JPS6034481B2 - Ozone decomposition method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel ozone decomposition method and apparatus.

Ozone (03) is a gas that has oxygen as a generating group and has the second highest oxidizing power next to fluorine, and is also highly toxic, so it is necessary to decompose excess ozone to prevent secondary pollution.

There are various methods for decomposing ozone gas, but they can be roughly divided into the following four types.

a Oxidation method (or reduction method) The active oxygen atoms of ozone are oxidized and reduced with other substances (including the active oxygen atoms of ozone, also called oxygen of the generating group). is separated, leaving only oxygen.

b. Adsorption method There are methods that adsorb ozone (03) itself, and methods that gradually react while adsorbing it.

For example, water can dissolve 03 gas 15 times more than oxygen (see Table 1), and activated carbon gradually combines with carbon while adsorbing 03 gas, becoming carbon gas. C120
3→C02102 Since this reaction formula is an exothermic reaction, it is also used for cooling, and is generally used by soaking activated carbon in a decomposition tank with water or by adding water dropwise.

Therefore, the absorption effect of 03 decreases (activated carbon absorbs more than water).

Table 1 Dissolution of Ozone/Oxygen in Water (c) Pyrolysis Method Pyrolysis method is because ozone 03 itself is unstable, so it easily decomposes when heated to form Phantom 3 → No. 2.

Although this method can be used satisfactorily even with high concentrations of 03,
Ozone itself has strong oxidizing power and high temperatures (over 300℃...
(varies depending on concentration, flow rate, and flow velocity), heat sources such as heaters are severely corroded, and extra fuel, electricity, etc. are required. d Natural decomposition method 03 is unstable, so even if it is left alone, it will react with other 03 and become oxygen.

(203→2) It has the advantage of not being expensive, but it takes time (depending on the concentration and temperature, but takes several hours or more at concentrations in the industrial range) and cannot be used industrially.

Of the four types mentioned above, those that can be actually used industrially are the oxidation (reduction) method (a) and the adsorption method (b). However, a oxidation (reduction)
The process is a reaction in which ozone 03 becomes stable oxygen 02 by giving or receiving oxygen, but since there is a limit to the amount of substances that can participate in the reaction, the effect gradually decreases and eventually decomposes. It becomes unusable and needs to be replaced. This also applies to the adsorption type, as the ozone absorption and decomposition effect gradually decreases, requiring replacement.

Therefore, the present inventors conducted various experiments and research with the aim of providing an ozone decomposition method or apparatus that can satisfactorily decompose ozone without reducing efficiency over a long period of time. They attempted to decompose ozone using easily available cast iron chips or cutting dust generated during factory work, and in doing so, they sprinkled water on the chips or cutting dust to promote oxidation when left in the air. It was unexpectedly discovered that ozone can be decomposed over a long period of time without any loss in efficiency when used in the presence of water, such as by immersing it in water or by immersing it in water. What is actually produced by applying water to the cast iron chips or chips is iron oxide [Fe0,
Iron hydroxide [Fe(OH)2, F
e(OH)3], and as a result, the present invention was achieved. Thus, according to the present invention, by decomposing ozone using iron hydroxide, in particular, by decomposing ozone using iron hydroxide obtained by reacting water with cast iron chips or chips, the above-mentioned It was discovered that the purpose could be achieved. The present invention will be described in more detail with respect to one embodiment thereof.

Regarding the system diagram of ozone generation and decomposition shown in Figure 1 of the drawing, 21 is an air compressor, 22 is an air dryer, 2
3 indicates an ozonizer, that is, an ozone generator. 24 is an iron hydroxide ozonolyzer filled with iron hydroxide and has a structure as described later, and 25 is an activated carbon ozonolyzer filled with activated carbon.

That is, in this system diagram, air from an air compressor 21 is dried in a dryer 22 and sent to an ozonizer 23, and the ozone generated here is first decomposed in an ozone decomposer 24 that uses iron hydroxide. This air is then passed through an activated carbon ozonolyzer 25 before being discharged to the atmosphere. The concentration is measured at a point 26 exiting the ozonizer 23. Now, regarding the equipment shown in this system diagram, ozone generation,
I did a disassembly test.

The amount of ozone generated by the ozonizer 23 is 10 to 1 spot per hour, and the concentration is several thousand to 10,000 ppm'vol, which is a total of 2
Tested over 00 field hours. The iron hydroxide used in this case was made by sprinkling cast iron chips or chips with water in the form of mist or droplets, but it can also be obtained satisfactorily by immersing them in water. Incidentally, the size of these chips is usually about 1 side thick, about 3 feet long, and about 4 feet wide on average. The decomposition state test used approximately 15 kg of iron hydroxide and approximately 17 kg of activated carbon, and the ozone concentration when released into the atmosphere was measured by humans observing the pungent odor characteristic of ozone, but the human nose is sensitive to ozone. We took advantage of the fact that it is sensitive and can confirm down to a minimum of 0.01 ppm/vol.

In other words, by checking the irritating odor, it is possible to detect a concentration of several thousand to one ppm'
This is because if the vol changes to 0.01 ppm/vol, it can be considered that it has been almost completely decomposed. (There was no irritating odor at all.) Also, in the activated carbon ozonolyzer, which is located next to the iron hydroxide ozonolyzer, windows were installed here and there to observe the process of the activated carbon changing from black to white when it absorbed ozone due to its characteristics. Activated carbon, which caused a white change when ozone was generated at a rate of 10 to 1 h/h, did not change at all.

Activated carbon 17k9 requires 10-15 for complete whitening.
With ozone/g/h, it takes about 100 to 150 hours, but even after 200 field hours, I could not see any activated carbon, which was confirmed to be slightly white.

In other words, ozone was almost completely decomposed by iron hydroxide without using activated carbon.

Furthermore, after testing for 200 hours (approximately 2 years due to intermittent testing), almost no change in iron hydroxide was observed.

It has thus been shown that iron hydroxide can decompose ozone over a long period of time without reducing efficiency. During the experiment, 2 to 3 hours after the start of the experiment, the temperature difference between the room temperature and the outer wall of the iron hydroxide decomposer was about 10 qo, and the outer wall of the decomposer was higher, so it is certain that an internal thermal reaction was involved. .

Ozone generation is an endothermic reaction and decomposition is an exothermic reaction.
yK approx. 2←--→3 5 heat absorption, e heat generation, eK k = 34.1 Kcal'mol Therefore, at an ozone decomposition amount of 10 to 15 g/h, the calorific value is 7.1 to 10.7 Kcal/h (8 .3~12.4W)
Considering the natural heat radiation of the decomposer or the heat radiation to the ozone-containing air, the temperature rise in the decomposer itself is thought to be roughly the same as the heat generated by ozone decomposition.

In addition, when cast iron is used instead of iron hydroxide as a decomposition agent, the carbon content is extremely high at 2 to 4% in the case of cast iron, compared to 0 to 0.8% in pure iron and carbon steel, and this carbon is also absorbed by ozone. It seems that it affects the decomposition reaction, albeit gradually.

The reaction of iron hydroxide/carbon with ozone 03 can be considered as follows.

'a' is e (OH) 2003 → Fe2030 is LO10
2'b' is e (OH) 314031 Fe203 10th day 2
01302 [c} Nuichi no 2 [d} C+203→C0
3002 {e'Fe(〇H)20.

3 → Fe 10th 20th Gen mix female total connection field; Ki... (el)
．． ...(e2) [f1 is e(〇H) 30.

3 → ga e ten ga 20 tenuki shunmei total 397 papers... (fl
). ...(f2) (Note) 'e} and 'f} can be rewritten as follows.

(e') {Fe(OH) 20 places 1 Fe(OH) 20...
(ei) L group e's H) 20 zugae's H) 3gee+nu...
(e2) (f') is e(〇H) 3003 → is e(〇H
) 20th 20th Kei Jugen...(fi) is e(〇H)3 Jugen 3 →
is e (〇H) 3 Juku Kei... (f2) The reactions are above, but the explanation for each is [a} Hydroxide 1st
Ozone [03] directly reacts with iron [Fe(OH)2],
When iron oxide is produced'b} Ferric hydroxide [Fe(OH
) When ozone [03] immediately reacts with 3] to form iron oxide 'c - When iron hydroxide acts as a catalyst for ozone When carbon [C] in cast iron and ozone 3] react (e') Ferrous hydroxide and ozone react to produce iron and water, and iron and water react to form iron hydroxide; (ei) is a case in which ferrous hydroxide is produced. As a result, it becomes a catalyst.

(e2) produces ferric hydroxide and iron. (f') In the case where ferric hydroxide and ozone react to produce iron and water, the iron and water react to form iron hydroxide, and (fi) is the case where ferrous hydroxide and ozone react. Produces water, (f2) produces ferric hydroxide,
As a result, it becomes a catalyst.

By the way, after the test, I dismantled the disassembly device and examined it.
Since there was no change in color etc. compared to before the experiment,
It is thought that it acts as a catalyst for [c}, (ei), and (f2) or as a result.

However, compared to activated carbon, etc., there is no risk of ignition, and there is no need to replace it, so it is considered to be extremely effective.

Thus, when decomposing ozone using the method of the present invention using iron hydroxide, especially iron hydroxide obtained by reacting water with cast iron chips or chips, there is no need for long-term conversion, and there is no need for ignition. It is extremely economical and effective because it can be carried out without any problems, and it uses raw materials that can be obtained at virtually no cost.

In the present invention, the iron hydroxide is particularly referred to as cast iron chips or cutting dust treated with water.
Iron hydroxide is not limited to cast iron, and iron hydroxide can be obtained from other steel materials as well, so it goes without saying that the use of iron hydroxide obtained from other materials also falls within the scope of the present invention.

Another object of the present invention is to provide an apparatus suitable for carrying out a method of decomposing ozone using iron hydroxide.
It consists of a decomposition cylinder whose interior is filled with iron hydroxide, and one or several donut-shaped rings are provided inside the cylinder, or iron hydroxide filled parts and spaces are provided alternately in all directions of the axis. It has been found that an ozone decomposition device comprising a ring with a wire mesh at the boundary achieves this object. To explain in more detail the embodiment of the ozone decomposition apparatus according to the present invention shown in the drawings, the horizontally long cylindrical ozone decomposition apparatus shown in FIG. It has an outlet side cap 8 at both ends and a chest 6 in the center connected to both caps 1 and 8 by flanges 2, 2' and 7, 7', respectively.

Rings 3, 3' having wire meshes 4, 4' inside are attached to the flanges 2', 7' at both ends of the body 6. Several donut-shaped rings 5 are attached to the inside of the chest 6 at appropriate locations between the wire meshes 4, 4, and are in close contact with the inner wall. The body 6 is filled with a required amount of iron hydroxide 11, which preferably consists of cast iron chips or chips soaked in water or dripped with water. In the drawing, iron hydroxide 11 is shown as a black dot for convenience. When gas containing ozone is introduced from the inlet, this gas passes through the inlet cap 1, wire mesh 4, and enters the chest 6 filled with iron hydroxide 11, where it comes into contact with the iron hydroxide 11 and decomposes the ozone. . At this time, the gas flows in a flow path 9 by means of several rings 5 installed at appropriate locations, approximately equally spaced in the figure. In other words, the gas which normally flows easily along the inner wall surface of the same part 8 is forcibly changed in its flow path by the ring 5, so that it also flows to the center, making it easier to come into contact with the iron hydroxide 11 widely filled in the body. Become. The gas thus decomposed in contact with the iron hydroxide 11 in the body 6 is discharged through the outlet side cap 3. Thus, when this device is used, the ozone-containing gas and iron hydroxide come into good contact, and the ozone decomposition efficiency can be greatly improved. FIG. 3 shows an ozone decomposition apparatus according to another embodiment of the present invention, and parts common to those in FIG. 2 are designated by common symbols. In this case, the body 6 is provided with iron hydroxide filling portions 12 filled with iron hydroxide 11 and spaces 13 not filled with iron hydroxide, alternately in the axial direction. A wire mesh ring 10 is provided at the border. In reality, this space 13 is formed into a hollow cylindrical shape with two ends of the ring 10 having a wire mesh 14 on the inside and the outer diameter of which is in close contact with the inner wall of the cylinder. The length of this space 13 in all axial directions is the length of the iron hydroxide filling part 12.
It is shorter than that of . When an ozone-containing gas is passed through such an ozone decomposition device, this gas passes through the iron hydroxide filling section 12 and the space section 13 which are separated by the wire mesh ring 10.
and alternately.

This gas tends to flow toward the center like the flow path 9, which is the same as in the case of FIG. 2, but especially in the case of FIG. The flow portion 15 is formed, which is effective because the flow path is forced to change to the center and the contact efficiency between the gas and iron hydroxide can be further effectively improved. In this way, when using these two ozone decomposition apparatuses of the present invention, the flow path of the ozone-containing gas can be provided not only on the inner wall of the apparatus but also in the center of the apparatus, thereby preventing contact with the iron hydroxide widely filled inside the apparatus. This makes the decomposition of ozone in the gas more efficient.

As is clear from the above detailed description, the present invention can provide a truly effective ozone decomposition method and apparatus.

[Brief explanation of drawings]

Figure 1 is an ozone generation-decomposition system diagram configured for testing the method of the present invention, Figure 2 is an explanatory diagram of an example of the apparatus of the present invention, and Figure 3 is an illustration of another example of the same apparatus. It is a diagram. 1... Ozonized air inlet side cap, 2, 2'...
Flange (inlet side), 3... Ring with wire mesh (inlet side), 3
'...Ring with wire mesh (outlet side), 4...Wire mesh (inlet side), 4
'... Wire mesh (outlet side), 5... Separation change ring, 6... Decomposition cylinder body, 7, 7'... Flange (outlet side), 8... Air outlet side cap, 9... Air flow path, 10... Ring with wire mesh for creating air section, 11... Iron hydroxide, 12...
Iron hydroxide filling part, 13... Space part, 14... Wire mesh, 15
...turbulent flow section, 21... air compressor, 22.
...Air dryer, 23...Ozonizer, 24...
Iron hydroxide ozonolyzer, 25...Activated carbon ozonolyzer, 26...Concentration measurement point. Urushi-z drawing ticket 2 office work 3 drawing

Claims (1)

[Claims] 1. An ozone decomposition method characterized by decomposing ozone using iron hydroxide. 2. The method according to claim 1, characterized in that ozone is decomposed using iron hydroxide obtained by acting water on cast iron chips or chips as the iron hydroxide. 3. Consists of a decomposition cylinder that is horizontally long and filled with iron hydroxide, and one or more rings are provided inside the cylinder, or iron hydroxide filled parts and spaces are arranged alternately in the axial direction. An ozone decomposition device comprising a ring provided in a ring and having a wire mesh on the boundary thereof. 4. The apparatus according to claim 3, wherein iron hydroxide obtained by applying water to cast iron chips or cuttings or cutting powder is used as the iron hydroxide.