Simultaneous Pyrolysis of Coal and Biomass in a Drop-Tube–Fixed-Bed Reactor

[Image: see text] Copyrolysis of coal and biomass has been extensively studied to exploit its inherent synergistic effects; however, the different pyrolysis temperature zones of coal and biomass seriously affect the realization of these effects. Therefore, a new copyrolysis method (preheating the coal to a certain temperature and then adding the biomass in a drop-tube–fixed-bed reactor, denoted as M1) was designed herein to achieve “simultaneous” pyrolysis of coal and biomass. The yields of products and the characteristics of M1-produced tar were estimated and compared with those of tar obtained by fixed-bed-reactor (denoted as M2)-based copyrolysis. M1 achieved a higher tar yield and lower water content than M2. The M1-generated tar exhibited a lower free-radical concentration, higher H/C ratio, higher levels of uncondensed aromatic hydrogen, and shorter side-chains than that produced by M2. The temperature of HLBE coal at which the WSs were fed to the reactor in M1, denoted as T(F), affects the “simultaneous” pyrolysis. T(F) values of 300, 400, and 500 °C were studied, and it was found that the tar yield obtained at a T(F) of 400 °C (the main pyrolysis temperature of coal) is the highest, the water yield is the lowest, and the free-radical concentration of the tar is also the lowest among the investigated samples.