The main drawback encountered when using the conventional firing methods with pulverized coal, of either a direct or indirect type, is found in the requirement to dry the fuel in order to make the moisture therein be around 1%, and thus insure the product fluidity. Moreover it does also appear as necessary with such known methods, to perform the intermediate conveying and storage steps for the dried pulverized coal under nitrogen atmosphere to limit the explosion dangers. Finally the combustion products or vapours in the conventional methods and equipments, are directly discharged to the atmosphere, without any filtering, which is highly nefarious to the environment.