Xenon recovery system
View Patent ↗A first aspect of a process of recovering xenon from feed gas includes: providing an adsorption vessel containing adsorbent having a Xe/N 2 selectivity ratio <75; feeding into the adsorption vessel feed gas having an initial nitrogen concentration >50% and an initial xenon concentration ≧0.5%; evacuating the adsorption vessel; and purging the adsorption vessel at a purge-to-feed ratio ≧10. The final xenon concentration is ≧15× the initial xenon concentration. A second aspect of the process includes providing an adsorption vessel containing adsorbent having a Xe Henry's law Constant ≧50 mmole/g/atm; feeding into the adsorption vessel feed gas having an initial nitrogen concentration >50% and an initial xenon concentration ≧0.5%; heating and purging the adsorption vessel to recover xenon having a final concentration ≧15× its initial concentration. Apparatus for performing the process are also described.
1. A process of recovering xenon from a feed gas, said process comprising the steps of:
providing an adsorption vessel containing an adsorbent having a Xe/N2 selectivity ratio of less than 75;
feeding a feed gas into the adsorption vessel, wherein the feed gas comprises an initial concentration of nitrogen greater than 50% and an initial concentration of xenon of at least 0.5%;
evacuating the adsorption vessel by reducing a pressure of the adsorption apparatus below atmospheric pressure to recover a first xenon-enriched gas;
purging the adsorption vessel at a purge to feed ratio of at least 10 to recover a second xenon-enriched gas; and
combining the first xenon-enriched gas and the second xenon-enriched gas to provide a product gas comprising a final concentration of xenon at least 15 times greater than the initial concentration of xenon.
2. The process of claim 1 , further comprising repressurizing the adsorption vessel after the purging step and repeating the steps of the process at least once.
3. The process of claim 1 , further comprising condensing and cooling the product gas, and removing an additional amount of nitrogen gas from the product gas to provide a solid or liquid product comprising xenon.
4. The process of claim 1 , wherein the feed gas comprises an effluent gas of a semiconductor-related manufacturing process.
5. The process of claim 4 , wherein the effluent gas comprises Xe and at least one member selected from the group consisting of HF, F 2 , H 2 O, C 4 F 6 , O 2 , CO 2 , COF 2 , XeF 2 , CF 4 and SiF 4 , is passed through a surge vessel to adsorb at least one of H 2 O, CO 2 , and fluorinated molecules from the effluent gas, and is diluted with N 2 to provide the feed gas for feeding into the adsorption apparatus.
6. The process of claim 1 , wherein the initial concentration of xenon is 0.5% to 5.0%.
7. The process of claim 1 , wherein the feed gas has a temperature range of 0 to 100° C. and a pressure range of 1 to 10 bara.
8. The process of claim 1 , wherein the adsorbent comprises at least one member selected from the group consisting of an alumina, a zeolite, a silica gel and an activated carbon.
9. The process of claim 1 , wherein the adsorbent consists essentially of particles having a diameter of 0.5 to 3.0 mm.
10. The process of claim 1 , wherein a xenon recovery rate is at least 80%.
11. The process of claim 1 , wherein the process is conducted in a vacuum swing adsorption apparatus containing only one adsorption vessel.
12. A xenon recovery apparatus adapted to perform the process of claim 1 , said apparatus comprising:
a surge vessel in fluid communication with a source of an effluent gas comprising Xe and at least one member selected from the group consisting of H 2 O, O 2 and CO 2 , wherein the surge vessel contains a material adapted to adsorb from the effluent gas at least one of H 2 O, O 2 and CO 2 more effectively than Xe;
an adsorption vessel in fluid communication with the surge vessel, and containing an adsorbent having a Xe/N 2 selectivity ratio of less than 75;
a nitrogen surge vessel adapted to receive nitrogen from the adsorption vessel during the evacuating step and supply nitrogen to the adsorption vessel during the purging step;
a pump adapted to evacuate the first xenon-enriched gas from the adsorption vessel;
a compressor adapted to compress the product gas;
a cold trap adapted to cool the compressed product gas so as to remove an additional amount of nitrogen gas from the product gas to provide a solid or liquid product comprising xenon; and
control electronics programmed to maintain the purge to feed ratio of at least 10.
13. A process of recovering xenon from a feed gas, said process comprising the steps of:
providing an adsorption vessel containing an adsorbent having a Xe Henry's law Constant of at least 50 mmole/g/atm;
feeding a feed gas into the adsorption vessel, wherein the feed gas comprises an initial concentration of nitrogen greater than 50% and an initial concentration of xenon of at least 0.5%;
heating the adsorbent to a temperature of at least 100° C. to recover a first xenon-enriched gas;
purging the adsorption vessel to recover a second xenon-enriched gas;
combining the first xenon-enriched gas and the second xenon-enriched gas to provide a product gas comprising a final concentration of xenon at least 15 times greater than the initial concentration of xenon; and
repressurizing the adsorption vessel after the purging step and repeating the steps of the process at least once.
14. The process of claim 13 , further comprising condensing and cooling the product gas, and removing an additional amount of nitrogen gas from the product gas to provide a solid or liquid product comprising xenon.
15. The process of claim 13 , wherein the feed gas comprises an effluent gas of a semiconductor-related manufacturing process.
16. The process of claim 15 , wherein the effluent gas comprises Xe and at least one member selected from the group consisting of HF, F 2 , H 2 O, C 4 F 6 , O 2 , CO 2 , COF 2 , XeF 2 , CF 4 and SiF 4 , is passed through a surge vessel to adsorb at least one of H 2 O, CO 2 , and fluorinated molecules from the effluent gas, and is diluted with N 2 to provide the feed gas for feeding into the adsorption apparatus.
17. The process of claim 13 , wherein the initial concentration of xenon is 0.5% to 5.0%.
18. The process of claim 13 , wherein the feed gas has a temperature range of 0 to 100° C. and a pressure range of 1 to 10 bara.
19. The process of claim 13 , wherein the adsorbent comprises at least one member selected from the group consisting of an alumina, a zeolite, a silica gel and an activated carbon.
20. The process of claim 13 , wherein the adsorbent consists essentially of particles having a diameter of 0.5 to 3.0 mm.
21. The process of claim 13 , wherein the heating step comprises raising the temperature of the adsorbent to 100-300° C.
22. The process of claim 13 , wherein the process is conducted in a temperature swing adsorption apparatus containing only one adsorption vessel.
23. The process of claim 13 , wherein a xenon recovery rate is at least 80%.
24. A xenon recovery apparatus adapted to perform the process of claim 13 , said apparatus comprising:
a surge vessel in fluid communication with a source of an effluent gas comprising Xe and at least one member selected from the group consisting of H 2 O, O 2 and CO 2 , wherein the surge vessel contains a material adapted to adsorb from the effluent gas at least one of H 2 O, O 2 and CO 2 more effectively than Xe;
an adsorption vessel in fluid communication with the surge vessel, and containing an adsorbent having a Xe Henry's Constant of at least 50 mmole/g/atm;
a heater adapted to heat the adsorption vessel;
a nitrogen surge vessel adapted to receive nitrogen from the adsorption vessel during the heating step and supply nitrogen to the adsorption vessel during the purging step;
a compressor adapted to compress the product gas;
a cold trap adapted to cool the compressed product gas so as to remove an additional amount of nitrogen gas from the product gas to provide a solid or liquid product comprising xenon; and
control electronics programmed to adjust the heater to maintain the temperature of the adsorption vessel at 100° C. or more.