= me.."ber 3c .
Electrodes 3, 34 are secured about member 36 by- poi riveis
38 and 40.
zs Disposed ~~:ithin member ~.. is high voltage spiral
electrode 4= consisting of ozone inert meta_ su.... as
stainless steel. The pitch and length of electrode 42 is
selected to impedance match the impedance o= apparatus ''3.
In addition, the -~ength of electrode 4~ is selected to
3o prevent node reflection at the reauired dischara=_ wave=orr~;.
A screw 43. forme:i of a suitable dieiectr~_c material ,1s
inserted through a t~readed aperture 4~ in end block ~:; to be
in engagemer:t wit: an end 52 of electrode 42 whicallows
externa~~. adjustme-t of the length and pitch of electrode 4..
ss A dielectri_ member 4z acts as a Filler and support =cr
Splra! eleC.'_rOQe 4L . An enC DOr tlOr~ =.. G. SDlra_ __e'troQ°_
~a
CA 02327558 2001-O1-04
42 is inserted into central aperture 48 of centering triangle
50. The other end 52 of spiral electrode 42 is inserted into
central aperture 54 of centering block 56. Tubular
dielectric member 36 containing spiral electrode 42 and
s associated parts 44, 50, 56 is inserted between apertures 66,
68 of end blocks 58 and 60, formed of suitable dielectric
material, respectively. Sealing means, such as 0-rings 62,
64 are provided to seal the connection between tubular member
36 and the end blocks against passage of gas. Other sealing
io means can be used such as, for example, silicone sealant. A
high voltage pin 70 is inserted into aperture 48 of centering
block 50 to be in electrical communication with end 46 of
spiral electrode 42. The other end of pin 70 extends
through, and is engaged within, an aperture 71 in end block
i5 58 for electrical communication with apparatus 23.
A current collector 72 formed as a tubular member
from corrosion resistant conductive metal is sealably secured
such.as by press fitting at its ends into apertures 74 and 76
20 of ends blocks 58 and 60, respectively. Current collector
acts mechanically to join and form a gas conduit between end
blocks 58 and 60. Electrodes 33 and 34 accommodate and make
contact with c~,:rrent collector 72. Since electrodes _~ and
34 are at grcund potential durinc operation and are =r.
2s intimate contact u:ith current collector 72, current collector
72 serves to prevent electrical c~.~rrent from passing our of
the generator element during use.
Referrinc to Figures 4 and ~, a stream c_ gas
3o containing a. least a portion of oxygen is provided to the
generator throug~ entry nozzle 78 into an upper chamber 7? c.
block 6G. Unner chamber 79 of the block 60 is former
generally a= ar_ "L "shaped chamber having an extending
portion 79a whir: impedes insertio:: of articles, sucas
ss wires, into the generator to contact high voltage elec=rode
42 . Stil 1 refers ing to Figur a 3 , screw 4 is inserted ...,._
CA 02327558 2001-O1-04
aperture 45 to be in contact with electrode 42. Electrode 42
is maintained in a recess formed in an end of screw 43 and is
held therein by the resiliency in electrode 42. The length
of electrode 42 can be altered by changing the extent to
s which screw 43 is inserted into end block 60.
The gas is directed into and passes through
dielectric tubular member 36 and about spiral electrode 42
into end block 58. Dielectric member 44 acts within
io dielectric member 36 to dire~t the gas into close association
with spiral electrode 42. The spiral configuration, in
addition to providing impedance ir. the generator, acts to
create turbulence in the passinc gas stream and thereby
enhance mixing. Such mixing al-~.ows for increases heat
o transfer from electrode 42 to electrodes 33 and 34 which are
cooled by heat sink 26. Gas returns along the bore of
current collector 72 to enter a loc~:er chamber 73 of block 60
where an outlet 77 is provided from the generator. Gas
passing through this system is reacted when passing through
zo dielectric tubular member 36 preferably by application of a
selected active frequency current applied through electrode
42. Current is pro~~ided to eiectrcce 42 by apparatus 23.
Apparatus 23 for producing current is of any
suitable kind. I~. a preferred eT.bodiment, apparatus 23 is
comprised of a circuit, as wild be described in reference to
Figure 9, including among its components a high voltage
transformer 80, a low voltage t=ansformer 82, a bridge
rectifier 86, a sc,;itch 109, tra~:sister 90 and associated
~o electronics 88. Th--__ low voltage transformer 82 is provides
with fluctuating ~oower such as a-_ternating current by means
of plug 84. Th= current produced b-_r apparatus 23 is
communicated to the generator through a high voltage wire 96
having a plug socket 98 on an end t.~.ereof for making contact
;s with high voltage pin 7G in e=.~ block 58. Switch 109
interrupts t:~~e power =lowing =ro:-, t::e transformer 82 to the
W
CA 02327558 2001-O1-04 -
electronics 88 when end block 58 is moved away from plug 98.
Thermal switch 112 on heat sink 26 interrupts power flowing
from transformer 82 when the temperature in the generator
exceeds a predetermined level.
s
When the high frequency, high voltage current is
applied to the gas in the generator, heat is generated. A
heat sink 26 is provided in association with reaction chamber
24 to reduce temperature fluctuations in the generator. Heat
~o sink 26 comprises a thermally conductive tube 121 which is
inserted into a heat sink block 122. A suitable ccnlanr ;s
circulated through tube 121. Holes in the heat sink block
122 include a threaded hole 123 to mount the transistor 90
and a threaded hole 125 to mount the bridge rectifier 86.
is Heat sink block 122 is firmly mounted to ground electrodes 33
and 34 through conductive screws 126 which also act to ground
electrodes 33 and 34. Screws 126 are easily removable to
allow removal of generator element.
za Referring to Figure 6, in the preferred embodiment,
the generator is provided in the form of a module tc
facilitate installation. The module comprises a housing 600
(shown with the top removed> formed of durable material such
as thermoplastic. Housing 600 provides encasement for an
zs apparatus 623 for producing current, a generator element 624
and a heat sink arrangement 626. E~a ending from housing 600,
for connection to external supply lines, are plug 684 and
ends 621a and 621b of thermally conductive tube 621.
Additionally, end block 660 of generator element 624 extends
so from housing 600 to allow connection of gas lines to entry
nozzle 678 and outlet 677. Generator element 624 is
removably ir_stalled within housing 600 by insertior_ through
aperture 697 and into abutment with upstanding stop 699
(generator element 624 is shown partially inserted in Figure
,i 6?. Stop 69°, formed of a suitab_e dielectric, supports high
voltage plug socket 698 which is a'~igned for contact wit: a
CA 02327558 2001-O1-04
high voltage pin extending through an aperture of end block
658. When in place screws 6126 are inserted through a side
wall of housing 600 to engage heat sink 626 and the ground
electrodes of generator element 624. A pressure sensitive
s switch 6109, disposed adjacent stop 699, interrupts the power
to apparatus 623, when generator element 624 is not fully
inserted into housing 600 such that the high voltage pin is
not inserted into socket 698. Such a generator element
installation arrangement allows for removal and replacement
~o of chambers, when desired, without affecting the circuitry or
heat sink components.
As shown schematically in Figure ", the cutput of
ozone by the present ozone generator can be increased by
is providing a generator system comprising a plurality of
generator elements 724a, 724b and 724c in series. Problems
in scale-up, such as reconfiguration of enlarged generators,
are thus avoided by installing optimized generators in
greater numbers. To control the passage of untreated gas
~o through the system, in case of system fa,_lure, valves 799a,
799b and 799c are provided at the cutlet cf each generator
element so that gas can flow from element 724c through
element 724b and then through element 724a. These valves are
held open in no-rural operation by power supplied via line 797,
~s which is in~_ series with the apparatus 723 for producing
current. Where th=_ system fails, suc~. as bv.- dielectric
breakdown, a current-sensitive protective device 79~, such as
a fuse or circuit breaker, in the power supply 793 senses the
increase in current and stops power to the system. Valves
30 799a, 799b, and 799c then stop the flow of gas through the
chambers 724x, 724b and 724c unti-_ the flow c. current is
resumed, thereby preventing output ef anw unreacted gas
through the system.
1Q
CA 02327558 2001-O1-04
Referring to Figure 8, a waveform is shown which is
useful in the selective breaking of oxygen-oxygen bonds in
oxygen molecules to produce ozone. The active portion of the
waveform is shown between A and B. From the oscilloscope,
s calculations of the slope of the substantially straight rise
portion of the leading edge between A and B indicate that the
rate of voltage increase over this portion is in the order of
6
6.6 x 10 volts/second. Such an active portion is believed
to correspond to a frequency in the order of 10 to 100
io megaHz. The waveform is applied at a repetition rate of
about 6.67 kHz to air at a temperature of 26'C and
atmospheric pressure to produce ozone. Ozone generation is
enhanced by applying the waveform to air at lower
temperatures. The generator of use.;:ith the waveform having
~s parameters as shown is generally as shown in Figure 4 and is
4 to 8 inches in length having a corresponding length high
voltage electrode having 22 turns and formed from .036 inch
stainless steel wire.
zo Referring to Figure 9, a preferred embodiment o. a
circuit is shown. for use in generating curren~ comprising a
waveform as shown in Figure 8. The circuit comprises a
Darlington pair transistor T1 and a ferrite core transformer
TR1. The transformer TR'_ has four windings, the primary
2s winding 30G, a secondary (output! winding 31G, and twa
feedback windings 32G and 330. The primar_.~ winding 300
connects the collector of the traiaistor Tl to the positive
power supply voltage. The secor_dar~.~ winding 31G is the
output of the generator circuit and is applied to one of the
:~o electrodes of the reactor cell shown. in Figure ~. The
feedbag: winding 320 is connected via diode D~ and R3 to the
base of the transistor T1.. The other terminal a. the feedback
winding 320 is connected to the biasing circuit o. the
transistor T'~, which comprises variable resistor V?.1,
3s resistor R. and resistor R2, as well as silicon sc~.itchina
diodes D1, Dl and D3. The ieedbac:~ winding 33'.,' connects the
19
CA 02327558 2001-O1-04
emitter of the transistor T1 to the negative terminal of the
power supply. The circuit operates as follows.
Transistor T1 is present to permit the generation
s of a fast rise waveform. In a circuit which is intended to
produce pulsed DC waveforms, one transistor T1 is used. If
it is desired to produce AC waveforms, a second transistor
(not shown) is used. As the transistor T1 is handling a high
peak current, a heat sink to dissipate the heat generated by
~o such current should be used.
Transformer TR1 is a saturabie transformer having a
ferrite core material with very io4: losses. In a preferred
embodiment, TR1 has a ferrite core comprising a 7 turn
a primar;.~ winding 300, a 3 turn feedback winding 320, a 1 turn
feedback winding 330 and a secondary winding 310 having 3300
turns of 22 gauge wire.
The diodes D1, D2, D3, and D4 are silicon s~~:itching
zo diodes that are selected to have voltage and temperature
characteristics ~,~riich correspond the Darlington Transistcr.
Diodes D1, D2, and D3 give a regulated "switch on" voltage
for transistor T1. Diode D4 acts to prevent the negative
feedback voltage turning the base-emitter junction c~
~a transistor T1 back "on" by reverse voltage avalanche
breakdow:~. Any similar silicon switc:zing diode to IN914 ca_~.
be used for diodes D1, D2, D3, and D4.
Variable resistor VF.= and fixed resistor _..
3o regulate the curre.~= to maintain the voltage across the
diodes and bias tre base of the transistor T1. 'variable
resistor VF.1 is used to set the operating current,
compensating for different gain of transistors. Resistor F__
acts to limit the current when variable resistor VR'_ is set
:~s to 0. Alternatively, a fixed value resister o= suitable
?u
CA 02327558 2001-O1-04
resistance for the transistor used, can replace both R1 and
VR1.
Feedback winding 330 is connected to the emitter of
s the transistor. It provides compensation for change of gain
versus temperature, and provides some compensation for
transistors of different gain. Winding 330 is most useful in
high power reactors. However, since it also acts to damp
harmonics in the system, which would interfere with the
to desired active frequency, it is preferably included in all
circuits.
Capacitor C1 reduces variations __. the supply
' voltage reaching the base of transistor T1 during normal
is operation. This is important in high current aenerators.
Due to the high switching current, smoothing capacitors Cl
and C2 much each handle high peak ripple currents and must be
rated accordingly.
'o Power is applied to the circuit by ar. r.C source, as
shown. The current within the circuit is preferably I? t,rol=
DC. Therefore where I20 volt power is used a step dow-
transformer is required prior to the bridge rectifier BP.'_.
The bridge rectifier is useful even where the power suppl~_~ _s
?s a battery, since the rectification allows connec~ion of t:ne
battery without concern as to matching terminals.
After power is applied to the circuit, the base e.
transistor T1 ,_s driven positive and the collector curre_~..
3o increases. For the purposes of this description, == __
assumed that the circuit has been operating for some time ar_~
that we are starting the description from the point where the
base of transistor '~" is being driver_ pcsitiv~ and th=
collector current is increasina.
_i
CA 02327558 2001-O1-04
With transistor T1 fully switched on, the current
through the primary winding of TR1 transformer increases at a
rate set by the transformer inductance and the generator
capacitance. As the current increases, the transformer core
s magnetizes, and a voltage is induced into the base feedback
winding 320. The negative going end of feedback winding 320
is connected to the voltage reference diodes D1, D2, D3 and
the positive going end connected through diode D4 to resistor
R2 and the base of transistor T1. Thus, an induced voltage
~o in feedback winding 320 acts to maintain transistor T1 "on".
The actual drive current is set by the value of the resistors
VR1 and R1.
Resistor R3 together ~~~.th the base input
~s capacitance of transistor Tl reduces current oscillation at
very high frequency during switching. Preferably, resistor
R3 is connected directly at the base of transistor T1.
As the transformer core approaches saturaticrl, the
zo rate of current increase drops. As _~ drops, the induced
voltage in the base feedback winding reduces thus reducing
the drive to the transistor which then starts to turn of~.
This reduces the rate o~ increase of the collector curren:.
through primary winding 300 and thi= in turn fur'her and
?5 further reduces the feedback voicage. This very rapidi-~.~
turns the transistor fully of.. As t~°_ core magnetic field
is no longer being maintained by the transistor, the magnetic
field collapses reversing the voltage in the base feedbaci=
winding 320 and placing a negative voltage on the anode o.
3u -diode Da turning it o_= thus keepinc transistor T~~ Lurned
off. This also effectively unloads the feedback winding 32C
and prevents any damping of the noc~; oscillating secondar;
winding 310.
3S
CA 02327558 2001-O1-04
As the current drops towards zero across the base
of feedback winding 320, the generated negative voltage
across the back feedback winding 320 decreases until it no
longer cancels the bias voltage at the cathode of diode D1.
s When this happens, the transistor starts to turn on. As it
does, the current starts increasing and this in turn reverses
the voltage in the base feedback winding 320. This applies
additional positive voltage to the base of transistor T1
turning it fully on and into full saturation. Now the
io transistor is turned fully on and the collector current
increases, which is where the cycle repeats.
The invention will be further illustrated by the
following examples. While the examples illustrate the
is invention, they are not intended to limit its scope.
Example 1
Air at atmospheric pressure and 26'C was
2o dehumidified such that it had a de~~~ point between 35° and
40'F. The air was introduced t_ an ozone generator,
generally as described in reference tc Figure 4, at a fiov.°
rate of 31/min. Air exiting the generator was passed to ar_
ozone monitor for analvsis.
Electrical discharges were applied to the air as
follows
1. ~: sinusoidal waveform having a frequency of 60 Yz and
so varied between 5,000 and 8,000 volts;
2. A sinusoidal waveform having a Trequency of 6.5 kH= and
ranging between 5,000 and 8,000 volts;
ss 3. i: square waveform having a =requency of 6.5 kLz and
ranging between 5,000 and 8,000 volts; or,
CA 02327558 2001-O1-04
4. A waveform according to Figure 8 at a repetition rate of
6.67 kHz and an amplitude of 4,500 volts.
Typical ozone production results by use of
s waveforms 1 to 4 for treatment of air are summarized in Table
1.
Table 1
io Waveform Ozone Concentration
by weight)
1 0.001
2 0.066
~s 3 0 . 066
4 0.332
Conversion rates were increased by use of the fast
rise waveform according to the presen~ inventive process.
zo
Example 2
Air at atmospheric pressure and 22'C and having a
relative humidity of 80~ was introduced at a flow rate of 3.~
zs 1/min to ozone generators, generally ~as described in
reference to Figure S without the use of a heat sink and
having the parameters as set out in Tap'~e 2.
35
CA 02327558 2001-O1-04
Table 2
Ozone generator A Ozone generator B
s Length 12 inch 4 inch
Capacitance 147 pF 34 pF
(at frequency=0)
Resonance 58.2 Mhz 66.0 Mhz
Inductance 0.0508 uH 0.170 uH
~o
The measurements for the generators were carried out in 18'C,
atmospheric pressure and 70~RH using a MIC 37 multimeter and
a MFJ HF/VHF SWR analyze., to measure capacitance and
resonance,. respectively. Inductance was calculated.
l5
The waveform was monitored using a Phillips PM3365A
100MHz Oscilloscope set at 5 VDC and .lms connected to a
Techtronix P6015 1000x probe. Air exiting the generator was
passed to an ozone monitor for analysis.
The waveforms which were found to produce optimum
amounts of ozone for generator A and generator B are shown in
Figures l0A and 108, respectively. The waveform parameters
and ozone production results are shown in Table 3.
30
,;
CA 02327558 2001-O1-04
Table 3
Ozone generator Ozone
generator
A B
Repetition rate (Hz) 1603 1637
Voltage (kV) 20 22
Leading edge rate of
voltage increase (V/s)* 234 x 106 233.5 x 106
to
Ozone concentration
(~ by weight) 0.190 0.145
* determined from oscilloscope
is
The active frequency for ozone production is
uniform for gas having the same composition, flow rate,
temperature and pressure regardless, of the reactor
parameters. The active frequency can be determined for each
zo reactor by adjusting the amplitude and repetition rate.
Examt~le 3
Air .at atmospheric pressure and 22'C and having a
zs relative humidity of 80~ was introduced at a =low rate of 3.8
1/min to ozone generator A as described in Example 2. The
waveform was monitored using a Phi'ylips PM3365A i00M~-iz
Oscilloscope set at 5 VDC and .lms connected to a Techtroni~:
P6015 1000x probe. Air exiting the generator was passed to
3o an ozone monitor for analysis.
The waveform was changed from waveform 1, having a
slower rate of voltage increase than the waveform oL Figure
10A, to waveform 2, according to Figure 10A, by adjusting the
3s power to the generator. Results are shosrm in Table 4.
26
CA 02327558 2001-O1-04
Table 4
Waveform Ozone Concentration
( % by v'eiQht )
s
1 0.021
2 0.190
It will be apparent that many other changes may be
~o made to the illustrative embodiments, while falling within
the scope of the invention and it is intended that all such
changes be covered by the claims appended hereto.
~s
25
35
37
