Total Recycle Processes
In Total Recycle processes the urea synthesis occurs at high pressure and is then followed by medium- and low-pressure sections where the unreacted carbamate is decomposed and the resulting carbon dioxide and ammonia are recovered. Compared with modern CO2 or ammonia stripping processes they lack a high-pressure decomposition and condensation stage. Ammonia and carbon dioxide are recycled separately in the form of pure liquid ammonia and aqueous carbamate solution. Total recycle processes are typically operated with high N/C molar ratios (3.8-4.5) in the synthesis reactor to maximize carbon dioxide conversion.