Effect of reaction conditions on the agglomeration of the oxygen carrier in biomass chemical looping gasification

Abstract

The oxygen carrier (OC) agglomeration is an important factor limiting the development of biomass chemical looping gasification (CLG) technology. However, the agglomeration behavior of OC is not clear under multiple perspectives of reaction conditions. In this study, we investigated the Fe-based OC agglomeration behavior during CLG from three perspectives of biomass species, reaction temperature and steam/biomass (S/B). The results showed that biomass with high ash and K content was easy to form more low melting point substances, causing a lower deformation temperature (DT) and more severe agglomeration of OC after CLG. Moreover, with the increase of reaction temperature from 700 °C to 900 °C, the DT of OC decreased by 6.8 %, while the average particle size and agglomeration degree of OC increased by 26.2 % and 209.5 %, respectively. Although high temperature was beneficial for improving reaction performance and shortening reaction time, the excessive temperature would cause severe agglomeration and inhibit CLG process. In addition, the higher the S/B was, the more severe the agglomeration became. With the increase of S/B from 0 to 1.8, the DT of OC decreased by 3.2 %, while the average particle size and agglomeration degree of OC increased by 28.2 % and 75.5 %, respectively. The excessive S/B would form more KOH and NaOH with lower melting point, exacerbating the OC agglomeration and inhibiting the gasification.