Process for the removal of urea, ammonia, and carbon dioxide from dilute aqueous solutions

Patent 4456535 Issued on June 26, 1984. Estimated Expiration Date:

November 30, 2001. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

Urea hydrolysis Patent #: 4341640
Issued on: 07/27/1982
Inventor: Landis

Inventors

Application

No. 06/325922 filed on 11/30/1981

US Classes:

210/750, Including degassing210/752, Plural spaced feedings210/766, Including temperature change210/774, Including temperature change564/73, Purification or recovery95/246And reduction of pressure (e.g., flashing, etc.)

Examiners

Primary: Castel, Benoit

Attorney, Agent or Firm

Cushman, Darby & Cushman

International Classes

C07C 273/00 (20060101)
C07C 273/04 (20060101)
C02F 1/02 (20060101)
C02F 1/04 (20060101)
C02F 1/58 (20060101)
C02F 9/00 (20060101)

Foreign Application Priority Data

1980-11-28 NL

Abstract

An improved process for the removal of urea, ammonia, and carbon dioxide from dilute aqueous solutions thereof by hydrolyzing the urea, and thereafter desorbing ammonia and carbon dioxide. The dilute solution containing urea is passed into the top portion of a reaction column and caused to flow downward and countercurrent to a heating and stripping gas while maintaining the reaction column at a pressure of between about 10 and 30 bar, and a top column temperature of between about 170° and 220° C. and a bottom column temperature of between about 180° and 230° C. The resulting liquid stream removed from the bottom of the reaction column, comprised of a substantially urea-free aqueous solution of ammonia and carbon dioxide, is introduced into a desorption zone wherein, at a pressure of between about 1 and 5 bar, ammonia and carbon dioxide are removed therefrom.