New generation of low NO/sub x/ calciners

Many countries-especially the USA, Canada, and European countries-have enacted stringent requirements for the emission of NO/sub x/ from new or upgraded cement plants. In many cases the NO/sub x/ emission must be lower than 500-800 mg NO/sub x//NM/sup 3/ of dry gas (corrected to 10% oxygen) which is equivalent to approximately 1.10-1.76 kgNO/sub x//MT clinker for a modern pyroprocessing system. Actual field data show that while some existing plants can meet this emission level, most plants cannot. Therefore, new plants must be capable of attaining NO/sub x/ emissions that are below most existing plants. To meet these emissions requirements, it is logical to consider redesign of the precalciner. With this in mind, studies were carried out to determine the best methods for reducing NO/sub x/ in the calciner area and to incorporate these findings into a new generation of low NO/sub x/ calciners.