SU1544469A1 - Method of cleaning tail gases from nitrogen oxides - Google Patents

Abstract

The invention relates to processes for the purification of tail gases from nitrogen oxides and can be used in the production of nitric acid and the processes of nitrate processing of natural raw materials. The aim of the invention is to increase the service life of the catalyst and simplify the instrumentation of the process. To achieve this goal, in the method of cleaning tail gases from nitrogen oxides, including the supply of methane and air into the combustion chamber, burning methane in air, heating tail gases to 330-350 ° C by mixing them with the products of combustion of methane and catalytic reduction of nitrogen oxides to alumina - palladium catalyst; additional methane is introduced into the combustion chamber to ensure that the methane-oxygen ratio of air is 0.71-1.00. With the implementation of the method, a sufficiently high degree of purification of tail gases from nitrogen oxides is achieved, the instrumentation of the process is simplified and the service life of the catalyst is increased, the running time of which is 1.5–3.0 times longer than the normalized one.

Description

The invention relates to processes for cleaning tail gas from nitrogen oxides and can be used in the production of nitric acid and the processes of nitrate processing of natural raw materials.

The purpose of the invention is to increase the service life of the catalyst and simplify the instrumentation of the process.

Example 1. Tail nitrosis-1 gas in an amount of 33,000 Nm3 / h, containing 0.131 nitrogen oxides and 2.1% of oxygen, enters the combustion chamber of the reactor, into which, 1130 nme / h of methane and 6850 nm3 / h are fed to the reel air, providing the ratio of methane to air oxygen supplied to the burner is 0.785. The resulting combustion products, -, containing methane, when contacted with the tail nitrous gas, are heated to 75 ° C, after which catalytic reduction of nitrogen oxides is carried out on an aluminum-palladium catalyst, the running time of which is 20,000 hours. In a purified gas the content of nitrogen oxides is 0.001%, hydrogen 0.08%, carbon monoxide 0 ,.

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Example 2. 33200 Nm3 / h of tail gas nitrous, containing 0.15% of nitrogen oxides, 2.7% of oxygen, enters the combustion chamber of the reactor, into which 1210 nm3 / h of methane and nm3 / h of air are supplied to the burner. , ensuring the ratio of methane - oxygen of the air supplied to the burner is equal to 0.895. The resulting combustion products containing methane, when contacted with tail nitrous gas, heat the latter, after which catalytic reduction of nitrogen oxides is carried out on an aluminum palladium catalyst, the run time of which is 22000 hours. In a purified gas, nitrogen oxides are absent, the content hydrogen is 0.05%, carbon monoxide 0.06%.

Example 3. Tail nitrous gas in the amount of 52,000 im3 / h, containing 0, nitrogen oxides and 1.4% of oxygen, goes on mixing with flue gases produced during the combustion of 1380 nm3 / h of methane and 9200 nm3 / h of air methane - the oxygen of the air supplied to the burner is 0.715). A mixture of methane-containing flue gas and tail nitrous gases, having a temperature of 90 ° C, is fed to a catalytic reduction of nitrogen oxides on an aluminum-palladium catalyst that has worked out 0000 h (rerun 26000 h). The purified gas contains 0, nitrogen oxides, 0.01% hydrogen and 0.05% carbon monoxide.

Example k. Flue gases produced by burning 1380 nm / h of methane to 9300 Nm3 / h of air (the ratio of methane to air oxygen supplied to the burner of the combustion chamber is 0.71) is mixed with the tail nitrous gas, in the amount of HOOO nm3 / h with content of 0.15% nitrogen oxides and 1.5% oxygen. The resulting mixture is then directed to catalytic reduction of nitrogen oxides on the alumina palladium catalyst. The purified gas contains 0.006% 5 nitrogen oxides, 0, OD% carbon monoxide and 0.1% methane.

When implementing the proposed method, the instrumentation of the process is simplified and the service life of the catalyst is increased (the running time

which is 1,, 0 times the normalized one).

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Claims (1)

Invention Formula 5 A method of cleaning tail gases from nitrogen oxides, including the supply of methane and air into the combustion chamber, burning methane in air, heating tail gases to 390-550 ° С by 0 mixing them with the combustion products of methane in the air and the catalytic reduction of nitrogen oxides on the alumina palladium catalyst, characterized in that 35 in order to increase the service life of the catalyst and simplify the instrumentation of the process, an additional amount of methane is introduced into the combustion chamber to ensure the ratio to methane-oxygen of air 0.71-1.00.