Assessment of Sulfur Oxides Emissions from Boilers Burning Bulgarian Lignite

Sulfur, which has a high content of Bulgarian lignite, undergoes complex transformations in its combustion process, changing the structure of its chemical compounds many times. The presence of sulfur components hampers the operation of combustion plants as they cause high and low-temperature corrosion and contribute to the formation of deposits on heating surfaces. The sulfur oxides produced at the boiler outlet are sulfur dioxide (SO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>) and sulfur trioxide (SO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>) with SO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> being the main oxide and SO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> resulting from additional reactions. The SOx emissions in the flue gases of boilers burning Bulgarian lignite were determined by two different approaches. One of them involves measurements in real conditions, while the other is computational and based on the elemental composition of the coal burned at the time of the measurements. The particularities of the sampling methods, apparatus and conditions, and the computational algorithm are described. The results of the measurements and calculations are presented.