​Corrosion Prevention for Multi-Blade Fan Impellers

Corrosion Prevention for Multi-Blade Fan Impellers

This paper analyzes the causes of corrosion in multi-blade fan impellers and proposes corresponding treatment methods. Corrosion in mechanical equipment poses a significant challenge in chemical production. Due to the unique nature of production media, equipment frequently undergoes corrosion from various chemical elements, primarily hydrogen chloride gas. Severe corrosion affects mechanical equipment and piping components during production, with centrifugal blower impellers experiencing particularly severe corrosion. Multi-wing fan impellers are exposed to hydrogen chloride gas containing high moisture content. 1. Impeller Material: Chromium-nickel alloy is used, yet corrosion severity remains high. Blades made of 3–6 mm thick chromium-nickel material corrode to paper-thin thickness. Environmental and production process factors: 2 Hyperbolic and chordal values 2. Hyperbolic and chord values Anti-corrosion methods Initially, the multi-wing fan impeller surface was coated with 470 resin, but operational results showed limited effectiveness. Within days, centrifugal fan vibration reached 10–20 mm/s amplitude, severely impacting production. Based on actual production conditions, further anti-corrosion exploration for the multi-wing fan impeller was conducted. Considering the production process medium, temperature, impeller diameter, and rotational speed, the specific anti-corrosion method is as follows: (1) First grind and sandblast the impeller to remove corrosion. (2) Apply 901 or 470 resin evenly onto the impeller body, then bond polyester cloth to the impeller surface and blades. (3) Apply 901 or 470 resin evenly over the polyester cloth and bond glass fiber mat. Ensure the bonded surface is smooth. (4) Apply 984 or 470 resin evenly over the bonded mat, align with talcum powder trough, and bond glass cloth. (5) Finally, apply 984 or 470 resin, aligning with the talcum powder groove. After applying anti-corrosion treatment to the multi-wing fan as described above, allow 3 to 6 hours (depending on ambient temperature) for the anti-corrosion material to fully cure. Reinstall the impeller rotor section and simultaneously restore the fan housing. Upon completion of restoration, conduct a thorough inspection of the multi-wing fan. After confirmation, perform dynamic balancing via online testing. Install the dynamic balancer's speed probe and connect it to the vibration probe. Then, based on the impeller diameter, rotation direction, and the angle indicated by the dynamic balance, calculate the number and position of counterweight plugs. Typically, for impellers under 1200mm in diameter, use 60-80g counterweights; for diameters between 1200mm and 1800mm, use 60-80g; and for diameters over 1800mm, use 90-120g. When vibration values reach 3–5 mm/s, dynamic balancing is complete, and the multi-wing fan enters normal operation. Significant advancements in the production and application of multi-wing fan impellers have reduced maintenance time and costs. The shortest downtime required is 30–60 days.