【作者】 杨彦；

【导师】 幸福堂；

【作者基本信息】 武汉科技大学 ， 安全技术及工程， 2008， 硕士

【摘要】 离心风机在工业生产中占有很重要的地位,常常给通风、除尘、输运等系统提供动力。在实际运行中,由于风机的工质中含有大量粉尘,风机叶轮粘灰严重,造成风机因振动而频繁停机进行清灰动平衡。本文分两个部分,前一部分针对某钢厂所使用的风机,建立了全尺寸的三维模型。用数值计算的方法得到风机内部流动的具体分布,并结合现场的检查,确定风机叶轮粘灰及磨损的原因。其中,粘灰的两个必要条件是:①粉尘到达叶轮粘灰位置;②粉尘到达叶轮的部位存在有利于粘灰的流场。风机进口处粘灰主要原因是粉尘粒子近垂直的撞击非工作面;出口处粘灰是由于非工作面处有涡旋的存在。文章的后一部分是理论分析,主要建立了风机转子的数学模型。从转子动力学的角度分析了风机粘灰振动的原因及现场快速判断方法。对于风机这类刚性转子,粘灰块脱落而引起的振动具有一阶性,这也是利用在线监测装置判断风机是否是粘灰振动的理论依据。由于工厂现在大多装有风机在线监测装置,如动平衡仪,使维护人员能从众多风机故障中迅速判断由于灰块脱落发生振动。最后,将所设计的喷头引入到风机系统中,根据数值模拟的结果和实际情况,对喷吹系统进行了改进,利用水代替空气,增大了喷吹介质的动能。同时对喷嘴结构和安装角度进行优化,提出了最佳安装方式是喷嘴与后盘垂直距离20mm,与后盘夹角20°。此外,介绍了长短叶片控制风机出口处粘灰的方法。更多还原

【Abstract】 Centrifugal fan is very critical in the industry dust-cleaning system. It is usually used as power in the ventilating、dust-cleaning、delivery system. There is much dust in the gas of the fan. The dust aggregates in the impeller. That caused vibration of the fan. Under this situation, the maintenance department should stop the whole production system to cleaning the dust and do dynamic balance.This paper is divided into two parts. First, a full-scale three-dimensional model of the fan which is used by a steal&iron company is built. Flow field in the fan is numerical calculated by CFX. Compare to the spot observation, the reason which causes fan’s dust-sedimentation is determined. The two necessary conditions are:①The dust gets to the dust-sedimentary position;②The flow field of the dust-sedimentary position is good for the dust-sedimentation.The dust-sedimentation at the inlet of the fan is mainly caused by the impact between dust and non-working face. Eddy cause dust-sedimentation at the outlet of the fan.Then, the mathematical model of the fan rotor is made. The reason of the fan’s vibration which is caused by dust-sedimentation and quick judge way are analyzed in the view of rotor dynamics.For the fan which is belonged to the rigid rotator, the vibration that is caused by the dust sedimentation is first-order. That is used as the theory to judge if the vibration is caused by dust sedimentation.Usually, the company installs on-line monitoring device, such as balance apparatus. It is possible for the maintenance department judge the dust-sedimentation vibration failure quickly out of the many other failures.Finally, the designed nozzle is installed in the rotating fan. Based on the stimulation result and the practice, the spray-system we are now using is improved. Air is replaced by water to increase blow-medium’s kinetic energy. The structure and the position of the nozzle are optimized. The best install way is 20mm from nozzle to the back disk. The included-angle is 20°.Furthermore, long-short blade is introduced to reduce dust-sedimentation at the outlet of the fan.更多还原