Sulfur Removal And Optimal Operation In The CFB Boilers

According to two CFB boilers in the power plant of Sinopec Maoming Company, three factors, including different sulfur content of coal, Ca/S molar rate (1.8,2.3,2.8) and ash recirculation, were studied. The results showed that sulfur removal rate increased with the increasing of the coal sulfur content. When Ca/S molar rate changed, the variation trends of sulfur removal rate in different coal sulfur content would different. Cold ash recirculation was greatly good for increasing sulfur removal rate, decreasing Ca/S molar rate and lowing carbon content of ash. When the feeding valve of cold ash recirculation was about4rpm, Ca/S molar rate and carbon content of ash were reduced by0.74and8.31%, respectively. Meanwhile, according to the experimental data, optimization of removing sulfur was also analyzed. Different SO2emission limits with different coal sulfur content, corresponding dosage of CaCO3, quality of CaCO3(such as particle size and impurity) and coal blend were considered as the most important factors which had great impacts on sulfur removal rate. The results showed that there existed optimized range in the SO2emission control area. When SO2emission limits were lower than400mg/Nm3,200-250mg/Nm3would be the best range. Particle size of CaCI3influenced sulfur removal rate a lot. When they were smaller than0.1mm, limestone particles would run away easily with ash so that utilization of CaCO3decreased. Improving coal blend could enhance the stability of fuel in the furnace, lowing Ca/S molar rate and increasing utilization of CaCO3.Through the economical analysis, it was concluded that optimizing performances of equipments and improving economic indicators were the best way to realizing energy saving and emission reduction of pollutants.