The Comparative study of Honghe lignite pyrolysis under the atmosphere of Methanol and Nitrogen

The pyrolysis of Honghe lignite was investigated on low heating rate (about 20 degrees C/min) conditions in a fixed bed reactor with 10g fed in. Nitrogen was used as carrier gas operating at the range from 50 to 200ml/min. And, the temperature was tested from 440 to 560 degrees C, the pressure ranges from 0.1MPa to 1.2MPa. The yields of coal tar, char, water and gas were obtained in experiments. The maximum coal tar yield of 9.77% (dry coal) was achieved at 520 degrees C, 50ml/in nitrogen flow rate, pressure 0.4MPa and 20 minutes holding time. Then methanol was injected in the system at the preheat temperature 240 degrees C(a little higher than its critical temperature). The methanol flow rate, pressure and holding time were also taken into consideration. And the results were compared with those obtained in pyrolysis under nitrogen atmosphere. It showed that higher liquid yield with lower yields of char, gas and loss were obtained with the presence of methanol, but the differences of char yields were slight. The total sulfur removal for methanol presence is considerably higher than the absence of methanol in pyrolysis. Considering the mild conditions of the pyrolysis with presence of methanol, this method may be an appropriate way to make use of the lignite efficiently and environmentally.