GB336638A - Improvements in process for the manufacture of concentrated nitric acid - Google Patents

Abstract

336,638. Triggs, W. W., (Du Pont de Nemours & Co., E. I.). April 17, 1929. Nitric acid.-In producing nitric acid from gases containing nitrogen oxides such as are produced by the are process or by the catalytic oxidation of ammonia, by a series of successive oxidations and absorptions in water or nitric acid, the process is carried out under pressures of 50-150 lb. per sq. in. in a tower 20 comprising from ten to twenty sections 22 each formed with a base plate 23 having an upstanding wall 24, an overflow cup 25 for carrying liquid through pipe 26 into the next lower section, and a cap 27 provided with openings 29 at or near its base for the passage of the gases. In carrying out the process, a mixture of air and and ammonia under pressure may be oxidized in a converter 9, condensation of the reaction mixture be effected in a condenser 12, the condensed liquid being passed say to the middle of the tower by pipes 13, 19, the nitrous gases be oxidized in a chamber 15, and be passed to the box of the tower through pipe 17. Water may be supplied to the top of the tower through a pipe 36 and the concentrated nitric acid be withdrawn from the base of the tower through a, pipe 32. The gases are alternately scrubbed with liquid in each section and further oxidized on their passage to the next higher section. The tower may be constructed of chromium steel. Specification 336,233 is referred to.