Research on Pulverizer Rejects Characteristics for Medium Speed Mill

The characteristics of pulverizer rejects such as density, calorific values and ash component were tested in the laboratory for the ZGM95 medium speed mill, which indicates that the apparent and inherent characters of pulverizer rejects are quite different under different working conditions. The inner flow fields in the medium speed mill were numerically simulated by employing the commercial code of FLUENT. The results show that the static pressure and the flow rate at each nozzle ring are different from those of others due to the primary air entering the mill only from one side. The simulation validates that the air velocity at the nozzle ring is the highest and is an important factor to affect the discharging of the pulverizer rejects. In the range of simulated conditions, more pulverizer rejects will be discharged when increasing the size or the density, while few pulverizer rejects can be discharged when the pirmary air flow is quite large. The reconstruction suggestions were provided for the medium speed mill according to the simulated results.