| 摘要 |
<p>Process for the removal of urea, ammonia and carbon dioxide from dilute aqueous solutions, obtained as process condensates in coupled ammonia and urea syntheses, by hydrolysis of urea and desorption of ammonia and carbon dioxide. Process condensate poor in ammonia is treated with steam in a reaction column at a pressure of 15-42 bar and a temperature of 200-320°C, a gas mixture containing ammonia, carbon dioxide and water is carried off from the top of the reaction column and an aqueous liquid virtually free of urea, ammonia and carbon dioxide is carried off from the bottom of the reaction column. Prior to the treatment in the reaction column, ammonia and carbon dioxide are removed, at a pressure of 1-5 bar, from the process condensate of the urea synthesis. Preferably the quantity of ammonia in the process condensate to be treated is reduced to less than 0.3% by weight.</p> |
