Pyrolysis of a Victorian Brown Coal in Helium and CO2 Atmosphere

Pyrolysis of a Victorian brown coal was performed in helium and CO2 atmosphere under atmospheric flow in a wire-mesh reactor. Experiments were carried out over the ranges of pyrolysis conditions: heating rate of 0.5–1000 oC s-1, holding temperature of 500–900 °C, and holding time at peak temperature of 0 to 60 s. The experimental results revealed that the tar yield increased with the increase of heating rate in both helium and CO2, however negligible effect of gas atmosphere on the tar yield was observed. The char yield was not very sensitive to changes in heating rate at temperature lower than 800 oC in both helium and CO2. At higher temperatures, the gasification of nascent char by CO2 led to significant decreases in the char yields. Decreasing heating rate from 1000 to 0.5 oC s-1 led to more reduction in reactivity for the char from the Ca-form coal than for the char from the Na-form coal