Study on dynamic response model of elastic support roller rolling on coal layer

Abstract

Coal-fired power generation is expected to continue to be used in the future. In this process, coal must first be pulverized, and vertical roller mills are used. However, during the pulverization process, abnormal vibration called self-excited vibration rarely occurs. In previous study, a small element testing machine was used to investigate this problem. The relationship between the slip ratio and the coefficient of friction between the roller and the powder showed a characteristic change when abnormal vibration occurred, but it is not clear whether this is the cause of the self-excited vibration. To investigate whether the characteristic relationship between the slip ratio and friction coefficient observed during abnormal vibration is a cause of self-excited vibration, a simulation model was created by applying the relationship between the slip ratio and friction coefficient in the experiment to a mechanical model for a small element testing machine and comparing the results with those of the experiment. As a result, the model was able to represent the vibration frequency that was confirmed in the experiment when abnormal vibration occurred. However, the dependence of the roller horizontal acceleration on the running speed could not be confirmed. The relationship between the slip ratio and the coefficient of friction could not be reproduced, but the change in the coefficient of friction could be reproduced. The vibration modes that are observed when abnormal vibration occurs were confirmed, but it is not clear whether they can be regarded as self-excited vibration or not.