Brief Introduction of Power Plant Boiler Spraying Technology

       Boiler spraying, thermal spraying, supersonic arc spraying, boiler heating surface anti-wear and anti-corrosion, boiler water wall anti-wear spray, deflector anti-wear, anti-wear plate installation, longitude and latitude anti-wear, grille anti-wear, CFB boiler anti-wear technology

During the operation of the power plant boiler, some heating surface pipes will cause erosion and wear, high temperature oxidation and high temperature corrosion, and in severe cases, leakage and pipe burst accidents will occur. In order to solve this problem, it is a good method to use metal thermal spraying to make a surface strengthening layer on the failure part. But in order to achieve the desired effect, we must also pay attention to the following key technical points.

1. The advanced performance of coating equipment is a necessary condition for making high-quality coatings:

Metal thermal spraying includes four categories: flame spraying, plasma spraying, arc spraying and explosive spraying. Among them, plasma spraying and explosive spraying are not suitable for on-site operation of power plant boilers, while arc spraying and flame spraying can meet on-site operating conditions, but flame spraying speed is slow, The construction period is long, and the sprayed parts are prone to stress concentration and deformation, but the arc spraying technology can well meet various conditions for large-scale application of power plant boilers.

With the continuous improvement of science and technology around the world, the arc spraying technology has also achieved major breakthroughs. The birth of supersonic arc spraying equipment has greatly improved the performance of the coating. Because the alloy particles atomized by the supersonic arc spraying equipment are uniform and the flying speed exceeds the speed of sound, the bonding strength of the coating is greatly improved, and the density and homogeneity of the coating are very good. The six sets of arc spraying equipment currently used by our company are all supersonic arc spraying equipment. Over the years, tens of thousands of square meters of reinforced protective layers have been produced on the heating surface pipes of power plants across the country, and all have achieved good results.

The supersonic arc spraying equipment used by our company is a spraying equipment imported from abroad. Compared with the domestic general arc spraying machine, it has several advantages, which are mainly reflected in: the spraying technology uses the arc burning on the end of the wire to uniformly send The incoming wire is melted, and the supersonic airflow accelerated by the Laval nozzle atomizes the melted wire into particles with fine particle size and uniform distribution, which are sprayed to the workpiece to form a coating. Due to the use of Laval nozzle acceleration technology, the melted particles fly at supersonic speeds of 386M\S. The molten particles are mainly combined with the substrate in mechanical, physical and metallurgical ways. The bonding strength can reach more than 50Mpa and the porosity is less than or equal to 0.9%. Therefore, the prepared coating has high uniformity, good compactness, good bonding strength and porosity. inferior advantages.

2. Sufficient coating design is the basis and premise to ensure the effect of surface protective layer:

At present, there are many units engaged in metal thermal spraying projects all over the country, but the technological development is very unbalanced. Many units do not understand the working condition parameters and analyze the reasons for failure when undertaking projects, no matter whether the heating surface pipeline fails due to erosion and wear, or fails due to high temperature oxidation or high temperature corrosion, or whether it is sulfate type corrosion or sulfide type corrosion, let alone. It will consider whether there is the influence of steam soot and flue gas corridors, and the same material is used to make the protective layer. It is conceivable that this kind of coating design, regardless of the working conditions and without analyzing the cause of the failure of the workpiece, cannot guarantee the use effect at all. Therefore, our company attaches great importance to the research on metal thermal spraying technology. It is a council member of the National Thermal Spraying Association and a council member of the China Surface Engineering Association. It understands and masters the most advanced metal thermal spraying technology, and must carry out every project. Carefully analyze, understand the working conditions parameters, analyze the cause of the failure of the workpiece, and make a coating design on this basis to ensure the pertinence of the engineering design and the effect of use.

According to the specific working conditions and failure analysis of the heating surface of your factory, we have selected the relevant spraying wire, such as the low temperature reheater with high hardness, excellent erosion resistance, and high temperature oxidation and high temperature corrosion resistance. The material is GP-SFM; the water-cooled wall thinning tube and the sootblower channel are too high, and the material that resists high temperature corrosion and high temperature oxidation is particularly good, and has considerable thermal hardness, and is resistant to erosion and wear at high temperature. Material, namely GP -SFF chrome-nickel alloy wire, the specific performance indicators of the above materials are shown in the technical scheme.

3. Key technologies in construction:

Coating design is the basis and premise of the project's use effect. Advanced equipment performance is a necessary condition for obtaining a good coating. However, if the construction ability and construction quality cannot keep up, a satisfactory protective coating cannot be produced.