| 摘要 |
<p>An improved process for manufacturing melamine from urea simplifies the recovery of melamine, carbamate and ammonia from a fluidized bed reactor effluent stream by operating the process at a pressure between 1.4 and 2 MPa. In such a manner, a carbamate solution can be produced at a sufficiently high concentration for use in a urea plant without an intervening concentration step. In addition, ammonia recycled as a fluidizing gas can be condensed against cooling water to permit easy separation of noncondensables such as oxygen which is used in the process as a passivator for carbamate corrosion inhibition. The melamine product is produced as an aqueous solution free of melamine solids. Heat is recovered from the carbamate condensation and used for the vaporization of ammonia which is recycled to the reactor for fluidization.</p> |
