Experimental Study on the Dynamic Process of NO Reduction in a Precalciner.

The dynamic processes of NO reduction by coals and char at different O2concentrations have been investigated under the suspension conditions of a precalciner. The effects of cement raw meal, temperature, and O2concentration on NO formation and reduction were studied. The results show that there are two stages in the NO reduction process in the presence of O2. The first stage is the early homogeneous NO reduction by volatiles, and the second is the heterogeneous oxidation of char N. The reduction of NO by coal with a higher volatiles content is more significant. At this stage, the quantities of NO reduction by Datong coal and Chenzhou coal were found to be 1.08 × 10−6and 3.3 × 10−7mol, respectively. In turn, the reduction capacity of Chenzhou coal is much larger than that of Chenzhou char (the quantity of NO reduction by Chenzhou char was 1 × 10−8mol). Cement raw meal has positive effects on both NO reduction and NO formation. For the coal with the highest volatiles content (Datong), the total quantity of NO reduced by the coal increased from 1.08 × 10−6to 1.52 × 10−6mol when cement raw meal was present, whereas for Chenzhou char, the quantity increased only from 1 × 10−8to 4 × 10−8mol. For the two kinds of coals and the char, the effect of cement raw meal on NO formation was found to be relatively smaller. The temperature and O2concentration can also affect the dynamic processes of NO conversion by coals and char, and the effect of temperature on NO reduction is more significant. [ABSTRACT FROM AUTHOR]