Absorption column comprising a feed box having a serrated weir and a structured packing and process for the production of nitric acid

A vertical absorption column for absorption of nitrogen oxides from a process gas comprising said nitrogen oxides into water for production of an aqueous nitric acid solution, comprising:

• a structured packing;
• a liquid distributor, located directly above the structured packing, comprising perforated trays and a feed box having a serrated weir for distribution of a liquid through upward-pointing serrations of the serrated weir into the perforated trays;
• a plate packing comprising a plurality of horizontal plates, provided with cooling means;
• an inlet for an addition of oxygen to a lower part of the vertical absorption column;
• an inlet for the process gas comprising nitrogen oxides from an ammonia oxidation process at the lower part of the vertical absorption column;
• an inlet for an aqueous solution at an upper part of the vertical absorption column;
• at least one nitric acid outlet at a bottom of the vertical absorption column;
• and
• an outlet for tail gas comprising nitrogen oxides at a top of the vertical absorption column,
• wherein the liquid distributor and the structured packing are arranged between a lowermost horizontal plate of the plate packing and the inlet of process gas containing nitrogen oxides, and the aqueous solution is an aqueous solution of nitric acid.