Analysis and measures of influencing factors of online detection error of pure water pHmeter

Regarding the online measurement application of pure water pH meter, when it is used to measure the pH value of pure water in thermal power plants, it often has large errors due to the influence of flow and temperature, unstable fluctuations in meter indications, slow electrode response and electrode usage. Short life and other situations, this article will analyze the reasons for the online measurement error of the pH meter and propose specific solutions. In routine maintenance, we found that adjusting the flow valve, the pH value will change. The impact of flow changes on pH measurement may exceed 1 pH, while the qualified range of boiler feed water pH in thermal power plants is 8.8~9.3, with only 0.5 pH space. This makes the value displayed by the meter sometimes lose its reference meaning and cannot play the role of chemical supervision. At the same time, it makes the automatic ammonia dosing system misjudgment and dosing indiscriminately, which is easy to accelerate the corrosion of the thermal system. Because the pH measurement is the activity of hydrogen ions, not the concentration of hydrogen ions.