中速磨煤机的石子煤特性研究

Research on Pulverizer Rejects Characteristics for Medium Speed Mill

对ZGM95型中速磨煤机排放的石子煤进行了密度、发热量和灰成分的实验室化验分析,发现不同工况下排放的石子煤在外观和物性上都存在较大差别。利用FLUENT程序对中速磨煤机内的流场进行模拟,结果显示,由于一次风是从磨煤机一侧吹入,导致不同喷嘴环处的入口静压和流量呈不均匀分布。模拟验证了喷嘴环处的风速最高且是影响石子煤排放的一个重要因素。在模拟工况范围内,随着石子煤粒径和密度的增大,石子煤的排放量也越来越多,而在风量较大的情况下,石子煤的排量基本很少。根据数值模拟结果对中速磨煤机目前存在的问题提出了若干改造建议。

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.