Pyrolysis of Hailar lignite in an autogenerated steam agent

Abstract

An in situ pyrolysis process of high moisture content lignite in an autogenerated steam agent was proposed. The aim is to utilize steam autogenerated from lignite moisture as a reactant to produce fuel gas and additional hydrogen. Thermogravimetric analysis revealed that mass loss and maximum mass loss rate increased with the rise of heating rates. The in situ pyrolysis process was performed in a screw kiln reactor to investigate the effects of moisture content and reactor temperature on product yields, gas compositions, and pyrolysis performance. The results demonstrated that inherent moisture in lignite had a significant influence on the product yield. The pyrolysis of L R (raw lignite with a moisture content of 36.9 %, wet basis) at 900 °C exhibited higher dry yield of 33.67 mL g−1 and H2 content of 50.3 vol% than those from the pyrolysis of the predried lignite. It was also shown that increasing reaction temperature led to a rising dry gas yield and H2 yield. The pyrolysis of L R showed the maximum dry yield of 33.7 mL g−1 and H2 content of 53.2 vol% at 1,000 °C. The LHV of fuel gas ranged from 18.45 to 14.38 MJ Nm−3 when the reactor temperature increased from 600 to 1,000 °C.