JPS59222213A - Treatment of waste gas - Google Patents

Abstract

PURPOSE:To remove simultaneously NOx and/or SOx as a solid product by irradiating ionizing radiation to a waste gas which is added with ozone and an alkaline substance beforehand. CONSTITUTION:The waste gas contg. NOx and/or SOx is introduced into a reactor 4 from a discharge source 1, and irradiated with an electron beam from an electron beam irradiating apparatus 3 arranged in an irradiation chamber 2. A strongly oxidizing active seed is formed therein, and NOx and SOx are oxidized by the active seed finally to nitric acid and sulfuric acid mists which are collected by a dust collector 7. At this time, oxidation can be promoted by adding O3 from an ozone adding port 5 provided on this side of an inlet of the irradiation chamber. The radical formation is promoted by adding an alkaline substance such as ammonia, and the formed mists are also neutralized and removed as a solid product.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating exhaust gas. In more detail (]), the present invention uses nitrogen oxides (hereinafter sometimes abbreviated as "NOx") and/or sulfur oxides (hereinafter sometimes abbreviated as "SOx"). The present invention relates to a method for treating exhaust gas by adding ozone and alkaline substances to exhaust gas and irradiating it with ionizing radiation.

1) Description of the Prior Art JP-A-50-57064 discloses a method for treating exhaust gas by electron beam irradiation, which improves the efficiency of denitrification and desulfurization by adding an alkaline substance such as ammonia to the exhaust gas. However, this conventional technique is particularly difficult to use when the concentration of N is high.
Ox and/or gases have problems that should be improved in terms of denitrification and desulfurization efficiency of four gases including SOX (for example, coal combustion exhaust gas, etc.).

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel exhaust gas treatment method that overcomes the problems of the prior art.

A specific object of the present invention is to add ozone and alkaline substances to exhaust gas containing NOx and/or SOx (2) 7JO and irradiate the ionizing beam in this state with 1-1 nitrogen oxides and/or sulfur oxides. It is an object of the present invention to provide a method for treating exhaust gases that can simultaneously remove them as solid products.

Other objects and advantages of the invention will become more apparent below in conjunction with the accompanying drawings.

The structure of the present invention will be explained with reference to FIG. 1 (not shown).

Figure 1 shows the case in which ozone (03"l) and alkaline substances are not added. In Figure 1, N (Jx and/or
Alternatively, the exhaust gas containing SOx Y is placed in the irradiation chamber λ and is irradiated with an electron beam from a moxibustion electron beam irradiation device. Here, the mixed gas of N2, 0□, 1+2C), which is the main component of the exhaust gas, generates highly oxidizing active species such as 0 atoms, UII radicals, +(02 radicals, etc.) through radiation chemical reactions, and these active species Depending on the species, N (Jx and SOx) are oxidized and finally become nitric acid and first acid mist ((1) and (2) below) (3) The mist thus generated is collected by an electrostatic precipitator, etc. Dust equipment J
is collected and removed from the exhaust gas. In this way, NOx and SOx are removed and the purified exhaust gas is discharged into the atmosphere by the blower φ.

By adding ozone from the ozone addition port 5 provided before entering the irradiation chamber in Fig. 1, the oxidation reaction of (]+ and (2+) can be accelerated.
x and 0. The unique feature of this method is that it not only involves a simple oxidation reaction with the electron beam, but also active species (radicals, etc.) generated by electron beam irradiation that also contribute to the reaction. This second addition port is sure to
It must be located in front of the irradiation chamber. The amount of ozone added depends on the density of N□x to be treated and the amount of KSOx, but it is sufficient that it is less than the sum of the NOx concentration and SOx concentration. However, if the ozone concentration is too high, there is a risk of secondary pollution caused by ozone (4), and if too much force is used, the effect of ozone addition may not be sufficiently achieved. For this reason, it is desirable that the amount of ozone added be about 1 to 1 - I+ of the NOx and 3Hx concentrations to be treated. As shown in Figure 1, by adding Al 100 from the addition port A, (11.

Generated by (2), Tamist etc.? It can be neutralized and removed as a solid product. In the embodiment of the present invention, ammonia gas is added as an alkaline substance, but in this case, as is already known, ammonia generates highly reactive radicals when irradiated with an electron beam, so it is difficult to react with IJi radiation chemical reactions. To promote.

Since it is a gas phase reaction, it is particularly effective in that the reaction rate is high. In addition, this addition [additionally, the above-mentioned radiation chemical reaction occurs, or the electron beam irradiation accelerates the production rate of one particle and improves the collection efficiency due to charging, which improves the dust collection efficiency. It is desirable to install it in front of the irradiation room because it has the advantage of being visible.

If ammonia gas is used, it is desirable that the addition port be located just before the irradiation chamber (5) to minimize the decomposition of ozone by ammonia.

The structure and effects of the present invention will be explained more specifically by referring to examples and reference examples.

Examples 1-2 NO (60 (1 ppm)-S) simulated lack of coal combustion exhaust gas
O2 (1000ppm) - 120 (F3%) -0
2(i[lq et al.)-N2(bal ance
) was added with ozone in an amount to give a concentration of 270 pr+m and ammonia in an amount to give a concentration of 2600 pp+n, and then irradiated with an IMeV electron beam at 120°C, and the degrees of NOx and SO2 at this time were measured. 1 piece.

The results are shown in Table 1. The NOx concentration is 600 ppm to 65 ppm with 4 Mrad irradiation.
0. The concentration also decreased from 10 [1 [] ppm to 50 ppm or less, from about 1/10 to 1/20 of the initial a degree.

1 0.67 150 <502
4.0 65 <50 (6) Examples 3-5. Reference Examples 1 to 2 Under the same conditions as Examples 1 and 2, electron beam irradiation was performed 7 times, and the amount of solid product collected in an electrostatic precipitator was measured at a certain time, and this product was identified. child. The results are not shown in Examples 5 to 5 of Table 2.

Similar measurements were conducted for the same mixed gas without the addition of ozone. The results are shown in Reference Examples 1 and 2 in Table 6.

As can be seen from these tables, the amount of collected solid product (a mixture of ammonium sulfate and ammonium nitrate) increases as the irradiation dose increases, and the amount of collected solid product (mixture of ammonium sulfate and ammonium nitrate) increases as the irradiation dose increases; It can be seen that the amount is increasing. for example.

Example 5 shows an increase of about 50% compared to Reference Example 2.

(7) Table 2 RoOO 00

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing one embodiment of the present invention. C8)

Claims (1)

[Claims] 1) Exhaust gas containing nitrogen oxides and/or sulfur oxides 7 is irradiated with ionizing radiation in a state in which ozone and an alkaline substance Z are added to produce nitrogen oxides and/or sulfur oxides in solid form. A method of treating exhaust gas that consists of simultaneously removing it as a gas. 2) The method according to claim 1, wherein the amount of ozone added is equal to or less than the sum of the degrees of nitrogen oxides and sulfur oxides. 2) The method according to claim 1, wherein the alkaline substance added is in an amount necessary to neutralize nitrogen oxides and nitric acid and sulfur oxides as sulfuric acid.