DEVICE FOR TRAPPING PLATINOIDS IN CATALYTIC OXIDATION OF AMMONIA Russian patent published in 1998 - IPC

FIELD: equipment for production of nitric acid, in particular, wire screens for trapping of platinoids in catalytic oxidation of ammonia. SUBSTANCE: device includes trapping screens netted from wire with diameter of 0.06-0.12 mm and having 225-1024 mesh/sq.cm. The first screens in direction of gas flow are screens with low mesh density and arranged in packages containing 2-4 pieces with turning of wire direction in adjacent screens through angle of 45 deg. Packages are located between separating screens netted from wire with diameter of 0.12-0.4 mm and density of 49-225 mesh/sq. cm. Trapping screens are made of palladium-base alloy with addition of 9% of platinum, 0.5% of tungsten or 5% of nickel, 0.2% or 0.5% of tungsten, 0.1% of yttrium or 5% of platinum, 5% of copper, 0.1% of yttrium. Besides, the first trapping screens in direction of gas flow may be made of wire with larger diameter or from wire of the same diameter. The last trapping screen in direction of gas flow is a screen of high density, or a package of two trapping screens of different density. Trapping screens may be made of the same or different alloys. As compared with the devices of the analog application, the proposed device provides for considerable increase of platinum trapping degree, and service lief, reduced consumption of precious metals. In addition, the claimed screen package ensures additional stage of ammoniaoxidation and as a result, reduction of number of installed catalytic screens. EFFECT: higher efficiency. 5 cl, 1 tbl