Co-pyrolysis kinetics and pyrolysis product distribution of various tannery wastes

Abstract

Tanning sludge, chrome tanned buffing dust and chrome shavings were selected as experimental materials. The non-isothermal distributed activation energy model (DAEM) was used to study the pyrolysis kinetic parameters. Effects of particle size and temperature on distribution of co-pyrolysis products of various tanning wastes were investigated in a fixed-bed pyrolysis reactor, which provided a new approach for comprehensive thermal treatment of various tannery wastes. The results show that the total activation energy required for the co-pyrolysis decreases and then increases in the range of conversion rate of 0.1 to 0.8. The tar yield decreases with raising particle size, while the yields of gas and char increase. With increasing pyrolysis temperature, the tar yield increases rapidly to a peak value of 17% at 600°C, and then decreases, correspondingly the char yield decreases while the gas yield increases. At 600°C and the particle size of 1.6–2.5 mm, specific surface area of the char is larger, and the light fractions in tar is higher. Thus, co-pyrolysis is conducive to clean treatment of the tannery wastes.