Method of removing ammonia from ammonia containing liquor

• US 3,920,419 A
• Filed: 04/10/1974
• Issued: 11/18/1975
• Est. Priority Date: 04/10/1974
• Status: Expired due to Term

• Current Assignee: LTV Steel Company, Inc. (LTV Corp.)
• Original Assignee: Anthony C. Naso, James W. Schroeder
• Inventors: Schroeder, James W., Naso, Anthony C.
• Primary Examiner(s): Adee, John
• Assistant Examiner(s): Cross, Ethel R.
• Application Number:
  US05/459,461
• Time in Patent Office: 587 Days
• Field of Search: 55/18,30,53,54,19,70,69,20,226 423/356,357
• US Class Current: 95/9
• CPC Class Codes: C01C 1/10 Separation of ammonia from ammonia liquors, e.g. gas liquors as part of the ammonia synthesis process C01C1/04

Abstract

Free and fixed ammonia values are removed from ammonia liquor by a process which in the preferred embodiment includes the characterizing steps of: (1) automatically adjusting the pH of the liquor by the continuously controlled addition of caustic soda solution in an amount sufficient to maintain a minimum pH of 10.5, (2) stripping ammonia from the liquor by counterflowing air through a packed column at a temperature of from 140*-180*F., and (3) controlling the flow of the air in direct relation to the amount of feed liquor so that at least 99% of the ammonia is removed from the liquor, the most preferred flow rate of the air being in the range of from about 50-100 cubic feet per gallon of feed liquor. The ammonia containing air is withdrawn from the column and the ammonia is extracted from the air in an acid absorber, preferably using a sulfuric acid solution having a pH of from 0.5-1.5. The air from the acid absorber is recycled to the column in a closed system.

Claims

1. A METHOD OF REMOVING AMMONIA FROM AN AMMONIA CONTAINING LIQUOR COMPRISING THE STEPS OF:

A. FEEDING THE LIQUOR TO THE TOP OF A PACKED COLUMN;

B. AUTOMATICALLY MONITORING THE PH OF THE FEED LIQUOR;

C. AUTOMATICALLY ADDING CAUSTIC SODA IN CONTROLLED AMOUNTS TO THE FEED LIQOUR PRIOR TO INTRODUCTION INTO THE COLUMN TO MAINTAIN A MINIMUM PH OF 10.5;

D. COUNTERFLOWING A GASEOUS STRIPPING MEDIAN THROOUGH THE COLUMN AT THE MINIMUM TEMPERATURE OF ABOUT 140*F;

2. A method as claimed in claim 1 in which the flow rate of the stripping median is controlled to be at least 40 cubic feet per gallon of feet liquor.

3. A method as claimed in claim 4 including the steps of:

e. withdrawing ammonia containing air from the column;

f. removing the ammonia from the air; and

g. thereafter recycling the air to the column in a closed system for further stripping of ammonia.

4. A method of removing ammonia from an ammonia containing liquor comprising the steps of:

a. feeding the liquor to an extraction column;

b. automatically monitoring the pH of the feed liquor;

c. automatically adding caustic soda solution to the feed liquor prior to introduction into the column to maintain a minimum pH of 10.5;

d. counterflowing air through the column at a flow rate controlled to be at least about 40 cubic feet per gallon of feet liquor to strip the ammonia; and

e. automatically sensing the operating temperature of the column and heating the air to maintain the operating temperature in a range from about 140*-180* F.

5. A method as claimed in claim 4 including the steps of:

f. withdrawing ammonia containing air from the column;

g. extracting the ammonia from the air by acid absorption; and

h. recycling the air to the column in a closed system.

6. A method of removing ammonia from an ammonia containing liquor comprising the steps of:

a. feeding the liquor to the top of a packed column;

b. automatically monitoring the pH of the feed liquor and maintaining the pH in a range of from 10.5-11.5 by the controlled addition of caustic Soda solution prior to introducing the liquor into the column;

c. counterflowing air through the column at a rate controlled to be at least at about 40 cubic feet per gallon of feet liquor to strip the ammonia;

d. withdrawing liquid effluent from the bottom of the column; and

e. maintaining the operating temperature of the column in the range from about 140*-180*F by automatically heating the air in response to the temperature of the liquid effluent.

7. A method of removing ammonia from an ammonia containing liquor comprising the steps of:

a. adjusting the pH of the liquor to at least 10.5 by the addition of caustic soda solution;

b. feeding the liquor of adjusted pH to the top of a packed column;

c. controlling air through the column at a rate of at least about 40 cubic feet per gallon of feet liquor to strip the ammonia;

d. maintaining the operating temperature of the column in a range from about 140*-180*F. e. conducting ammonia containing air from the column to a sulfuric acid absorber; and

f. extracting ammonia from the air in the absorber with sulphuric acid solution having a pH of at least about 0.5.

8. A method as claimed in claim 7 including the step of recycling air from the absorber to the column in a closed system for further stripping.

9. A method as claimed in claim 7 including the step of blowing down an effluent solution from the absorber having an ammonium sulfate concentration of from 20-35% by weight.

10. A method of removing ammonia from an ammonia containing liquor comprising the steps of:

a. automatically adjusting the pH of the liquor to a range of from 10.5-11.5 by monitoring the pH and controllably adding caustic soda solution in response to the monitored pH;

b. feeding the liquor to the top of a packed column;

c. counterflowing air through the column at a flow rate of at least about 40 cubic feet per gallon of feet liquor to strip the ammonia;

d. withdrawing liquid effluent from the column;

e. maintaining and operating temperature in the column from about 140*-180*F. by heating the air in response to the temperature of the effluent;

f. withdrawing ammonia containing air from the column and conducting it to a sulfuric acid absorber;

g. extracting ammonia from the air in the absorber with a sulfuric acid solution adding a pH of at least about 0.5; and

h. recycling air from the absorber to the column in a closed system.

11. A method as claimed in claim 10 including the step of blowing down an effluent solution from the absorber having an ammonium sulfate concentration of from 20-35% by weight.