Innovative NOx reduction from cement kiln and pilot-scale experimental verification

Abstract

Nitrogen oxide emissions from cement industry have greatly promoted the formation of haze weather. Current denitration technologies can hardly meet the increasingly stringent emission requirements. Here we proposed an innovative method called “rear independent reduction” (RIR) to reduce nitrogen oxide emissions from the cement kiln. A pilot-scale experimental setup was put in place to verify its feasibility. Reduction efficiencies of 61.2% and 48.6% were obtained in the absence and presence of cement raw meal, respectively. The effects of amount of reduction pulverized coal, flue gas temperature, the addition of cement raw meal, and oxygen content in flue gas on the NOx reduction efficiency were comprehensively investigated. Increasing the amount of reduction pulverized coal cannot only enhance the reduction efficiency, but also promote the rise of flue gas temperature. The ideal flue gas temperature is around 900 °C. Oxygen content in flue gas determines the impact of cement raw meal on the reduction efficiency, and the optimal value is below 1.0%. The significant reduction of NOx in flue gas should be attributed to the reaction between reductants and nitrogen oxides. This work provides a new way to address the problem of NOx emission in cement industry.