The anti-pollution flashover design of wet electric demister insulators requires comprehensive consideration from multiple perspectives, including environmental adaptability, material selection, structural optimization, anti-pollution coatings, operation and maintenance, and monitoring and early warning. First and foremost, environmental factors are the fundamental design considerations. Wet electric demisters are commonly used to treat flue gas environments characterized by high temperature, high humidity, and corrosive gases, such as those found in the chemical, metallurgical, and power industries. Acidic gases (such as sulfur dioxide and hydrogen chloride), water vapor, and fine particulate matter (such as dust and salt) in flue gas easily deposit on the insulator surface, forming a conductive fouling layer. Especially in humid conditions, the conductivity of this fouling layer increases dramatically after absorbing water, leading to increased leakage current and a high risk of surface flashover. Therefore, the design must fully assess the flue gas composition, humidity, and temperature fluctuations. For example, high salt fog environments in coastal areas or chemical industries require particular attention to preventing electrolyte contamination, while rainy regions require enhanced moisture resistance.
The choice of insulator material directly impacts its anti-pollution performance. Traditional porcelain insulators have a hydrophilic surface, making them susceptible to the formation of a continuous water film under wet and contaminated conditions, which can create leakage current channels. Glass insulators, while offering high breakdown voltages, have limited pollution tolerance. Modern wet electric demisters tend to utilize high-performance composite insulators. Their silicone rubber sheds exhibit excellent hydrophobicity and water migration properties, so even small amounts of water adhere to the surface form isolated droplets rather than a continuous conductive film. Furthermore, high-aluminum or specially treated ceramic insulators can reduce contaminant adhesion by improving their surface finish. Their high mechanical strength also withstands arc burns, preventing flashovers caused by crack propagation.
Structural optimization is a key approach to improving pollution resistance. Wet electric demister insulators must withstand the combined effects of high-voltage electric fields, mechanical vibration, and flue gas scouring. Therefore, their structural design must balance electrical performance with mechanical strength. Increasing creepage distance can significantly delay flashovers. For example, using a double-shed or streamlined shed structure can significantly reduce the occurrence of flashovers. At the same time, the shed angle must be appropriately designed to ensure that condensed water droplets or flushing water quickly drain away under gravity, minimizing residence time. For critical components such as wall bushings, sealed insulated boxes can be installed. By maintaining a slight positive pressure and continuously blowing hot air, they isolate the cold, humid air from the outside and prevent condensation.
The application of anti-fouling coatings can significantly improve the insulator's resistance to pollution. Long-lasting anti-fouling flashover coatings (such as RTV and PRTV silicone rubber) form a hydrophobic film on the insulator surface. Their hydrophobic migration properties make the surface of the fouling layer hydrophobic, suppressing leakage current under wet and contaminated conditions. The coating requires regular inspection and re-application to maintain its protective effectiveness. For environments with severe acid mist, fluorocarbon coatings with higher corrosion resistance can be used. Their chemical stability effectively resists acid attack and extends the service life of the insulator.
The design of the flushing system must balance cleaning effectiveness and equipment safety. During wet electric demister operation, soluble salts or insoluble particles may accumulate on the insulator surface, requiring regular flushing to restore insulation performance. Flushing nozzles should use wide-angle, solid, fan-shaped ceramic nozzles to ensure full coverage and uniform water pressure, avoiding localized impact forces that could damage insulators. The flushing cycle should be adjusted dynamically based on flue gas dust content and humidity. For example, in high-humidity environments, the flushing interval can be shortened to every 2-4 hours, while in dry areas, it can be extended to once a day. After flushing, ensure that the insulator surface is completely dry to prevent residual moisture from causing flashover.
Dynamic adaptability to operating conditions is a key design consideration. Flue gas temperature fluctuations during equipment startup and shutdown can cause localized condensation on the insulator surface, forming conductive paths. Therefore, a temperature control system is required. Using electric heating cables or hot air furnaces, the insulator surface temperature should be maintained at 10-20°C above the dew point. Temperature sensors should also be installed for real-time monitoring to prevent overheating and material degradation. Furthermore, flue gas pressure fluctuations can also affect insulation performance. In high-altitude areas, the insulator creepage distance should be appropriately increased to compensate for the drop in discharge voltage due to low air pressure.
Developing a maintenance and management strategy is key to ensuring long-term stable operation. An insulator condition monitoring system should be established. By installing leakage current sensors and temperature and humidity sensors, real-time monitoring of insulation performance trends is essential. When leakage current fluctuates abnormally or approaches the tripping threshold, the system should automatically issue an alert, prompting maintenance personnel to inspect the insulator surface condition. During scheduled maintenance, insulators must be thoroughly cleaned to remove dust and salt buildup, and the coating integrity must be inspected. Aging or damaged insulators should be promptly replaced to prevent overall failure caused by local defects. Combining preventive maintenance with condition monitoring can significantly reduce the incidence of flashover accidents and improve equipment availability.
