Arc Spraying Technics And Wear Resistant Materials For Water Wall Of CFB Boiler

The Circulating Fluidized Bed (CFB) boiler, a high efficiency and low emission combustion technology developed in recent years, has been the preferred combustion equipment due to its advantages such as broad adaptability to fuel, high efficiency of combustion and desulfurization , flexible load regulating performance and cinder's multi-utilities. However, the water wall tubes which work in an atrocious ambient of high temperature, erosion of the solid materials and corrosion of the flue gas are liable to be weakened or even damaged. The problem not only seriously affects the running safety of boiler, but also causes huge economic loss and has become a technical problem to be solved urgently.Directing at the general-exist problem of wear for water wall in CFB boiler, the paper expatiated operating principle of CFB boiler and wear mechanism of its water wall based on the clearly understanding of CFB boiler work condition, the influence elements of wear and antiwear methods. In the paper, arc spraying technology to prevent water wall of CFB boiler from abrasion and erosion was studied and the influence of arc spraying technology parameters on coating performance was also analyzed and the optimal paramerers presented at last by experiment of bonding strength between coats, test of anti-wearing and anti-eroding at normal temperature. The results showed that the arc current is the key parameter affecting the performance of the coatings, spraying distance and atomizing air pressure are in the next place while the arc voltage affects the performance slightly. The bonding strength enhances as the arc current increases but the abradability declines if the are current is overlarge. At a certain arc current, overlong or overshort spraying distance goes against the stability of the coatings and the worst stability appears when the spraying distance and atomizing air pressure were varied reversely. In addition, the technology was applied to the YG-75/5. 29-M5 CFB boiler of Huang Gu Thermal Power Plant and the running results show that a well effect of wear-resistant can be got with the coating made according to the optimal parameters above and can meet demands of site project in practice.In conclusion, the electric arc spraying with optimal parameters is proved a valid water wall antiwear means in CFB boiler.