Boiler Water Wall Thermal Spray

The circulating fluidized bed boiler, which is arranged on the hearth of the furnace, usually produces wear of the water wall tube. The wear rate (speed) is due to the different design of the furnace, coal, combustion adjustments and other factors of combustion, and some of the wear is very serious. Quality control in every aspect of the painting process. Check the wear of the pipe wall, and set up the welding process, use the wear-resistant metal layer, before the roughening treatment, after the wall jet and spray quality inspection and acceptance, do the furnace water to do a good job of cooling wall spray quality control is the key link . (Link: http://)
1. Checking the wear condition Checking the wear condition of the pipe wall is the first step of the wear in the furnace. According to the different wear conditions of various boilers, the development of the spray program can be done within a larger range of spray, but it can also be Used alone to repair spray. When planning to stop the overhaul of the furnace, or due to water leakage from water-wall pipes, and temporary repair of the explosion pipe, the wear of the furnace water wall pipe shall be inspected; in addition, according to the status of the boiler and the running time, the wear condition inspection shall be planned to achieve timely Find problems and timely treatment.
2. After the pre-spray treatment inspection, the water-wall tube has been worn out. According to the wear, the spray is ready. The principle of our treatment is: When the wear surface is relatively uniform, there is no local pit phenomenon, and the measured value of the wall thickness is greater than the theoretical strength, the surface roughness can be performed after thermal spraying; if the worn surface is seriously worn, the area is large and the wall thickness is Less than the calculated value of the theoretical strength, should be completed for local wear pits, the first repair welding, spray metal wear layer, wear a new pit for a long time, but also do repair welding. The water-cooled wall pipe is connected to the fin polishing pits and repair welding. In general circulating fluidized bed boilers, the water wall of the wall (including the surface of the wall fins) should be smooth, in which the collision or recesses accelerate wear.
3, repair welding due to circulating fluidized bed boiler water wall tube is made of a kind of high-quality carbon steel 20g before spraying, has good welding performance. At the same time, the pit or face is smaller, so welding can get good results.
In the evaluation of the effect of repair welding, the operational effect of our track was manual arc welding. After the pipe was cut, the performance was tested for more than 4,000 hours. The performance of the pipe was close to that of the base metal.
However, we must pay attention to maintenance welding process, should adopt a small standard welding method. Use small-diameter electrodes, small welding currents, arc welding to prevent overheating, to reduce the influence of heat affected zone; at the same time, to select skilled welders and weld the meat to the higher wall of the welded grinding. As a result, the welded portion of the pipe wall is maintained on the same plane as the other pipe wall.
The wear-resistant coating of the sprayed water-wall tube is worn for a certain period of time after the operation. The welding should take into account the adverse effects of metal wear on the wear-resistant layer of the alloy composition. Generally, it is necessary to repair the residual alloy. Part of the weld. If you do not wear the alloy composition, you must make a reasonable welding process.
The surface of the surface of the soldering surface that has been subjected to a high polishing treatment is inspected after inspection, and the next step can be performed only after the inspection is completed.
Surface roughness treatment 4 and spray front wall When thermally sprayed, particles of the melt sprayed material are sprayed onto the substrate at a high speed surface so that both the impact deformation and the surface of the substrate are inlaid with each other, and the surface roughness of the substrate is The surface roughness, which directly affects the strength of the bond between the coating and the substrate.
Use sandblasting to roughen the surface of the pipe wall to select sand, sand, sand spots and gas pressure and flow rate, but also depending on the operator's skill and experience in blasting operations to obtain a good surface roughness treatment effect.
Sandblasting should be quality tested and the surface roughness of the substrate should be appropriate and uniform. Surface roughening treatment should be sprayed as soon as possible to prevent oxidation, affecting the spray quality.
5, boiler water wall tube thermal spraying According to the working conditions of the circulating fluidized bed boiler, the thermal spray coating of the water wall tube should have the following conditions:
1) The coating must have a good combination on the substrate to prevent physical and chemical action under conditions of operation and shedding, even in unpredictable situations such as sudden water leakage, sudden overheating, etc.
2) The coefficient of thermal expansion of the coating should be approximately the same as that of the substrate.
The coating of 3) should not be a severe thermal insulation, the coating should not affect the normal heat exchange function of the water wall tube.
The coating of 4) will not damage the substrate, especially when the workpiece is heated to a high temperature.
5) Under the operating conditions, it has good abrasion resistance, heat resistance and oxidation resistance.
6) The lowest possible economic cost.
So far, it has entered the market, there are hundreds of spray powders, and nearly 100 kinds of spraying lines. It has been convenient to consider the different performances of the spraying materials selected by users. Circulating fluidized bed boilers can find their own suitable coating materials based on the four-coating spray coating with different performance requirements.
link:
Http://

Plasma abrasion resistant coating