EFFECTS OF EXCESS AIR AND COAL SULFUR CONTENT IN PERFORMANCE IMPROVEMENT OF 660 MW SUPERCRITICAL BOILERS IN TERMS OF ACID DEW POINT TEMPERATURE

Abstract

The objective of this study was to select an appropriate fuel having different sulfur contents in various coal fuels and optimize the excess air in order to reduce dry flue gas loss, avoid equipment damage due to sulfur dew point corrosion, and reduce maintenance and equipment installation costs. A tri-sector rotary air preheater was employed to exchange heat between dry flue gases and preheat the air (both primary and secondary air). The results showed that coal with 0.6165% sulfur (fuel 2) caused acid dew point temperatures (ADPTs) of 122.38°C and 124.947°C with 15% and 20% excess air, respectively, in a rotary air preheater set at a 30.5° angle, whereas coal with 1.627% sulfur (fuel 1) caused ADPTs of 131.299°C and 133.602°C with 15% and 20% excess air, respectively, in a rotary air preheater set at a 35.99° angle. The experimental results indicate that the use of fuel 2 coal consumption can reduce carbon dioxide (CO₂) emission by nearly 4 metric tons (MT)/hour, which is equivalent to a reduction of CO₂ emission of 3.8 MT/hour.