The effect of additives on NO reduction using sewage sludge as a denitration agent for cement kiln flue gas

Experimental study on the effects of additives on the NO reduction efficiency by sludge combustion was carried out on a simulated cement precalciner, and the feasibility of sludge as a denitration agent for cement kiln flue gas was evaluated. The NO reduction efficiency by sludge combustion with and without cement raw meal are 53.75% and 59.03%, respectively. It indicates that cement raw meal(CRM) inhibit the NO reduction by sludge combustion, while its inhibitory effect is not obvious. Besides, the inhibitory effect of CRM on NO reduction can be further reduced by controlling the addition amount of Al2O3 and Fe2O3 in CRM. Meanwhile, when urea is added to the sludge, the NO reduction efficiency can reach 74.21% by sludge combustion, indicating that urea significantly promotes the NO reduction, which is attributed to the decomposition of urea to form NH3. Therefore, it is feasible to add sludge as a denitration agent in the cement precalciner to reduce NO in cement kiln flue gas.