A three-electrode flow cell and corrosion simulation test method

Abstract

The present invention discloses a three-electrode circulation cell and a corrosion simulation test method, comprising a circulation cell body; the circulation cell body comprises a vertical circulation pipe section and a horizontal circulation pipe section, the horizontal circulation pipe section is arranged on one side of the upper end of the vertical circulation pipe section; a vertical through groove is arranged along the axis in the vertical circulation pipe section, a horizontal through groove is arranged along the axis in the horizontal circulation pipe section, the vertical through groove and the horizontal through groove are connected to form an L-shaped through groove, and a test liquid is passed into the L-shaped through groove; an electrode mounting groove is provided at the top of the vertical circulation pipe section, and an electrode sealing cover is fitted in the electrode mounting groove; a working electrode and an auxiliary electrode are vertically inserted in the electrode sealing cover; an electrode mounting hole is provided on the other side of the upper end of the vertical circulation pipe section, a Luggin capillary is fitted in the electrode mounting hole, and a reference electrode is inserted in the Luggin capillary; the present invention realizes a true simulation of the accelerated flow of a 90° elbow pipe of an air-cooled island, ensures the authenticity of the simulation test, and has high accuracy in the test results.

Description

Technical Field

[0001] The invention belongs to the technical field of flow accelerated corrosion testing, and in particular relates to a three-electrode flow cell and a corrosion simulation test method. Background Art

[0002] At present, in electrochemical corrosion tests, a flat platinum sheet is generally used as the auxiliary electrode and a saturated calomel electrode is used as the reference electrode. The metal material to be tested is made into a test piece of a preset area, and a wire is welded to the back of the test piece and then encapsulated with epoxy resin. The working surface of the test piece is then polished and degreased and used as the working electrode.

[0003] Existing electrochemical three-electrode corrosion testing devices are only suitable for static corrosion simulation test processes under normal temperature and pressure conditions in open systems. Among them, both the working electrode and the auxiliary electrode are hangers and immersed in the test liquid, which cannot meet the requirements of 90° high-flow rate flushing corrosion simulation tests on air-cooled islands. At the same time, the saturated calomel electrode has a relatively limited scope of application when used as a reference electrode, and the traditional test solution is neutral and contains chloride ions. Moreover, in acidic, alkaline, or chloride-free test solutions, a salt bridge is usually required. The anions and cations in the salt bridge will enter the test solution, causing contamination of the test solution. The agar used to seal the electrode usually melts at 85°C, close to the upper limit of the operating temperature of the air-cooled island, making it unusable. Therefore, it cannot meet the requirements of high-temperature, oxygen-free air-cooled island corrosion simulation. Summary of the Invention

[0004] In response to the technical problems existing in the prior art, the present invention provides a three-electrode flow cell and a corrosion simulation test method to solve the technical problem that the existing three-electrode flow cell cannot truly simulate the accelerated flow corrosion conditions of the 90° elbow in the air-cooling island, resulting in large errors in the simulation test results.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The present invention provides a three-electrode flow cell, comprising a flow cell body, a Luggin capillary, an electrode sealing gland, a working electrode, a reference electrode, and an auxiliary electrode; the flow cell body comprises a vertical flow pipe section and a horizontal flow pipe section, the horizontal flow pipe section being horizontally arranged on one side of an upper end of the vertical flow pipe section; a vertical through groove is arranged along the axis of the vertical flow pipe section, and a horizontal through groove is arranged along the axis of the horizontal flow pipe section, the vertical through groove and the horizontal through groove being connected to form an L-shaped through groove, and a test liquid is passed into the L-shaped through groove;

[0007] An electrode mounting groove is provided at the top of the vertical flow pipe section, and the electrode sealing gland is fitted in the electrode mounting groove; wherein the lower end surface of the electrode sealing gland is flush with and in communication with the upper edge surface of the corner of the L-shaped flow groove; the working electrode and the auxiliary electrode are vertically inserted into the electrode sealing gland, and the lower end surfaces of the working electrode and the auxiliary electrode are both flush with the lower end surface of the electrode sealing gland;

[0008] An electrode mounting hole is provided on the other side of the upper end of the vertical circulation pipe section, one end of the electrode mounting hole is communicated with the corner side wall of the L-shaped flow trough, and the other end of the electrode mounting hole is communicated with the side wall surface of the vertical circulation pipe section; the Luggin capillary is inserted into the electrode mounting hole, and the reference electrode is arranged in the Luggin capillary; wherein, the tip of the Luggin capillary extends to below the lower end surface of the working electrode, and the tail end of the Luggin capillary extends to the outside of the vertical circulation pipe section; the first end of the reference electrode extends to the tip of the Luggin capillary, and the second end of the reference electrode is led out from the tail end of the Luggin capillary.

[0009] Furthermore, a circulation pool inlet is provided at the lower end of the vertical circulation pipe section, the circulation pool inlet is connected to the lower end of the vertical through groove, and a circulation pool inlet joint is installed at the circulation pool inlet; the extended end of the horizontal circulation pipe section is provided with a circulation pool outlet, the circulation pool outlet is connected to the horizontal through groove, and a circulation pool outlet joint is installed at the circulation pool outlet.

[0010] Furthermore, a capillary exhaust port is provided on the side wall of the tail end of the Luggin capillary, and a water stop clamp is installed at the capillary exhaust port; the distance between the tip of the Luggin capillary and the lower end surface of the working electrode is greater than or equal to the diameter of the Luggin capillary.

[0011] Furthermore, the working electrode and the auxiliary electrode both adopt inverted T-shaped cylindrical electrodes; the inverted T-shaped cylindrical electrode includes an upper cylindrical section and a lower cylindrical section coaxially connected; wherein, the lower end surface of the lower cylindrical section is the electrode working surface; the electrode working surface is flush with the lower end surface of the electrode sealing cover.

[0012] Furthermore, the material of the inverted T-shaped cylindrical electrode is the same as the equipment material of the air-cooling island; the ratio of the upper end surface area of the upper cylindrical segment to the lower end surface area of the lower cylindrical segment is 1:(10-20); the distance between the electrode working surface of the working electrode and the electrode working surface of the auxiliary electrode is 1-5mm.

[0013] Furthermore, the reference electrode is made of platinum wire; wherein, at the tail end of the Luggin capillary, the reference electrode and the Luggin capillary are sealed with molten glass.

[0014] Furthermore, it also includes a corrosion tester; the upper end of the working electrode, the second end of the reference electrode and the upper end of the auxiliary electrode are all connected to the input end of the corrosion tester.

[0015] Furthermore, the test liquid is an alkalizer or an oxidizer; wherein the alkalizer and the oxidizer are single-phase flow or gas-liquid two-phase flow; the temperature of the test liquid is 0-100°C, the flow rate is 0-50m / s, the hydrogen conductivity is less than 0.3μS / cm, and the dissolved oxygen value is less than 10ppb.

[0016] Furthermore, a capillary sealing plug is provided between the Luggin capillary and the electrode mounting hole. The capillary sealing plug is installed in the electrode mounting hole through threaded sealing. A central through hole is provided in the center of the capillary sealing plug, and the Luggin capillary seal is inserted into the central through hole.

[0017] The electrode sealing gland includes a gland body and an annular fixing plate. The gland body is sealingly mounted in the electrode mounting groove. Two vertical through holes for mounting the working electrode and the auxiliary electrode are provided in the gland body; wherein the shape of the vertical through holes matches the outer shape of the working electrode or the auxiliary electrode; the annular fixing plate is fixedly sleeved on the outer side of the upper end of the gland body, and the annular fixing plate is tightly fixed to the outer side of the top end of the vertical circulation pipe section; wherein the annular fixing plate is connected to the top end of the vertical circulation pipe section by bolts.

[0018] The present invention also provides a corrosion simulation test method, which utilizes the three-electrode flow cell to simulate the flow-accelerated corrosion process of a 90° elbow in an air-cooling island;

[0019] The corrosion simulation test method comprises the following steps:

[0020] Install the working electrode, reference electrode and auxiliary electrode, and introduce the test solution into the L-shaped flow channel;

[0021] Expel the air from the Luggin capillary;

[0022] Record the polarization resistance of the working electrode, the polarization resistance of the reference electrode, and the polarization resistance of the auxiliary electrode respectively;

[0023] According to the polarization resistance of the working electrode, the polarization resistance of the reference electrode and the polarization resistance of the auxiliary electrode, the corrosion results of the working electrode, the reference electrode and the auxiliary electrode are determined, and then the flow accelerated corrosion simulation test results of the 90° elbow in the air cooling island are obtained.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention provides a three-electrode flow cell and a corrosion simulation test method, wherein a horizontal flow pipe section is horizontally arranged on one side of the upper end of a vertical flow pipe section, and the vertical through groove is connected to the horizontal through groove to form an L-shaped through groove; a working electrode and an auxiliary electrode are vertically inserted into an electrode sealing cover, and the lower end surface of the working electrode and the lower end surface of the auxiliary electrode are flush with the lower end surface of the electrode sealing cover, and it is ensured that the working surfaces of the working electrode and the auxiliary electrode are flush with the upper edge surface of the corner of the L-shaped through groove; a reference electrode is arranged in a Luggin capillary, and the tip of the Luggin capillary is extended to below the lower end surface of the working electrode; the working electrode, the auxiliary electrode and the reference electrode are installed at the corner of the L-shaped through groove, and the necking of the L-shaped through groove and the 90° hedging effect at its corner are utilized to achieve a true simulation of the accelerated flow of the 90° elbow of the air-cooled island, thereby achieving a true simulation of the fluid hedging corrosion working condition, ensuring the authenticity of the simulation test, and the device structure is simple and the test results are highly accurate.

[0026] Furthermore, a circulation pool inlet is set at the lower end of the vertical circulation pipe section, and a circulation pool outlet is set at the extended end of the horizontal circulation pipe section, and an inlet joint and an outlet joint are installed at the circulation pool inlet and the circulation pool outlet respectively, so as to facilitate the quick connection of the circulation pool body with the test liquid supply and recovery equipment; at the same time, since the fluid in the L-shaped flow pool is in a high flow rate state, in order to better simulate the effect of 90° counterattack, the bottom inlet and top outlet are adopted to reduce the degree of turbulence of the fluid in the vertical circulation pipe section and the horizontal circulation pipe section, thereby ensuring that the flow state of the fluid is relatively stable, thereby ensuring the metering accuracy of the 90° counterattack electrode group.

[0027] Furthermore, a capillary exhaust port is opened on the side wall of the tail end of the Luggin capillary and a water stop clamp is installed. By opening and closing the water stop clamp, the capillary exhaust port can be opened or closed to meet the requirements of exhausting the air in the Luggin capillary during the simulation test to simulate the anaerobic conditions.

[0028] Furthermore, since the test current flowing through the solution between the working electrode and the reference electrode will generate an ohmic voltage drop, the distance between the tip of the Luggin capillary and the lower end surface of the working electrode is designed to be greater than or equal to the diameter of the Luggin capillary, so that the Luggin capillary is close to the working electrode. On the one hand, this eliminates the influence of the ohmic voltage drop, and on the other hand, reduces the shielding effect of the capillary itself on the electric lines on the surface of the working electrode.

[0029] Furthermore, the working electrode and the auxiliary electrode both adopt inverted T-shaped cylindrical electrodes, which are convenient for the installation of the electrodes and can effectively prevent the fluid from being ejected when the high-speed fluid is counter-charged against the electrodes; the traditional electrode sealing method uses epoxy resin filler for sealing, which requires polishing after sealing, which is time-consuming and labor-intensive, has weak resistance to cold and hot changes, and is prone to cracks after being subjected to cold and hot shocks. Leakage is prone to occur in high-speed counter-charge experiments, resulting in high detection noise and pollution to the dosing test circulation system; secondly, the upper cylindrical section of the inverted T-shaped cylindrical electrode can be directly connected to the corrosion tester through a wire to avoid poor contact.

[0030] Furthermore, the ratio of the upper end surface area of the upper cylindrical segment to the lower end surface area of the lower cylindrical segment is 1:(10-20), which is convenient for processing and manufacturing; at the same time, the upper cylindrical segment can be used as a wire to facilitate connection with the corrosion tester; the auxiliary electrode plays the role of forming a complete circuit, and when the distance between the electrode working surface of the working electrode and the electrode working surface of the auxiliary electrode is 1-5mm, isolation is formed to prevent short circuit.

[0031] Furthermore, the Luggin capillary is fixed by a capillary sealing plug, and the working electrode and the auxiliary electrode are fixed by an electrode sealing gland, which facilitates the replacement and maintenance of the test electrodes and the cleaning of the circulation cell body. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A longitudinal cross-sectional view of the three-electrode flow cell of the present invention;

[0033] Figure 2 It is a structural schematic diagram of the electrode sealing cover in the present invention.

[0034] Among them, 1 flow cell body, 2 L-type flow slot, 3 flow cell inlet, 4 flow cell inlet connector, 5 flow cell outlet connector, 6 flow cell outlet, 7 Luggin capillary, 8 capillary sealing plug, 9 electrode sealing cover, 10 working electrode, 11 reference electrode, 12 water stop clamp, 13 capillary exhaust port, 14 auxiliary electrode, 15 cover bolt hole, 16 first sealing ring, 17 second sealing ring, 18 corrosion tester. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail in the following specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] As attached Figure 1-2The present invention provides a three-electrode flow cell, including a flow cell body 1, a flow cell inlet joint 4, a flow cell outlet joint 5, a Luggin capillary 7, a capillary sealing plug 8, an electrode sealing cover 9, a working electrode 10, a reference electrode 11, a water stop clamp 12, an auxiliary electrode 14, a first sealing ring 16, a second sealing ring 17 and a corrosion tester 18.

[0037] The circulation pool body 1 includes a vertical circulation pipe section and a horizontal circulation pipe section, and the vertical circulation pipe section and the horizontal circulation pipe section are both rectangular organic glass structures; the vertical circulation pipe section is vertically arranged, and the horizontal circulation pipe section is horizontally arranged on one side of the upper end of the vertical circulation pipe section; wherein, the first end of the horizontal circulation pipe section is vertically fixedly connected to one side of the upper end of the vertical circulation pipe section, and the second end of the horizontal circulation pipe section extends horizontally toward a side away from the vertical circulation pipe section; preferably, the horizontal circulation pipe section and the vertical circulation pipe section are integrally formed.

[0038] A vertical through groove is provided along the axis in the vertical circulation pipe section, and a horizontal through groove is provided along the axis in the horizontal circulation pipe section. The vertical through groove is connected to the horizontal through groove to form an L-shaped through groove 2, and a test liquid is passed into the L-shaped through groove 2; preferably, the test liquid is an alkalizer or an oxidizer, and the alkalizer and the oxidizer are single-phase flow or gas-liquid two-phase flow; the temperature of the test liquid is 0-100°C, the flow rate of the test liquid is 0-50m / s, the hydrogen conductivity of the test liquid is less than 0.3μS / cm, and the dissolved oxygen value of the test liquid is less than 10ppb.

[0039] In which, the fluid flow cross-section of the L-shaped circulation groove 2 is a rectangular cross-section; the lower end of the vertical circulation pipe section is provided with a circulation pool inlet 3, the circulation pool inlet 3 is connected to the lower end of the vertical through groove, and the circulation pool inlet joint 4 is installed at the circulation pool inlet 3; the circulation pool inlet joint 4 is used to be connected to the device for storing the test liquid; preferably, the circulation pool inlet joint 4 and the circulation pool inlet 3 are threadedly connected; the extended end of the horizontal circulation pipe section is provided with a circulation pool outlet 6, the circulation pool outlet 6 is connected to the horizontal through groove, and the circulation pool outlet joint 5 is installed at the circulation pool outlet 6; the circulation pool outlet joint 6 is connected to the device for recovering the test liquid; preferably, the circulation pool outlet joint 5 and the circulation pool inlet 3 are threadedly connected.

[0040] An electrode mounting groove is provided at the top of the vertical circulation pipe section, and the electrode sealing cover 9 is mounted in the electrode mounting groove; wherein, the lower end surface of the electrode sealing cover 9 is flush with the upper edge surface of the corner of the L-shaped flow groove 2 and is connected; it should be noted that the corner of the L-shaped flow groove 2 is the intersection of the vertical through groove and the horizontal through groove; the working electrode 10 and the auxiliary electrode 14 are vertically inserted into the electrode sealing cover 9, and the lower end surface of the working electrode 10 and the lower end surface of the auxiliary electrode 14 are both flush with the lower end surface of the electrode sealing cover 9; that is, the lower end surface of the working electrode 10 and the lower end surface of the auxiliary electrode 14 are also flush with the upper edge surface of the corner of the L-shaped flow groove 2; the upper end of the working electrode 10 and the upper end of the auxiliary electrode 14 respectively extend to the outer side of the upper end of the electrode sealing cover 9.

[0041] Specifically, the electrode sealing gland 9 includes a gland body and an annular fixing plate, the shape of the gland body matches the structure of the electrode mounting groove; the gland body is fitted in the electrode mounting groove, and the first sealing ring 16 and the second sealing ring 17 are sequentially sleeved on the outside of the gland body from top to bottom; wherein, one side of the first sealing ring 16 or the second sealing ring 17 is sealed in contact with the outer circumferential surface of the gland body, and the other side of the first sealing ring 16 or the second sealing ring 17 is in close contact with the inner wall of the electrode mounting groove; preferably, the electrode mounting The groove is a cylindrical groove, and the gland body is a circular cylindrical structure; two vertical through holes for installing the working electrode 10 and the auxiliary electrode 14 are provided in the gland body, and the two vertical through holes are arranged in parallel and spaced apart; wherein, the shape of the vertical through hole matches the shape of the working electrode 10 or the auxiliary electrode 14, the working electrode 10 is vertically inserted into one of the vertical through holes, and the auxiliary electrode 14 is vertically inserted into the other vertical through hole; preferably, the distance between the electrode working surface of the working electrode 10 and the electrode working surface of the auxiliary electrode 14 is 1-5 mm.

[0042] The working electrode 10 and the auxiliary electrode 14 both adopt inverted T-shaped cylindrical electrodes, and the inverted T-shaped cylindrical electrode includes an upper cylindrical section and a lower cylindrical section that are coaxially connected; wherein, the lower end surface of the lower cylindrical section is the electrode working surface, and the upper end of the upper cylindrical section extends to the outer side of the upper end of the vertical through hole and serves as the electrode lead-out end, which is used to be connected to the corrosion tester 18 through a wire; the electrode working surface is flush with the lower end surface of the electrode sealing cover 9, that is, the electrode working surface is flush with the upper edge surface of the corner of the L-shaped flow groove 2; the material of the inverted T-shaped cylindrical electrode is the same as the equipment material of the air-cooling island, and the diameter of the upper cylindrical section is smaller than the diameter of the lower cylindrical section; preferably, the inverted T-shaped cylindrical electrode is made of carbon steel, and the ratio of the upper end surface area of the upper cylindrical section to the lower end surface area of the lower cylindrical section is 1:(10-20).

[0043] It should be noted that the vertical through hole includes an upper cylindrical hole and a lower cylindrical hole, the aperture and length of the upper cylindrical hole are matched with the outer diameter and length of the upper cylindrical section, and the space and length of the lower cylindrical hole are matched with the outer diameter and length of the lower cylindrical section; the upper end of the upper cylindrical hole is provided with a first annular groove, a first O-ring is installed in the first annular groove, one side of the first O-ring is in close contact with the first annular groove, and the other side of the first O-ring is in close contact with the outer side of the upper end of the upper cylindrical section; the upper end of the lower cylindrical hole is provided with a second annular groove, a second O-ring is installed in the second annular groove, and one side of the second O-ring is in close contact with the second annular groove Tight contact, the other side of the second O-ring is in close contact with the outer side of the upper end of the lower cylindrical section; by arranging the first O-ring and the second sealing ring between the inverted T-shaped cylindrical electrode and the vertical through hole, the high-speed fluid counter-electrode is effectively prevented from being sprayed out; because the traditional epoxy resin filler needs to be polished after sealing, it is time-consuming and labor-intensive, and has weak resistance to cold and heat changes. It is easy to crack after being subjected to cold and heat shocks, and leakage is easy to occur in high-speed counter-electrode experiments, resulting in high detection noise and pollution to the dosing test circulation system; compared with the traditional epoxy resin filler electrode sealing method, it has high sealing performance, good resistance to cold and heat changes, is not prone to leakage, and has less pollution to the dosing test circulation system.

[0044] The annular fixing plate is fixedly sleeved on the outer side of the upper end of the gland body and tightly fixed to the outer side of the top end of the vertical circulation pipe section, and the annular fixing plate and the top end of the vertical circulation pipe section are connected by bolts; wherein, a number of gland bolt holes 15 are evenly opened on the annular fixing plate, and a number of end face bolt holes are evenly opened on the top end of the vertical circulation pipe section, and the gland bolt holes 15 and the end face bolt holes are arranged in a one-to-one correspondence; the bolts are T-bolts, and the T-bolts are successively passed through and fixed in the gland bolt holes 15 and the end face bolt holes to fix the annular fixing plate and the vertical circulation pipe section together, thereby realizing the fixed connection between the electrode sealing gland 9 and the vertical flow pipe section; preferably, the annular fixing plate and the gland body adopt an integrally formed structure.

[0045] An electrode mounting hole is provided on the other side of the upper end of the vertical circulation pipe section, one end of the electrode mounting hole is communicated with the corner side wall of the L-shaped flow channel 2, and the other end of the electrode mounting hole is communicated with the side wall surface of the vertical circulation pipe section; the Luggin capillary 7 is inserted into the electrode mounting hole, the tip of the Luggin capillary 7 extends below the lower end surface of the working electrode 10, and the tail end of the Luggin capillary 7 extends to the outside of the vertical circulation pipe section; preferably, the distance between the tip of the Luggin capillary 7 and the lower end surface of the working electrode 10 is greater than or equal to the diameter of the Luggin capillary 7; because the test current flowing through the solution between the working electrode and the reference electrode will generate an ohmic voltage drop, when the distance between the tip of the Luggin capillary 7 and the lower end surface of the working electrode 10 is set to be greater than or equal to the diameter of the Luggin capillary 7, the Luggin capillary 7 is close to the working electrode, which, on the one hand, eliminates the influence of the ohmic voltage drop, and on the other hand, reduces the shielding effect of the capillary itself on the electric lines of force on the surface of the working electrode.

[0046] A capillary sealing plug 8 is further provided between the Luggin capillary 7 and the electrode mounting hole. The capillary sealing plug 8 is installed in the electrode mounting hole by threaded sealing. A central through hole is provided in the center of the capillary sealing plug 8, and the Luggin capillary 7 is sealed and inserted into the central through hole. Preferably, the inner diameter of the central through hole matches the outer diameter of the Luggin capillary 7, and a sealing ring is provided between the outer wall of the Luggin capillary 7 and the inner wall of the central through hole for sealing. A capillary exhaust port 13 is provided on the side wall of the tail end of the Luggin capillary 7, and a water stop clamp 12 is installed at the capillary exhaust port 13. The capillary exhaust port 13 is used to exhaust the air in the Luggin capillary 7; the reference electrode 11 is arranged in the Luggin capillary 7; wherein the first end of the reference electrode 11 extends to the tip of the Luggin capillary 7, and the second end of the reference electrode 11 is led out from the tail end of the Luggin capillary 7; wherein the second end of the reference electrode 11 is connected to the corrosion tester 18 through a wire; the reference electrode 11 is made of platinum wire, and one end of the reference electrode 11 extends to the; wherein, at the tail end of the Luggin capillary 7, the reference electrode 11 and the Luggin capillary 7 are sealed with molten glass.

[0047] The upper end of the working electrode 10, the second end of the reference electrode 11 and the upper end of the auxiliary electrode 14 are respectively connected to the input end of the corrosion tester 18 through wires; wherein, the corrosion tester 18 is used to collect the polarization resistance of the test electrode, and the test electrode includes the working electrode 10, the reference electrode 11 and the auxiliary electrode 14.

[0048] The present invention also provides a corrosion simulation test method, which utilizes the above-mentioned three-electrode flow cell to simulate the flow of a 90° elbow in an air-cooled island to accelerate the corrosion process; wherein the corrosion simulation test method is specifically as follows:

[0049] Step 1: After installing the working electrode 10, auxiliary electrode 14 and reference electrode 11, add an alkalizer or oxidant into the L-shaped flow channel 2 through the circulation pool inlet 3; wherein the alkalizer or oxidant is a single-phase flow or a gas-liquid two-phase flow that meets the test requirements.

[0050] Step 2: Open the water-stop clamp 12 on the Luggin capillary tube 7 to exhaust the air in the Luggin capillary tube 7.

[0051] Step 3: Turn on the corrosion tester 18 and record the polarization resistance of the working electrode 10, the polarization resistance of the reference electrode 11 and the polarization resistance of the auxiliary electrode 14 respectively;

[0052] Step 4: Determine the corrosion results of the working electrode 10, the reference electrode 11, and the auxiliary electrode 14 based on the polarization resistance of the working electrode 10, the polarization resistance of the reference electrode 11, and the polarization resistance of the auxiliary electrode 14, and then obtain the flow-accelerated corrosion simulation test results of the 90° elbow in the air-cooled island.

[0053] Working principle:

[0054] The three-electrode flow cell described in the present invention arranges an L-shaped flow groove 2 in the flow cell body 1 which is spliced by a vertical flow pipe section and a horizontal flow pipe section, and utilizes the vertical flow groove and the horizontal flow groove of the L-shaped flow groove 2 to minimize the turbulence of the fluid in the vertical flow pipe section and the horizontal flow pipe section, thereby ensuring the stability of the fluid flow state at the corner of the L-shaped flow groove 2, thereby realizing a true simulation of the 90° elbow in the air-cooled island, and further ensuring the metering accuracy of the 90° counter-electrode group; the polarization resistance of the test electrode is monitored and collected by a corrosion tester 18, and the corrosion condition of the test electrode is characterized according to the polarization resistance, thereby realizing a true simulation of the air-cooled island equipment.

[0055] In the present invention, the flow cell body 1 adopts an inverted L-shaped structure formed by splicing a vertical flow pipe section and a horizontal flow pipe section. The flow cell body 1 is made of organic glass, which is convenient for visual observation of the accelerated flow corrosion process; the two ends of the flow cell body 1 are respectively provided with a flow cell inlet 3 and a flow cell outlet 6; the flow cell body 1 is provided with an L-shaped flow groove 2 along the axis, and the two ends of the L-shaped flow groove 2 are respectively connected to the flow cell inlet 3 and the flow cell outlet 6; an electrode mounting groove is provided at the upper end of the corner of the L-shaped flow groove 2, and an electrode mounting hole is provided on the corner side wall of the L-shaped flow groove 2 and away from the side of the horizontal flow pipe section; the electrode seal is used The gland 9 fixes the working electrode 10 and the auxiliary electrode 14 in the electrode mounting groove. The electrode sealing gland 9 is fixedly connected to the top of the vertical circulation pipe section by a T-bolt. The electrode sealing gland 9 is sealed and connected to the inner wall of the electrode mounting groove by a first sealing ring 16 and a second sealing ring 17 spaced apart in an upper and lower manner. The lower end surface of the working electrode 10 and the lower end surface of the auxiliary electrode 14 serve as their respective electrode working surfaces, and the electrode working surfaces are flush with the upper edge surface of the L-shaped circulation groove 2. The Luggin capillary 7 is sealed and fixed to the electrode mounting hole by a capillary sealing plug 8, and the reference electrode 11 is arranged at the center of the Luggin capillary 7.

[0056] In the present invention, the tip of the Luggin capillary 7 is located below the electrode working surface of the working electrode 10 and is as close to the electrode working surface of the working electrode 10 as possible, and the tip of the Luggin capillary 7 does not contact the electrode working surface of the working electrode 10; since the Luggin capillary 7 itself has a shielding effect on the wire on the surface of the working electrode 10, when the tip of the Luggin capillary 7 is as close as possible to the working surface of the working electrode 10, the shielding effect of the Luggin capillary 7 can be effectively reduced; preferably, the distance between the tip of the Luggin capillary 7 and the lower end surface of the working electrode 10 is greater than or equal to the diameter of the Luggin capillary 7; a capillary exhaust port 13 is provided on the side wall of the tail end of the Luggin capillary 7, and a water stop clamp 12 is installed at the capillary exhaust port 13. By opening and closing the water stop clamp 12, the capillary exhaust port 13 is opened or closed to meet the requirements of exhausting the air in the Luggin capillary 7 during the simulation test to simulate the anaerobic conditions.

[0057] In the present invention, the working electrode 10 and the auxiliary electrode 14 both adopt inverted T-shaped cylindrical electrodes, and the lower end surface of the inverted T-shaped cylindrical electrode serves as the electrode working surface; and the electrode working surface of the working electrode 10 is the same size as the electrode working surface of the auxiliary electrode 14, and both are circular; the lower end surface of the inverted T-shaped cylindrical electrode is flush with and connected to the upper edge surface of the corner of the L-shaped flow groove 2 or the lower end surface of the electrode sealing cover 9; the diameter of the lower end surface of the inverted T-shaped cylindrical electrode is the same as the lateral width of the main view of the L-shaped flow groove 2, and the length of the left view direction of the L-shaped flow groove 2 can accommodate the electrode working surface of the working electrode and the electrode working surface of the auxiliary electrode; wherein, the distance between the electrode working surface of the working electrode 10 and the electrode working surface of the auxiliary electrode 14 is 1-5mm; preferably, the distance between the electrode working surface of the working electrode 10 and the electrode working surface of the auxiliary electrode 14 is 1.5mm.

[0058] In the present invention, the capillary sealing plug 8 is made of polytetrafluoroethylene, polypropylene or nylon, and the capillary sealing plug 8 is connected to the vertical circulation pipe section by a threaded connection; the electrode sealing cover 9 is made of polytetrafluoroethylene, and is connected to the top of the vertical circulation pipe section by a T-shaped bolt through the electrode sealing cover 9; the circulation pool inlet joint and the circulation pool outlet joint are stainless steel joints, and are threadedly sealed with the circulation pool body 1; the reference electrode 11 is a platinum wire, one end of the platinum wire is introduced into the tip of the Luggin capillary 7, and the other end of the platinum wire is connected to the input end of the corrosion tester 18 through a wire; wherein, the platinum wire and the tail end of the Luggin capillary 7 are sealed by molten glass; the working electrode 10 and the auxiliary electrode 14 are both made of carbon steel, the same as the equipment material of the air-cooled island.

[0059] Due to the high-velocity water vapor flowing to the air-cooled condenser, it is disturbed by the pipe bends, baffles or pipe diameter changes, resulting in relatively strong turbulence, local formation of high-speed fluid, and intensification of the "scouring and impact" effect of droplets on the metal surface; in the present invention, the working electrode, auxiliary electrode and reference electrode are installed at the corners of the L-shaped flow channel, and the L-shaped flow channel is connected to a thick pipe and reduced in diameter to form a flow channel slit; secondly, the hedging at the corners of the L-shaped flow channel conforms to the actual situation of pipe turning, baffles and pipe diameter changes in field conditions; the electrode circulation pool described in the present invention can simulate the 90° elbow of the air-cooled island to achieve the most realistic simulation of the fluid hedging corrosion working condition, thereby ensuring the authenticity of the simulation test; secondly, the test electrode adopts a three-electrode combination of a working electrode, a reference electrode and an auxiliary electrode, which effectively eliminates the influence of the resistance of the pure water solution on the electrochemical corrosion measurement; the components connected to the three-electrode flow cell are all detachable, and in the event of a failure, they are convenient to dismantle and replace, convenient maintenance, meet the simulation of high flow rate and anaerobic conditions, and the simulation test results have small errors.

[0060] The above embodiment is only one of the implementation methods that can realize the technical solution of the present invention. The scope of protection claimed by the present invention is not limited only to this embodiment, but also includes changes, replacements and other implementation methods that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention.

Claims

1. A three-electrode flow cell, characterized in that The invention comprises a flow cell body (1), a Luggin capillary (7), an electrode sealing cover (9), a working electrode (10), a reference electrode (11) and an auxiliary electrode (14); the flow cell body (1) comprises a vertical flow pipe section and a horizontal flow pipe section, the horizontal flow pipe section is horizontally arranged on one side of the upper end of the vertical flow pipe section; a vertical through groove is arranged along the axis of the vertical flow pipe section, a horizontal through groove is arranged along the axis of the horizontal flow pipe section, the vertical through groove is connected to the horizontal through groove to form an L-shaped through groove (2), and a test liquid is passed into the L-shaped through groove (2); An electrode mounting groove is provided at the top end of the vertical flow pipe section, and the electrode sealing cover (9) is mounted in the electrode mounting groove; wherein the lower end surface of the electrode sealing cover (9) is flush with the upper edge surface of the corner of the L-shaped flow groove (2) and is connected thereto; the working electrode (10) and the auxiliary electrode (14) are vertically inserted into the electrode sealing cover (9), and the lower end surface of the working electrode (10) and the lower end surface of the auxiliary electrode (14) are both flush with the lower end surface of the electrode sealing cover (9); An electrode mounting hole is provided on the other side of the upper end of the vertical circulation pipe section, one end of the electrode mounting hole is communicated with the corner side wall of the L-shaped flow groove (2), and the other end of the electrode mounting hole is communicated with the side wall surface of the vertical circulation pipe section; the Luggin capillary (7) is inserted into the electrode mounting hole, and the reference electrode (11) is inserted into the Luggin capillary (7); wherein the tip of the Luggin capillary (7) extends to below the lower end surface of the working electrode (10), and the tail end of the Luggin capillary (7) extends to the outside of the vertical circulation pipe section; the first end of the reference electrode (11) extends to the tip of the Luggin capillary (7), and the second end of the reference electrode (11) is led out from the tail end of the Luggin capillary (7); A flow pool inlet (3) is provided at the lower end of the vertical flow pipe section, the flow pool inlet (3) is communicated with the lower end of the vertical through slot, and a flow pool inlet joint (4) is installed at the flow pool inlet (3); a flow pool outlet (6) is provided at the extended end of the horizontal flow pipe section, the flow pool outlet (6) is communicated with the horizontal through slot, and a flow pool outlet joint (5) is installed at the flow pool outlet (6); A capillary exhaust port (13) is provided on the side wall of the tail end of the Luggin capillary (7), and a water stop clamp (12) is installed at the capillary exhaust port (13); the distance between the tip of the Luggin capillary (7) and the lower end surface of the working electrode (10) is greater than or equal to the diameter of the Luggin capillary (7); The working electrode (10) and the auxiliary electrode (14) are both inverted T-shaped cylindrical electrodes; the inverted T-shaped cylindrical electrode comprises an upper cylindrical section and a lower cylindrical section coaxially connected; wherein the lower end surface of the lower cylindrical section is the electrode working surface; the electrode working surface is flush with the lower end surface of the electrode sealing cover (9); The material of the inverted T-shaped cylindrical electrode is the same as the equipment material of the air-cooling island; the ratio of the upper end surface area of the upper cylindrical section to the lower end surface area of the lower cylindrical section is 1:(10-20); and the distance between the electrode working surface of the working electrode (10) and the electrode working surface of the auxiliary electrode (14) is 1-5 mm.

2. A three-electrode flow cell according to claim 1, characterized in that: The reference electrode (11) is made of platinum wire; wherein, at the tail end of the Luggin capillary (7), the reference electrode (11) and the Luggin capillary (7) are sealed with molten glass.

3. A three-electrode flow cell according to claim 1, characterized in that: It also includes a corrosion tester (18); the upper end of the working electrode (10), the second end of the reference electrode (11) and the upper end of the auxiliary electrode (14) are all connected to the input end of the corrosion tester (18).

4. A three-electrode flow cell according to claim 1, characterized in that: The test liquid is an alkalizer or an oxidizer; wherein the alkalizer and the oxidizer are single-phase flow or gas-liquid two-phase flow; the temperature of the test liquid is 0~100°C, the flow rate is 0~50m / s, the hydrogen conductivity is less than 0.3μS / cm, and the dissolved oxygen value is less than 10ppb.

5. A three-electrode flow cell according to claim 1, characterized in that: A capillary sealing plug (8) is further provided between the Luggin capillary (7) and the electrode mounting hole. The capillary sealing plug (8) is installed in the electrode mounting hole through threaded sealing. A central through hole is provided at the center of the capillary sealing plug (8), and the Luggin capillary (7) is sealed and inserted into the central through hole. The electrode sealing gland (9) comprises a gland body and an annular fixing plate, wherein the gland body is sealingly mounted in the electrode mounting groove, and two vertical through holes for mounting the working electrode (10) and the auxiliary electrode (14) are provided in the gland body; wherein the shape of the vertical through holes matches the outer shape of the working electrode (10) or the auxiliary electrode (14); the annular fixing plate is fixedly sleeved on the outer side of the upper end of the gland body, and the annular fixing plate is tightly fixed to the outer side of the top end of the vertical circulation pipe section; wherein the annular fixing plate is connected to the top end of the vertical circulation pipe section by bolts.

6. A corrosion simulation test method, characterized in that: Using the three-electrode flow cell according to any one of claims 1 to 5 to simulate the flow-accelerated corrosion process of a 90° elbow in an air-cooled island; The corrosion simulation test method comprises the following steps: Install the working electrode (10), the reference electrode (11) and the auxiliary electrode (14), and introduce the test liquid into the L-shaped flow channel (2); Expel the air from the Luggin capillary (7); Recording the polarization resistance of the working electrode (10), the polarization resistance of the reference electrode (11), and the polarization resistance of the auxiliary electrode (14) respectively; According to the polarization resistance of the working electrode (10), the polarization resistance of the reference electrode (11) and the polarization resistance of the auxiliary electrode (14), the corrosion results of the working electrode (10), the reference electrode (11) and the auxiliary electrode (14) are determined, and then the flow accelerated corrosion simulation test results of the 90° elbow in the air cooling island are obtained.

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