热电厂主蒸汽管道用钢的腐蚀及防护

发布时间：2018-05-05 05:43

  本文选题：失效分析 + 主蒸汽管道　； 参考：《东北石油大学》2017年硕士论文

【摘要】：随着国内对电能需求越来越高,热电厂对发电设备可靠性的要求也越来越大,因此针对热电厂设备的失效分析就显得极为重要,而热电厂中的主蒸汽管道部分作为发电站的关键部件,因长期在高温高压条件下工作,容易产生裂纹、泄露等现象,严重时还可能造成人员伤亡,给企业带来不可估量的损失,因此如何提高主蒸汽管道的性能显得十分重要。本设计以工程实例为基础,对主蒸汽管道的失效模式、影响运行寿命的主要因素以及预防的方法进行了系统的分析,为发电厂主蒸汽管道的性能提供有力的保障,以达到降低事故频率、减少损失的目的。纳米复合镀层是一种重要的表面防护技术,通过在零件表面制备纳米复合镀层,可以有效的提高基体的各项性能指标,增加零件使用寿命,减少生产成本,因此广泛应用于许多工业领域。合金镀层中金属元素含量是决定Ni-Fe合金镀层性能的一个重要因素,如何提高铁元素在复合镀层中的含量,己成为当前复合电镀研究的热点。本文采用直流电沉积法及脉冲电沉积法在主蒸汽管道材质20#钢表面制备Ni-Fe合金镀层,并对其性能进行研究得到如下结论:研究了硫酸铁浓度、电流密度、搅拌速度、pH值及温度等参数对镀层中铁元素含量的影响,优选出最佳工艺参数为:电镀液中硫酸铁浓度20 g/L;电流密度1.5 A/dm2;搅拌速度300 rpm;pH值3.5;温度40℃。利用扫描电镜、X射线衍射仪对镀层的表面形貌、组织结构及元素分布情况进行检测,并探讨了Ni-Fe合金镀层的耐蚀、抗高温氧化机理,结果表明:采用脉冲电沉积法制得的Ni-Fe合金镀层的耐腐蚀性能强于直流电沉积方法,在相同的腐蚀介质中,Ni-Fe合金镀层的腐蚀电位增大,而腐蚀电流减小。采用脉冲电沉积法制备的Ni-Fe合金镀层经700℃、1.5 h高温氧化后,其抗高温氧化性显著优于纯镍镀层。经SEM分析,氧化后纯镍镀层中镍原子明显粗化,表面起伏较大;而Ni-Fe合金镀层中镍铁原子的共沉积抑制了镍晶粒的长大,镀层较平整。用脉冲电沉积法制备的Ni-Fe合金镀层,由于铁元素含量高,减小了镍基质氧化时的实际接触面积,因此提高镀层的抗高温氧化性。
[Abstract]:With the increasing demand for electric energy in China, the reliability of power generation equipment is becoming more and more important in thermal power plants, so it is very important to analyze the failure of thermal power plant equipment. As the key component of the power station, the main steam pipeline in the thermal power plant is liable to produce cracks and leaks for a long time under the conditions of high temperature and high pressure, which may also cause casualties and bring incalculable losses to the enterprises. Therefore, how to improve the performance of the main steam pipeline is very important. Based on an engineering example, this design systematically analyzes the failure mode of main steam pipeline, the main factors affecting operation life and the preventive methods, which provides a strong guarantee for the performance of main steam pipeline in power plant. In order to reduce the frequency of accidents and reduce losses. Nano-composite coating is an important surface protection technology. By preparing nano-composite coating on the surface of parts, the performance index of matrix can be improved effectively, the service life of parts can be increased, and the production cost can be reduced. Therefore, it is widely used in many industrial fields. The content of metallic elements in alloy coating is an important factor to determine the properties of Ni-Fe alloy coating. How to improve the content of iron in composite coating has become a hot spot in the research of composite electroplating. In this paper, Ni-Fe alloy coating was prepared on the surface of 20# steel by direct current electrodeposition and pulse electrodeposition, and its properties were studied as follows: the concentration of ferric sulfate, current density, current density were studied. The effects of stirring speed, pH value and temperature on the iron content in the coating were studied. The optimum technological parameters were as follows: ferric sulfate concentration 20 g / L in electroplating solution; current density 1.5 A / dm ~ 2; stirring speed 300 rpm ~ (-1) pH value 3.5; temperature 40 鈩，

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