U.S. patents available from 1976 to present.
U.S. patent applications available from 2005 to present.

Method of quantitatively producing ammonia from urea

Patent 6887449 Issued on May 3, 2005. Estimated Expiration Date: Icon_subject November 21, 2022. 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.

Patent References

3826815

3900544

3922222

Method of hydrolyzing urea contained in waste water streams
Patent #: 4087513
Issued on: 05/02/1978
Inventor: Schell

Catalytic method for hydrolyzing urea
Patent #: 4168299
Issued on: 09/18/1979
Inventor: Schell

Urea reduction of NOx in combustion effluents
Patent #: 4208386
Issued on: 06/17/1980
Inventor: Arand ,   et al.

Reduction of nitrogen oxides with catalytic acid resistant aluminosilicate molecular sieves and ammonia
Patent #: 4220632
Issued on: 09/02/1980
Inventor: Pence ,   et al.

Catalytic method for hydrolyzing urea
Patent #: 4220635
Issued on: 09/02/1980
Inventor: Schell

Process for the purification of urea solutions containing biuret and the like
Patent #: 4231960
Issued on: 11/04/1980
Inventor: Schmidt

Process for purifying urea-containing waste water and process for preparing melamine
Patent #: 4308385
Issued on: 12/29/1981
Inventor: Goorden

More ...

Inventors

Assignee

Application

No. 10302531 filed on 11/21/2002

US Classes:

423/358From organic material containing nitrogen

Examiners

Primary: Langel, Wayne A.

Attorney, Agent or Firm

Foreign Patent References

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International Class

C01C001/08

Abstract

Methods and apparatus for continuously, quantitatively producing gaseous ammonia from urea, including the steps of: dissolving urea in water to form concentrated aqueous urea comprising at least 77 wt. % urea; continuously feeding the concentrated aqueous urea into a reactor; continuously feeding a separate, additional supply water into the reactor to form an aqueous urea reaction mixture; heating the aqueous urea reaction mixture; and continuously withdrawing a gas phase product including ammonia from the reactor, is disclosed. Also disclosed are methods and apparatus for continuous and batchwise dissolution of urea to form aqueous urea solutions.

Other References

  • Kucheryavi et al., “Kinetics of the Hydrolysis of Urea at High Temperatures in Relation to Purification of Waste Waters in Urea Manufacture”; translated from Zhurnal Prikladnoi Khimii, vol. 42, No. 7, pp. 1596-1600 (1969).
  • Blasiak et al., “Equilibrium Pressure in the System NH4CO2NH2 + H2O at High Temperatures”; Chemia Stosowana, vol. 4, No. 545, pp. 545-550 (1983), no month.
  • Makansi, Jason Ed.; “Ammonia: It's coming to a plant near you”; Power pp. 20-22 (May, 1992).
  • Smith et al., “Integrated Dry NOx/SOx Emissions Control System Low-NOx Combustion System SNCR Test Report,” Public Service Company of Colorado, DOE Contract No. DE-FC22-91 PC90550 (Jun. 1994).
  • International Preliminary Examination Report (PCT) Application No. PCT/US98/05708 dated May 11, 1999, believed to be publicly available Oct., 1999.
  • Hunt et al., “Selective Non-Catalytic Operating Experience Using Both Urea and Ammonia” 1993 Joint Symposium on Stationary Combustion Nox, Control (May 1993).
  • Dr.-Ing. Ulrich Neumann; “Drei trockene Typen Das DENOX-Verfahren von Hitachi”; (Three Dry Types—The DeNOx Process from Hitachi), Engergie (Apr., 1986).
  • International Search Report for PCT/US02/09294 mailed Aug. 7, 2002.
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