PROCESS FOR RECOVERING AMMONIA FROM A GASEOUS MIXTURE CONTAINING NH3 AND HCN

• US 3,718,731 A
• Filed: 10/26/1970
• Issued: 02/27/1973
• Est. Priority Date: 10/26/1970
• Status: Expired due to Term

• Current Assignee: Harrison Cornforth Carlson, Wayne Thomas Hess
• Original Assignee: Harrison Cornforth Carlson, Wayne Thomas Hess
• Inventors: Carlson, Harrison Cornforth, Hess, Wayne Thomas
• Primary Examiner(s): Vertiz, Oscar R.
• Assistant Examiner(s): Miller, Hoke S.
• Application Number:
  US05/083,727
• Time in Patent Office: 855 Days
• Field of Search: 23/196,2R,151
• US Class Current: 423/238
• CPC Class Codes: C01C 1/12 Separation of ammonia from gases and vapours as part of the ammonia synthesis process C01C1/04

Abstract

An improved process of recovering ammonia from a mixture of gases containing ammonia and hydrogen cyanide is provided. In the process, substantially all of the ammonia and a minor portion of hydrogen cyanide are absorbed in an aqueous solution of ammonium hydrogen phosphate in an absorbing zone, the resulting solution is passed into a hydrogen cyanide removal zone so as to remove absorbed hydrogen cyanide and only a minor proportion of absorbed ammonia, the substantially hydrogen cyanide free solution is passed into a stripping zone to remove the remaining available ammonia, and then the stripped ammonia is collected. The improvement in this process comprises removing the solution from the stripping zone in two streams such that one stream is leaner in ammonia than the second stream and passing both streams to the absorbing zone at a temperature within the range of 40*-70* C., the stream leaner in ammonia passed into the absorbing zone at a point where most of the ammonia has been absorbed.

Claims

2. The process of claim 1 wherein the absorbing zone is operated at a pressure within the range of 1 to 2 atmospheres and the stripping zone is operated at a pressure within the range of 1 to 2.5 atmospheres.

3. The process of claim 2 wherein the temperature of the ammonia-lean stream and the temperature of the ammonia-rich stream is within the range of 40* C. up to 55* C.

4. The process of claim 3 wherein the ammonia-rich stream has a ratio of ammonia to phosphate within the range of 1.5 to 1.6.