Effects of Metallic Heating Plates on Coal Pyrolysis Behavior in a Fixed-Bed Reactor Enhanced with Internals

A newly configured fixed-bed reactor with internals has been proposed to enhance the coal pyrolysis performance. In this study, the effects of metallic plates on coal pyrolysis behavior were investigated in this reactor. The results show that the increased quantity of the metallic plates enhanced the heat transfer and shortened the residence time of volatiles within the coal particles. In addition, the pressure drop results suggest that the increased quantity of plates caused short circuiting of gas and raised the particle interstices, which reduced the gas diffusion resistance of pyrolysis products. Therefore, more gaseous pyrolysis products flowed into central low-temperature coal bed and escaped from the gas collection pipe, suppressing the secondary reaction of pyrolysis products and increasing the tar yield and quality. At a furnace temperature of 900 degrees C, the increase in metallic plates from 0 to 8 raised the tar yield and light tar fraction from 5.20 and 69.5 wt % to 7.86 and 77.0 wt %, respectively. Meanwhile, the <= C-14 hydrocarbons were elevated from 42.11 to 50.44 wt %, but the >= C-20 hydrocarbons were lowered from 29.95 to 19.74 wt %. However, an excessive increase in plates raised the heating rate of coal, cracking more pyrolysis products and decreasing the tar yield and quality.