The Study Of Surface Engineering Technology Application Of Slurry Circulating Pump Impeller In WFGD System

China is a coal-fired country, coal use accounts for more than 75% of primary energy. Coal will emit large quantities of sulfur dioxide, causing serious pollution to the environment. Thermal power plant flue gas desulfurization emissions, China mainly uses limestone/gypsum wet FGD technology (WFGD). In WFGD system, the absorber slurry circulating pump impeller is the key device, it is expensive, delivered solid phase gypsum slurry and high levels of chloride ions, causing serious wear and corrosion to the impeller. Short life, expensive cost of the impeller, and how to quickly repair the damaged impeller, improving its service life has attracted widespread attention.Impeller damage only happened on the surface, using surface engineering technology to the manufacture of slurry circulating pump impeller, can increase its corrosion and wear resistance, extend its service life of new pieces. For damaged impeller, it can be applied to repair the impeller back into use by surface engineering technology, Surface engineering technology reduces the cost of remanufacturing, and gets better performance of the remanufactured products.This paper taken different materials, structures and conditions of the slurry circulating pump impeller into account, designed and prepared Ni55AMo thermal spraying and fusing coating, WC-12Co HVOF coating, and polymer ceramic composite layer coating. Respectively tested erosion, wear, corrosion and cavitation of the coating, the resistance of the coating were tested. Based on the capability of the coating, optimized the structure and production process of different coating by taking its cost and production efficiency into account.Experimental studies have shown that HVOF prepared sub-micron WC-12Co coating holds high hardness, friction wear, cavitation and erosion resistance ability, coating thickness could be controlled, and is expected to be used in strengthening the new impeller; oxygen-acetylene flame spray-fusing prepared Ni55AMo thermal spraying and fusing coating holds well hardness, friction wear and cavitation erosion resistance capacity, also has excellent erosion resistance in chloride ions, and is suitable for repairing and strengthening duplex stainless steel impeller; TC02 is most excellent performance in polymer ceramic materials cement coatings, it is suitable for repairing the brittle materials such as high chromium alloy steel impeller.Actual use of that sub-micron HVOF WC-12Co coating can increase the life of new impeller more than 2 times; the impeller repaired by polymer ceramic composite layer coating compared to the original process, its service life increased more than 50%; the impeller repaired by Ni55AMo thermal spraying and fusing coating has been used for 9 months, that the equipment running well. The coating technology of repairing and strengthening of the impeller gets the economic, efficient, wear and corrosion resistance results.