Dewatering/drying of Victorian brown coal will be an integral part of future brown coal utilization processes aimed at the reduction of greenhouse gas emissions. This study aims to investigate the effects of the thermal pretreatment of brown coal in the presence of steam/water on its subsequent pyrolysis behavior. Victorian (Loy Yang) brown coal was thermally pretreated in pressurized steam and inert atmospheres. The pyrolysis behavior of these pretreated coal samples was investigated in a wire-mesh reactor. While the pretreatment in steam at temperatures higher than 250 °C increased the char yield of the steam-treated coal, it did not affect the overall pyrolysis char yield at 1000 °C s-1 if the weight loss during the pretreatment in steam was also considered. However, the tar yield decreased significantly after the pretreatment in the presence of steam. The UV-fluorescence spectroscopy of tars revealed that the release of large aromatic systems from the steam-treated coal was only affected by the pretreatment in steam if the treatment temperature was very high (e.g. 350 °C. The loss of NaCl and the use of high pressure during the pretreatment of brown coal in steam were not the main reasons for the changes in the observed tar yield. The hydrolysis of O-containing structures such as ethers, esters, and carboxylates during the pretreatment in the presence of steam plays an important role in the fates of these O-containing structures during pretreatment and subsequent pyrolysis, leading to changes in the pyrolysis behavior of the brown coal.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Fuel Technology
- Energy Engineering and Power Technology