SU1701355A1 - Method of cleaning exhaust gases - Google Patents

Abstract

The invention relates to the technology of purification of waste gases from impurities of hydrocarbons and CO used in mechanical engineering, electrical engineering and instrument making and allowing to increase the service life of the catalyst. The granular catalyst is divided into two layers and pushed so that the ratio of the total height of the catalyst layers and the height of the gap is 1: (1-0.05). A catalyst in the form of Raschig rings or rings with partitions of 4–40 mm is used. The gases to be cleaned are passed through the catalyst with a periodic change in the direction of gas movement to the opposite every 10-100 minutes. The process is carried out at a temperature difference in the perpendicular gas flow path at the entrance to the second layer not more than 50 ° C. With an initial concentration of ethyl acetate in air of 0.038 vol.% On a copper-chromium catalyst, a purification degree of 99.9-99.98% is obtained, the maximum temperature in the layer of 530,680 ° C and an increase in the service life of the catalyst to 16-22 months. 1 hp f-ly, 1 tab. SO with

Description

The invention relates to methods for purifying waste gases from impurities of organic substances and CO, and may find application in mechanical engineering, electrical engineering, instrument making and other industries.

The purpose of the invention is to increase the service life of the catalyst.

Example. The catalyst is divided into two parts and pushed so that the ratio of the total height of the catalyst layers and the height of the gap between the layers is 1: (1-0.05).

In order to avoid overheating of the catalyst in the second layer and at the same time

To prevent the formation of frozen sections in the gap between the catalyst layers, you can mix the gas to be cleaned using nanpi Mep, a double segmented grid that realizes the cross-flow of gases from the axis of the reactor to the wall and vice versa.

When cleaning gases containing significant quantities, e, the amount of organic substances (more than 4-5 g / m, the service life of the catalyst is also prolonged by using a granular catalyst in the form of Raschig rings or rings with partitions of 4–40 mm. Using a catalyst such

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shapes and sizes allows to reduce the outer surface in a unit volume of the layer / as compared with the traditionally used in practice catalyst in the form of spheres and cylinders /, and also to increase the longitudinal thermal conductivity of the layer.

The gas containing 0.038% by volume of ethyl acetate in air is fed to the purification system. The linear velocity of the gas in the catalyst bed is 0.6 m / s, the height of the oxide layer of the copper-chromium catalyst is 0.8 m. The gas filtration direction is switched in 30 minutes. The catalyst grain size is 15 mm. The gas passes through the first part of the catalyst bed and, after passing through the gap, enters the second part of the catalyst bed. The temperature difference in the perpendicular to the gas flow section at the inlet to the second part of the layer is maintained at 5 ° C. During the passage of the gas of the second part of the layer, the final oxidation of ethyl acetate to water vapor and carbon dioxide occurs. The maximum temperature in the catalyst bed is 400-550 ° C. The degree of air purification from ethyl acetate is 99.93% by volume. The service life of the catalyst 20 months. The remaining examples are carried out similarly according to the conditions given in the table.

Example 8 is made according to the prior art: ethyl acetate concentration is 0.038% by volume; the time between switching is 30 minutes.

With a higher temperature difference (for example, 100 ° C), the degree of gas purification and time

catalyst services are reduced due to large temperature irregularities. The temperature of the gas filtered along the axis of the reactor will remain higher than that of the walls,

The degree of gas purification from harmful impurities at the outlet of the apparatus will be incomplete, since the oxidation reaction does not take place sufficiently intensively on the cooled near-wall areas.

From these examples, it can be seen that the proposed method makes it possible to increase the service life of the catalyst by 20–25% compared with the prototype.

FORUMAWLAH AND ISLANDS

Claims (2)

1. A method for purifying waste gases from impurities of organic compounds and carbon monoxide by oxidation with oxygen to carbon dioxide and water vapor, including passing the gases to be cleaned through the granular catalyst at elevated temperature and periodically changing the direction of gas movement to the opposite, characterized in service life of the catalyst, it is used in the form of two layers with a gap and the process is carried out at a temperature difference in the perpendicular direction along the gases the cross section at the entrance to the second layer is not more than 50 ° C. 2. A method according to claim 1, characterized in that the process is carried out at a catalyst heating temperature of 400-650 ° C