Electron beam-irradiating reaction apparatus

Details Electron beam-irradiating reaction apparatus Electron beam-irradiating reaction apparatus

2001-07-10

2004-04-20

Stephens, Juanita (Department: 2853)

Radiant energy

Irradiation of objects or material

Ion or electron beam irradiation

C313S420000

Reexamination Certificate

active

06724003

ABSTRACT:

TECHNICAL FIELD
The present invention relates to an electron beam-irradiating reaction apparatus for irradiating a desired object with an electron beam and changing properties thereof.
BACKGROUND TECHNIQUES
Generally, in an electron beam-irradiating reaction apparatus, thermoelectrons are generated by using a filament provided at an inner end portion of an accelerating tube which provides an electron accelerator, and an electron beam is formed by accelerating the thermoelectrons in the accelerating tube, followed by irradiation of the electron beam to a desired object through a scanning tube connected to the accelerating tube. An electron beam release window, which is formed at an end portion of the scanning tube from which an electron beam is released, includes a metal window foil attached thereto for shielding the inside of the scanning tube in a vacuum state from the outside. When an electron beam passes through the metal window foil, a part of its energy is converted to thermal energy, to thereby heat the metal window foil. Therefore, a cooling gas is blown against the metal window foil to cool the foil to a temperature such that no deterioration of the foil occurs. The metal window foil, in many cases, is made of titanium or an alloy thereof, and has a thickness of several to several tens &mgr;m. When such a foil is used, its temperature in a cooled condition should be 200 to 400° C.
A typical example of an electron beam-irradiating reaction apparatus is an electron beam gas treatment apparatus in which an electron beam such as that mentioned above is irradiated to a gas such as a combustion gas from a boiler, which contains sulfur oxides or nitrogen oxides, or an exhaust gas discharged from a painting booth, which contains a volatile organic compound, to thereby remove harmful substances such as nitrogen oxides or sulfur oxides contained in the gas. In this gas treatment apparatus, an electron beam irradiation device is set to a position such that an electron beam release window of a scanning tube thereof is in alignment with an electron beam receiving window provided in a side wall of an electron beam reaction device (generally a part of an exhaust gas duct) which allows passage of an exhaust gas therethrough. An electron beam is irradiated through the electron beam release window and the electron beam receiving window to a gas passed through the reaction device.
FIG. 1
shows an example of a conventional electron beam gas treatment apparatus, especially an end portion of a scanning tube 12 and an area in the vicinity thereof (apparatuses similar to that of
FIG. 1
are disclosed in
FIG. 1
of Unexamined Japanese Patent Application Public Disclosure No. 51-96998,
FIG. 2
of Unexamined Japanese Patent Application Public Disclosure No. 52-37553,
FIG. 1
of Unexamined Japanese Patent Application Public Disclosure No. 52-149596,
FIGS. 1 and 2
of Unexamined Japanese Patent Application Public Disclosure No. 53-75163,
FIG. 1
of Unexamined Japanese Utility Model Application Public Disclosure No. 55-107228,
FIGS. 1 and 4
of Unexamined Japanese Utility Model Application Public Disclosure No. 63-168899,
FIGS. 1 and 7
of Unexamined Japanese Utility Model Application Public Disclosure No. 63-168900 and
FIG. 5
of Unexamined Japanese Patent Application Public Disclosure No. 8-166498).
The scanning tube
12
includes an electron beam release window
13
formed at an end portion thereof. A flange
36
is formed along the outer periphery of the end portion of the scanning tube
12
. A metal window foil
14
is fixedly held between the flange
36
and a holding plate
16
for maintaining an internal vacuum of the scanning tube
12
.
An electron beam reaction apparatus (an exhaust gas duct in the case of treatment of an exhaust gas from a boiler)
18
, through which a gas irradiated with an electron beam flows, includes an electron beam receiving window
15
formed in a side wall thereof for receiving an electron beam. A (secondary) metal window foil
34
is provided by means of holding plates
53
and
56
so as to hermetically close the electron beam receiving window.
An electron beam is irradiated into the electron beam reaction device through the metal window foils
14
and
34
. As mentioned above, the metal window foils absorb energy of the electron beam and are heated. As a result, it is necessary to cool the metal window foils to a temperature such that no lowering of the strength of the foils occurs. Therefore, in this apparatus, cooling gas nozzle members
51
and
57
, which include gas slits (or blow openings)
52
and
58
for blowing a cooling gas against the respective metal window foils, are provided in a space between the metal window foils
14
and
34
.
In this case, however, a cooling gas which has been blown against the metal window foils
14
and
34
is diffused into the environment giving rise to the following problems. That is, the cooling gas receives the irradiation of the electron beam when passing through a region where the electron beam passes. When air is used as the cooling gas, ozone and nitrogen oxides (which are harmful to humans and cause corrosion of metallic materials) are produced due to the irradiation of an electron beam. When an inert gas such as nitrogen is used as the cooling gas, although production of ozone and nitrogen oxides in the cooling gas can be prevented, the inert gas after use is subjected to disposal. This is highly disadvantageous in terms of economy.
FIG. 2
shows another example of a conventional electron beam gas treatment apparatus (apparatuses similar to that of
FIG. 2
are disclosed in
FIGS. 3 and 5
of Unexamined Japanese Patent Application Public Disclosure No. 8-166497 and
FIG. 5
of Unexamined Japanese Patent Application Public Disclosure No. 9-171098). The arrangement of the apparatus of
FIG. 2
is substantially the same as that of the apparatus of
FIG. 1
, except that the cooling gas nozzle assembly is changed. The same elements as those shown in
FIG. 1
are designated by the same reference numerals, and an explanation thereof is omitted.
In this apparatus, in order to solve the above-mentioned problems, the cooling gas nozzle assembly is formed integrally with a cooling gas nozzle member
61
for the primary metal window foil
14
, a cooling gas nozzle member
67
for the secondary metal window foil
34
, and exhaust gas tubular passages
65
and
69
disposed so as to face gas slits
62
and
68
of the respective nozzle members. Thus, a cooling gas is supplied and discharged through the tubular passages hermetically sealed from the atmosphere.
With this arrangement, a cooling gas which has passed through the region of passage of the electron beam is not diffused into the atmosphere and can be recovered. Therefore, when air is used as the cooling gas, it is possible to introduce the cooling gas recovered from a discharge opening into a device where the gas is made harmless. Further, it is also possible to use an inert gas such as nitrogen as the cooling gas in a circulative manner.
FIG. 3
shows another example of a conventional electron beam gas treatment apparatus (apparatuses similar to that of
FIG. 3
are disclosed in
FIG. 4
of Unexamined Japanese Patent Application Public Disclosure No. 52-37553,
FIG. 2
of Unexamined Japanese Patent Application Public Disclosure No. 52-149596,
FIGS. 3 and 4
of Unexamined Japanese Patent Application Public Disclosure No. 53-21397,
FIG. 2
of Unexamined Japanese Patent Application Public Disclosure No. 53-46598,
FIGS. 1 and 3
of Unexamined Japanese Utility Model Application Public Disclosure No. 5-30800 and
FIG. 2
of Unexamined Japanese Utility Model Application Public Disclosure No. 6-51900).
In the apparatus of
FIG. 3
, as in the case of
FIG. 2
, a sealable space is formed between the primary metal window foil
14
and the secondary metal window foil
34
. However, in the apparatus of
FIG. 3
, a single cooling nozzle member
71
and a single exhaust gas tubular passage
73
are disposed adjacent to each other on one side of the sealable space. A

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