• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Sensor for the monitoring of corrosión by means of impedance and electrochemical noise measurements and resistance to polarization and use thereof. In the present invention, a sensor capable of performing joint measurements of impedance and electrochemical noise and resistance to polarization is presented, which allows a reliable and continuous control, both of the generalized corrosión processes and of localized corrosión. This monitoring system is suitable for industrial or process atmospheres, both at low and high temperature in which a molten, gaseous or liquid phase is present, either, for example, from metals, alloys, salts or glasses, all they in the molten state. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2573178A1
    申请号:ES201500674
    申请日:2015-09-18
    公开日:2016-06-06
    发明作者:Héctor SANTOS BARAHONA；María Teresa DE MIGUEL GAMO；María Isabel LASANTA CARRASCO；Gustavo GARCÍA MARTÍN；Francisco Javier PÉREZ TRUJILLO
    申请人:Universidad Complutense de Madrid；
    IPC主号:
    专利说明:

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    DESCRIPTION
    Sensor for corrosion monitoring by means of electrochemical measurements and noise resistance and resistance to polarization and its use.
    Technology Sector
    The present invention relates to a sensor for carrying out electrochemical measurements of impedance and noise, as well as polarization resistance, being able to evaluate, through these measures, the development of the corrosion of one or several materials exposed to different corrosive atmospheres in the field. industrial, both low and high temperature. In the latter case, more specifically, this monitoring system is appropriate for industrial or process atmospheres in which a molten, gaseous or liquid phase is present, either, for example, from metals. alloys, salts or glasses, all of them in molten state.
    State of the art
    Corrosion that occurs in industrial equipment is one of the main causes of loss of productive availability as well as increased costs associated with operational maintenance. In this sense, it is crucial to incorporate into the plant control systems tools or criteria that facilitate decision making, particularly as regards the synchronization of the scheduled procedures for stopping, repairing and replacing different units or parts of the installation.
    The most conventional technique, which is still used until today, is the exposure of corrosion witnesses to the corrosive medium. The witnesses are inspected and analyzed periodically determining their weight loss, from which a generalized corrosion rate is calculated. They are also examined by microscope to identify possible points of localized corrosion. This method involves investing a considerable amount of time and does not allow to determine exactly the temporal evolution of the corrosion since it is not possible to operate the corrosion controls frequently enough.
    WO2005 / 054821 describes a system for measuring corrosion based on another conventional technique such as electrical resistance. It presents a system formed by a rectangular metallic element of known dimensions, exposed to a corrosive atmosphere and connected with an electrical resistance measurement system and that also includes a temperature sensor and a pressure sensor that allow these two to be monitored variables The invention is based on the determination of corrosion in the relationship between the electrical resistance of the element and its mass.
    Document US3772178 describes an electrode manufactured in the form of a solid metal rod with a threaded end that allows its attachment to a metal base electrically connected with a measuring system. The system is designed to include three electrodes of this type that will have the same surface and surface characteristics, with the objective of monitoring corrosion by means of electrical polarization measurements.
    The GB2006437 patent presents a system formed by a cell that will contain a corrosive liquid, a piece of metal with a known surface that will work as a working electrode, a reference electrode and a system capable of generating a
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    electric current. A method of determining the corrosion of the metal based on the anodic and cathode Tafel slopes is also described, from which the corrosion current density is obtained and, from the latter, the corrosion rate can be calculated .
    The main drawback of all the previously described techniques is that they can only give reliable information on generalized corrosion, so that, in the event of localized corrosion, the system cannot detect it.
    In WO02056035 a sensor is presented to monitor corrosion in industrial equipment by means of electrochemical measurements, which is composed of two electrodes and two conductive wires embedded in a pure epoxy resin. The epoxy resin provides the necessary electrical insulating characteristics; however, the sensitivity of the sensor depends on the atmosphere and point of the industrial plant where corrosion monitoring is required.
    Despite all the systems that have been developed to monitor the corrosion of industrial equipment, there is still a need for systems that provide reliable and continuous information about the corrosive processes that occur in industrial equipment.
    In the present invention, a sensor capable of performing joint measurements of electroqulmic noise and impedance and resistance to polarization is presented, which allows reliable and continuous control of both generalized and localized corrosion processes.
    Detailed description of the invention
    Corrosion monitoring sensor by electrochemical measurements of impedance and noise and resistance to polarization.
    The sensor (Figure 1) comprises at least two electrodes (1) of the same metallic material (a primary and a secondary electrode), a conducting wire (6) for each electrode consisting of a conductive metal matrix, a thermocouple (2) located on the front of the sensor, a filler matrix (3) where the previous elements are embedded, an internal sheath (4) that provides the structure to the sensor and whose interior houses the previous elements, and an external sheath (5) protective inside whose elements described above are housed. Optionally, the sensor can include an integrated and independent refrigeration system. Likewise, the sensor can also contain a sample holder system that acts as corrosion test specimens.
    The electrodes (1) consist of a single metal material, the same as that of the monitored plant equipment.
    The thermocouple (2) is arranged along the longitudinal axis of the sensor in order to achieve a reliable recording of the temperature of the electrodes, verifying the correspondence with the operating conditions of interest. The incorporation of the thermocouple into the corrosion sensor provides advantages, both from the point of view of the corrosion monitoring and from the purely operational point of view, since it allows to control temperature differences from one point to another of the installation, as well as
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    disturbances that may occur at the same point throughout the operation time. Especially, it allows, in turn, to control temperature transients that may affect the corrosive potential. From the point of view of the operation of the industrial installation, it provides, in turn, the possibility of controlling the temperature at points where there is no temperature control instrumentation.
    The core of the sensor body is constituted by a filler matrix (3), in order to avoid electrical contact between the conductive wires and the thermocouple that run through the sensor. Said filler matrix is constituted by electrically insulating material, such as ceramic oxide-based material. for example, aluminosilicate.
    To the insulating material of the filler matrix (3), a compound that provides electrical conductivity can be added as an additive to improve the sensitivity of the sensor during the measurements of the properties of interest (electrochemical impedance and noise, as well as resistance to polarization). This material is added to the surface exposed to the medium where the measurement is made. Preferably, but not limited to, the additive added will be graphite-based particles of a size in the range 0.1-45 pm and will be added during the preparation of the insulating filler in the range of 0.1-10% by weight for a certain length and, therefore, sensor body volume. This length and, therefore, the volume of the sensor body that incorporates filling of insulating material with the additive, in order to improve the sensitivity of the sensor in the electrochemical measurements of impedance and noise, can vary from one millimeter from the last section of the matrix. filling-insulator "to cover the entire length of the sensor body. The "last section of the filler matrix" is defined as the section of the sensor body located on the front of the sensor and which, together with the surface of the electrodes. it gives rise to the surface in contact with the corrosive atmosphere. Depending on the location on the floor of the sensor and the need to increase the sensitivity of the measurements, in each specific application, the length and, therefore, volume of the sensor body to be filled with insulating material added with the additive will be defined. Improve sensor sensitivity.
    The specific composition of the filler matrix (3) must be such that it minimizes any phenomenon of total or partial dissolution of the filler matrix within the operating fluid of interest, particularly in high or very high temperature processes, in the presence of fluid phases such as metals, alloys, salts or glasses, all of them in the molten state.
    This filler matrix is contained by an internal sheath (4) of an electrical insulating material, for example. Ceramic based.
    To adapt this sensor to the conventional and analogue insertion ports, another external sheath (5) consisting of metallic materials is arranged on the internal sheath (4) in order to give the sensor sufficient mechanical entity to allow its manipulation and installation in the ports of insertion and analogs using for this, for example, a conventional flange joint. The function of this coverage or external sheath is to provide the mechanical resistance sensor for use in any environment. The sensor described in this invention can be placed in industrial equipment where it will frequently be exposed to weather conditions such as rain, wind, vibrations of the equipment itself, etc., so it is extremely important to provide sufficient structural integrity to ensure your durability for long periods of time.
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    The electrodes are connected to the rest of the auxiliary riding by means of respective conductive wires (6) that run the sensor longitudinally. The conductive wires extend from the base of the electrodes until they completely cross the sensor body, leaving a part of them outside to allow the connection by cables to the auxiliary equipment (more specifically, a potentiostat) for electrochemical measurements and noise impedance , in addition to resistance to polarization. During the tests of these properties of interest, the electrical signal generated by the potentiostat circulates through the conductive wires to the surface of the electrodes in contact with the corrosive medium and through them, likewise, the electrical signal generated in response is collected.
    The sensor that describes the present invention is applicable to both process media with low operating temperatures and with high and very high temperatures. In the latter case, in particular, the monitoring system is appropriate for industrial or process atmospheres in which a fluid, gaseous or liquid phase is present, either, for example, from metals, alloys, salts or glasses. , all of them in molten state.
    In another application of this invention, the sensor can be used for the selection between different materials, proceeding to the comparative monitoring of the corrosion of the materials of interest when exposed to a certain corrosive atmosphere and at a certain temperature. In this particular case the sensor will have as many sets of primary and secondary electrodes as materials to be evaluated in a given corrosive atmosphere.
    In another particular embodiment, the sensor may also have in its head a sample holder system that acts as corrosion test specimens.
    Brief description of the figures
    Figure 1 illustrates a longitudinal section of a general embodiment of the sensor for corrosion monitoring.
    Figure 2 illustrates a cross-section of a particular embodiment of the sensor shown in Figure 1, embodiment oriented to the monitoring of the corrosion of several metals in parallel.
    Figure 3 illustrates a cross-section of a particular embodiment of the sensor for insertion of a set of corrosion test specimens.
    Figure 4 illustrates a longitudinal section of a particular embodiment of the sensor for monitoring the corrosion of several materials in parallel at high temperature, including both a variant of external (A) and internal (B) refrigeration, according to the particular needs of each monitored installation, as well as according to the practical possibilities of adapting the sensor to the available insertion port.
    Figure 5 shows the electrochemical impedance curve EIS obtained with the claimed sensor immersed in a mixture of molten salts. The data in this graph is adjusted to a particular circuit that corresponds to the corrosion mechanism by porous layer.
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    Mode of realization of the invention
    The present invention is further illustrated by the following examples, which are not intended to be limiting in scope.
    Example 1
    This example shows a particular mode of realization of the invention that allows the monitoring of the corrosion of several materials in parallel.
    In this particular case, the sensor has two sets of primary and secondary electrodes to evaluate two materials in a given corrosive atmosphere.
    Figure 2 shows, both a detail of the cross-section (A) and the longitudinal section (B), of the sensor head, that is, the front part that is inserted into the operating means of interest. Both the primary and secondary electrodes must have the same dimensions, since either will work as a working electrode and either will work as a reference and auxiliary electrode together. It is necessary, therefore, that the electrodes have the same dimensions and the sensor symmetry be maintained.
    The distribution of the electrodes, with respect to the rest of the sensor section in contact with the corrosive medium of interest, will be such that possible condensations of the atmosphere, in this case based on steam or gas, on the surface of the electrodes are minimized . This particular embodiment is optimal for reducing the errors induced in electrochemical measurements, as well as in the measure of polarization resistance. In the event that the corrosive medium of interest is liquid, it is convenient to increase the length of the electrodes in order to separate their front part of the sensor body, optimizing the measurement of the properties of interest.
    As a particular design alternative (Figure 28), they can be applied around the conducting wires. a modular series of hollow cylindrical pieces that act as modular electrical insulators (7), of analogous composition to the inner sheath (4), allowing the dosing of the insulating matrix (3) to be made more flexible. The latter is of special interest in the case of having particular variants of sensor design that include an internal refrigeration system.
    Example 2
    This example shows a particular case of realization of the invention where the sensor head contains a sample holder system that acts as corrosion test specimens.
    In Figure 3 it is shown. both a detail of the cross-section (A) and the longitudinal section (B) of a sensor that has six test tubes (8) for the corrosion controls so that these corrosion controls (materially identical to the material of interest) are fixed by means of a threaded connection, conveniently insulated, to the holder, the base of these is embedded in the filler matrix (3). In the case of the variant (A), a typical application of the modular elements (7) is included.
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    Example 3
    This example refers to a particular sensor design oriented to high temperature applications.
    For this, two variants of the independent and exclusive sensor cooling system design (9) are incorporated, and may be auxiliary for possible refrigeration systems present in the monitored installation itself. Figure 4 shows these two variants: an exterior refrigeration variant (A) and an internal refrigeration variant (B), applicable according to the needs of complementary refrigeration as well as according to the limitations in the adaptation of the sensor to the equipment of interest.
    Example 4
    This example refers to the average obtained with the described sensors.
    Figure 5 shows the electrochemical impedance (EIS) curve obtained in a titanium corrosion test for 100 hours with the sensor immersed in molten sulfate-chloride based molten salts.
    The curve is composed of a very small semi-circle at high frequencies followed by a straight to low frequencies, which means that the corrosion process is very accelerated and that the limiting stage is the diffusion of the species in the double layer.
    The data obtained in the EIS curve can be adjusted with the following equivalent circuit:
    image 1
    Where Re is the electrolyte resistance, Cdl is a double layer capacitance, Rt is the resistance to charge transfer and W is Warburg resistance.
    权利要求:
    Claims (13)
    [1]
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    1. Corrosion monitoring sensor comprising:
    - at least, a primary electrode and a secondary electrode for the measurement of impedance and electrochemical noise and polarization resistance, composed of the same metallic material as that of the monitored equipment.
    - a conductive wire for each electrode,
    - a thermocouple arranged along the longitudinal axis of the sensor,
    - a filler matrix where the previous elements are embedded,
    - an internal sheath whose interior houses the previous elements and
    - an outer protective sheath that houses the previous elements.
    [2]
    2. Corrosion monitoring sensor, according to claim 1, wherein the filler matrix is constituted by electrically insulating material such as oxide-based ceramic materials, for example, aluminosilicate.
    [3]
    3. Corrosion monitoring sensor, according to previous claims, where a compound that provides electrical conductivity to improve the sensitivity of the sensor is added to the filler matrix.
    [4]
    4. Corrosion monitoring sensor, according to claim 3, where the additive is graphite based particles of a size between 0.1 and 45 pm.
    [5]
    5. Corrosion monitoring sensor according to claims 3 and 4, wherein the additive is added to the insulating filler matrix in a proportion between 0.1 and 10% by weight.
    [6]
    6. Corrosion monitoring sensor, according to claim 1, wherein the inner sheath is made of a thermal insulating material, for example, based on ceramics.
    [7]
    7. Corrosion monitoring sensor, according to claim 1, where the external sheath is made of metal materials.
    [8]
    8. Corrosion monitoring sensor, according to claim 1, where the conductive wires are connected by cables to auxiliary equipment to the sensor.
    [9]
    9. Corrosion monitoring sensor, according to claim 8, where the auxiliary equipment is a potentiostat.
    [10]
    10. Corrosion monitoring sensor according to claim 1, which also includes test tubes for corrosion controls.
    [11]
    11. Corrosion monitoring sensor, according to any of the preceding claims, further comprising a refrigeration system.
    [12]
    12. Corrosion monitoring sensor, according to previous claims, where the electrodes have the same dimensions and the sensor symmetry is maintained.
    5 13. Use of the claimed sensor for local corrosion monitoring in installations
    Industrial
    [14]
    14. Use of the sensor claim, according to claim 10, as a corrosion control.
    10 15. Use of the claimed sensor, according to claim 12, for monitoring
    Comparison of corrosion of different materials.
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US4196057A|1978-08-31|1980-04-01|Petrolite Corporation|Cold end corrosion rate probe|
    US20050212534A1|2002-06-17|2005-09-29|Cottis Robert A|Method and apparatus for monitoring corrosion|
    CN202471565U|2012-03-14|2012-10-03|东北石油大学|High temperature and high pressure H2S/CO2 corrosion reaction device capable of realizing dynamic electrochemical test|
    CN103149146A|2013-02-01|2013-06-12|厦门大学|Multifunctional corrosion monitoring probe used for monitoring corrosion of industrial equipment|CN114046874A|2022-01-11|2022-02-15|中国空气动力研究与发展中心高速空气动力研究所|Test device for measuring supersonic jet near-field noise|JPH0318112B2|1982-02-26|1991-03-11|Furiidoritsuhi Uiruerumu Eruhaosu|
    JP5087503B2|2008-09-05|2012-12-05|川崎重工業株式会社|Corrosion monitoring sensor|
    US8298390B2|2008-11-26|2012-10-30|Xiaodong Sun Yang|Electrochemical probes for corrosion monitoring in hydrogen sulfide systems and methods of avoiding the effect of electron-conducting deposits|RU182291U1|2017-12-28|2018-08-13|АО "Интер РАО - электрогенерация"|DEVICE FOR CONTROL OF CHANGE DURING OPERATION OF THE CORROSION STATE OF THE SURFACE OF A COAT-AND-TUBE STEAM-AND-TUBE HEAT EXCHANGER ON THE STEAM SIDE|
    法律状态:
    2017-07-31| FG2A| Definitive protection|Ref document number: 2573178 Country of ref document: ES Kind code of ref document: B2 Effective date: 20170731 |
    优先权:
    申请号 | 申请日 | 专利标题
    ES201500674A|ES2573178B2|2015-09-18|2015-09-18|Sensor for corrosion monitoring through electrochemical impedance and noise measurements and polarization resistance and use thereof|ES201500674A| ES2573178B2|2015-09-18|2015-09-18|Sensor for corrosion monitoring through electrochemical impedance and noise measurements and polarization resistance and use thereof|
    EP16845770.3A| EP3351924A4|2015-09-18|2016-09-12|Sensor for monitoring corrosion by means of measurements of electrochemical impedance and noise and of resistance to polarisation and use of same|
    PCT/ES2016/000097| WO2017046427A1|2015-09-18|2016-09-12|Sensor for monitoring corrosion by means of measurements of electrochemical impedance and noise and of resistance to polarisation and use of same|
    CL2018000715A| CL2018000715A1|2015-09-18|2018-03-16|Sensor for corrosion monitoring by means of electrochemical impedance and noise measurements and resistance to polarization and its use.|
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