Enhancing oxygen savings and carbon dioxide purity in biomass oxy-circulating fluidized bed combustion with an oxygen carrier
Seong‐Ju Kim, Ji Hong Moon, Sung-Ho Jo, Sung Jin Park, Jae Young Kim, Geon Uk Beak, Sang Hee Yoon, Ho-Jung Ryu, Ho Won, Sang Jun Yoon, Sung Min Yoon, Jae Goo Lee, Tae‐Young Mun
Abstract
A pure oxygen (O 2 ) supply for oxy-fuel combustion causes excessive power consumption and decreased net plant efficiency. The oxygen carrier-aided oxy-circulating fluidized-bed combustion (OCA-Oxy-CFBC) process can facilitate reduction in the O 2 supply requirement. Moreover, the use of an oxygen carrier, instead of silica sand, as bed materials may improve oxygen transport in the combustor, leading to a reduction in the pure O 2 supply required. This study aimed to investigate the effect of oxygen carrier addition on Oxy-CFBC characteristics, including temperature, pressure, solid suspension density, pollutant emissions, combustion efficiency, and O 2 reduction for stable operation. As an oxygen carrier, iron ore was introduced into the downcomer pipeline using a dedicated hopper during the biomass Oxy-CFBC process under low excess O 2 conditions. Although the O 2 concentration in the flue gas decreased by 1.7 vol%, the CO emissions decreased from 6.8 mg/MJ to 2.8 mg/MJ when the silica sand was replaced with 33 wt% iron ore. Furthermore, the CO 2 purity in the flue gas improved from 94.3 vol% to 95.7–97.4 vol% under a lower equivalence ratio (1.01–1.07) during stable OCA-Oxy-CFBC operation. Consequently, oxygen can be transported and supplied by adding an oxygen carrier during the biomass Oxy-CFBC operation, indicating O 2 savings of 4.86 % for the total amount of O 2 required.