Vaporizer using electrical induction to produce heat

Details Vaporizer using electrical induction to produce heat Vaporizer using electrical induction to produce heat

2002-06-12

2004-05-11

Leung, Philip H. (Department: 3742)

Electric heating

Inductive heating

With heat exchange

C219S629000, C219S635000, C422S022000

Reexamination Certificate

active

06734405

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to a vapor generator. It finds particular application in conjunction with steam and hydrogen peroxide vapor systems used in connection with medical device disinfection and sterilization and in the sanitation, disinfection, and sterilization of rooms, buildings, large enclosures, and bottling, packaging, and other production lines and will be described with particular reference thereto. It should be appreciated, however, that the invention is also applicable to other chemical vaporization systems such as those employing other peroxides, peracids, and the like.
BACKGROUND OF THE INVENTION
A variety of microbial decontamination processes employ sterilizing vapors, such as steam or a mixture of water with another antimicrobial (e.g., hydrogen peroxide vapor), in relatively large quantities. Steam sterilizers, for example, employ pressurized high temperature dry steam as a sterilizing vapor. Unvaporized water droplets can shield microbes or prions from the steam. Hydrogen peroxide vapor systems use a flow of vapor, typically at around atmospheric pressure or below. Again, water droplets can shield microbes and prions from the peroxide.
Medical, pharmaceutical, dental, and food packaging items are often sterilized prior to use or reuse, in such systems. Vapors are also used in the decontamination of sterile enclosures and other clean rooms used by hospitals and laboratories for conducting tests in a microorganism-free environment, areas that have been microbially contaminated, and the like. Processing equipment for pharmaceuticals and food, freeze driers, and meat processing equipment are also advantageously disinfected or sterilized with a vapor.
In the case of steam, for example, microbial decontamination systems often create the steam by boiling water inside a reservoir of a steam generator, such as a boiler. A large heating element is usually located over the bottom surface of the reservoir to maintain a supply of boiling water.
In the case of other water-based antimicrobial vapors, such as hydrogen peroxide vapor, a vaporizer outside the chamber generates a flow of vapor. Typically, a solution of about 35% hydrogen peroxide in water is injected into the vaporizer as fine droplets or a mist through injection nozzles. The droplets contact a heated surface which heats the droplets to form the vapor, without breaking it down to water and oxygen. A carrier gas is circulated over the heat transfer surface to absorb the peroxide vapor.
Such vapor generation methods have disadvantages when large quantities of vapor are desired or vapor is needed at short notice. Boilers tend to be relatively large pieces of equipment, which work best when the wattage is spread out over a large heating element surface area. This keeps the watt density low and extends the life of the heating element. The large heating element surface area, however, takes up considerable space. Additionally, to avoid damage to the heating element, it is completely immersed in water. Thus, it takes some time to heat the large volume of water to steam temperature in order for steam generation to begin. It is expensive to maintain a supply of over 100° C. water ready for a demand. Any unused heated water generally has to be cooled in a heat exchanger before it is disposed of in a municipal waste water system.
Vaporized hydrogen peroxide is a particularly useful vapor sterilant for both vacuum sterilizing systems and rooms and other large enclosures. It is effective at or close to room temperature, which reduces the potential for thermal degradation of associated equipment and items to be sterilized or disinfected within the sterilizer enclosure. In addition, hydrogen peroxide readily decomposes to water and oxygen, thus simplifying disposal.
As the size of the sterilizer or enclosure increases, or the demand for hydrogen peroxide is increased, the efficiency of the vaporization system becomes more significant. The capacity of the vaporizer is limited in a number of ways. First, the vaporization process creates a pressure increase, reducing the flow of air through the vaporizer. Second, to maintain sterilization efficiency, the pressure at which the vapor is generated is limited to that at which the hydrogen peroxide is stable in the vapor state. Third, the time taken to generate the hydrogen peroxide is dependent on the time taken to heat the heated surface to vaporization temperature.
One solution has been to increase the size of the vaporizer, the injection rate of hydrogen peroxide into the vaporizer, and the flow rate of carrier gas. However, the carrier gas tends to cool the heating surface, disrupting the vaporization process. Heating the heating surface to a higher temperature breaks down the hydrogen peroxide.
Yet another solution is to use multiple vaporizers to feed a single enclosure. The vaporizers may each be controlled independently, to allow for variations in chamber characteristics. However, the use of multiple vaporizers adds to the cost of the system and requires careful monitoring to ensure that each vaporizer is performing with balanced efficiency. None of these solutions addresses the initial warm up time needed for raising the temperature of the vaporizer to vaporization temperature.
The present invention provides a new and improved vaporization system and method which overcomes the above-referenced problems and others.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, a vapor decontamination system is provided. The system includes a vaporizer for vaporizing a liquid which includes an antimicrobial compound into vapor. The vaporizer includes means for generating a changing magnetic field and an induction vessel which intercepts the changing magnetic field, causing it to heat up. The induction vessel supplies heat to the liquid to convert the liquid to the vapor. A duct is connected with an outlet of the vaporizer for supplying the vapor to a defined region.
In accordance with another aspect of the present invention, a method of microbially decontaminating a defined area or an item within the defined area is provided. The method includes inductively heating a vessel and passing a liquid into the vessel. The inductively heated vessel vaporizes the liquid to form an antimicrobial vapor. The vapor is flowed out of the vessel to the defined area to microbially decontaminate at least one of the defined area and the item.
In accordance with another aspect of the present invention, a vaporization system is provided. The system includes an induction coil which generates an oscillating magnetic field. An induction vessel is positioned to intercept the magnetic field and which is heated by the magnetic field. An interior passage having an inlet and an outlet is defined within the induction vessel and is heated thereby. A source of liquid is fluidly connected with the inlet to the passage, the liquid being converted to vapor as it passes through the passage.
One advantage of the present invention is that a high output of sterilant vapor is achieved.
Another advantage of the present invention is that it enables sterilant vapor to be generated “on demand” at short notice.
Another advantage resides in reduced resistive electrical power loads.
Another advantage of the present invention is that it enables vapor concentration levels to be raised rapidly, particularly when used with smaller enclosures, thereby reducing the conditioning time.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.


REFERENCES:
patent: 4013742 (1977-03-01), Lang
patent: 4236056 (1980-11-01), Allen et al.
patent: 4310738 (1982-01-01), Moretti et al.
patent: 4678881 (1987-07-01), Griffith
patent: 5222185 (1993-06-01), McCord, Jr.
patent: 5286942 (1994-02-01), McFadden et al.
patent: 5324904 (1994-06-01), Cresswell et al.
patent: 5750072 (1998-05-01), Sangster et al.
patent: 5773798 (1998-06-01), Fukumu

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