电化学装置带集中力罐体的疲劳强度计算及刮板优化设计

【作者】 李岩；

【导师】 杨世明； 马法杰；

【作者基本信息】 天津工业大学 ， 机械工程（专业学位）， 2016， 硕士

【摘要】 在石油需求量和开采难度日益增加的背景下,如何高效地处理油田污水成为油田开采过程中亟待解决的问题之一。电化学方法因其不向污水中添加额外化学制剂的优点在处理污水方面有着特殊的优势。电化学方法通过利用电化学反应产生强氧化物质与胶体,将污水中杂质氧化或者吸附从而达到提高水质的目的。然而,电化学装置在运行过程中存在着阴极板聚集污垢的问题,这些污垢不仅影响反应效率,而且会减少极板的使用寿命。因此需要定期清除污垢以保证装置正常使用。常用清垢的方法有机械法、超声波法、化学法、倒极法等,本课题采用机械方法。由于本课题的电化学反应发生在罐体中而机械法除垢又需要外部提供动力,故罐体在承受内压的同时也承受外部循环变载荷,此时需要对罐体进行静强度和疲劳强度分析。应用ANSYS的多工况计算功能,获得了各种载荷状态下的应力分布,从而评定静强度；组合不同工况,获得了罐体的应力变化范围和危险点,应用疲劳分析后处理模块,得到了疲劳损伤系数,由此评定疲劳强度。通过评价网格密度说明了有限元结果的有效性。另外,机械法除垢仍然存在着改进的空间。如何准确地模拟机械除垢过程是改进机械除垢方法的基础。借助刨床加工的切削原理,确定了机械除垢中刮板的运动形式为沿着极板往复运动；通过分析污垢的形成过程,确定了应用土壤本构模型来模拟污垢的力学行为；参考金属刀具的几何参数和加工参数,确定了刮板的形状和运行参数。依据以上条件,应用LS-DYNA完成了机械除垢的模拟。基于机械除垢的仿真模型,确定机械除垢中刮板与污垢的接触力最小为优化目标,刮板的前角、运行速度和切削深度作为设计参数。设计虚拟正交试验,并利用Microsoft Excel中的回归分析功能对结果进行处理,得到了优化目标与设计参数的回归方程,进而利用MATLAB优化工具箱对设计参数进行了优化,并通过仿真模型验证了优化结果。更多还原

【Abstract】 In the background of increasing demand for oil and difficult exploitation, it becomes one of main problems in oil drilling that how to efficiently handle oilfield sewage. Electrochemical method has the special preponderance in wastewater treatment because of its advantages of not to add new chemicals. Electrochemical method use the strong oxidizing substance and colloid which product through electrochemical reaction to oxygenize and absorb the impurities in the sewage water in order to improve quality of water.However, when the electrochemical devices running, the fouling will together on the cathode plate which affects the reaction efficiency and reduces the service life of the plate. So the fouling should be removed in time. The means of cleaning fouling include mechanical method, ultrasonic method, chemical method, change electrode method and so on. The mechanical method is used in this paper and raises the research questions.First of all, the electrochemical reaction occurs in the pressure vessel and the pressure vessel under external circulation concentration as required by work. Thus, in order to ensure the safety of pressure vessel, the static strength and fatigue strength of pressure vessel must be evaluated. By the method of multiple-loading case, stress distributions of different loads were achieved to assess its static strength. The scope of the change of the stress and dangerous point were gained though the combinations of results from different loads. The exponent of the fatigue damage was acquired with the application of fatigue analysis post-processing in order to assess its fatigue strength.Besides, the mechanical method still can be improved. How to accurately simulate mechanical descaling process is the basis of improving the mechanical cleaning methods. With the cutting model of planer processing, the basic form of mechanical descaling was determined; By analyzing the formation of dirt, this paper determined to use soil constitutive model to simulate the mechanical behavior of soils; Imitating metal cutting tool geometry and process parameters, the mechanical descaling’s parameters and completing the simulation of mechanical descaling were also determined. Based on the simulation of mechanical descaling, the optimization goal that minimum the contact force between the mechanical cleaning blade and the dirt was determined, the design parameters include the blade rake angle, blade speed and cutting depth were defined as well. By orthogonal experiment and data processing and regression analysis in Microsoft Excel, the function of optimization objectives and design parameter was determined, and then objective function was optimized though the MATLAB optimization toolbox,in addition, through simulation models verified the optimize results.更多还原