Effect of mineral matter on NO reduction in coal reburning process

The effect of mineral matter on the NO reduction efficiency during the coal reburning process was studied in an entrained flow reactor. Apart from the homogeneous reactions between hydrocarbon radicals and NO, the heterogeneous reaction between NO and char is also important in the coal reburning process. The discrepancy in NO reduction between two kinds of bituminous coals with similar volatile matter and inherent nitrogen contents was investigated. Shenhua coal enriched with Na, K, Ca, and Fe in ash has more than a 15% predominance over the Huainan coal. The mineral matters in the coal ash were studied by the demineralization and reimpregnation process. The original coal, demineralized coal, and impregnated coal were evaluated as reburning fuels. Results show that the mineral matter in the coal has great influence on the NO reduction efficiency during the coal reburning process. The additional mineral matter can greatly improve the NO reduction efficiency of the coal reburning process. The effective sequence of the mineral matter is Na > K > Fe > Ca. The corresponding CO concentration in flue gas validated the catalyst mechanism of metal additives on NO-char reactions.