Modular Rapid PSA System for High Purity Oxygen Production

U.S. Department of Energy is developing innovative, flexible, and small-scale (1-5 MW), modular gasification systems for converting diverse types of US domestic energy resources into value-added products with greatly reduced or negative CO2 emissions. Production of high purity (>95%) oxygen at modular scale is an enabling technology for successful development and deployment of these systems. Cryogenic air separation units are the standard commercial technology for large scale, high purity oxygen production. A cryogenic system does not scale down cost-effectively; therefore, it is not an economically viable option for modular gasification application. The commercial non-cryogenic separation for production of 10-50 ton/day of oxygen are mostly based on conventional pressure-swing adsorption (PSA) and/or vacuum-pressure-swing adsorption (VPSA) and they can produce 90-95% purity oxygen at reasonable costs (~$50 to $70 per ton), but not high-purity oxygen. This project addresses this market need. Our technology concept involves use of a 2-stage/2-layer rapid cycle PSA process using novel structured adsorbents to double oxygen productivity of a conventional PSA system thus reducing the overall capital and operating cost while producing the required high purity (>95%) for oxygen. Structured adsorbents allow high gas throughput with low pressure drop and effectively expose more gas/adsorbent contact resulting in higher mass and heat transfer and efficient adsorbent utilization, while handling target flow rates within a much smaller footprint with additional modular flexibility. In Phase 1 of this project, working with our research institute partner, Georgia Tech, we plan to synthesize and screen a number of fiber adsorbent structures. Adsorbent structures that exhibit superior performance will be tested in a lab-scale rapid PSA unit to measure their breakthrough and O2 purity through consecutive N2 and Ar selective separation performance to obtain necessary engineering design data. These results will enable a preliminary engineering design and a techno-economic analysis for a prototype pilot system to be designed, built, and tested in Phase 2. Successful demonstration at 50 kg/day scale will pave the way for the design and deployment of a 10-50 ton/day commercial modular system to meet the DOE goal for distributed power production of 1 to 5 MW, in collaboration with our industrial partner, Praxair/Linde. The anticipated benefits of the proposed technology will be development of a modular oxygen production technology for a number of industrial applications in addition to gasification and reforming of coal and other hydrocarbons, including medical oxygen supply, ozone production, refining, smelting, water purification, wastewater treatment, etc. Key factors for market acceptance and penetration of this technology will be its compact size, robustness, and lower cost of high purity oxygen production.