A thermal and chemical fuel pretreatment process for NOx reduction from cement kiln

NOx emission has noticeably hindered cement industry from developing sustainably. A novel fuel pretreatment is developed to lower NOx emission. Besides, a pilot scale experimental facility was used to investigate differences between the fuel pretreatment and that of traditional low-nitrogen combustion with two different size ranges of coal (0–0.18 mm and 0.1–0.5 mm). The results shown that NOx emission attributed to fuel pretreatment is 40–45% lower than that of traditional low-nitrogen combustion with both size ranges of coal. Fuel pretreatment can maximally cut NOx emission as follows: partial fuel-N is reduced in situ to stable N2 at the preprocessing stage, thereby lowering the possibility of fuel-N oxidation in the precalciner; compared with parent coal, the reducing capacity of preprocessing product is enhanced for its larger specific surface area and lower graphitized degree in carbonaceous framework. Furthermore, particle size distribution could significantly influence above process. It is therefore revealed that the proposed approach more applies to NOx emission control in practical cement manufacture.