FIELD: process engineering.
SUBSTANCE: invention relates to production of urea solutions suitable for selective catalytic reduction of nitrogen oxides, namely, for their removal. Water flow containing urea produced at extraction section is subjected to evaporation to separate steam flow bearing water and ammonia and, hence, to produce concentrated solution not containing, in fact, said ammonia. Said solution is diluted to obtain solution with urea concentration suitable for use in selective catalytic reduction. Propose plant comprises synthesis section for conversion of ammonia and carbon dioxide into first water flow containing urea, ammonia urethane and unreacted free ammonia, extraction section to dissociate urethane and circulate ammonia and carbon dioxide to synthesis section so that second water flow containing urea, water and residual ammonia are produced. Said plant comprises extra section to convert a portion of second flow into solution with low urea concentration. Note here that said second section includes evaporator and mixer.
EFFECT: efficient production.
12 cl, 3 dwg, 1 ex
