Process for the preparation of urea

1. Process for the preparation of urea from ammonia and carbon dioxide in a urea plant that contains a high-pressure synthesis section and one or more recovery section(s) at a lower pressure, the high-pressure synthesis section comprising a reactor, a stripper and a condenser, characterized in that gases leaving the high-pressure synthesis section are condensed in a medium- pressure condenser at 0.5 -12 MPa to which also a carbamate stream from one of the recovery sections is supplied, after which at least a part of the formed condensate is supplied to the high-pressure condenser.

2. Process according to claim 1 , characterized in that the formed condensate is also partly returned to the high-pressure reactor.

3. Process according to claim 1 , characterized in that the formed condensate is supplied in its entirety to the high-pressure condenser.

4. Process according to claim 1 , in which the high-pressure synthesis section also comprises a scrubber, characterized in that gases leaving the high-pressure synthesis section are condensed in a medium-pressure condenser to which also a carbamate stream from one of the recovery sections is supplied, after which at least a part of the formed condensate is supplied to the high-pressure scrubber and from there to the high-pressure condenser.

5. Process according to claim 4 , characterized in that the formed condensate is also partly returned to the high-pressure condenser and/or the high-pressure reactor.

6. Process according to claim 4 , characterized in that the formed condensate is supplied in its entirety to the high-pressure scrubber.

7. Process according to claim 1 , characterized in that the temperature in the medium-pressure condenser is between 70 and 140° C.

8. Process according to claim 1 , characterized in that the carbamate supplied to the medium-pressure condenser comes from the low-pressure recovery section of a urea plant.

9. Process according to claim 4 , characterized in that the urea plant comprises a high-pressure synthesis section and a low-pressure recovery section.

10. Process according to claim 1 , characterized in that the gas stream leaving the medium-pressure condenser is condensed in a medium-pressure scrubber at a pressure of 0.5-12 MPa to which a carbamate stream from one of the recovery section(s) of a urea plant is supplied, after which at least a part of the formed condensate is supplied to the medium-pressure condenser.

11. Urea plant containing a high-pressure synthesis section and one or more recovery section(s), the high-pressure synthesis section comprising a reactor, a stripper and a condenser, characterized in that the urea plant contains a medium-pressure condenser, which is connected to a gas outlet of the high-pressure synthesis section.

12. Urea plant according to claim 11 , in which the high-pressure synthesis section also comprises a scrubber, characterized in that the medium-pressure condenser is connected to the gas outlet of the high-pressure scrubber.

13. Urea plant according to claim 11 , characterized in that the urea plant also contains a medium-pressure scrubber, which is connected to the gas outlet of the medium-pressure condenser.

14. Process for optimization of a urea plant that contains a high-pressure synthesis section and one or more recovery section(s), the high-pressure synthesis section comprising a reactor, a stripper, a condenser and optionally a scrubber, characterized in that a medium-pressure condenser is added to the urea plant in which gases coming from the high-pressure synthesis section are condensed, and the capacity of the high-pressure stripper is increased.

15. Process according to claim 14 , characterized in that the capacity of the high- pressure stripper is increased by additionally installing an extra stripper.

16. Process according to claim 14 , characterized in that also a medium- pressure scrubber is additionally installed, in which the gases from the medium-pressure condenser are absorbed.