Recently, I learned that many power plant customers have encountered the problem of fluctuations in oxygen content during oxygen measurement.The technical department of our company went to the field to investigate and found the reason, helping many customers to solve this problem.
The power plant flue has zirconia oxygen measuring probes on the left and right sides of the economizer. Normally, the measured oxygen content is between 2.5% and 3.7%, and the oxygen content displayed on both sides is basically the same.But sometimes you encounter a very special situation. After the installation and debugging, everything is normal. After a period of time, the oxygen content displayed on one side will suddenly become smaller and smaller, or the oxygen content fluctuates up and down, and the lowest display The oxygen content is around 0.02%~4%.Under normal circumstances, users will think that the probe is damaged and replace it with a new probe, but after changing to a new probe, the same problem will occur after a while, and the probe can only be replaced.In this case, for the United States, Japan, and other domestic probes, the problem can only be solved by replacing the probe, but the cause of the probe damage is unknown.If the Nernst oxygen probe is used, the probe is also replaced, but the replaced probe is not damaged after inspection, and everything is normal when used in other positions.
How to explain this situation, here is an analysis and explanation:
(1) The reason for the fluctuation of oxygen and the damage of the probe is that the position of the probe is not ideal. The probe is installed just beside the fire-fighting water pipe inside the flue. Because the water pipe ruptures and leaks, water drops on the probe. There is a heater on the head of the probe with a heater temperature above 700 degrees. The water droplets form instantaneous water vapor, which causes fluctuations in oxygen content.In addition, because the flue is full of dust, the combination of water and dust will turn into mud and adhere to the probe, blocking the filter of the probe. At this time, the measured oxygen content will be very small.
(2) The United States, Japan, and other probes can no longer be used in this situation and can only be discarded. This is because this type of probe is a zirconium tube type, and when it encounters moisture, the zirconium tube will burst and be damaged when the temperature changes suddenly.At this time, it can only be replaced with a new probe, which brings great trouble and economic loss to the user.
(3) Due to the special structure of the Nernst probe, the probe will not be damaged in the event of sudden changes in moisture and temperature. As long as the probe is pulled out, the filter can be cleaned and the probe can be used again, which saves users the cost of use.
(4) To solve the problem of oxygen fluctuation, the best way is to change the position of oxygen measurement and fix the leaking pipe. But this is impossible to do when the unit is running, and it is also an impractical method.In order to enable users to work normally without affecting the operation of the unit, a simple and effective way is to install a baffle on the probe to prevent water from dripping directly on the probe, and then repair the leaking pipe when the unit is repaired. This does not affect production, saves costs, and satisfies normal online testing.
Our company has judged the leakage of water pipes at the flue locations of many power plants, and all of them have been resolved.
Post time: Jan-05-2022