储油罐底腐蚀深度统计的极值理论应用

Application of extreme value theory in the corrosion depthstatistics of storage tank bottom

摘要:

为准确了解储油罐底的腐蚀状态,掌握储油罐在长期服役过程中罐底最大腐蚀深度的统计规律,更科学有效地评估储油罐的剩余使用寿命,采用广义极值分布(GEV)作为统计模型,对罐底腐蚀深度的最大值进行极值统计,构造相应的统计模型,并采用L-矩法计算模型的参数值,分析罐底腐蚀深度的统计规律.采用该方法对胜利油田某联合站内的3个储油罐底腐蚀深度进行统计分析, 结果表明:罐底腐蚀最大深度符合极值Ⅲ型分布(Weibull分布),而不是极值Ⅰ型分布(Gumbel分布),并均通过柯尔莫哥洛夫检验.极值Ⅲ型分布较极值Ⅰ型分布能更好地拟合罐底腐蚀最大深度的统计规律.

Abstract:

To get the corrosion condition of tank bottom accurately, master the statistical rule of maximal corrosion depth of the tank bottom in long-term service, and evaluate the residual service life of storage tank more effectively, the generalized extreme value (GEV) distribution was adopted as statistical model for the corrosion depth of the tank bottom, and the statistical law of the corrosion depth was analyzed. L-moments method was used for calculating the values of the parameters. The method was used to three tank bottoms in one unite plants from Shengli Oilfield, and the results showed that the maximum corrosion depth accorded with the GEV distribution Ⅲ (Weibull distribution), which got though the Kolmogorov inspection. The GEV distribution Ⅲ can fit the statistical rule of maximum corrosion depth better than that of the GEV distributionⅠ.