U.S. patent application number 11/281996 was filed with the patent office on 2006-08-03 for novel method of dosing liquids with pressurized ozone.
Invention is credited to Steven A. Fisher.
Application Number | 20060168999 11/281996 |
Document ID | / |
Family ID | 36793401 |
Filed Date | 2006-08-03 |
United States Patent
Application |
20060168999 |
Kind Code |
A1 |
Fisher; Steven A. |
August 3, 2006 |
Novel method of dosing liquids with pressurized ozone
Abstract
Methods of treating and sanitizing foods and other targeted
objects, including the use of ozone and a method for providing a
liquid dosed with pressurized ozone. The ozonated liquid of the
invention is particularly useful for treating food products, food
storage, and food transportation devices as well as treating water,
or other target objects. Included is a method or pressurizing an
ozone-containing stream without destroying the ozone or
contaminating the stream with oil or water. The pressurized
ozone-containing stream is then used to dose a liquid, which in
turn is used to sanitize or treat a target object.
Inventors: |
Fisher; Steven A.;
(Brookfield, IL) |
Correspondence
Address: |
AIR LIQUIDE
2700 POST OAK BOULEVARD, SUITE 1800
HOUSTON
TX
77056
US
|
Family ID: |
36793401 |
Appl. No.: |
11/281996 |
Filed: |
November 17, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11145137 |
Jun 3, 2005 |
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11281996 |
Nov 17, 2005 |
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10632232 |
Jul 31, 2003 |
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11145137 |
Jun 3, 2005 |
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60404635 |
Aug 20, 2002 |
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60459398 |
Apr 1, 2003 |
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60638020 |
Dec 21, 2004 |
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Current U.S.
Class: |
62/606 ;
417/65 |
Current CPC
Class: |
F17C 2227/0192 20130101;
F17C 2221/01 20130101; F17C 2225/0123 20130101; F17C 2225/035
20130101; F17C 5/06 20130101; F17C 2205/0138 20130101; A23V 2200/10
20130101; A23V 2250/128 20130101; A23V 2002/00 20130101; F17C
2227/0178 20130101; A23L 3/358 20130101; A23V 2002/00 20130101;
F17C 2223/033 20130101; A23L 3/3409 20130101; F17C 9/00 20130101;
F17C 2270/05 20130101; F17C 2265/025 20130101; F17C 2223/043
20130101; F17C 2223/0123 20130101 |
Class at
Publication: |
062/606 ;
417/065 |
International
Class: |
E21B 43/12 20060101
E21B043/12; F25J 1/00 20060101 F25J001/00 |
Claims
1. A method of pressurizing ozone comprising the steps of: a)
providing an ozone source and an ozone pressurization system; b)
feeding an ozone-containing gas from said ozone source to said
ozone pressurization system to establish a first pressure; c)
pressurizing said ozone pressurization system to a second pressure
by feeding a pressurization gas to said ozone pressurization system
to form a pressurized ozone-containing gas; and d) withdrawing said
pressurized ozone-containing gas from said ozone pressurization
system.
2. The method of claim 1, wherein said pressurized ozone-containing
stream is substantially absent oil and water.
3. The method of claim 1, wherein: a) said ozone pressurization
system comprises a pressurization vessel; b) said pressurization
gas is fed into the lower portion of said pressurization vessel;
and c) said pressurized ozone-containing gas is withdrawn from the
upper portion of said pressurization vessel.
4. The method of claim 1, wherein: a) said ozone pressurization
system comprises a plurality of pressurization vessels comprising a
first pressurization vessel and a last pressurization vessel; b)
said plurality of pressurization vessels are fluidly connected in
series; and c) wherein said pressurizing gas is fed exclusively to
said first pressurization vessel.
5. The method of claim 4, wherein said pressurizing step further
comprises the steps of: a) withdrawing a pressurized gas mixture
from said first pressurization vessel; b) feeding said pressurized
gas mixture to said last pressurization vessel, wherein pressurized
ozone-containing gas is withdrawn from said last pressurization
vessel.
6. The method of claim 5, wherein: a) said pressurization gas is
fed into a lower portion of said first pressurization vessel; b)
said pressurized gas mixture is withdrawn from an upper portion of
said first pressurization vessel; c) said pressurized gas mixture
is fed into a lower portion of said last pressurization vessel; and
d) said pressurized ozone-containing gas is withdrawn from an upper
portion of said last pressurization vessel.
7. The method of claim 4, wherein said pressurizing step further
comprises the steps of: a) withdrawing a pressurized gas mixture
from said first pressurization vessel; b) feeding said pressurized
gas mixture to a successive pressurization vessel; and c)
transferring said pressurized gas mixture from said successive
pressurization vessel to said last pressurization vessel, wherein
pressurized ozone-containing gas is withdrawn from said last
pressurization vessel.
8. The method of claim 7, wherein: a) said pressurization gas is
fed into a lower portion of said first pressurization vessel to
form a pressurized gas mixture; b) said pressurized gas mixture is
withdrawn from an upper portion of said first pressurization
vessel; c) said pressurized gas mixture is fed into a lower portion
of said successive pressurization vessel; d) said pressurized gas
is withdrawn from an upper portion of said successive
pressurization vessel; and e) said pressurized gas mixture is
transferred into a lower portion of said last pressurization
vessel.
9. The method of claim 1, wherein said pressurization gas is a dry
gas.
10. The method of claim 9, wherein said dry gas is CO.sub.2.
11. The method of claim 1, wherein said second pressure is greater
than about 150 psig.
12. The method of claim 11, wherein said first pressure is less
than about 50 psig.
13. A method of supplying an ozonated liquid comprising the steps
of: a) providing an ozone source and an ozone pressurization
system; b) feeding an ozone-containing gas from said ozone source
to said ozone pressurization system to establish a first pressure;
c) pressurizing said ozone pressurization system by feeding a
pressurization gas into said ozone pressurization system, wherein
said pressurizing gas raises the pressure of said ozone-containing
gas to a second pressure to form a pressurized ozone-containing
gas; d) providing a liquefied dry gas; e) transferring said
liquefied dry gas to an expansion vessel; f) sparging said
pressurized ozone-containing gas through said liquefied dry gas in
said expansion tank to form an ozonated liquefied dry gas; and g)
withdrawing said ozonated liquefied dry gas from said expansion
vessel.
14. The method of claim 13, further comprising the steps of
withdrawing a vent gas from said expansion tank and recycling said
vent gas to a liquefied dry gas storage vessel.
15. The method of claim 13, wherein said sparging occurs
substantially continuously.
16. The method of claim 13, wherein said pressurizing step further
comprises the steps of: a) providing a plurality of pressurization
vessels fluidly connected in series in said pressurization system;
b) feeding said pressurizing gas exclusively to a first
pressurization vessel in said pressurization system; c) withdrawing
a pressurized gas mixture from said first pressurization vessel; d)
feeding said pressurized gas mixture to said last pressurization
vessel, wherein pressurized ozone-containing gas is withdrawn from
said last pressurization vessel.
17. The method of claim 13, wherein said pressurized
ozone-containing gas is substantially absent water and oil.
18. A device for supplying a pressurized ozone-containing gas
comprising: a) an ozone pressurization system comprising: i) a
first pressurization vessel; ii) a last pressurization vessel; iii)
a pressurization inlet located on a lower portion of said first
pressurization vessel; iv) a means of fluidly connecting the upper
portion of said first pressurization vessel to a lower portion of
said last pressurization vessel; and v) a pressurized ozone outlet
located on an upper portion of said last pressurization vessel; b)
an ozone-containing feedstream in fluid communication with said
first pressurization vessel; c) a pressurization gas feedstream in
fluid communication with said pressurization inlet; and d) a
pressurized ozone-containing stream in fluid communication with
said pressurized ozone outlet.
19. The device of claim 18, further comprising a successive
pressurization vessel, wherein: a) an upper portion of said first
pressurization vessel is fluidly connected to a lower portion of
said successive pressurization vessel; and b) an upper portion of
said successive pressurization vessel is fluidly connected to a
lower portion of said last pressurization vessel.
20. The device of claim 19, wherein said successive pressurization
vessel comprises at least two further successive pressurization
vessels fluidly connected in series.
21. The device of claim 18, wherein said pressurization gas
feedstream comprises a dry gas.
22. The device of claim 21, wherein said dry gas is CO.sub.2.
23. A method of supplying an ozonated liquid comprising the steps
of: a) providing an ozone source and an ozone pressurization
system; b) feeding an ozone-containing gas from said ozone source
to said ozone pressurization system to establish a first pressure;
c) pressurizing said ozone pressurization system by feeding a
pressurization gas into said ozone pressurization system, wherein
said pressurizing gas raises the pressure of said ozone-containing
gas to a second pressure to form a pressurized ozone-containing
gas; d) providing a liquid in a pressure vessel; e) sparging said
pressurized ozone-containing gas through said liquid in said
pressure vessel to form an ozonated liquid; and g) withdrawing said
ozonated liquid from said pressure vessel.
24. The method of claim 23, wherein a pressure in said pressure
vessel is greater than about 150 psig during said sparging
step.
25. The method of claim 23, wherein a pressure in said pressure
vessel is greater than about 200 psig during said sparging
step.
26. The method of claim 23, wherein a pressure in said pressure
vessel is greater than about 300 psig during said sparging
step.
27. The method of claim 23, wherein said sparging occurs
substantially continuously.
28. The method of claim 23, wherein said pressurizing step further
comprises the steps of: a) providing a plurality of pressurization
vessels fluidly connected in series in said pressurization system;
b) feeding said pressurizing gas exclusively to a first
pressurization vessel in said pressurization system; c) withdrawing
a pressurized gas mixture from said first pressurization vessel;
and d) feeding said pressurized gas mixture to said last
pressurization vessel, wherein pressurized ozone-containing gas is
withdrawn from said last pressurization vessel.
29. The method of claim 23, wherein said pressurized
ozone-containing gas is substantially absent water and oil.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of and claims
priority to U.S. application Ser. No. 11/145,137, filed Jun. 3,
2005, entitled, "Novel Biological Treating Agent," which is a
continuation-in-part of and claims priority to U.S. application
Ser. No. 10/632,232, filed Jul. 31, 2003, which is a
non-provisional application claiming priority of U.S. Provisional
application 60/404,635, filed Aug. 20, 2002, and U.S. Provisional
application 60/459,398, filed Apr. 1, 2003. This application also
claims priority to U.S. Provisional application 60/638,020, filed
Dec. 21, 2004. The entire contents of these applications are hereby
incorporated by reference.
BACKGROUND
[0002] Treating and sanitation of food, equipment, pharmaceutical
products, and even water to reduce undesirable biological
microorganisms is important to the protection of public health. For
example, food can be damaged by microbes, spores, insects, and
other similar sources. Each year, economic losses of food and labor
due to damage from such sources is more than $100 billion.
Currently, food items are preserved using a variety of methods,
including refrigeration, fumigation with toxic chemicals,
irradiation, biological control, heat exposure, and controlled
atmosphere storage (a fruit industry technique that involves
modifying the concentration of gases naturally present in the
air).
[0003] The primary problem regarding food spoilage in public health
is microbial growth. If pathogenic microorganisms are present, then
growth can potentially lead to food-borne outbreaks and significant
economic losses. Food safety concerns have been brought to the
consumers' attention since the early part of the 20.sup.th century
and those concerns have become even stronger today. Outbreaks from
Salmonella and E. coli have increased the focus on food safety,
including from a regulatory perspective. A study completed by the
Centers for Disease Control and Prevention (CDC) estimated that
food-borne diseases cause approximately 76 million illnesses,
325,000 hospitalizations, and 5,000 deaths annually in the US.
Those numbers reveal the dramatic need for effective means of
handling food products in order to ensure food safety.
[0004] Effective sanitation of food or other items depends on the
combination of what is to be sanitized and the sanitation process
type. Not all of the currently available technologies can deliver
an effective reduction of microorganisms and at the same time
prevent product or environmental degradation. It is well known in
the art to cool products, such as foods, during processing with
some type of refrigerant to slow down the growth of unwanted
microbes and enzymatic reactions in foods. For instance, the shelf
life and quality of food products are improved by processing,
transporting, and storing under refrigerated conditions.
[0005] Cooling agents, such as water ice, dry ice, carbon dioxide,
or nitrogen, are liquid or solid agents that can be used as an
expendable refrigerant. In food processing applications, liquids,
such as nitrogen, are used to cool and inert the atmosphere during
food processing or storage.
[0006] While refrigeration can retard microbial growth, such
treatment does not necessarily kill bacteria. Accordingly,
microorganisms can still survive through refrigeration, and worse,
some microorganisms can still grow and produce harmful substances
during refrigerated storage. Furthermore, it is possible that the
refrigerant used to cool a target item or food product can itself
be contaminated with pathogenic microorganisms, thus contaminating
the target item or food product.
[0007] Biocidal agents are used to sanitize equipment, provide
antiseptic environments, treat water, and sanitize foods. The
reaction of biocidal agents with microbial cell structures is often
irreversible; therefore the cells either become attenuated or
die.
[0008] One biocidal agent commonly used in the industry is ozone.
However, ozone is very unstable, and therefore, must be produced at
the location of consumption. Production of ozone requires
specialized equipment and involves safety issues due to handling of
the equipment and feedstock, such as pure oxygen. After the ozone
is produced, it must be delivered in some form to the target item
as a sanitizer. Ozone is often dissolved or absorbed in water as a
mechanism to deliver the unstable ozone to a target item. However,
ozone has poor solubility in water. Mixtures of ozone and water
typically contain less than about 20 ppm by weight (ppmwt) ozone.
As a result, large quantities of water relative to the ozone are
required if water is used as a delivery agent. Furthermore, because
of the large quantities of water required, the ozone and water
cannot be pre-mixed and transported to site. Thus, ozone and water
must be mixed on site.
[0009] Another problem with ozone is the difficulty in compressing
an ozone-containing stream. There are no commercial processes known
to one of ordinary skill in the art that are capable of delivering
ozone at high pressures. Ozone generating equipment known in the
art typically produces an ozone-containing gas stream at fairly low
pressures. These ozone generators are typically limited to
producing a stream with a pressure of less than about 25 psig.
Conventional mechanical compression cannot be used to compress
ozone because the unstable ozone molecule is destroyed in
conventional compressors. Oil-lubricated or water ring compression
can be used to compress a stream containing ozone up to 150 psig;
however, these compressors inherently contaminate the ozone stream
with oil or water respectively. Therefore, the prior art fails to
provide a method to compress the ozone to pressures above about 25
psig without contaminating the ozone stream with some level of oil
or water. Furthermore, the prior art fails to provide any method to
successfully compress an ozone stream to pressures of greater than
about 150 psig without destroying the ozone.
[0010] It is desirable to pressurize ozone to be used to sanitize
equipment or devices and process foods. It is particularly
desirable to be able to provide ozone in a pressurized stream at
pressures above 150 psig without contaminating the ozone with oil
or water. Further yet, it is desirable to pressurize ozone and feed
it into a liquid, so that it is absorbed under pressure into the
liquid and the liquid can them be used to treat of sanitize devices
or food products.
SUMMARY
[0011] The current invention fulfills the need to provide a process
to pressurize an ozone-containing stream without destroying the
ozone or contaminating the ozone-containing stream with oil or
water. It is desirable to be able to provide a pressurized
ozone-containing stream that is substantially free of oil and
moisture. It is also desirable to the ozone-containing stream at
pressures above 150 psig. It further desirable to pressurize ozone
and feed it into a liquid, so that it is absorbed under pressure
into the liquid.
[0012] The current invention pressurizes ozone by feeding an
ozone-containing source to an ozone pressurization system to
establish a first pressure followed by pressurizing the ozone
pressurization system. The ozone pressurization system is
pressurized by feeding a pressurization gas to the ozone
pressurization system to raise the pressure to the second pressure
and form a pressurized ozone-containing gas. The pressurized
ozone-containing gas is then withdrawn from the ozone
pressurization system. This method pressurizes the ozone-containing
stream without contaminating the stream with oil or water.
[0013] In one embodiment, the ozone pressurization system comprises
a pressurization vessel, the pressurization gas is fed into the
lower portion of the pressurization vessel, and the pressurized
ozone-containing gas is withdrawn from the upper portion of the
pressurization vessel.
[0014] In another embodiment, the pressurization system comprises a
first pressurization vessel and a last pressurization vessel. In
this embodiment, the pressurization vessels are fluidly connected
in series and the pressurizing gas is fed exclusively to the first
pressurization vessel.
[0015] The current inventive method also provides a method to
produce an ozonated liquid by feeding an ozone-containing gas from
the ozone source to an ozone pressurization system to establish a
first pressure, pressurizing the ozone pressurization system by
feeding a pressurization gas into the system; thus, raising the
pressure of the ozone-containing gas to a second pressure and
forming a pressurized ozone-containing gas. This method also places
a liquefied dry gas in an expansion vessel, and sparges the
pressurized ozone-containing gas through the liquefied dry gas to
form an ozonated liquefied dry gas, which is withdrawn from the
expansion vessel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] For a further understanding of the nature and objects of the
present invention, reference should be made to the following
detailed description, taken in conjunction with the accompanying
drawings, in which like elements are given the same or analogous
reference numbers and wherein:
[0017] FIG. 1 is a schematic of an embodiment of the current
invention for pressurizing ozone;
[0018] FIG. 2 is a schematic of another embodiment of the current
invention for pressurizing ozone;
[0019] FIG. 3 is a schematic of yet another embodiment of the
current invention for pressurizing ozone;
[0020] FIG. 4 is a schematic of still another embodiment of the
current invention for pressurizing ozone;
[0021] FIG. 5 is a schematic of an embodiment for pressurizing
ozone and producing an ozonated liquefied gas according to the
current invention; and
[0022] FIG. 6 is a graph showing the concentrations of ozone in a
liquefied gas attained by the current method of the current
invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0023] The current invention provides a method of pressurizing an
ozone-containing stream without destroying the ozone or
contaminating the ozone-containing stream with oil or water.
Furthermore, the method forms an ozonated liquefied dry gas by
bubbling the pressurized ozone-containing stream through a
reservoir of liquefied dry gas.
[0024] The current invention pressurizes ozone by feeding an
ozone-containing source to an ozone pressurization system to
establish a first pressure followed by pressurizing the ozone
pressurization system. The ozone pressurization system is
pressurized by feeding a pressurization gas to the ozone
pressurization system to raise the pressure to the second pressure
and form a pressurized ozone-containing gas. The pressurized
ozone-containing gas is then withdrawn from the ozone
pressurization system.
[0025] In one preferred method, the pressurization gas is a dry
gas. One preferred dry gas is CO.sub.2. The method pressurizes the
ozone-containing stream without contaminating the stream with oil
or water. The method preferable pressurizes the ozone-containing
stream to a pressure that is greater than about 150 psig.
Furthermore, the method can pressurize the ozone-containing stream
from a pressure of less than about 50 psig to a pressure that is
preferably greater than about 150 psig and even more preferably
greater than about 200 psig.
[0026] In one embodiment of the method, the ozone pressurization
system comprises a pressurization vessel, the pressurization gas is
fed into the lower portion of the pressurization vessel, and the
pressurized ozone-containing gas is withdrawn from the upper
portion of the pressurization vessel.
[0027] In another embodiment, the pressurization system comprises a
first pressurization vessel and a last pressurization vessel. In
this embodiment, the pressurization vessels are fluidly connected
in series and the pressurizing gas is fed exclusively to the first
pressurization vessel. In a preferred embodiment, the pressurized
gas mixture is withdrawn from the first pressurization vessel and
fed to the last pressurization vessel, while the pressurized
ozone-containing gas is withdrawn from the last pressurization
vessel. In a further preferred embodiment, the pressurization gas
is fed into a lower portion of the first pressurization vessel
while the pressurized gas mixture is withdrawn from an upper
portion of that first pressurization vessel. The pressurized gas
mixture is then fed into a lower portion of the last pressurization
vessel and the pressurized ozone-containing gas is finally
withdrawn from an upper portion of the last pressurization
vessel.
[0028] In yet a further embodiment, the pressurization system
comprises a number of pressurization vessels in series and includes
the steps of withdrawing a pressurized gas mixture from the first
pressurization vessel, feeding the pressurized gas mixture to a
successive pressurization vessel, and transferring the pressurized
gas mixture from the successive pressurization vessel to the last
pressurization vessel. This embodiment, like those above withdraws
the pressurized ozone-containing gas from the last pressurization
vessel. One further embodiment of this method feeds the
pressurization gas into a lower portion of the first pressurization
vessel, withdraws the pressurized gas is from an upper portion of
the first pressurization vessel, feeds the pressurized gas mixture
into a lower portion of the successive pressurization vessel,
withdraws that pressurized gas from an upper portion of the
successive pressurization vessel, and ultimately transfers the
pressurized gas mixture into a lower portion of the last
pressurization vessel.
[0029] The current inventive method also provides an ozonated
liquid by feeding an ozone-containing gas from the ozone source to
an ozone pressurization system to establish a first pressure,
pressurizing the ozone pressurization system by feeding a
pressurization gas into the system thus raising the pressure of the
ozone-containing gas to a second pressure and forming a pressurized
ozone-containing gas. The method also places a liquefied dry gas in
an expansion vessel, and sparges the pressurized ozone-containing
gas through the liquefied dry gas to form an ozonated liquefied dry
gas, which is withdrawn from the expansion vessel. This method may
further include steps of withdrawing a vent gas from the expansion
tank and recycling the vent gas to a liquefied dry gas storage
vessel. In some embodiments, the sparging occurs substantially
continuously.
[0030] Referring to FIG. 1, one embodiment of the current method
provides an ozone-containing gas 102 from an ozone source 104.
Ozone can be generated in commercially available ozone generator
known to one of ordinary skill in the art. The ozone generation
unit preferably uses a pure oxygen feed, to form the
ozone-containing gas 102, which preferably contains about 6 to
about 13 wt % ozone in oxygen, and more preferably about 9 to about
11 wt % ozone. The ozone pressurization system 106 is purged with
the ozone-containing gas 102 to establish a concentration of ozone
in the entire ozone pressurization system 106. Then, the ozone
pressurization system 106 is pressurized with the ozone-containing
gas 102 to set an initial pressure, for instance about 5 to about
25 psig, in the entire ozone pressurization system 106. The higher
the initial pressure in the compression system, the higher final
pressure that can be achieved. The entire ozone pressurization
system 106 is then isolated from the ozone generator. The
ozone-containing gas 102 is pressurized in an ozone pressurization
system 106 to form a pressurized ozone-containing gas 108. To form
the pressurized ozone-containing gas 108, the ozone-containing gas
102 is fed to the ozone pressurization system 106 to establish a
concentration of ozone-containing gas throughout the ozone
pressurization system 106 at first pressure in the ozone
pressurization system 106. The first pressure is preferably less
than about 100 psig, more preferably less than about 50 psig and
even more preferably less than about 30 psig. Next, a
pressurization gas 110 is fed to the ozone pressurization system
106 to raise the pressure in the ozone pressurization system 106 to
a second pressure. As the pressurization gas 110 enters the ozone
pressurization system 106, the ozone-containing gas in the ozone
pressurization system 106 is compressed. It is believed that if the
density of the pressurization gas 110 and the ozone-containing gas
102 is substantially different, the gases stratify in the tanks and
mixing is minimal. The final result is a compressed
ozone-containing feed mixture typically containing close to, but
somewhat lower concentration of ozone in oxygen that the
ozone-containing gas 102 in the upper portion of any vessels in the
ozone pressurization system 106. The pressurization gas 110 feed to
the ozone pressurization system 106 is stopped when the desired
second pressure is reached. The pressurized ozone-containing gas
108 is then withdrawn from the ozone pressurization system 106. The
ozone pressurization system 106 preferably comprises at least one
pressurization vessel 112. Furthermore, the pressurization gas 110
is preferably fed to a lower portion of the pressurization vessel
112 and more preferably fed to the bottom portion of the
pressurization vessel 112. The pressurized ozone-containing gas 108
is preferably removed from an upper portion of the pressurization
vessel 112 and more preferably removed from the top of the
pressurization vessel 112. In one preferred embodiment, the
pressurization gas 110 is fed at a slow flow rate to the
pressurization system 106 in order to minimize the mixing for the
ozone-containing gas 102 and the pressurization gas 110. It is
preferable to maintain laminar flow rates in the pressurization
vessel 112.
[0031] Still referring to FIG. 1, the pressurization gas 110 is fed
to the pressurization vessel to raise the pressure in the ozone
pressurization system 106 to a second pressure of greater than
about 100 psig, more preferably greater than about 150 psig, and
even more preferably greater than about 200 psig. Then, the
pressurized ozone-containing gas 108 can be withdrawn from the
ozone pressurization system 106. Using this method, it is feasible
to pressurize an ozone-containing stream to pressures of greater
than about 500 psig and even greater than about 1,000 psig without
destroying the ozone. Furthermore, a substantial portion of the
ozone (O.sub.3) remains relatively undiluted. Still further, the
resulting pressurized ozone-containing gas 108 is substantially
free of oil, water, or other undesirable contaminants. In one
preferred embodiment, the pressurized ozone-containing gas 108
contains less than about 0.05 wt % water, preferably contains less
than about 200 ppm wt water, and more preferably less than about 20
ppm wt water.
[0032] One preferred pressurization gas 110 is a dry gas. The dry
gas can be any suitable non-aqueous gas, but is preferably a
liquefied gas, particularly a liquefied gas with a high gas density
compared to the ozone-containing gas 102. The dry gas preferably
contains less than 0.05 wt % water, and more preferably containing
less than 20 ppm wt water. In one preferred embodiment, the
pressurization gas 110 is preferably a dry gas that is stored as a
liquid, such as CO.sub.2. The liquefied dry gas is removed from the
liquid storage vessel and expanded to form the pressurization gas
110. One preferred embodiment uses a pressurization gas 110 that
has a gas density that is higher that the gas density of the
ozone-containing gas 102. This pressurization gas 110 is preferably
cold after expansion to provide a pressurization gas at the highest
gas density possible for that gas. In one embodiment, the
pressurization gas is preferably less than about 20.degree. C.
after expansion, and more preferably less than about 10.degree. C.
after expansion. By using a pressurization gas 110 that is higher
in gas density than the ozone-containing gas 102, and by feeding
the pressurization gas 110 slowly, dilution of the ozone-containing
gas 102 with the pressurization gas 110 is minimized. Without being
limited by this theory, it is believed that the higher gas density
pressurization gas 110 layers out in the pressurization vessel 112
below the lower density ozone-containing gas 102 already in the
vessel. In one embodiment, the concentration of ozone in the
pressurized ozone-containing gas 108 is at least about 70% of the
concentration of ozone in the ozone-containing gas 102, more
preferably at least 80% of the concentration of ozone in the
ozone-containing gas 102, and even more preferably at least about
90% of the concentration of ozone in the ozone-containing gas
102.
[0033] In one embodiment, a continuous flow of pressurized ozone
gas 110 is supplied by using a plurality of ozone pressurization
systems 106 operated in a "round robin" to maximize the use of the
ozone generator and minimize the waste of pressurization gas 110 by
cross-tying (not shown) the sets of ozone pressurization systems
106.
[0034] Referring to FIG. 2, one embodiment of the current method
utilizes an ozone pressurization system 106 that comprises a
plurality of pressurization vessels, which comprise at least a
first pressurization vessel 202 and a last pressurization vessel
204. An upper portion of the first pressurization vessel 202 and a
lower portion of the last pressurization vessel 204 are connected
by a fluid connection means 206. The fluid connection means can be
any type or combination of pipe, conduit, vessel, valve, orifice,
chamber, or other flow passage that allows a pressurized gas
mixture to flow from one vessel to another. One preferred fluid
connection means 206 has at least part of the means that is smaller
in diameter than the first pressurization vessel 202 or the last
pressurization vessel 204. In this preferred method, a pressurized
gas mixture is withdrawn (or pushed) from the upper portion of the
first pressurization vessel 202 and fed into a lower portion of the
last pressurization vessel 204 as the pressurization gas 110 is fed
into the lower portion of the first pressurization vessel 202.
Eventually, the first pressurization vessel 202 will be completely
filled with a gas mixture that primarily comprises the
pressurization gas 110. Having a plurality of pressurization
vessels helps prevent the pressurization gas 110 from mixing with
the ozone-containing gas 102. The compressed ozone-containing gas
110 is withdrawn from the last pressurization vessel 204. The last
pressurization vessel 204 is preferably isolated from any upstream
pressurization vessels to prevent unwanted dilution of the
pressurized ozone mixture. The pressure from the last
pressurization vessel 204 is allowed to drop as the
ozone-containing gas 110 is fed to the process.
[0035] Referring to FIG. 3, one embodiment of the current method
uses a plurality of pressurization vessels comprising more than two
pressurization vessels fluidly connected in series. The
ozone-containing gas 102 is first fed to fill the plurality of
pressurization vessels with the ozone-containing gas 102 at a first
pressure. Next, the pressurization gas 110 is fed into a first
pressurization vessel 202 in the series of pressurization vessels
and the pressurized ozone-containing gas 108 flows out of a last
pressurization vessel 204 in the series of pressurization vessels.
The embodiment of FIG. 3 uses an ozone pressurization system that
comprises a first pressurization vessel 202, a successive
pressurization vessel 303, and a last pressurization vessel 204. In
this embodiment, a pressurized gas mixture is withdrawn from the
first pressurization vessel 202 and fed to the successive
pressurization vessel. The pressurized gas mixture then flows from
the successive pressurization vessel to the last pressurization
vessel 204. The pressurized ozone-containing gas 108 is then
withdrawn from the last pressurization vessel 204 after the ozone
pressurization system 106 reaches a second pressure.
[0036] Still referring to FIG. 3, in one embodiment, the
pressurization gas is fed into a lower portion of the first
pressurization vessel 202. A pressurized gas mixture is withdrawn
from an upper portion of the first pressurization vessel 202 and
fed into a lower portion of the successive pressurization vessel
302 via a first conduit 304. The pressurized gas is then withdrawn
from an upper portion of the successive pressurization vessel 302
and transferred into a lower portion of the last pressurization
vessel 204 via a second conduit 306. Finally, the pressurized
ozone-containing gas 108 is withdrawn from the upper portion of the
last pressurization vessel 204 after the ozone pressurization
system 106 reaches a second pressure.
[0037] Referring to FIG. 4, one embodiment of the current method
uses a plurality of pressurization vessels fluidly connected in
series. In this embodiment, the ozone pressurization system 106
comprises a first pressurization vessel 202, at least two
successive pressurization vessels 402, 404, and a last
pressurization vessel 204, all fluidly connected in series. The
ozone-containing gas 102 is first fed to fill all of the
pressurization vessels 202, 204, 402, 404 with the ozone-containing
gas 102 at a first pressure. The pressurization gas 110 is fed into
a first pressurization vessel 202 and the pressurized
ozone-containing gas 108 flows out of a last pressurization vessel
204. In this embodiment, a pressurized gas mixture is withdrawn
from the first pressurization vessel 202 and fed to the successive
pressurization vessels 402 and 404 in series via a plurality of gas
transfer conduits 406, 408, 410. The pressurized gas mixture then
flows from the successive pressurization vessels 402 and 404 to the
last pressurization vessel 204. The pressurized ozone-containing
gas 108 is then withdrawn from the last pressurization vessel 204
after the ozone pressurization system 106 reaches a second
pressure. As described above, in a preferred embodiment, the
incoming gases flow into the lower portions of the respective
vessels and the outgoing gases exit the upper portions of the
respective vessels.
[0038] In one embodiment of the current invention, a continuous
supply of pressurized ozone feed is supplied. In the embodiment,
the pressurization vessels upstream of the last pressurization
vessel 204 are replenished with ozone-containing gas 102. To
accomplish this, the tanks upstream of the last pressurization
vessel 204 are vented of their pressure, purged, re-filled with the
ozone-containing gas 102, and re-pressurized as described above.
This new batch of pressurized gas may then be released into the
last pressurization vessel 204. This re-filling gives a slightly
more dilute ozone mixture. A more efficient arrangement consists of
several sets of tanks, operated in a "round robin" to maximize the
use of the ozone generator, capture all pressurized ozone that does
not reach the last pressurization vessel 204, and minimize the
waste of pressurization gas 110 by allowing the sets of tanks to be
cross-tied.
[0039] Now referring to FIG. 5, the current inventive method also
provides an ozonated liquefied dry gas 502 by transferring a
liquefied dry gas 504 to an expansion vessel 506 and sparging the
pressurized ozone-containing gas 110 through the liquefied dry gas
to form the ozonated liquefied dry gas 502. In one embodiment of
this method, the liquefied dry gas 504 is stored in a liquefied dry
gas storage vessel 508 at a pressure suitable to maintain the dry
gas in liquid form. The liquefied dry gas 504 is transferred to the
expansion vessel 506 where the pressure is somewhat less than the
pressure in the liquefied dry gas storage vessel 508. The ozone
pressurization system 106 pressurizes an ozone-containing gas 102
as described in the previous embodiments to form a pressurized
ozone-containing gas 110 at a second pressure, which is above the
pressure in the expansion vessel 506. The second pressure is
preferably at least about 50 psig above the pressure in the
expansion vessel 506, and more preferably at least about 100 psig
above the pressure in the expansion vessel 506. The pressurized
ozone-containing gas 110 is then sparged through the liquefied dry
gas in the expansion vessel 506 to form the ozonated liquefied dry
gas 502. The ozonated liquefied dry gas is withdrawn from the
expansion vessel 506 after sufficient sparging to assure the liquid
contains a desired amount of ozone. In one embodiment, the
expansion vessel 506 is substantially filled with the liquefied dry
gas 504 and then the pressurized ozone-containing gas 110 is
sparged through the liquid on a batch basis. In other embodiments,
there is a continuous flow of liquefied dry gas 504 into the
expansion vessel 506 and the pressurized ozone-containing gas 110
is sparged continuously through the liquid. This method may further
include steps of withdrawing a vent gas 510 from the expansion
tank. In some embodiments, the vent gas 510 is fed to a recovery
system 512 for recovery and recycling of the vent gas back to the
liquefied dry gas storage vessel
[0040] Still referring to FIG. 5, one embodiment of the current
invention uses CO.sub.2 as the liquefied dry gas. In this
embodiment, the pressure in the liquefied dry gas storage vessel
508 is about 200 to about 400 psig. The liquefied dry gas 504 is
transferred to the expansion vessel 506 where the pressure is
preferably about 100 to about 200 psig, more preferably about 150
to 200 psig, and even more preferably about 200 to about 300 psig.
The ozone pressurization system 106 provides the pressurized
ozone-containing gas 110 at a second pressure, which is above the
pressure in the expansion vessel 506, preferably at least about 50
psig above the pressure in the expansion vessel 506, and more
preferably at least about 100 psig above the pressure in the
expansion vessel 506. The ozonated liquefied dry gas is withdrawn
from the expansion vessel 506 after sufficient sparging to assure
the liquid CO.sub.2 contains a desired amount of ozone. By this
method, an ozonated liquid CO.sub.2 can be supplied containing at
least about 200 ppm wt ozone, and more preferably greater than
about 250 ppm wt ozone. As is shown in FIG. 5, the current method
provides an ozonated liquid with a much higher concentration of
ozone that the prior art methods of saturating water with
ozone.
[0041] Another embodiment of the dry gas pressurization method
described above is used to dose other liquids, including aqueous
and dry (non-aqueous) liquids. In one embodiment of the invention,
the dry gas compression method is used to ozonate a liquid, where
the liquid is at pressures greater than about 150 psig. In this
embodiment, a liquid is placed into a pressure vessel where the
pressure is greater than about 150 (or is raised to above this
pressure), preferably great than about 200 psig, and more
preferably greater than about 300 psig. The ozone pressurization
system provides the pressurized ozone-containing gas at a second
pressure, which is above the pressure in the pressure vessel,
preferably at least about 50 psig above the pressure in the
expansion vessel, and more preferably at least about 100 psig above
the pressure in the expansion vessel. The ozonated liquid is
withdrawn from the pressure vessel after sufficient sparging to
assure the liquid contains a desired amount of ozone.
[0042] Although the present invention has been described in
considerable detail with reference to certain preferred versions
and examples thereof, other versions are possible. For instance,
any liquid which one skilled in the art wishes to saturate with
ozone can be substituted for the liquefied dry gas of the current
invention in the method. Furthermore, there is a large variety of
configurations of vessels, pipes, and other equipment that can be
used as pressurization vessels. Clearly, the current invention may
be used in a variety of processes for processing food, or non-food
items. Therefore, the spirit and scope of the appended claims
should not be limited to the description of the preferred versions
contained herein.
[0043] All the features disclosed in this specification (including
any accompanying claims, abstract, and drawings) may be replaced by
alternative features serving the same, equivalent or similar
purpose, unless expressly stated otherwise. Thus, unless expressly
stated otherwise, each feature disclosed is one example only of a
generic series of equivalent or similar features.
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