Rebreathers are scuba gear that allow the diver to breath underwater without producing bubbles. They have many benefits including light-weight, reduced risk of decompression (lack of nitrogen in the system allows the divers to stay submerged longer) and stealth (since they produce no bubbles, they dont reveal the divers location). In this closed-circuit operation, the CO2 is removed from the exhaled gas with an absorbent such as Sofnolime (soda lime, a mixture of sodium hydroxide and calcium oxide). The use of expendable sorbent limits the duration of the dives and also generate a supply burden. TDA Research Inc. (TDA) proposes to develop a regenerable CO2 removal system for closed-circuit scuba rebreathers that can achieve a high CO2 uptake and regenerated with a very low heat input. The CO2 is removed at 15-25oC range at 2,500 ppmv (max) and recovered at 60-80oC range as a pure product at ~1 atm (gauge) which will be dissolved in sea water and released from the gear without forming bubbles (i.e., not generating a detectable acoustic signature).
Benefit: A high CO2 capacity, regenerable sorbent rebreather system would enable diving gear that is lighter weight and allows longer dives to greater depths with no bubbles to reveal the divers presence. Applications include diving systems for military and commercial/recreational diving, life support systems for underwater manned vehicles, underwater facilities, submarines and other enclosed spaces. A high performing CO2 sorbent could also be used for CO2 removal from flue gas and direct air capture, pre-purification before air separation (PPU), syngas treatment, natural gas upgrading, anesthesia machine and confined spaces such as the space shuttle.
Keywords: CO2 scrubber, CO2 scrubber, Life support system, Thermal swing, regenerable
