RTO is a technology that can effectively and thoroughly control VOCs. Because of its special use process requirements, it will also become a kind of equipment with certain dangers. Therefore, designers have made abnormal alarms for possible faults in the actions of each part of the RTO control system, and reduced the damage to the equipment through necessary emergency treatment.
In the RTO system, the severity of the fault is also distinguished, which is mainly divided into general fault and serious fault. The occurrence of general fault will only affect the local action of RTO, and the occurrence of serious fault may cause system shutdown. Therefore, the maintenance personnel are required to have a comprehensive understanding of RTO fault and have the ability to deal with the fault. In case of fault, emergency treatment can be carried out according to the fault point prompted by the "alarm screen" on the touch screen and with reference to RTO operation instructions. Piaohua technology lists and analyzes some common faults of RTO.
1. Abnormal power supply
Contact the power supply department to check whether the RTO system has been powered; Check relevant power switches and circuits; Pay attention to whether the air switch and fuse are blown.
2. Fan failure
① Whether the communication between PLC and display screen is normal, such as whether the communication line is loose and falling off.
② If the fan stops automatically, the power cabinet can be powered off and restarted.
③ If the fan motor fails, it may lead to motor overcurrent and alarm.
3. Low air pressure alarm of fan
① Check the motor (whether it operates and whether there is abnormal noise), belt (whether it is broken or loose), bearing and circuit (whether the motor is powered on normally).
② Observe the rotation of the fan. If there is no abnormality in the rotation, replace the differential pressure switch.
③ If it still cannot return to normal after restart, professional technicians are required to check and repair.
4. Low compressed air pressure
① Confirm whether the manual valve on the main compressed air pipeline is opened.
② Confirm whether the air supply system is normal and observe whether the pressure indicated by the pressure gauge is 0.4 ~ 0.8MPa. If yes, check whether the parameter setting of the pressure switch is correct (0.6MPa) or damaged; If not, contact to check whether the air compressor and dryer work normally.
③ Check the compressed air pipeline for leakage. If it is normal, check the compressed air pipeline for leakage.
5. Abnormal action of pneumatic valve
(1) If all valves do not operate, the possible causes of the problem are as follows:
① Check whether the compressed air pressure is within the normal range of 0.4 ~ 0.8MPa and whether the manual valve on the main compressed air pipeline is opened.
② Whether there is any problem with the DC power supply of PLC cabinet and whether the fuse is blown.
(2) If a single valve acts abnormally, the possible root causes of the problem are as follows:
① Check whether the manual valve on the small compressed air pipe corresponding to the valve is opened.
② Check whether there is any problem with the intermediate relay of the PLC cabinet corresponding to the valve.
③ Check whether the solenoid valve of the valve acts. First, check whether the solenoid valve coil is energized; Secondly, check whether there are sundries blocked in the solenoid valve. Generally, it can continue to be used after disassembly and cleaning. If there is a problem with the cylinder, it needs to be replaced or repaired by professionals.
④ Observe whether the on-site valve position indicator is in place. If the on-site valve position indicator is in place, readjust the remote valve position indicator.
⑤ Another possibility is that the valve sealing surface is stained with iron filings and other sundries, so that the valve cannot be completely closed, and the compressed air has been rushing out from the exhaust port of the two position five-way valve. Usually, this situation will disappear automatically as the sundries fall off, otherwise the nearest inspection door should be opened to remove the sundries.
6. Unsuccessful ignition
Open the combustion control cabinet and press the reset key of the combustion controller to re ignite. If the burner still fails to ignite after repeated times, find the cause according to the following ways:
① Observe the closing of each small lamp of the combustion controller, and analyze the cause of no fault according to its prompt.
② Check whether the servo motor is normal. Check whether the connecting rod is loose. Whether the gas balance valve is in the proper position.
③ Check whether the ignition solenoid valve is faulty.
④ Check whether the ignition pipeline is opened and whether the pressure is normal (the pressure behind the pressure reducing valve is about 1-2kpa).
⑤ Whether the pressure in front of the main pressure reducing valve is 20-50kpa and the pressure behind the pressure reducing valve (5-7kpa) is normal. If the pressure behind the pressure reducing valve is abnormal, adjust the pressure reducing valve or replace the pressure reducing valve.
⑥ Wipe the igniter and flame detector head and try again.
⑦ Check whether the high-pressure igniter ignites.
⑧ Whether the flame detector is faulty.
⑨ Check whether the air supply of combustion fan is normal and whether it operates normally.
⑩ Check whether the cooling air of flame detector is too large, turn it down and try again; Whether the flame detection cooling air is turned off. If it is turned off, the temperature at the end of flame detection may exceed 65 ℃, and the automatic protection action of flame detection may lead to ignition failure.
If the above problems do not exist, but the ignition cannot be successful, professional personnel are required to readjust the combustion system.
7. Sudden flameout of burner
Open the combustion control cabinet, press the reset key of the combustion controller and restart the burner. If the burner still cannot operate normally after repeated times, find out the cause according to the following ways:
① Whether the pressure in front of the pressure reducing valve (20-50kpa) and the pressure behind the pressure reducing valve (5-7kpa) are normal. If the pressure behind the pressure reducing valve is abnormal, adjust the pressure reducing valve or replace the pressure reducing valve.
② Check whether the servo motor is normal. Check whether the connecting rod is loose. Whether the gas balance valve is in the proper position.
③ Check whether the pressure switch of combustion supporting fan acts.
④ Check the flame detector for problems.
⑤ Check whether the high temperature limiter acts.
⑥ Check whether the cooling air of fire detector is too large, resulting in a small fire. Turn down the ignition and try again; Whether the flame detection cooling air is turned off. If it is turned off, the temperature at the end of flame detection may exceed 65 ℃, and the automatic protection action of flame detection may lead to ignition failure.
If none of the above problems exist, but the flameout occurs again after successful re ignition, professional personnel are required to readjust the combustion system.
8. Upper limit of exhaust overtemperature
(set temperature 355 ℃), RTO will give an alarm and stop automatically. Check whether there is a problem with the exhaust thermocouple according to the on-site thermometer. If the on-site thermometer shows no overtemperature, replace the thermocouple and restart RTO. If the on-site thermometer also shows overtemperature, analyze the causes according to the following conditions:
① Whether the exhaust gas inlet temperature is too high. The normal inlet temperature of RTO is normal temperature.
② Check the 6 main switching butterfly valves of RTO system for failure. If the valve fails, RTO regenerator cannot store and release heat normally, which will also lead to over temperature of RTO outlet.
③ Check whether the heat storage body is intact. If the heat storage body is blocked, broken or collapsed, the heat exchange efficiency will be reduced, so as to improve the exhaust temperature.
④ Check that all production line exhaust valves are closed. If it is closed for a long time, the amount of waste gas entering RTO is too small, which will lead to over temperature of RTO outlet.
9. Oxidation chamber temperature ultra-high alarm
Over high temperature alarm of oxidation chamber: RTO will stop automatically at this time.
① Check whether there is a problem with the thermocouple. It can be judged according to the temperature displayed by the three thermocouples and the combustion control cabinet. Under normal conditions, the reading error of any two is ≤ 150 ℃.
② Check whether the proportional valve of the combustion system operates normally. Whether the fuel pressure fluctuates too much.
③ If the concentration of waste gas is too high, check the production process.
10. Abnormal temperature change in oxidation chamber
① Check whether the proportional valve operates normally.
② Although the automatic control system can stabilize the furnace temperature, the sudden change of waste gas volume is too large, which will make the temperature rise faster or slower. Therefore, try to keep the imported waste gas volume relatively stable.
③ Check whether there is a problem with the thermocouple.
④ Whether the control cabinet is well grounded. If not, the thermocouple signal interference may lead to abnormal temperature display.
11. RTO temperature deviation is large and abnormal
During the automatic operation of RTO, the abnormal action of a certain part will lead to a large deviation in the temperature on both sides of the furnace. When the temperature deviation occurs when the system is not abnormal, it needs to be checked from the following aspects:
① Check whether the damper in the furnace operates according to the normal procedure.
② Check whether the side connection between the change-over valve cylinder and the change-over valve is loose or not. Under normal circumstances, the positions on both sides of the change-over valve are the same, and there are basically no excess threads to be seen.
③ If the above inspection confirms that there is no problem, it is necessary to check whether the detection of temperature probe is correct, that is, judge whether the indication of RTO thermocouple is normal.
The above contents basically include some common faults and troubleshooting methods of RTO equipment during operation. In addition, the RTO can be inspected and repaired by professional personnel according to the instructions, so as not to cause damage to the RTO.