Investigation On Optimization Of Burner Arrangement Schemes And Formation Characteristics Of H₂S For A 600 MW Tangentially Fired Boiler

Corner tangentially fired boilers (C-TFBs) with pulverized-coal have been widely used in the power generation industry in China, accounting for more than 70% in the installed gross capacity. However, problems of slagging and high temperature corrosion are often detected in furnaces during operation due to the coal variations, coupled with inherent defects of furnace and the structure of burner. However, wall tangentially fired boilers (W-TFBs) have been paid close extensive attentions, where the pulverized coal flow is inflammable and combustion is stable. In addition, W-TFB can also effectively prevent slagging, high temperatures corrosion and overtemperature tube burst.In this work, a 600 MW C-TFB is selected as the benchmark, and retrofitted into different schemes of W-TFBs, with imaginary tangential circle diameters unchanged. A total of 13 schemes of TFBs are investigated, and the three-dimensional model of TFB is built and meshed. The performance of the boiler with different tangential arrangements of burners is numerically investigated by the commercially available software, Ansys Fluent. The simulation results of the C-TFB are compared with the design parameters and the accuracy of the simulation results is verified. The performance of the boiler with different burner arrangement schemes is analyzed based on the comprehensive considerations of the velocity fields, the temperature fields, the component concentration fields, the heat flux on furnace walls, the phenomena at the furnace outlet, the swirl numbers, the actual tangential circle diameters and the formation characteristics of H2S.The results show that, wall center tangentially fired scheme is concluded as the best tangential burner arrangement. The situation of flow jets inclined to impact the water-cooled wall dose not occure as the height increases. The average dimensionless tangential circle diameters can meet the design coal. The relatively low height of high-temperature region than other schemes is conducive to reducing carbon content of fly ash and reducing heat loss. At the height of bottom layer nozzle, the pulverized coal flow is more inflammable, and there is more satisfactory tangential circle, larger high-temperature combustion region. In addition, the risk of slagging can be reduced because of the richer oxygen atmosphere, and the concentration and generation areas of H2S near the water-cooled wall can also be effectively decreased, which could then lessen the possibility of high-temperature corrosion. The problem of the water-cooled walls’uneven heating can also be effectively solved and the risk of heat transfer deterioration can also be reduced. The residual swirling at furnace outlet is relatively not obvious, the gas velocity and temperature distributions are more symmetric, and can effectively prevent high-temperature burst of superheaters.This study on TFB burner arrangements provides important and meaningful reference for engineering. Based on comprehensive consideration of performance of the boiler with different tangential arrangements of burners, the wall center tangentially fired scheme is concluded as the best tangential burner arrangement among the arrangements studied in this work.