Thermal Coal

Thermal Coal Thermal coal is a type of bituminous coal which is used to provide heat energy in combustion in various types of furnaces via the pulverized fuel method because of its high calorific value (CV). It is also sometimes called as non-coking coal, steam coal, or boiler coal. It includes all those bituminous coals which are not included under coking coal category. It is characterized by higher volatile matter (VM) than anthracite (more than 10 %) and lower carbon (C) content (less than 90 % fixed C). Its gross CV is greater than 5700 kcal/kg on an ash?free but moist basis. The greatest use of thermal coal is for the generation of steam in the boilers for the purpose of generation of electricity. Thermal coal is also used in some of the processes for ironmaking especially in the production of direct reduced iron (DRI) and in the smelting reduction processes for the production of hot metal (HM). Thermal coal is a complex heterogeneous substance. Hence, it has no fixed chemical formula. Its characteristics and hence its CV vary widely. Thermal coals like other coals also contain carbon (C), oxygen (O2), and hydrogen (H2). The other constituents in thermal coals include sulphur (S), nitrogen (N2), ash, chlorine (Cl), and sodium (Na). The quality of thermal of coals is based on the amount of C, O2, and H2 present in coal. The metallic elements in the thermal coal contribute to the coal ash. The chemical structure of the organic molecules of the thermal coal is very complex and is dependent on the rank of the coal. It varies from one coal to another coal. Typical structure of thermal coal is given in Fig 1. Fig 1 Typical structure of thermal coal The performance of the...