水离子积对pH值在线监测的影响

The Effect of the Ionic Product of the Water on On-line pH Value Monitoring

介质pH值是炼化生产的重要过程参数之一,普遍采用在线方式进行监测,并用实验室测量数据对在线测量设备进行标定,这种做法忽略了在线测量温度与实验室温度的差异以及测量时电极种类的差异,存在导致生产工艺控制偏差,进而造成生产浪费或产品品质问题的风险。针对此情况,进行了理论分析及理论分析结论的实验室和现场试验验证。结果表明,升温对pH值小于5水溶液的pH值影响非常小,升温对pH值大于9水溶液的pH值影响较大。饱和甘汞电极为参比的pH电极测量值与理论值基本一致,差分电极的测定数据与理论数据不一致。

The pH value of the medium is a crucial process parameter in refining and production,which necessitates accurate online monitoring and calibration using laboratory measurements.However,this approach overlooks the potential discrepancies caused by temperature variations between online and laboratory measurements,as well as differences in electrode types during measurement.Consequently,these practices can lead to deviations in production process control,resulting in waste or compromising product quality.To address this issue comprehensively,theoretical analysis was conducted and subsequently validated through both laboratory experiments and on-site trials.The results revealed that temperature has a negligible impact on the pH value of aqueous solutions with a pH below 5,however,it exerts a significant influence on solutions with a pH above 9.Furthermore,while the pH values measured by reference electrodes employing saturated calomel are consistent with theoretical values,differential electrode measurements do not align with theoretical data.