INCOMPLETE COAL COMBUSTION AND FACTORS THAT INFLUENCE THE CONTENT OF UNBURNED CARBON IN BOTTOM ASH. EFFECTS OF INCOMPLETE COMBUSTION ON THE OPERATION OF THE WET FGD SYSTEM - A CASE STUDY

Abstract

Sulphur oxide removal from flue gas is a legal requirement for any large capacity combustion equipment. The paper presents the case of thermal power plant Rovinari (Romania), where Wet Flue Gas Desulfurization with limestone slurry has been implemented in order to reduce the SO2 concentration from 4000 mg/m3 to 400 mg/m3 (legal limit). The operation and sulfur oxides removal performance of the desulfurization system depend on a set of given design parameters value, which, in practice, cannot be fully controlled. One such factor is the quality of the coal, which is a parameter with high and random variability. Improper processing of the coal before being delivered to the burners causes incomplete combustion, which results in loss of combustible mass. Incomplete combustion means that some coal particles do not burn at all (100% loss) while others undergo a partial combustion but fall into the bottom ash collecting and transport system before complete combustion can take place. The objective of the paper is to present the specific factors occurring at Rovinari thermal power plant and analyse quantitatively and qualitatively the performance of the desulfurization system under incomplete coal combustion conditions.

Keywords

• power plant system
• bottom ash
• sulfur oxides
• incomplete combustion
• unburned carbon