Monitoring of platiniod losses during ammonia oxidation in industrial UKL-7 units

Abstract

Platinoid losses were monitored during oxidation of ammonia in industrial UKL-7 type units bearing one- and two-step catalytic systems. Twelve units at the Acron Co. and eleven units at the Nevinnomysskiy Azot Co. were inspected. Approximately equal platinoid losses along the gas flow were observed from the first five woven gauzes in the 1,70 m diameter reactors and from the first three gauzes in the 1,93 m diameter reactors, while the losses from the following gauzes decreased considerably. The concepts of mechanochemical losses (MCL) and reduced mechanochemical losses (related to the amount of produced nitric acid) were introduced as dependent on the intensity of the catalytic reaction and on the specific gasdynamic conditions in the catalytic reactor. It was established that the reactor diameter and arrangement of the gauzes in the reactor determine the ratio of platinoid weight losses from the catalyst woven gauzes; the data obtained were used for estimation of the previously unknown thermal losses. The demonstrated linear dependence of the specific losses of platinoids on reduced MCL allows MCL to be calculated for any UKL-7 unit. Experimental dependences of the ammonia conversion over the platinoid gauze on the gauze arrangement in the catalyst cartridge were determined to indicate the necessity of correcting the applied mathematical model. Analysis of MCL makes it possible to reveal regularities of operational damage of platinoid woven gauzes in various reactors and to predict the degree and type of the catalyst destruction in catalytic reactors bearing new effective catalytic systems.