JP2004028818A - Method for monitoring corrosive environment and its apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow for signal variations when measuring electric signals which indicate changes in corrosive environments and to correctly and accurately estimate and display the stat of corrosion of structures, apparatuses, and piping from corroding speeds which change moment by moment. <P>SOLUTION: For estimating corrosive damage in a nuclear reactor, steam piping, a condenser, and water piping in contact with reactor water and cooling water, an corrosive environment detecting apparatus is connected to a measurement processing device via a lead wire from electrochemical sensor A. A computer 14 is provided with the function of computing corrosion resistance R (R=σ<SB>E</SB>/σ<SB>i</SB>) from a potential standard deviation σ<SB>E</SB>and a current standard deviation σ<SB>i</SB>measured by the electrochemical sensor A; the function of storing a calibration curve which indicates the relation between the corrosion resistance R and the corroding speeds previously measured by an electrochemical sensor F; and a monitor 15 for comparing the corrosion resistance R measured by the electrochemical sensor A with the calibration curve, computing, and displaying the corroding speeds. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technology for measuring a corrosive environment by using electrochemical means for structures, equipment, and piping used in power plants and chemical plants such as nuclear power plants. The present invention relates to a method and an apparatus for monitoring a corrosive environment for holding.
[0002]
[Prior art]
Among structures, devices, and piping (hereinafter, referred to as “structures, etc.”) of power plants or chemical plants such as nuclear power plants and thermal power plants, as structures that come into contact with water and steam using high-purity water, In particular there are reactors, steam piping, turbines, condensers and water piping. The materials of these structures and the like are generally made of corrosion-resistant stainless steel, and the corrosion progresses slowly, but the corrosion of the structures and the like progresses slowly after an incubation period.
[0003]
However, since the corrosion of the structure and the like surely progresses, for example, for the structure of a nuclear power plant, etc., from the viewpoints of efficient operation and importance on safety, it is extremely high that can withstand a corrosive environment for a long time. Corrosion resistance is required, and the development of advanced corrosion measurement technology and advanced corrosion suppression technology is required to suppress the progress of the corrosive environment, and to prevent problems such as nuclear power plant structures due to the corrosive environment. Is a necessary condition.
[0004]
Factors that affect the progress of corrosion in nuclear power plant structures include water quality, temperature, and flow velocity of the water that comes into contact with the structures, and other factors such as the materials of the structures, residual stress, and any unevenness. The differences cause different corrosion mechanisms.
[0005]
That is, regarding the corrosion of structures and the like of a nuclear power plant, they can be roughly classified into stress corrosion cracking in which corrosion cracks progress due to residual stress in the structures and the like, and pitting corrosion in which corrosion progresses due to some unevenness.
[0006]
Stress corrosion cracking is a phenomenon in which a structure or the like has residual stress or an external stress acts on it, causing a tensile stress in the structure or the like, and the interaction between the tensile stress and the corrosive environment accelerates the corrosion of the structure and the like. , A corrosion mechanism in which cracks occur.
[0007]
In addition, pitting corrosion refers to a corrosion mechanism that occurs in a localized manner on a metal surface of a structure or the like particularly in an environment of a halogen and an anion containing a halogen, and erodes more strongly in a depth direction than an opening. As one example, there is crevice corrosion in which corrosion progresses in a depth direction from a crevice opening due to structural nonuniformity due to a crevice structure or a defect structure of a structure or the like.
[0008]
For example, as disclosed in Japanese Patent Application Laid-Open No. 2001-166082, there is a method of detecting a corrosive environment such as a structure that comes into contact with reactor water or cooling water, and a method of operating a nuclear power plant using the same. In a method for detecting a corrosive environment such as a structure that comes into contact with reactor water or cooling water, an electrical signal detected from a test piece, a reference electrode, and a reference test piece immersed in a liquid to be measured is converted into a corrosion potential and a corrosion potential. This is to detect corrosion as an electric current, and to estimate corrosion damage to a structure or the like by detecting an excessive change in a corrosive environment from an obtained excessive corrosion potential or an excessive corrosion current.
[0009]
In the method of detecting corrosive environments such as structures that come into contact with reactor water or cooling water, test specimens must have a residual stress structure in order to operate nuclear power plants soundly, and excessive changes in corrosive environments should be detected. By estimating the occurrence of stress corrosion cracking of structures with residual stress, or by using a test piece as a gap structure and detecting an excessive change in the corrosion environment, crevice corrosion of a structure with a gap structure, etc. By estimating damage caused by (pitting corrosion) and taking appropriate measures, a technique for preventing the deterioration of the corrosive environment is disclosed, thereby contributing to the development of advanced corrosion measurement techniques and advanced corrosion suppression techniques.
[0010]
[Problems to be solved by the invention]
Since corrosion in a structure or the like in a plant such as a nuclear power plant is not substantially the entire corrosion of the metal surface of the structure or the like, according to Japanese Patent Application Laid-Open No. 2001-166082, an output signal of the obtained corrosion potential and corrosion current is obtained. Have variations due to noise and spots of corrosion.
[0011]
Furthermore, since the test piece for measuring the corrosion potential and the corrosion current, the reference electrode and the reference test piece are each made of the same material, the actually measured corrosion potential and corrosion current are very small.
[0012]
Therefore, the output signal of the corrosion potential and the corrosion current is largely controlled by noise and the variation of the corrosion, so that the S / N ratio is small. There is a high possibility that the behavior of the current will be misrepresented, and the measurement accuracy of the corrosion information of a structure or the like is not sufficient.
[0013]
In Japanese Patent Application Laid-Open No. 2001-166082, corrosion damage of a structure of a nuclear power plant can be estimated based on an excessive change in corrosion potential and an excessive change in corrosion current. Can not judge.
[0014]
Incidentally, there is a corrosion rate that can determine the corrosion state of a structure or the like, and the corrosion rate can be measured by actually measuring a change in the weight of the test piece. However, if the measurement of the change in the weight of the test piece is used, there is a disadvantage that the corrosion phenomenon is disturbed by the operation of removing the test piece necessary for the actual measurement of the change in the weight of the test piece. Performing the test specimen removal operation directly reduces the measurement accuracy. Further, it is difficult to directly take out the test piece at the time of corrosion measurement.
[0015]
Lastly, in Japanese Patent Application Laid-Open No. 2001-166082, a test piece is made to have a residual stress structure or a gap structure, and by detecting an excessive change in a corrosive environment, the occurrence of stress corrosion cracking of structures and the like and damage due to gap corrosion are reduced. As guessed, it is difficult to manufacture a test piece having a form equivalent to the form of the actual structure or the like, and there is a difference in the corrosion state between the actual structure or the like and the test piece.
[0016]
The present invention has been proposed in order to solve such a problem, and measures an electrical signal indicating a change in a corrosive environment, and considers a variation in the signal, so that a structure, an apparatus, and a piping can be measured. It is an object of the present invention to provide a corrosive environment monitoring method and apparatus capable of accurately and accurately estimating and displaying corrosion damage of a steel plate.
[0017]
Another object of the present invention is to provide a corrosion environment monitoring method and apparatus capable of accurately and accurately estimating and displaying the corrosion state of structures, equipment, and piping from a corrosion rate that changes every moment, and displaying the estimated corrosion state. .
[0018]
Further, a third object of the present invention is to provide a corrosion environment monitoring method and apparatus capable of accurately estimating and displaying the corrosion state of structures, equipment and piping by directly obtaining corrosion information from a material to be measured and displaying the corrosion state. To provide.
[0019]
[Means for Solving the Problems]
The corrosion environment monitoring method according to the present invention, as described in claim 1, in order to solve the above-described problem, uses water flowing in the plant as a liquid to be measured, and further includes a plant structural material in contact with the liquid to be measured. Corrosion in which a change in corrosion potential E and a corrosion current i detected from the liquid to be measured is detected as a change in the corrosive environment of the liquid to be measured in order to estimate corrosion damage of the material to be measured. In the environment detection method, a potential standard deviation σ of the corrosion potential E according to a predetermined time width._EAnd a current standard deviation σ of the corrosion current i according to a predetermined time width._iCalculating the potential standard deviation and the current standard deviation on a monitor to estimate a change in the corrosive environment of the liquid to be measured from the potential standard deviation and the current standard deviation. And characterized in that:
[0020]
Further, according to the corrosion environment monitoring method of the present invention, the corrosion resistance R (R = σ) is calculated from the potential standard deviation and the corrosion current standard deviation._E/ Σ_i) Is calculated, and the corrosion resistance R is prepared in advance using various test pieces and various liquids to be measured, and stored in a computer with reference to a calibration curve representing a relationship between the corrosion resistance R and the corrosion rate. It is characterized in that a change in the corrosion environment of the liquid to be measured is estimated from the obtained corrosion rate.
[0021]
Further, as described in claim 3, the corrosion environment monitoring device of the present invention uses water flowing in the plant as a liquid to be measured, and further uses a plant structural material that is in contact with the liquid to be measured as a material to be measured. In order to estimate the corrosion damage of the measurement material, the test piece and the reference electrode are provided for measuring the corrosion potential E of the liquid to be measured, while the test piece and the reference test piece are respectively provided for measuring the corrosion current i. In a corrosive environment detecting device connected from a sensor to a measurement processing device via a lead wire, a computer is used as the measurement processing device, and the computer is provided with a potential standard deviation σ according to a predetermined time width of the corrosion potential._EAnd the computer calculates the current standard deviation σ of the corrosion current by a predetermined time width._iAnd a monitor for displaying changes in the potential standard deviation and the current standard deviation in the computer.
[0022]
According to the corrosion environment monitoring device of the present invention, as described in claim 4, a corrosion resistance R (R = σ) is calculated by the computer based on the potential standard deviation and the current standard deviation._E/ Σ_i), A function of storing a calibration curve group representing the relationship between the corrosion resistance R and the corrosion rate as a database, and extracting a calibration curve corresponding to the material to be measured and the liquid to be measured from the calibration curve group. And a function of estimating the corrosion rate by comparing the calculated corrosion resistance R with the calibration curve.
[0023]
Further, as set forth in claim 5, the corrosion environment monitoring device of the present invention includes the electrochemical sensor provided with a reference electrode for measuring a corrosion potential, and a reference test piece for measuring a corrosion current. The present invention is characterized in that a chemical sensor is connected to a computer via a lead wire, and a material to be measured is connected to a computer via a lead wire.
[0024]
Further, the corrosion environment monitoring device of the present invention is characterized in that the test piece has a structure in which a stress is applied by applying a static strain, as described in claim 6.
[0025]
Further, the corrosion environment monitoring device of the present invention is characterized in that the test piece has a gap structure as described in claim 7.
[0026]
In the corrosion environment monitoring apparatus according to the present invention, the computer is a first computer, and a terminal of the first computer is connected to a terminal of a second computer at a remote place by a network system. It is characterized by having done.
[0027]
Finally, the corrosion environment monitoring device of the present invention is characterized in that the computer is provided with interactive software for inputting a material to be measured, a liquid to be measured, and other measurement conditions, as described in claim 9. I do.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a method and apparatus for monitoring a corrosive environment according to the present invention will be described with reference to the accompanying drawings.
[0029]
FIG. 1 is a schematic diagram showing a first embodiment of a corrosion environment monitoring device according to the present invention.
[0030]
In the corrosive environment monitoring device 1, a liquid to be measured 12 is supplied into a material to be measured 11 as a structure, equipment, or piping of a plant. The material to be measured 11 is, for example, SUS304, and the liquid to be measured 12 is, for example, a NaCl solution.
[0031]
An electrochemical sensor A is immersed in the liquid to be measured 12, and the electrochemical sensor A is electrically connected to a computer 14 via a lead wire. The computer 14 has a monitor 15.
[0032]
Further, the electrochemical sensor A is provided with a test piece b, a reference electrode c and a reference test piece d, all of which are made of the same material as the material 11 to be measured. However, the test piece b may be made of platinum.
[0033]
When the shapes of the test piece b, the reference electrode c, and the reference test piece d are plate-like, the surface part and the side part, or the edge part and the central part of the test piece b, the reference electrode c, and the reference test piece d, respectively. Therefore, the shape is desirably a thin disk, and pretreatment such as polishing and washing is performed as necessary.
[0034]
Further, although one electrochemical sensor A is shown in the corrosive environment monitoring device 1 of FIG. 1, a plurality of electrochemical sensors A are immersed in the liquid to be measured 12 for measurement, and output information of this measurement is obtained. By performing processing using a statistical method, a measurement result with higher reproducibility can be obtained.
[0035]
First, the corrosion potential E is measured between the test piece b and the reference electrode c provided in the electrochemical sensor A of the corrosion environment monitoring device 1, and at the same time, between the test piece b and the reference test piece d provided in the electrochemical sensor A. The corrosion current i is measured.
[0036]
FIG. 2 is a schematic graph showing an example of corrosion potential fluctuation and corrosion current fluctuation.
[0037]
The graph of FIG. 2 shows the corrosion potential in the case where the material of the material to be measured 11 is SUS304, the liquid quality of the solution to be measured 12 is 3 wt% NaCl solution, the liquid temperature is 80 ° C., the flow rate is no, and the measurement interval is 0.5 second. It is a measurement result of the time course of E and corrosion current i. The upper part of FIG. 2 shows a time-series corrosion potential fluctuation 21 and the lower part shows a time-series corrosion current fluctuation 22. For the sake of explanation, a graph in which a part of each of the corrosion potential fluctuation 21 and the corrosion current fluctuation 22 is enlarged is shown as an enlarged potential fluctuation 23 and an expanded current fluctuation 24.
[0038]
Here, in the enlarged potential fluctuation 23, the number of measurements of the corrosion potential E over a predetermined time width Δt is n, and the measured value of the corrosion potential E is E_n, The average of the measured values_barThen
(Equation 1)
σ_E= Σ (E_n-E_bar)²/ N
, The potential standard deviation σ_EIs calculated.
[0039]
Similarly, in the enlarged current fluctuation 24, the number of measurements of the corrosion current i in a predetermined time width Δt is n, and the measurement value of the corrosion current i is i_n, The average of the measured values is i_barThen
(Equation 2)
σ_i= Σ (i_n−i_bar)²/ N
Current standard deviation σ_iIs calculated.
[0040]
Finally, the calculated potential standard deviation σ_EAnd current standard deviation σ_iIs displayed on the monitor 15, it is possible to evaluate the variation due to the change in the corrosive environment on the basis of the variation due to the noise of the signal and the variation due to the unevenness of the corrosion. I can guess.
[0041]
Further, a stress test piece b1 shown in FIG. 3A or a stress test piece b2 shown in FIG. 3B is used as the test piece b of the electrochemical sensor A provided in the corrosion environment monitoring device 1 of FIG.
[0042]
The stress test piece b1 of FIG. 3A is provided with a flat plate or a disk 30 bent in a U-shape in the electrochemical sensor A, and the flat plate or the disk 30 is fixed by a bolt 31 and a nut 32, and A static strain is applied to apply a stress to the disk 30. The stress test piece b2 shown in FIG. 3B has a fixing jig 33 provided on the electrochemical sensor A, and a flat plate or a disk 30 is fixed to the fixing jig 33. A static strain is applied to apply a stress to the disk 30.
[0043]
As the test piece b provided in the corrosive environment monitoring apparatus 1, a stress test piece b1 shown in FIG. 3A or a stress test piece b2 shown in FIG._EAnd current standard deviation σ_iIs calculated and displayed. That is, the occurrence of stress corrosion cracking in the material to be measured 11 having residual stress is accurately and accurately estimated by evaluating the variation due to the change in the corrosive environment with reference to the variation due to signal noise and the variation due to corrosion spots. it can.
[0044]
Further, a gap test piece b3 shown in FIG. 4A is used as a test piece b of the electrochemical sensor A provided in the corrosion environment monitoring device 1 of FIG.
[0045]
In the gap test piece b3 of FIG. 4A, a flat plate or a disk 35 is provided on the electrochemical sensor A, and the flat plate or the disk 35 is brought into contact with an auxiliary flat plate or an auxiliary disk 36, and is connected with a bolt 37 and a nut 38. By doing so, a gap is given to the flat plate or the disk 35. FIG. 4B shows a side view of FIG. 4A.
[0046]
As a test piece b provided in the corrosive environment monitor 1, a gap test piece b3 shown in FIG._EAnd current standard deviation σ_iIs calculated and displayed. That is, by evaluating the variation due to the change in the corrosive environment on the basis of the variation due to the noise of the signal and the variation due to the unevenness of the corrosion, it is possible to accurately and accurately estimate the occurrence of the crevice corrosion in the material to be measured 11 having the gap structure. .
[0047]
As described above, according to the corrosive environment monitoring device 1 of FIG. 1, an electrical signal indicating a change in corrosive environment is measured, and by considering the variation of this signal, corrosion damage of structures, equipment, and piping is reduced. Guess and display accurately and accurately.
[0048]
FIG. 5 is a schematic diagram showing a second embodiment of the corrosion environment monitoring device according to the present invention.
[0049]
In the corrosive environment monitoring device 1A, the measured liquid 12 is supplied into a predetermined container 41. An electrochemical sensor F is immersed in the liquid to be measured 12 in the container 41, and the electrochemical sensor F is electrically connected to the computer 14 via a lead wire.
[0050]
The liquid to be measured 12 in the container 41 is brought close to the flow velocity of the liquid to be measured 12 in the material to be measured 11 by artificially generating a water flow using a pump as necessary.
[0051]
Further, the electrochemical sensor F is provided with a test piece b, a reference electrode c, and a reference test piece d, all of which are made of the same material as the material 11 to be measured. However, the test piece b may be made of platinum.
[0052]
In FIG. 5, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.
[0053]
First, the corrosion potential E is measured between the test piece b and the reference electrode c provided in the electrochemical sensor F of the corrosion environment monitoring device 1A, and at the same time, between the test piece b and the reference test piece d provided in the electrochemical sensor F. The corrosion current i is measured.
[0054]
Further, the computer 14 calculates the potential standard deviation σ from the corrosion potential E and the corrosion current i according to the above-described equations (1) and (2)._EAnd current standard deviation σ_iIs calculated,
(Equation 3)
R = σ_E/ Σ_i
Is calculated from the relationship. At the same time, a calibration curve representing the relationship between the corrosion resistance R and the corrosion rate is created by actually measuring the change in the test piece weight as the corrosion rate.
[0055]
Further, a calibration curve group representing the relationship between the corrosion resistance R and the corrosion rate was produced by repeating the operation of producing various calibration curves corresponding to various combinations of the material 11 and the liquid 12 to be measured. , As a database.
[0056]
Subsequently, by setting and inputting the material and form of the material to be measured 11, the liquid quality, the liquid temperature, and the flow velocity of the liquid to be measured 12 to the computer 14 of the corrosive environment monitoring device 1 </ b> A, measurement is performed from the prepared calibration curve group. Extract the calibration curve corresponding to the condition.
[0057]
Next, similarly to the operation of the corrosive environment monitoring device 1 of FIG._EAnd current standard deviation σ_iIs calculated.
[0058]
Next, the computer 14 shown in FIG._EAnd current standard deviation σ_iFrom the corrosion resistance R.
[0059]
Finally, the calculated corrosion resistance R is referred to the extracted calibration curve, and the corrosion rate obtained by referring to the reference is displayed on the monitor 15 so that the corrosion environment of the test liquid 12 in the test object 11 can be measured. Without directly measuring the corrosion rate, it is possible to accurately and accurately estimate the constantly changing corrosion state of the workpiece 11.
[0060]
In FIG. 5, although the electrochemical sensor A and the electrochemical sensor F are connected to the computer 14 at the same time, the electrochemical sensor F is connected to the computer 14, and the computer 14 creates a database. After disconnecting the sensor F, the computer 14 may be connected to the electrochemical sensor A.
[0061]
Further, as a test piece b of the electrochemical sensor A and the electrochemical sensor F provided in the corrosion environment monitoring device 1A of FIG. 5, a stress test piece b1 shown in FIG. 3A or a stress test piece shown in FIG. The corrosion rate of the liquid 12 to be measured is displayed using b2. That is, by evaluating the change in the corrosion rate in the corrosive environment, the state of the stress corrosion cracking of the material to be measured 11 having the residual stress can be accurately and accurately estimated.
[0062]
In addition, a corrosion test piece b3 shown in FIG. 4A is used as a test piece b of the electrochemical sensor A and the electrochemical sensor F provided in the corrosion environment monitoring device 1A of FIG. Is displayed. That is, by evaluating the change in the corrosion rate in the corrosive environment, the state of crevice corrosion of the workpiece 11 having the crevice structure can be accurately and accurately estimated.
[0063]
As described above, according to the corrosion environment monitoring apparatus 1A of FIG. 5, it is possible to accurately and accurately estimate and display the corrosion state of structures, equipment, and piping from the corrosion rate that changes every moment.
[0064]
FIG. 6 is a schematic diagram showing a third embodiment of the corrosion environment monitoring device according to the present invention.
[0065]
The corrosion environment monitoring device 1B of FIG. 6 is different from the corrosion environment monitoring device 1A of FIG. 5 in that a computer that stores a calibration curve group prepared in advance as a database is remote from a computer in which corrosion potential and corrosion current are measured. This is a system that monitors the corrosion status of structures, equipment, and piping with a computer at a location away from the measurement site.
[0066]
In the corrosion environment monitoring device 1B, the liquid to be measured 12 is supplied into the material to be measured 11. An electrochemical sensor A is immersed in a liquid to be measured 12 in a material to be measured 11, and the electrochemical sensor A is electrically connected to a computer 14 via a lead wire.
[0067]
Further, the electrochemical sensor A is provided with a test piece b, a reference electrode c and a reference test piece d, all of which are made of the same material as the material 11 to be measured. However, the test piece b may be made of platinum.
[0068]
On the other hand, in the corrosive environment monitoring device 1B, the measured liquid 12 is supplied into the container 41. The electrochemical sensor F is immersed in the liquid to be measured 12 in the container 41, and the electrochemical sensor F is electrically connected to a computer 54 via a lead wire. The computer 54 has a monitor 55.
[0069]
The liquid to be measured 12 in the container 41 is brought close to the flow velocity of the liquid to be measured 12 in the material to be measured 11 by artificially generating a water flow using a pump as necessary.
[0070]
Further, the electrochemical sensor F is provided with a test piece b, a reference electrode c, and a reference test piece d, all of which are made of the same material as the material 11 to be measured. However, the test piece b may be made of platinum.
[0071]
Here, the terminal of the computer 14 and the terminal of the computer 54 are connected via a network 56.
[0072]
First, the corrosion potential E is measured between the test piece b and the reference electrode c provided in the electrochemical sensor F of the corrosion environment monitoring device 1B, and at the same time, between the test piece b and the reference test piece d provided in the electrochemical sensor F. The corrosion current i is measured.
[0073]
Further, the computer 14 calculates the potential standard deviation σ from the corrosion potential E and the corrosion current i according to the above-described equations (1) and (2)._EAnd current standard deviation σ_iIs calculated,
(Equation 4)
R = σ_E/ Σ_i
Is calculated from the relationship. At the same time, a calibration curve representing the relationship between the corrosion resistance R and the corrosion rate is created by actually measuring the change in the test piece weight as the corrosion rate.
[0074]
Further, by repeating the operation of preparing various calibration curves corresponding to various combinations of the material to be measured 11 and the various liquids to be measured 12, a group of calibration curves representing the relationship between the corrosion resistance R and the corrosion rate is prepared. Then, it is stored in the computer 14 as a database.
[0075]
Subsequently, by setting and inputting the material and form of the material to be measured 11, the liquid quality, liquid temperature, and flow velocity of the liquid to be measured 12 to the computer 54 of the corrosive environment monitoring device 1 </ b> B, measurement is performed from the prepared calibration curve group. Extract the calibration curve corresponding to the condition.
[0076]
Next, similarly to the operation of the corrosive environment monitoring device 1 of FIG._EAnd current standard deviation σ_iIs calculated.
[0077]
Next, the computer 14 shown in FIG._EAnd current standard deviation σ_iFrom the corrosion resistance R.
[0078]
Further, data on the calculated corrosion resistance R is transmitted from the computer 14 to the computer 54 via the network 56.
[0079]
Finally, the transmitted corrosion resistance R is referred to the extracted calibration curve, and the corrosion rate obtained by reference is displayed on the monitor 55, so that the corrosion environment of the measurement liquid 12 in the measurement target material 11 can be measured. Without directly measuring the corrosion rate, it is possible to accurately and accurately estimate the constantly changing corrosion state of the workpiece 11.
[0080]
Further, as a test piece b of the electrochemical sensor A and the electrochemical sensor F provided in the corrosion environment monitoring device 1B of FIG. 6, a stress test piece b1 shown in FIG. 3A or a stress test piece shown in FIG. The corrosion rate of the liquid 12 to be measured is displayed using b2. That is, by evaluating the change in the corrosion rate in the corrosive environment, the state of the stress corrosion cracking of the measured material 11 having the residual stress can be accurately and accurately estimated.
[0081]
In addition, as a test piece b of the electrochemical sensor A and the electrochemical sensor F provided in the corrosive environment monitoring device 1B of FIG. 6, a corrosion test piece b3 shown in FIG. Is displayed. That is, by evaluating the change in the corrosion rate in the corrosive environment, the state of crevice corrosion of the workpiece 11 having the crevice structure can be accurately and accurately estimated.
[0082]
As described above, according to the corrosion environment monitoring device 1B of FIG. 6, it is possible to accurately and accurately estimate and display the corrosion state of structures, devices, and pipes from the constantly changing corrosion rate.
[0083]
FIG. 7 is a schematic view showing a fourth embodiment of the corrosion environment monitoring device according to the present invention.
[0084]
In the corrosion environment monitoring device 1C, the liquid to be measured 12 is supplied into the material to be measured 11. An electrochemical sensor A is immersed in the liquid to be measured 12, and the electrochemical sensor A is electrically connected to a computer 14 via a lead wire. The computer 14 has a monitor 15.
[0085]
In addition, the electrochemical sensor A is provided with a reference electrode c and a reference test piece d, and both the reference electrode c and the reference test piece d are made of a material equivalent to the material to be measured 11.
[0086]
Further, in the corrosive environment monitoring device 1C, in order to measure a signal of the material 11 itself, the material 11 is electrically connected to the computer 15 via a lead wire.
[0087]
First, the corrosion potential E is measured between the measured material 11 of the corrosive environment monitoring device 1C and the reference electrode c provided on the electrochemical sensor A, and at the same time, the corrosion potential E of the measured material 11 and the reference test piece d provided on the electrochemical sensor A is measured. The corrosion current i is measured in between.
[0088]
Next, the computer 14 calculates the potential standard deviation σ according to the predetermined time width from the corrosion potential E and the corrosion current i by the above-described formulas 1 and 2._EAnd current standard deviation σ_iIs calculated.
[0089]
Finally, the calculated potential standard deviation σ_EAnd current standard deviation σ_iIs displayed on the monitor 15 and the variation due to the change in the corrosive environment is evaluated based on the variation due to the noise of the signal and the variation due to the unevenness of the corrosion.
[0090]
As described above, according to the corrosive environment monitoring device 1C of FIG. 7, an electrical signal indicating a change in corrosive environment is measured, and by considering the variation of this signal, corrosion damage of structures, equipment, and piping is reduced. Guess and display accurately and accurately.
[0091]
Further, by directly obtaining corrosion information from the material to be measured, it is possible to accurately and accurately estimate and display the corrosion state of structures, equipment, and piping.
[0092]
FIG. 8 is a schematic diagram showing a fifth embodiment of the corrosion environment monitoring device according to the present invention.
[0093]
In the corrosive environment monitoring device 1D, the measured liquid 12 is supplied into the container 41. An electrochemical sensor F is immersed in the liquid to be measured 12 in the container 41, and the electrochemical sensor F is electrically connected to the computer 14 via a lead wire.
[0094]
The liquid 12 to be measured in the container 41 is brought close to the flow rate of the liquid 12 to be measured in the material 11 to be measured by artificially generating a water flow using a pump as necessary.
[0095]
In addition, the electrochemical sensor F includes a test piece b, a reference electrode c, and a reference test piece d, all of which are made of the same material as the material 11 to be measured. However, the test piece b may be made of platinum.
[0096]
In FIG. 8, the same parts as those in FIG. 7 are denoted by the same reference numerals, and description thereof will be omitted.
[0097]
First, the corrosion potential E is measured between the test piece b and the reference electrode c provided in the electrochemical sensor F of the corrosion environment monitoring device 1D, and at the same time, between the test piece b and the reference test piece d provided in the electrochemical sensor F. The corrosion current i is measured.
[0098]
Further, the computer 14 calculates the potential standard deviation σ from the corrosion potential E and the corrosion current i according to the above-described equations (1) and (2)._EAnd current standard deviation σ_iIs calculated,
(Equation 5)
R = σ_E/ Σ_i
Is calculated from the relationship. At the same time, a calibration curve representing the relationship between the corrosion resistance R and the corrosion rate is created by actually measuring the change in the test piece weight as the corrosion rate.
[0099]
Furthermore, by repeating the operation of preparing various calibration curves so as to correspond to various combinations of the material to be measured 11 and the various solutions to be measured 12, a calibration curve group representing the relationship between the corrosion resistance R and the corrosion rate is obtained. It is prepared and stored in the computer 14 as a database.
[0100]
Subsequently, by setting and inputting the material and form of the material to be measured 11, the liquid quality, liquid temperature, and flow velocity of the liquid to be measured 12 to the computer 14 of the corrosive environment monitoring device 1 </ b> D, measurement is performed from the prepared calibration curve group. Extract the calibration curve corresponding to the condition.
[0101]
Next, similarly to the operation of the corrosion environment monitoring device 1C in FIG._EAnd current standard deviation σ_iIs calculated.
[0102]
Next, the computer 14 of FIG._EAnd current standard deviation σ_iFrom the corrosion resistance R.
[0103]
Finally, the calculated corrosion resistance R is referred to the extracted calibration curve, and the corrosion rate obtained by referring to the reference is displayed on the monitor 15 so that the corrosion environment of the test liquid 12 in the test object 11 can be measured. Without directly measuring the corrosion rate, it is possible to accurately and accurately estimate the constantly changing corrosion state of the workpiece 11.
[0104]
In FIG. 8, the electrochemical sensor A and the electrochemical sensor F are connected to the computer 14 at the same time. However, after the electrochemical sensor F is connected to the computer 14 and the computer 14 creates a database, the electrochemical After disconnecting the sensor F, the computer 14 may be connected to the electrochemical sensor A.
[0105]
As described above, the corrosion environment monitoring device 1D in FIG. 8 can accurately and accurately estimate and display the corrosion state of structures, equipment, and pipes from the constantly changing corrosion rate.
[0106]
Further, by directly obtaining corrosion information from the material to be measured, it is possible to accurately and accurately estimate and display the corrosion state of structures, equipment, and piping.
[0107]
FIG. 9 is a schematic view showing a sixth embodiment of the corrosion environment monitoring device according to the present invention.
[0108]
The corrosion environment monitoring device 1E of FIG. 9 differs from the corrosion environment monitoring device 1D of FIG. 8 in that a computer that stores a calibration curve group prepared in advance as a database is different from a computer in which corrosion potential and corrosion current are measured. This is a system that monitors the corrosion status of structures, equipment, and piping with a computer at a location away from the measurement site.
[0109]
In the corrosive environment monitoring device 1E, the liquid to be measured 12 is supplied into the material to be measured 11. An electrochemical sensor A is immersed in a liquid to be measured 12 in a material to be measured 11, and the electrochemical sensor A is electrically connected to a computer 14 via a lead wire.
[0110]
In addition, the electrochemical sensor A is provided with a reference electrode c and a reference test piece d, and both the reference electrode c and the reference test piece d are made of a material equivalent to the material to be measured 11.
[0111]
On the other hand, in the corrosive environment monitoring device 1E, the measured liquid 12 is supplied into the container 41. The electrochemical sensor F is immersed in the liquid to be measured 12 in the container 41, and the electrochemical sensor F is electrically connected to a computer 54 via a lead wire. The computer 54 has a monitor 55.
[0112]
The liquid to be measured 12 in the container 41 is brought close to the flow velocity of the liquid to be measured 12 in the material to be measured 11 by artificially generating a water flow using a pump as necessary.
[0113]
Here, the terminal of the computer 14 and the terminal of the computer 54 are connected via a network 56.
[0114]
First, the corrosion potential E is measured between the test piece b and the reference electrode c provided in the electrochemical sensor F of the corrosion environment monitoring device 1E, and at the same time, between the test piece b and the reference test piece d provided in the electrochemical sensor F. The corrosion current i is measured.
[0115]
Further, the computer 14 calculates the potential standard deviation σ from the corrosion potential E and the corrosion current i according to the above-described equations (1) and (2)._EAnd current standard deviation σ_iIs calculated,
(Equation 6)
R = σ_E/ Σ_i
Is calculated from the relationship. At the same time, a calibration curve representing the relationship between the corrosion resistance R and the corrosion rate is created by actually measuring the change in the test piece weight as the corrosion rate.
[0116]
Further, by repeating the operation of preparing various calibration curves corresponding to various combinations of the material to be measured 11 and the various liquids to be measured 12, a group of calibration curves representing the relationship between the corrosion resistance R and the corrosion rate is prepared. Then, it is stored in the computer 14 as a database.
[0117]
Subsequently, by setting and inputting the material and form of the material to be measured 11, the liquid quality, liquid temperature, and flow velocity of the liquid to be measured 12 into the computer 54 of the corrosive environment monitoring device 1 </ b> E, measurement is performed from the prepared calibration curve group. Extract the calibration curve corresponding to the condition.
[0118]
Next, similarly to the operation of the corrosive environment monitoring device 1C of FIG._EAnd current standard deviation σ_iIs calculated.
[0119]
Next, the computer 14 shown in FIG._EAnd current standard deviation σ_iFrom the corrosion resistance R.
[0120]
Further, data on the calculated corrosion resistance R is transmitted from the computer 14 to the computer 54 via the network 56.
[0121]
Finally, the transmitted corrosion resistance R is referred to the extracted calibration curve, and the corrosion rate obtained by reference is displayed on the monitor 55, so that the corrosion environment of the measurement liquid 12 in the measurement target material 11 can be measured. Without directly measuring the corrosion rate, it is possible to accurately and accurately estimate the constantly changing corrosion state of the workpiece 11.
[0122]
As described above, according to the corrosion environment monitoring device 1E of FIG. 9, it is possible to accurately and accurately estimate and display the corrosion state of structures, devices, and pipes from the constantly changing corrosion rate.
[0123]
Further, by directly obtaining corrosion information from the material to be measured, it is possible to accurately and accurately estimate and display the corrosion state of structures, equipment, and piping.
[0124]
FIG. 10 is a state diagram showing a selection screen of measurement conditions of the corrosion environment monitoring device.
[0125]
FIG. 10 shows a measurement condition input screen 61 displayed on the monitor 15 provided in the computer 14 or the monitor 55 provided in the computer 54 when a calibration curve corresponding to a measurement condition is extracted from a calibration curve group as a database. .
[0126]
The measurement conditions include the material to be measured and the liquid to be measured. Furthermore, the material to be measured has a material and a form, and the liquid to be measured has a liquid quality, a liquid temperature, and a flow rate, and is a format that can be easily selected from options. Other measurement conditions include a measurement channel and a measurement interval, and a display method.
[0127]
First, the measurer selects the material to be measured and the solution to be measured from the options before measuring the corrosive environment of the solution to be measured, and calculates a calibration curve corresponding to the measurement conditions of the combination of the material to be measured and the solution to be measured. Extract.
[0128]
Further, other measurement conditions are determined by selecting a measurement channel and a measurement interval.
[0129]
Finally, a display method to be displayed on the monitor 15 or the monitor 55 is selected.
[0130]
The number and configuration of the measurement conditions can be changed as needed.
[0131]
【The invention's effect】
As described above, by measuring an electrical signal indicating a change in a corrosive environment and considering the variation in the signal, it is possible to accurately and accurately estimate and display corrosion damage to structures, equipment, and piping.
[0132]
In addition, the corrosion state of structures, equipment, and piping can be accurately and accurately estimated and displayed from the corrosion rate that changes every moment.
[0133]
Further, by directly obtaining corrosion information from the material to be measured, it is possible to accurately and accurately estimate and display the corrosion state of structures, equipment, and piping.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a first embodiment of a corrosion environment monitoring device according to the present invention.
FIG. 2 is a schematic graph showing an example of potential fluctuation and current fluctuation.
3A is a configuration diagram illustrating an example of a stress test piece, and FIG. 3B is a configuration diagram illustrating an example of a stress test piece.
FIG. 4A is a front view illustrating an example of a gap test piece, and FIG. 4B is a side view illustrating an example of a gap test piece.
FIG. 5 is a schematic diagram showing a second embodiment of the corrosion environment monitoring device according to the present invention.
FIG. 6 is a schematic view showing a third embodiment of the corrosion environment monitoring device according to the present invention.
FIG. 7 is a schematic view showing a fourth embodiment of the corrosion environment monitoring device according to the present invention.
FIG. 8 is a schematic view showing a fifth embodiment of the corrosion environment monitoring device according to the present invention.
FIG. 9 is a schematic view showing a sixth embodiment of the corrosion environment monitoring device according to the present invention.
FIG. 10 is a schematic diagram showing a screen for selecting measurement conditions of the corrosive environment monitoring device.
[Explanation of symbols]
1,1A, 1B, 1C, 1D, 1E corrosion environment monitor
11 Material to be measured
12 Liquid to be measured
14 Computer
15 monitor
21 ° potential fluctuation
22 current fluctuation
23 ° expansion potential fluctuation
24 power fluctuation
30 flat plate or disk
31 bolt
32 nut
33 fixing jig
35 flat plate or disk
36mm auxiliary plate or disk
37mm bolt
38 nut
41 container
54 computer
55 monitor
56 network
61 input screen
A Electrochemical sensor
b Test piece
b1 Stress test piece
b2 stress test piece
b3 Clearance test piece
c Reference electrode
d Reference specimen
F electrochemical sensor

Claims (9)

The water flowing in the plant is the liquid to be measured, and the plant structural material in contact with the liquid to be measured is the material to be measured.In order to estimate the corrosion damage of the material to be measured, the corrosion detected from the liquid to be measured is In a corrosive environment detecting method for detecting a change in a potential E and a corrosion current i as a change in a corrosive environment of the liquid to be measured,
Calculating a potential standard deviation σ _E according to a predetermined time width of the corrosion potential E;
Calculating a current standard deviation σ _i according to a predetermined time width of the corrosion current i;
Estimating a change in the corrosion environment of the liquid to be measured from the potential standard deviation and the current standard deviation by displaying changes in the potential standard deviation and the current standard deviation on a monitor, respectively. And corrosive environment monitoring method. A corrosion resistance R (R = σ _E / σ _i ) is calculated from the potential standard deviation and the corrosion current standard deviation, and the corrosion resistance R is prepared in advance using various test pieces and various liquids to be measured. 2. The method according to claim 1, wherein a change in the corrosion environment of the liquid to be measured is estimated from the corrosion rate obtained by referring to a calibration curve representing the relationship between the corrosion resistance R and the corrosion rate stored in a computer. Corrosion environment monitoring method. The water flowing in the plant is used as the liquid to be measured, and the plant structural material in contact with the liquid to be measured is used as the material to be measured. In order to estimate corrosion damage of the material to be measured, the corrosion potential E of the liquid to be measured is measured. For a corrosion environment detection device connected to a measurement processing device via a lead wire from an electrochemical sensor including a test piece and a reference test piece for measuring corrosion current i, while having a test piece and a reference electrode,
Using a computer as the measurement processing device;
A function of calculating a potential standard deviation σ _E of the corrosion potential by a predetermined time width;
A function of calculating the current standard deviation σ _i of the corrosion current by a predetermined time width;
A monitor for corrosive environment, wherein the computer includes a monitor for displaying changes in the potential standard deviation and the current standard deviation. The computer has a function of calculating the corrosion resistance R (R = σ _E / σ _i ) from the potential standard deviation and the current standard deviation, and a calibration curve group representing the relationship between the corrosion resistance R and the corrosion rate as a database. A function of storing, a function of extracting a calibration curve corresponding to a material to be measured and a solution to be measured from the calibration curve group, and a function of estimating the corrosion rate by comparing the calculated corrosion resistance R with the calibration curve. The corrosion environment monitoring device according to claim 3, further comprising: The electrochemical sensor is provided with a reference electrode for measuring corrosion potential, while a reference test piece is provided for measuring corrosion current, connected to a computer via a lead wire from the electrochemical sensor, and read from a material to be measured. The corrosion environment monitoring device according to claim 3, wherein the device is connected to a computer via a wire. The corrosion environment monitoring device according to claim 3, wherein the test piece has a structure in which a stress is applied by applying a static strain. The corrosion environment monitoring device according to claim 3, wherein the test piece has a gap structure. The corrosion environment monitoring device according to claim 4, wherein the computer is a first computer, and a terminal of the first computer and a terminal of a second computer at a remote place are connected by a network system. 5. The corrosive environment monitoring apparatus according to claim 4, wherein said computer is provided with interactive software for inputting a material to be measured, a liquid to be measured, and other measurement conditions.

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