Characterizations of the coal char using slag as heat carrier in allothermal pyrolysis process

Abstract

ABSTRACT In this work, the direction of allothermal coal pyrolysis reaction was driven by the waste heat of blast furnace slag. The structure features of the coal char mixed with/without slag was characterized by BET and SEM. The experiments of thermogravimetric analyzer were conducted to obtain the coal pyrolysis characteristics. The kinetic parameters of coal pyrolysis reaction were extracted using the reaction model based on the Arrhenius law and Li Chung-Hsiung method. The BET and SEM results showed that the slag addition could improve the structure features of the coal char effectively. The specific surface area, pore volume & size increased significantly. With the slag addition, characteristic temperatures of pyrolysis reaction did not change obviously. Peak temperature and final temperature increased by approximate 3.38 K and 5.55 K, respectively. However, the maximum weight reduce and pyrolysis characteristic index were enhanced dramatically. A single three-order reaction model was used to deduce the coal pyrolysis reaction successfully. The activation energy of the coal pyrolysis reaction decreased from 116.31 kJ·mol−1 to 90.67 kJ·mol−1, and the pre-exponential factor decreased from 6606.19 min−1 to 2457.91 min−1. Overall, slag provided the heat for the pyrolysis reaction and acted as the catalyst.