CO2 Capture from Simulated Syngas via Cyclic Carbonation/Calcination for a Naturally Occurring Limestone: Pilot-Plant Testing

Abstract

Experiments were performed using a dual fluidized bed reactor system, operated in a batch mode, in order to investigate the effects of steam and simulated syngas on CO{sub 2} capture and sorbent conversion efficiency for a naturally occurring Polish calcitic limestone. In addition, the effect of high partial pressures of CO{sub 2} on the calcination process was examined using either oxygen-enriched air or oxy-fuel combustion in the calciner. As expected, calcination under oxy-fuel conditions resulted in decreased carbonation conversion due primarily to particle sintering and pore pluggage. On average there was a decrease in carbonation conversion of approximately 36.5 and 33.4% for carbonation with steam and steam/simulated syngas, respectively, compared to similar experiments using oxygen-enriched air. However, during the carbonation of the limestone with steam present in the feed gas, it was observed that the high CO{sub 2} capture efficiency period was significantly extended compared to carbonation with only CO{sub 2} present. This resulted in increased CaO conversion from approximately 16.1 to 29.7% for the initial carbonation cycle. A further increase in carbonation conversion from 29.7 to 46.9%, was also observed when simulated syngas conditions (CO, H{sub 2}) were used in the carbonator. Analysis of the outlet gases also confirmedmore » that the calcined limestone catalyzes the water gas shift reaction, which we believe results in enhanced CO{sub 2} concentration levels at the grain surfaces of the sorbent.« less