Electromagnetic flow meter flow output is inconsistent with the actual, zero shaking, unstable
Several electromagnetic flowmeters are used in the gasification unit, and the faults encountered during the test run of the gasification unit are as follows:
1. The flow signal suddenly drops or has no indication
The process operator reported that the flow value of the gray water flow meter from the circulating gray water cooler suddenly dropped, and according to years of instrument maintenance experience, the main reason for this situation is that the insulation between the electrodes is bad or short-circuited, causing the signal to not be sent out. After careful inspection, it was found that the signal socket was corroded, so it was cleaned and dried with water, and it was normal after loading. Of course, in addition to the above reasons, there may be dirt deposition on the inner wall of the measuring catheter, the lining of the measuring catheter is damaged, and the specific reasons are dealt with.
2. The output signal is shaken
Instrument personnel found during inspection that the output signal of the electromagnetic flowmeter wobbled badly, checked and confirmed that the measured flow body did not fluctuate or pulsate, and the pipeline was full of liquid, after careful inspection, the electromagnetic flowmeter itself was not faulty, and it was found that there was a equipment maintenance personnel welding a joint not far away, which was determined to be caused by electromagnetic interference when the welding machine was working. The meter indicates normal when away from electromagnetic interference.
3. Zero point is unstable
When the process is stopped, the zero point of the concentrated mortar flow meter is unstable, and the inspection finds that there is dirt deposition in the pipeline measured by the meter, which is attached to the inner wall of the measuring tube, resulting in the zero point change of the flow meter, and the dirty goods on and near the electrode are removed. After the dirt is removed, the zero point is found to be some change. After the zero is re-corrected with bt200, the table shows normal. Of course, the reasons for zero point instability in addition to the above analysis may also be the following three reasons:
The pipeline is not filled with liquid or there are bubbles in the liquid;
Whether there is leakage in the pipeline;
Whether there is external electromagnetic interference;
4. The measured value does not match the actual value
In the case of ensuring that the liquid in the measured pipeline has been filled with the sensor and is stationary, after re-adjusting the zero point of the table with bt200, there is an error between the measured value and the actual value. After careful inspection, it is found that the range setting of the converter is wrong, and the indicator is normal after re-setting the correct range in line with the table. The reasons for the discrepancy may also have the following aspects: The sensor installation position is not appropriate, the pipe is not full or the measured liquid contains bubbles, such failures are mainly caused by poor pipe network engineering design, and related equipment is not perfect; The insulation of the signal cable is reduced.
