Study on Internal Cooling Water Quality and Coils Corrosion of Large Generators

摘要

In recent years, along with the improvement of manufacture and operation levels of large generating unit, the operation and management levels of large generators internal cooling water are more and more important. As the main editors of the power industry standard DL/T 801? Requirements for internal cooling water quality and It's system in large generators? (revised vision), the authors have researched the problems of large generators internal cooling water occurred in these years. With the increasing of unit capacity and the development of stator coils design and manufacture , the requirement of the large generators internal cooling water quality is higher and higher. This paper takes the quality of large generators internal cooling water for object and researches the blockage fault in stator coils caused by copper corrosion. The authors analyses the reasons of the coils copper corrosion in PH value, oxygen content, conductivity, etc. And it comes to the conclusion that PH value is the main factor on copper corrosion in stator coils. Some suggestions were put forward about the quality of internal cooling water to improve the standard DL/T 801. For example, decrease the copper content, distinguish the PH value between different oxygen contents, delete the index of hardness, modify the value of conductivity on basis of the relationship between conductivity and pH value, etc. (the advises above were adopted in the revised vision of DL/T 801). Meanwhile the question that how to choice the oxygen-poor system or oxygenrich system was discussed in the paper, which shows that the oxygen-rich system isn't always rich in oxygen. And the oxygen-rich system can't work as well as it should be in theory. The paper tries to conclude the views and basis on the process of standard revision. It can help the professionals to understand and execute the new standard. Also it can provide the basis for the operation control of new generator unit internal cooling water and the technical transformation of old generator units.