| 摘要 |
industrial inorganic synthesis. SUBSTANCE: urea is prepared from ammonia and carbon dioxide, which are fed into reaction stage comprising two clearly differing reaction zones functioning largely at the same pressure between 130 and 180 kg/sq.cm but at operation temperatures mainly differing by 5 to 60 C. Reaction products in subsequent separation stages are separated from unconverted reactants. Separated gas flow comes out of the first reaction zone operated at high temperature and enters the second zone operated at lower temperature. Liquid stream containing ammonia and/or ammonium carbonate passes from the second zone into the first one, said gas flow preferably representing at least 5 wt % of the liquid stream coming out of the first zone and directed into following separation stages. Ratio of urea to the sum of urea and carbamate in stream leaving reaction stage is maintained above 70%. There is also condenser disposed preferably before the second reactor in gas mixture-supply line. As the second reactor, dephlegmating heat exchanger can be used preferably disposed on the top of the first reactor and provided with a set of plates to communicate with the first reactor. Method can also be used to improve current urea production process. EFFECT: increased (by 70-85%) conversion of carbon dioxide at the same pressure. 34 cl, 4 dwg, 4 ex
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