Systems and methods for basic gas recovery, acid gas separation, or combination thereof
The present invention relates to processes and systems for basic gas, e.g., ammonia, recovery and/or acid-gas separation. In some embodiments, a system for acid gas separation may be integrated with an ammonia abatement cycle employing a high temperature absorber. In some embodiments, a system for acid gas separation may employ a higher temperature absorber due to the lower energy consumption and cost of the integrated ammonia abatement cycle. Advantageously, heat may be recovered from the absorber to power at least a portion of any acid gas desorption in the process. Reverse osmosis or other membranes may be employed.
1. A process for separating or recovering basic gases comprising:
(a) absorbing ammonia from an ammonia containing gas stream into an ammonia-lean, an ammonia-ultra-lean, or ammonia free solution, to form an ammonia-rich solution;
(b) enriching said ammonia-rich solution with one or more acid gases to form an ammonia-rich, acid gas rich solution; and
(c) concentrating said ammonia-rich, acid gas rich solution using one or more membranes to form a first retentate and a permeate wherein said permeate is suitable for use as at
least a portion of the ammonia-ultra-lean or ammonia-free solution in step (a); and
d) adding said first retentate to a larger volume of ammonia-acid gas solution to form a first combined solution; and
e) further concentrating said first combined solution using a membrane to form a second retentate and a second permeate wherein the second permeate comprises an amount of water that is the same or greater than an amount of water in the first retentate.
2. The process of claim 1 further comprising:
using at least a portion of said second permeate as at least a portion of the ammonia-ultra-lean or ammonia-free solution in step a).
3. The process of claim 1 further comprising:
precipitating an ammonia-acid gas salt from said second retentate e).
4. The process of claim 3 further comprising:
removing at least a portion of said precipitate to form a solution.
5. The process of claim 4 further comprising:
using at least a portion of said solution as the larger volume of ammonia-acid gas solution in d).
6. The process of claim 4 wherein said ammonia containing gas stream comprises one or more other basic gases.
7. The process of claim 4 further comprising absorbing an acid gas with the ammonia to form an acid gas rich, ammonia-rich solution.
8. The process of claim 7 wherein an acid gas is desorbed from said acid gas rich, ammonia-rich solution to form an acid gas lean, ammonia-rich solution and desorbed acid gas.
9. The process of claim 4 wherein the ammonia containing gas stream further comprises an acid gas.