Thermal and kinetic behaviors of pyrolytic carbon black and gas coal in co-combustion

Abstract

In this study, a combustion study of tire pyrolytic carbon black (CBp), gas coal (GC), and their blends was carried out by thermogravimetric analysis with four heating rates under air atmosphere. And the structure characteristics of CBp and GC were studied using particle size distribution, scanning electron microscope, X-ray diffraction, Raman spectra followed by peak deconvolution and data analysis. The results demonstrated that the structural differences between CBp and GC directly affected their thermal behavior trends. GC with low graphitization degree had more combustibility reactivity than that of CBp, while the mean reaction rate and maximum reaction rate of CBp were larger than GC due to its bigger specific surface area and higher porosity. For blends, the combustibility reactivity could be improved by blending with GC, and there was obviously synergetic effect for the co-combustion of CBp and GC. The combustion reaction mechanisms and kinetic parameters were carried out using three non-isothermal kinetic models: random nucleation nuclei growth model (RNGM), volume reaction model, and unreacted core model. The kinetic analysis demonstrated that the RNGM model had a better performance than other models for describing the thermal behavior of the selected samples. In addition, the synergetic effect between CBp and GC was observed from the kinetics data calculated by RNGM. The activation energies of CBp and GC calculated by RNGM model were 119.6 kJ mol−1 and 126.4 kJ mol−1, respectively, whereas the lowest activation energy for their blends was 104.3 kJ mol−1 when CBp ratio was 40%.