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(475a) Hybrid Membrane-PSA System for Efficient Oxygen Generation for Transportable, Modular Gasification Systems

Authors: 
Schwartz, N. R. - Presenter, Mainstream Engineering Corporation
Cox, P., Mainstream Engineering Corporation
Blaise, M. J., Mainstream Engineering Corporation
Modular gasification systems need new low capital and operating cost approaches for the separation of O2 from air to produce high-purity O2 (>97%). Production of O2 with large-scale cryogenic distillation is costly and not scalable to small- to commercial-scale systems. The feasibility of concentrating O2 from air using a combination of targeted mixed matrix membranes (MMMs) with a process-intensified, process-integrated pressure swing adsorption (PSA) system was experimentally determined. Pre-concentrating O2 with MMMs allows the integrated PSA system to generate high-purity O2 with smaller PSA units, faster cycle times, and reduced power requirements to minimize the overall costs. High-capacity O2 sorbent materials, commercial adsorbents, and O2-selective adsorbents such as cerium-exchange zeolite, titanosilicates, and cerium-exchanged zeolite X with strontium were tested and characterized Adsorbents were characterized by BET analysis, energy-dispersive X-ray (EDX) spectroscopy, X-ray power diffraction (XRD), and equilibrium adsorption isotherm measurements. Porous asymmetric MMMs with high selectivity and permeability were synthesized using glassy polyimides, polyether sulphone (PES), and polyvinyl acetate and then modified with a thin layer of a zeolite or silicate nanomaterial. The nanomaterials were combined with a high permeability glassy polymer such as Poly (1-trimethylsilyl-1-propyne) (PTMSP) to form an asymmetric membrane onto a porous substrate (e,g, PES). A range of inorganic fillers (e.g., clays, zeolites, aluminosilicates) were used to evaluate selectivity and permeability. The effects of the membrane thickness, porosity, inorganic material loading, and operating conditions were determined. Lastly, a pilot-scale PSA system was operated using an O2-enriched stream representative of the membrane-based concentrator to demonstrate the combined membrane-PSA approach. The incoming, O2-enriched air was varied to determine the effects of O2 concentration, temperature, pressure, and other process parameters on the total power and energy for operation, separation efficiency, and effluent gas O2 concentration.