FLASH PYROLYSIS OF COAL-METHANOL SLURRY

We have recently developed two types of pyrolysis methods. One is flash pyrolysis of coal preswollen with a hydrogen donor solvent in an inert atmosphere (method I). This method increased significantly the yields of total volatiles and tar. The other is the pyrolysis of coal in an atmosphere containing a solvent vapor (method II). This method controlled the secondary gas phase reactions to increase the yields of benzene, toluene and xylene (BTX) selectively. In this paper, flash pyrolysis of coal-solvent slurry was proposed as a means to realize the two methods in practical processes. A coal-methanol mixture prepared from an Australian brown coal (Morwell) was pyrolyzed in a free fall pyrolyzer at 923-1123K. This method realized significant increases in the yields of total volatiles, tar and BTX. At 1023K, the yields of tar and BTX reached surprisingly high levels of 23.3 and 7.8kg/100kg-coal, respectively. Addition of a hydrogen donor solvent to the coal-methanol slurry realized further increases in the yields of total volatiles and tar. Addition of water to the slurry was also examined to utlize the coal-water slurry in this pyrolysis method.