Method for measuring orp of high temperature high pressure water in situ, sensor and method of processing thereof

Abstract

The application belongs to the field of electrochemical sensors, and discloses a method for in-situ measuring ORP value of high-temperature and high-pressure water, a sensor and a processing method thereof, wherein the sensor is composed of an electrode core body, an electrode support assembly, a sealing assembly and a reference electrode, and specifically comprises a sheet-shaped platinum electrode sheet, an electrode sheet flow guide hole, a sealing sintered material, a platinum wire, a sealing filler, an insulating sheath, an electrode sheath and an insulating ceramic, has the characteristics of stable chemical performance, high-temperature resistance and corrosion resistance, has a small solubility in a high-temperature and high-pressure aqueous solution system, and almost needs no maintenance. Since the sensor is a solid electrode structure, the structure is firm and the service life is long.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrochemical sensors, in particular, to a method for in-situ measuring ORP value of high-temperature and high-pressure water, a sensor and a processing method thereof. BACKGROUND

[0002] As one of the important indicators of water chemical system, oxidation-reduction potential (ORP) reflects the macroscopic oxidation-reduction of all substances in the system. The determination of oxidation-reduction potential has been widely used in nuclear power plants, thermal power plants, hydrometallurgy, geothermal chemistry, water treatment, soil environment monitoring, metal corrosion and resource exploration, etc. ORP can be used as a standard to evaluate the quality of water, and qualitatively evaluate the quality of reactor coolant water and the corrosion rate of system structure materials. Oxidation-reduction potential can be measured by ORP oxidation-reduction electrode, and obtained by measuring the potential between the electrode and the reference electrode. Although oxidation-reduction potential measurement is widely used in low-temperature and low-pressure environment, due to the limitation of high-temperature and high-pressure working electrode and reference electrode preparation technology and the lack of thermodynamic data in high-temperature and high-pressure water thermal system, the application of oxidation-reduction potential in high-temperature and high-pressure environment is relatively less.

[0003] The ORP sensor has been widely used in nuclear power plants for many years to control the amount of hydrogen generated to reduce intergranular stress corrosion cracking of reactor water and high-pressure feedwater reactor. The coolant of nuclear reactor is high-temperature and high-pressure water. The physical and chemical properties of water at high temperature and high pressure change greatly compared with those at normal temperature. Especially under supercritical conditions, the properties of water such as density and dielectric constant are significantly different from those at normal temperature. If the traditional online sampling, cooling and then sending to chemical instrument monitoring process is adopted, the water quality of water sample may have changed when it reaches the monitoring instrument, which cannot reflect the actual situation of water quality in time. If the ORP sensor can be used in high-temperature and high-pressure water, the ORP value of high-temperature and high-pressure solution can be monitored in-situ and in real time by high-temperature and high-pressure ORP detector, which can capture the change of water quality caused by any instantaneous change of coolant, reflect and control the oxidation-reduction condition of the system in time, thereby reducing the corrosion degree of the loop and the migration of corrosion products, and having important significance for understanding the corrosion behavior of materials in high-temperature and high-pressure water.

[0004] Due to the limitation of technical problems, the use environment of all ORP sensors in China is currently under low-temperature and low-pressure conditions. The glass electrode made of quartz glass material has a small wall thickness of the glass sensing end in contact with the test solution, which limits the pressure-bearing and temperature-resistant capacity of the ORP electrode, and the ORP electrode can only be used in test solutions below 75℃.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] The technical problem to be solved by the present application is that the existing ORP measurement technology is not suitable for online real-time monitoring of the ORP value of high-temperature and high-pressure solution.

[0007] The present application is implemented by the following technical solutions:

[0008] In one aspect, the present application provides a sensor for in-situ measurement of ORP value of high-temperature and high-pressure water, comprising a working electrode and a reference electrode, wherein the working electrode and the reference electrode are connected by a capillary; the working electrode comprises a platinum electrode sheet, an electrode lead, an electrode support and an electrode sheath; the platinum electrode sheet is provided with a plurality of flow guide holes; one end of the electrode lead is welded to one end of the platinum electrode sheet; a through hole is arranged in the electrode support along the length direction; the other end of the electrode lead passes through the through hole; one end of the platinum electrode sheet close to the electrode support is fixedly connected to the electrode support; the electrode sheath is arranged outside the part of the electrode lead that passes through the through hole; one end of the electrode sheath is fixedly connected to the end of the electrode support away from the platinum electrode sheet; an insulating layer is arranged between the inner wall of the electrode sheath and the outer wall of the electrode lead; a sealing assembly is arranged between the inner wall of the through hole and the outer wall of the electrode lead, between the end of the insulating layer close to the electrode support and the electrode lead, and outside the electrode sheath.

[0009] Further, the sealing assembly comprises a first sealing member, a second sealing member and a third sealing member; the first sealing member is filled between the inner wall of the through hole and the outer wall of the electrode lead; the second sealing member is filled between the end of the insulating layer close to the electrode support and the electrode lead; and the third sealing member is arranged outside the electrode sheath.

[0010] Further, the electrode lead is a platinum wire; the electrode support is made of Al2O3 insulating ceramic or zirconia ceramic; the insulating layer comprises an insulating temperature-resistant coating layer and an externally provided polytetrafluoroethylene heat-shrinkable tube; the first sealing member is a sealing mixed filler composed of a sealing sintered material and solder, and the sealing sintered material is selected from glass paste; the second sealing member is a sealing mixed filler composed of Al2O3 adhesive and Al2O3 sand; the third sealing member is obtained by co-pressing a graphite gasket through a flow cell and a flange mounted outside the electrode sheath; and the electrode sheath is made of C276 Hastelloy or 316L stainless steel material.

[0011] Further, the diameter of the flow guide hole is 1-3 mm, the sizes of the plurality of flow guide holes are different, and the platinum electrode piece comprises 2-5 flow guide holes; and the diameter of the through hole is 0.5 mm.

[0012] Further, the reference electrode is a solid-state reference electrode.

[0013] Further, the internal electrode of the reference electrode is made of a solid-state mixture electrolyte formed by KCl, , Al2O3 in a molar ratio, and the solid-state mixture electrolyte is mixed with a skeleton made of ZrO2 fibers.

[0014] In another aspect, the application provides a processing method of a sensor for in-situ measuring ORP value of high-temperature and high-pressure water, comprising the following steps: S1: preparing a platinum electrode piece and an electrode lead, a plurality of flow guide holes are formed on the platinum electrode piece, and one end of the platinum electrode piece is welded with one end of the electrode lead; S2: preparing an electrode support and an electrode sheath, a through hole is formed in the internal electrode support along the length direction; S3: the other end of the electrode lead is passed through the through hole, the electrode sheath is sleeved outside the part of the electrode lead that passes through the through hole, and an insulating layer is arranged between the inner wall of the electrode sheath and the outer wall of the electrode lead; S4: a sealing assembly is arranged between the inner wall of the through hole and the outer wall of the electrode lead, between the end of the insulating layer close to the electrode support and the electrode lead, and outside the electrode sheath, to obtain a working electrode; S5: preparing a reference electrode, and connecting the reference electrode with the working electrode through a capillary tube to obtain an ORP sensor.

[0015] Further, the S4 comprises: selecting glass paste with a linear expansion coefficient of 9.7*10-6 (1 / ℃) as a sealing sintering material, adding sealing mixed filler prepared by mixing the sealing sintering material and solder to an end surface of the platinum electrode sheet in contact with the electrode support, to obtain a first sealing test piece; placing the first sealing test piece in a heating furnace for heating, while pressurizing the sealing test piece by using a high-pressure gas pump, to obtain a first sealing member; adding sealing mixed filler prepared by mixing Al2O3 adhesive and Al2O3 sand to an end surface of the electrode support in contact with the electrode sheath, to obtain a second sealing test piece; placing the second sealing test piece in a heating furnace for heating, while pressurizing the sealing test piece by using a high-pressure gas pump, to obtain a second sealing member; installing a flange outside the electrode sheath, and jointly extruding a graphite gasket by using the flange and the flow cell, to obtain a third sealing member; and the first sealing member, the second sealing member and the third sealing member jointly constitute the sealing assembly.

[0016] Further, the electrode lead is a platinum wire; the electrode support is made of Al2O3 insulating ceramic or zirconia ceramic; the insulating layer comprises an insulating temperature-resistant coating layer and an externally arranged polytetrafluoroethylene heat-shrinkable tube; the diameter of the flow guide hole is 1-3 mm, the sizes of the plurality of flow guide holes are different, the platinum electrode sheet comprises 2-5 flow guide holes; and the diameter of the through hole is 0.5 mm.

[0017] In still another aspect, the application provides a method for measuring ORP value of high-temperature and high-pressure water in situ, comprising the following steps: placing the working electrode and the reference electrode of the above-mentioned ORP sensor in the same environment to measure the ORP value.

[0018] Compared with the prior art, the application has the following advantages and beneficial effects:

[0019] 1. The application adopts a Pt-Al2O3 single electrode, the Pt-Al2O3 electrode has the characteristics of stable chemical performance, high temperature resistance and corrosion resistance, has a small solubility in a high-temperature and high-pressure aqueous solution system, and almost does not need any maintenance, the sensor is a solid electrode structure, has a firm structure and a long service life; the platinum electrode at the measurement end is designed in a porous sheet structure, can increase the water passing capacity of the electrode during online measurement, realizes sufficient exchange of the measured medium, ensures rapid response and sufficient spatial resolution, and can enhance the anti-pollution capability of the system, when part of the electrode is covered by pollutants, other uncovered parts can also sense normal signals.

[0020] 2. The working electrode measuring end uses alumina insulating ceramic material that can support metal. It has the advantages of high hardness, high temperature resistance, wear resistance, corrosion resistance, electrical insulation, oxidation resistance, good chemical stability, and abundant raw materials. It can effectively prevent metal oxidation and effectively extend the service life of the electrode. In addition, alumina insulating ceramic material has a small coefficient of expansion (close to that of platinum), which can ensure that the geometric dimensions of the conductivity cell remain unchanged and reduce the difficulty of welding and sealing non-metallic materials and platinum materials.

[0021] 3. This invention employs a built-in solid-state reference electrode, placing the ORP working electrode and the reference electrode in the same environment. As the temperature increases, the transport number of most ions approaches 0.5, and in a flowing, high-temperature, high-pressure water environment, it can simultaneously eliminate the liquid junction potential caused by concentration and temperature gradients, thus improving the measurement accuracy of ORP. Furthermore, the sensor and measurement method employed in this scheme effectively enhance the environmental applicability of ORP measurement.

[0022] 4. This invention employs a triple-sealing structure design: the first layer of sealing is the seal between the inner wall of the through-hole and the outer wall of the electrode lead, providing insulation; the second layer of sealing is achieved by using a sealing mixture of Al2O3 adhesive and Al2O3 sand between the end of the insulating layer near the electrode support and the electrode lead, which is compacted, dried, and sealed to form a core seal, thus sealing the electrode sheath from the external environment; the third layer of sealing is achieved by using an external mounting flange and a flow cell to jointly compress a graphite gasket, thus sealing the electrode sheath from the external environment. The sealing between the non-metallic material and the platinum electrode lead is completed through sintering, providing insulation. No special surface treatment is required for the sintered part, and the process does not require a vacuum furnace. The non-metallic material and the platinum electrode are directly sealed through hot-pressing sintering. The sealing point has a fine structure and high reliability, improving the bonding strength between the metallic and non-metallic materials and the sealing performance of the sensor.

[0023] 5. The ORP sensor provided by this invention has a simple structure and can work stably under high temperature of 300℃ and high pressure of 15.5MPa. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the overall structure of a sensor for in-situ measurement of ORP value of high-temperature and high-pressure water provided in Embodiment 1 of the present invention;

[0026] Figure 2 A cross-sectional view of a sensor for in-situ measuring ORP value of high temperature and high pressure water provided for embodiment 1 of the present application.

[0027] Markings in the drawings and corresponding names of parts:

[0028] 1 - platinum electrode sheet, 2 - electrode lead, 3 - electrode support, 4 - electrode sheath, 5 - insulation layer, 11 - flow guide hole, 31 - through hole. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present application clearer and more apparent, the present application will be further described in detail below with reference to the embodiments and drawings, the illustrative embodiments of the present application and the description thereof are only used to explain the present application, and do not limit the present application.

[0030] Embodiment 1

[0031] Due to the limitation of technical problems, at present, all ORP sensors in China are used in low temperature and low pressure environment. The ORP sensor is usually a glass electrode made of quartz glass material. The glass sensing end wall in contact with the test solution is small in thickness, which limits the pressure bearing and temperature resistance of the ORP electrode, and the ORP electrode can only be used in test solution below 75℃. The high temperature and high pressure water environment puts forward higher requirements for the design and manufacture of ORP measuring sensor.

[0032] The main difficulties faced by the development of high temperature and high pressure ORP measuring instrument are as follows: first, the stability of the sensor material under high temperature and high pressure conditions is poor, which reduces the reliability and accuracy of the measurement results; second, the working electrode and the reference electrode are in different temperature and fluid environments. Due to the difference in ion diffusion rate and temperature gradient, liquid junction potential is generated, which affects the measurement results; third, the sealing problem of electrode material. As part of the sensor, it needs to be exposed to high temperature and high pressure solution, while the remaining part must be isolated from the solution. If the sealing structure design is not reasonable or the sealing material is not suitable under high temperature and high pressure conditions, and the sealing performance is not good, the electrode will be corroded and the sealing will be easily failed. Moreover, the electrochemical effect of different materials in high temperature and high pressure solution is highlighted, which causes the damage of the sensor and reduces the service life of the ORP sensor; fourth, due to the increase of solubility or hydrolysis degree of electrode material in high temperature and high pressure water solution, the measured solution is polluted, which leads to unreliable measurement data.

[0033] To address the aforementioned problems in existing technologies, this embodiment provides a sensor capable of in-situ online measurement of ORP values ​​under high-temperature and high-pressure water conditions. This ORP sensor employs a Pt-Al2O3 single electrode. Pt-Al2O3 electrodes are chemically stable, high-temperature resistant, and corrosion-resistant, exhibiting low solubility in high-temperature and high-pressure aqueous solutions. Furthermore, this electrode requires almost no maintenance. Due to its solid-state electrode structure, the sensor is extremely robust and has a long service life. Simultaneously, the platinum electrode at the measuring end is designed with a porous, sheet-like structure, increasing water permeability during online measurement and ensuring sufficient exchange of the measured medium. This guarantees rapid response and sufficient spatial resolution, while also enhancing the system's resistance to contamination. Even when part of the electrode is covered by contaminants, the uncovered portions can still sense a normal signal. An alumina ceramic insulating material that can support the metal is also used at the working electrode measuring end. Alumina ceramics possess advantages such as high hardness, high-temperature resistance, wear resistance, corrosion resistance, electrical insulation, oxidation resistance, good chemical stability, and abundant raw material resources. This effectively prevents metal oxidation and significantly extends the electrode's service life. In this embodiment, the working electrode measuring end of the ORP sensor uses alumina ceramic as the supporting material for the platinum electrode at the measuring end. The material has a small coefficient of expansion (close to that of platinum), which can ensure that the geometric dimensions of the conductivity cell remain unchanged and reduce the difficulty of welding and sealing non-metallic materials and platinum materials.

[0034] Specifically, the structure of the sensor is as follows: Figure 1 and Figure 2 As shown, it includes the following components:

[0035] First, the sensor consists of a working electrode and a reference electrode, which are connected by a capillary tube. The working electrode includes a platinum electrode sheet 1, electrode leads 2, an electrode support 3, and an electrode sheath 4. The reference electrode is a solid-state reference electrode, whose internal electrode uses a solid-state electrolyte mixture formed by KCl, MgCl∙6H2O, and Al2O3 in a molar ratio, with a ZrO2 fiber skeleton mixed in the solid-state electrolyte mixture.

[0036] The platinum electrode sheet 1 has 2 to 5 flow guide holes 11 of different sizes and diameters of 1 to 3 mm, which gives the sensor excellent flushing performance and frequency response characteristics. It achieves sufficient exchange of the measured medium without the need for external power, ensuring rapid potential measurement and sufficient spatial resolution. Furthermore, the porous sheet electrode structure enhances the system's resistance to contamination; when part of the electrode is covered by dirt, the uncovered parts can still sense normal measurement signals.

[0037] One end of electrode lead 2 is welded to one end of platinum electrode sheet 1.

[0038] The inner part of the electrode support 3 is provided with a through hole 31 with a diameter of 0.5 mm in the length direction, and the other end of the electrode lead 2 passes through the through hole 31; the end of the platinum electrode sheet 1 close to the electrode support 3 is fixedly connected with the electrode support 3; the electrode sheath 4 is sleeved on the outer part of the electrode lead 2 passing out of the through hole 31, and one end of the electrode sheath 4 is fixedly connected with the end of the electrode support 3 away from the platinum electrode sheet 1; an insulating layer 5 is arranged between the inner wall of the electrode sheath 4 and the outer wall of the electrode lead 2; a sealing assembly is arranged between the inner wall of the through hole 31 and the outer wall of the electrode lead 2, between the end of the insulating layer 5 close to the electrode support 3 and the electrode lead 2, and on the outer part of the electrode sheath 4.

[0039] In order to ensure the sealing performance of the working electrode sensor of the sensor in a high-temperature and high-pressure environment of 300℃ and 15.5MPa, the sealing assembly of the embodiment includes a first sealing member, a second sealing member and a third sealing member. The first sealing member is filled between the inner wall of the through hole 31 and the outer wall of the electrode lead 2, realizes the sealing between the insulating ceramic and the platinum electrode lead 2, and plays an insulating isolation role; the second sealing member is filled between the end of the insulating layer 5 close to the electrode support 3 and the electrode lead 2, realizes the sealing between the electrode sheath 4 and the external environment; and the third sealing member is arranged on the outer part of the electrode sheath 4, realizes the sealing between the electrode sheath and the external environment.

[0040] In terms of material selection, the electrode lead 2 is a platinum wire; the electrode support 3 adopts Al2O3 insulating ceramic or zirconia ceramic; the insulating layer 5 includes an insulating temperature-resistant coating layer and an externally arranged polytetrafluoroethylene heat shrink tube; the first sealing member adopts a sealing mixed filler composed of a sealing sintered material and solder, and the sealing sintered material selects glass paste; the second sealing member adopts a sealing mixed filler composed of Al2O3 adhesive and Al2O3 sand; the third sealing member is obtained by co-pressing a graphite gasket through a flow cell and a flange installed on the outer part of the electrode sheath 4; and the electrode sheath 4 adopts C276 Hastelloy or 316L stainless steel material.

[0041] Embodiment 2

[0042] The embodiment provides a processing method for preparing the sensor as described in Embodiment 1, including the following steps:

[0043] S1: preparing a platinum electrode sheet and an electrode lead, and the electrode lead is selected from a platinum wire. 2-5 flow guide holes with different sizes and a diameter of 1-3 mm are opened on the platinum electrode sheet, and one end of the platinum electrode sheet is welded with one end of the electrode lead.

[0044] S2: Preparing electrode support and electrode sheath. The electrode support is made of Al2O3 insulating ceramic or zirconia ceramic, and the electrode sheath is made of C276 Hastelloy or 316L stainless steel. A through hole with a diameter of 1-3 mm is formed in the electrode support along the length direction.

[0045] S3: The other end of the electrode lead is passed through the through hole, and the electrode sheath is sleeved outside the part of the electrode lead that passes through the through hole. An insulation layer is arranged between the inner wall of the through hole and the outer wall of the electrode lead, and the insulation layer is an insulating temperature-resistant coating layer and an externally provided polytetrafluoroethylene heat shrink tube.

[0046] S4: A sealing assembly is arranged between the inner wall of the through hole and the outer wall of the electrode lead, between the end of the insulation layer close to the electrode support and the electrode lead, and outside the electrode sheath, to obtain a working electrode. Specifically, it comprises:

[0047] S4.1: Glass paste with a linear expansion coefficient of 9.7×10-6 (1 / ℃) is selected as the sealing sintering material. The linear expansion coefficient of the glass paste is close to that of Al2O3, and it is fused with the metal material under high temperature and pressure. The sealing mixed filler prepared by mixing the sealing sintering material and solder is added to the end face of the platinum electrode sheet in contact with the electrode support, to obtain a first sealing test piece. The first sealing test piece is heated in a heating furnace, and at the same time, a high-pressure gas pump is used to pressurize the sealing test piece. The thermal flow of the solder is used to compensate for the micro concave-convex surface of the sealing material, to increase the actual contact area and strengthen the diffusion process. A first sealing member is obtained.

[0048] S4.2: The sealing mixed filler prepared by mixing Al2O3 adhesive and Al2O3 sand is added to the end face of the electrode support in contact with the electrode sheath, to obtain a second sealing test piece. The second sealing test piece is heated in a heating furnace, and at the same time, a high-pressure gas pump is used to pressurize the sealing test piece. A second sealing member is obtained.

[0049] The process does not require special surface treatment of the sintered part, and does not need to be performed in a vacuum furnace. The sealing of the non-metallic material and the platinum electrode is realized directly by the method of hot-pressing sintering. The sealing point has a fine and reliable organization, and the bonding strength of the metal material and the non-metallic material and the sealing performance of the sensor are improved.

[0050] S4.3: A flange is installed outside the electrode sheath, and the flange and the flow cell are used to squeeze a graphite gasket together, to obtain a third sealing member. The first sealing member, the second sealing member, and the third sealing member jointly constitute the sealing assembly.

[0051] S5: preparing a reference electrode, connecting the reference electrode and the working electrode through a capillary to obtain the sensor as described in Example 1.

[0052] The sensor processed by the method has a six-electrode structure, and a built-in double temperature measuring electrode, so that the "current" electrode and the "voltage" electrode are separated, the stray current is eliminated, and the influence of polarization impedance is avoided. The electrode is not disturbed by the outside of the conductive cell, and the requirements of high sensitivity, long-term, fast and high-precision measurement of the conductivity sensor can be met. The three-way conductive cell structure with a large aperture and a short length makes the six-electrode conductivity sensor have good water flushing performance and frequency response characteristics, and no external power is needed, so that sufficient exchange of the measured medium can be realized, and fast conductivity measurement and sufficient spatial resolution can be ensured. In addition, the whole turning process is used to form six electrode circular groove rings at one time, and six platinum film electrodes are directly made, which ensures the symmetry of the six electrodes and improves the interchangeability of the conductive cell, and the accuracy and stability are ideal. Moreover, the sensor adopts a four-seal structure, which is reliable in sealing and ensures the service reliability of the high-temperature and high-pressure conductivity sensor in a high-temperature and high-pressure water environment.

[0053] The high-temperature and high-pressure conductivity sensor processed by the processing method provided in the embodiment can work continuously for more than 1000 hours under the condition of 300℃ and 15.5MPa high-temperature and high-pressure working conditions.

[0054] Example 3

[0055] The embodiment provides a method for measuring ORP value by using the sensor provided in Example 1.

[0056] At present, the specific measurement method of ORP value is to insert the working electrode and the reference electrode into the solution to be measured, so that electron transfer occurs between the solution and the surface of the electrode, and a potential difference is generated between the two electrodes, which is the ORP value. According to the Nernst equation, the relationship between ORP and other factors can be obtained, as shown in formula (1):

[0057] (1)

[0058] In the formula, Ew is the actual ORP (mV); E0 is the standard electrode potential of the redox electron pair (mV); R is the gas constant (8.314 J / K·mol); T is the absolute temperature (K); n is the electrochemical equivalent number (mol-1); F is the Faraday constant (96500 C / mol); [Oxid] is the molar concentration of the oxidant (M); and [Red] is the molar concentration of the reducing agent (M).

[0059] From the above formula, in the specific ORP value measurement process, the ion concentration and temperature and other factors in the solution will affect the ORP value. Currently, an external reference electrode is commonly used for measurement. This method usually places the reference electrode in a room temperature environment (cold end), and the working electrode is in a high temperature and high pressure environment (hot end). A capillary is used to connect the cold and hot ends to maintain pressure balance. Because the reference electrode and the working electrode are in different temperature and fluid environments, the different ion diffusion rates and temperature gradients will produce a liquid junction potential, which will affect the measurement results. At room temperature, a saturated KCl solution with similar ion diffusion rates is usually used to eliminate the liquid junction potential.

[0060] To effectively eliminate the measurement error caused by the liquid junction potential formed during the ORP value measurement process in the high temperature and high pressure water environment, the solid-state reference electrode is used in this embodiment. The working electrode and the reference electrode of the sensor provided in Embodiment 1 are in the same environment (high temperature and high pressure water environment) for measurement. As the temperature rises, the number of most ion migrations approaches 0.5. In the high temperature and high pressure water environment, the liquid junction potential caused by the concentration gradient and the temperature gradient can be eliminated at the same time, and the measurement accuracy of the ORP value is improved.

[0061] This method can effectively improve the environmental applicability of ORP value measurement.

[0062] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A sensor for in-situ measurement of ORP values ​​in high-temperature and high-pressure water, characterized in that, The device includes a working electrode and a reference electrode, which are connected by a capillary tube. The working electrode includes a platinum electrode sheet (1), an electrode lead (2), an electrode support (3), and an electrode sheath (4). The platinum electrode sheet (1) is provided with multiple flow guide holes (11), and one end of the electrode lead (2) is welded to one end of the platinum electrode sheet (1). The electrode support (3) has through holes (31) along its length, and the other end of the electrode lead (2) passes through the through holes (31). The end of the platinum electrode sheet (1) closest to the electrode support (3) is connected to the electrode support. The electrode sleeve (4) is fixedly connected to the electrode support (3) at the outside of the portion of the electrode lead (2) that passes through the through hole (31). One end of the electrode sleeve (4) is fixedly connected to the end of the electrode support (3) away from the platinum electrode sheet (1). An insulating layer (5) is provided between the inner wall of the electrode sleeve (4) and the outer wall of the electrode lead (2). A sealing assembly is provided between the inner wall of the through hole (31) and the outer wall of the electrode lead (2), between the end of the insulating layer (5) near the electrode support (3) and the electrode lead (2), and on the outside of the electrode sleeve (4). The working electrode is a porous sheet-like Pt-Al2O3 type single electrode, the electrode support (3) is made of Al2O3 insulating ceramic or zirconium oxide ceramic, and the sealing assembly is used to seal the sensor by sintering and pressurizing.

2. The sensor for in-situ measurement of ORP value of high-temperature and high-pressure water according to claim 1, characterized in that, The sealing assembly includes a first seal, a second seal, and a third seal; the first seal is filled between the inner wall of the through hole (31) and the outer wall of the electrode lead (2); the second seal is filled between the end of the insulating layer (5) near the electrode support (3) and the electrode lead (2); and the third seal is disposed on the outside of the electrode sheath (4).

3. A sensor for in-situ measurement of ORP value of high-temperature and high-pressure water according to claim 2, characterized in that, The electrode lead (2) is a platinum wire; the insulation layer (5) includes an insulating and heat-resistant coating layer and an external polytetrafluoroethylene heat shrink tubing; the first sealing element is a sealing mixed filler composed of sealing sintering material and solder, and the sealing sintering material is glass slurry; the second sealing element is a sealing mixed filler composed of Al2O3 adhesive and Al2O3 sand; the third sealing element is obtained by extruding a graphite gasket together with a flow cell and a flange installed outside the electrode sheath (4); the electrode sheath (4) is made of C276 Hastelloy or 316L stainless steel.

4. A sensor for in-situ measurement of ORP value of high-temperature and high-pressure water according to claim 1, characterized in that, The diameter of the flow guide hole (11) is 1~3mm, and the multiple flow guide holes (11) are of different sizes. The platinum electrode sheet (1) includes 2~5 flow guide holes (11); the diameter of the through hole (31) is 0.5mm.

5. A sensor for in-situ measurement of ORP values ​​in high-temperature and high-pressure water according to claim 1, characterized in that, The reference electrode is a solid-state reference electrode.

6. A sensor for in-situ measurement of ORP values ​​in high-temperature and high-pressure water according to claim 5, characterized in that, The internal electrode of the reference electrode is a solid mixture electrolyte formed by KCl, MgCl∙6H2O and Al2O3 in a molar ratio, and the solid mixture electrolyte contains a framework made of ZrO2 fibers.

7. A method for fabricating a sensor for in-situ measurement of ORP values ​​in high-temperature and high-pressure water, characterized in that, Includes the following steps: S1: Prepare a platinum electrode sheet and an electrode lead wire, open multiple flow guide holes on the platinum electrode sheet, and weld one end of the platinum electrode sheet to one end of the electrode lead wire; S2: Prepare an electrode support and an electrode sheath, and open a through hole along the length direction inside the electrode support; S3: Pass the other end of the electrode lead through the through hole, and put the electrode sheath on the outside of the part of the electrode lead that passes through the through hole. An insulating layer is provided between the inner wall of the electrode sheath and the outer wall of the electrode lead. S4: A sealing assembly is provided between the inner wall of the through hole and the outer wall of the electrode lead, between the end of the insulating layer near the electrode support and the electrode lead, and outside the electrode sheath to obtain a working electrode; S5: Prepare a reference electrode, and connect the reference electrode to the working electrode through a capillary tube to obtain an ORP sensor. The working electrode is a porous sheet-like Pt-Al2O3 type single electrode, the electrode support is made of Al2O3 insulating ceramic or zirconium oxide ceramic, and the sealing assembly is used to seal the sensor by sintering and pressurizing.

8. The method for fabricating a sensor for in-situ measurement of ORP values ​​in high-temperature and high-pressure water according to claim 7, characterized in that, S4 includes: A glass slurry with a linear expansion coefficient of 9.7×10-6 (1 / ℃) was selected as the sealing sintering material. The sealing sintering material was mixed with solder to obtain a sealing mixed filler, which was added to the end face of the platinum electrode sheet in contact with the electrode support to obtain the first sealing specimen. The first sealing specimen was placed in a heating furnace for heating, and at the same time, a high-pressure air pump was used to pressurize the sealing specimen to obtain the first sealing element. A sealing filler prepared by mixing Al2O3 adhesive and Al2O3 sand is added to the end face of the electrode support that contacts the electrode sheath to obtain a second sealing specimen; the second sealing specimen is placed in a heating furnace for heating, and at the same time, a high-pressure air pump is used to pressurize the sealing specimen to obtain a second seal; A flange is installed on the outside of the electrode sheath, and the graphite gasket is pressed together by the flange and the flow cell to obtain a third seal; the first seal, the second seal, and the third seal together constitute the sealing assembly.

9. A method for fabricating a sensor for in-situ measurement of ORP values ​​in high-temperature and high-pressure water according to claim 7 or 8, characterized in that, The electrode lead is a platinum wire; the electrode support is made of Al2O3 insulating ceramic or zirconium oxide ceramic; the insulating layer includes an insulating and heat-resistant coating layer and an external polytetrafluoroethylene heat shrink tubing; the diameter of the flow guide hole is 1~3mm, and the sizes of the multiple flow guide holes are different; the platinum electrode sheet includes 2~5 flow guide holes; the diameter of the through hole is 0.5mm.

10. A method for in-situ measurement of ORP value in high-temperature and high-pressure water, characterized in that, The method includes the following steps: placing the working electrode and the reference electrode of the sensor for measuring the ORP value of high-temperature and high-pressure water in situ according to any one of claims 1-6 in the same environment to measure the ORP value.

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