Urea → Ammonia

Participants

Reaction Steps

In another embodiment, the present invention provides apparatus for manufacturing melamine from urea. A reactor is provided for converting urea and a fluidizing amount of ammonia in the presence of a catalyst at a pressure from about 1.4 MPa to about 2 MPa and an effective temperature into melamine and forming a reactor effluent stream comprising melamine, ammonia, carbon dioxide and water. A quench zone is provided for mixing the effluent stream with an aqueous quench stream to form a vapor-liquid mixture essentially free of solids. A separation zone is provided for separating the vapor-liquid mixture into a concentrated aqueous melamine product stream essentially free of solids, ammonia and carbon dioxide, and a high pressure vapor stream essentially free of urea and melamine. An absorption zone is provided for contacting the high pressure vapor stream with aqueous ammonia and refluxing the high pressure vapor stream with liquid ammonia to form a concentrated aqueous ammonium carbamate stream and an overhead ammonia vapor stream essentially free of carbon dioxide and water vapor. A condenser is provided for condensing the overhead ammonia vapor from the absorption zone to form a liquid ammonia stream. A heat exchanger is provided for vaporizing the liquid ammonia stream to form a fluidizing ammonia stream. A line is provided for supplying the fluidizing ammonia stream to the reactor.

Provenance & Evidence