| 摘要 |
<p>1,160,030. Synthesis of urea. STAMICARBON N.V. 19 April, 1967 [22 April, 1966], No. 18051/67. Heading C2C. Urea is obtained by reacting NH 3 and CO 2 under elevated temperature and pressure to form an ammonium carbamate melt which is subsequently transferred to a urea formation zone and transformed therein into a urea solution which contains ammonium carbamate and/or dissolved NH 3 and CO 2 , stripping the said urea solution with VH 3 and/or CO 2 and recycling the stripped NH 3 and CO 2 to the ammonium carbamate formation-zone or to the urea formation-zone, after which the resulting urea solution is optionally expanded to effect further removal of dissolved NH 3 and CO 2 which are thereafter absorbed in water and the solution so obtained is recycled to the carbamate or urea formation zone, and the urea solution freed of dissolved NH 3 and CO 2 is removed for further processing, wherein in the said process the feed of one or both of the reaction components NH 3 and CO 2 to the carbamate formation zone is controlled so that the NH 3 : CO 2 molar ratio of the NH3 and CO 2 present in the liquid phase as such or as NH 3 and CO 2 bonded otherwise than in the form of urea or biuret, is maintained at a value of from 2:1 to 3:1, and the said ratio in the urea formation zone is maintained at a value of from 3:1 to 6:1. The said molar NH 3 : CO 2 ratios in the liquid phases may be adjusted by controlling the molar NH 3 : CO 2 ratio in one or both of the gas phase(s) that are in contact with the liquid phase(s) such that the said gas phase molar ratio is maintained within the range 1:1 to 6:1. A suitable form of apparatus for carrying out the process is described.</p> |
