Adhesion of Fluidized Bed Particles on Biomass Char in Fluidized Bed Rapid Pyrolysis

Abstract

Rapid pyrolysis experiments using a fluidized bed reactor, FBR, were carried out for various biomass species. Alumina particles used as bed particles adhered on the surface of the produced char. This phenomenon may cause serious operational problems of FBR such as agglomeration, clogging and so on. The effects of various conditions including heating rate and pyrolysis temperature, together with type of biomass were observed on the adhesion behavior of the bed particles. Among the samples of Japanese cypress, Eucalyptus camaldulensis, bagasse, and switchgrass, while all samples showed the phenomenon in case of rapid pyrolysis, no adhesion was observed in case of slow (10°C/min) pyrolysis, excepting that switchgrass showed the phenomenon at 400-1000°C (mainly 300-600°C). By rapid pyrolysis, softwood samples showed the adhesion phenomenon between 600 and 1200°C and hardwood, between 800 and 1000°C. Much more particles adhered on softwood char than on hardwood char. Among the herbaceous plant and agricultural residue samples, the adherability and temperature range strongly depended on the species. To investigate the effects of biomass type on the adhesion phenomenon, biomass model materials were pyrolyzed. Adhesion behavior was not observed for lignin only, however, it was observed with cellulose or hemicellulose and was also affected by their kind.