| 摘要 |
1,247,060. Improvements in the production of urea. STAMICARBON N.V. 18 Dec., 1968 [21 Dec., 1967], No. 60247/68. Heading C2C. In the preparation of urea, in which NH 3 produced from N 2 in an NH 3 -synthesis reactor is passed to a urea-synthesis reactor and therein reacted with CO 2 to form urea, an NH 3 -, N 2 - and H 2 -containing gas stream derived from the said ammonia-synthesis reactor is passed to an absorbing zone and therein passed in countercurrent flow with a solvent for NH 3 whereby NH 3 is removed from said gas stream in the form of an NH 3 solution, and the said NH 3 solution is passed to a desorbing zone and therein passed in countercurrent flow with one or more desorbing gases, which are inert to urea under the conditions prevailing in the ureasynthesis reactor, under conditions of temperature and gas flow whereby the arithmetical product of the molar fraction of NH 3 in the resulting NH 3 -containing gas multiplied by the pressure thereof is at least 100 atmospheres, and the said NH 3 -containing gas is passed to the said urea-synthesis zone. Suitable solvents for dissolving the gaseous NH 3 are water, aqueous solutions of salts in which NH 3 can be readily dissolved, e.g. ammonium nitrate, urea solutions and urea melts; suitable gases for use in the desorption step are air, carbon dioxide, nitrogen, hydrogen, or a mixture of carbon dioxide, nitrogen and hydrogen. The process may be operated continuously, suitable reaction schemes being described. |
