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

Abstract

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.

Steam Regeneration of Polyethylenimine-Impregnated Silica Sorbent for Postcombustion CO2 Capture: A Multicyclic Study

“…In this case, a vacuum was pulled in the desorption stage, and as soon as it reached 30 Torr, steam was admitted to maintain this pressure. 27 CO 2 that was nearly 98% pure was recovered in a field test of 100 cycles. However, the sorbent used, coal-derived activated carbon, had a low CO 2 adsorption capacity and low CO 2 selectivity in the presence of moisture.…”

“…Based on their study, a hybrid approach of steam-aided vacuum-swing adsorption (SA-VSA) was proposed to alleviate the problems of condensation in steam stripping and a very low vacuum requirement in the VSA. In this case, a vacuum was pulled in the desorption stage, and as soon as it reached 30 Torr, steam was admitted to maintain this pressure . CO 2 that was nearly 98% pure was recovered in a field test of 100 cycles.…”

Facilely synthesized meso-macroporous polymer as support of poly(ethyleneimine) for highly efficient and selective capture of CO2

“…To obtain CO 2 with high purity, steam regeneration is required. Steam regeneration is a technology recently developed for the effective recycling of CO 2 adsorbents [57][58][59][60]. Steam with high temperature is a waste source of heat, and widely available in power plants.…”