Maintenance Strategy for Turbine Blades of Hydropower Station
- Details
- Category: Tungsten Information
- Published on Wednesday, 15 November 2017 16:37
Tungsten carbide has been widely used in spraying of various metal and nonmetal powders because of its high temperature resistance and excellent physical and chemical properties.
Water turbine is a power machine that converts the energy of water flow into rotating mechanical energy. It is mainly used to drive power generation in modern hydropower stations. In the actual operation of the unit, often encounter impact and cavitation impact, in the inlet position of blade or vane due to large particles of stone and other hard objects with large angle of attack directly impact, so that the coating local broken or repeated impact fatigue after coating caused partial damage, the damage also affects the adjacent area, and the quality of the equipment is seriously affected. Therefore, the protective coating of the turbine needs regular maintenance.
In the periodic maintenance of hydraulic turbine, the surface thermal spraying technology using metal and nonmetal as material is often used for coating repair. Tungsten carbide wear resistance, high temperature resistance, is the ideal material for repair of turbine protection coating.
It has been proved that tungsten carbide coating prepared by high pressure oxygen spraying has good abrasion resistance, but it is worse than stainless steel in cavitation resistance, in addition, the hard impact resistance of tungsten carbide coating is low, so the advantages and disadvantages of the prototype in the turbine site are obvious.
The turbine runner blade and guide vane on tungsten carbide coating repair is generally used in the unit repair, in order to timely repair of partial loss of coating, field spraying repair method can be used. For the fixed parts such as runner room, on-site spraying repair is more realistic. Field repair uses a manual spraying device, which requires higher technical requirements for the personnel, and the repair takes four steps:
1. Spray parts pretreatment, remove the surface rust layer, with stainless steel repair welding. 2. Dehumidification drying and dust removal, rust removal and surface polishing. 3. Nondestructive testing, the surface defects were repaired by argon arc welding technology, and then imported sand chips for surface polishing, until qualified. 4. Surface activation treatment. The service life of turbine blades repaired by tungsten carbide thermal spraying is greatly prolonged.
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