SU1701356A1 - Nitric acid production exhaust gas cleaning plant - Google Patents

Abstract

The present invention relates to waste gas treatment plants in the manufacture of HMHOs, which allow decreasing the residual concentration of NOx, CO and CHzO in the purified gases. The installation includes a combustion chamber, a catalytic reactor filled with a two-layer aluminum-palladium catalyst, a turbine with a combustion chamber, a waste heat boiler, an additional catalytic reactor filled with a ruthenium-palladium catalyst on an Al220z support, and an exhaust pipe connected in series with pipelines. The installation provides a residual concentration of NOx, CO and CH20 equal to 36-46, 41-50 and 0.0025- 0.0095 mg / m3, respectively. 1 il.

Description

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The invention relates to waste gas treatment plants in the production of nitric acid and can be applied in the chemical and energy industries.

The purpose of the invention is to reduce the residual concentration of nitrogen oxides, carbon monoxide and formaldehyde in purified gases.

The drawing shows a diagram of an installation for cleaning waste gases in the production of nitric acid.

The installation includes a combustion chamber 1 connected in series with pipelines, located at the inlet of a catalytic purification reactor 2 filled with a two-layer catalyst 3, a combustion chamber 4, turbines 5, a waste heat boiler 6, a reactor 7 filled with ruthenium-palladium catalyst 8 on alumina and an exhaust one pipe 9.

The operation of the installation is carried out as follows.

PRI me R 1. Tail gases in the amount of 67,000 Nm3 / h after absorption columns with a nitrogen oxide content of n / b 0.15% by volume and a temperature of 30 ° C enter the combustion chamber 1 of reactor 2, where they are heated to a temperature of 500 ° C by mixing them with hot flue gases produced by burning natural gas with air. The excess oxygen ratio at the inlet to the combustion chamber of the reactor is 0.9-0.95.

After the combustion chamber, tail gases mixed with natural gas (pg) according to XI

ABOUT

WITH

ate

Os

wearing CH4: 02 0.52-0.55 is sent to the catalytic purification reactor.

The amount of natural gas fed to the reactor 2 is 700 m3 / h.

In the reactor on a two-layer catalyst 3, where the top layer is aluminum-palladium (APK-2) catalyst on a carrier, containing 2% Pd, in the amount of 2.7 tons, and the bottom one is spent APC-2, containing 1.7% Pd, in the amount of 2 , 7 tons, at a temperature of 690-730 ° C, hydrogen-containing components are burning and

reduction of nitrogen oxides to elemental nitrogen.

The content of nitrogen oxides after reactor 2 is 67.9 mg / m3, carbon monoxide 1206 mg / m, methane 130 mg / m, formaldehyde 3.7 mg / m.

The purified tail gases after the catalytic cleaning reactor are mixed with the flue gases of the combustion chamber 4 with a temperature not higher than 700 ° C, are fed into the gas turbine 5.

The gases exhausted in the turbine 5 with a temperature not higher than 410 ° C are directed to a waste heat boiler 6, in which the tail gases are cooled to a temperature not higher than 185 ° C.

The purified cooled tail gas after the recovery boiler 6 is sent to the reactor 7 loaded with ruthenium-palladium catalyst 8 containing 0.15% Pd and 0.15% Ru on an alumina carrier in an amount of 3.5 tons at a height of a layer of-500 mm. In the reactor 7 at a temperature of 230-240 ° C, a pressure of 0.06 MPa and a space velocity of 12000, carbon monoxide is burned to a content not higher than 50 mg / m3, decomposition of nitrogen oxides to 40 mg / m3 and formaldehyde to 0.0025 mg / m .

PRI mme R 2. The method is carried out analogously to example 1.

The composition of the gas at the outlet of the reactor 20 mg / m:

NOX40,7

CO1270

SNd100

CH204,6

The composition of the gas at the entrance to the reactor 7, mg / m:

NOX117.5

CO769 CH470

CH201.3

The composition of the gas at the outlet of the reactor 7, mg / m3:

MOh46.1

SO43

CH470

CH200,0095

PRI me R 3. The method is carried out analogously to example 1.

The composition of the gas at the outlet of the reactor 2, mg / m3:

NOX36,2

CO1412

CH4120

CH201.2

The composition of the gas at the entrance to the reactor 7, mg / m3:

NOX103,1

CO680

CH480

CH202,6

The composition of the gas at the outlet of the reactor 7,

mg / m3:

NOX WITH

CH4

CH20

41.5

41

80

0.0025

Purification of the gas at the facility of this invention reduces the residual concentration in the purified gases to 36-46 mg / m3 for NOX, 41-50 mg / m3 for CO and

0.0025-0.0095 mg / m3 for CH20 versus 103 mg / m3 for NOx, 12500-25000 mg / m3 for CO and 1.2-4.6 mg / m for CH20 in a known installation. Consumption of natural gas fed to the first reactor is reduced by 5-8 nm / t

HN03.

Claims (1)

Claims An installation for purifying waste gases in the production of nitric acid, comprising a combustion chamber connected in series, a catalytic reactor filled with a two-layer aluminum-palladium catalyst, a turbine with a combustion chamber, a waste heat boiler and An exhaust pipe, characterized in that, in order to reduce the residual concentration of nitrogen oxides, carbon monoxide and formaldehyde in the purified gases, it additionally contains a reactor downstream of the recovery boiler and filled with alumina-palladium catalyst. oo t Have Oq CD