Abstract
The paper considers the influence of technological factors (design of the boiler-unit, load, air excess, the number of working dust collecting systems) on the formation and reduction of sulfur dioxide emissions in boilers with liquid slag removal. Understanding of this influence can be used both at many operating heat and power sources, and in the development of new combustion technologies. The long-term experience of burning brown coals of the Kansk-Achinsk basin (KAC) at CHPP-6 in Bratsk in boilers of the BKZ-320-140 PT type is studied and analyzed. The analysis uses the results of various thermodynamic and industrial studies of the sulfur dioxide formation during the combustion of KAC, including those carried out by the authors. They identified the temperature and structural zones of the boiler unit, where the resulting reaction of the sulfur dioxide transition to calcium sulfate occurs. It was found that such a zone is the upper part of the cooling chamber, where the indicated transition occurs at temperatures of 1500 ÷ 1400 K. It was found that SO2 emissions rise with an increase in the boiler load and air excess. They also depend on the number of dust systems and their combination (determining the turbulization of combustion processes). A technological mechanism for the sulfur dioxide transition to calcium sulfate for the operation of boilers with liquid slag removal is proposed. Regime and constructive measures are proposed to reduce emissions of sulfur dioxide.
Highlights
The identification and clarification of factors increasing the efficiency of boilers with liquid slag removal can be in demand both at many operating TPPs and in the development of new combustion technologies
When analyzing the experimental data, the authors of this paper employed the results of the thermodynamic calculations of the Kansk-Achinsk coals (KAC) combustion carried out at the Siberian Power Engineering Institute (SEI, ISEM) [3,4], including by the author [5]
At α> 1, the highest sulfur oxides SO2 and SO3 prevail. Both domestic [7,8] and foreign researchers believe that the oxidation of sulfur dioxide to sulfuric anhydride is 0.2-2.5% for boiler units
Summary
The identification and clarification of factors increasing the efficiency of boilers with liquid slag removal can be in demand both at many operating TPPs and in the development of new combustion technologies. The above experience includes successful upgrades of combustion technologies of the KAU IrshaBorodinskoye field, as a result of which emissions of nitrogen oxides (NOx) were significantly reduced [1], as well as experimental studies, during which the concentrations of NOx, sulfur dioxide (SO2), benzo [a] pyrene (BaP) were measured at various points of the boiler , and other technical and economic parameters [1,2]. Note that for the KAC Irsha-Borodinsky deposit, the molar ratio of calcium to sulfur (Ca/S) is approximately equal to three Until recently, this reaction has practically not been studied in relation to the combustion of KAC. The results obtained are important because such combustion conditions are suitable for fluidized bed boilers, and for some solid fuel flaring technologies, which will be discussed below. The aim of this paper is to analyze the environmental characteristics of the combustion processes of KAU and identify technical solutions to reduce emissions of all major pollutants, including SO2
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