Measures to ensure reliable operation of electric heaters mainly include the following points: 1. Optimize the design and installation of electric heaters to prevent internal ash accumulation
The burnout of electric heating tubes is the most frequent fault among all faults, mainly caused by excessive internal ash accumulation that cannot be discharged. Since replacing electric heating tubes takes a long time, when multiple tubes burn out, the outlet temperature of the heater will not meet system requirements, affecting unit load for a long time or even causing shutdown, resulting in huge economic losses to the enterprise. Therefore, during the selection, system design, and installation stages of electric heaters, internal ash accumulation should be a key consideration. The heater manufacturer should be required to increase the distance between the heating tubes and the inner wall of the body, and arrange spare electric heating tubes at the bottom.
2. Improve ventilation and heat dissipation of the electric heater control cabinet to ensure the ambient working temperature does not exceed 25°C
Since the SCR power regulator generates a large amount of heat during thyristor operation and has a thyristor over-temperature interlock protection trip function, when the thyristor operating temperature exceeds 70°C, its temperature control component triggers, causing the interlock contactor to trip. During equipment operation, failures due to poor heat dissipation inside the control cabinet and high ambient temperature occur frequently. Therefore, improving ventilation and heat dissipation of the electric heater control cabinet and ensuring a suitable working environment temperature are very important. Before ordering the heater control cabinet, the manufacturer should be required to use high-power cabinet cooling fans, enlarge the air inlet area, design the cabinet size reasonably, and leave sufficient internal space. The power distribution room where the control cabinet is located should be equipped with at least two air conditioners to ensure the room temperature remains below 25°C.
3. Strengthen inspection of electric heaters to promptly detect and handle equipment abnormalities
During unit operation, operators from the power generation department, inspectors from the equipment department, and maintenance personnel should inspect the operation of the electric heater body and control cabinet daily, keep relevant records, and compare and analyze with previous similar data to identify potential equipment hazards in advance and handle them. Key inspection items should include: (1) Check that the valves in the pipeline are in the correct open or closed position, and do not change the valve status arbitrarily; (2) Check, record, and analyze the inlet and outlet air pressure of the electric heater, which should meet design requirements. If the air pressure is too low or too high, adjust the system operating parameters promptly; otherwise, it will accelerate damage to the heating tubes; (3) Check whether the grounding wire of the heater body is intact and securely connected to avoid electric shock accidents; (4) Check whether the cooling fan at the bottom of the SCR power regulator and the cabinet cooling fan are running well. If any fan stops, replace it immediately with a new one; (5) Check whether the air conditioner in the power distribution room where the control cabinet is located is operating normally, measure and record the room temperature, and handle any abnormalities immediately; (6) Measure the operating temperature of the SCR power regulator thyristor. If the measured value approaches 70°C, take measures to improve ventilation and heat dissipation to reduce the temperature, and if necessary, stop that group for inspection; (7) Record the maximum operating current of each group of electric heaters and compare with previous data. If the maximum operating current drops significantly, adjust the temperature controller parameters appropriately to increase the heater power.
4. Perform regular maintenance and overhaul of electric heaters
During unit overhaul or standby periods, the main power switch of the electric heater should be turned off, and relevant tests and disassembly inspections should be carried out. After the unit shuts down, the electric heater should be tested immediately to ensure early detection of problems and sufficient time for handling. Test items include: Measure and record the three-phase DC resistance of each group and the insulation resistance of each phase. If the insulation resistance is found to be lower than 1MΩ, disconnect the cable head and measure the insulation resistance of the cable and the heating tube separately to determine whether the problem is with the cable or the heating tube. If three-phase DC resistance imbalance is found, measure the cable and heating tube separately to determine the specific location and quantity. At the same time, perform core pulling inspection of the electric heater, remove internal ash accumulation, clean the heating tubes for descaling, check the appearance and tightness of the heating tubes, tighten all connecting wires inside the control cabinet, and check and calibrate the thermometer and temperature controller for proper operation. Before starting the unit, measure the insulation resistance of the heater again. If any group has low insulation resistance, do not energize it to prevent damage to the heating tube or cable. Pre-introduce the medium to dry the inside of the heater, and only energize it after the insulation resistance meets the requirements.
5. Strengthen training to master the operating standards and working principles of electric heaters
When minor defects occur in equipment, operators and maintenance personnel often fail to eliminate them in time due to unfamiliarity with the system and equipment principles, expanding the impact range. Therefore, training for operators and maintenance personnel should be strengthened to enable them to master the working principles of the equipment, learn to read electrical control schematics, accurately adjust equipment operating parameters, and promptly detect and handle equipment defects.
In summary, strengthening the management of electric heater equipment, carefully analyzing various fault causes, implementing preventive measures, combining prevention with maintenance and repair, and establishing and improving relevant management systems can improve the stable operation of electric heaters and bring good economic benefits to the enterprise.
