CN115855789A - Metal material corrosion monitoring probe and monitoring method - Google Patents
Metal material corrosion monitoring probe and monitoring method Download PDFInfo
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- CN115855789A CN115855789A CN202111122310.7A CN202111122310A CN115855789A CN 115855789 A CN115855789 A CN 115855789A CN 202111122310 A CN202111122310 A CN 202111122310A CN 115855789 A CN115855789 A CN 115855789A
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Abstract
The invention discloses a metal material corrosion monitoring probe and a monitoring method, which can be applied to a refining environment with a metal inner wall surface, and the probe comprises: the metal rod is used as a probe anode, one end of the metal rod is exposed in the refining environment, and the other end of the metal rod is sealed and is connected to the anode of the ammeter and/or the potentiometer through a lead; the metal sheet is used as the negative electrode of the probe, one end of the metal sheet is exposed in the refining environment, and the other end of the metal sheet is sealed and is connected to the negative electrode of the ammeter and/or the potentiometer through a lead; the cross section of the metal sheet is semicircular and is in an insulation state with the metal bar through an insulation sheet; the metal sheet is flush with the exposed end of the metal rod, and the distance between the metal sheet and the exposed end of the metal rod is 0.5-5 mm. The invention can be applied to the field of metal material corrosion monitoring in a refining environment, can adapt to complex gas-liquid-solid multiphase flow environment and can be used for NH 4 The Cl scale corrosion and high flow rate scouring state have applicability.
Description
Technical Field
The invention relates to the technical field of electrochemical monitoring, in particular to a metal material corrosion monitoring probe and a monitoring method applied to a refining environment.
Background
In the industrial production of refining, the corrosion failure of the equipment accounts for more than four times of the total failure times of the equipment, so the corrosion behavior of the equipment in the industrial production of refining needs to be monitored. The traditional equipment corrosion behavior monitoring is calculated through process material physical properties and a corrosion model, and the measurement and calculation accuracy is low due to the problems of limited measurement material types and measurement precision.
Existing refinery environment equipment material corrosion measurement techniques tend to monitor equipment corrosion failure by directly measuring the corrosion behavior of the metal material. Monitoring is carried out in such a way, and the core lies in the design of the corrosion measuring probe in the environment. For example, chinese patent application CN104515732A discloses an apparatus for testing hydrogen permeability of a metal material under high pressure liquid, which comprises an autoclave, an electrochemical workstation, a hydrogen charging device, a metal sheet specimen, a reference electrode, an auxiliary electrode and a thermocouple thermometer. A high-elasticity film is embedded into the upper cover of the hydrogen charging device through a cock with a hole, and the elasticity of the high-elasticity film is utilized to eliminate the internal and external pressure difference, so that the liquid pressure in the hydrogen charging chamber and the liquid pressure in the hydrogen diffusion chamber are kept balanced during testing, and the two different liquids are prevented from being mixed with each other. The device solves the pressure balance problem of different liquids in the hydrogen charging chamber and the hydrogen diffusion chamber under high pressure, can measure hydrogen permeation signals of metal materials in the electrochemical hydrogen charging process under the high pressure of the liquid, and can test and record the anode current density i of various metal materials in the electrochemical hydrogen charging process under different liquid pressures, different temperatures and different hydrogen charging current densities a A time profile, whereby the material is evaluated for susceptibility to hydrogen induced cracking by further data processing analysis. However, this device cannot be used in a pipeline or a reactor in the refining industry.
For another example, chinese patent application CN104537216A discloses an electrochemical prediction method for environmental stress corrosion crack propagation of high-strength steel for pipelines, which can quickly and effectively predict the time for crack propagation and failure of materials in soil due to stress corrosion, so as to solve the unpredictable problem of major accidents caused by stress corrosion cracking of buried pipeline steel in major projects. And obtaining polarization curves of a non-crack tip region and a crack tip region by using a slow-rate scanning polarization curve and a fast-rate scanning polarization curve, selecting a current of the intersection of a zero current potential of the slow-scan polarization curve and the fast-scan polarization curve as the corrosion speed of the crack tip, and providing the relation between the crack propagation time and the electrochemical corrosion rate according to a crack propagation model to predict the service time of the crack. However, this method can only solve the problem of stress corrosion crack propagation for high strength steel, and is also not suitable for monitoring of refining environment.
In the prior art, a probe for directly monitoring equipment material corrosion exists, but the applicability to the refining industrial environment is poor, so that a probe design aiming at the refining industrial environment is urgently needed, the probe can adapt to the complex multiphase flow environment and is used for NH 4 The Cl scale under-corrosion and high-flow-rate scouring state have applicability; the corrosion potential and the corrosion current of the material can be directly monitored on the basis of not monitoring environmental data.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Disclosure of Invention
The invention aims to provide a metal material corrosion monitoring probe and a monitoring method which can be applied to a refining environment, can adapt to a complex gas-liquid-solid multiphase flow environment and can monitor NH 4 The Cl scale corrosion and high flow rate scouring state have applicability.
To achieve the above object, according to a first aspect of the present invention, there is provided a metallic material corrosion monitoring probe for use in a refining environment having a metallic inner wall surface, comprising: the metal rod is used as a probe anode, one end of the metal rod is exposed in the refining environment, and the other end of the metal rod is sealed and is connected to the anode of the ammeter and/or the potentiometer through a lead; the metal sheet is used as the negative electrode of the probe, one end of the metal sheet is exposed in the refining environment, and the other end of the metal sheet is sealed and is connected to the negative electrode of the ammeter and/or the potentiometer through a lead; the cross section of the metal sheet is semicircular and is in an insulation state with the metal bar through an insulation sheet; the metal sheet is flush with the exposed end of the metal rod, and the distance between the metal sheet and the exposed end of the metal rod is 0.5-5 mm.
Further, in the above technical solution, the circumference range of the semicircle may be between 180 degrees and 270 degrees.
Further, in the above technical solution, the probe may have a coating unit, and the coating unit may include: the first insulating groove is of a semi-cylinder structure; and the second insulating groove is of a semi-cylinder structure and forms a surrounding state with the first insulating groove, and the metal sheet, the insulating sheet and the metal bar are tightly wrapped inside from outside to inside in sequence.
Further, in the above technical scheme, the metal sheet, the insulation sheet and the metal bar are tightly attached in sequence, and the size of the gap can be less than or equal to 0.0001mm.
Further, among the above-mentioned technical scheme, the length of metal rod is greater than the length of insulating piece, the length of insulating piece is greater than the length of sheetmetal.
Further, in the above technical scheme, the first insulation groove and the second insulation groove can be fixed by a clamp or a bolt.
Further, in the above technical scheme, the metal sheet may be made of Au, ag, pt, cu, ti, stainless steel, nickel-based alloy or high-entropy alloy.
Further, in the above technical scheme, the metal rod may be made of Au, ag, pt, cu, ti, stainless steel, nickel-based alloy, high-entropy alloy material, or material the same as the metal material to be measured.
Furthermore, in the above technical scheme, the insulation sheet can be made of polytetrafluoroethylene.
Further, in the above technical scheme, the coating unit of the probe may also be a cylindrical structure, and the hollow portion of the cylindrical structure is filled with silica gel.
According to a second aspect of the present invention, there is provided a method of monitoring corrosion of a metallic material for use in a refinery environment having a metallic inner wall surface, comprising the steps of: exposing one end of the metal rod, which is parallel to the metal sheet, in a refining environment, and measuring sample data of corrosion current through an ammeter connected with a lead; obtaining sample data of corrosion rate by performing fixed-point thickness measurement on the inner wall surface of the metal; fitting sample data of an absolute value of corrosion current and corrosion rate to obtain a constant numerical value of a current-rate function; and calculating the corrosion rate of the inner wall surface of the metal to be detected according to the monitored absolute value of the corrosion current and the current-rate function.
Further, in the above technical solution, the current-rate function is y = ax b (ii) a Wherein y is the corrosion rate, x is the absolute value of the corrosion current, and a and b are the constants.
Further, in the above technical solution, the monitoring method may further include: measuring corrosion potential data by a potentiometer connected by a lead; and carrying out qualitative judgment on the corrosion rate through the corrosion potential data.
Further, in the above technical solution, the qualitative judgment may specifically be: when the metal sheet is made of Cu or stainless steel and the metal bar is made of carbon steel, if the measured corrosion potential value is more than-100 mV, the state is judged to be a slight corrosion state; if the measured corrosion potential value is between-100 mV and-500 mV, the corrosion state is judged to be a medium corrosion state; if the measured corrosion potential value is less than-500 mV, the corrosion state is determined to be serious.
Further, in the above technical solution, the qualitative judgment may further specifically be: when the metal sheet is made of Au, ag, pt, ti, nickel-based alloy or high-entropy alloy and the metal bar is made of carbon steel, if the measured corrosion potential value is more than-300 mV, the metal bar is judged to be in a slight corrosion state; if the measured corrosion potential value is between-300 mV and-700 mV, the corrosion state is judged to be a medium corrosion state; if the measured corrosion potential value is less than-700 mV, the corrosion state is determined to be serious.
Compared with the prior art, the invention has the following beneficial effects:
1) The probe of the invention designs the metal sheet into an approximate semicircle, on one hand, the installation is convenient, and in addition, according to the characteristics of the refining environment, a part of NH is deposited on the surface of the metal sheet 4 After the Cl is crystallized, there is still a portionThe position can be conducted in a gas, liquid and solid multiphase flow environment, and the structure has higher measurement reliability;
2) The probe double-electrode has a certain length, a certain margin is reserved for high-flow-rate scouring, and a stable double-electrode long-period guaranteed measurement can be formed even if the probe double-electrode is scoured in a high-flow-rate environment;
3) The distance between the metal sheet and the metal bar is controlled to be close, and the distance between the metal sheet and the metal bar is 0.5-5 mm (namely the thickness of an insulating sheet), so that the required corrosion potential and corrosion current can be more effectively measured in a gas-liquid-solid multiphase flow environment (including a scale environment);
4) By adopting the probe, the corrosion behavior of metal materials such as equipment, pipelines and the like can be monitored on the basis of not monitoring environmental materials, the probe has good durability, and the service cycle is more than ten years;
5) The monitoring method of the invention can not only quantitatively analyze the corrosion rate of the metal material of the equipment or the pipeline in the refining environment through the corrosion current monitored by the probe, but also perform qualitative analysis through the corrosion potential monitored by the probe, and the quantitative and qualitative analysis results can be mutually verified, thereby being simple and rapid and ensuring the accuracy.
The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood and to make the technical means implementable in accordance with the content of the description, and to make the above and other objects, technical features, and advantages of the present invention more comprehensible, one or more preferred embodiments are listed below, and are described in detail below with reference to the accompanying drawings.
Drawings
FIG. 1 is a side view of a metallic material corrosion monitoring probe according to example 1 of the present invention (showing a metallic rod, an insulating sheet, and an exposed end of the metallic sheet).
Fig. 2 is a schematic perspective view of a metal material corrosion monitoring probe according to embodiment 1 of the present invention.
Fig. 3 is a schematic flow chart of a method for monitoring corrosion of a metal material according to embodiment 3 of the present invention.
Fig. 4 is a schematic flow chart of a method for monitoring corrosion of a metal material according to embodiment 4 of the present invention.
Description of the main reference numerals:
1-probe, 10-clip, 11-first insulation slot, 12-second insulation slot, 121-first conductor, 122-second conductor, 13-metal sheet, 14-insulation sheet, 15-metal bar.
Detailed Description
The following detailed description of the present invention is provided in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments.
Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.
Spatially relative terms, such as "below," "lower," "upper," "above," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the article in use or operation in addition to the orientation depicted in the figures. For example, if the items in the figures are turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the elements or features. Thus, the exemplary term "below" can encompass both an orientation of below and above. The articles may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative terms used herein should be interpreted accordingly.
As used herein, the terms "first," "second," and the like are used to distinguish two different elements or regions, and are not intended to define a particular position or relative relationship. In other words, the terms "first," "second," etc. may also be interchanged with one another in some embodiments.
As shown in FIG. 1, the metallic material corrosion monitoring probe 1 of the present invention is applied to a refinery environment having a metallic inner wall surface, includingThe metal bar 15 and the metal sheet 13 of the two poles may further include a wrapping unit wrapping the metal bar 15 and the metal sheet 13. The metal rod 15 is a rod, and serves as a positive electrode of the probe 1, one end of the metal rod is exposed to the refining environment, and the other end of the metal rod is sealed and connected to a positive electrode of an ammeter and/or a potentiometer (not shown in the figure) through a first lead 121. The metal sheet 13 is used as the negative electrode of the probe 1, one end of the metal sheet is exposed in the refining environment, and the other end of the metal sheet is sealed and connected to the negative electrode of the current meter and/or the potentiometer through a second lead. The metal sheet 13 has a semicircular cross section and is insulated from the metal rod 15 by the insulating sheet 14, and the metal sheet 13 is semicircular (preferably, the circumference is 180-270 degrees), so that the installation is convenient, and a part of NH is deposited on the surface of the metal sheet according to the characteristics of the refining environment 4 After Cl is crystallized, parts still can be conducted in a gas, liquid and solid multiphase flow environment, the structure has high measurement reliability, and the problem that the conventional probe is flushed in oil refining equipment can be solved. The metal sheet 13, the insulating sheet 14 and the metal bar 15 are all provided with one end exposed and the exposed end flush, the other end is in a sealing state, and the three extend along the length direction of the probe 1 and sequentially form a wrapping state from outside to inside. Because the probe double electrodes have certain length, certain allowance is reserved for high-flow-rate scouring, and even if scouring is carried out in a high-flow-rate environment, stable double electrodes can be formed to ensure a long period of measurement. The metal sheet 13, the insulating sheet 14 and the metal bar 15 are integrally wrapped by a wrapping unit, and the metal sheet 13, the insulating sheet 14 and the metal bar 15 are sequentially and closely attached, preferably but not limited to, the gap size is 0.0001mm or less. The first and second wires 121 and 122 may be led out from the covering unit, and a sealing process may be performed at the led-out opening. The probe controls the distance between the metal sheet 13 and the metal bar 15 to be relatively close, and the distance between the metal sheet 13 and the metal bar 15 is 0.5-5 mm (namely the thickness of the insulating sheet 14), so that the required corrosion potential and corrosion current can be more effectively measured in a gas-liquid-solid multiphase flow environment (including a scale environment).
Further, preferably, but not limitatively, the length of the metal bar 15 is greater than that of the insulating sheet 14, and the length of the insulating sheet 14 is greater than that of the metal sheet 13. The length design ensures that the other end (namely the sealing end) can keep a step-shaped layer under the condition that the exposed end is flush, and the double-electrode measurement can be still kept under the extreme state of heavier scouring degree of the refining environment, so that the reliability and long periodicity of the measurement are further ensured.
Further, the metal sheet 13 in the probe of the present invention may be made of Au, ag, pt, cu, ti, stainless steel, nickel-based alloy or high-entropy alloy. The metal rod 15 may be made of Au, ag, pt, cu, ti, stainless steel, nickel-based alloy, high-entropy alloy, or the same material as the metal material to be measured. The insulation sheet 14 may be made of teflon.
Example 1
As shown in fig. 1, the probe covering unit of the present embodiment 1 includes: a first insulation groove 11 and a second insulation groove 12. Wherein, the first insulating groove 11 is a semi-cylinder structure; the second insulation groove 12 is also a semi-cylinder structure and is matched with the first insulation groove 11, the first insulation groove 11 and the second insulation groove 12 form a surrounding state, and the metal sheet 13, the insulation sheet 14 and the metal rod 15 are sequentially wrapped inside from outside to inside. The wrapped first insulation groove 11 and the wrapped second insulation groove 12 may be fixed by clips or bolts. This embodiment employs clip attachment, see clip 10 in fig. 2.
In the embodiment, a copper sheet with a length of 40mm, a width of 31.4mm, a thickness of 3mm and a semicircular cross section is selected as the metal sheet 13. A polytetrafluoroethylene cylinder with the length of 45mm, the outer diameter of 10mm, the inner diameter of 9mm and the thickness of 1mm is selected as an insulating sheet 14. A16 MnR (general Low alloy steel) bar-shaped material having a diameter of 9mm and a length of 50mm was selected as the metal bar 15. The semicircle copper sheet is wrapped by the polytetrafluoroethylene cylinder, and the polytetrafluoroethylene cylinder is wrapped by the 16MnR rod-shaped material. One ends of the semicircular copper sheet, the polytetrafluoroethylene cylinder and the 16MnR rod-shaped material are flush, and the other ends of the semicircular copper sheet, the polytetrafluoroethylene cylinder and the 16MnR rod-shaped material respectively weld two strands of the leads (namely the second lead 122 and the first lead 121 which are insulated from each other) to the semicircular copper sheet and the 16MnR rod-shaped material. Selecting a polytetrafluoroethylene first insulation groove 11 and a polytetrafluoroethylene second insulation groove 12 which are 80mm in length and have grooves with one sides of 60mm, enabling a lead to penetrate through holes in the second insulation groove 12, and sealing the holes by using polytetrafluoroethylene and acrylic acid. The first insulation groove 11 and the second insulation groove 12 are wrapped by semicircular copper sheets, polytetrafluoroethylene cylinders and 16MnR rod-shaped materials and compacted. And completely filling the residual slotted gaps after the second insulating groove 12 is wrapped by the semicircular copper sheet, the polytetrafluoroethylene cylinder and the 16MnR rod-shaped material by acrylic resin, pressing the first insulating groove 11 onto the second insulating groove 12, and completely filling the internal slotted gaps by acrylic. The outer portion is fastened by a clip 10, and the first insulation groove 11 and the second insulation groove 12 are tightly combined and left for 24 hours.
The manufactured probe 1 is arranged in a circulating pipeline at the top of a distillation tower, the pipeline is provided with a hole, a lead is led out in a flange sealing mode, the contact part of the lead in the flange is insulated with the metal structure of the flange, and the insulating material adopts polytetrafluoroethylene. The first lead 121 is connected to the positive electrodes of the potentiometer and the ammeter, and the second lead 122 is connected to the negative electrodes of the potentiometer and the ammeter.
Example 2
In this embodiment, a semicircular 316L metal sheet with a length of 50mm, a width of 40mm and a thickness of 2mm is selected as the metal sheet 13. A polytetrafluoroethylene ring with the length of 52mm, the outer diameter of 12mm, the inner diameter of 10mm and the thickness of 2mm is selected as an insulating sheet 14. A rod-shaped material of 20g having a diameter of 10mm and a length of 48mm was selected as the metal rod 15. A316L metal sheet, a polytetrafluoroethylene ring and a 20g rod-shaped material were sequentially compacted from the outside to the inside by a tetrafluoroethylene cylinder having an inner diameter of 14mm and an outer diameter of 16mm, and then a 2205 ring having an inner diameter of 16mm was inserted, and the hollow portion was filled with 304 silica gel. Semicircle 316L, polytetrafluoroethylene ring, 20g rodlike material one end parallel and level, the other end welds two strands in the wire to semicircle 316L sheetmetal and 20g rodlike material respectively. The 2205 material ring is made into a flange, and a lead is connected out of an opening in the flange.
The prepared probe is arranged in a circulating pipeline at the top of the distillation tower, the pipeline is provided with a hole, and two connected leads are respectively connected with the positive pole and the negative pole of a potentiometer and an ammeter.
The metal material corrosion monitoring probes of the embodiment 1 and the embodiment 2 of the invention can solve the problem of poor applicability of the prior art in a complex gas, liquid and solid multiphase flow environment of refining industry, and simultaneously solve the problem of poor durability of the prior art in a refining corrosion environment and a high-flow-rate environment. Through the structural design of the probe, more metal allowance is reserved in the probe, a double-electrode system can be formed after surface scouring, the problem that the corrosion behavior of the metal material is difficult to monitor in the gas, liquid and solid phase high-speed scouring and scale deposition states is solved, and the long-period monitoring of the corrosion behavior of the metal material in the complex environment of the refining industry can be realized. The invention can realize the monitoring of the corrosion behavior of metal materials such as equipment, pipelines and the like on the basis of not monitoring environmental materials, has good durability and has a service cycle of more than ten years.
Example 3
As shown in fig. 3, this embodiment provides a method for monitoring corrosion of a metal material, in which the probe of embodiment 1 or embodiment 2 is used to monitor the corrosion rate, and this embodiment quantitatively analyzes the corrosion rate of the metal material by the measured corrosion current. The method comprises the following steps:
and S101, exposing one end of the metal rod, which is flush with the metal sheet, in a refining environment, and measuring sample data of corrosion current through an ammeter connected with a lead.
For example, the first lead and the second lead are connected to the positive electrode of the potentiometer and the positive electrode of the ammeter, and the negative electrode of the potentiometer and the negative electrode of the ammeter, respectively. The time-current curve was measured with a current meter as shown in the following table (non-sampled data, as measured):
TABLE 1
| Time/s | 10 | 20 | 30 | 40 |
| Absolute value of current/nA | 465962 | 476522 | 596189 | 769057 |
The absolute value of the current gradually increases, indicating that the corrosion of the equipment gradually increases.
And S102, measuring the thickness of the inner wall surface of the metal of the equipment or the pipeline at a fixed point to obtain sample data of the corrosion rate.
And step S103, fitting the sample data of the corrosion current and the corrosion rate to obtain a constant numerical value of a current-rate function. In particular, the current-rate function is y = ax b (ii) a Where y is the corrosion rate, x is the absolute value of the corrosion current, and a and b are constants. The probe can be placed in a simulation pipeline, corrosion current data are recorded for a long time, and the corrosion rate of the simulation pipeline is obtained through fixed-point thickness measurement; the constants a, b are obtained by fitting. And subsequent monitoring in the actual production process does not need fixed-point thickness measurement, and the corrosion rate of the equipment or the pipeline in the actual production process can be obtained only by measuring the corrosion current, taking the absolute value and then substituting the absolute value into the current-rate function.
For example, according to the measurement and calculation of sample data, the conversion relation between the absolute value of the environmental corrosion current and the corrosion rate is as follows: y =1.26 × 10 -12 ×I 1.5 。
And step S104, calculating the corrosion rate of the inner wall surface of the metal to be measured through the absolute value of the corrosion current monitored in the step S101 and the current-rate function in the step S103. The calculated corrosion rates are shown in table 2.
TABLE 2
| Time/s | 10 | 20 | 30 | 40 |
| Absolute value of current/nA | 465962 | 476522 | 596189 | 769057 |
| Corrosion rate/m | 0.000400771 | 0.000414472 | 0.000580025 | 0.000849784 |
By the monitoring method of the embodiment 3, the corrosion rate of the equipment or the pipeline metal material in the refining environment can be quantitatively analyzed through the corrosion current monitored by the probe, and the method is simple and quick and can ensure the accuracy.
Example 4
As shown in fig. 4, this embodiment provides a method for monitoring corrosion of a metal material, in which the probe of embodiment 1 or embodiment 2 is used to monitor the corrosion rate, and this embodiment quantitatively analyzes the corrosion rate of the metal material through the measured corrosion current, and qualitatively analyzes the corrosion rate of the metal material through the measured corrosion potential. The method comprises the following steps:
step S201, exposing one end of the metal rod and the metal sheet which are parallel and level to a refining environment, and measuring sample data of corrosion current through an ammeter connected with a lead.
For example, the first and second wires are connected to the positive electrodes of a potentiometer and an ammeter, and the negative electrodes of the potentiometer and the ammeter, respectively. The time-current curve was measured with a current meter as shown in the following table (non-sampled data, as measured):
TABLE 3
| Time/s | 10 | 20 | 30 | 40 |
| Absolute value of current/nA | 26512 | 25782 | 24328 | 23739 |
The absolute value of the current gradually decreases, indicating that the corrosion of the equipment gradually decreases.
Step S202, the thickness of the inner wall surface of the metal of the equipment or the pipeline is measured at a fixed point, and sample data of the corrosion rate is obtained.
Step S203, obtaining a constant numerical value of the current-rate function through sample data fitting of the corrosion current and the corrosion rate. In particular, the current-rate function is y = ax b (ii) a Wherein y is the corrosion rateX is the absolute value of the corrosion current, and a and b are constants. The probe can be placed in a simulation pipeline, corrosion current data is recorded for a long time, and the corrosion rate of the simulation pipeline is obtained through fixed-point thickness measurement; the constants a, b are obtained by fitting. And subsequent monitoring in the actual production process does not need fixed-point thickness measurement, and the corrosion rate of the equipment or the pipeline in the actual production process can be obtained only by measuring the corrosion current, taking the absolute value and substituting the absolute value into the current-rate function.
For example, according to the measurement and calculation of sample data, the conversion relation between the absolute value of the environmental corrosion current and the corrosion rate is as follows: y =1.26 × 10 -12 ×I 1.5 . The data in table 3 can be converted by the function to obtain the corresponding corrosion rate.
Step S204, calculating the corrosion rate of the inner wall surface of the metal to be measured according to the corrosion current monitored in step S201 and the current-rate function in step S203.
In step S205, corrosion potential data is measured by a potentiometer connected through a wire. This step may be performed simultaneously with step S201. For example: the time-potential curve was measured with a potentiometer as shown in the following table:
TABLE 4
| Time/s | 10 | 20 | 30 | 40 |
| potential/mV | -495.2 | -462.0 | -432.9 | -415.2 |
In step S206, the corrosion rate is qualitatively determined from the corrosion potential data in step S205. The qualitative judgment can specifically adopt the following modes: when the metal sheet is made of Cu or stainless steel, if the measured corrosion potential value is more than-100 mV, the metal sheet is judged to be in a slight corrosion state; if the measured corrosion potential value is between-100 mV and-500 mV, the corrosion state is judged to be a medium corrosion state; if the measured corrosion potential value is less than-500 mV, the corrosion state is determined to be serious. When the metal sheet is made of Au, ag, pt, ti, nickel-based alloy or high-entropy alloy, if the measured corrosion potential value is more than-300 mV, the metal sheet is judged to be in a slight corrosion state; if the measured corrosion potential value is between-300 mV and-700 mV, judging the corrosion state is a medium corrosion state; if the measured corrosion potential value is less than-700 mV, the state is judged to be a serious corrosion state.
Since the method of this example uses Cu or stainless steel as the metal sheet and carbon steel as the metal rod, the data potential in Table 4 is gradually increased, indicating that the corrosion is gradually reduced, but in a moderate corrosion state.
By the monitoring method of embodiment 4, not only can the corrosion rate of the metal material of the equipment or the pipeline in the refining environment be quantitatively analyzed through the corrosion current monitored by the probe, but also the corrosion potential monitored by the probe can be qualitatively analyzed, the quantitative and qualitative analysis results can be mutually verified, and the method is simple, rapid and capable of ensuring the accuracy.
The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications. Any simple modifications, equivalent changes and modifications made to the above exemplary embodiments shall fall within the scope of the present invention.
Claims (15)
1. A metallic material corrosion monitoring probe for use in a refinery environment having a metallic interior wall surface, comprising:
the metal rod is used as a probe anode, one end of the metal rod is exposed in the refining environment, and the other end of the metal rod is sealed and is connected to the anode of the ammeter and/or the potentiometer through a lead;
the metal sheet is used as a probe cathode, one end of the metal sheet is exposed in the refining environment, and the other end of the metal sheet is sealed and is connected to the cathode of the ammeter and/or the potentiometer through a lead; the cross section of the metal sheet is semicircular and is in an insulation state with the metal bar through an insulation sheet; the metal sheet is flush with the exposed end of the metal rod, and the distance between the metal sheet and the exposed end of the metal rod is 0.5-5 mm.
2. The metallic material corrosion monitoring probe of claim 1, wherein said semi-circle has a circumferential extent between 180 degrees and 270 degrees.
3. The metallic material corrosion monitoring probe of claim 1, wherein said probe has a cladding unit comprising:
the first insulating groove is of a semi-cylinder structure;
the second insulation groove, it be the half cylinder structure and with first insulation groove forms the surrounding state, from outside-in proper order will sheetmetal, insulating piece and metal bar closely wrap up inside.
4. The metallic material corrosion monitoring probe of claim 3, wherein the metallic sheet, the insulating sheet and the metallic rod are closely attached in sequence, and the gap size is 0.0001mm or less.
5. The metallic material corrosion monitoring probe of claim 1, wherein the length of said metallic rod is greater than the length of an insulating sheet, said insulating sheet having a length greater than the length of the metallic sheet.
6. The metallic material corrosion monitoring probe of claim 3, wherein the first and second insulation grooves are fixed by a clip or a bolt.
7. The metallic material corrosion monitoring probe of claim 1, wherein the metallic sheet is made of Au, ag, pt, cu, ti, stainless steel, ni-based alloy or high entropy alloy.
8. The metallic material corrosion monitoring probe of claim 1, wherein the metallic rod is made of Au, ag, pt, cu, ti, stainless steel, ni-based alloy, high entropy alloy material, or the same material as the metallic material to be measured.
9. The metallic material corrosion monitoring probe of claim 1, wherein said insulating sheet is made of teflon.
10. The metallic material corrosion monitoring probe according to claim 1, wherein the probe has a covering unit having a cylindrical structure, and a hollow portion of the cylindrical structure is filled with silica gel.
11. A metal material corrosion monitoring method is characterized by being applied to a refining environment with a metal inner wall surface, and comprising the following steps:
exposing one end of the metal rod, which is parallel to the metal sheet, in the refining environment, and measuring sample data of corrosion current through an ammeter connected with a lead;
obtaining sample data of corrosion rate by performing fixed-point thickness measurement on the inner wall surface of the metal;
fitting the sample data of the corrosion current absolute value and the corrosion rate to obtain a constant numerical value of a current-rate function;
and calculating the corrosion rate of the inner wall surface of the metal to be detected according to the monitored absolute value of the corrosion current and the current-rate function.
12. The metallic material corrosion monitoring method of claim 11, wherein the current-rate function is y = ax b (ii) a Wherein y is the corrosion rate, x is the absolute value of the corrosion current, and a and b are the constants.
13. The metallic material corrosion monitoring method according to claim 11 or 12, further comprising:
measuring corrosion potential data by a potentiometer connected by a lead;
and carrying out qualitative judgment on the corrosion rate according to the corrosion potential data.
14. The method for monitoring corrosion of metallic material according to claim 13, wherein the qualitative determination is specifically: when the metal sheet is made of Cu or stainless steel and the metal rod is made of carbon steel,
if the measured corrosion potential value is more than-100 mV, judging the corrosion state to be a slight corrosion state;
if the measured corrosion potential value is between-100 mV and-500 mV, judging the corrosion state to be a medium corrosion state;
and if the measured corrosion potential value is less than-500 mV, judging the corrosion state to be a serious corrosion state.
15. The method for monitoring corrosion of metallic material according to claim 13, wherein when said metallic sheet is made of Au, ag, pt, ti, ni-based alloy or high-entropy alloy and said metallic rod is made of carbon steel,
if the measured corrosion potential value is more than-300 mV, judging the corrosion state to be a slight corrosion state;
if the measured corrosion potential value is between-300 mV and-700 mV, judging the corrosion state to be a medium corrosion state;
and if the measured corrosion potential value is less than-700 mV, judging the corrosion state to be a serious corrosion state.
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