Changing of N2O concentration in the gas passage of UKL-7 unit in the non-concentrated nitric acid production

In order to neutralize the waste gases of non-concentrated nitric acid production from nitrogen oxides the N2O concentration monitoring in the nitrous and outlet gas was hold in the tract of nine units UKL-7 for JSC «NAC “Nitrogen”», using high-temperature catalytic treatment (seven units) and low-temperature selective catalytic purification (two units). Formation of N2O in the platinoid catalyst bed occurs on the first grid in the gas pipe due to the relatively low temperatures. Samples were taken at 6 analysis points. Due to the lack of analysis point at the exit from the catalyst bed, the missing values of N2O concentration are determined by calculations based on data obtained in the experimental reactor with a working diameter 0.15 m, functioning in the mode of industrial unit UKL-7 reactor. Monitoring results showed that the concentrations of N2O between individual units are significantly different (in particular, the N2O concentrations in nitrous gas after the boiler are in the range 1320–1810 ppm), which can be explained by differences in the hydrodynamic flow of the gas flow through the catalyst bed. In units with high-temperature catalytic purification of tail gas the N2O concentration in significantly below the allowable values, so the additional removal of N2O is not required. In the tail gases low-temperature selective catalytic purified the increased concentration of N2O (680–1130 ppm) was found, necessitating further purification, with the tail gas cleanup unit from N2O advisable to place after the gas turbine.

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