Process For The Removal Of Ammonia From An Ammonia-Containing Gas Stream

• US 20080128291A1
• Filed: 11/11/2005
• Published: 06/05/2008
• Est. Priority Date: 12/08/2004
• Status: Active Grant

• Current Assignee: Stamicarbon B.V. (MAIRE), ThyssenKrupp Industrial Solutions AG (Thyssenkrupp AG)
• Original Assignee: ThyssenKrupp Industrial Solutions AG (Thyssenkrupp AG)
• Inventors: Meessen, Jozef I., Erben, Axel, Liebig, Winfried, Krijgsman, John
• Granted Patent: US 8,808,517 B2
• Time in Patent Office: Days
• US Class Current: 205/551
• CPC Class Codes: B01D 53/58 Ammonia
• CPC Class Codes: B01D 53/73 After-treatment of removed components
• CPC Class Codes: B01D 61/423 comprising multiple electrodialysis steps
• CPC Class Codes: B01D 61/44 Ion-selective electrodialysis
• CPC Class Codes: B01D 61/445 with bipolar membranes; Water splitting
• CPC Class Codes: C02F 1/4693 electrodialysis
• CPC Class Codes: C02F 2101/16 Nitrogen compounds, e.g. ammonia
• CPC Class Codes: C02F 2103/18 from the purification of gaseous effluents
• CPC Class Codes: C07C 273/14 Separation; Purification; Stabilisation; Use of additives
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

The invention is directed to a process for the removal of ammonia from an ammonia-containing gas stream by treating the ammonia in the ammonia-containing gas stream with an acid, during which treatment an aqueous stream comprising an ammonium salt, wherein the aqueous stream comprising the ammonium salt is treated with electrodialysis, whereby the acid is recovered and an aqueous stream comprising an ammonium hydroxide salt is formed.

Claims

1. Process for the removal of ammonia from an ammonia-containing gas stream by treating the ammonia in the ammonia-containing gas stream with an acid, during which treatment an aqueous stream comprising an ammonium salt is formed, characterized in that the aqueous stream comprising the ammonium salt is treated with electrodialysis, whereby the acid is recovered and an aqueous stream comprising an ammonium hydroxide salt is formed.

2. Process according to claim 1, characterized in that the aqueous stream comprising an ammonium hydroxide salt is heat treated, whereby a gaseous ammonia stream is formed.

3. Process according to claim 1, characterized in that the ammonia-containing gas stream is an off-gas stream from a prilling or granulation section of a process for the production of urea.

4. Process according to claim 1, characterized in that the gaseous ammonia stream is recycled to the process for the production of urea.

5. Process according to claim 1, characterized in that the electrodialysis is performed in an electrochemical cell comprising an anode and cathode separated by an anion-permeable membrane, a cation-permeable membrane or a combination of one or more of these membranes with at least two bipolar membranes.

6. Process according to claim 1, characterized in that the electrodialysis is performed in an electrochemical cell comprising an anode and cathode separated by an anion-permeable membrane.

7. Process according to claim 1, characterized in that the electrodialysis is performed in an electrochemical cell comprising an anode and cathode separated by an anion-permeable membrane, a cation-permeable membrane and bipolar membranes.

8. Electrodialysis section comprising

a scrubber, wherein an ammonia-containing gas stream is contacted with an acid,

an electrodialysis apparatus, wherein a stream comprising an acid and a stream comprising an ammonium hydroxide salt are generated.

9. Electrodialysis section according to claim 8, characterized in that the electrodialysis section also comprises a stripper wherein the stream comprising an ammonium hydroxide salt is heated and a gaseous ammonia stream is formed.

10. Urea plant comprising a prilling section or a granulation section, characterized in that the urea plant also comprises an electrodialysis section according to claim 9 to treat the ammonia-containing gas stream leaving the prilling or granulation section.

11. Urea plant according to claim 10, characterized in that the gaseous ammonia stream formed in the electrodialysis section is recirculated within the urea plant.