FIELD: process engineering.
SUBSTANCE: invention relates to extraction of ammonia contained in gaseous purge flow produced in urea synthesis. Proposed method comprises the following stages: a) flushing of gaseous purge flow by aqueous acid solution at pH 1-6 to produce first cleaned gas flow and aqueous solution bearing ammonium salt. b) stripping of aqueous solution with ammonium salt fed from stage (a) after treatment by strong base representing an ionic hydroxide with high solubility in water at 50-250°C and 0.1-4 MPa to produce second gas flow including NH3, H2O and, possibly, CO2, and solution containing cation salt of said strong base; c) treatment of solution containing cation salt of strong base fed from stage (b) by membrane electrochemical process with formation of aqueous solution of acid used at stage (a), aqueous solution of base used at stage (b) and, possibly, diluted aqueous solution of cation salt of strong base. d) recycling said aqueous solutions of acid and base to stage (a) and stage (b) and recycling said second gas flow from stage (b) to urea synthesis process.
EFFECT: higher degree of ammonium extraction.
29 cl, 1 dwg, 1 ex
