PURPOSE: To obtain the titled compound in high yield, by using the urea synthetic solution for urea from ammonia and carbon dioxide partially as an absorption medium for the unreacted ammonia and carbon dioxide.
CONSTITUTION: NH3 is reacted with CO2 in a urea synthesizing tube 1, and the urea synthesizing solution containing the resultant urea, unreacted NH3, unreacted CO2 and water is stripped in a stripper 2 by the stripping action of CO2 from a tube 24 as a separation step in at least one state, and a mixed gas of the unreacted NH3 with the unreacted CO2 is separated. The resultant separated gaseous mixture is at least partially absorbed in an absorption medium and recirculated through the urea synthesizing tube 1. In the method, the urea synthetizing solution is partially sucked from the top of the urea synthesizing tube 1 through a tube 31 without subjecting to the separation step, introduced into a carbamate condenser 3 and used as the absorption medium to absorb the above-mentioned mixed gas of the NH3 with CO2 from a tube 25.
INOUE SHIGERU
MORIKAWA HARUYUKI
YAMAMOTO YOSHIO
TOYO ENGINEERING CORP