Effect of the Moisture Content in Coal on the Pyrolysis Behavior in an Indirectly Heated Fixed-Bed Reactor with Internals

The fixed-bed reactor with internals has been proposed to enhance the pyrolysis performance for coal. In this study, the pyrolysis behavior of different coal moisture contents and the reaction mechanism were investigated in an indirectly heated fixed-bed reactor with internals. The results showed that, at a furnace temperature of 900 °C, the increased coal moisture content went from 0.41 to 11.68 wt % and significantly modified the temperature fields, thereby prolonging the pyrolysis time to reach 500 °C and then enhancing the condensation and trapping of the coal at the bed center. Therefore, the tar yield and light tar content were raised from 9.21 and 63.7 wt % to 10.74 and 64.5 wt %, respectively. However, when the coal moisture content exceeded 16.77 wt %, the tar yield and light tar content decreased to 8.55 and 62.0 wt %, respectively. In addition, the higher heating value (HHV) of char with internals was dramatically higher than that without internals, and the char HHV in the reactor with internals rose primarily and then decreased with the increase in the coal moisture; meanwhile, its fixed carbon content of char showed an increase, followed by a decline. In contrast, the pyrolysis products varied slightly in the reactor without internals.