Pressure vessel corrosion pit phosphating device and phosphating method

Abstract

The application discloses a pressure vessel corrosion pit phosphating treatment device, which comprises a base, a power supply and a constant temperature heating device are sequentially arranged in the base from bottom to top, a phosphating liquid stainless steel container is arranged above the constant temperature heating device, a stirring device is arranged in the phosphating liquid stainless steel container, the constant temperature heating device and the stirring device are connected with the power supply, and the bottom of the phosphating liquid stainless steel container is connected with a spraying pipeline and a liquid pumping pipeline respectively, so that the corrosion protection coating can be conveniently sprayed on the inner surface of the metal cylinder; the application further discloses a pressure vessel corrosion pit phosphating treatment method, which comprises the following steps: rust removal, grease removal and ash removal treatment are carried out on the corrosion and thinning parts of the inner surface of the cylinder; phosphating treatment is carried out on the corrosion and thinning parts to form a phosphate conversion film; the phosphate conversion film is subjected to sealing treatment; and washing and drying treatment are carried out, so that the phosphate conversion film formed by the method is firmly combined with the base and is not easy to fall off under steam erosion, and the corrosion resistance of the corrosion and thinning parts is enhanced.

Description

Technical Field

[0001] This invention belongs to the field of surface treatment technology for metal parts, and relates to a phosphating treatment device for corrosion pits in pressure vessels. This invention also relates to a phosphating treatment method using the above-mentioned phosphating treatment device for corrosion pits in pressure vessels. Background Technology

[0002] Steam enters the pressure vessel through the extraction pipe. The inner surface of the vessel's cylinder at the connection point is constantly subjected to erosion from the incoming steam and the changing steam flow, making the cylinder at the connection point susceptible to corrosion. This is especially true for pressure vessels that have been in operation for a long time, where the inner surface of the cylinder connected to the extraction pipe exhibits severe corrosion thinning. If anti-corrosion treatment is not applied to the inner surface of the cylinder at the connection point, the corrosion will worsen, jeopardizing the safe operation of the pressure vessel.

[0003] In existing technologies, anti-corrosion coatings are typically applied to the inner surface of the pressure vessel's cylinder during the manufacturing process using methods such as enamel lining, glass lining, rubber lining, electroplating, spraying, painting, and spraying anti-corrosion coatings. However, due to equipment limitations, conventional spraying devices often have fixed nozzles, making it difficult to perform anti-corrosion treatment on the inner surface of the cylinder at the pressure vessel's nozzle connections. The nozzles cannot penetrate the cylinder at the nozzle connections, making it impossible to accurately perform secondary treatment on the corroded and thinned areas of the inner surface. Furthermore, existing anti-corrosion coatings have poor stability. During pressure vessel operation, the inner surface of the cylinder is constantly subjected to the erosion of steam intake and the erosion caused by the changing steam flow. Conventional anti-corrosion coatings are prone to peeling off under steam erosion, failing to provide long-term effective protection for the inner surface of the pressure vessel's cylinder. Summary of the Invention

[0004] The purpose of this invention is to provide a phosphate treatment device for corrosion pits in pressure vessels, which solves the problem that conventional spraying devices in the prior art are very difficult to use for anti-corrosion treatment of the inner surface of the cylinder of pressure vessels.

[0005] The present invention also provides a phosphating treatment method using the above-described pressure vessel corrosion pit phosphating treatment device.

[0006] The first technical solution adopted in this invention is a pressure vessel corrosion pit phosphating treatment device, including a base, inside which a power supply and a constant temperature heating device are arranged sequentially from bottom to top, a stainless steel container for phosphating liquid is installed above the constant temperature heating device, a stirring device is arranged inside the stainless steel container for phosphating liquid, the constant temperature heating device and the stirring device are both connected to the power supply, and a spray pipe and a liquid extraction pipe are respectively connected to the bottom of the stainless steel container for phosphating liquid.

[0007] The first technical solution of this invention is further characterized by:

[0008] One end of the spray pipe is connected to the bottom of the stainless steel container of phosphating solution, and the other end of the spray pipe is equipped with a phosphating solution nozzle. The spray pipe is also equipped with a spray motor and a spray controller. One end of the liquid extraction pipe is connected to the bottom of the stainless steel container of phosphating solution, and the other end of the liquid extraction pipe is equipped with a phosphating solution suction nozzle. The liquid extraction pipe is also equipped with a suction motor and a suction controller.

[0009] The phosphating solution nozzle is made of stainless steel, while the phosphating solution suction nozzle is made of silicone. The diameter of the suction nozzle is twice that of the phosphating solution nozzle.

[0010] The second technical solution adopted in this invention is a phosphating treatment method for corrosion pits in pressure vessels, which uses the aforementioned phosphating treatment device for corrosion pits in pressure vessels and is implemented according to the following steps:

[0011] Step 1: Remove rust, grease, and ash from the corroded and thinned areas on the inner surface of the pressure vessel's connecting pipe.

[0012] Step 2: Prepare a phosphating solution and use a pressure vessel corrosion pit phosphating treatment device to phosphate the corroded and thinned parts of the inner surface of the cylinder after step 1, so as to generate a phosphate conversion film on its surface.

[0013] Step 3: Seal the phosphate conversion membrane from Step 2;

[0014] Step 4: Rinse and dry the phosphate conversion membrane after the sealing treatment in Step 4.

[0015] The first technical solution of this invention is further characterized by:

[0016] The specific process for rust removal described in step 1 is as follows:

[0017] First, mount 80-mesh louvers on an angle grinder. Then, grind the corroded and thinned areas on the inner surface of the pressure vessel's connecting pipe until the metal luster is exposed. Next, manually grind the area step by step with 200-mesh, 400-mesh, and 600-mesh sandpaper until the metal surface of the corroded and thinned areas is smooth. Finally, the dimensionless parameter G0 of the pit after grinding the corroded and thinned areas should not be greater than 0.1. The specific formula for calculating G0 is as follows:

[0018]

[0019] In the formula: G0 is the dimensionless parameter of the pit formed after the corrosion and thinning of the inner surface of the grinding cylinder, C is the depth of the pit formed after the corrosion and thinning of the inner surface of the grinding cylinder, A is the length of the semi-major axis of the pit formed after the corrosion and thinning of the inner surface of the grinding cylinder, T is the pressure vessel wall thickness at the location of the pit, and R is the average radius of the pressure vessel cylinder.

[0020] The specific process of degreasing described in step 1 is as follows:

[0021] Prepare a degreasing solution and spray it evenly onto the corroded and thinned parts of the inner surface of the cylinder after rust removal. After dissolving for at least 10 seconds, wipe the degreasing solution with a clean cloth. The degreasing solution is a mixture of NaOH, Na2SiO3, and CH3COONa. The concentration of NaOH in the degreasing solution is 3g / L-5g / L, the concentration of Na2SiO3 is 16g / L-18g / L, and the concentration of CH3COONa is 14g / L-16g / L. The temperature of the degreasing solution sprayed is 35℃-50℃.

[0022] The ash removal mentioned in step 1 specifically involves using a vacuum cleaner to remove ash from the corroded and thinned parts of the pressure vessel after degreasing.

[0023] The specific process of the phosphating treatment in step 2 is as follows:

[0024] Step 2.1: Prepare the phosphating solution;

[0025] The phosphating solution consists of a main phosphating solution, a phosphating solution accelerator, and an auxiliary film-forming accelerator. The main phosphating solution is a mixture of Zn(H2PO4)2 and ZnO, the phosphating solution accelerator is a mixture of NaF and Zn(NO3)2, and the auxiliary film-forming accelerator is a mixture of Ce(NO3)3 and sodium citrate. The concentrations of Zn(H2PO4)2, ZnO, NaF, Zn(NO3)2, Ce(NO3)3, and sodium citrate in the phosphating solution are 61 g / L, 5 g / L, 2.8 g / L-3.5 g / L, 60 g / L-68 g / L, 0.01 g / L-0.04 g / L, and 1.3 g / L-2.5 g / L.

[0026] To prepare the solution, first put 2L of deionized water into a stainless steel container, then add Zn(H2PO4)2, ZnO, NaF, Zn(NO3)2 and sodium citrate into the stainless steel container in sequence, then add Ce(NO3)3 powder, and stir the solution evenly with a stirring device until the Ce(NO3)3 powder is completely dissolved to obtain the phosphating solution.

[0027] Step 2.2: The phosphating solution from step 2.1 is sprayed onto the corroded and thinned areas on the inner surface of the cylinder using a phosphating treatment device to obtain a phosphate conversion film. The specific process is as follows:

[0028] A constant temperature heating device is set up to maintain the phosphating solution at a constant temperature of 56℃-62℃. The phosphating solution is then sprayed onto the thinned areas of the inner surface of the cylinder through a spray pipe. The phosphating reaction time is 45-50 minutes. The remaining phosphating solution is then completely extracted from the thinned areas through a suction pipe. Finally, a phosphate conversion film forms on the surface of the thinned areas of the inner surface of the cylinder. The thickness of the phosphate conversion film is 9μm-13μm, and the surface resistance of the phosphate conversion film is 3×10⁻⁶. 4 -5×10 4 Ω.

[0029] The specific process of the sealing treatment described in step 3 is as follows:

[0030] Prepare a sealing solution and spray it evenly onto the phosphate conversion membrane. The reaction time is 40-60 seconds. The sealing solution is tartaric acid with a concentration of 25 g / L. The temperature is room temperature and the pH value is 2.

[0031] The specific process for rinsing and drying the phosphate conversion membrane in step 4 is as follows:

[0032] Step 4.1: Spray deionized water evenly onto the phosphate conversion membrane, wipe it clean with a scouring pad, spray deionized water again to clean, and finally wipe it clean with a scouring pad.

[0033] Step 4.2: Dry the phosphate conversion membrane after cleaning in Step 4.1 using a hot air blower.

[0034] The beneficial effects of this invention are:

[0035] The pressure vessel corrosion pit phosphating treatment device of the present invention allows for convenient spraying of a corresponding anti-corrosion coating onto the inner surface of the pressure vessel cylinder through a spray pipe and a liquid extraction pipe.

[0036] The present invention relates to a method for phosphating corrosion pits in pressure vessels. By forming a phosphate conversion film in the corrosion-thinned portion of the inner surface of the cylinder, the bonding force between the phosphate conversion film and the substrate can reach level 0. The film and substrate are firmly bonded and are not easily detached under steam erosion, thus providing long-term and effective protection for the inner surface of the pressure vessel cylinder. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the pressure vessel corrosion pit phosphating treatment device of the present invention.

[0038] In the diagram: 1. Base, 2. Stainless steel container, 3. Constant temperature heating device, 4. Stirring device, 5. Power supply.

[0039] 6. Spray pipes; 601. Phosphating solution nozzles; 602. Spray motors; 603. Spray controllers;

[0040] 7. Liquid extraction pipeline, 701. Phosphating solution suction nozzle, 702. Suction motor, 703. Suction controller. Detailed Implementation

[0041] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0042] The first technical solution provided by this invention is a phosphating treatment device for corrosion pits in pressure vessels, such as... Figure 1 As shown, the device includes a base 1. Inside the base 1, from bottom to top, are a power supply 5 and a constant temperature heating device 3. The power supply 5 provides electricity to the device, and the constant temperature heating device 3 serves to heat and maintain the temperature. Above the constant temperature heating device 3, a stainless steel container 2 for phosphating solution is installed. The stainless steel container 2 serves as a container for various solutions related to phosphating treatment. Inside the stainless steel container 2, a stirring device 4 is installed to stir the solution inside the stainless steel container 2 evenly. Both the constant temperature heating device 3 and the stirring device 4 are connected to the power supply 5. The bottom of the stainless steel container 2 also... The device is connected to a spray pipe 6 and a liquid extraction pipe 7. The spray pipe 6 can extend into the cylinder of the pressure vessel to spray the phosphating solution. At the same time, it can spray the corrosion pits in the corrosion-thinned areas multiple times. The operation is simple, convenient and quick. The liquid extraction pipe 7 can suck up the excess phosphating solution in the corrosion-thinned areas on the inner surface of the cylinder, saving phosphating solution. The spray pipe 6 and the liquid extraction pipe 7 make it easy to spray the corresponding anti-corrosion coating on the inner surface of the pressure vessel cylinder, solving the problem that it is very difficult to carry out anti-corrosion treatment on the inner surface of the pressure vessel cylinder using conventional spraying equipment.

[0043] One end of the spray pipe 6 is connected to the bottom of the stainless steel container 2 containing the phosphating solution, and the other end of the spray pipe 6 is equipped with a phosphating solution nozzle 601. A spray motor 602 and a spray controller 603 are also installed on the pipe body of the spray pipe 6. The spray controller 603 can control the on / off state of the spray pipe 6, and the spray motor 602 provides power for the spray pipe 6 to spray the phosphating solution. One end of the extraction pipe 7 is connected to the bottom of the stainless steel container 2 containing the phosphating solution, and the other end of the extraction pipe 7 is equipped with a phosphating solution suction nozzle 701. A suction motor 702 and a suction controller 703 are also installed on the pipe body of the extraction pipe 7. The suction controller 703 can control the on / off state of the extraction pipe 7, and the suction motor 702 provides power for the extraction pipe 7 to suction the phosphating solution.

[0044] The phosphating solution nozzle 601 is made of stainless steel, while the phosphating solution suction nozzle 701 is made of silicone. The diameter of the phosphating solution suction nozzle 701 is twice that of the phosphating solution nozzle 601 to ensure that the sprayed phosphating solution can be completely sucked up.

[0045] The second technical solution provided by this invention is a phosphating treatment method for corrosion pits in pressure vessels, which uses the aforementioned phosphating treatment device for corrosion pits in pressure vessels and is implemented according to the following steps:

[0046] Step 1: Remove rust, grease, and ash from the corroded and thinned areas on the inner surface of the pressure vessel's connecting pipe.

[0047] The specific process for rust removal in step 1 is as follows:

[0048] First, mount 80-mesh louvers on an angle grinder. Then, grind the thinned area on the inner surface of the cylinder due to corrosion until the thinned area reveals a metallic luster. Next, manually grind the area step by step with 200-mesh, 400-mesh, and 600-mesh sandpaper until the metal surface of the thinned area is smooth. Finally, the dimensionless parameter G0 of the pit after grinding the thinned area should not be greater than 0.1. The specific formula for calculating G0 is as follows:

[0049]

[0050] In the formula: G0 is the dimensionless parameter of the pit formed after the corrosion and thinning of the inner surface of the grinding cylinder, C is the depth of the pit formed after the corrosion and thinning of the inner surface of the grinding cylinder, A is the length of the semi-major axis of the pit formed after the corrosion and thinning of the inner surface of the grinding cylinder, T is the pressure vessel wall thickness at the location of the pit, and R is the average radius of the pressure vessel cylinder.

[0051] The specific process of degreasing in step 1 is as follows:

[0052] Prepare a degreasing solution and spray it evenly onto the corroded and thinned parts of the inner surface of the cylinder after rust removal treatment. Dissolve for a certain period of time, with a dissolution time of at least 10 seconds. Wipe the degreasing solution with a clean cloth. The degreasing solution is a mixture of NaOH, Na2SiO3, and CH3COONa. The concentration of NaOH in the degreasing solution is 3g / L-5g / L, the concentration of Na2SiO3 is 16g / L-18g / L, and the concentration of CH3COONa is 14g / L-16g / L. The temperature of the degreasing solution sprayed is 35℃-50℃.

[0053] In step 1, the ash removal process specifically involves using a vacuum cleaner to remove ash from the corroded and thinned areas on the inner surface of the cylinder after degreasing.

[0054] Step 2: Prepare a phosphating solution and use a pressure vessel corrosion pit phosphating treatment device to phosphate the corroded and thinned parts of the inner surface of the cylinder after step 1, so as to generate a phosphate conversion film on its surface.

[0055] The specific process of phosphating in step 2 is as follows:

[0056] Step 2.1: Prepare the phosphating solution;

[0057] The phosphating solution consists of a main phosphating solution, a phosphating solution promoter, and an auxiliary film-forming promoter. The main phosphating solution is a mixture of Zn(H₂PO₄)₂ and ZnO, which is stable and promotes dense nucleation during the reaction. The phosphating solution promoter is a mixture of NaF and Zn(NO₃)₂; the rare earth element increases the density of the phosphating film. The auxiliary film-forming promoter is Ce(NO₃)₃ and sodium citrate. Ce(NO₃)₃ has a stable structure and good coupling with the main phosphating solution. During phosphating, Ce compounds adsorb onto crystal defects in the phosphating film substrate, increasing the nucleation activity of the main phosphating solution on the inner surface of the container and promoting the initial nucleation rate and density of the film. Furthermore, adding an appropriate amount of sodium citrate to the phosphating solution not only promotes the crystallization rate of phosphates but also forms more soluble complexes, assisting Ce(NO₃)₃ in improving the nucleation rate and the density of the phosphating film.

[0058] The concentrations of Zn(H2PO4)2 in the phosphating solution were 61 g / L, ZnO was 5 g / L, NaF was 2.8 g / L-3.5 g / L, Zn(NO3)2 was 60 g / L-68 g / L, Ce(NO3)3 was 0.01 g / L-0.04 g / L, and sodium citrate was 1.3 g / L-2.5 g / L.

[0059] During preparation, first take 2L of deionized water into stainless steel container 2, then add Zn(H2PO4)2, ZnO, NaF, Zn(NO3)2 and sodium citrate into the phosphating solution stainless steel container 2 in sequence, then add Ce(NO3)3 powder, and stir the solution evenly with stirring device 4 until Ce(NO3)3 powder is completely dissolved to obtain phosphating solution;

[0060] Step 2.2: The phosphating solution from step 2.1 is sprayed onto the corroded and thinned areas on the inner surface of the cylinder using a phosphating treatment device to obtain a phosphate conversion film. The specific process is as follows:

[0061] A constant temperature heating device 3 is set up to maintain the temperature of the phosphating solution at a constant 56℃-62℃. The phosphating solution is then sprayed onto the corrosion-thinned areas on the inner surface of the cylinder through spray pipe 6. The phosphating reaction time is 45-50 minutes. The remaining phosphating solution is then completely extracted from the corrosion-thinned areas on the inner surface of the cylinder through extraction pipe 7. Finally, a phosphate conversion film is formed on the surface of the corrosion-thinned areas on the inner surface of the cylinder. The thickness of the phosphate conversion film is 9μm-13μm, and the surface resistance of the phosphate conversion film is 3×10⁻⁶. 4 -5×10 4 Ω.

[0062] Phosphating treatment on the corroded and thinned areas of the inner surface of the pressure vessel cylinder yielded a 9μm-13μm crystalline phosphate conversion film. The phosphate conversion film exhibited clean, burr-free mesh edges with no peeling or flaking. The adhesion between the phosphate conversion film and the substrate reached level 0, demonstrating a strong bond that resists detachment under steam erosion. This provides long-term, effective protection for the inner surface of the pressure vessel cylinder. Furthermore, the surface impedance of the phosphate conversion film was 3×10⁻⁶. 4 -5×10 4 Ω can effectively prevent the diffusion of corrosion ions, thereby enhancing the corrosion resistance of the thinned areas and reducing the corrosion rate.

[0063] Step 3: Seal the phosphate conversion membrane from Step 2;

[0064] The specific process of sealing the holes in step 3 is as follows:

[0065] Prepare a sealing solution and spray it evenly onto the phosphate conversion membrane. The reaction time is 40-60 seconds. The sealing solution is tartaric acid with a concentration of 25 g / L. The temperature is room temperature and the pH value is 2.

[0066] Step 4: Rinse and dry the phosphate conversion membrane after the sealing treatment in Step 4;

[0067] The specific process for rinsing and drying the phosphate conversion membrane in step 4 is as follows:

[0068] Step 4.1: Spray deionized water evenly onto the phosphate conversion membrane, wipe it clean with a scouring pad, spray deionized water again to clean it, and finally wipe it clean with a scouring pad.

[0069] Step 4.2: Dry the phosphate conversion membrane after cleaning in Step 4.1 using a hot air blower.

[0070] Specific embodiments of the present invention are as follows:

[0071] Example 1

[0072] The pressure vessel corrosion pit phosphating treatment device includes a base 1. Inside the base 1, from bottom to top, there are a power supply 5 and a constant temperature heating device 3. Above the constant temperature heating device 3, there is a stainless steel container 2 for phosphating liquid. Inside the stainless steel container 2, there is a stirring device 4. Both the constant temperature heating device 3 and the stirring device 4 are connected to the power supply 5. The bottom of the stainless steel container 2 is also connected to a spray pipe 6 and a liquid extraction pipe 7.

[0073] Example 2

[0074] The pressure vessel corrosion pit phosphating treatment device includes a base 1. Inside the base 1, from bottom to top, there are a power supply 5 and a constant temperature heating device 3. Above the constant temperature heating device 3, there is a stainless steel container 2 for phosphating liquid. Inside the stainless steel container 2, there is a stirring device 4. Both the constant temperature heating device 3 and the stirring device 4 are connected to the power supply 5. The bottom of the stainless steel container 2 is also connected to a spray pipe 6 and a liquid extraction pipe 7.

[0075] One end of the spray pipe 6 is connected to the bottom of the stainless steel container 2 containing phosphating solution, and the other end of the spray pipe 6 is equipped with a phosphating solution nozzle 601. The spray pipe 6 is also equipped with a spray motor 602 and a spray controller 603. One end of the liquid extraction pipe 7 is connected to the bottom of the stainless steel container 2 containing phosphating solution, and the other end of the liquid extraction pipe 7 is equipped with a phosphating solution suction nozzle 701. The liquid extraction pipe 7 is also equipped with a suction motor 702 and a liquid extraction controller 703.

[0076] The phosphating solution nozzle 601 is made of stainless steel, and the phosphating solution suction nozzle 701 is made of silicone. The diameter of the suction nozzle 701 is twice that of the phosphating solution nozzle 601.

[0077] Example 3

[0078] The method for phosphating corrosion pits in pressure vessels, using the pressure vessel corrosion pit phosphating treatment device described in Example 1 or Example 2 above, is implemented according to the following steps:

[0079] Step 1: Remove rust, grease, and ash from the corroded and thinned areas on the inner surface of the pressure vessel's connecting pipe.

[0080] The specific process of rust removal described in step 1 is as follows: First, install 80-mesh louvers on an angle grinder, and then grind the corroded and thinned parts on the inner surface of the cylinder until the corroded and thinned parts on the inner surface of the cylinder show a metallic luster. Then, use 200-mesh, 400-mesh, and 600-mesh sandpaper to manually grind the metal surface of the corroded and thinned parts on the inner surface of the cylinder in turn, so that the metal surface of the corroded and thinned parts on the inner surface of the cylinder is smooth. Finally, the dimensionless parameter of the pit after grinding the corroded and thinned parts on the inner surface of the cylinder is 0.009.

[0081] The specific process of degreasing described in step 1 is as follows:

[0082] Prepare a degreasing solution and spray it evenly onto the corroded and thinned parts of the inner surface of the cylinder after rust removal treatment. After dissolving for 10 seconds, wipe the degreasing solution with a clean cloth. The degreasing solution is a mixture of NaOH, Na2SiO3, and CH3COONa. The concentration of NaOH in the degreasing solution is 3.5 g / L, the concentration of Na2SiO3 is 17 g / L, and the concentration of CH3COONa is 15 g / L. The temperature of the degreasing solution sprayed is 40℃.

[0083] The ash removal mentioned in step 1 specifically involves using a vacuum cleaner to remove ash from the corroded and thinned areas on the inner surface of the cylinder after degreasing.

[0084] Step 2: Prepare a phosphating solution and use a pressure vessel corrosion pit phosphating treatment device to phosphate the corroded and thinned parts of the inner surface of the cylinder after step 1, so as to generate a phosphate conversion film on its surface.

[0085] The specific process of the phosphating treatment in step 2 is as follows:

[0086] Step 2.1: Prepare the phosphating solution;

[0087] In this case, the concentrations of each component in the phosphating solution are as follows: Zn(H2PO4)2 is 61 g / L, ZnO is 5 g / L, NaF is 3.2 g / L, Zn(NO3)2 is 65 g / L, Ce(NO3)3 is 0.003 g / L, and sodium citrate is 1.9 g / L.

[0088] During preparation, first take 2L of deionized water into stainless steel container 2, then add Zn(H2PO4)2, ZnO, NaF, Zn(NO3)2, and sodium citrate to the phosphating solution in the stainless steel container 2 according to the concentrations in this case, and then add 0.06g of Ce(NO3)3 powder. Stir the solution evenly using stirring device 4 until the Ce(NO3)3 powder is completely dissolved to obtain the phosphating solution.

[0089] Step 2.2: The phosphating solution from step 2.1 is sprayed onto the corroded and thinned areas on the inner surface of the cylinder using a phosphating treatment device to obtain a phosphate conversion film. The specific process is as follows:

[0090] A constant-temperature heating device 3 is set up to maintain the temperature of the phosphating solution at a constant 60℃. The phosphating solution is then sprayed onto the thinned areas of the inner surface of the cylinder through a spray pipe 6. The phosphating reaction time is 45 minutes. The remaining phosphating solution is then completely extracted from the thinned areas of the inner surface of the cylinder through a suction pipe 7. Finally, a phosphate conversion film is formed on the surface of the thinned areas of the inner surface of the cylinder. The thickness of the phosphate conversion film is 9.7 μm-10.5 μm, and the surface resistance of the phosphate conversion film is 3.024 × 10⁻⁶. 4 Ω.

[0091] Step 3: Seal the phosphate conversion membrane from Step 2;

[0092] The specific process of the sealing treatment described in step 3 is as follows:

[0093] Prepare a sealing solution and spray it evenly onto the phosphate conversion membrane. The reaction time is 40 seconds. The sealing solution is tartaric acid with a concentration of 25 g / L. The temperature is room temperature and the pH value is 2.

[0094] Step 4: Rinse and dry the phosphate conversion membrane after the sealing treatment in Step 4;

[0095] The specific process for rinsing and drying the phosphate conversion membrane in step 4 is as follows:

[0096] Step 4.1: Spray deionized water evenly onto the phosphate conversion membrane, wipe it clean with a scouring pad, spray deionized water again to clean it, and finally wipe it clean with a scouring pad.

[0097] Step 4.2: Dry the phosphate conversion membrane after cleaning in Step 4.1 using a hot air blower.

[0098] Example 4

[0099] The method for phosphating corrosion pits in pressure vessels, using the pressure vessel corrosion pit phosphating treatment device described in Example 1 or Example 2 above, is as follows:

[0100] The only difference between Example 4 and Example 3 above is that the concentration of NaOH in the grease solution used in Example 4 is 3 g / L, the concentration of Na2SiO3 is 16 g / L, the concentration of CH3COONa is 14 g / L, and the temperature of the sprayed degreasing solution is 50°C.

[0101] The phosphating solution used had the following concentrations: Zn(H2PO4)2 61 g / L, ZnO 5 g / L, NaF 3.5 g / L, Zn(NO3)2 67 g / L, Ce(NO3)3 0.002 g / L, and sodium citrate 2.2 g / L. The phosphating solution was kept at a constant temperature of 62 °C, and the phosphating reaction time was 50 min.

[0102] The reaction time for the sealing solution is 60 seconds.

[0103] The thickness of the phosphate conversion membrane ranges from 10.7 μm to 12.2 μm, and its surface impedance is 4.376 × 10⁻⁶. 4 Ω.

[0104] As demonstrated in Examples 3 and 4 above, after phosphating the corroded and thinned areas on the inner surface of the pressure vessel using a pressure vessel corrosion pit phosphating treatment device, a crystalline phosphate conversion film is obtained. The thickness of the film is within 9μm-13μm. Furthermore, the phosphate conversion film has neatly cut edges, no peeling, and no burrs. The adhesion between the phosphate conversion film and the substrate reaches level 0, indicating a strong bond that is not easily detached under steam erosion. This provides long-term effective protection for the inner surface of the pressure vessel. The surface resistance of the phosphate conversion film is 3×10⁻⁶. 4 Ω-5×10 4 Ω can effectively prevent the diffusion of corrosive ions, thereby enhancing the corrosion resistance of the thinned areas and greatly reducing the corrosion rate.

Claims

1. A phosphate treatment device for corrosion pits in pressure vessels, characterized in that, Includes a base (1), inside which a power supply (5) and a constant temperature heating device (3) are arranged from bottom to top. A phosphating liquid stainless steel container (2) is installed above the constant temperature heating device (3). A stirring device (4) is arranged inside the phosphating liquid stainless steel container (2). Both the constant temperature heating device (3) and the stirring device (4) are connected to the power supply (5). A spray pipe (6) and a liquid extraction pipe (7) are also connected to the bottom of the phosphating liquid stainless steel container (2). One end of the spray pipe (6) is connected to the bottom of the stainless steel container (2) of phosphating solution, and the other end of the spray pipe (6) is provided with a phosphating solution nozzle (601). The spray pipe (6) is also provided with a spray motor (602) and a spray controller (603). One end of the liquid extraction pipe (7) is connected to the bottom of the stainless steel container (2) of phosphating solution, and the other end of the liquid extraction pipe (7) is provided with a phosphating solution suction nozzle (701). The liquid extraction pipe (7) is also provided with a suction motor (702) and a suction controller (703). The phosphating liquid nozzle (601) is made of stainless steel, the phosphating liquid suction nozzle (701) is made of silicone, and the diameter of the suction nozzle (701) is twice the diameter of the phosphating liquid nozzle (601).

2. A method for phosphating corrosion pits in pressure vessels, characterized in that, The pressure vessel corrosion pit phosphating treatment device described in claim 1 is implemented according to the following steps: Step 1: Remove rust, grease, and ash from the corroded and thinned areas on the inner surface of the pressure vessel's connecting pipe. Step 2: Prepare a phosphating solution and use a pressure vessel corrosion pit phosphating treatment device to phosphate the corroded and thinned parts of the inner surface of the cylinder after step 1, so as to generate a phosphate conversion film on its surface. The specific process of the phosphating treatment in step 2 is as follows: Step 2.1: Prepare the phosphating solution; The phosphating solution consists of a main phosphating solution, a phosphating solution accelerator, and an auxiliary film-forming accelerator. The main phosphating solution comprises... It is a mixture of ZnO and phosphating solution accelerator composed of NaF and The mixture contains film-forming aids specifically: It is mixed with sodium citrate and used in phosphating treatment solutions. The concentration of [unspecified substance] was 61 g / L, the concentration of ZnO was 5 g / L, and the concentration of NaF was 2.8 g / L-3.5 g / L. The concentration is 60g / L-68g / L. The concentration of [specific substance] is 0.01 g / L-0.04 g / L, and the concentration of sodium citrate is 1.3 g / L-2.5 g / L; When preparing the solution, first take 2L of deionized water into a stainless steel container (2), then... ZnO, NaF Sodium citrate was added sequentially to stainless steel container (2), and then... The powder is stirred evenly in a solution using a stirring device (4) until... The powder is completely dissolved to obtain a phosphating solution; Step 2.2: The phosphating solution from step 2.1 is sprayed onto the corroded and thinned areas on the inner surface of the cylinder using a phosphating treatment device to obtain a phosphate conversion film. The specific process is as follows: A constant temperature heating device (3) is set up to keep the phosphating solution at a constant temperature of 56℃-62℃. Then, the phosphating solution is sprayed onto the corrosion-thinned part of the inner surface of the cylinder through the spray pipe (6). The phosphating reaction time is 45min-50min. Then, the phosphating solution on the corrosion-thinned part of the inner surface of the cylinder is completely sucked out through the liquid extraction pipe (7). Finally, a phosphate conversion film is formed on the surface of the corrosion-thinned part of the inner surface of the cylinder. The thickness of the phosphate conversion film is 9μm-13μm, and the surface resistance of the phosphate conversion film is 3× -5× Ω; Step 3: Seal the phosphate conversion membrane from Step 2; Step 4: Rinse and dry the phosphate conversion membrane after the sealing treatment in Step 4.

3. The phosphating treatment method for corrosion pits in pressure vessels according to claim 2, characterized in that, The specific process for rust removal described in step 1 is as follows: First, mount 80-mesh louvers on an angle grinder. Then, grind the thinned area of ​​corrosion on the inner surface of the pressure vessel's inner cylinder until the metal luster is exposed. Next, manually grind the area step by step with 200-mesh, 400-mesh, and 600-mesh sandpaper until the metal surface of the thinned area is smooth. Finally, the pits left after grinding the thinned area should have dimensionless parameters. It should not be greater than 0.1, where The specific calculation formula is as follows: （1） In the formula: is a dimensionless parameter for the pit formed after the corrosion and thinning of the inner surface of the grinding cylinder, C is the depth of the pit formed after the corrosion and thinning of the inner surface of the grinding cylinder, A is the length of the semi-major axis of the pit formed after the corrosion and thinning of the inner surface of the grinding cylinder, T is the pressure vessel wall thickness at the location of the pit, and R is the average radius of the pressure vessel cylinder.

4. The method for phosphating corrosion pits in pressure vessels according to claim 2, characterized in that, The specific process of degreasing described in step 1 is as follows: Prepare a degreasing solution and spray it evenly onto the corroded and thinned areas of the inner surface of the cylinder after rust removal. Allow it to dissolve for at least 10 seconds, then wipe off the degreasing solution with a clean cloth. The degreasing solution consists of NaOH, ... , It is a mixture, except that the concentration of NaOH in the oil solution is 3g / L-5g / L. The concentration is 16g / L-18g / L. The concentration is 14g / L-16g / L, and the temperature of the degreasing solution applied by spraying is 35℃-50℃; The ash removal method described in step 1 specifically involves using a vacuum cleaner to remove ash from the corroded and thinned parts of the pressure vessel after degreasing.

5. The method for phosphating corrosion pits in pressure vessels according to claim 2, characterized in that, The specific process of the sealing treatment described in step 3 is as follows: Prepare a sealing solution and spray it evenly onto the phosphate conversion membrane. The reaction time is 40-60 seconds. The sealing solution is tartaric acid with a concentration of 25 g / L. The temperature is room temperature and the pH value is 2.

6. The method for phosphating corrosion pits in pressure vessels according to claim 2, characterized in that, The specific process for rinsing and drying the phosphate conversion membrane in step 4 is as follows: Step 4.1: Spray deionized water evenly onto the phosphate conversion membrane, wipe it clean with a scouring pad, spray deionized water again to clean, and finally wipe it clean with a scouring pad. Step 4.2: Dry the phosphate conversion membrane after cleaning in Step 4.1 using a hot air blower.

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