Pyrolysis characteristics of Hailar lignite by thermal analysis technique

Based on the self-proposed integrated process for direct drying and pyrolysis (IPDDP) of carbon-based materials with high water content, the pyrolysis reaction in a nitrogen atmosphere and combustion performance in an air atmosphere of Hailar lignite was measured using thermobalance. The effects of the heating rate on pyrolysis characteristics of lignite were investigated. Also, the feasibility of this IPDDP was discussed. The results showed that lignite was dehydrated below 110°C in a nitrogen atmosphere with a weight loss about 11%. In the temperature range between 110°C and 690°C, the volatiles were removed and the pyrolysis took place, with a weight loss about 23%. Thereafter, the char from pyrolysis was transfered into carbon, with a weight loss about 10%, during the temperature up to 900°C. While in an air atmosphere, lignite as well as the volatiles burned between the narrow temperature range of 315°C to 320°C. It provided a residual of about 13.7% ash. Water desorption will be postponed at higher heating rate. This enabled the co-pyrolysis of water vapor, volatiles and the char from pyrolysis. It proves the feasibility of the IPDDP, to some extent.