METHOD FOR ABRUPT COOLING OF EXHAUST GAS OF MELAMINE SYNTHESIS Russian patent published in 2024 - IPC C07D251/60 

FIELD: chemistry.

SUBSTANCE: invention relates to a method for synthesis of melamine from urea. According to the proposed method, the exhaust gas containing ammonia, carbon dioxide and melamine formed during the melamine synthesis is abruptly cooled to extract the melamine contained therein. Abrupt cooling of exhaust gas (2) includes: bringing into contact in countercurrent of upward flow of exhaust gas with downward flow of liquid ammonia (3) in first part (10) of quenching apparatus (1), which results in precipitation of solid melamine and formation of washed off gas (6) with low content of melamine or substantially without melamine, discharged from the first part of the apparatus; Then, the precipitated solid melamine is brought into contact with liquid solvent (4) in second part (11) of the apparatus, located below the first part, thus forming a melamine solution or a melamine suspension discharged from the apparatus. Invention also relates to an apparatus for producing melamine using said method.

EFFECT: disclosed method enables to obtain washed exhaust gas with low content of melamine or substantially free of melamine and melamine solution or suspension, which are mainly free from dissolved ammonium carbonate or carbamate.

22 cl, 1 dwg, 2 ex