Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Waste gas purifier
Reexamination Certificate
2002-01-08
2004-06-01
Tran, Hien (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Waste gas purifier
C422S170000, C422S172000, C422S177000
Reexamination Certificate
active
06743402
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a purifier of a noxious gas containing all kinds of hazardous components or malodorous components.
BACKGROUND ART
There are noxious gases containing hazardous components or malodorous components such as ethylene oxide gas used for sterilization procedure in hospitals or the like, carbon monoxide or hydrocarbon etc. exhausted from e.g. combustion equipment or from drying equipment for organic solvents. These hazardous components and these malodorous components should be purged from noxious gases before the noxious gases are released to the atmosphere. One approach to purify a noxious gas is to pass the noxious gas through an oxidation catalyst. The use of an oxidation catalyst can accelerate the oxidation reaction of ethylene oxide gas, carbon monoxide, hydrocarbon or the like at a lower temperature (for example, 200 to 400° C.) than that for burning directly, so that the noxious gas can be changed into innocuous carbon dioxide or water vapor.
Such a gas purifier has, depending on e.g. the amount of catalyst stored inside, limitations with respect to the quantity of noxious gas components to be purified per unit of time (hereinafter referred to as “processing capability”). If a noxious gas in excess of the upper limit of this processing capability (concentration or gas volume) is supplied to the purifier, the noxious gas is exhausted without being sufficiently purified. In using this type of gas purifier, it is therefore important to prevent the supply quantity of noxious gas components, even temporarily, from exceeding the processing capability of the purifier.
However, a noxious gas is not always produced in a constant quantity and in a constant concentration. It is rather common that the quantity and the concentration of gas produced fluctuate to a large extent. Moreover, depending on the release source, a noxious gas is often produced intermittently. In such a case where the quantity and the concentration of noxious gas fluctuate, the installation of a purifier with processing capability covering the peak quantity of noxious gas is not an economical solution from the viewpoint of cost of the device and space to be occupied by the device.
Thus, consideration has been given to equipping a purifier with a cushioning device (buffer), which supplies the noxious gas to the purifier after the changes of quantity and concentration of a noxious gas have been smoothed, namely reduced, as much as possible. The simplest example of such a buffer is the use of a variable-volume container such as a plastic bag. In this case, the produced noxious gas is gathered temporarily in a plastic bag and then fed in an almost constant quantity into a purifier by the operation of a suction fan or the like of the purifier.
However, even if the use of a variable-volume container as a buffer can reduce fluctuations in the quantity of the supplied noxious gas, fluctuations of noxious gas concentration cannot be controlled. In other words, it is not possible to prevent the concentration of noxious components (components to be purified) contained in a noxious gas from fluctuating. Furthermore, although a plastic bag is inexpensive, this plastic bag needs to have a considerably large size for demonstrating sufficient buffer effects. As a result, a large space is required for installation, and the installation method is also not easy. Additionally, for safety reason, the plastic bag may have to be placed inside a casing having a certain degree of mechanical strength, which forms a dual structure resulting in higher cost. There are also inflammable gases and explosive gases included in noxious gases, so that this aspect should be taken into account as well.
Accordingly, it is an object of the present invention to provide a purifier of a noxious gas equipped with a buffer means for purifying the noxious gas economically and safely when the quantity or the concentration of the noxious gas fluctuates.
DISCLOSURE OF INVENTION
In order to accomplish the above object, a purifier of a noxious gas of the present invention is provided with means for supplying a gas containing a noxious gas component, buffer means using a liquid which dissolves the noxious gas component in the supplied gas temporarily and later releases the dissolved noxious gas component, and means for purifying the noxious gas component in the gas supplied from the buffer means.
According to the purifier using such a liquid, the noxious gas component can be supplied to the purification means after having been reduced at least to a certain value. Furthermore, there is no need to install a special apparatus or facility for carrying out this process. The size of the device itself can be determined appropriately according to the required processing capability and will not be unnecessarily large. Furthermore, if a noncombustible and inactive liquid is chosen as the liquid to be used for the buffer means, even inflammable and explosive noxious gases can be treated safely.
Apart from the present patent application, the applicant of the present invention has filed another patent application of a purifier equipped with buffer means using a gas adsorbent such as activated carbon (Japanese Patent Application (Tokugan Hei) 9-250245). According to this device, the noxious gas can be supplied to the purification means after the concentration is controlled at least to a certain value. And the same with the purifier of the present invention, the device in the aforementioned other application also demonstrates excellent cost performance. However, a certain kind of noxious gas such as ethylene oxide generates heat (ca. 70 to 80° C.) when adsorbed to activated carbon etc., so that the noxious gas may not be purified successfully. On the other hand, the purifier of the present invention has the advantage of solving this problem of heat generation by using a liquid for the buffer means.
In the present invention, a noxious gas implies not only a gas which is hazardous for organisms including human beings or harmful to the environment, but also to all kinds of gases that preferably are removed, such as a hazardous gas of inflammable or explosive nature, an unpleasant gas with offensive odor, and a gas containing this kind of hazardous and unpleasant gas. The gas may be inorganic or organic. As examples of noxious gases, there are a volatile organic compound gas such as above-mentioned ethylene oxide, toluene, and acetone etc., and an inorganic compound gas etc. such as ammonia or the like. Gases containing a noxious gas can be listed, for example, emission gas of a sterilization apparatus used for sterilizing medical instruments (ethylene oxide-containing gas), emission gas of an incinerator, emission gas of a plant, exhaust gas of an organic solvent dryer, exhaust gas of an incinerator, exhaust gas of a draft chamber, and exhaust gas of a paint booth.
In the purifier of the present invention, it is preferable that the liquid in the buffer means dissolves the noxious gas component when the concentration of the noxious gas component in the supplied gas is high and releases the noxious gas component dissolved thus far when the concentration is low. Accordingly, the noxious gas component can be supplied to the purification means in a constant concentration, and the purification can be carried out efficiently. Such a function originally should be given to the liquid itself. However, if this function is not carried out sufficiently, as will be described later, a gas containing a noxious gas or a clean gas may be blown into the liquid to force dissolution or release.
It is preferable that the purifier of the present invention includes means for supplying a clean gas, with which the clean gas is supplied into the liquid in the buffer means. By supplying the clean gas into the liquid in the buffer means, the noxious gas dissolved in the liquid can be released even more. As a result, this liquid is purified and can be used once again for dissolving a noxious gas with high concentration.
There are two ways of supplying a clean gas in
Merchant & Gould P,C,
Tran Hien
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