Characteristics of microalgae gasification through chemical looping in the presence of steam

Abstract

As a novel gasification technology, chemical looping gasification (CLG) was considered as a promising technology in solid fuel gasification. In this work, CLG was applied into microalgae, and the characteristics of syngas production and oxygen carrier in the presence of steam were obtained through experiments in a fixed bed reactor. The results showed that the partial oxidation of oxygen carrier improved the gasification efficiency from 61.65% to 81.64%, with the combustible gas yield of 1.05 Nm3/kg, and this promotion effect mainly occurred at char gasification stage. Also, an optimal Fe2O3/C molar ratio of 0.25 was determined for the maximum gasification efficiency. 800 °C was needed for the gasification efficiency over 70%, but excess temperature caused the formation of dense layer on oxygen carrier particle surface. Steam as gasification agent promoted syngas production, but excess steam decreased the gasification efficiency. Steam also enhanced the hydrogen production by the conversion of Fe/FeO into Fe3O4, avoiding the intensive reduction of oxygen carrier. The Fe2O3 oxygen carrier maintained a good reactivity in 10th cycle while used for microalgae CLG. The results indicated that CLG provided a potential route for producing combustible gas from microalgae.