Multiple electromagnetic flowmeters were used in the gasification unit. The failures encountered during the commissioning of the gasification unit were as follows:
1, sudden drop in flow signal or no indication
The process operator reported that the flow rate of the gray water flow meter from the circulating grey water cooler suddenly dropped. According to years of experience in instrument maintenance, the main reason for judging this situation was the deterioration of the insulation between the electrodes or the short circuit, which caused the signal to be sent. stay home. After careful inspection, it was found that the signal sockets were corroded, so they were cleaned and dried with clean water and returned to normal after installation. Of course, in addition to the above reasons, it is also possible to measure the dirt deposition on the inner wall of the catheter and measure the lining of the catheter to be destroyed, and the specific reasons for the specific treatment.
2, output signal shaking
When the instrument personnel inspected, the output signal of the electromagnetic flowmeter was shaken severely, and the inspection confirmed that the measured fluid was not fluctuating or pulsating. Under the condition that the pipeline was full of liquid, after careful inspection, the electromagnetic flowmeter itself was not faulty and it was not far away. There is an equipment maintenance personnel welding a joint, which is determined to be caused by electromagnetic interference when the welding machine works, and the flow meter indicates normal after the electromagnetic interference.
3, zero instability
When the process is stopped, the zero point of the concentrated grout flow meter is not stable. It is found that the scale inside the pipeline measured by the watch is fouled and adheres to the inner wall of the measuring tube, which causes the zero point of the flowmeter to change and removes the dirt on the electrode and near the electrode. After the dirt, it was found that there was some change in the zero point. After re-zeroing with bt200, the table showed normal. Of course, the reason for the instability of the zero point may be the following four reasons in addition to the analysis above:
The pipe is not full of liquid or air bubbles in the liquid;
Whether there is a leak in the pipeline;
No influence of external electromagnetic interference;
4, the measured value does not match the actual value
In order to ensure that the liquid in the pipe under test has filled the sensor and is stationary, after recalibrating the zero point of the watch with the bt200, there are still errors between the measured value and the actual value. After careful inspection, it was found that the range setting of the converter was wrong, and After setting the correct range according to the table, the indication will be normal. The reasons for the discrepancy may also include the following aspects: The sensor is not properly installed, the tube is not full, or the measured liquid contains air bubbles. This type of failure is mainly the pipe network engineering design. Bad, as well as related equipment is not perfect; signal cable insulation ability is reduced.
First, the site and the main control room should check whether the connection of the cable is correct, and then check whether the junction at the terminal or the cable connector is damp, which results in the cable insulation ability declining; the sensor upstream flow condition does not meet the requirements. The flow status upstream of the sensor is often limited by the installation space and does not comply with the specified requirements. For example, a spoiler near the spoiler does not have a sufficiently long straight pipe section. These factors will affect the accuracy of the measurement. There are silt layers or wall on the inner wall of the measurement tube. It is worn away, which changes the flow area and affects the measured value; the resistance between the electrodes of the sensor changes or the insulation of the electrode drops. This fault is often caused by the ingress of rainwater at the terminals, causing them to become wet. Remove moisture to restore insulation.
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