Temperature rise characteristics of ZhunDong coal during microwave pyrolysis

A modified K-type thermocouple was used to study the temperature rise characteristics of ZhunDong raw coal and coal-absorber mixtures during microwave pyrolysis. The role of microwave absorber was discussed. The evolution of carbon crystallite structure in semi-char during pyrolysis was studied by means of X-ray diffraction. The relationship between the aromatic structure and the microwave absorption capability of semi-char was studied. The results showed that the assistant heating effect of absorber is only dominated in the initial devolatilization stage. Increasing the weight percentage of absorber can dramatically reduce the temperature rise time in the stage. In the intense devolatilization stage, the temperature rise rate of semi-char first increases dramatically and then decreases. The microwave absorption capability of semi-char is found to be controlled by the combined effects of the aromaticity and aromatic layer diameter. •The assistant heating effect of the microwave absorber is only dominated in the initial devolatilization stage.•The temperature rise rate of semi-char first increases dramatically and then decreases in the intense devolatilization stage.•The microwave absorption capability of semi-char is controlled by the aromaticity and aromatic layer diameter.