Patent ID: 9447032
Filing Date: 2016-09-20
CPC Classification: C07C

Claim Text:
1. A process for producing urea by converting ammonia and carbon dioxide to urea wherein an aqueous urea solution containing non converted ammonia and carbon dioxide, leaving a urea reaction zone is fed to a stripper, wherein in said stripper part of the non-converted ammonia and carbon dioxide is separated from the aqueous urea solution, which urea solution leaves the stripper to a first recovery section of one or more serial recovery sections and is subsequently fed to one or more urea concentration sections, wherein the urea solution leaving the stripper is subjected to an adiabatic expansion, thus creating a vapor and a liquid, which are separated before the liquid enters a first recovery section and the vapor is condensed, and wherein the heat released from the condensation of the vapor resulting from said expansion is used for heating downstream in the process, wherein the first recovery section is operated at a pressure of 0.1-1 MPa; and/or wherein the pressure of the vapor after the adiabatic expansion is at least 0.2 MPa higher than the pressure in the first recovery system.