FIELD: chemistry.
SUBSTANCE: invention relates to an improved method for synthesis of urea from ammonia and carbon dioxide at high pressure and temperature with formation of ammonium carbamate as an intermediate product. The method includes a high pressure synthesis section comprising at least one step for separating unreacted ammonium carbamate from ammonia via stripping decomposition, carried out in a vertical apparatus which is a stripping column. Said step also involves feeding a CO2 stream, heated to temperature 130-230°C, into the bottom part of said stripping column, in amount of 1-15 wt % with respect to total weight of fresh CO2, containing a passivating agent, fed into the process. The amount of this agent is such that its equivalent O2 content in moles ranges from 0.05 to 0.8% with respect to the number of moles of CO2 in said stream. Fresh CO2 is compressed in a multiple-stage compressor having intermediate heat-exchange stages. Apparatus for realising the improved urea synthesis method is also provided. The invention enables to optimise the urea synthesis process.
EFFECT: invention enables to optimise the urea synthesis process.
21 cl, 3 dwg, 3 ex
