When self-excited wet dust collectors used in environmental protection equipment operate in low-temperature environments, water mist icing can directly impact purification efficiency and equipment lifespan, potentially leading to secondary risks such as pipe cracking and electrical failures. To address this issue, a comprehensive antifreeze system must be established encompassing four key dimensions: liquid property control, equipment insulation design, intelligent monitoring systems, and process optimization.
Controlling the freezing point of liquids is a key approach to preventing freezing. Traditional water-based absorbents are prone to freezing at low temperatures. This can be achieved by adding antifreeze agents such as ethylene glycol or propylene glycol to lower the freezing point, creating a freeze-resistant mixture. For example, in a retrofit at a northern chemical plant, a mixture of water and 30% ethylene glycol lowered the freezing point to -18°C. This, combined with an electric heating system, completely eliminated nozzle clogging. Salt solutions such as sodium chloride and calcium chloride can also be used as antifreeze agents, but caution must be exercised regarding their corrosive properties and potential impact on equipment materials. Liquid preheating technology is also crucial. Raising the liquid temperature to above 5°C using a plate heat exchanger or electric heater effectively prevents freezing. For example, in a -20°C environment, preheating 10 m³/h of water from 5°C to 10°C requires approximately 15 kW of heating power. This parameter can be adjusted dynamically based on actual flow rate and ambient temperature.
The insulation design of the equipment must take into account both the main unit and the piping system. The casing of the self-excited wet dust collector should be constructed of high-efficiency insulation materials such as glass wool or polyurethane foam, forming a three-layer structure: "equipment casing + insulation layer + protective layer." Galvanized steel should be used for the protective layer to prevent moisture. In extremely cold environments of -30°C, the insulation layer must be at least 100 mm thick. The piping system should be equipped with electric or steam heating. The electric heating power should be designed to be 10-30 W/m², and the heating power should be automatically adjusted based on the ambient temperature using a PID controller. For example, when the ambient temperature drops below -10°C, the system can activate full heating power to ensure the pipe temperature remains above freezing.
An intelligent monitoring system is a key guarantee for anti-freeze protection. PT100 temperature sensors with an accuracy of ±0.5°C are placed at key locations such as the dust collector feed inlet, packing layer, and nozzle outlet, enabling real-time monitoring of temperature changes. Electromagnetic flowmeters with an accuracy of ±0.2% are installed in liquid delivery pipelines to monitor whether spray volume is meeting standards. Vibration sensors or infrared thermal imaging cameras are installed in areas prone to ice formation, such as nozzles and pipe blind ends, to detect ice thickness. Alarms are triggered when the ice exceeds 2mm. The system's tiered warning mechanism can set different response measures based on temperature thresholds, such as activating electric heating at -5°C and shutting down non-essential equipment and issuing an alarm at -10°C.
Process optimization should be based on equipment characteristics and operational requirements. A continuous spraying strategy maintains liquid flow and reduces the risk of static icing. A drain extension pipe with an aspect ratio of at least 15:1, two pipe diameter increments, and a 30° downward angle should be installed at the bottom of the gas storage tank to facilitate condensate drainage.
When equipment is shut down, the valve at the gas source power end must be closed. After three hours of power outage, a dedicated purge tool should be used to thoroughly clean the water film inside the bag to prevent residual moisture from freezing. In extremely cold northern regions, a double-layer transparent PVC insulation cover should be added to the inside of the inspection door. The tightness of the compressed sealing strip should be checked with a millimeter-level vernier caliper to ensure a tight seal.
Through optimized antifreeze liquids, enhanced equipment insulation, intelligent monitoring deployment, and process parameter adjustments, the self-excited wet dust collector can operate stably in low-temperature environments. During the design phase, heating interfaces should be reserved and antifreeze materials selected. During operation, the insulation layer integrity should be regularly inspected and temperature sensors calibrated to establish a full lifecycle antifreeze management system.
