Characteristics And Mechanisms Study On Co-pelletization Of Torrefied Biomass And Oil Cake

Biomass has become a sustainable and environmental energy resou rce as its attractive characteristics, such as huge quantity, renewable, none net CO 2 emission and low production cost. In general, pelletization of biomass makes its density 4 to10 times higher than before which can significantly reduce the transportation /storage costs. However, high moisture absorption, low energy density and rapid combustion reactivity of biomass restrict the large-scale application of biomass pellets. Therefore, the advancement of the properties of biomass pellet has gained widespread attention. Among the technologies to advance the properties of biomass, torrefaction was regarded as an efficient and feasible method. Pretreatment of torrefaction is a pyrolytic process at 200-300 oC in an inert atmosphere. In this study, two kinds of biomass(cedarwood and camphorwood) were pretreated at different torrefaction temperature(240 oC, 270 oC, 300 oC). Caster bean cake, one kind of high-production oil cakes in East Asia, was selected as the additive. The torrefied biomass materials were blended with caster bean cake for co-pelletization. Subsequently, the effects of the degree of torrefaction and caster bean cake ratio on the energy consumption during pelletization and pellet properties were investigated. The primary objectives of this study were to illuminate the mechanisms of the synergism between torrefaction and co-pelletization. This study is divided into the following three aspects :(1)The blending of biomass with oil cake would increase the density of pellets, and thus reduce their costs during production, transport and storage. The energy consumption of compaction decreased with the increasing content of castor bean cake, while the energy consumption of extrusion and pellets’ energy density had an opposite tendency. Moreover, the maximum compression force and hardness increased with the blend ratio of CAS(castor bean cake) rising. This thermal analysis suggests that adding CAS can enhance char combustion and lead to more reactivi ty during char combustion. 10-20% of castor bean cake would be a suitable proportion in the co-pelletization with biomass in terms of energy consumption and pellet properties.(2)Synergism of torrefaction and co-pelletization was investigated. In this study, biomass were torrified at 240 oC, 270 oC and 300 oC.Torrefaction improved the characteristics of pellets, with higher HHV, lower moisture absorption and better combustion characteristic. Meanwhile, co-pelletization between torrefied biomass and cater bean cake can reduce several negative effects of torrefaction such as higher energy consumption, lower pellet density and strength. The present study indicated that synergism performances of the torrefaction and co-pelletization with CAS provide a promising alternative for fuel production from biomass and oil cake. The optimal conditions for energy consumption and pellet strength were torrefied at 270 oC and a blending with 15% CAS for both biomass materials.