Carbon Filter Process for Flue-Gas Carbon Capture on Carbonaceous Sorbents: Field Tests of Steam-Aided Vacuum Swing Adsorption

摘要

A carbon filter that selectively captures CO_2 from flue gas on porous carbonaceous sorbents is demonstrated in field tests, A new sorbent regeneration process, referred to as steam-aided vacuum swing adsorption (SA-VSA), uses steam under vacuum to displace CO_2 from the carbon. Steam aids vacuum by reducing the partial pressure of CO_2 without the need to reduce the total pressure to deep vacuum, which is a challenge for vacuum swing adsorption (VSA). In turn, vacuum prevents the bulk condensation of steam on the sorbent, which is a challenge for CO_2 recovery using direct steam. Over 100 sorption-desorption cycles on flue gas produced in the lab and at two coal-fired power plants demonstrate that the SA-VSA-equipped carbon filter process can produce a nearly pure CO_2 product (at least 98%) while achieving high recovery (at least 98%). While stable, flexible, and robust in achieving the very high recovery and purity targets, this technology offers ample room for improvement through process optimization and, especially, sorbent optimization. For one of the reasonable but arbitrarily selected and inexpensive sorbents, a preliminary cost estimate example suggests an energy penalty of 31%, which should be less or much less for better sorbents.