电厂汽水系统腐蚀产物迁徙机理的研究

发布时间：2018-05-04 10:33

本文选题：腐蚀 + 汽水系统　；参考：《华北电力大学》2014年硕士论文

【摘要】：随着环境问题的日益突出,提高燃煤机组的经济效率,降低燃煤机组的污染物排放量成为燃煤机组的主要问题。目前,高参数,大容量的机组因其高经济性越发受到各界重视。但机组蒸汽参数的不断提高也增大了汽水系统腐蚀风险,使得热力管道受热面安全管理面临更大的挑战。本文主要针对汽水腐蚀产物迁徙问题,通过理论分析和计算分析得出影响汽水系统腐蚀产物生成和迁徙的因素。定性分析了不同参数对腐蚀产物迁徙的影响,还结合了电厂实际运行数据来研究腐蚀产物的迁徙过程。电厂汽水系统中腐蚀产物的产生部分主要是低温部分的流动加速腐蚀以及高温部分金属腐蚀。流动加速腐蚀主要是碳钢表面保护性的磁铁矿层(Fe304)在(单相)流动的水或是(两相)湿蒸汽中溶解的过程。金属高温腐蚀主要是超临界水或者是高温蒸汽和金属基体发生氧化反应,一般情况下生成Fe304和FeCr2O4组成的双层氧化层。在汽水系统中腐蚀产物主要有：Fe3O4、Fe(OH)2、α-Fe2O3、Fe2+、γ-Fe2O3、 Fe(OH)2+、Fe(OH)4-、Fe3+、Fe(OH)3等。根据E-pH图可以判断出,在汽水系统中最重要腐蚀产物是Fe2+,在所有E-pH图中固体-液体界面中都存在Fe-Fe2+平衡线,Fe2+的优势区域在整个E-pH图中占的份额最重,而且Fe2+是可溶性的,会随着汽水系统中的工质迁徙,这会导致锅炉汽水系统的进一步腐蚀。并且产生的Fe2+会使得金属管壁减薄,加重流动加速腐蚀。所以,电厂中应重点监测Fe2+以及其水溶性衍生物Fe(OH)+。为了降低超临界机组汽水腐蚀,可能存在给水系统最优含氧量,因为超临界水中溶解的氧促进了保护性氧化膜的形成。
[Abstract]:With the increasing of environmental problems , the economic efficiency of coal - fired units is increased , and the discharge of pollutants in coal - fired units has become the main problem of coal - fired units . At present , high - parameter and large - capacity units are paid more attention by all walks of life because of their high economic efficiency . However , the continuous improvement of the steam parameters of the unit also increases the risk of corrosion of the steam - water system , so that the safety management of the heating surface of the thermal pipeline is facing a greater challenge .

In this paper , the migration of corrosion products of steam - water system is analyzed by theoretical analysis and calculation . The influence of different parameters on the migration of corrosion products is analyzed qualitatively . The migration process of corrosion products is also studied by combining the actual operation data of the power plant .

The generation of corrosion products in the steam - water system of the power plant is mainly the flow - accelerated corrosion of the low - temperature part and the high - temperature partial metal corrosion . The flow - accelerated corrosion is mainly the process of dissolution of the magnetic iron ore layer ( Fe304 ) on the surface of the carbon steel in ( single - phase ) flowing water or ( two - phase ) wet steam . The high - temperature corrosion of the metal is mainly the supercritical water or the oxidation reaction of the high - temperature steam and the metal matrix , and the double - layer oxide layer composed of Fe304 and FeCr2O4 is generated in general .

The main corrosion products in the steam - water system are Fe3O4 , Fe ( OH ) 2 , 伪 - Fe2O3 , Fe ( OH ) 4 - , 纬 - Fe2O3 , Fe ( OH ) 2 + , Fe ( OH ) 4 - , Fe3 + , Fe ( OH ) 3 , etc . According to the E - pH diagram , the most important corrosion product is Fe - Fe ~ ( 2 + ) .

【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM621

【参考文献】