| 摘要 |
1,207,924. Urea. STAMICARBON N.V. 13 March, 1969 [16 March, 1968], No. 13347/69. Heading C2C. Urea is produced from ammonia and carbon dioxide in a combined urea-synthesis/ammoniasynthesis process in which (a) "synthesis gas" comprising hydrogen and carbon dioxide with carbon monoxide as contaminant and optionally also containing nitrogen is passed to an ammonium - carbamate - forming zone of a urea - synthesis zone, (b) oxygen is mixed with the synthesis gas in an amount based on the amount of carbon monoxide therein, (c) carbon monoxide in the effluent gas from the ammonium-carbamate - forming zone is oxidized to carbon dioxide, (d) carbon-dioxide is removed from the effluent gas with an ammoniacal solution to form an ammonium carbonate solution which is recycled to the ammonium - carbamate - forming zone, and (e) the effluent gas freed from carbon dioxide is passed to an ammoniasynthesis zone and the ammonia so produced is passed to the ammonium - carbamate - forming zone. The solution produced in the urea synthesis zone may be stripped to remove ammonium carbamate in two stripping stages at substantially equal elevated pressures, the stripping gas in the first stage being the above-mentioned synthesis gas and in the second stage being comprised of the gas streams used for the ammonia synthesis being substantially free from ammonia and carbon dioxide (see Specification 1,207,923. |
