Characteristic Comparison of CCh-assisted Co-gasification and Co-pyrolysis using Waste Tire and Pine Bark Mixtures

摘要

Thermochemical conversion of waste tire combined with forestry waste (mixture waste) into alternative fuels such as syngas can help provide energy security, solutions for growing waste tire management, climate change mitigation and environmental protection. In this paper, co-gasification and co-pyrolysis of waste tire and pine bark with a focus on syngas is reported at defined waste tire (WT) and pine bark (PB) blend fractions of WT:PB = 0:1, 1:0. 1:1, 1:3, and 3:1. The thermal decomposition behavior during co-gasification of blends in the surrounding CO_2 atmosphere and co-pyrolysis under N_2 atmosphere for the specific blends were investigated at 900 °C using a lab-scale semi-batch fixed-bed reactor test facility. Gasification and pyrolysis behaviors were investigated in terms of evolved flow rate of CO, H_2. total hydrocarbons (C_mH_n). and total syngas yield at the different blend ratios of WT and PB. Gas yield, char yield, gas yield efficiency and energy recovered in gasification and pyrolysis were also calculated and compared. Synergistic effects in the syngas yield and the role of waste tire and pine bark were analyzed. The observed synergy was quantified by a direct comparison of the results on experimental yields from WT-PB blends as compared to the correspondingly calculated aggregate results from the gasification and pyrolysis of separate feedstock components. Results showed that increase in pine bark ratio increased flow-rate peak of H_2, CO, total syngas, but decreased flow rate peak of C-mH_n for both gasification and pyrolysis. The yields of CO and total syngas of gasification were bigger than that of pyrolysis at the same blend ratio, however, the yield of char, H_2 and C_mH_n from gasification were smaller than that of pyrolysis. Gas yield efficiency of pyrolysis enhanced using blends, while no obvious influence was found in gasification. Co-gasification of waste tire and pine bark slightly enhanced energy recovery efficiency for waste-tire content of 75% and reduced at other compositional ratios. Co-pyrolysis of waste tire and pine bark significantly enhanced energy recovery efficiency. The results provide practical insights on energy recovery and waste treatment for both waste tire and forestry waste using thermochemical conversion.