FIELD: chemistry.
SUBSTANCE: invention relates to a method of producing an aqueous solution containing urea, meant for use when removing nitrogen oxides from gaseous combustion products and flue gases. The method involves steps for: using carbon dioxide to wash at least a portion of concentrated aqueous urea solution obtained directly from or downstream the urea extraction section of an apparatus for producing urea and containing residual free ammonia, to obtain a first vapour phase containing carbon dioxide and possibly ammonia and concentrated aqueous urea solution containing carbamate and essentially not containing free ammonia, and dilution of said concentrated aqueous urea solution containing carbamate and essentially not containing free ammonia with water until the required urea concentration in the aqueous solution is achieved. Also disclosed is an apparatus for producing an aqueous solution containing urea (versions) and a method of modernising existing apparatus for producing urea (versions).
EFFECT: invention significantly reduces power consumption.
21 c, 2 dwg
