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Abstract

In a process for producing ammonia from urea which process comprises:

(a) heating a liquid phase reaction medium comprising an aqueous solution of urea, or a mixture of urea, containing biuret or ammonium carbamate on site, in a hydrolysis reactor such that a pressurized gaseous ammonia and carbon dioxide-containing product is obtained which is essentially free of urea, biuret, or ammonium carbamate;(b) separating the gaseous ammonia and carbon dioxide-containing product from the liquid phase reaction medium at the prevailing pressure;(c) retaining the liquid phase reaction medium in the reactor for further conversion to gaseous ammonia and carbon dioxide, and/or recycling at least a portion of the said reaction medium back into the reactor, a urea dissolver, or feed solution to the reactor for further conversion; and(d) withdrawing the gaseous ammonia and carbon dioxide-containing product separated in step (b) at a controlled rate to meet varying ammonia demand requirements;the improvement wherein the operating pressure of said reactor is set or adjusted such that excess water for the reaction is maintained in the reactor and the dew-point of said gaseous ammonia and carbon-dioxide-containing product is below the operating temperature of said reactor.

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First Claim