RU2234971C2 - Method of neutralizing ozone in gas media - Google Patents

Abstract

FIELD: gas treatment.

SUBSTANCE: invention relates to using gas electrochemistry for neutralization of residual ozone. In particular, ozone is affected by light emission in high-frequency electric field using cold plasma for 0.5 to 1.0 sec. Gas mixture is then passed through carbon filter.

EFFECT: reduced power inputs, avoided use of catalysts, and simplified structure of equipment.

2 cl, 2 dwg

Description

The invention relates to the field of gas electrochemistry, in particular to methods for the decomposition of ozone in the spent mixture after ozonation of potable and industrial water, industrial wastewater, and can also be used in chemical, pharmaceutical, metallurgical, pulp and paper and other industries carrying out the purification of gas mixtures from ozone.

A known catalytic method for the purification of gases from ozone on a catalyst consisting of platinum or palladium on active alumina, the process is conducted at a temperature of from 95 to 130 ° C and a gas volume velocity of 9000-30000 h [1].

The disadvantages of this method are the use of expensive rare metals and heating the catalyst with electric heaters that consume a large amount of energy (35 W / m ³ ). The process is inertial; it takes a considerable time (up to several hours) to reach the thermal mode of the device.

A known method of processing spent ozone in order to neutralize it using electricity without electric heaters. Gases containing spent ozone are passed over the photocatalyst when exposed to light catalyst in an electric field. The photocatalyst produces radiation of a certain wavelength, sufficient for the decomposition of ozone. Light radiation in an electric field is obtained by a candle or spark converter. To increase the contact time, labyrinth channels are used [2].

The disadvantage of this method is the complexity of manufacturing a device that implements it. With small-scale production, the price of this device will be prohibitive.

The aim of the invention is: a significant reduction in energy consumption per 1 m ^{3 of} treated gas, the rejection of the use of rare metals (catalysts) and the structural simplicity of devices that implement the proposed method.

This goal is achieved by the fact that in the known method of neutralizing ozone in gas mixtures, which consists in treating ozone with light radiation in an electric field, the ozone is processed in a high-frequency electric field with cold plasma. To completely neutralize ozone, the treated gas is passed through a charcoal filter.

The proposed method is implemented on the device shown in the drawings. In FIG. 1 shows a longitudinal section, FIG. 2 is a cross section in the area of the partition.

The device consists of a chamber 1 with an inlet pipe 2 for supplying the spent ozone-gas mixture. In the chamber 1, a heat-resistant partition 3 with a window 4 is installed, forming a reaction zone. Candle 5 and electrode 6 with electric leads 7 constitute a working element of the electrical part of the device, which creates a channel of high-frequency electric discharge, which is a source of cold plasma. The carbon filter, consisting of a housing 8 loaded with coal 9, is connected via a pipe 10 to a chamber 1 from which a gas mixture processed in an electric field is supplied. After the filter through the pipe 11, the gas mixture neutralized by the proposed method is discharged into the environment.

The method of neutralizing ozone is as follows.

From the entrance side, the partition 3 has a rectangular window 4 with a height of 10 mm and a length of 30 ... 50 mm. The electrode end 6 is located on one of the small sides of the window, and the flat end of the candle 5 with a diameter of 10 mm is located on the other. Between the electrode and the candle, a channel of high-frequency electric discharge with a cold plasma (T ~ 5000K) with a diameter of 10 mm is created and air is ionized.

It is known from chemical physics that the dissociation of an oxygen molecule occurs when it collides with an electron with an energy of (5.084 eV), i.e. O ₂ + e (5.084 eV) → O + O followed by the formation of ozone O ₂ + O → O ₃ . Dissociation of the ozone molecule occurs when it collides with an electron with an energy of (2.26 eV), i.e. O ₃ + e (2.26 eV) → O ₂ + O followed by the formation of oxygen O + O → O ₂ . Ozone is thermally unstable, rapid decay occurs at a temperature of 100 ° C. The lifetime of O ₃ at a temperature of 200 ° C is approximately one second [3].

The residence time of the treated ozone-gas mixture in the chamber is preferably 0.5-1.0 s. This time can be obtained, for example, by selecting the window length and camera volume.

Part of the ozone dissociates from collisions with electrons with energy (2.26 eV <e <5.0 eV), another part of the ozone decays due to thermal heating.

The radicals formed by oxygen O in the cylindrical part outside the window are combined into oxygen molecules O + O → O ₂ . A “slip” of the oxygen radical O through the cylindrical part of chamber 1 is theoretically possible, therefore, to guarantee complete neutralization of ozone, chamber 1 is connected by a pipe 10 to the filter housing 8 filled with ordinary coal 9, where the coal is oxidized by oxygen radicals O.

The ozone neutralization process according to the proposed method can be regulated and optimized. For example, with a low concentration of residual ozone, it is possible to reduce the discharge energy in a high-frequency electric field or increase the flow rate of the treated gas. Optimal parameters are established based on the results of monitoring residual ozone.

Equipment designed to implement the method is compact, convenient to operate and does not require large financial costs.

Used sources

1. RF patent No. 1603562 (c. No. 4433126/26 of 05/30/88). The method of purification of gases from ozone, IPC B 01 D 53/66.

2. Japan patent No. 4-5485 (z. No. 62-139860 from 05.06.87). The method of processing spent ozone. IPC B 01 D 53/36.

3. Chemical encyclopedia. Scientific publishing house "Big Russian Encyclopedia", M., 1992, v.3, p.332-333.

Claims (2)

1. The method of neutralizing ozone in gas mixtures, which consists in treating ozone with light radiation in an electric field, characterized in that the treatment is carried out in a high-frequency electric field with cold plasma for 0.5-1.0 s. 2. The method according to claim 1, characterized in that the treated gas is passed through a carbon filter.

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