Pickling treatment equipment for stainless steel pipe production

Abstract

The invention provides pickling treatment equipment for stainless steel pipe making. The pickling treatment equipment comprises a plasma pretreatment system, a fluoride-free electrolytic pickling system and a waste liquid closed-loop regeneration system. The plasma pretreatment system comprises a plasma generator, the plasma generator is driven by a radio frequency power supply, the plasma pretreatment system further comprises a cylindrical reaction cavity, a stainless steel tube is contained in the reaction cavity, and a plurality of groups of annular copper electrodes are arranged in the reaction cavity. The multiple sets of annular copper electrodes are distributed at equal intervals in the axial direction of the reaction cavity, the stainless steel pipe serves as a grounding electrode to penetrate through the multiple sets of annular copper electrodes, the plasma generator bombards the surface of the stainless steel pipe through low-temperature plasma, and an oxide layer is loosened.

Description

Technical Field

[0001] The invention relates to the technical field of metal surface treatment, in particular to a pickling treatment device for stainless steel pipes. Background Art

[0002] The pickling equipment for stainless steel pipes is used for pickling of stainless steel pipes. Pickling is a typical chemical surface treatment process. Pickling is mainly used to remove the oxide layer, welding slag and impurities on the surface of stainless steel, and improve the surface finish and corrosion resistance of stainless steel pipes.

[0003] Traditional pickling equipment usually includes the following processes. First, the pretreatment process, first remove the oil and organic matter on the surface of the stainless steel pipe through alkaline solution or ultrasonic cleaning. Then mechanical pretreatment is performed to remove the thick oxide layer on the surface of the stainless steel pipe to reduce the burden of subsequent pickling. Second, the pickling process, the prepared acid solution is circulated through a pump to maintain a uniform concentration, and the heating system maintains the acid temperature, and the stainless steel pipe is pickled under this condition. Third, the post-treatment process, the stainless steel pipe is washed with water, and the residual acid is removed by countercurrent water washing. Then it is neutralized with an alkaline solution and passivated with nitric acid to form a protective oxide film. It is then dried with hot air. Fourth, the waste liquid treatment process, the acidic wastewater is treated in a neutralization tank to recover metal ions.

[0004] However, traditional pickling equipment still has shortcomings in terms of environmental protection, efficiency and intelligence, which are specifically reflected in the following points: First, HF acid mist is very harmful, and the wastewater contains heavy metals and fluoride ions, which has high treatment costs. Second, the pickling time is long and the energy consumption is high (heating, circulating pump). Third, there is a lot of manual intervention and parameter adjustment depends on experience. Summary of the invention

[0005] The present invention aims to solve the above technical problems and provides a pickling treatment device for stainless steel pipes.

[0006] The technical solution of the present invention is a pickling treatment device for stainless steel pipes, comprising a plasma pretreatment system, a fluorine-free electrolytic pickling system, and a waste liquid closed-loop regeneration system;

[0007] The plasma pretreatment system comprises a plasma generator driven by a radio frequency power supply, and further comprises a cylindrical reaction chamber, wherein the reaction chamber is used to accommodate a stainless steel tube, and a plurality of groups of annular copper electrodes are arranged in the reaction chamber, and the plurality of groups of annular copper electrodes are equidistantly distributed along the axial direction of the reaction chamber, and the stainless steel tube passes through the plurality of groups of annular copper electrodes as a grounding electrode, and the plasma generator bombards the surface of the stainless steel tube with low-temperature plasma to loosen the oxide layer;

[0008] The fluorine-free electrolytic pickling system comprises a composite tank, the electrolyte in the composite tank is a neutral salt solution, a titanium alloy mesh cathode is arranged in the composite tank, the titanium alloy mesh cathode surrounds the outer wall of the stainless steel tube as the anode, and the inter-electrode distance is 5-10 mm, the composite tank is equipped with a pulse power supply connecting the two electrodes, the pulse power supply supplies power for the electrochemical reaction in the composite tank, and an ultrasonic transducer is arranged in the composite tank, the ultrasonic transducer destroys the oxide layer passivation film on the surface of the stainless steel tube through ultrasonic cavitation to accelerate the penetration of the electrolyte;

[0009] The waste liquid closed-loop regeneration system comprises a diffusion dialysis membrane assembly, the diffusion dialysis membrane assembly comprises a waste liquid flow channel and a recovery liquid flow channel forming a branch, a plate-frame membrane stack is provided at a common front end of the waste liquid flow channel and the recovery liquid flow channel, the recovery liquid flow channel is connected to the composite tank, the waste liquid closed-loop regeneration system also comprises a primary sedimentation tank and a secondary sedimentation tank arranged after the primary sedimentation tank, the waste liquid flow channel is connected to the primary sedimentation tank, a dosing device for adding calcium salt is provided in the primary sedimentation tank, and an adsorbent is provided in the secondary sedimentation tank;

[0010] The system also includes a control system, which includes a plurality of laser confocal sensors arranged in the plasma pretreatment system and the fluorine-free electrolytic pickling system, and dynamically adjusts the current of the radio frequency power supply, the current of the pulse power supply, and the power of the ultrasonic transducer according to the feedback of the laser confocal sensors. The control system also includes an online plasma spectrometer arranged at the common front end of the waste liquid flow channel and the recovered liquid flow channel, and automatically adjusts the dialysate flow of the diffusion dialysis membrane assembly according to the feedback of the online plasma spectrometer.

[0011] As an embodiment, the inner wall of the reaction chamber is made of stainless steel and is coated with an alumina ceramic coating. The chamber diameter of the reaction chamber is 500 mm, the chamber length of the reaction chamber is 6 m, one end of the reaction chamber is sealed by a sealing plate with an electrode connector, and the other end of the reaction chamber is sealed by an O-ring and a quick-release flange.

[0012] As an implementation mode, one end of the stainless steel tube is fixed to the electrode joint, an insulating joint is provided on the quick-release flange, the insulating joint is coaxial with the electrode joint, and the other end of the stainless steel tube is fixed to the insulating joint.

[0013] As an implementation manner, the frequency of the alternating electric field provided by the radio frequency power supply is 13.56 MHz, and the power of the radio frequency power supply is adjusted within the range of 1 to 5 kW according to different diameters of the stainless steel pipe.

[0014] As an embodiment, the surface of the annular copper electrode is plated with nickel.

[0015] As an embodiment, the composite tank includes an alloy lining and a PP outer shell.

[0016] As an implementation method, the pulse frequency of the pulse power supply is 100-500 Hz, the duty cycle is 10%-30%, and the peak current density is 3-5 A / dm 2 .

[0017] As an embodiment, the plate-and-frame membrane stack is formed by alternatingly stacking anion exchange membranes and acid-resistant flow channel baffles. The membrane material of the anion exchange membrane is a perfluorosulfonic acid ion exchange membrane with a thickness of 0.15 to 0.2 mm, a temperature resistance of ≤60°C, and a pH tolerance range of 0 to 14.

[0018] As an implementation mode, a stirring device is provided in the primary sedimentation tank, and the dosing device is used to add calcium bicarbonate slurry to the primary sedimentation tank.

[0019] As an embodiment, the adsorbent is modified nano-hydroxyapatite with a specific surface area of ​​≥200m 2 / g, fluorine adsorption capacity ≥20mg / g.

[0020] Compared with the prior art, the beneficial effect of the present invention is that the pickling treatment equipment for the stainless steel pipe uses a plasma generator in the pretreatment process, which provides the core energy source. In the closed cylindrical reaction chamber, low-temperature plasma activates the surface of the stainless steel pipe to loosen its oxide layer. The unique electrode configuration mode, that is, the stainless steel pipe itself is used as the grounding electrode, passing through multiple groups of equidistantly distributed annular copper electrodes, so that the surface of the stainless steel pipe is fully and evenly treated. After this process, the difficulty of subsequent pickling is reduced, and the amount of acid used for subsequent pickling is reduced by more than 50%. In the pickling treatment process, a neutral salt electrolyte is used to replace the original pickling medium, and the oxide layer is stripped by electrochemical reaction to avoid the use of strong acid. The unique electrode configuration mode, that is, the titanium alloy mesh cathode surrounds the outer wall of the stainless steel pipe, and the distance between the electrodes is 5 to 10 mm, so that the current density reaches 0.5 to 1.5A / dm 2, the surface roughness of the stainless steel pipe obtained after pickling is Ra≤0.2μm, which is much better than the traditional pickling process. In addition, the ultrasonic cavitation effect of the ultrasonic transducer accelerates the penetration of the acid solution, and the pickling time is shortened by more than 30%. After this process, the discharged wastewater does not contain fluorine, and the recovery rate of metal ions is ≥95%. In the waste liquid treatment process, the branched waste liquid flow channel and the recovered liquid flow channel are respectively used for the flow of the original liquid after dialysis and the dialysate, and the two flow in opposite directions. After the original liquid passes through the plate and frame membrane stack, the dialysate returns to the composite tank, and the rest enters the primary sedimentation tank and the secondary sedimentation tank. Therefore, the waste liquid closed-loop regeneration system forms a closed-loop control through the three-level treatment of membrane separation, chemical precipitation, and adsorption, realizing the efficient recycling of acid and the deep removal of fluoride ions. Compared with the traditional neutralization and discharge process, the acid consumption is reduced, the amount of hazardous waste is reduced, and the operating cost is reduced. In the above three processes, the control system is deeply involved in the control, that is, through the real-time detection of the laser confocal sensor and the plasma spectrometer, the corresponding working parameters are dynamically adjusted, which greatly reduces the frequency of manual intervention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A functional block diagram of a pickling treatment device for stainless steel pipes provided in an embodiment of the present invention;

[0022] Figure 2 A schematic diagram of the structure of a cylindrical reaction chamber provided in an embodiment of the present invention;

[0023] Figure 3 A schematic structural diagram of a titanium alloy mesh cathode provided in an embodiment of the present invention.

[0024] In the figure: 1. reaction chamber; 2. stainless steel tube; 3. annular copper electrode; 4. electrode joint; 5. sealing plate; 6. O-ring; 7. quick-release flange; 8. insulating joint; 9. titanium alloy mesh cathode. DETAILED DESCRIPTION

[0025] The above and other embodiments and advantages of the present invention are described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments.

[0026] In one embodiment, Figures 1 to 3 shown.

[0027] The present embodiment provides a pickling treatment device for stainless steel pipe, which includes a plasma pretreatment system, a fluorine-free electrolytic pickling system, and a waste liquid closed-loop regeneration system; the plasma pretreatment system includes a plasma generator, which is driven by a radio frequency power supply, and the plasma pretreatment system also includes a cylindrical reaction chamber 1, the reaction chamber 1 is for accommodating a stainless steel pipe 2, and a plurality of groups of annular copper electrodes 3 are arranged in the reaction chamber 1, and the plurality of groups of annular copper electrodes 3 are equidistantly distributed along the axial direction of the reaction chamber 1, and the stainless steel pipe 2 passes through the plurality of groups of annular copper electrodes 3 as a grounding electrode, and the plasma generator uses low-temperature plasma to bombard the surface of the stainless steel pipe 2 to loosen the oxide layer; the fluorine-free electrolytic pickling system includes a composite tank, the electrolyte in the composite tank is a neutral salt solution, a titanium alloy mesh cathode 9 is arranged in the composite tank, the titanium alloy mesh cathode 9 surrounds the outer wall of the stainless steel pipe 2 as an anode, and the inter-electrode spacing is 5 to 10 mm, the composite tank is equipped with a pulse power supply connecting the two poles, the pulse power supply is powered for the electrochemical reaction in the composite tank, and an ultrasonic transducer is arranged in the composite tank, and the ultrasonic transducer passes The passivation film of the oxide layer on the surface of the stainless steel pipe 2 is destroyed by ultrasonic cavitation to accelerate the penetration of the electrolyte; the waste liquid closed-loop regeneration system includes a diffusion dialysis membrane assembly, the diffusion dialysis membrane assembly includes a waste liquid flow channel and a recovery liquid flow channel forming a branch, a plate-frame membrane stack is provided at the common front end of the waste liquid flow channel and the recovery liquid flow channel, and the recovery liquid flow channel is connected to the composite tank. The waste liquid closed-loop regeneration system also includes a primary sedimentation tank and a secondary sedimentation tank arranged after the primary sedimentation tank, the waste liquid flow channel is connected to the primary sedimentation tank, a dosing device for calcium salt addition is provided in the primary sedimentation tank, and an adsorbent is provided in the secondary sedimentation tank; and also includes a control system, the control system includes a plurality of laser confocal sensors provided in the plasma pretreatment system and the fluorine-free electrolytic pickling system, and according to the feedback of the laser confocal sensor, the current of the radio frequency power supply, the current of the pulse power supply, and the power of the ultrasonic transducer are dynamically adjusted, the control system also includes an online plasma spectrometer provided at the common front end of the waste liquid flow channel and the recovery liquid flow channel, and according to the feedback of the online plasma spectrometer, the dialysate flow rate of the diffusion dialysis membrane assembly is automatically adjusted.

[0028] In this embodiment, the pickling treatment equipment for the stainless steel pipe 2 is an integrated stainless steel pipe 2 pickling treatment system, which integrates three core modules: plasma pretreatment, fluorine-free electrolytic pickling, and closed-loop regeneration of waste liquid, and realizes efficient, environmentally friendly, and low-consumption surface treatment through intelligent control. The equipment is suitable for stainless steel pipes 2 such as 304, 316L, and duplex steel, and can process pipe diameters ranging from Φ20 to 200 mm, with a processing speed of 3 to 5 meters per minute, a surface roughness of Ra ≤ 0.2 μm, an acid recovery rate of ≥ 85%, and a fluoride ion removal rate of ≥ 99.5%. Specifically, in the pretreatment process, a plasma generator is used to provide a core energy source. In a closed cylindrical reaction chamber 1, a low-temperature plasma activates the surface of the stainless steel pipe 2 to loosen its oxide layer. The unique electrode configuration mode, that is, the stainless steel pipe 2 itself is used as a grounding electrode, passes through multiple groups of equally spaced annular copper electrodes 3, so that the surface of the stainless steel pipe 2 is fully and evenly treated. After this process, the difficulty of subsequent pickling is reduced, and the amount of acid used for subsequent pickling is reduced by more than 50%. In the pickling process, neutral salt electrolyte is used to replace the original pickling medium, and the oxide layer is stripped by electrochemical reaction, avoiding the use of strong acid. The unique electrode configuration, that is, the titanium alloy mesh cathode 9 surrounds the outer wall of the stainless steel tube 2, and the distance between the electrodes is 5 to 10 mm, so that the current density reaches 0.5 to 1.5A / dm 2 , the surface roughness of the stainless steel pipe 2 obtained after pickling is Ra≤0.2μm, which is much better than the traditional pickling process. In addition, the penetration of the acid solution is accelerated under the ultrasonic cavitation effect of the ultrasonic transducer, and the pickling time is shortened by more than 30%. After this process, the discharged wastewater does not contain fluorine, and the recovery rate of metal ions is ≥95%. In the waste liquid treatment process, the branched waste liquid flow channel and the recovered liquid flow channel are respectively used for the flow of the original liquid after dialysis and the dialysate, and the two flow in opposite directions. After the original liquid passes through the plate and frame membrane stack, the dialysate returns to the composite tank, and the rest enters the primary sedimentation tank and the secondary sedimentation tank. Therefore, the waste liquid closed-loop regeneration system forms a closed-loop control through the three-level treatment of membrane separation, chemical precipitation, and adsorption, realizing the efficient recycling of acid and the deep removal of fluoride ions. Compared with the traditional neutralization and discharge process, the acid consumption is reduced, the amount of hazardous waste is reduced, and the operating cost is reduced.

[0029] In the above three processes, the control system is deeply involved in the control, that is, through the real-time detection of the laser confocal sensor and the plasma spectrometer, the corresponding working parameters are dynamically adjusted, which greatly reduces the frequency of manual intervention. Therefore, the use of the pickling treatment equipment for stainless steel pipes solves the technical problems mentioned in the background technology, such as the great harm of HF acid mist, the wastewater containing heavy metals and fluoride ions, the high treatment cost, the long pickling time, the high energy consumption, and the frequent manual intervention.

[0030] In one embodiment, Figure 2 shown.

[0031] The pickling treatment equipment for stainless steel pipe provided in this embodiment has a reaction chamber 1 whose inner wall is made of stainless steel and plated with an alumina ceramic coating, a chamber diameter of the reaction chamber 1 of 500 mm, a chamber length of the reaction chamber 1 of 6 m, one end of the reaction chamber 1 is sealed by a sealing plate 5 with an electrode joint 4, and the other end of the reaction chamber 1 is sealed by an O-ring 6 and a quick-release flange 7. One end of the stainless steel pipe 2 is fixed to the electrode joint 4, an insulating joint 8 is provided on the quick-release flange 7, the insulating joint 8 is coaxial with the electrode joint 4, and the other end of the stainless steel pipe 2 is fixed to the insulating joint 8.

[0032] In this embodiment, the cylindrical reaction chamber 1 is made of 316L stainless steel with an alumina coating on the surface, a length of 6m, a diameter of Φ500mm, and is compatible with a stainless steel tube 2 with a diameter of Φ20-200mm. The cylindrical reaction chamber 1 forms a fully sealed space when working, wherein the electrode connector 4 at one end of the reaction chamber 1 is a grounding electrode. After connecting the stainless steel tube 2, the stainless steel tube 2 itself will serve as a grounding electrode, that is, an anode, corresponding to the multiple groups of annular copper electrodes 3 of the cathode. In addition, the insulating support required for the stainless steel tube 2 is realized by the insulating connector 8 on the quick-release flange 7. Through the setting of the insulating connector 8 and the electrode connector 4, both the requirements of electrical connection and the requirements of mechanical installation are met.

[0033] In one embodiment, the pickling treatment equipment for stainless steel pipes has an RF power supply providing an alternating electric field at a frequency of 13.56 MHz, and the power of the RF power supply is adjusted within a range of 1 to 5 kW according to different diameters of the stainless steel pipe 2 .

[0034] In this embodiment, the frequency used by the radio frequency power source can avoid interference with the communication frequency band. The function of the radio frequency power source is to provide a high-frequency alternating electric field to generate plasma after ionizing the gas.

[0035] In one embodiment, the surface of the annular copper electrode 3 of the pickling treatment equipment for stainless steel pipes is plated with nickel.

[0036] In this embodiment, the annular copper electrode 3 is used as a cathode electrode, and the surface of the annular copper electrode 3 is plated with nickel to prevent corrosion.

[0037] In one embodiment, the composite tank of the pickling treatment equipment for stainless steel pipes includes an alloy lining and a PP shell.

[0038] In this embodiment, a specific material of the composite tank is provided, which is composed of a Hastelloy C276 liner and a PP shell. In terms of the function of use, it is also a composite of two major functions: ultrasonic function and electrolysis function. Ultrasonic wave and electrolysis can produce a synergistic effect, that is, ultrasonic cavitation destroys the passivation film of the oxide layer and accelerates the penetration of the electrolyte; the bubbles generated by the electrolytic reaction are broken by ultrasonic waves to avoid the shielding effect. This greatly shortens the pickling time, and the surface roughness of the stainless steel pipe 2 obtained after pickling is also excellent.

[0039] In one embodiment, the pickling treatment equipment for stainless steel pipe has a pulse power supply with a pulse frequency of 100 to 500 Hz, a duty cycle of 10% to 30%, and a peak current density of 3 to 5 A / dm 2 .

[0040] In this embodiment, a pulse power supply is used, and the electrolyte is allowed to diffuse and replenish during the pulse interval, thereby reducing concentration polarization and lowering the corrosion rate of the metal substrate.

[0041] In one embodiment, the pickling treatment equipment for stainless steel pipes has a plate-and-frame membrane stack formed by alternating anion exchange membranes and acid-resistant flow channel baffles, the membrane material of the anion exchange membrane is a perfluorosulfonic acid ion exchange membrane with a thickness of 0.15 to 0.2 mm, a temperature resistance of ≤60°C, and a pH tolerance range of 0 to 14.

[0042] In this embodiment, a specific structure of a plate-and-frame membrane stack is provided, and the model of the anion exchange membrane can be selected as DF120.

[0043] In one embodiment, the pickling treatment equipment for stainless steel pipes has a stirring device in the primary sedimentation tank, and a dosing device is used to add calcium bicarbonate slurry to the primary sedimentation tank. The adsorbent in the secondary sedimentation tank is modified nano-hydroxyapatite with a specific surface area of ​​≥200m 2 / g, fluorine adsorption capacity ≥20mg / g.

[0044] In this embodiment, the primary sedimentation tank is used as a chemical sedimentation tank, and the secondary sedimentation tank is used as a nano-adsorption tank, which together form a two-stage fluoride ion treatment tank to ultimately achieve deep removal of fluoride ions.

[0045] The above specific implementation methods further describe the invention purpose, technical solutions, and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the protection scope of the present invention. It is particularly pointed out that for those skilled in the art, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A pickling treatment equipment for stainless steel pipe, characterized in that: It includes plasma pretreatment system, fluorine-free electrolytic pickling system, and waste liquid closed-loop regeneration system; The plasma pretreatment system comprises a plasma generator driven by a radio frequency power supply, and further comprises a cylindrical reaction chamber, wherein the reaction chamber is used to accommodate a stainless steel tube, and a plurality of groups of annular copper electrodes are arranged in the reaction chamber, and the plurality of groups of annular copper electrodes are equidistantly distributed along the axial direction of the reaction chamber, and the stainless steel tube passes through the plurality of groups of annular copper electrodes as a grounding electrode, and the plasma generator bombards the surface of the stainless steel tube with low-temperature plasma to loosen the oxide layer; The fluorine-free electrolytic pickling system comprises a composite tank, the electrolyte in the composite tank is a neutral salt solution, a titanium alloy mesh cathode is arranged in the composite tank, the titanium alloy mesh cathode surrounds the outer wall of the stainless steel tube as the anode, and the inter-electrode distance is 5-10 mm, the composite tank is equipped with a pulse power supply connecting the two electrodes, the pulse power supply supplies power for the electrochemical reaction in the composite tank, and an ultrasonic transducer is arranged in the composite tank, the ultrasonic transducer destroys the oxide layer passivation film on the surface of the stainless steel tube through ultrasonic cavitation to accelerate the penetration of the electrolyte; The waste liquid closed-loop regeneration system comprises a diffusion dialysis membrane assembly, the diffusion dialysis membrane assembly comprises a waste liquid flow channel and a recovery liquid flow channel forming a branch, a plate-frame membrane stack is provided at a common front end of the waste liquid flow channel and the recovery liquid flow channel, the recovery liquid flow channel is connected to the composite tank, the waste liquid closed-loop regeneration system also comprises a primary sedimentation tank and a secondary sedimentation tank arranged after the primary sedimentation tank, the waste liquid flow channel is connected to the primary sedimentation tank, a dosing device for adding calcium salt is provided in the primary sedimentation tank, and an adsorbent is provided in the secondary sedimentation tank; The system also includes a control system, which includes a plurality of laser confocal sensors arranged in the plasma pretreatment system and the fluorine-free electrolytic pickling system, and dynamically adjusts the current of the radio frequency power supply, the current of the pulse power supply, and the power of the ultrasonic transducer according to the feedback of the laser confocal sensors. The control system also includes an online plasma spectrometer arranged at the common front end of the waste liquid flow channel and the recovered liquid flow channel, and automatically adjusts the dialysate flow of the diffusion dialysis membrane assembly according to the feedback of the online plasma spectrometer.

2. The pickling treatment equipment for stainless steel pipe according to claim 1, characterized in that: The inner wall of the reaction chamber is made of stainless steel and is coated with an alumina ceramic coating. The chamber diameter of the reaction chamber is 500 mm, the chamber length of the reaction chamber is 6 m, one end of the reaction chamber is sealed by a sealing plate with an electrode connector, and the other end of the reaction chamber is sealed by an O-ring and a quick-release flange.

3. The pickling treatment equipment for stainless steel pipe according to claim 2, characterized in that: One end of the stainless steel tube is fixed on the electrode joint, an insulating joint is provided on the quick-release flange, the insulating joint is coaxial with the electrode joint, and the other end of the stainless steel tube is fixed on the insulating joint.

4. The pickling treatment equipment for stainless steel pipe according to claim 1, characterized in that: The frequency of the alternating electric field provided by the radio frequency power supply is 13.56 MHz, and the power of the radio frequency power supply is adjusted within the range of 1 to 5 kW according to the different diameters of the stainless steel pipe.

5. The pickling treatment equipment for stainless steel pipe according to claim 1, characterized in that: The surface of the annular copper electrode is plated with nickel.

6. The pickling treatment equipment for stainless steel pipe according to claim 1, characterized in that: The composite tank comprises an alloy lining and a PP outer shell.

7. The pickling treatment equipment for stainless steel pipe according to claim 1, characterized in that: The pulse power supply has a pulse frequency of 100-500 Hz, a duty cycle of 10%-30%, and a peak current density of 3-5 A / dm 2 .

8. The pickling treatment equipment for stainless steel pipe according to claim 1, characterized in that: The plate-and-frame membrane stack is formed by alternately stacking anion exchange membranes and acid-resistant flow channel partitions. The membrane material of the anion exchange membrane is a perfluorosulfonic acid ion exchange membrane with a thickness of 0.15 to 0.2 mm, a temperature resistance of ≤60° C., and a pH tolerance range of 0 to 14.

9. The pickling treatment equipment for stainless steel pipe according to claim 1, characterized in that: A stirring device is arranged in the primary sedimentation tank, and the dosing device is used for adding calcium bicarbonate slurry to the primary sedimentation tank.

10. The pickling treatment equipment for stainless steel pipe according to claim 1, characterized in that: The adsorbent is modified nano-hydroxyapatite with a specific surface area of ​​200 m 2 / g, fluorine adsorption capacity ≥20mg / g.

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