| 摘要 |
<p>PURPOSE:To prepare the economically, by heating the urea synthesis liquid obtained by the reaction of NH3 and CO2 to decompose the unconverted material into NH3 and CO2, and recycling the unconverted material to the urea synthesis stage using the transfer of heat in the system and without using external energy. CONSTITUTION:The urea synthesis liquid (composed of urea, water, unconverted ammonium carbamate, etc.) is supplied from the urea synthesis tube 1 through the pipe 11 to the high pressure decomposition reactor 2 maintained to the pressure equal to that of urea synthesis. The liquid is heated in the decomposition reactor 2 at 170-220 deg.C to decompose at least a part of the unconverted material to the gaseous mixture of NH3 and CO2, which is transferred through the pipe 16 to the condenser 3 to cool and separate the gas. The separated gas is recycled to the synthesis tube 1 through the pipe 20. The mixed gas is condensed and absorbed at the ejector part of the condenser 3 using a cooling medium as the driving medium. The pressure of the aqueous solution of urea is released by the reducing valve 14, and the solution is sent to the low-pressure decomposition stage and the finishing stage through the pipe 15 to obtain the urea product.</p> |
