Water treatment carbon removal tower float level gauge failure
1. Failure phenomenon: The liquid level of the 4# carbon removal tower suddenly dropped. When the liquid level indicator of the instrument was 60%, the liquid level gauge of the process glass plate indicated 80%. The meter was running in the automatic state. As a result, the regulating valve is continuously closed, causing the actual liquid level of the system to continuously increase
2. Failure analysis:
(1) With the adjustment of the regulating valve, the change of the liquid level is linear, indicating that the regulating valve is normal.
(2) Check the process glass plate level gauge, the change is consistent with the actual liquid level, indicating that the process system is relatively stable.
(3) Check the electrical components on the instrument measuring board for damage.
(Heart) Check the condition of the buoy connecting parts and the inner buoy.
3. Troubleshooting
(1) Check the electrical components on the measuring board, and there is no obvious burn or damage.
(2) Checking with water, it is found that the zero point and range change greatly every time the watering check is performed. It is determined that there is a problem with the inner buoy, and the inner buoy is pulled out for inspection.
(3) Replace the inner float and re-calibrate to normal.
2 Coking oil tank displacer level gauge failure
1. Fault phenomenon: When the liquid level of the displacer level gauge is normally adjusted in the sealed oil tank, the meter always indicates 83% unchanged. Because the liquid level of the meter has an adjustment function, its wrong indication causes the adjustment of the adjustment valve to fail. , thus causing great fluctuations in production.
2. Failure analysis:
(1) When the buoy liquid level transmitter is in normal operation, the buoy medium is wax oil. When the wax oil is in a liquid state, the temperature is 90°C to 100°C, and the self-condensation phenomenon is about 50°C. Therefore, the buoy transmitter has heat tracing all year round. If the heat tracing fails and the temperature drops, the wax oil in the float will self-congeal and stick to the float. At this time, even if the actual liquid level occurs, the float level gauge cannot measure the change of the liquid level, and the output value does not change.
(2) Go to the site to inspect the float level transmitter: close the primary valve and open the empty valve. Taking measures to recover the condensate cannot release the medium, and it is suspected that there is dirt that blocks the anti-air valve. After removing the anti-air valve, it was found that the process medium was condensed in the cylinder and could not be released. At this time, check the heat tracing. The temperature of the intake pipe is about 100℃, but the temperature of the return pipe is about 30℃ (the site temperature was about 10℃ at that time). At this time, it can be determined that the condensation of the process medium caused by the poor heat tracing is just a failure. .
(3) Check the heat tracing system of the watch. Since the air inlet pipe of the watch is very hot and the temperature of the return water pipe is low, it is suspected that the steam trap is blocked. There is no problem after disassembling and checking. Re-cast the heat tracing, the return pipe is not hot, the problem is not solved. Recalling that in winter, the heat tracing air intake pipe leaked many times, and this phenomenon did not occur after treatment. Therefore, it is suspected that the heat tracing gasket of the float level gauge has blocked the air inlet due to multiple extrusions.
(4) Stop the heat tracing valve at the air inlet, open the plug of the heat tracing pad of the float level gauge, and find that there is no steam sometimes, so it is judged that the fault is that the air inlet gasket is blocked, which leads to the self-condensation of the wax oil, and the indication fails.
3. Troubleshooting: Open the heat tracing air inlet joint of the float level gauge, after processing the gasket, cast the heat tracing, and the liquid level indication is normal.
4. Measures to be taken: Regularly check the heat tracing of the meter. If the heat tracing is found to be leaking or not smooth, remove the fault in time.
3 No indication of liquid level in steam condensate recovery tank
1. Fault phenomenon: No liquid level indication in the steam condensate recovery tank.
2. Cause of failure:
(1) LT-8701-1 transmitter failure;
(2) The process flow is not open, resulting in no liquid level in the tank.
3. Treatment method: After on-site inspection, it was confirmed that the float level gauge was faulty. The float drain valve was opened, and no condensate flowed out. After removing the float and opening it, it was found that the tank had not been cleaned due to long-term use, resulting in a large amount of impurities in the tank. Filled, resulting in the displacer level gauge can not be used normally, clean up impurities and re-calibrate and put into use normally.
4 Displacer level gauge indicates large deviation
1. Fault phenomenon: The indication deviation of the float level gauge is large, and the effect is still not good after two-point calibration.
2. Analysis of the cause of the failure: In May 2007, the styrene technicians reported that the indication of LT-3005 was too large. After the instrument personnel used the 375 communicator for two-point calibration, the effect was still unsatisfactory. After analysis, it was believed that the torque of the buoy was After the tube is used for a long time, its rigidity has changed, and the general calibration method can overcome its error. The dry coupling point must be re-calibrated to make the torque tube work in the normal range, and then two-point calibration can be performed. Normal use. After using the above method to verify, the meter returns to normal.
3. Preventive measures: You must read and understand the instrument manual thoroughly, in order to more accurately judge and deal with the problem when there is a problem with the on-site instrument.
5 The indication of the electric displacer level gauge does not change
1. Fault phenomenon: When the liquid level of the electric displacer level gauge LT653 is adjusted normally, the meter always indicates 100% unchanged. Since the liquid level of the meter is regulated, its false indication brings great difficulty to the adjustment valve LV653 to adjust the liquid level. Process operators cannot use the meter for automatic adjustment, only manual control.
2. Failure analysis and treatment: When the buoy transmitter LT653 is in normal operation, the medium in the buoy is always in a relatively static state, which causes many impurities to settle in the buoy. When the position changes, the float is stuck, and the output value of the liquid level does not change. After arriving at the site, we first closed the stop valve at the root, opened the drain valve, and cleaned the inner wall of the buoy with water. After cleaning, the meter is running normally.
3. Preventive measures: regularly clean the buoy and float, and regularly check the operation of the buoy amplifier.
6 The indication of the electric float level gauge is low
1. Fault phenomenon: The electric displacer liquid level gauge LT101 measures the liquid level of ethylene in the comonomer tank. The glass plate liquid level gauge indicates that it is full, while the liquid level transmitter indicates about 40%.
2. Failure analysis and treatment: Check the components of the liquid level transmitter without any abnormality, check the gas phase and liquid phase for sewage discharge, and ethylene is discharged, open the buoy, and check the torque arm and buoy. The float has a trachoma, and the float is hollow. After filling with hexene, the weight of the float increases, and the measured liquid level is low.
3. Measures: Weld the float, put it back, calibrate it, and the liquid level will return to normal.
7 Inaccurate indication of smart buoy transmitter
1. Fault phenomenon: The ZTD intelligent buoy transmitter used in the field has inaccurate indications, and the zero point and range have been adjusted chaotically and cannot be put into use.
2. Processing method:
(1) “Mark the dry coupling point”, the operation steps are as follows:
(1) The hanging cylinder is heavy;
(2) Slide the entry handle to the locked position to expose the entry hole;
(3) Insert a 10mm deep concave socket wrench, go through the entry hole to the torque tube shaft clamp, clamp the nut, and tighten the clamp nut.
(4) Slide the entry handle to the released position, covering the entry hole.
(5) Operation via 275 (375) interface: base wood setting – sensor calibration – marking dry coupling point
——Mark the zero point according to the prompt of the HART protocol communicator.
(2) View the buoy parameter information through the 275 (375) interface, and modify the wrong ones.
(3) Check the density of the measured medium through the 275 (375) interface, and make corrections to the wrong ones.
(4) The PV bias is cleared.
(5) Carry out zero and span calibration of the transmitter.
8 The output linearity of the float level transmitter is not good
1. Fault phenomenon: The linearity of the LT322 output is not good.
2. Failure analysis and treatment: LT322 is a displacer liquid level transmitter, and the output linearity is not good. Check whether there is a card phenomenon in the movable part, and confirm that there is no. Check whether the upper limit of the range of the overload protection spring is disengaged, and confirm that it is not. Check whether there is any contact between the buoy and the outside of the measuring chamber, and confirm that there is no contact. Check the installation position of the measuring lever and the shaft seal frame, and find that the installation position is wrong. After re-installing it correctly, it is put into operation normally.
3. Preventive measures: The instrument personnel should be careful in the process of installation and repair to avoid carelessness and recklessness.
9 Displacer level gauge liquid level drop instrument does not follow the change
1. Fault phenomenon: The liquid level of LT-3106 suddenly drops to 60%, and the instrument display no longer operates.
2. Analysis of the cause of the failure: The instrument normally shows that the liquid level is 80%~-90%. When the liquid level drops to about 50% and the liquid level rises to 60%, the instrument display does not rise with the liquid level. The possible reasons are as follows Points: 1. The transmission unit of the transmitter is faulty; 2. The signal output is faulty; 3. The reason for the test child buoy.
3. Troubleshooting: According to the observation and the phenomenon reflected by the process, the reason for the failure of the transmission order and the transmission party is very small, and the inspection of the buoy should be started first. Empty the liquid in the buoy, discharge it as required, open the upper valve cover, detach the buoy from the transmitter, take out the buoy, and find that the buoy is stuck on the buoy. The liquid level of the instrument is connected with the main control room, and the instrument display is normal.
4. Preventive measures: buoys should be regularly inspected and discharged.
10 Liquid level fluctuations caused by vapor-liquid mixing
1. Fault phenomenon: liquid level fluctuation of isopentane recovery tank
2. Reasons for failure: Most of the isopentane required for the reaction is obtained through recovery. The liquid level in the recovery tank is inaccurate, which directly affects the process of the reaction. After recovery from the degassing chamber, the condensed substances still carry a large amount of reaction. The gas will cause pressure fluctuations in the tank, and the gas will also enter the float of the liquid level gauge, causing the liquid level to fluctuate and the measurement to be inaccurate.
3. Treatment method: close the upstream and downstream stop valves of the liquid level gauge, sweep open the discharge valve at the bottom of the buoy, after the gas is released, close the vent valve, sweep the stop valve to make the recovered liquid fill the buoy slowly, and the liquid level measurement restores a stable indication.
Post time: 28-03-22