1. Introduction

Coal is a complicated solid fuel, containing C, H, O, N, S, etc. When the particle is heated, moisture, volatile and tars will be released and involved into multistep chemical reactions. The char after devolatilization also undergoes heterogeneous reaction. Generally, numerous elements, complicated structures and multiple stages of combustion are the main reasons for the complexity of coal combustion. The coal combustion process mainly includes devolatilization, ignition and char oxidation, also accompanying with metal release and partitioning behavior. The combustion efficiency and pollutant formation of coal combustion are interrelated with the above four processes. Therefore, in order to understand the coal combustion process, this thesis focuses on the above four aspects. Traditional experimental methods always change the combustion environment and the sudden change will cause target variation, collecting mirror and other problems. Therefore, in order to illustrate the detailed combustion process of pulverized coal particles and the dynamic behavior of metal precipitation process, this thesis aims to apply in situ optic diagnostic technology into the coal combustion research. Focusing on combustion and fine particulate matter formation, optic methods about molecule, radical, emission intensity, metal atom and surface temperature are mainly investigated.