Method for prolonging service life of fan impeller in acid environment

Abstract

The invention provides a method for prolonging the service life of a fan impeller in an acid environment, which comprises the following steps: (1) descaling the surface of an impeller shaft disc, then polishing, and finally removing corrosion; (2) carrying out first surfacing on the surface of the shaft disc by adopting 306 surfacing welding rods to form a transition layer; and (3) performing secondary surfacing on the transition layer by using a 316 surfacing electrode to form a protective layer. According to the method, the transition layer is overlaid on the shaft disc of the fan impeller by using the 306 overlaying welding rod, and the protection layer is overlaid on the shaft disc by using the 316L stainless steel welding rod, so that the problems of corrosion breakage and falling of the shaft disc can be effectively prevented.

Description

Technical Field

[0001] The invention belongs to the technical field of fan impellers and relates to a method for extending the service life of a fan impeller in an acidic environment. Background Art

[0002] In the dust removal and desulfurization equipment in the metallurgical and chemical industries, the impellers of the fans face serious corrosion problems. 4 ²⁻ and the acidic environment with a pH value of about 3, coupled with the influence of industrial and mining temperatures, greatly accelerate the corrosion rate of carbon steel impellers. In the past, attempts to change the impeller to 2205 bidirectional stainless steel (the shaft disc is cast steel) have improved the corrosion resistance of the impeller to a certain extent. However, due to the difficulty and high cost of processing the 2205 bidirectional stainless steel shaft disc, and the difficulty in ensuring the assembly size, the impeller shaft disc is still made of cast steel, and the efficiency of the 2205 bidirectional stainless steel impeller cannot be fully utilized. When the shaft disc is severely corroded, the dynamic balance of the fan impeller fails, the vibration frequency increases, and the safety risk of the impeller shaft disc falling off also increases. Summary of the invention

[0003] The purpose of the present invention is to provide a method for extending the service life of a fan impeller in an acidic environment in view of the problems existing in the prior art.

[0004] To this end, the present invention adopts the following technical solutions: A method for extending the service life of a fan impeller in an acidic environment comprises the following steps: (1) Descale the impeller shaft surface, then polish it, and finally clean it; (2) Use 306 cladding electrode to perform the first cladding on the surface of the shaft disc to form a transition layer; (3) Use 316L stainless steel welding rod to perform a second cladding on the transition layer to form a protective layer.

[0005] Furthermore, the current of the first surfacing in step (2) is 200-300A.

[0006] Furthermore, the current of the second surfacing welding in step (3) is 200-300A.

[0007] Furthermore, in step (2), the thickness of the transition layer is 1-5 mm.

[0008] Furthermore, in step (3), the thickness of the protective layer is 5-8 mm.

[0009] The beneficial effects of the present invention are as follows: by using 306 cladding electrodes to clad the transition layer on the shaft disc of the fan impeller, and using 316L stainless steel electrodes to clad the protective layer, the problems of corrosion, breakage and falling off of the shaft disc can be effectively prevented, the safety risks during the operation of the fan are reduced, and the replacement frequency of the impeller is reduced, the maintenance cost and the labor intensity of the maintenance personnel are reduced, and significant economic and social benefits are achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of the structure of the shaft disk transition layer and the protective layer of the present invention; In the figure, 1-shaft disk, 2-transition layer, 3-protective layer. DETAILED DESCRIPTION

[0011] The present invention is described in detail below in conjunction with embodiments: A method for extending the service life of a fan impeller in an acidic environment comprises the following steps: (1) First, descale the fan impeller shaft disc 1, then polish it, and finally clean it to ensure that the impeller shaft disc surface is clean and free of corrosion residue.

[0012] (2) Use 306 cladding electrode to perform the first cladding on the surface of the shaft disc to form a transition layer 2 with a thickness of 1-5 mm. In this embodiment, the thickness of the transition layer is 4 mm. During the first cladding process, the welding current is 200-300 A. In this embodiment, the welding current is 250 A. The welding speed should be moderate to avoid welding defects such as pores, slag inclusions, cracks, etc.

[0013] 306 cladding electrodes have good filling properties and certain corrosion resistance. They can form a relatively flat transition layer on the surface of the shaft disc with strong bonding with the base metal. This not only helps to repair the size reduction problem suffered by the shaft disc and rivets during the corrosion process, but also provides a more favorable basic surface for the subsequent cladding work of 316 stainless steel electrodes.

[0014] (3) Use 316 welding rod to perform the second welding on the transition layer 1. 316L stainless steel is known for its excellent corrosion resistance, especially in the presence of Cl⁻, SO 4 ²⁻ and other corrosive ions and an acidic environment with a pH value of about 3, a dense oxide film can be formed to effectively prevent the corrosive medium from further contacting the base metal, thereby greatly slowing down the corrosion rate of the shaft disc and rivets. After the second surfacing welding, a uniform and dense protective layer 3 with a thickness of 5-8mm can be formed. The protective layer 3 can effectively isolate the moisture, Cl⁻, SO in the working medium. 4²⁻ and the acidic environment with a pH value of about 3 to the corrosion of the shaft disc, in this embodiment, the thickness of the protective layer is 6mm. During the second surfacing process, the welding current is 250A, and the welding speed should be moderate to avoid welding defects such as pores, slag inclusions, cracks, etc.

[0015] The multi-layer surfacing method can make the weld layers fully integrated, and each layer fits tightly together to build an overall structure with strong protective capabilities. In addition, multi-layer surfacing can also help disperse and relieve the stress generated during the welding process, reduce the possibility of welding deformation, and ensure the dimensional accuracy and shape integrity of the impeller after repair, which is crucial for the balance and stability of the impeller under high-speed rotation.

[0016] This method can extend the service life of the impeller by more than 1 times, effectively prevent the corrosion, breakage and falling off of the shaft disc, reduce the safety risks during the operation of the fan, and at the same time reduce the frequency of impeller replacement, reduce maintenance costs and the labor intensity of maintenance personnel, with significant economic and social benefits.

[0017] This method is not only suitable for the repair of fan impellers, but can also be extended to the local repair of other equipment and facilities operating in the same acidic environment. It has wide applicability and practicality.

Claims

1. A method for extending the service life of a fan impeller in an acidic environment, characterized in that it comprises the following steps: (1) Descale the impeller shaft surface, then polish it, and finally clean it; (2) Use 306 cladding electrode to perform the first cladding on the surface of the shaft disc to form a transition layer; (3) Use 316L stainless steel welding rod to perform a second cladding on the transition layer to form a protective layer.

2. The method for extending the service life of a fan impeller in an acidic environment according to claim 1, wherein: The current of the first surfacing welding in the step (2) is 200-300A.

3. The method for extending the service life of a fan impeller in an acidic environment according to claim 1, wherein: The current of the second surfacing welding in step (3) is 200-300A.

4. The method for extending the service life of a fan impeller in an acidic environment according to claim 1, wherein: The thickness of the transition layer in step (2) is 1-5 mm.

5. The method for extending the service life of a fan impeller in an acidic environment according to claim 1, wherein: The thickness of the protective layer in step (3) is 5-8 mm.

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