Effect of Bone During Fixed bed Pyrolysis of Biomass

Abstract

Bio-char from biomass pyrolysis offers a geotechnical solution to the major global issues of climate change, soil degradation and food shortage. The focus of this study is to generate stable and nitrogen enriched bio-char and high quality oils produced from co-pyrolysis of biomass with bone at low temperatures. The char can act as fertiliser while at the same time optimises the chemical stability of the char to act as a Carbon Capture and Storage system (CCS). By improving the use of bio-char, it may be possible to also utilise the bio-oil for renewable generation. To achieve this, the present study has focused on the influence of bone (BM) addition from 0wt% to 25wt% during pyrolysis of Pistachio (PS), Wood (WD), and wheat straw (ST) in a fixed bed pyrolysis reactor at 3000C. The analysis of the char products shows that the addition of bone to the biomass increased their char yields from 0wt% to 10wt%, but higher addition of bone was found to reduced the overall char yield from the biomass. At 10wt% bone addition, the carbon, hydrogen, and nitrogen content, and the gross calorific value of the chars were increased by 7wt%, 29wt%, 163wt% and 19Mj/kg, for wheat straw, 62wt%, 46wt%, 135wt%, 110Mj/kg for wood and 7wt%, 76wt%, 42wt% and 33Mj/kg for pistachio. The oxygen content of the wheat straw, pistachio and wood mixed with 10wt% bone decreased by 28wt%, 21wt%, and 93wt%, respectively. The bio-oil yield increased for the bone addition up to 5%wt% for all the samples. Gas production was minimized at 10wt%. Especially, the addition of bone to PS alters the concentration of important chemicals in the bio-oil generated while the kinetic study shows that bone addition alters the reaction rate for the conversion of the biomass to products. The major hydrocarbons components of the gas produced from pistachio were of C1 to C4 with CH4 constituting up to 42wt% of the total evolved gas. Comparison between the elemental components of the chars produced showed similar pattern of change for all the biomass investigated. Hence it can be concluded that at 10wt% addition of bone to the biomass, bio-chars and oil yield could be optimised for soil amendment, energy production, while retaining carbon for sequestration.