SU1581360A1 - Method of cleaning waste gases from organic impurities - Google Patents

Abstract

The invention relates to the field of gas cleaning and can be used in the chemical, petrochemical, automotive and other industries. The purpose of the invention is to increase the service life of the catalyst. While maintaining a high degree of purification from organic impurities, the gases are preheated in a heat exchanger, sent to a distributor, from which one stream of exhaust gases is sent to a gas burner preheater, where it is heated by mixing with the combustion products of the fuel gas and the other is passed through a heat exchanger located in the catalyst bed. The stream heated in the heat exchanger is fed to the mixture with the main gas and the resulting gas stream with a temperature of the onset of catalytic oxidation is passed through the catalyst bed, while the temperature difference across the depth of the catalyst is maintained at -35 ° C. The service life of the catalyst was 2.8 years with a degree of purification of about 98%. 1 dw., 2 tab.

Description

The invention relates to the purification of gases and can be used in the chemical, petrochemical and other industries.

The aim of the invention is to increase the service life of the catalyst while maintaining a high degree of purification.

The drawing shows a scheme for implementing the method of thermal catalytic purification of flue gases.

The proposed method is carried out as follows.

Exhaust gases containing toxic substances are preheated in heat exchanger 1, sent to distributor 2, from which one stream of exhaust gases (the ratio of flows depends on the concentration of toxic substances in exhaust gases) is sent to the mixing gas burner heater 3, where is heated by mixing the fuel gas with the combustion products, and the other is passed through a heat exchanger 4 located in the catalyst bed 5. The stream heated in the heat exchanger 4 is fed to mixing with the main stream (heated As a result, the temperature of the formed stream corresponds to the temperature of the onset of catalytic oxidation of toxic substances, and then is passed through the catalyst bed 5. The cleaned gases are sent to the heat exchanger 1, where they give off their heat to the waste gases coming to the purification, and The air duct 6 is removed to the atmosphere or for production.

Example I (prototype).

Exhaust gases containing toluene vapor, on average, 4J5 g / m3, preheated in a heat exchanger up to 180 ° C, are fed to a combustion chamber, where they are mixed with combustion products, resulting in a preheat to the temperature of the onset of catalytic oxidation of toluene (210 ° C) ,

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and passed through a palladium-manganese catalyst cassette. Toluene is oxidized on the catalyst, as a result of which the temperature rises to 350 ° C along the depth of the catalyst. The cleaned gases with a temperature of 350 ° C are sent to a heat exchanger, where they give up their heat to the waste gases that have returned to the purification, and are discharged to the atmosphere. The degree of cleaning at the same time reaches 98%. According to a known method, the temperature drop over the depth of the palladium-manganese catalyst and catalyst P-4 is equal to 140 ° C. Catalyst P-4 contains 0.05 wt.% Palladium on carrier A & Oz. From the operating experience of the thermocatalytic reactor, it was found that by a known method there is a rapid drop in the activity of the output (downstream) catalyst layers, although the input layers still retain activity. The service life of the catalyst 0.9 g

Example 2 (the proposed method).

Exhaust gases containing an average of 4.5 g / m3 of toluene vapor, preheated in heat exchanger 1 to 180 ° C, are sent to stream distributor 2, where they are divided into two streams, one of which is 45% of the total , served in the gas burner mixing heater 3, where it is heated by the combustion gas fuel products, and the other, 55%, is passed through the heat exchanger 4 located in the catalyst bed 5. The flow is heated in the heat exchanger 4 to 240 ° C due to the increase in heat effect toluene oxidation reaction in depth catalyst , is fed to the mixing and cooling with the stream heated by the combustion products, and at 210 ° C (the beginning of the catalytic oxidation of toluene) is passed (the total stream) through a layer of palladium-manganese catalyst 5. The purified gases are sent to the heat exchanger 1, from where they are, giving their the heat of the waste gases returned to the purification is removed through the duct 6 to the atmosphere or for the needs of production. The amount of toluene in the purified gases is 0.01%. The degree of purification is 98.8%.

According to the proposed method, the temperature difference across the depth of the catalyst is 35 ° C.

Example 3. As in Example 2, only catalyst P-4 is used.

The onset temperature of catalytic oxidation is 320 ° C, and the temperature at the outlet of the catalyst is 355 ° C. The temperature difference across the depth of the catalyst is 35 ° C.

Data on the distribution of the waste gas flows depending on the toluene concentration are given in Table. one.

Table 1

five

The stream entering through the gas burner mixing heater.

The flow coming through the heat exchanger located in the catalyst bed.

Data on the service life of the catalyst P-4 and thermocatalytic reactor (apparatus) when working on the known and proposed methods are given in table. 2

Table 2

Indicators

Way

The proposed method allows to increase the service life of the catalyst by 1.4 times while maintaining a high degree of gas purification.

Claims (1)

Invention Formula The method of purification of waste gases from organic impurities, including heating the gases by mixing with the products of their combustion and contacting with the catalyst layer, characterized in that, in order to increase the service life of the catalyst, the initial combustion products are divided into two streams, the first of which contacts through the wall with a layer of catalyst, maintaining the temperature difference in the depth of the layer is equal to 35 ° C, after which it is mixed with the second stream and fed into the catalyst bed. Waste gases