GB173060A - Processes of making sulphuric acid - Google Patents

Abstract

173,060. Reed, C. J. Sept. 20, 1920. Sulphuric acid; nitro-sulphonic acid. - A gaseous mixture of sulphur dioxide, nitric oxide, or other higher oxide of nitrogen, and air or oxygen is heated, for example, to 200-400‹ C. and the resulting compounds produced by the union of sulphur trioxide with the nitrogen oxides are absorbed in concentrated sulphuric acid. Sulphuric acid is liberated and nitrogen oxides recovered for re-use by treating this solution, preferably on a separate apparatus with water equivalent to the sulphur dioxide used. Sulphur dioxide and air pass through the pre-heater N to the reaction chamber A, heated by the gases from the furnace Q. The addition compounds of the nitrogen oxides and sulphur trioxide are absorbed in the packed tower F fed with concentrated sulphuric acid, and the solution passes through the liquid seal L to the vessel I maintained at a temperature a little below the boiling- point of sulphuric acid, and in which the solution is decomposed. The necessary amount of water is supplied from the vessel E and the escaping nitrogen oxides pass into the reaction chamber through the pipe D. Sulphuric acid is withdrawn at K, and the removal of nitrogen oxides is facilitated by allowing air to enter through the cock R. Alternatively the solution of the compound of sulphur trioxide and nitrogen oxides in sulphuric acid may be solidified by cooling, e. moved from the system, and treated as above described. Also, air or oxygen, sulphur dioxide, and a higher oxide of nitrogen may be brought together in the presence of sulphuric acid at the necessary temperature and the resulting solution decomposed as before.