Process for removing NH.sub.3 from a liquid stream

• US 5,244,645 A
• Filed: 10/01/1991
• Issued: 09/14/1993
• Est. Priority Date: 10/01/1991
• Status: Expired due to Fees

• Current Assignee: Shell Oil Company (Shell Plc)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: Chu, Humbert H.
• Primary Examiner(s): LANGEL, WAYNE A
• Application Number:
  US07/769,282
• Time in Patent Office: 714 Days
• Field of Search: 423/356, 423/310, 423/313, 423/549, 423/550, 159/48.1, 159/4.01, 203/90
• US Class Current: 423/310
• CPC Class Codes: B01D 1/18 to obtain dry solids B01D1/24 takes precedence
• 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
• CPC Class Codes: C01C 1/242 Preparation from ammonia and sulfuric acid or sulfur trioxide
• CPC Class Codes: C01C 1/28 Methods of preparing ammonium salts in general
• CPC Class Codes: C02F 1/586 by removing ammoniacal nitrogen for biological methods C02F3/00

Abstract

This invention is a process for removing NH₃ from a NH₃ -containing liquid stream. The process contains the following steps: (a) passing a NH₃ -containing first liquid stream, a heated first gaseous stream, and an ammonium salt-containing second liquid stream obtained from step (d) of this process to a spray drying zone thereby spray drying the liquid stream and producing a spray drying zone effluent containing ammonia-containing gas and solid particles containing ammonium salts; (b) passing the spray drying zone effluent to a solid/gas separating means thereby separating and removing at least a portion of the solid particles and thereby producing a second gaseous stream comprising ammonia and entrained solid particles containing ammonium salts; (c) passing the second gaseous stream to a scrubbing zone to scrub the second gaseous stream, at scrubbing conditions, in the presence of an inorganic or organic acid thereby forming a gaseous stream substantially free of ammonia and an ammonium salt-containing liquid stream containing ammonium salts; and (d) passing at least a portion of the ammonium salt-containing liquid stream as the second liquid stream to the spray drying zone.

Claims

1. A process for removing NH₃ from a NH₃ -containing fist liquid stream which comprises:

(a) passing said NH₃ -containing first liquid stream, a heated first gaseous stream, and an ammonium salt containing second liquid stream obtained from step (d) of this process to a spray drying zone of between about 300°

C. and 600°

C. thereby spray drying said liquid stream and producing a spray drying zone effluent comprising ammonia containing gas and solid particles comprising ammonium slats;

(b) passing said spray drying zone effluent to a solid/gas separating means thereby separating and removing at least a portion of said solid particles nd thereby producing a second gaseous stream comprising ammonia and entrained solid particles comprising ammonium slats;

(c) passing said second gaseous stream to a scrubbing zone to scrub said second gaseous stream, at scrubbing conditions, in the presence of an acid thereby forming a gaseous stream substantially free of ammonia and an ammonium salt-containing liquid stream comprising ammonium salts;

(d) passing at least a portion of said ammonium slat-containing liquid stream containing dissolved ammonium salts as said second liquid stream to said spry drying zone.

2. The process according to claim 1 wherein the spray drying zone feed temperature is rater than about 300 and less than the decomposition temperature of said ammonium salts.

3. The process according to claim 1 wherein the spray drying zone effluent temperature is between about 100°

and 140°

C.

4. The process according to claim 1 wherein the spraying drying zone comprises an atomizer having a rotating element wherein said rotating element rotates at between about 16,000 to 24,000 revolutions per minute.

5. The process according to claim 1 wherein the first gaseous stream comprises a gas selected for eh group consisting of air, nitrogen, and mixtures thereof.

6. The process according to claim 1 wherein said NH₃ -containing fist liquid stream further comprises dissolved salts and water.

7. The process according to claim 1 wherein said acid comprises an acid selected from the group consisting of H₃ PO₄, H₂ SO₄, HCN, HCl, organic acids, and mixtures thereof.

8. The process according to claim 1 wherein said solid/gas separating mean is a cyclone.

9. A process comprising:

(a) passing a feed liquid stream containing ammonia and dissolved salts, at least a portion of a scrubber effluent liquid stream from step (d) containing dissolved ammonium slats, and a feed gaseous stream containing nitrogen and/or air to a spray dryer;

(b) spray drying said combined stream wherein said spray dryer is operated at a temperature between about 300°

C. ad 600°

C. thereby producing a spray drying zone effluent containing ammonia and solid ammonium slats;

(c) feeding said spry dryer effluent to a cyclone thereby separating solids from gas in said spray dryer effluent thereby producing a slids cyclone effluent containing solid ammonium salts and a gaseous stream containing ammonia; and

(d) feeding said gaseous stream containing ammonia to a scrubber wherein said gaseous stream containing ammonia is contacted with an inorganic or organic acid under conditions such that said ammonia gets with said acid thereby forming ammonium salts and thereby producing said scrubber effluent liquid stream and a gaseous exhaust stream.

10. The process according to claim 9 wherein said spray dryer effluent temperature is between about 100°

and 140°

C.

11. The process according to claim 9 wherein the spray dryer zone comprises an atomizer having a rotating element wherein said rotating element rotates at between about 16,000 to 24,000 revolutions per minute.

12. The process according to claim 10 wherein said inorganic acid comprises acids selected from the group consisting of H₃ PO₄, H₂ SO₄, HCN, HCl, organic acids, and mixtures thereof.

13. A process for producing ammonium salts comprising:

(1) contacting in a contacting means an ammonia containing gaseous cyclone effluent from step (d) with phosphoric or sulfuric acid wherein ammonium salts are formed and a dissolved-ammonium salts/ammonia-containing liquid effluent is produced,

(2) passing at least a portion of said dissolved-ammonium salts/ammonia-containing liquid effluent and a heated air or nitrogen stream heated to 300°

C. to 600°

C. and an ammonia-containing liquid waste stream to a spray dryer comprising an atomizer having a rotating element wherein said rotating element rotates at between 16,000 to 24,000 rpm;

spray drying said dissolved-ammonium salts/ammonia-containing liquid effluent and ammonia-containing liquid waste stream thereby producing a dried ammonium salts and ammonia-containing gaseous effluent having a temperature of between 100° and

140°

C.;

(3) passing said dried ammonium salts and ammonia-containing gaseous effluent to a cyclone wherein a portion of said dried ammonium salts are removed and producing an ammonia-containing gaseous cyclone effluent, and

(4) passing said ammonia-containing gaseous cyclone effluent to said contacting means.