Ozone generator and method of producing ozone

Details Ozone generator and method of producing ozone Ozone generator and method of producing ozone

1997-05-28

2001-02-27

Mayekar, Kishor (Department: 1741)

Chemistry: electrical and wave energy

Processes and products

Electrostatic field or electrical discharge

C422S186110, C422S186200, C422S186190

Reexamination Certificate

active

06193852

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an ozone generator. The present invention further relates to a low temperature ozone generator with improved ozone output. The present invention still further relates to a method of producing ozone using a cryogenic cooling medium.
BACKGROUND OF THE INVENTION
Ozone finds a wide variety of uses due to its very strong oxidant properties. Common uses for ozone include oxide film formation, e.g., semiconductor film formation, sterilization, and waste water treatment. A wide variety of methods have been proposed to generate ozone efficiently. The quantity of ozone produced by a given process or generator depends on a number of factors such as reactant gas concentration, electric power applied, temperature and gas flow rate.
Though a strong oxidant, ozone is not particularly stable and tends to decompose at elevated temperatures to reform diatomic oxygen. To achieve higher ozone concentrations, some propose to increase power density to the generator. While resulting in higher ozone concentrations, this approach requires significantly more power input and also results in higher system temperatures. As the temperature of the exit gas stream increases, so too does the decomposition of the ozone formed by the process.
Some form of cooling is typically used in the industry to withdraw unwanted heat produced during ozone generation. Cooling can be accomplished by varying the flow rate or flow path of the reactant gas through the generator. One example of this cooling method can be found in U.S. Pat. No. 4,213,838. Other gas driven cooling configurations include countercurrent flow of the reactant gas behind the dielectric members, as proposed in U.S. Pat. No. 5,008,087. However, the most common method for removing unwanted heat is the use of a fluid coolant, most often room temperature water. One example of water cooling is the jacket cooling arrangement described in U.S. Pat. No. 4,954,321.
U.S. Pat. No. 5,366,703 suggests that the efficient production of ozone can be accomplished using gas compression. This arrangement introduces a reactant gas into a generator at a pressure of between 1 and 3 bar and at a temperature of not greater than 50° C. The gas is subjected to ozone generation and is then isothermally compressed to result in an ozone containing stream having a temperature not greater than the temperature of the feed gas and a pressure of at least 3 bar. This process however, suffers from the disadvantage that it requires both compression and cooling to obtain reasonable ozone concentrations.
The present invention overcomes the disadvantages of the prior art and produces higher ozone concentrations without the additional process of gas compression. Furthermore, the present invention improves the concentration of generated ozone by manipulating the temperature and concentration of the reactant gas.
SUMMARY OF THE INVENTION
The present invention provides an ozone generator cooled by a cryogenic cooling medium, such as liquid nitrogen, to improve the concentration of ozone produced with a given reactant stream.
The present invention also provides a method of increasing ozone production by not only using a cooling medium at temperatures below about 0° C. to cool the ozone generator, but, in some cases, also mixing coolant with the reactant gas to reduce the temperature of the reactant gas stream without affecting the available oxygen for ozone production.
To achieve these and other advantages and in accordance with the purposes of the invention, as embodied and broadly described herein, there is disclosed:
An ozone generator including ozone generation means having associated therewith means for introducing a reactant gas; means for contacting the ozone generation means with a cooling medium at not greater than about 0 C. means for withdrawing a portion of the cooling medium after it has contacted said generation means; means for converting the extracted cooling medium to a gaseous coolant and means for introducing the gaseous coolant to the reactant gas stream.
There is further disclosed:
A method for producing ozone including providing a stream of reactant gas containing oxygen; contacting the reactant gas with an ozone generation means to convert a portion of the reactant gas to ozone; contacting the ozone generation means with a cooling medium at not greater than about 0 C. to cool the ozone; removing the cooling medium after it contacts the ozone generation means; converting the cooling medium to a gaseous coolant and introducing at least a portion of the gaseous coolant into the stream of reactant gas.
There is still further disclosed:
A method for producing ozone including providing a stream of reactant gas containing oxygen; contacting the reactant gas with an ozone generation means to convert a portion of the reactant gas to ozone; contacting the ozone generation means with a cooling medium at not greater than about 0° C. to cool the ozone; removing the cooling medium after it contacts the ozone generation means; and cooling the ozone gas stream after it exits the ozone generator with at least a portion of the cooling medium.
There is also disclosed:
A method for producing ozone including flowing reactant gas containing oxygen into an ozone generator to convert a portion of the reactant gas to ozone; contacting the ozone generator with a cooling medium at not greater than about 0° C. to cool the ozone; and withdrawing a product stream containing the ozone generated in the ozone generator.
Further advantages of the invention will be set forth in part in the description which follows and in part will be apparent from the description, or may be learned by practice of the invention. The advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
The accompanying drawings, are included to provide a further understanding of the invention and are incorporated in and constitute a part of the specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.


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