PROCESS FOR SYNTHESIS OF UREA AND A RELATED ARRANGEMENT FOR A REACTION SECTION OF A UREA PLANT

摘要

A process for synthesis of urea and a related reaction section of a urea plant, where: ammonia and carbon dioxide are reacted in a liquid phase in a first reaction zone (S1) and heat (Q1) is withdrawn from said first reaction zone to promote the formation of ammonium carbamate, the liquid product (103) from said first reaction zone is then passed to a second reaction zone (S2) distinguished from said first reaction zone, and heat (Q2) is added to said second reaction zone to promote the decomposition of ammonium carbamate into urea and water, where the liquid phase in at least one of said first reaction zone and second reaction zone is kept in a stirred condition. A downflow reactor for carrying out the above process is also disclosed.

主权项

1. A process for synthesis of urea from reaction of ammonia and carbon dioxide, the process comprising the steps of:
reacting ammonia and carbon dioxide in a liquid phase and in a first reaction zone (S1), and withdrawing heat (Q1) from said first reaction zone to promote the formation of ammonium carbamate, said first reaction zone producing a first liquid product mainly comprising ammonium carbamate, ammonia and water; and passing said first product to a second reaction zone distinguished from said first reaction zone, and adding heat to said second reaction zone to promote the decomposition of ammonium carbamate into urea and water, said second reaction zone producing a second liquid product containing urea, residual unconverted carbamate and excess ammonia, wherein the liquid phase in at least one of said first reaction zone and second reaction zone are kept in a stirred condition induced by mechanical stiffing means.