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PROCESS AND PLANT FOR THE PRODUCTION OF UREA WITH HIGH CONVERSION YIELD AND LOW ENERGY CONSUMPTION
PROCESS AND PLANT FOR THE PRODUCTION OF UREA WITH HIGH CONVERSION YIELD AND LOW ENERGY CONSUMPTION
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机译:高转化率低能耗尿素生产工艺及装置
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摘要
The present invention relates to a process for the preparation of urea by reacting ammonia with carbon dioxide in a reaction space to obtain a reaction mixture comprising urea, urea and free ammonia in aqueous solution, treating the mixture to partially decompose the aqueous urea and partially separating the free ammonia. receiving a first stream containing carbon dioxide in a vapor phase, a stream containing urea and a carbamate residue in aqueous solution, subjecting the first stream containing ammonia and carbon dioxide in a vapor phase to at least partial condensation to a solution of urea in an aqueous solution, a stream of material is fed to a urea recovery section where the carbamate residue is separated from the urea so that an aqueous solution a second carbamate moiety, the process further comprising: subjecting at least a portion of the second aqueous carbamate moiety obtained in the recovery phase to a partial decomposition of a second vapor phase containing a second stream of ammonia and carbonate and an a second stream of ammonia and carbon dioxide in vapor phase is subjected to at least partial condensation to obtain a third portion of the carbamate in aqueous solution, the third portion of the carbamate being recycled to the reaction space. The present invention also relates to a urea production plant comprising a single urea synthesis reactor (1), a first stripping unit (2), said process for the partial decomposition of the reaction mixture leaving the said reactor (1) and partially separating the free ammonia present in said aqueous solution. means (6) for partially condensing the vapor leaving the first stripping unit (2) and returning the carbamate top portion of the aqueous solution to said reactor (6), a residual carbamate containing urea containing material leaving said first stripping unit (2) and (3, 4, 7, 8) for separating the urea produced in the reactor (1) from a second fraction of carbamate in aqueous solution, characterized in that a second stripping unit (9) is provided in the aqueous solution. at least a portion of the vapors leaving said second stripping unit (9)
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