Experimental and numerical analyses on ignition and burnout characteristic of low-rank lignite and semi-char blends

Abstract

The coal utilization and conversion in China are mainly consumed by combustion. In particular, co-firing of coal blends plays an important role in solving the urgent energy problems in China. In this work, the fundamental work on the combustion characteristics (ignition and burnout) of low-rank lignite and semi-char are conducted. TGA (thermal gravimetric analysis), WMR (wire mesh reactor), ODF (one-dimensional furnace), and Hencken flat flame burner are the main research techniques and also the method used in this work to study the two characteristics. The ignition is quite easy when the char fraction is between 15 and 40 %. The heterogeneous ignition becomes much easier when we increase the fraction of semi-char in the blends. The peak burnout value is of 10–30 % semi-char fraction. Results indicate that the blend coal characteristic ignition time is close to char in 1800 K and approaches low-rank coal ignition in 1500 and 1200 K, in accordance with the mechanism effect.