Using sewage sludge as a flue gas denitration agent for the cement industry: Factor assessment and feasibility

Abstract In this study, the feasibility of using sludge as a flue gas denitration agent for the cement industry was evaluated, and factors affecting NO X (NO + NO 2 ) removal were systematically investigated using a custom-built laboratory-scale fluid-bed reactor. The results indicate that sludge is an effective NO X reducing agent, and sludge dosage, combustion temperature, and O 2 concentration greatly affect NO X removal. Finally, the optimal operation conditions for the sludge denitration process were determined. With a sludge dosage of 0.75 g/min, sludge particle size of 60–80 mesh, combustion temperature of 900 °C, gas flow rate of 18 L/min, O 2 concentration of 3% (v/v), and the CO 2 concentration of 25% (v/v), the maximum NO X removal efficiency could reach 74.16 ± 4.65%. Moreover, preliminary research on the mechanism showed the occurrence of homogeneous and heterogeneous NO X reductions during the sludge denitration process. The homogeneous NO X reduction considerably contributes to NO X removal. Therefore, the use of sewage sludge as a flue gas denitration agent for the cement industry is feasible.