| 摘要 |
PURPOSE:To carry out hydrolysis of urea economically, by allowing aq. soln. contg. urea, ammonia, and CO2 in the first stage to contact concurrently with pressurized steam, and in the second stage countercurrently with steam. CONSTITUTION:In a process for hydrolyzing urea contained in aq. soln. contg. a trace amt. of urea, ammonia, and CO2 to hydrolyze the urea to ammonia and CO2, and to obtain water contg. no urea, ammonia, nor CO2, the hydrolysis of urea is carried out in two stages. In the first stage, the aq. soln. is allowed concurrently to contact with pressurized steam in a hydrolyzer 12L until the content of residual urea attains 50-500ppm, thus, ammonia and CO2 produced by the hydrolysis are separated in gaseous form. Aq. soln. contg. the residual urea is further allowed to contact countercurrently in a hydrolyzer 12R in the second stage with steam under the same pressure as in the first stage. Thus, residual urea is further hydrolyzed, and produced ammonia and CO2 are separated in the gaseous form, and water contg. substantially no urea is obtd.
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