(600au) Sulfur Trioxide Formation during Oxy-Coal Combustion

Increasing demand of energy, due to the ever-growing world population, has ensured coal to be the primary source of electricity generation for many years to come. With a recorded level of 398.03 ppm of CO₂ in the atmosphere, 38% of which can be attributed to power generation sector, US holds the second place in world for CO₂ emissions. Oxy-coal combustion technology is a promising solution for implementing carbon capture and storage (CCS) successfully. Removal of N₂ from the oxidizer lessens the volume of flue gas to be processed; which consists mostly of CO₂. This CO₂ laden flue gas can be easily sequestered, with a CO₂ removal efficiency of 90%~95%. Several power generation plants, based on oxy-coal combustion, are being successfully operated in Australia and Europe. FutureGen 2.0, a joint venture of DOE, Air Liquide and B&W, is expected to be running commercially by 2023.  

Reduced flue gas volume causes increase in the concentrations of corrosive species. Increased SO₃ concentration has been reported by different case studies resulting from changed combustion environment. SO₃ is a major concern for power plants as it can cause both high temperature corrosion in boilers and severe low temperature corrosion in flue gas ducts and economizers. Before retrofitting any existing plant for this technology, it is crucial to perform an elaborate study reporting SO₃ concentration under the conditions analogous to an actual power plant.

In this study, SO₃ formation trends in oxy-coal combustion under different operating conditions will be explored. To serve this purpose, an experimental setup was built consisting of a burner followed; a reactor; subjected to temperature profile reflecting actual operating conditions. Samples can be obtained from the reactor at every 5cm interval simultaneously without interrupting the continuity of the experiment. FTIR, coupled with a variable path length cell, is applied for measurement of SO₃ in gaseous phase. From the experiments performed, a clear picture of SO₃ concentration profile along the varying process conditions will be obtained and this data can be used to develop and validate a kinetic model that can predict the concentrations of SO_x species in the flue gas.