Systems and methods for the purification of ammonia using adsorption media

Abstract

A system and method for the purification of ammonia from an ammonia liquid feed stream, specifically ammonia regenerated from a two-column SWS unit, by vaporizing the ammonia liquid feed stream to produce a very cold (potentially sub-freezing) ammonia vapor stream and passing the cooled ammonia vapor stream through an adsorption medium, such as activated carbon, to remove impurities from the cooled ammonia vapor stream to produce a purified ammonia vapor stream.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims priority to U.S. Provisional Application No. 63 / 509,459, filed June 21, 2023, and incorporated herein by reference. This application, as well as U.S. Patent Nos. 10,022,650, 10,702,799, 10,850,226, 10,266,418, 10,456,735, 10,843,122, and 10,315,153, each of which is incorporated herein by reference, are assigned to Bechtel Energy Technologies and Solutions, Inc.

[0002] The present disclosure relates generally to systems and methods for the purification of ammonia using adsorption media. More specifically, the systems and methods improve the purification of ammonia from an ammonia liquid feed stream by vaporizing the ammonia liquid feed stream to produce a very cold (potentially sub-freezing) ammonia vapor stream, and passing the cooled ammonia vapor stream through an adsorption media, such as activated carbon, to remove impurities from the cooled ammonia vapor stream and produce a purified ammonia vapor stream. [Background technology]

[0003] There is a known problem with ammonia recovered from certain two-column sour water separator ("SWS") units; the anhydrous ammonia product has an unpleasant odor. Apparently, humans can smell some of the odor at sub-ppm levels, which exists in equilibrium with other precursors. The odor is difficult to remove because equilibrium causes its reformation. For example, if a project requires the use of recovered ammonia, the project may be forced to incinerate the reclaimed ammonia, and commercial ammonia must be purchased instead.

[0004] The detailed description is set forth below with reference to the accompanying drawings, in which like elements are referred to with like numerals, and in which: [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 5,484,582 [Patent Document 2] U.S. Patent No. 7,416,644 [Patent Document 3] U.S. Patent No. 8,968,694 [Patent Document 4] U.S. Patent No. 9,211,493 [Patent Document 5] U.S. Patent No. 10,633,307 [Patent Document 6] U.S. Patent No. 10,843,122 [Patent Document 7] U.S. Patent No. 11,635,253 [Patent Document 8] U.S. Patent No. 11,660,569 [Patent Document 9] US Patent Application Publication No. 2012 / 0118012 [Patent Document 10] US Patent Application Publication No. 2018 / 0371336 [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram depicting one embodiment of an ammonia purification system using activated carbon. DETAILED DESCRIPTION OF THE INVENTION

[0007] While the subject matter of the present disclosure has been described with particularity, this description is not intended to limit the scope of the disclosure. As such, the subject matter may be embodied in other ways, including different structures, steps, and / or combinations similar to and / or less than those described herein, in conjunction with other current or future technologies. Although the term "step" may be used herein to describe different elements of a method employed, the term should not be construed as implying any particular order between or among the various steps disclosed herein, unless expressly constrained by the description of a particular order. Other features and advantages of the disclosed embodiments will become or become apparent to those skilled in the art upon examination of the following drawings and detailed description. All such additional features and advantages are intended to be included within the scope of the disclosed embodiments. Furthermore, the depicted drawings and dimensions described herein are exemplary only and are not intended to assert or imply any limitations with respect to the environment, architecture, design, or process in which different embodiments may be practiced. To the extent that temperature and / or pressure ranges are referenced in the following description, these conditions are merely illustrative and are not meant to limit the present disclosure. All flows described herein are carried by physical lines.

[0008] The systems and methods disclosed herein address problems associated with purifying ammonia from an ammonia liquid feed stream, particularly ammonia recovered from a two-column SWS unit, by vaporizing the ammonia liquid feed stream to produce a very cold (potentially sub-freezing) ammonia vapor stream, and passing the cooled ammonia vapor stream through an adsorption medium such as activated carbon to remove impurities from the cooled ammonia vapor stream and produce a purified ammonia vapor stream.

[0009] In one embodiment, a system is disclosed for purifying ammonia, comprising: i) an ammoniacal liquid feed stream; ii) a valve in fluid communication with the ammonia liquid feed stream for vaporizing the ammonia liquid feed stream and producing a cooled ammonia vapor stream; iii) a tube containing an adsorption medium in fluid communication with the cooled ammonia vapor stream to produce a purified ammonia vapor stream.

[0010] In another embodiment, a method for the purification of ammonia is disclosed, the method comprising: i) vaporizing an ammonia liquid feed stream to produce a cooled ammonia vapor stream; ii) passing the cooled ammonia vapor stream through tubes containing an adsorption medium to remove impurities from the cooled ammonia vapor stream and produce a purified ammonia vapor stream.

[0011] Referring now to Figure 1, a schematic diagram depicts one embodiment of an ammonia purification system 100. An ammonia liquid feed stream 102 is fed through an automatic cooling valve 104, which vaporizes it by reducing pressure and thus cools it to at least 50°F, and preferably to around -30°F. The cooled ammonia liquid feed stream 106 from valve 104 may optionally be fed to a separation drum 108 to produce a cold flash vapor stream 110 and a waste liquid stream 111 if the ammonia liquid feed stream 102 is not completely vaporized and a portion (0% to 50%, more preferably 0% to 10%) of the ammonia liquid feed stream 102 is maintained as a liquid. The idea is that some of the offending molecules may not vaporize and can be removed as a liquid, so that they may be separated and disposed of.

[0012] Cold flash vapor stream 110 passes (upflow or downflow) through activated carbon tube 112, which passes through, expands, and passes through activated carbon (with or without additives) and / or other adsorbents, absorbents, or chemisorptive media such as silica gel, diatomaceous earth, any form of alumina (alpha, beta, or gamma forms; activated or inactive; with or without additives), or resins, to produce purified ammonia vapor stream 114. Purified ammonia vapor stream 114 is then fed through first compression device 116 to produce another purified ammonia vapor stream 118.

[0013] Optionally, a water stream 119 may be introduced either upstream or downstream of the first compression unit 116 to improve the quality of the final ammonia product.

[0014] The other purified ammonia vapor stream 118 and water stream 119 are then fed to an intercooler 120 to produce a two-phase fluid stream 122, which is fed to an intermediate knockout drum 124. The intermediate knockout drum 124 separates the two-phase fluid stream 122 into a concentrated waste liquid stream 126 and a partially recompressed vapor stream 128. The partially recompressed vapor stream 128 may be further compressed in a second compression unit 130 to produce a recompressed ammonia vapor stream 132. The recompressed ammonia vapor stream 132 is condensed in a condenser 134 to produce a purified ammonia stream 136, which may be collected in an accumulation drum 138. Thus, the systems and methods disclosed herein enable superior purification of recovered ammonia that would otherwise be lost due to unremoved impurities. The systems and methods disclosed herein further address issues associated with ammonia recovered from a two-column SWS unit.

[0015] While the present disclosure has been described in connection with the presently preferred embodiments, it will be understood by those skilled in the art that it is not intended to limit the disclosure to those embodiments. Accordingly, it is contemplated that various alternative embodiments and modifications can be made to the disclosed embodiments without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. [Explanation of symbols]

[0016] 100 Ammonia Purification System 102 Ammonia liquid feed stream 104 Automatic cooling valve 106 Cooled ammonia liquid feed stream 108 Separation drum 110 Cold flash steam flow 111 Disposable Liquid Flow 112 Activated carbon tube 114 Purified ammonia vapor stream 116 First Compressor 118 Other purified ammonia vapor streams 119 Water flow 120 Intercooler 122 Two-phase fluid flow 124 Intermediate knockout drum 126 Concentrated Disposable Fluid 128 Partially Recompressed Vapor Flow 130 Second Compressor 132 Recompressed ammonia vapor stream 134 Concentrator 136 Purified ammonia stream 138 Storage Drum

Claims

1. an ammonia liquid feed stream; a valve in fluid communication with the ammonia liquid feed stream for vaporizing the ammonia liquid feed stream and producing a cooled ammonia vapor stream; a tube containing an adsorption medium in fluid communication with the cooled ammonia vapor stream for removing impurities from the cooled ammonia vapor stream to produce a purified ammonia vapor stream; 1. A system for purifying ammonia, comprising:

2. 10. The system of claim 1, wherein the cooled ammonia vapor stream is cooled to a temperature of about 50°F to about -30°F using an automatic cooling valve.

3. The system of claim 1 , wherein the adsorption media comprises activated carbon.

4. 10. The system of claim 1, further comprising a separator drum positioned between the cooled ammonia vapor stream and the pipe for removing any liquid from the cooled ammonia vapor stream.

5. 10. The system of claim 1, further comprising a first compressor in fluid communication with said purified ammonia vapor stream for compressing said purified ammonia vapor stream into another purified ammonia vapor stream.

6. 6. The system of claim 5, further comprising a water stream in fluid communication with the other purified ammonia vapor stream.

7. 7. The system of claim 6, further comprising an intercooler in fluid communication with said water stream and said other purified ammonia vapor stream to produce a two-phase fluid stream comprising water and purified ammonia.

8. 8. The system of claim 7, further comprising a knockout drum in fluid communication with said two-phase fluid stream for separating said two-phase fluid stream into a concentrated waste liquid stream and a partially recompressed vapor stream.

9. 10. The system of claim 8, further comprising a second compression device in fluid communication with said partially recompressed vapor stream for compressing said partially recompressed vapor stream into a recompressed ammonia vapor stream.

10. 10. The system of claim 9, further comprising a condenser in fluid communication with the recompressed ammonia vapor stream for condensing the recompressed ammonia vapor stream into a purified ammonia stream.

11. vaporizing the ammonia liquid feed stream to produce a cooled ammonia vapor stream; passing the cooled ammonia vapor stream through tubes containing an adsorption medium to remove impurities from the cooled ammonia vapor stream and produce a purified ammonia vapor stream; 1. A method for purifying ammonia, comprising:

12. 12. The method of claim 11, wherein the cooled ammonia vapor stream is cooled to a temperature of about 50°F to about -30°F using an automatic cooling valve.

13. The method of claim 11 , wherein the adsorption media comprises activated carbon.

14. 12. The method of claim 11 further comprising removing any liquid from the cooled ammonia vapor stream.

15. 12. The method of claim 11, further comprising compressing the purified ammonia vapor stream into another purified ammonia vapor stream.

16. 16. The method of claim 15, further comprising mixing a water stream with the other purified ammonia vapor stream to produce a mixed liquid stream.

17. 17. The method of claim 16, further comprising cooling the mixed liquid stream to produce a two-phase fluid stream comprising water and purified ammonia.

18. 18. The method of claim 17, further comprising separating the two-phase fluid stream into a concentrated waste liquid stream and a partially recompressed vapor stream.

19. 20. The method of claim 18, further comprising compressing the partially recompressed vapor stream into a recompressed ammonia vapor stream.

20. 20. The method of claim 19, further comprising condensing the recompressed ammonia vapor stream into a purified ammonia stream.

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