A Thermally-Regenerated Solid Amine CO2 Removal System Incorporating Water Vapor Recovery and Ullage Air Recovery

Date

2019-07-07

Journal Title

Journal ISSN

Volume Title

Publisher

49th International Conference on Environmental Systems

Abstract

The Thermal Amine Scrubber (TAS) flight experiment was developed under contract with NASA/JSC with the goal to demonstrate a TRL5 prototype advanced carbon dioxide (CO2) removal system based on a thermally-regenerated solid amine adsorbent. The TAS was designed to fit within two double lockers within an ISS Express Rack, consisting of a Water Save Subsystem (WSS), a CO2 Removal Subsystem (CRS), and an ISIS drawer for the system controller. The WSS incorporates a passive water save desiccant canister technology capable of recovering ~90% of the incoming humidity present in the process air stream. A supplemental desiccant wheel boosts the overall water recovery to ~97%. The CRS receives dry air from the WSS and splits flow between two pairs of CO2 removal beds containing the solid amine. Each pair of beds is restricted to 1 adsorbing bed and 1 desorbing bed, the latter of which is isolated from the process air and exposed to vacuum during thermal regeneration. A valve assembly redirects flow back to the regenerated bed at a regular interval, but first ~96% of the ullage air from the previous adsorbing bed is evacuated using a scroll compressor in an intermediary valve state. This design allows for a removal rate of ~3.7 kg/day of CO2 at 2 mmHg partial pressure CO2 in the process air, which corresponds to approximately a 4 crewmember equivalent.

The TAS will provide an additional means of removing CO2 from the ISS, potentially providing additional capacity for time periods with increased crew size. Addition of a vacuum compressor, residual water separator, and accumulator downstream of TAS will enable integration with a CO2 reduction system and is directly applicable to exploration missions requiring oxygen recovery.

Description

Holden Ranz, UTC Aerospace Systems, USA
Steven Dionne, UTC Aerospace Systems, USA
John Garr, National Aeronautics and Space Administration (NASA), USA
ICES302: Physio-chemical Life Support- Air Revitalization Systems -Technology and Process Development
The 49th International Conference on Environmental Systems was held in Boston, Massachusetts, USA on 07 July 2019 through 11 July 2019.

Keywords

CO2, amine, scrubber, vapor, air, thermal, regeneration, recovery

Citation