Analysis on Abnormal Rejects Discharge of a Medium Speed Pulverizer

A series of abnormal phenomena emerging in normal operation conditions of the medium speed pulverizers in a 600 MW unit are introduced. The effects of the primary air (PA) mass flow and nozzle ring passage area on the pulverizer rejects (PRs) discharge are analyzed. The results indicate that the root cause of all these abnormal phenomena is the lower nozzle PA velocity led by the narrowed nozzle passage area during the nozzle ring reformation. The problem is solved by changing the nozzle ring back to the original one. The experiences in this document can provide evidence and reference for pulverizer operation adjustment and PA nozzle ring reformation design.