Co-pyrolysis characteristics of camellia oleifera shell and coal in a TGA and a fixed-bed reactor

Abstract

The pyrolysis characteristics of camellia oleifera shell (COS), coal and their mixture were investigated using a thermogravimetric analyzer (TGA) and fixed-bed reactor. The decomposition reactions and kinetic analyses of COS, coal and their mixture from using TGA were compared. The results showed that during the pyrolysis process of COS and coal lonely, heat transfer hysteresis would occur with the increase of heating rates, and the synergistic effects during the co-pyrolysis of COS and coal could be enhanced by increasing the proportion of COS. In addition, from the results of kinetic analyses, in the range of 666∼750 °C, the activation energy (Ea) was gradually decreased with the increase of COS content, which was from about 59.7 kJ/mol to 12.7 kJ/mol. The effects of mixing ratio of COS to coal, pyrolysis temperature and heating rate on the pyrolysis process were further evaluated by using the fixed-bed reactor, and the optimal operating conditions were found (60% COS mixing ratio, 600 °C, and 10 °C/min) to obtain a higher yield of liquid around 30% and modifying the product composition. Gas products containing hydrogen, carbon-monoxide, carbon-dioxide and hydrocarbons were analyzed by gas chromatography (GC). Interestingly, the tar produced by co-pyrolysis of the blends was mainly composed of small molecule such as phenols, and there were basically no polycyclic aromatic hydrocarbons. For the fixed-bed reactor, the synergistic effects mainly impacted on the product composition, rather than the % distribution of the products.