U.S. patent application number 10/217766 was filed with the patent office on 2003-01-09 for method and apparatus for ozone generation and contaminant decomposition.
Invention is credited to Zante, Anthony A..
Application Number | 20030009075 10/217766 |
Document ID | / |
Family ID | 26850188 |
Filed Date | 2003-01-09 |
United States Patent
Application |
20030009075 |
Kind Code |
A1 |
Zante, Anthony A. |
January 9, 2003 |
Method and apparatus for ozone generation and contaminant
decomposition
Abstract
A method of and apparatus for generating ozone from oxygen or
air with irradiation such as from an electron beam. A means for
cooling and preferentially positioning oxygen or air to increase
ozone yield efficiency and concentration is employed. The disclosed
method and apparatus may also be used for other process
applications including waste gas and wastewater
decontamination.
Inventors: |
Zante, Anthony A.; (Dublin,
CA) |
Correspondence
Address: |
Gregory Smith & Associates
3900 Newpark Mall Road, Suite 317
Newark
CA
94560
US
|
Family ID: |
26850188 |
Appl. No.: |
10/217766 |
Filed: |
August 12, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10217766 |
Aug 12, 2002 |
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09653059 |
Sep 1, 2000 |
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6432279 |
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60173114 |
Dec 27, 1999 |
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Current U.S.
Class: |
588/309 ;
422/186 |
Current CPC
Class: |
B01D 2251/104 20130101;
C01B 13/10 20130101; B01D 53/007 20130101; C02F 2201/782 20130101;
A61L 9/015 20130101; B01D 2259/812 20130101; B01D 53/50
20130101 |
Class at
Publication: |
588/227 ;
422/186 |
International
Class: |
B01J 019/08; A62D
003/00 |
Claims
1. A method for destruction of or decomposition of contaminants
contained in a fluid by irradiation comprising the steps of: a.
exposing said contaminants to an irradiation source whereby it is
irradiated to be destroyed or decomposed, and, b. simultaneously
flow said fluid containing said contaminants by means of a
pressurized force into a path surrounding said irradiation source
with a means for causing higher density contaminants to move to
outer perimeter of said path whereby contaminants are
preferentially exposed to said irradiation so as to minimize depth
of penetration required for irradiation source.
2. Irradiation source of claim 1 is an electron beam source, x-ray
source, or gamma ray source irradiating inwards from outside said
flow path lying within said irradiation source.
3. Pressurized force of claim 1 is generated by a pump, compressor
or static head source that causes said to flow at a desired
rate.
4. Means for causing higher density contaminants to move to outer
perimeter of said path of claim 6 and lower density fluid to move
to inner perimeter of said path comprising a curvilinear path in a
cylindrical or spiral or similarly formed path that causes
centripetal force to act on said fluid and contaminants whereby
producing said movement.
5. An apparatus for improved ozone production from oxygen or air or
for fluid treatment comprising: a. an irradiation source b. a flow
channel shaped in a spiral or otherwise circular pattern
surrounding or lying in the center of said irradiation source
whereby when oxygen or air or any other fluid flows into said
channel it provides the means to: 1) transport oxygen or air or any
other fluid past said irradiation source to generate ozone or to
otherwise treat said fluid 2) cool said ozone and oxygen or air or
any other fluid to reduce decomposition due to heat. 3) create
centripetal force to move higher density formed ozone or other
fluid to outer perimeter of channel whereby further irradiation
leading to decomposition is minimized in the case of ozone, and to
move lower density oxygen or air or other fluid or fluids to inner
perimeter of channel whereby further irradiation is maximized to
increase ozone production or other fluid treatment. Conversely, for
fluids of higher density that are to be processed, said irradiation
source surrounds said flow channel and preferentially irradiates
said fluid. c. a cooling channel to dissipate heat absorbed from
flow channel, whereby said flow channel lies between said cooling
channel and said irradiating source.
6. The apparatus for improved ozone production of claim 5 wherein
said irradiation source is a circularly shaped electron beam
generator that fits within said flow channel comprising the
following: a. Cathode, with or without control grid located in the
center of the generator that radiates electrons outward in a
circular pattern toward the anode b. circular anode surface
surrounding cathode with a gap separation from cathode and
including a thin window for transmission of electrons through it c.
evacuated chamber structure which maintains the cylindrical shape
of the electron beam generator
7. The apparatus for improved ozone production of claim 5 wherein
said irradiation source is a hollow circularly shaped electron beam
generator that surrounds said flow channel comprising the
following: a. cathode, with or without control grid in a circular
pattern that radiates electrons inward toward the center of the
generator in a circular pattern toward the anode. b. circular anode
surface lying within the cathode circular surface with a gap
separation from cathode and including a thin window for
transmission of electrons through it c. evacuated annular chamber
structure, which maintains the hollow cylindrical shape of the
electron beam generator.
8. The apparatus for improved ozone production of claim 5 wherein
said irradiation source is a circularly shaped X-ray generator that
fits within said flow channel comprising the following: a. cathode,
with or without control grid located in the center of the generator
that radiates electrons outward in a circular pattern toward the
anode b. circular anode surface surrounding cathode with a gap
separation from cathode and including an X-ray converting surface
to convert electrons to X-rays that penetrate through it into said
flow channel. c. evacuated chamber structure which maintains the
cylindrical shape of said X-ray generator
9. The apparatus for improved ozone production of claim 5 wherein
said irradiation source is a hollow circularly shaped X-ray
generator that surrounds said flow channel comprising the
following: a. cathode, with or without control grid in a circular
pattern that radiates electrons inward toward the center of the
generator in a circular pattern toward the anode. b. circular anode
surface lying within the cathode circular surface with a gap
separation from cathode and including an X-ray converting surface
to convert electrons to X-rays that penetrate through it into said
flow channel. c. evacuated annular chamber structure, which
maintains the hollow cylindrical shape of, said X-ray
generator.
10. The apparatus for improved ozone production of claim 5 wherein
said irradiation source is a circularly shaped gamma generator that
fits within said flow channel comprising a radioactive source such
as cobalt 60.
11. The apparatus for improved ozone production of claim 5 wherein
said irradiation source is a hollow circularly shaped gamma
generator that surrounds said flow channel comprising a radioactive
source such as cobalt 60.
12. The apparatus for improved ozone production of claim 5 wherein
said flow channel is constructed of a thermally conductive metal
such as copper that forms a spiral or otherwise cylindrical path
around said irradiation source and is shaped to allow entry of
irradiation with minimal irradiation losses to said flow
channel.
13. The apparatus for improved ozone production of claim 5 wherein
said cooling channel is metal or plastic construction with a
coolant inlet into a leak tight housing that is adjacent to said
flow channel and on opposite side from said irradiation source
allowing an annular passage for liquid or gaseous coolant to flow
directly past circular wall of said flow channel to dissipate heat
from said flow channel.
14. The apparatus for improved ozone production of claim 5 wherein
said outer cooling channel is metal or plastic construction with a
coolant inlet into a leak tight housing that surrounds said flow
channel allowing an annular passage for liquid or gaseous coolant
to flow directly past exterior of said flow channel to dissipate
heat from said flow channel.
Description
CROSS REFERENCE TO OTHER APPLICATIONS
[0001] This application is a continuation application of utility
patent application Ser. No. 09/653,059 filed Sep. 1, 2000, which
application claims the benefit of U.S. provisional patent
application No. 60/173,114, filed Sep. 7, 1999.
FIELD OF THE INVENTION
[0002] This invention relates to the production of ozone (O.sub.3)
and decomposition of contaminants, specifically to methods and
apparatus for using density differences in fluids combined with a
cylindrically configured irradiation apparatus for improved
production of ozone from air or oxygen and for decontamination.
Ozone is used as a treatment for drinking water, wastewater, and
related applications where it interacts with organic impurities to
implement disinfection. Decontamination applications include
removal of gaseous pollutants such as sulfur dioxide from effluent
gas and volatile organic compound decomposition in water,
wastewater, air and other gases.
BACKGROUND OF THE INVENTION
[0003] Currently there is only one widely used process for the
generation of ozone for water treatment and other commercial uses.
This process is referred to as "corona discharge" or "silent
discharge". In this process the oxygen or air is introduced to a
high voltage environment where the high voltage causes the gas to
"corona" at areas of concentrated electric field which leads to
break down and arcing between the negative electrode (cathode) and
the positive electrode (anode). The products of decomposition of
the oxygen include ozone. The corona discharge devices that were
first developed have been improved over the years. And now
commercially available corona discharge devices can generate a
pound of ozone from pure oxygen with as little as 3 kilowatt-hours
of energy. Furthermore, the corona discharge process can now
convert more than 10 percent of pure oxygen to ozone. Both the
energy efficiency and the ozone concentration are critical to the
economical production of ozone. In addition to these operating
characteristics, ozone generator equipment cost and maintenance are
important factors.
[0004] Although the corona discharge process has come to be the
main method for ozone production, it has its disadvantages and
limitations. First of all, relatively large electrode surface areas
are required for the corona discharge process. This causes corona
discharge reaction chambers to be relatively large and expensive.
This large size can also have a significant impact on the space
requirements within the user's process facility. Secondly, corona
discharge devices require periodic cleaning and replacement of
their corona discharge electrodes and insulators in order to
minimize system failures. This not only has a labor cost impact,
but also has an impact on the floor space needed for access to the
system for proper cleaning as well as an impact on the available up
time of these systems. Thirdly, corona discharge systems require
relatively sophisticated high voltage, high frequency pulsed power
supplies to operate. These systems are expensive, complicated and
require access to highly qualified technical staff for servicing.
And finally, the operating efficiency of the corona discharge
device is highly dependent on the availability of low temperature
cooling water. This means that in most locations a substantial cost
for water chillers must be included in the capital equipment and
operating budget for corona discharge systems. In addition, more
space, power, and maintenance are required to support the
chiller.
[0005] Alternative methods for the production of ozone have been
reviewed and some have been shown to be viable from the aspect of
overall efficiency of production. Steinberg, Beller, and Powell
have discussed the advantages of using chemonuclear reactors as an
efficient ozone production process. Unfortunately this process may
only be cost effective from a capital equipment standpoint for the
very largest of water treatment facilities. A number of studies
have been made evaluating ozone production rates using either gamma
or electron beam radiation. Although these studies have generally
shown production efficiencies that equal or exceed corona discharge
devices, the capital cost comparisons did not show any economic
advantages of these alternatives except for the very largest of
systems.
[0006] Several patents have been issued for electron beam devices
used for the generation of ozone. U.S. Pat. No. 3,883,413 to
Douglas-Hamilton (1975) discusses a pulsed discharge electron beam
device that generates ozone with the same efficiency that corona
discharge systems have today. However this system is not an
economical alternative because of its typical ozone concentration
of only 0.4%. This is well below the 10 to 15% ozone concentration
levels attainable with today's corona discharge systems. U.S. Pat.
No. 4,167,466 to Orr, Jr. et al. (1979) describes an electron beam
generator with much higher production efficiency. This device
requires as little as 0.26 kW-hours of energy to produce a pound of
ozone. The patent indicates that high efficiencies are attained by
moving oxygen past the beam at high velocities. However the ozone
concentrations produced are still less than 1 percent for a single
pass through. The patent does indicate much higher ozone production
concentrations are possible by repeatedly recycling the oxygen past
the beam. However there is no mention of how this can be
accomplished cost effectively. U.S. Pat. No. 5,756,054 to Wong et
al. (1998) describes an electron beam device that can be used to
generate ozone directly from liquid oxygen. This is supported by
earlier research that indicated generating ozone concentration
levels of up to 10% were generated by an electron beam in liquid
oxygen. However the energy dosage had to be applied slowly and the
oxygen had to be cryogenically cooled to be maintained in a liquid
state. U.S. Pat. No. 5,756,054 discusses an approach that uses
cryogenic cooling to separate the ozone from the oxygen. In this
way the oxygen not converted to ozone could continue to be
processed to maximize ozone production. However it does not address
the economics of this process in order to evaluate its cost
relative to its benefit.
[0007] In summary, a number of corona discharge devices have been
used for the production of ozone, but nevertheless they all suffer
from a number of disadvantages:
[0008] (a) They are large and require considerable space within a
facility
[0009] (b) They require the use of expensive pulsed or high
frequency power supplies
[0010] (c) They require periodic cleaning and other maintenance to
function effectively
[0011] (d) They require water chillers to operate at high
efficiencies.
[0012] In addition, electron beam generators have been proposed as
alternative ozone generating devices, however they also have a
number of disadvantages:
[0013] (a) Proposed electron beam generators are expensive to
manufacture because of their complex configuration and beam
focusing requirements.
[0014] (b) Their unidirectional or bi-directional beam structure
does not allow the system to have the compactness desired for
processing systems.
[0015] (c) Currently proposed electron beam generators have thus
far only generated low concentrations of ozone which may, to some
extent be due to recycling limitations.
[0016] (d) Additional apparatus proposed for increasing ozone
concentrations involving multiple recycling of the oxygen or
refrigeration to precipitate ozone are relatively expensive and
complicated processes.
[0017] A number of patents have been issued for the decomposition
of sulfur dioxide and other pollutants using electron beam
irradiation. The most important difficulties to overcome for
effective irradiation have been penetration of the medium to be
processed and spreading the electron beam to effectively process
large waste streams. Many innovative techniques have been employed
in attempts to overcome these difficulties. For example in U.S.
Pat. No. 3,891,855 to Offermann (1975) and U.S. Pat. No. 4,173,719
to Tauber et al. (1979) the process fluid stream is narrowed to
allow penetration with a lower energy beam. However converting the
fluid stream to a wide, narrow channel can be expensive and cause
substantial flow losses and process complications. Other attempts
have been made including processing contaminated fluids in the
vapor phase as described U.S. Pat. No. 5,319,211 to Matthews et al.
(1994). Although penetration of the fluid in the gaseous state is
easier, it still requires a complicated flow channel. Furthermore,
all electron beam process techniques thus far have been based on
treating contaminated fluids where the contaminant is mixed
throughout. No effort is made to differentiate and separate the
components for preferential processing of only the
contaminants.
[0018] In summary, electron beam generators have been proposed, and
to some extent, used for the removal of sulfur dioxide and other
pollutants in the past, however they all suffer from the following
disadvantages:
[0019] (a) Because of their limited penetration, particularly in
denser fluids, the electron beam energy levels must be relatively
high which has a direct relationship to their capital cost.
[0020] (b) Existing electron beam processors must penetrate and
irradiate the entire fluid volume even though the contaminant may
be only a small fraction of this volume.
[0021] (c) In order to uniformly irradiate fluids with a
unidirectional beam, the fluid flow profile must be very flat and
wide, which may be expensive to construct for large effluent
streams.
[0022] (d) The high energy and unidirectional nature of existing
electron beam systems necessitates substantial radiation shielding
requirements for safety.
SUMMARY OF THE INVENTION
[0023] The invention includes apparatus and methods for the
production of ozone (O.sub.3) and decomposition of contaminants,
specifically to a method of using density differences in fluids
combined with a cylindrically configured irradiation apparatus for
improved production of ozone from air or oxygen and for
decontamination. Ozone is used as a treatment for drinking water,
wastewater, and related applications where it interacts with
organic impurities to implement disinfection. Decontamination
applications include removal of gaseous pollutants such as sulfur
dioxide from effluent gas and volatile organic compound
decomposition in water, wastewater, air and other gases.
[0024] A method of and apparatus for generating ozone from oxygen
or air with irradiation such as from an electron beam. A means for
cooling and preferentially positioning oxygen or air to increase
ozone yield efficiency and concentration is employed. The disclosed
method and apparatus may also be used for other process
applications including waste gas and wastewater
decontamination.
[0025] Accordingly, several objects and advantages of the present
invention for the application of ozone generation are:
[0026] (a) to provide a method of ozone generation that
preferentially positions the oxygen so that much higher
concentrations of ozone can be produced than is possible with the
existing technology.
[0027] (b) to provide a method of ozone generation that is capable
of producing ozone at higher energy efficiencies than is possible
with the existing technology.
[0028] (c) to provide an ozone generator that is compact and
minimizes the space required within a facility.
[0029] (d) to provide an ozone generator that uses a simple direct
current power supply instead of the pulsed power or high frequency
type of device currently used in existing ozone generators.
[0030] (e) to provide an ozone generator of which the reaction
chamber has virtually no cleaning or maintenance requirements.
[0031] (f) to provide an ozone generator that operates effectively
without the need for a water chilling device.
[0032] (g) to provide an electron beam type ozone generator that
does not require the complicated beam focusing systems typically
used for unidirectional beam generating devices.
[0033] (h) to provide an electron beam type ozone generator that
can use a simple, low cost cylindrical chamber geometry similar to
standard radio tubes.
[0034] A further advantage is to provide an ozone generator which
will be able to produce ozone at consistent production levels
without the need to perform special tuning of the power supply and
reaction chamber as is typically the case for corona discharge
devices. Still further objects and advantages will become apparent
from a consideration of the ensuing description and drawings.
[0035] Regarding embodiments of the invention adapted for use in
removing gaseous pollutants, several objects and advantages of the
present invention for the destruction of sulfur dioxide and other
pollutants and decontamination of fluids are:
[0036] (a) To provide a method that can preferentially position
sulfur dioxide and other contaminants close to the irradiation
source causing them to be decontaminated with a much lower beam
energy.
[0037] (b) To provide a method that can preferentially position
contaminants close to the irradiation source therefore reducing the
volume of fluid that must be exposed which reduces the total power
needed for contaminant removal or treatment.
[0038] (c) to provide an electron beam irradiator that does not
require the complicated beam focusing systems typically used for
unidirectional beam generating devices.
[0039] (d) to provide an electron beam irradiator that can use a
simple, low cost cylindrical chamber geometry similar to standard
radio tubes.
[0040] A further advantage is that because of its low cost
configuration, the current invention can be applied to a wider
range of pollution treatment applications where irradiation was
previously too expensive.
DRAWING FIGURES
[0041] In the drawings, closely related figures have the same
number but different alphabetic suffixes.
[0042] FIG. 1 shows an isometric drawing of an ozone generator
operating system.
[0043] FIG. 2 shows an assembly of an ozone generator chamber with
a section removed to illustrate the interior components.
[0044] FIG. 3 shows a cross-section of an ozone generator chamber
with a depiction of the oxygen conversion to ozone.
[0045] FIG. 4 shows a cross-section of a fluid treatment device
with a depiction of the pollutant decomposition.
1 Reference Numerals in Drawings: 10 ozone generator assembly 12
electron gun mounting plate 14 high voltage insulator bushing 16
electron gun cathode connection 18 mounting flange 20 liquid
cooling chamber 22 cathode emitter 24 electron beam window 26 ozone
reaction chamber 28 spiral vane 30 mounting base 32 cooling liquid
inlet port 34 oxygen inlet port 38 electron gun power supply 40
vacuum pumping system
DETAILED DESCRIPTION
Description--FIGS. 1 to 4
[0046] A typical embodiment of an ozone generator of the present
invention is illustrated in FIG. 2 (isometric view). The ozone
generator assembly 10 has an electron gun mounted in one end of the
assembly that is comprised of the electron gun mounting plate 12,
high voltage insulator bushing 14, electron gun cathode connection,
and a cathode emitter 16. The electron gun cathode emitter 16 is
enclosed in a vacuum by the electron beam window 24, and at the
ends by the ozone reaction chamber 26. Typically the electron beam
window is constructed of thin titanium foil or metallized plastic
film. The electron beam window 24 is held in position by soldering
or otherwise bonding the window to the spiral vane 28. It lies in
an annular space between the electron beam window 24 and the outer
wall of the ozone reaction chamber 26. The liquid cooling chamber
20 encloses the ozone reaction chamber 26 and creates an annular
cooling passage to cool the ozone reaction chamber 26. The mounting
flange 18 and mounting base 30 provide end closures for the vacuum
space inside the electron beam window 24 and the liquid cooling
chamber 20.
[0047] The entire ozone generator assembly 10 is constructed in a
cylindrical geometry to minimize its volume and simplify the
construction of the device as well as for functional reasons
explained below. The cylindrical construction of the cathode
emitter and vacuum enclosure is based on well established standard
vacuum tube design. The principal difference is that instead of
absorbing the current into the anode such as is done with a
standard vacuum tube, the current is transmitted through the
cylindrical electron beam window 24 into the oxygen gas or other
processed fluids outside the window. In one embodiment the cathode
emitter 22 is constructed of a cylindrical array of thoriated
titanium oxide filaments. Another embodiment consists of an oxide
coated cylindrical cathode or cylindrical dispenser cathode. All of
these possible embodiments are economic alternatives for radially
emitting the electron beam. Typically the cathode emitter diameter
is proportional to type of cathode used and the current that must
be emitted. In this embodiment the diameter can range from less
than 25 millimeters to several hundred millimeters.
[0048] The cathode emitter 22 and electron beam window 24 create
anode to cathode accelerating space. A negative high voltage in the
range of less than 100,000 volts to several hundred thousand volts
with respect to ground at the anode is applied to the cathode
emitter 22. The gap spacing for electron guns in the voltage range
indicated may be less than 25 millimeters to well over 100
millimeters. However because of the superior voltage hold-off
characteristics of the coaxial geometry, the gap spacing
requirement and consequently the vacuum tube diameter is minimized.
The vacuum tube anode diameter is limited mainly by the ability to
dissipate the heat deposited in the electron beam window 24. As
will be described later, the window is well cooled by rapid flowing
process fluid. And this allows much higher energy output per unit
area than is possible with corona discharge devices.
[0049] An embodiment of this device includes a bias grid
surrounding the emitter to regulate the emitted current. The grid
bias voltage is generally provided by an additional power supply
through the same high voltage insulator bushing 14 that provides
the high voltage power for the cathode emitter 22. High voltage
cables normally transmit the high voltage power for the cathode
emitter 22. In one embodiment of the invention, the high voltage
cable is eliminated by connecting the electron gun cathode
connection 16 directly to the electron gun power supply 38 (FIG.
1).
[0050] One embodiment of this invention is the unique combined
construction of the high vacuum enclosed space and electron beam
window 24. Typical electron gun systems incorporate a high vacuum
chamber constructed of stainless steel with a beam window mounted
in one side of the chamber. This typical construction is
complicated and expensive. One of the embodiments of this invention
is that the electron beam window 24 is cylindrical in shape and
forms the entire vacuum space by attaching it to the spiral vane
28. This spiral vane 28 serves several purposes and one of them is
to form the cylindrical support for the electron beam window. For
fluids that create relatively high pressures on the electron beam
window 24, a ring support is placed inside the enclosed vacuum
space to internally support the window. To maximize the electron
beam transmission into the oxygen or fluid the ring support is
formed in the electron beam shadow of the spiral vane 28.
[0051] The spiral vane 28 is constructed in a spiral pattern and
creates the oxygen or fluid path that is to be processed. The width
of the spiral vane is dependent on the heat transfer required to
absorb the beam energy and is typically 2 to 20 millimeters wide.
The depth of the spiral vane 28 is established by the energy of the
beam and the density of the fluid being processed. For liquids this
depth may be as small as 0.25 millimeter and for gases the depth
may be in excess of 25 millimeters. An important embodiment of this
invention is that the depth of the vanes in the reaction chamber is
established to insure that most of the beam will be absorbed by the
fluid. Very little of the beam should strike the reaction chamber
wall in order to maximize ozone production as defined in the
operation. Typically the reaction chamber 26 and the spiral vane 28
are constructed of high thermal conductivity metal such as copper
or aluminum for more efficient heat transfer. A high conductivity
coating such as silver is typically used to protect the surface
from corrosion or oxidation without compromising the chamber
conductivity.
[0052] From the description above, a number of advantages of this
ozone generator and fluid processor become evident:
[0053] (a) Unlike currently designed ozone generators based on
corona discharge, the cylindrical construction of this invention is
simple and economical to manufacture.
[0054] (b) Electron beam generators have a much higher energy
output per unit of surface area, which allows this device to be
much more compact than conventional ozone generators.
[0055] (c) The power supply for this device can be a standard high
voltage direct current unit instead of a pulsed power device. And
if pulsed power is desired a relatively simple grid supply can be
used to turn the electron beam on and off.
[0056] (d) Unlike corona discharge ozone generators, the vacuum
tube type of construction has a long history of reliable
performance requiring very little maintenance.
[0057] (e) Because of the substantially smaller size of this device
compared to a corona discharge type system, it is much easier to
provide maintenance without the need for special equipment.
[0058] (f) By incorporating the centrifuge effect into the process,
my generator can selectively direct its energy at oxygen instead of
at previously generated ozone leading to the potential to produce
much higher concentrations of ozone.
[0059] (g) This same centrifuge effect allows selective irradiation
which provides the capability to use lower energy, lower capacity
electron beams for decontamination than conventional
irradiators.
Operation--FIGS. 1, 2, 3, 4
[0060] In the preferred embodiment of the ozone generator and fluid
processor 10 oxygen gas is delivered to the oxygen inlet port 34.
The oxygen is typically transferred from an oxygen source such as a
cryogenic vessel filled with liquid oxygen. The pressure required
to transfer the liquid oxygen is typically generated by the
pressure setting on the cryogenic vessel. Once the oxygen enters
the oxygen inlet port 34 it then enters the cavity formed by the
spiral vane 28 inside the reaction chamber 26 where the oxygen
follows in a spiral pattern. An electron beam is emitted from the
cathode emitter 22 and is accelerated radially outward from its
center by a negative high voltage. The cathode voltage is in the
order of 100,000 volts with respect to the outer wall or window
where the electron beam exits. This radially directed electron beam
has sufficient energy so that the majority of the beam penetrates
the cylindrical electron beam window 24 and is deposited into the
oxygen gas that is spiraling around the exterior of this window.
The electron beam continues to traverse through the oxygen or other
fluid and dissipates its energy therein. The electron beam that is
deposited into the oxygen has sufficient energy to convert some
proportion of it to ozone. Once the ozone and remaining oxygen
reach the end of the spiral vane, the two fluids exit the reaction
chamber and are transferred to the process requiring the ozone.
[0061] In order to produce ozone, tremendous amounts of heat must
be deposited into the oxygen. Without the benefit of cooling, the
overall temperature of the gas could exceed 1000 degrees Celsius.
This excessive temperature would then cause decomposition of the
ozone produced leading to limited ozone production. Efficient
cooling of the gas is required to prevent this decomposition. The
spiral rib pattern of the reaction chamber combined with high
velocity flow of the fluid provides the cooling necessary to
significantly reduce decomposition of the ozone generated. This
flow is typically in the 1000 to 3000 meters per minute for
efficient cooling. The heat absorbed by the spiral ribs is
transferred into the cooling water or fluid flowing on the exterior
of the reaction chamber rib structure.
[0062] This high-velocity cooling requirement also creates the
added benefit of higher ozone energy conversion efficiency as
mentioned in the earlier patent.
[0063] The most important characteristic of this method of ozone
generation is that the spiral gas flow creates a centrifuge effect.
This centrifuge effect causes the oxygen and ozone gases to
separate with the newly formed higher density ozone gas moving to
the outer edge of the spiral cavity. This separation caused by
centrifugal force allows the oxygen to continue to be positioned
closest to the incoming electron beam. FIG. 3 shows how the ozone
and oxygen move through the generator. The resultant benefit is
that the oxygen gas absorbs most of the beam and relatively small
amounts penetrate the layer of oxygen gas to strike the outer layer
of ozone just produced. This combined effect of high velocity flow
and centrifugal force created with the spiral motion creates the
potential for unprecedented concentrations of ozone while still
maintaining high-energy efficiency ozone production.
[0064] In summary, the key to high efficiency ozone production by
electron beam is high velocity oxygen flow past the beam. And the
key to producing high concentrations of ozone is recycling the
oxygen while separating the generated ozone to prevent its
decomposition. The method of spiral gas flow of this invention
allows these key events to occur simultaneously and also is the key
to the removal of high levels of generated heat. And the unique
cylindrical radial electron beam pattern with its inherent compact
beam geometry facilitates the employment of this unique ozone
production process.
[0065] This same method can be employed for processing other fluids
as well. The key is that the fluids that require processing must
have a significant density difference than the other fluids in the
stream. There are some differences in operation, but the principles
are the same. For example, sulfur dioxide, (SO.sub.2) has a
significantly higher density than the other gases in a smokestack
effluent stream. In this instance, since the gas to be irradiated
is denser than the other gases, the electron beam geometry has to
be radiated towards the center of the axis instead of outward.
Another major difference is that the heat dissipation requirements
are much lower than for ozone production. Therefore there may not
be a requirement for facility cooling.
[0066] FIG. 4 shows an embodiment of this invention to decompose a
pollutant. In this example it is assumed that the pollutant to be
decomposed is denser than the other gases in the flow stream, and
that no additional cooling is required. In this embodiment the
cathode is shown radiating inward. The pollutant as well as the
other gases are fed into the spiral vane chamber 26 which in this
case shows the chamber wall inboard. The electron beam window 24
attaches on the outer edge of the spiral vane 28. As the gas or
fluid flows in the spiral pattern, centripetal force causes the
denser pollutant to flow to the outer wall, which is in this case,
is the electron beam window 24. The inward radiating electron beam
therefore is mainly absorbed in the pollutant causing it to
decompose or otherwise be altered to an acceptable state. This
process substantially reduces the power required because a much
smaller percentage of fluid is processed, and the beam penetration
requirements are much lower.
[0067] The inward radiating electron beam generator configuration
shown in FIG. 4 can have other variations. For example for stack
gases where it is desirable to minimize flow interruptions and
discontinuities, a spiral vane can be mounted axially in the beam
path so that the gas flows directly out of its pipe, through the
spiral vane, and back into pipe of the same diameter. FIG. 5 shows
an example of this kind of device.
[0068] In summary, the method of spiraling the fluid to create the
centrifuge action, coupled with the unique circular geometry of the
irradiator that allows radiation inward as well as outward provides
a unique alternative for cost effective processing with electron
beam. By concentrating and isolating the fluid to be treated, a
substantial reduction in both power requirements and capital
equipment requirements is attained.
[0069] Accordingly, the reader will see that the ozone generator of
this invention can be used to produce ozone efficiently and
economically. And because of the processes incorporated and its
unique geometry it has the potential to attain much higher ozone
concentrations more efficiently than existing ozone generating
devices. These advantages mean that both less power and less oxygen
are required than corona discharge devices to generate the same
quantities of ozone. As a processor for contaminated fluids the
invention has the further advantages that it only requires a
fraction of the voltage that conventional electron beam processors
require. And since it does not need to process the entire fluid
stream, it requires only a fraction of the throughput normally
required for such a device. Furthermore the ozone generator and
fluid processor apparatus has the following additional
advantages:
[0070] Because of its simple construction, it can be manufactured
at a considerably lower cost than corona discharge ozone generating
devices.
[0071] It is much smaller than existing corona discharge generating
devices and can therefore be more easily installed in limited
spaces.
[0072] It is powered by much simpler dc power supplies that are
less expensive to build than medium to high frequency or pulsed
power supplies that are now used for existing ozone generators.
[0073] It requires little or no cleaning and maintenance because
there are no corona discharge components that wear and must be
periodically cleaned and replaced.
[0074] Unlike existing ozone generators, there is no requirement
for expensive chilled water equipment that will take up valuable
plant operating space to support efficient production of ozone.
[0075] It allows the use of standard vacuum tube cylindrical
geometry, a much lower cost construction than unidirectional
electron beam generating devices.
[0076] Although the description above has been directed at
describing particular embodiments of the method and device in
accordance with the patent requirements, it should not be construed
as limiting the scope of the invention but as merely providing
illustrations of some of the presently preferred embodiments of
this invention. For example, a pulsed power high voltage supply can
be used instead of a dc supply. The cathode emitter can be square
or rectangular instead of cylindrical. The high voltage insulator
bushing can be tapered in a different direction than what is shown.
The spiral vane can be a group of vanes in either a spiral pattern
or in a cylindrical pattern that move the fluid in parallel with
one another around the electron beam window. The oxygen can be
directed into any flow pattern that achieves the preferred
orientation of the oxygen closest to the beam and the ozone
farthest from the beam. For fluid process streams where the
pollutants to be treated are denser than the fluid, the irradiation
is directed inwards as shown in FIG. 4.
[0077] It should also be noted that this electron beam device can
be used for a number of other applications where the benefit of
electron beam processing combined with the centrifuge effect
facilitate the preferential processing of dissimilar density
materials. As previously mentioned, the dissimilar densities of
exhaust or smokestack gases can allow the different density gases
to be preferentially processed by the electron beam. For example,
for denser gases such as sulfur dioxide, the centrifuge effect of
spiraling the gas causes it to move to the outermost section of the
reaction chamber. This then requires the irradiation device to be
directed inward to decompose the sulfur dioxide gas as shown in
FIGS. 4 and 5.
[0078] As also mentioned, this process is also applicable to
liquids such as water and other fluids which may contain
contaminants that are at different densities than the main fluid
stream. One specific application is for irradiating suspended
solids in a liquid. By using the centrifuge effect caused by
spiraling the fluid with its suspended solids, the solids which are
denser move outward in the spiraled fluid stream and are therefore
irradiated by a process beam such as shown in FIG. 4.
[0079] Another application that this can be used for is radiation
curing. For example, polymers that are to be applied are often
transferred in a solvent that is of lower density. The process of
spiraling the polymer that must be cured past an irradiator prior
to its being applied to a substrate may save considerable curing
costs. In this case since the polymer is denser than the solvent
carrying it, it is forced against the outside wall and is therefore
preferentially treated by an inward electron beam device such as
depicted in FIG.4.
[0080] Another application is for fluid sterilization when there is
a mixture of fluids that have significantly different densities. If
only one of the fluids requires irradiation for pasteurization or
sterilization, this component can be preferentially positioned to
the outer wall if it is denser whereby the device in FIG. 4 would
be applicable. If the fluid to be treated was a lower density than
the other fluid or fluids, this lower density material would
migrate to the inner wall of the spiral chamber and would therefore
be irradiated with an outwardly directed beam as shown in FIG.
3.
[0081] Food pasteurization with an irradiation source is also an
application for which this device can be used. For example if a
food component that needs to be treated is of a different density
than other components within the food mixture, the particular
component requiring treatment can be separated using the centrifuge
effect so that it can be positioned closest to the irradiation
source. If it is denser than the rest of the food ingredients it
will migrate towards the outermost perimeter of the spiral path and
will thus be irradiated with the inward pattern beam as shown in
FIG. 4. If it is lighter than the rest of the food components it
will migrate towards the innermost area of the spiral path so that
it can be irradiated with the outwardly oriented beam.
[0082] There are many other applications of how this process and
device can be used that are not enumerated here. Thus the scope of
the invention should be determined by the appended claims and their
legal equivalents, rather than by only the examples given.
* * * * *