SCAL型间冷系统循环水中溶解氧含量变化及其对材料腐蚀的影响

Change of Dissolved Oxygen Content in Circulating Water of SCAL Intercooling System and Its Effect on Material Corrosion

SCAL型间接空冷机组已经成为我国北方地区火电发展的趋势,但是该系统的循环水水质控制及防腐问题尚未解决。通过对SCAL型间冷系统结构的分析、调研以及现场挂片实验,对循环水中溶解氧含量变化以及对材料腐蚀的影响进行研究。结果表明,SCAL型间冷系统在运行期间基本处于密闭状态,外界氧气难以扩散进入,系统循环水中溶解氧的来源为系统运行前除盐水中溶解的氧气。碳钢的腐蚀反应是系统中溶解氧主要的消耗方式。循环水溶解氧含量降低时,碳钢和纯铝的腐蚀速率都会降低。

The SCAL indirect air cooling unit has become the trend of thermal power development in northern China, but the problems of circulating water quality control and anti-corrosion of the system have not been solved.This paper studies the change of dissolved oxygen content in circulating water and its influence on material corrosion through the analysis and investigation of the structure of SCAL type intercooling system and on-site coupon test. The results show that the SCAL type intercooling system is basically in a closed state during operation, and it is difficult for external oxygen to diffuse into the system. The source of dissolved oxygen in the system circulating water is the oxygen dissolved in the demineralized water before the system operation. Corrosion reaction of carbon steel is the main consumption mode of dissolved oxygen in the system. When the dissolved oxygen content of circulating water decreases, the corrosion rate of carbon steel and pure aluminum will decrease.