| 摘要 |
Process for preparing urea, in which process - a urea and carbamate-containing urea synthesis solution is formed from NH3 and CO2, - carbamate is decomposed by the supply of heat using high-pressure steam and the decomposition products are removed from the urea synthesis solution, while steam condensate is formed in the process, - the resulting urea-containing solution is concentrated by evaporation, product urea is recovered and the vapour phase obtained in the process is condensed to form process condensate, - the process condensate is treated for the decomposition of the urea present and for the removal of NH3 and CO2, while a flow of waste water is obtained containing traces of urea and NH3, this process being characterized in that the flow of waste water is at least partly converted into contaminated low-pressure steam, this low-pressure steam is utilized in the urea process, with for mation of contaminated condensate, this condensate is subjected to a flash treatment and the condensate remaining after the flash treatment is carried off and utilized as boiler feed water.
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