Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – With means applying electromagnetic wave energy or...
Patent
1995-01-19
1996-04-02
Mai, Ngoclan
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
With means applying electromagnetic wave energy or...
42218621, 42218622, 42218629, 422906, 422907, B01J 1912
Patent
active
055038077
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the generation of chemically active species, and more specifically, to the generation of such species for use in sterilisation processes.
The use of plasma-generated active gaseous species for sterilisation purposes is well-known. For example, such processes are described in our co-pending published patent application GB 2,253,144A (PCT application No. WO92/15336), U.S. Pat. Nos. 3,383,163; 3,851,436; 3,948,601; 4,207,286; 4,321,232; 4,348,357; 4,643,876; Japanese Application Disclosure numbers 103460/83; 162276/83; European patent application number 387022A, and others.
However, conventionally, the plasma is at a gas pressure well below atmospheric, typically in the range 1-10 torr. Such relatively low gas pressures place a limit on the amount of active species which can be generated and hence determine also the length of time required for the sterilisation of an object. Another disadvantage of the prior art systems is that their use involves relatively large scale vacuum systems with all the expense and operating procedures attached thereto.
It is an object of the present invention to provide an apparatus and method for producing active gaseous species at pressures substantially higher than hitherto.
According to the present invention there is provided an apparatus for generating chemically active gaseous species and exposing a substance to the chemically active gaseous species, comprising an activation chamber, means for generating an electric field within the activation chamber, a pair of electric field enhancing electrodes positioned within the activation chamber whereby a localised electric field sufficient to generate the chemically active species can be established, means for directing a gaseous medium adapted to provide the chemically active species through the region of maximum electric field in the proximity of the electric field enhancing electrodes, means for extracting the chemically active gaseous species from the activation chamber and a reaction vessel adapted to receive a substance to be exposed to the chemically active gaseous species.
In a preferred embodiment of the invention, the field enhancing electrodes consist of a pair of co-axial, opposed projections, at least one of which has an axial hole through which the chemically activated species can be withdrawn from the activation chamber, thereby to cause the gaseous medium to be directed into the region of maximum electric field between the field enhancing electrodes.
Also according to the invention there is provided a method of generating chemically active gaseous species, including the operations of establishing a high frequency alternating electric field in an activating chamber, shaping the electric field to provide a localised region of enhanced electric field such as to be capable of generating an electric discharge in a gaseous medium at a pressure of at least fifty millibars, admitting to the activation chamber at a pressure of at least fifty millibars a gaseous medium, the gaseous medium being adapted to provide the chemically active species under the influence of an electric discharge excited by the localised enhanced electric field, directing the gaseous medium through the localised region of enhanced electric field and extracting the chemically active species from the activation chamber, and admitting the chemically active species to a reaction chamber.
The chemically active species may be in the form of stable molecular species such as ozone or hydrogen peroxide, ions, free radicals, or electronically or vibrationally excited atomic or molecular species.
If the chemically active species are to be used for the sterilisation of objects such as surgical instruments or other objects which include degradable materials in their construction, then free radicals or stable chemically active molecular species are preferred. If the chemically active species are to be used to promote reactions such as polymerisation, then free radicals or vibrationally excited molecules are the preferred chemically ac
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Bayliss Keith H.
Griffiths Christopher N.
Raybone David
Stedman John
Hinds William R.
Jenkins Daniel
Mai Ngoclan
United Kingdom Atomic Energy Authority
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