Method for increasing capacity of existing urea process

Method for increasing capacity of existing urea process

CN
  • CN 1,078,205 C
  • Filed: 01/12/1998
  • Issued: 01/23/2002
  • Est. Priority Date: 01/13/1997
  • Status: Active Grant
First Claim
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1. improve the method for the throughput of existing urea process, existing urea process is included under the high pressure (P) ammonia and carbonic acid gas is added in the reactor (R), formed therein and comprised ammonium carbamate, ammonia, the reaction mixture of water and urea (M1), then, by once or several times reducing pressure and supplying with heat, in decompression part (SC), from reaction mixture, isolate gaseous ammonia and ammonium carbamate, the gaseous ammonia and the ammonium carbamate that are obtained liquid mixture (M2) and recovery by described reaction mixture are condensed, from separation of ammonia wherein (M3 '"'"') and obtain containing the ammonia soln (M3) of ammonium carbamate, utilize the solution (M3) obtain and ammonia (M3 '"'"') to prepare urea again, reclaim urea in urea recovery section (U) from mixture (M2), the feature of the method for the throughput of this raising existing urea process is:

  • (i) increase a stripping tower (S), wherein do not reduce pressure actually to the situation below the pressure (P) of reactor (R), the stripping ammonium carbamate from reaction mixture (M1) with carbonic acid gas or heat, obtain gaseous mixture (G1) and liquid mixture (M4), then liquid mixture (M4) is added in the decompression part (SC);

    (ii) increase a condenser (C), to wherein adding gaseous mixture (G1), ammonia and optional carbonic acid gas, wherein do not reduce pressure actually to the situation below the pressure (P) of reactor (R), gaseous mixture (G1) is condensed, formation contains the liquid mixture (M5) of urea, water and ammonium carbamate, wherein urea content be at least under condensing condition available urea equal amount 30%, and gaseous mixture (G2), the bottom of liquid mixture (M5) Returning reactor (R);

    With(iii) increase a washer (SCR), wherein gaseous mixture (G2) contacts with the ammonia soln that contains ammonium carbamate (M3), form liquid mixture (M6) and washed gaseous mixture (G3), then liquid mixture (M6) is added in the condenser (C).

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