溶有CO_(2)的发电机内冷水的pH控制策略研究

Research on pH control strategy for internal cooling water in generators with dissolved CO_(2)

发电机内冷水处理的核心在于控制内冷水pH在8.0~9.0范围内,通过微碱性环境实现对铜导线腐蚀的控制,因此发电机内冷水pH的监测是一项重要工作。但由于内冷水电导率很低,受液接电位、流动电位以及纯水温度补偿等因素影响,难以使用传统pH电极准确测定其pH,且内冷水非常容易溶入CO_(2),常规计算型pH仪表并不适用。依据Kohlrausch离子独立移动定律建立了溶有CO_(2)、以NH_(3)为碱化剂的发电机内冷水中pH与电导率、氢电导率之间的数学模型,通过动态模拟试验对该模型的准确性进行了验证。利用模型计算得到的pH最大误差为0.03,表明该模型的准确性较高。在现场工业试验中将该模型应用于指导NH_(3)的投加,相比利用传统pH电极控制碱化剂加药量,内冷水铜质量浓度由60.0μg/L以上降低至5.0μg/L以下,铜导线的腐蚀得到抑制,取得了较好的应用效果。

The core of generator internal cooling water treatment is to control the pH of the internal cooling water within the range of 8.0-9.0,to realize the control of copper wires corrosion through a slightly alkaline environment.It is quite important to monitor the pH of the internal cooling water in generators.However,due to the low conductivity of the internal cooling water and the influence of factors such as liquid contact potential,flow potential,and pure water temperature compensation,it is difficult to accurately determine its pH using traditional pH electrodes,and it is very easy to dissolve CO_(2)in the internal cooling water.Therefore,conventional computational pH instruments are not suitable.A mathematical model was established for the relationship between pH,electrical conductivity,and hydrogen conductivity in internal cooling water of generator with dissolved CO_(2)and NH_(3)as alkalization agent,based on Kohlrausch’s law of ion independent movement.The accuracy of the model was verified through dynamic simulation experiments.The maximum error of pH calculated using the model was 0.03,indicating the high accuracy of the model.This model was applied to guide the on�site NH_(3)dosing in on-site industrial experiments.Compared with using traditional pH electrodes to control the dosage of alkalizing agents,the copper concentration in the internal cooling water was reduced from above 60.0μg/L to below 5.0μg/L,indicating that the corrosion of copper wires was suppressed with good application results.