METHOD AND UNIT FOR SYNTHESIS OF NITRIC ACID, METHOD FOR IMPROVEMENT Russian patent published in 2021 - IPC C01B21/26 C01B21/28 C01B21/46 B01D53/02 B01D53/56 

FIELD: chemistry.

SUBSTANCE: invention relates to the area of industrial production of nitric acid. A double-pressure unit for synthesis of nitric acid comprises: a reactor (4) wherein an off-gas stream (15) containing nitrogen oxides is formed; an absorption column (6) wherein nitrogen oxides react with water producing crude nitric acid; a compressor (5) increasing the pressure of the off-gas stream (15) of the reactor to the absorption pressure. The absorption tower (6) operates at a pressure exceeding the pressure in the reactor. The unit also comprises a first scrubber (37) and a second scrubber (7). The first scrubber (37) desorbs nitrogen oxides from the outlet stream (27) of the absorption column (6) product by air (39) producing a partially purified nitric acid stream (40) and a stream of air (41) saturated with nitrogen oxides, wherein the first stream is supplied to the second scrubber (7) and the second stream is returned to the discharge side of the compressor (5).

EFFECT: increased productivity of the unit and synthesis of nitric acid of higher purity are ensured.

15 cl, 2 dwg