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 failures, 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 cannot meet system requirements, affecting unit load for a long time or even causing shutdown, resulting in huge economic losses for the enterprise. Therefore, during the selection, system design, and installation stages of electric heaters, internal ash accumulation should be a key consideration. It is required that the electric heater manufacturer increase the distance between the heating tubes and the inner wall of the body, and arrange the backup electric heaters 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 operation and has a thyristor overtemperature interlock protection trip function, when the thyristor working temperature exceeds 70°C, its temperature control element is triggered, causing the interlock contactor to trip. During equipment operation, failures due to poor heat dissipation inside the electric heater control cabinet and high ambient temperature occur frequently. Therefore, improving ventilation and heat dissipation of the electric heater control cabinet and ensuring its working environment temperature is crucial. Before ordering the heater control cabinet, it should be required that the manufacturer uses high-power cabinet cooling fans, enlarges the air inlet area, designs reasonable cabinet dimensions, and leaves 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 check the operation of the electric heater body and control cabinet daily, keep relevant records, and compare with previous similar data to identify potential equipment hazards early and handle them. Key inspection items should include: (1) Check that all valves in the pipeline are in the correct open or closed position, and do not change 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 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 operating properly. If any fan stops, replace it immediately; (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 lower the temperature, and if necessary, stop the 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 heater power.
4. Perform regular maintenance and servicing of electric heaters
During unit maintenance or outage periods, the main power switch of the electric heater should be turned off, followed by relevant tests and disassembly inspections. After unit shutdown, the electric heater should be tested immediately to ensure early detection of problems and sufficient time for handling. Test items include: measuring the three-phase DC resistance of each group and the insulation resistance of each phase, and keeping records. If the insulation resistance is found to be below 1MΩ, disconnect the cable head and measure the insulation resistance of the cable and heating tube separately to determine whether the problem is with the cable or the heating tube. If three-phase DC resistance is unbalanced, 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 to remove scale, check the appearance and tightness of the heating tubes, tighten all connecting wires in the control cabinet, and check and calibrate the temperature gauge and temperature controller for proper operation. Before starting the unit, measure the insulation resistance of the heater again. If low insulation resistance is found in any group, do not energize it to prevent damage to the heating tubes or cables. Introduce medium in advance to dry the interior of the heater, and only energize it after the insulation resistance meets requirements.
5. Strengthen training to master the operating standards and working principles of electric heaters
When minor equipment defects occur, operators and maintenance personnel often fail to address them promptly due to unfamiliarity with the system and equipment principles, expanding the impact. 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 servicing, and establishing comprehensive management systems can improve the stable operation of electric heaters and bring good economic benefits to the enterprise.
