UREA PRODUCTION PLANT AND METHOD OF IMPROVEMENT THEREOF Russian patent published in 1999 - IPC

FIELD: production of inorganic compounds. SUBSTANCE: plant for production of urea from ammonia and carbon dioxide includes first and second urea- synthesis reactors, reaction mixture separation section including section wherein free ammonia and carbamate are separated from aqueous solution of urea contained in the first and second reactor products. The second reactor is of "single cycle" type with higher productivity than that of the first reactor, to which the second reactor is connected in parallel. In the first reactor, pressure about 150 bar and temperature about 190 C are maintained, whereas the first one ensures 240 bar and 195 C. Primary section of the second reactor comprises "boiler-type" reactor which allows partial removal of reaction heat. Distinguishing feature of invention consists in that the first reactor communicates over liquid line with ammonia evaporation section serving for separation of free ammonia and carbamate in flow of products withdrawn from reactor. Total productivity of plant is distributed such that productivity of the first reactor varies from 50 to 95% of the total productivity. EFFECT: enhanced process efficiency. 12 cl, 3 dwg