Low energy, high recovery, rapid cycle kinetic PSA for biogas
Disclosed herein are embodiments of a rotary gas separation device, such as a rotary pressure swing adsorption device. The rotary pressure swing device can include, for example, a rotor with a plurality of adsorber elements, a stator with a plurality of conduits, and a rotary valve comprising a seal assembly positioned between the rotor and the stator.
1. A method of making an adsorbent structure for a pressure swing adsorption apparatus wherein the adsorbent structure comprises an adsorbent sensitive to sudden increases or decreases in water content, the method comprising:
preparing a slurry of the sensitive adsorbent and water;
coating a substrate with the aqueous slurry; and
drying the coated substrate to produce the adsorbent structure wherein the drying comprises first, second, and third drying stages in sequence wherein the rate of drying in the second drying stage is slower than that in the first drying stage and the rate of drying in the first drying stage is slower than that in the third drying stage.
2. The method of claim 1 wherein the slurry comprises up to 50% by weight of water.
3. The method of claim 1 wherein the first drying stage comprises using a drying rate that removes less than or equal to 30% weight of water per minute.
4. The method of claim 1 wherein the first drying stage comprises drying at less than or equal to 40° C. on exit of a dryer.
5. The method of claim 1 wherein the first drying stage comprises removing 25 to 30% of the water in the coated substrate before drying is discontinued.
6. The method of claim 1 wherein the second drying stage comprises using a drying rate that removes less than or equal to 5% weight of water per day.
7. The method of claim 1 wherein the second drying stage comprises drying at ambient temperature.
8. The method of claim 1 wherein the second drying stage comprises removing 5 to 10% of the water in the coated substrate before drying is discontinued.
9. The method of claim 1 wherein the third drying stage comprises using a drying rate that removes greater than or equal to 10% weight of water per minute.
10. The method of claim 1 wherein the third drying stage comprises drying at a temperature above 130° C.
11. The method of claim 1 wherein the third drying stage comprises removing 5 to 10% of the water in the coated substrate before drying is discontinued.
12. The method of claim 1 wherein up to 10% of the water in coated substrate remains in the adsorbent in the adsorbent structure after drying.
13. The method of claim 1 additionally comprising exposing the sensitive adsorbent to water vapor before preparing the slurry, thereby slowly adding water to the adsorbent before preparing the slurry.
14. The method of claim 13 wherein from about 20% to 30% by weight water is adsorbed by the sensitive adsorbent.
15. The method of claim 13 wherein the water vapor is ambient humid air.
16. The method of claim 13 wherein the exposing takes place over a period of from about 4 to 7 days.
17. The method of claim 1 wherein the substrate is a sheet and the adsorbent structure is a laminated sheet.