Year1
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Shanghai Duomu Industrial Co., Ltd.
Contact person Zhou
Wear mechanism of water-cooled wall tube of circulating fluidized bed boiler and pulverized coal furnace There is a big difference. On the one hand, a large amount of flue gas and solid particles scour the water-cooled wall tube during the rising process. On the other hand, due to the effect of internal circulation, a large number of solid particles fall back along the four walls of the furnace, violently scouring the water-cooled wall tube. . Especially in the protruding parts of the transition zone between the water wall tube and the refractory material layer. Since there is no upward airflow, the solid particles coming down along the water-cooled wall tube form vortexes, which play a planing effect on the local water-cooled tube wall.
The main factors that affect the wear of the water-cooled wall are the influence of the flue gas flow rate. The higher the flue gas flow rate, the more serious the wear. The amount of wear is proportional to the cube of the flue gas flow rate. The greater the primary air volume, the greater the amount of wear. In addition, the greater the secondary air volume, the more severe the disturbance to the combustion situation in the furnace will be, and the greater the wear of the water wall. The influence of flue gas particle concentration. The greater the particle concentration in the flue gas, the greater the wear of the water wall. Because the larger the number of particles, the stronger the impact and erosion on the pipe wall. During the operation of a circulating fluidized bed boiler, the higher the load, the greater the bed density and bed differential pressure, indicating that the greater the particle concentration, the greater the amount of wear. Due to its specific combustion method, the density of solid materials in the circulating fluidized bed boiler is dozens to hundreds of times that of the pulverized coal boiler. Influence of fuel properties: The greater the hardness and ash content of fuel particles, the stronger the cutting effect on the water-cooling wall tube wall and the greater the amount of wear. Especially when coal gangue or other high-hardness fuels are mixed, the running time of the water-cooled wall pipe burst will be greatly shortened. Influence of the quality of installation and maintenance The quality of installation and maintenance of the boiler is not good. For example, the fins on the heating surface are not fully welded, causing a large number of particles to leak out and causing wear to the side of the water wall tube. Or a large number of raised parts after welding are left on the surface of the tube panel, forming particle eddy currents and aggravating wear. Influence of the power field of the boiler itself. Due to the uneven distribution of flue gas flow velocity in the furnace, the flue gas flow velocity at the four corners is much greater than that in the middle, so the wear is more serious than in other parts.
At present, most domestic water-cooled wall repairs use electrospraying, and electrospraying will cause many problems during the repair process. For boilers burning inferior coal, the anti-wear period is short, generally no more than three months, and the spraying construction requirements are high. . There are many spray coating manufacturers, and the quality varies from good to bad. Wrinkles are easy to appear after spraying, and they are easy to fall off during operation, or even fall off in large areas, becoming new wear and tear points that damage the welding properties of water-cooled wall tubes. The electrosprayed alloy materials penetrate into the base metal, destroying its welding properties, and easily causing the water-cooled wall tubes to burst. The secondary treatment cycle is long and the maintenance workload is large. After the boiler bursts and the boiler is shut down, it must be cooled and polished before cladding and secondary spraying. Electrospraying has a short service life, spraying every year, and the cumulative total cost is high.
With the many problems that arise in electrospraying and the various disadvantages of this process raised by power plants that cannot be solved, plasma powder cladding technology has made many achievements in the boiler water wall repair industry and has been well received by the majority of power plants.
The plasma powder cladding machine is a metal surface modification equipment independently developed by our company with completely independent intellectual property rights. This cladding process is to improve the wear resistance, corrosion resistance, impact resistance and other properties of the metal surface. Its technical advantages are that the cladding layer has a smooth surface, no cracks, and no pores. The wear-resistant and durable thickness is much higher than the thickness of the sprayed layer, and it is controllable. Compared with the mechanical extrusion of particles of the sprayed layer, the cladding anti-wear layer is a metallurgical bond. , on the basis of ensuring the above, under the condition of high combined strength and the same thickness, the wear-resistant life is times the life of the spray coating. Generally, the thickness of the cladding layer can be adjusted according to the user's requirements and the characteristics of the coal entering the furnace. To ensure the wear-proof life, the minimum guarantee is one year, and the maximum guarantee is more than one year.
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