Mill study on improving lime kiln efficiency

Optimization of the lime kiln requires an examination of the entire lime cycle. To increase the energy efficiency of the lime kiln, all auxiliary unit operations must function properly. It is also imperative that the lime and liquor in the system is of acceptable quality. We detail a kiln energy efficiency study performed by MWV Corp.' s Covington, VA, USA, mill. From a recausticizing standpoint, lime quality is much easier to control than liquor quality because liquor passes through many operations that are not under the lime kiln operator's control. Recausticizing is a fairly closed cyclical process where lime is concerned, so saturation of impurities to the point of operational issues must be considered. Specific cycle performance indicators (e.g., lime mud solids entering the kiln) must be viewed from a perspective that does not exclude their potential impact. To get a true picture of the cost of operating the lime cycle, all inputs must be considered. The four main inputs are power (electrical and fuel), fresh lime, caustic, and water. Application: Process engineers can use this detailed troubleshooting approach to help optimize various parts of a mill.