白鹤滩电站水轮机泥沙磨损评估研究

为预估白鹤滩电站水轮机的泥沙磨损,为水轮机选材、大修及防护方案的制定提供数据支撑,本文利用水力机械磨蚀测试系统中的旋转圆盘磨蚀测试工位,根据白鹤滩电站的过机泥沙条件及过流部件过流条件,对相应泥沙和过流条件下过流部件备选材料的磨损规律及磨损性能进行了实验研究。通过试验研究获得不同含沙浓度、过流速度磨损条件下不同材料表面的磨损深度,并通过多元线性回归法拟合试验数据获得不同材料的磨损率公式。利用磨损率公式及磨损率-粒径关系式,对一定运行时间范围内真机主要过流部件转轮及导叶区的磨损深度进行了预估,结果表明磨损较严重的部位为活动导叶下端面及转轮叶片出口靠近下环处。机组运行10年后,水轮机上述区域的磨损量分别为2.66 mm、1.75 mm。依据国家标准《反击式水轮机磨损技术导则》,两个过流区域的磨损量均较小,对机组正常运行影响较小,满足10年大修周期要求。

Evaluation on sand abrasion to Baihetan hydraulic turbines

Evaluation on sand abrasion to turbines can provide data support to the selection of anti-abrasion materials and the decision on anti-abrasion strategies and overhaul plans for the turbines that will work at the Baihetan hydropower station. In this work, we have conducted an experimental study on the anti-abrasion performance and wear behavior of the materials possibly to be used for the turbines, and simulated the conditions of flow and sands passing through the turbines on the rotating disc test stand of an erosion test system for hydraulic machinery (ETS-HM). Different sand concentrations and flow velocities were adopted for the simulation tests, and resultant abrasion depth on the sample material surface due to sand impacting damage was measured after completion of the tests. Empirical formulae of abrasion rate for different materials were obtained by fitting the test data with a multivariable linear regression method. Applying these formulae, we estimated possible sand abrasion to the proto turbines for a certain period of operation, including runner, guide vane, and other major components of the flow passage. The estimation reveals that the most severe abrasion occurs on the end walls of guide vanes and at the blade outlet edges near lower runner ring. At these two locations, surface abrasion depth will increase up to 2.66 mm and 1.75 mm after ten years of operation respectively, which fall in the allowable range specified in the national standard GB/T 29403—2012.