Thermal behavior and kinetic study on the pyrolysis of lean coal blends with thermally dissolved coal

In this paper, we use organic solvent N-methyl pyrrolidone (NMP) to thermally dissolve Kelan (KL) coal. The final product is thermally dissolved coal (TDC). The thermal behavior and non-isothermal kinetics of Guandi (GD) coal and TDC, as well as the co-pyrolysis of coal blends, have been studied by three methods (Friedman method (FR), Flynn–Wall–Ozawa method (FWO) and distributed activation energy model (DAEM)). Obtained results show that TDC has a higher maximum devolatilization rate and lower temperature corresponding to the starting and maximum rates of pyrolysis, compared to GD coal. The addition of TDC not only improves the maximum devolatilization rate of coal blends, but also reduces the temperature corresponding to the maximum devolatilization rate. Obtained results indicate that synergistic reactions may occur between the temperatures corresponding to the maximum devolatilization rates of GD and TDC. In this study, the apparent activation energy E obtained by FR, FWO and DAEM methods of coal blends with various addition of TDC almost increased with increasing conversion. There is a kinetic compensation effect in the kinetic process of coal pyrolysis and the reaction kinetics compensation effect equation.