Japanese Patent JPH0462309

B2

PURPOSE:In the process for urea synthesis, the temperature in the cooler for absorption of unreacting gas mixture is controlled by using the cooling water of elevated temperature to dry crystalline urea, and feeding cold water and removing hot water, so that the amount of hot water is kept in a certain range in the tank. CONSTITUTION:In the process for urea synthesis from ammonia and carbon dioxide, hot water is fed from storage tank 3 into line 12 so that the flow rate of the water passing through the cooler 1 is maintained at 0.25-4m/sec. The heat in the hot water whose temperature is raised by heat absorption from the unreacting ammonia and carbon dioxide mixed gas which has been separated from the urea synthesis solution is utilized to preheat the air for drying crystalline urea from aqueous urea solution. The temperature-decreased water is circulated to the storage tank 3, while low-temperature water is fed from the line 11, when the temperature in the cooler 1 is higher than the prescribed value, and the same volume of hot water is excluded out of the line 14 to control the temperature in the cooler.

WO/2013/034319	A CARBON DIOXIDE STRIPPING UREA PLANT WITH A NATURAL-CIRCULATION SYNTHESIS LOOP AND A METHOD FOR RETROFITTING SUCH PLANT.
JPS585904	[Title of the Invention] Guanidine and a manufacturing method of the salts

KAWABE TOYOTARO
ITAYA MASATO
SHIMADA AKIRA
INOE SHIGERU
FUJII HIDETSUGU

JP24888885A

October 05, 1992

November 08, 1985

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MITSUI TOATSU KAGAKU KK
TOYO ENJINIARINGU KK

C07C273/04; C07C67/00; C07C239/00

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