An Integrated Process for Ammonia-Urea Manufacture

After introducing the concept of combining ammonia manufacture and its subsequent conversion into urea within the battery limits of a single process plant, the authors describe the integrated process now developed to industrial scale by Snamprogetti. Based on the Snamprogetti total recycle ammonia stripping process, this new process has, as its essential features:

– the separation of ammonia from recycle syngas in the ammonia synthesis loop by absorption in water,

– the removal of carbon dioxide from the raw ammonia syngas by absorption in ammonia solution to produce carbamate for direct conversion to urea.

Both these key steps are performed in falling film heat exchangers. This equipment is described, together with details of other development work carried out on novel aspects such as synthesis gas drying, high pressure methanation, etc. Finally the authors consider the industrial application of their process in circumstances of using heavier feedstocks than natural gas, and of providing part of the production as ammonia.

Dott. Ing. V Lagana and Dott. Ing. U Zardi, Snamprogetti S.p.a., Italy

28 pages, 9 figures, 4 tables. 5 references.