Chemistry: electrical and wave energy – Processes and products – Processes of treating materials by wave energy
Patent
1991-08-21
1993-09-14
Niebling, John
Chemistry: electrical and wave energy
Processes and products
Processes of treating materials by wave energy
2041582, B01D 5300
Patent
active
052445526
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to a process for waste gas treatment, particularly to a process and an apparatus for desulfurization and/or denitration of waste gas by multi-stage electron beam irradiation.
2. Background Art
There has heretofore been developed a process for waste gas treatment, which comprises introducing a waste gas containing sulfur oxides and/or nitrogen oxides into an electron beam irradiation chamber and irradiating the waste gas with an electron beam, adding ammonia to the waste gas before and/or after the electron beam irradiation, removing the resulting by-product by means of a dust collector, and discharging the waste gas into the atmosphere. Further, improvements for the above process have been studied. With respect to the process for waste gas treatment using a multi-stage electron beam irradiation apparatus, a process using a plurality of irradiation units is proposed in "Process and Apparatus for Desulfurization and Denitration of Waste Gas by Multi-stage Electron Beam Irradiation" (Japanese Patent Publication No. 40052/1984). The document makes no theoretical description as to why the multi-stage irradiation provides increased desulfurization and denitration rates. That is, the document makes no mention of the distance of two neighboring electron beam generators in an operational plant. Similarly, no mention is made of the effect of non-irradiation zone(s), in "Process for Selectively or Simultaneously Separating Harmful Substances from Waste Gas by Electron Beam Irradiation" (Japanese Patent Publication No. 501142/1988).
As described above, there has heretofore been known a process for waste gas treatment using a plurality of electron beam generators. However, it has not been known with regard to the process exactly how the multiple electron beam generators should be arranged. For example, the residence time in the non-irradiation zone(s) has been considered to take several seconds to several tens of seconds as described hereinafter. Therefore, it has been assumed that a concrete building which shields the irradiation chamber and the electron beam generators would have to be very big.
Hence, it is an object of the present invention to set the conditions for arranging a plurality of electron beam generators and thereby to provide a multi-stage electron beam irradiation apparatus capable of effecting electron beam irradiation efficiently and treating a waste gas economically as well as a process for waste gas treatment using said apparatus.
DISCLOSURE OF INVENTION
In order to achieve the above object, the present invention provides a multi-stage electron beam irradiation apparatus for waste gas treatment, comprising an electron beam irradiation chamber accommodating a plurality of electron beam generators, wherein the acceleration voltage of the electron beam is 300-3,000 KV, the flow velocity of said waste gas is not more than 30 m/sec and the temperature of said waste gas to be treated is not lower than the dew point but not higher than 100.degree. C., and the center-to-center distance between two neighboring electron beam generators is not shorter than distance X calculated from the following formula: beam generators, direction of this distance intersects the flow direction of waste gas and the direction opposite thereto; the distance refers to a distance up to a point where substantially no electron beam reaction takes place and varies depending upon the acceleration voltage of electron beam generators, the temperature of waste gas and the composition of waste gas) is about 0.01-0.5 seconds).
In the above formula, t is 0.1-0.5 and refers to a residence time (sec.) at a site (non-irradiation zone) where substantially no electron beam reaction takes place. This value is based on the result of two-stage irradiation test shown in Examples.
In order to achieve another object, the present invention provides a process for waste gas treatment by electron beam irradiation, which comprises introducing a waste gas containing sulfur oxides and/or nitrogen oxi
REFERENCES:
patent: 4435260 (1984-03-01), Koichi et al.
Japanese Patent Abstract 63-302924, Sep. 12, 1988, "Electron Beam Irradiation Treatment Device for Exhause Gas", Akihiko Maezawa.
Aoki Shinji
Izutsu Masahiro
Namba Hideki
Okamoto Kyoichi
Sato Shoichi
Delacroix-Muirheid C.
Ebara Corporation
Niebling John
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