JPS5934412B2 - Ozone deodorization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for deodorizing malodorous exhaust gas using ozone.

Conventionally, in the deodorizing method by mixing ozone in the vapor phase with malodorous exhaust gas, the reaction rate is low. For example, if ozone is injected and mixed at a ratio of 30% to the amount of malodorous substances in the exhaust gas, 50% Moreover, even when the ozone injection ratio was increased to 3 or higher, the hydrogen sulfide decomposition rate of 50% did not change.

Therefore, the present invention investigated the reactivity of various malodorous substances in malodorous exhaust gas with ozone, and found that the relationship between reaction rate and molar ratio (molar ratio between malodorous substances and ozone) over a wide range of the exhaust gas flow path was investigated. We obtained the knowledge that is constant.

Therefore, they came to the conclusion that if ozone is replenished one after another along the flow of malodorous exhaust gas, the overall reaction rate will increase even if the total ozone injection ratio remains constant, and the method of the present invention was completed.

That is, the present invention provides a plurality of ozone injection devices in the flow path of the malodorous exhaust gas, and injects the ozone so that the ratio between the amount of malodorous substances remaining in the malodorous exhaust gas and the amount of ozone at the ozone injection point is constant. The gist of the present invention is an ozone deodorizing method characterized by injecting ozone from an injection device to deodorize malodorous gas.

Hereinafter, the method of the present invention will be explained in more detail using the accompanying drawings.

The accompanying drawings are schematic illustrations showing one embodiment of the method of the present invention.

In the figure, 1 is an ozone contact tank, 2 is a baffle, and 31 to 33 are ozone injection lines.

The foul-smelling exhaust gas that is also introduced into line 4 is first introduced into line 3.
Ozone is injected from 1 and advances through the ozone contact tank 1 while some of the malodorous components are decomposed.

Next, new ozone is injected from line 3□ so that the total amount of remaining ozone and new ozone becomes a constant ratio with the remaining malodorous components.

As a result, the malodorous components continue to decompose, and the ozone contact tank 1
Go inside.

Finally, new ozone is injected from line 33 under the same conditions as line 3□, most of the malodorous components are decomposed, and line 5 is also discharged out of the system as deodorized exhaust gas.

A more specific explanation will be given using hydrogen sulfide as an example of a malodorous substance.

When ozone is injected at a ratio of 30 parts to 1 part of hydrogen sulfide, in the conventional method, 50% of the hydrogen sulfide and 60% of the ozone are decomposed as described above, and even if the ozone injection damage is 3 or more, this decomposition rate remains low. does not change.

However, in the case of the method of the present invention, the first stage (line 3□ in the figure)
), when ozone is injected at a ratio of 30 parts to 1 part hydrogen sulfide,
As mentioned above, since the decomposition rate of hydrogen sulfide and ozone is constant, the residual hydrogen sulfide is (1-I Xo, 5=) 0.5
, the residual ozone is (L-3X0.6=)1.2.

Next, in the second stage (line 3□ in the figure), new ozone is added so that the total amount of residual ozone (1.2 tons) is at a ratio of 3 to 0.5 of residual hydrogen sulfide, that is, 0.3 When new ozone is injected, the decomposition rate of hydrogen sulfide and ozone remains constant, so the remaining hydrogen sulfide is (0,5-0,5X
O,5=)0.25, residual ozone is (1,5-1,5
X0.6=]0.6.

Furthermore, if 0.15% of new ozone is injected in the third stage (line 33 in the figure) under the same conditions as the second stage, the decomposition rate of hydrogen sulfide and ozone is also constant, so the residual hydrogen sulfide will be 0. .125, and the residual ozone is 0.3.

That is, according to the method of the present invention, a total of 3.
When ozone is injected at a rate of 45%, the ozone decomposition rate is 87%.
．． This amounts to 5%.

If you continue this operation, the effect will increase as much as you want, but in practical terms, the limit is about 3 stages.

The above also applies to other malodorous substances such as ammonia, methyl mercaptan, methyl sulfide, and trimethylamine.

As for the ozone injection rate for these malodorous substances, it is sufficient to remove 123 harmful substances as in the case of hydrogen sulfide, but since ammonia has low reactivity with ozone, it is basically removed by pretreatment. Do it like this.

Therefore, it goes without saying that the effect will be further improved if the malodorous substance and the amount of residual ozone are detected at each stage and a constant amount of ozone is always injected.

Further, in the method of the present invention, decomposition proceeds sufficiently at room temperature (20°C, latm), but the decomposition rate is further accelerated at temperatures of 30°C or higher.

In addition, in the conventional method, when ozone was injected at a ratio of 3.45 to 1 hydrogen sulfide, the decomposition rate of hydrogen sulfide remained unchanged at 50% and ozone at 60% at a contact time of 2 to 5 seconds. Residual hydrogen sulfide was 0.5, and residual ozone was 1.49.

From the above, it is clear that according to the method of the present invention, the decomposition of malodorous substances is markedly improved even when the amount of ozone injected is the same as in the conventional method, and that the method of the present invention is an excellent ozone deodorizing method.

[Brief explanation of drawings]

The accompanying drawings are schematic illustrations showing one embodiment of the method of the present invention.

Claims (1)

[Claims] 1 A plurality of ozone injection devices are installed in the flow path of the malodorous exhaust gas, and ozone is injected from the ozone injection device so that the ratio between the amount of odor substances remaining in the malodorous exhaust gas and the amount of ozone at the ozone injection point is constant. An ozone deodorizing method characterized by deodorizing malodorous gas by injecting it.