449569 Poster-Membrane Process Optimization for Carbon Capture
449569 Poster-Membrane Process Optimization for Carbon Capture
Monday, May 23, 2016
Evergreen Ballroom (Hyatt Regency Bellevue)
Membrane Process Optimization for Carbon Capture
Norfamila Che Mat and Glenn Lipscomb
Chemical and Environmental Engineering Department
University of Toledo
Key Words: carbon dioxide, Post-combustion CO2 capture, hollow fiber membrane
Concerns over the effects of anthropogenic carbon dioxide (CO2) emissions from fossil-fuel electric power plants has led to significant efforts in the development of processes for CO2capture from flue gas. Options under consideration include absorption, adsorption, membrane, and hybrid processes.
The US Department of Energy (DOE) has set goals of 90% CO2 capture at 95% purity followed by compression to 140 bar for transport and storage. Ideally, the levelized cost of electricity (LCOE) would increase by no more than 35%.
Membrane Technology and Research, Inc. (MTR) has proposed a promising design that combines membrane capture with cryogenic condensation [JMS 359 (2010) 126-239]. The process utilizes a two-stage membrane process in which the feed air to the furnace sweeps the flue gas in the second stage to reduce the flow of CO2 in the effluent to 10% of that leaving the furnace. Such a design significantly reduces capture costs but leads to a detrimental reduction in the oxygen concentration of the feed air to the boiler.
The transport properties and operating pressures of the membrane stages are optimized in this study. Membrane selectivity is varied over a broad range encompassing the values considered by MTR. Permeability is varied with selectivity according to the variation anticipated by the upper bound of the Robeson plot for CO2 and nitrogen. Membrane permeance is calculated assuming membranes can be fabricated with an effective thickness of 0.1 micron. Additionally the two stages may utilize different membrane materials. The feed and permeate pressures also are varied over ranges encompassing the values proposed by MTR.
The optimization space of membrane properties and operating conditions is scanned globally to determine the process design that minimizes LCOE. The oxygen concentration to the boiler is evaluated during the optimization process and can be used to constrain viable alternatives. The results indicate a fairly broad range of membrane properties can yield comparable LCOE near the minimum. The optimal operating pressure range is somewhat narrower. The minimum allowable oxygen concentration can constrain viable designs significantly and is critical to process economics.
See more of this Session: Poster Presentation III- Gas and Molecular Separation
See more of this Group/Topical: General Submissions
See more of this Group/Topical: General Submissions