CN116256403A - Method for in-situ high-temperature high-pressure water ORP value, sensor and processing method thereof - Google Patents

Method for in-situ high-temperature high-pressure water ORP value, sensor and processing method thereof Download PDF

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CN116256403A
CN116256403A CN202211489257.9A CN202211489257A CN116256403A CN 116256403 A CN116256403 A CN 116256403A CN 202211489257 A CN202211489257 A CN 202211489257A CN 116256403 A CN116256403 A CN 116256403A
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electrode
sealing
sheath
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张军平
王家贞
闫晓
姜峨
褚力
王宏庆
徐建军
赵永福
夏小娇
傅晟伟
聂涛涛
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Nuclear Power Institute of China
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Abstract

The invention belongs to the field of electrochemical sensors, and discloses a method for in-situ high-temperature and high-pressure water ORP value, a sensor and a processing method thereof, wherein the sensor consists of an electrode core body, an electrode supporting component, a sealing component, a reference electrode and the like, and specifically comprises the following steps: the electrode has the characteristics of stable chemical performance, high temperature resistance and corrosion resistance, has small solubility in a high-temperature high-pressure aqueous solution system, almost does not need any maintenance, and has firm structure and long service life because the sensor is of a solid electrode structure.

Description

Method for in-situ high-temperature high-pressure water ORP value, sensor and processing method thereof
Technical Field
The invention relates to the field of electrochemical sensors, in particular to a method for in-situ high-temperature and high-pressure water ORP value, a sensor and a processing method thereof.
Background
The oxidation-reduction potential (ORP) is one of the important indicators of a water chemistry system and reflects the macroscopic oxidation-reduction properties exhibited by all materials in the system. The measurement of oxidation-reduction potential has been widely used in the fields of nuclear power plants, thermal power plants, hydrometallurgy, geochemistry, water treatment, soil environment monitoring, metal corrosion, resource exploration and the like. ORP can be used as a standard for evaluating the quality of water, and qualitatively evaluate the quality of reactor coolant water and the corrosion rate of system structural materials. The oxidation-reduction potential can be measured by using an ORP oxidation-reduction electrode and is obtained by converting the potential between the measuring electrode and the reference electrode. Although the redox potential measurement is widely applied in low-temperature and low-pressure environments, the redox potential is relatively rarely applied in high-temperature and high-pressure environments due to the limitation of the preparation technology of the high-temperature and high-pressure resistant working electrode and the reference electrode and the lack of thermodynamic data in a high-temperature and high-pressure hydrothermal system.
ORP sensors have been widely used in nuclear power plants for many years to control the amount of hydrogen produced to reduce intergranular stress corrosion cracking of furnace water and high pressure feedwater reactors. The coolant of the nuclear reactor is high-temperature high-pressure water, the physical and chemical properties of the high-temperature high-pressure water are greatly changed compared with those of the water at normal temperature, particularly, the density, dielectric constant and other properties of the water are obviously different from those of the water at normal temperature under supercritical conditions, if the traditional online sampling, cooling and chemical instrument monitoring processes are adopted, when a water sample reaches a monitoring instrument, the water quality of the water sample can be changed, and the actual condition of the water quality cannot be reflected in time. If the ORP sensor can be used in high-temperature and high-pressure water, the ORP value of the high-temperature and high-pressure solution can be monitored in real time in situ by the high-temperature and high-pressure ORP tester, the water quality change caused by any instant change in the coolant can be captured, and the oxidation-reduction condition of the system can be reflected and controlled more timely, so that the corrosion degree of a loop is reduced, the migration of corrosion products is reduced, and the method has important significance for knowing the corrosion behavior of the material in the high-temperature and high-pressure water.
Because of the limitation of technical problems, the current use environment of each ORP sensor in China is under low temperature and low pressure conditions, the glass electrode is usually made of quartz glass material, the wall thickness of the glass sensing end contacted with the test solution is smaller, so that the ORP electrode has limited pressure bearing and temperature resisting capabilities and can only be used in the test solution below 75 ℃.
In view of this, the present application is specifically proposed.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: the existing ORP measurement technology is not suitable for online real-time monitoring of ORP values of high-temperature and high-pressure solutions. The purpose is to provide a method for in-situ high-temperature high-pressure water ORP value, a sensor and a processing method thereof, wherein a porous sheet-shaped Pt-Al2O3 single electrode with stable chemical property, high temperature resistance and corrosion resistance and smaller solubility in a high-temperature high-pressure water solution system is selected, a support piece with small material deformation coefficient, low thermal expansion coefficient, chemical corrosion resistance, high temperature resistance and excellent performance is used, and meanwhile, the sensor is subjected to sealing treatment in a sintering pressurization mode, so that the ORP sensor can stably work at 300 ℃ and 15.5MPa high pressure.
The invention is realized by the following technical scheme:
in one aspect, the invention provides a sensor for ORP value of in-situ high-temperature high-pressure water, which comprises a working electrode and a reference electrode, wherein the working electrode is connected with the reference electrode through a capillary tube; the working electrode comprises a platinum electrode plate, an electrode lead, an electrode support piece and an electrode sheath; the platinum electrode plate is provided with a plurality of diversion holes, and one end of the electrode lead is welded with one end of the platinum electrode plate; a through hole is formed in the electrode support along the length direction, and the other end of the electrode lead penetrates through the through hole; one end of the platinum electrode plate, which is close to the electrode support, is fixedly connected with the electrode support; the electrode sheath is sleeved outside the part of the electrode lead, which penetrates through the through hole, and one end of the electrode sheath is fixedly connected with one end of the electrode support piece, which is far 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; and sealing assemblies are arranged between the inner wall of the through hole and the outer wall of the electrode lead, between the end part, close to the electrode support, of the insulating layer and the electrode lead and outside the electrode sheath.
Further, the seal assembly includes a first seal, a second seal, and a third seal; 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 an end of the insulating layer, which is close to the electrode support, and the electrode lead; the third seal is disposed outside the electrode sheath.
Further, the electrode lead is a platinum wire; the electrode support member adopts Al 2 O 3 Insulating ceramic or zirconia ceramic; the insulation layer comprises an insulation temperature-resistant coating layer and an external polytetrafluoroethylene heat shrinking pipe; the first sealing piece adopts a sealing mixed filler composed of a sealing sintering material and solder, and the sealing sintering material adopts glass slurry; the second sealing piece adopts Al 2 O 3 Adhesive and Al 2 O 3 Sealing mixed filler composed of sand; the third sealing piece is obtained by co-extruding a graphite gasket with a flange arranged outside the electrode sheath through a flow cell; the electrode sheath is made of C276 hastelloy or 316L stainless steel.
Further, the diameter of the diversion holes is 1-3 mm, the sizes of a plurality of diversion holes are different, and the platinum electrode plate comprises 2-5 diversion holes; the diameter of the through hole is 0.5mm.
Further, the reference electrode is a solid state reference electrode.
Further, the internal electrode of the reference electrode is composed of KCl and MgCl.6H 2 O、Al 2 O 3 A solid mixture electrolyte formed by mole ratio, the solid mixture electrolyte being mixed with ZrO 2 A skeleton made of fiber.
On the other hand, the invention provides a processing method of an in-situ high-temperature high-pressure water ORP value sensor, which comprises the following steps: s1: preparing a platinum sheet electrode and an electrode lead, forming a plurality of diversion holes on the platinum sheet electrode, and welding one end of the platinum sheet electrode with one end of the electrode lead; s2: preparing an electrode support and an electrode sheath, wherein a through hole is formed in the electrode support along the length direction; s3: the other end of the electrode lead passes through the through hole, the electrode sheath is sleeved outside the part of the electrode lead, which 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 part of the insulating layer, which is close to the electrode support piece, and the electrode lead, and outside the electrode sheath, so as 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 the ORP sensor.
Further, the step S4 includes: selecting glass slurry with a linear expansion coefficient of 9.7x10 < -6 > (1/℃ C.) as a sealing sintering material, and adding a sealing mixed filler prepared by mixing the sealing sintering material and solder to the end surface of the platinum sheet electrode, which is in contact with the electrode support, so as to obtain a first sealing test piece; heating the first sealing test piece in a heating furnace, and pressurizing the sealing test piece by using a high-pressure air pump to obtain a first sealing piece; al is added with 2 O 3 Adhesive and Al 2 O 3 Adding a sealing mixed filler prepared by sand mixing to the end surface of the electrode support piece, which is in contact with the motor sheath, so as to obtain a second sealingA test piece; heating the second sealing test piece in a heating furnace, and pressurizing the sealing test piece by using a high-pressure air pump to obtain a second sealing piece; installing a flange outside the motor sheath, and co-extruding a graphite gasket by using the flange and the flow cell to obtain a third sealing element; the first seal, the second seal, and the third seal together comprise the seal assembly.
Further, the electrode lead is a platinum wire; the electrode support member adopts Al 2 O 3 Insulating ceramic or zirconia ceramic; the insulation layer comprises an insulation temperature-resistant coating layer and an external polytetrafluoroethylene heat shrinking pipe; the diameter of the diversion holes is 1-3 mm, the sizes of a plurality of diversion holes are different, and the platinum electrode plate comprises 2-5 diversion holes; the diameter of the through hole is 0.5mm.
In yet another aspect, the invention provides a method of in situ heat and pressure water ORP values, comprising the steps of: the working electrode and the reference electrode of the ORP sensor are placed in the same environment to measure the ORP value.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. the invention adopts Pt-Al 2 O 3 Single electrode, pt-Al 2 O 3 The electrode has the characteristics of stable chemical property, high temperature resistance and corrosion resistance, has smaller solubility in a high-temperature high-pressure aqueous solution system, and almost does not need any maintenance, and the sensor has a solid electrode structure, so that the sensor has a firm structure and long service life. The platinum electrode of the measuring end is designed into a porous sheet structure, so that the water passing capability of the electrode during online measurement can be increased, the full exchange of the measured medium can be realized, the quick response and the enough spatial resolution can be ensured, the anti-pollution capability of the system can be enhanced, and when part of the electrode is covered by dirt, other uncovered parts can sense normal signals.
2. The working electrode measuring end uses alumina insulating ceramic material capable of supporting metal, has the advantages of high hardness, high temperature resistance, wear resistance, corrosion resistance, electric insulation, oxidation resistance, good chemical stability, rich raw material accumulation and the like, can effectively prevent the metal from being oxidized, can effectively prolong the service life of the electrode, has small expansion coefficient (basically similar to platinum), can ensure that the geometric dimension of a conductive tank is kept unchanged, and can reduce the welding sealing difficulty of nonmetallic materials and platinum materials.
3. The invention adopts the built-in solid reference electrode, the ORP working electrode and the reference electrode are in the same environment, the migration number of most ions is close to 0.5 along with the temperature rise, and the liquid connection potential caused by concentration gradient and temperature gradient can be eliminated simultaneously in the high-temperature and high-pressure water environment with fluidity, so that the measurement accuracy of ORP is improved. In addition, by adopting the sensor and the measuring method, the environmental applicability of ORP measurement can be effectively improved.
4. The invention adopts a triple sealing structure design: the first resealing is the sealing between the inner wall of the through hole and the outer wall of the electrode lead and plays an insulating and isolating role; the second resealing is to use Al between the end of the insulating layer near the electrode support and the electrode lead 2 O 3 Adhesive and Al 2 O 3 The sealing mixed filler composed of sand is compacted, dried and sealed to form a core sealing piece, so that the sealing between the electrode sheath and the external environment is realized; and the third seal is realized by arranging a mounting flange outside the electrode sheath and extruding a graphite gasket together with the flow cell. The sealing between the nonmetallic material and the platinum electrode lead is completed through sintering, the insulating and isolating effects are achieved, special surface treatment is not needed for the sintered part, the sealing between the nonmetallic material and the platinum electrode is directly achieved through a hot-pressing sintering method, the sealing point structure is fine, the reliability is high, and the bonding strength of the metallic material and the nonmetallic material and the sealing performance of the sensor are improved.
5. The ORP sensor provided by the invention has a simple structure and can stably work at a high temperature of 300 ℃ and a high pressure of 15.5 MPa.
Drawings
In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings that are needed in the examples will be briefly described below, it being understood that the following drawings only illustrate some examples of the present invention and therefore should not be considered as limiting the scope, and that other related drawings may be obtained from these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of the overall structure of an in-situ high temperature and high pressure water ORP sensor according to embodiment 1 of the present invention;
FIG. 2 is a cross-sectional view of an in-situ high temperature and high pressure water ORP sensor according to example 1 of the present invention.
In the drawings, the reference numerals and corresponding part names:
the electrode comprises a 1-platinum electrode plate, a 2-electrode lead, a 3-electrode support piece, a 4-electrode sheath, a 5-insulating layer, 11-diversion holes and 31-through holes.
Detailed Description
For the purpose of making apparent the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the following examples and the accompanying drawings, wherein the exemplary embodiments of the present invention and the descriptions thereof are for illustrating the present invention only and are not to be construed as limiting the present invention.
Example 1
Because of the limitation of technical problems, each ORP sensor in China is used in a low-temperature and low-pressure environment at present. ORP sensors are typically glass electrodes made of quartz glass material, with small wall thicknesses at the glass sensing end in contact with the test solution, resulting in limited pressure and temperature resistance of the ORP electrode, and can only be used in test solutions below 75 ℃. The high temperature and high pressure water environment puts higher demands on the design and manufacture of ORP sensors.
The main difficulties faced by the development of high temperature and high pressure ORP meters are presented in the following ways: firstly, the sensor material has poor stability under high temperature and high pressure conditions, and the reliability and accuracy of the measurement result are reduced; secondly, the working electrode and the reference electrode are in different temperatures and fluid environments, and liquid connection potential can be generated due to the difference of ion diffusion rate and temperature gradient, so that the measurement result is influenced; thirdly, the sealing problem of the electrode material is that the part serving as the sensor needs to be exposed to high-temperature and high-pressure solution, the rest part needs to be isolated from the solution, if the sealing structure of the sensor is unreasonable under the high-temperature and high-pressure condition or the sealing material is not properly selected, the electrode is corroded and the sealing failure is easily caused due to poor sealing performance, and the electrochemical effect among different materials in the high-temperature and high-pressure solution is highlighted, so that the service life of the ORP sensor is reduced due to the damage of the sensor; fourth, the electrode material in the high temperature and high pressure aqueous solution is increased in solubility or hydrolysis degree to pollute the solution to be measured, resulting in unreliable measurement data.
Aiming at the problems in the prior art, the embodiment provides a sensor capable of measuring ORP value in situ on line under the conditions of high-temperature and high-pressure water environment. The ORP sensor adopts Pt-Al 2 O 3 Single electrode, pt-Al 2 O 3 The electrode has the characteristics of stable chemical performance, high temperature resistance and corrosion resistance, has smaller solubility in a high-temperature high-pressure aqueous solution system, and almost does not need any maintenance, and because the sensor is of a solid electrode structure, the structure is very firm and the service life is long. Meanwhile, the platinum electrode at the measuring end is designed into a porous sheet structure, so that the water passing capacity of the electrode during online measurement is increased, the full exchange of the measured medium is realized, the quick response and the enough spatial resolution are ensured, the anti-pollution capacity of the system can be enhanced, and when part of the electrode is covered by dirt, other uncovered parts can sense normal signals. Alumina ceramic insulating material capable of supporting metal is also used at the measuring end of the working electrode. The alumina ceramic has the advantages of high hardness, high temperature resistance, wear resistance, corrosion resistance, electric insulation, oxidation resistance, good chemical stability, rich raw material accumulation and the like, can effectively prevent oxidation of metal, and can effectively prolong the service life of the electrode. In the embodiment, the working electrode measuring end of the ORP sensor adopts alumina ceramic as a supporting material of a platinum electrode of the measuring end, and the material has small expansion coefficient (basically similar to platinum), can ensure that the geometric dimension of a conductivity cell is kept unchanged, and can reduce the welding sealing difficulty of a nonmetallic material and a platinum material.
Specifically, the structure of the sensor is shown in fig. 1 and 2, and the sensor comprises the following components:
first, the sensor is composed of a working electrode and a reference electrode, and the working electrode and the reference electrode are connected through a capillary tube. The working electrode comprises a platinum electrode plate 1, an electrode lead 2, an electrode support 3 and an electrode sheath 4; the reference electrode is solid reference electrode, and its internal electrode adopts the material formed from KCl and MgCl.6H 2 O、Al 2 O 3 A solid mixture electrolyte formed by mole ratio, the solid mixture electrolyte being mixed with ZrO 2 A skeleton made of fiber.
The platinum electrode plate 1 is provided with 2-5 diversion holes 11 with different sizes and diameters of 1-3 mm, so that the sensor has good flushing performance and frequency response characteristics, no external power is needed, the full exchange of the measured medium can be realized, and the rapid potential measurement and sufficient spatial resolution can be ensured. In addition, the porous sheet electrode structure can enhance the anti-pollution capability of the system, and when part of the electrode is covered by dirt, other uncovered parts can sense normal measurement signals.
One end of the electrode lead 2 is welded to one end of the platinum electrode tab 1.
The inside of the electrode support 3 is provided with a through hole 31 having a diameter of 0.5mm in the length direction, and the other end of the electrode lead 2 passes through the through hole 31; one end of the platinum electrode plate 1, which is close to the electrode support 3, is fixedly connected with the electrode support 3; the electrode sheath 4 is sleeved outside the part of the electrode lead 2 penetrating out of the through hole 31, and one end of the electrode sheath 4 is fixedly connected with one end of the electrode support 3, which is far away from the platinum electrode plate 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; sealing assemblies are 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 outside the electrode sheath 4.
In order to ensure the sealing performance of the working electrode sensor of the sensor in a high-temperature and high-pressure environment at 300 ℃ and 15.5MPa, the sealing assembly of the embodiment comprises a first sealing element, a second sealing element and a third sealing element. Wherein, the first sealing element is filled between the inner wall of the through hole 31 and the outer wall of the electrode lead 2, so as to realize the sealing between the insulating ceramic and the platinum electrode lead 2 and play a role of insulating isolation; a second sealing member is filled between the end part, close to the electrode support 3, of the insulating layer 5 and the electrode lead 2, so that the electrode sheath 4 is sealed with the external environment; the third sealing element is arranged outside the electrode sheath 4 to realize the sealing between the electrode sheath and the external environment.
In terms of material selection, the electrode lead 2 is a platinum wire; the electrode support 3 is made of Al 2 O 3 Insulating ceramic or zirconia ceramic; the insulation layer 5 comprises an insulation temperature-resistant coating layer and an external polytetrafluoroethylene heat shrinking pipe; the first sealing piece adopts a sealing mixed filler composed of a sealing sintering material and solder, and the sealing sintering material adopts glass slurry; the second sealing piece adopts Al 2 O 3 Adhesive and Al 2 O 3 Sealing mixed filler composed of sand; the third sealing element is obtained by co-extruding a graphite gasket with a flange arranged outside the electrode sheath 4 through a flow cell; the electrode sheath 4 is made of C276 hastelloy or 316L stainless steel.
Example 2
This example provides a process for preparing a sensor as described in example 1, comprising the steps of:
s1: platinum sheet electrodes and electrode leads are prepared, and the electrode leads are platinum wires. And 2-5 deflector holes with different sizes and diameters of 1-3 mm are formed in the platinum sheet electrode, and one end of the platinum sheet electrode is welded with one end of the electrode lead.
S2: an electrode support and an electrode sheath are prepared. The electrode support member adopts Al 2 O 3 The insulating ceramic or zirconia ceramic, and the electrode sheath is made of C276 hastelloy or 316L stainless steel. And a through hole with the diameter of 1-3 mm is formed in the electrode support piece along the length direction.
S3: and the other end of the electrode lead passes through the through hole, the electrode sheath is sleeved outside the part of the electrode lead, which passes through the through hole, an insulating layer is arranged between the inner wall of the electrode sheath and the outer wall of the electrode lead, and the insulating layer is an insulating heat-resistant coating layer and a polytetrafluoroethylene heat shrink tube which is arranged outside.
S4: and a sealing component is arranged between the inner wall of the through hole and the outer wall of the electrode lead, between the end part, close to the electrode support piece, of the insulating layer and the electrode lead and outside the electrode sheath, so that a working electrode is obtained. The method specifically comprises the following steps:
s4.1: glass slurry with the linear expansion coefficient of 9.7x10 < -6 > (1/DEGC) is selected as a sealing sintering material, the linear expansion coefficients of the glass slurry and Al2O3 are close, and the glass slurry and the metal material are fused together under high-temperature pressurization. Adding a sealing mixed filler prepared by mixing the sealing sintering material and the welding flux to the end surface of the platinum sheet electrode, which is in contact with the electrode support piece, so as to obtain a first sealing test piece; and (3) placing the first sealing test piece in a heating furnace for heating, pressurizing the sealing test piece by using a high-pressure air pump, and compensating microscopic concave-convex on the surface of the sealing material by using the thermal flow of the solder so as to increase the substantial contact area and strengthen the diffusion process. A first seal is obtained.
S4.2: al is added with 2 O 3 Adhesive and Al 2 O 3 Adding the sealing mixed filler prepared by sand mixing to the end surface of the electrode support piece, which is in contact with the motor sheath, so as to obtain a second sealing test piece; heating the second sealing test piece in a heating furnace, and pressurizing the sealing test piece by using a high-pressure air pump to obtain a second sealing piece;
the process does not need special surface treatment on the sintered part, does not need to be carried out in a vacuum furnace, directly realizes the sealing of the nonmetallic material and the platinum electrode by a hot-press sintering method, has fine and compact structure of sealing points and high reliability, and improves the bonding strength of the metallic material and the nonmetallic material and the sealing performance of the sensor.
S4.3: installing a flange outside the motor sheath, and co-extruding a graphite gasket by using the flange and the flow cell to obtain a third sealing element; the first seal, the second seal, and the third seal together comprise the seal assembly.
S5: a reference electrode was prepared and connected to the working electrode by capillary tube to obtain a sensor as described in example 1.
The sensor processed by the method adopts a six-electrode structure, is internally provided with double temperature measuring electrodes, realizes the separation of a current electrode and a voltage electrode, eliminates stray current and avoids the influence of polarization impedance. The electrode is not interfered by the outside of the conductivity cell, and the requirements of high sensitivity, long-term, quick and high-precision measurement of the conductivity sensor can be met. The three-way conductivity cell structure design with large aperture and short length ensures that the six-electrode conductivity sensor has good flushing performance and frequency response characteristic, does not need external power, can realize the full exchange of the measured medium, and can ensure the rapid conductivity measurement and sufficient spatial resolution. In addition, in the aspect of processing the conductivity cell, six electrode annular grooves are formed at one time by adopting an integral turning process, and six platinized membrane electrodes are directly manufactured, so that the symmetry of the six electrodes is ensured, the interchangeability of the conductivity cell is improved, and the accuracy and the stability are ideal. And the sensor adopts a quadruple sealing structure, the sealing is reliable, and the service reliability of the high-temperature high-pressure conductivity sensor under high-temperature high-pressure water environment is ensured.
The high-temperature high-pressure conductivity sensor manufactured by the processing method provided by the embodiment can continuously work for more than 1000 hours under the working condition of high temperature and high pressure of 300 ℃ and 15.5 MPa.
Example 3
This embodiment provides a method of ORP value measurement using the sensor as provided in embodiment 1.
At present, the specific measurement method of the ORP value is to insert a working electrode and a reference electrode into a solution to be measured, electron transfer occurs on the surfaces of the solution and the electrode, and potential difference is generated between the two electrodes, namely the ORP value. The ORP can be related to other factors according to the Nernst equation, as shown in equation (1):
Figure BDA0003964203290000081
wherein Ew is the actual ORP (mV); e0 is the standard electrode potential (mV) of the redox electron pair; r is a gas constant (8.314J/K.mol); t is absolute temperature (K); n is the number of electrochemical equivalents (mol-1); f is Faraday constant (96500C/mol); [ Oxid ] is the molar concentration (M) of the oxidizing agent; [ Red ] is the molar concentration (M) of the reducing agent.
As can be seen from the above equation, in a specific ORP value measurement process, factors such as ion concentration and temperature in the solution can have an influence on the ORP value. The reference electrode is usually placed in a room temperature environment (cold end), the working electrode is placed in a high-temperature and high-pressure environment (hot end), the cold end and the hot end are connected by a capillary tube to keep pressure balance, the difference of ion diffusion rate and temperature gradient can generate liquid connection potential to influence the measurement result because the reference electrode and the working electrode are placed in different temperatures and fluid environments, and saturated KCl solution with similar ion diffusion rate is usually needed to eliminate the liquid connection potential at room temperature.
In order to effectively eliminate measurement errors caused by liquid connection potential formed in the process of summarizing ORP value measurement of high-temperature and high-pressure water environment, in the embodiment, a built-in solid reference electrode is adopted, the working electrode and the reference electrode of the sensor provided in the embodiment 1 are measured in the same environment (high-temperature and high-pressure water environment), along with the increase of temperature, the migration number of most ions is close to 0.5, and the liquid connection potential caused by concentration gradient and temperature gradient can be simultaneously eliminated in the high-temperature and high-pressure water environment with fluidity, so that the measurement accuracy of the ORP value is improved.
The method can effectively improve the environmental applicability of ORP value measurement.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims (10)

1. The in-situ high-temperature high-pressure water ORP value sensor is characterized by comprising a working electrode and a reference electrode, wherein the working electrode is connected with the reference electrode through a capillary tube; the working electrode comprises a platinum electrode plate (1), an electrode lead (2), an electrode support (3) and an electrode sheath (4); the platinum electrode plate (1) is provided with a plurality of diversion holes (11), and one end of the electrode lead (2) is welded with one end of the platinum electrode plate (1); the inside of the electrode support (3) is provided with a through hole (31) along the length direction, and the other end of the electrode lead (2) passes through the through hole (31); one end, close to the electrode support (3), of the platinum electrode sheet (1) is fixedly connected with the electrode support (3); the electrode sheath (4) is sleeved outside the part of the electrode lead (2) penetrating out of the through hole (3), and one end of the electrode sheath (4) is fixedly connected with one end, far away from the platinum electrode sheet (1), of the electrode support piece (3); 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 part, close to the electrode support (3), of the insulating layer (5) and the electrode lead (2) and outside the electrode sheath (4).
2. The in situ high temperature, high pressure water ORP value sensor of claim 1, wherein the seal assembly comprises a first seal, a second seal, and a third seal; the first sealing member 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) close to the electrode support (3) and the electrode lead (2); the third seal is arranged outside the electrode sheath (4).
3. A sensor of in-situ high temperature and high pressure water ORP value according to claim 2, characterized in that the electrode lead (2) is a platinum wire; the electrode support (3) adopts Al 2 O 3 Insulating ceramic or zirconia ceramic; the insulation layer (5) comprises an insulation temperature-resistant coating layer and an external polytetrafluoroethylene heat shrinkage tube; the first sealing piece adopts a sealing mixed filler composed of a sealing sintering material and solder, and the sealing sintering material adopts glass slurry; the second sealing piece adopts Al 2 O 3 Adhesive and Al 2 O 3 Sealing mixed filler composed of sand; the third sealing element is obtained by co-extruding a graphite gasket with a flange arranged outside the electrode sheath (4) through a flow cell; the electrode sheath (4) is made of C276 hastelloy or 316L stainless steel.
4. The in-situ high temperature and high pressure water ORP value sensor according to claim 1, wherein the diameter of the diversion holes (11) is 1-3 mm, the sizes of a plurality of diversion holes (11) are different, and the platinum electrode plate (1) comprises 2-5 diversion holes (11); the diameter of the through hole (31) is 0.5mm.
5. The in-situ high temperature and high pressure water ORP value sensor of claim 1, wherein the reference electrode (2) is a solid state reference electrode.
6. The in-situ high temperature and high pressure water ORP sensor according to claim 5, wherein the reference electrode (2) is composed of KCl, mgCl.6H 2 O、Al 2 O 3 A solid mixture electrolyte formed by mole ratio, the solid mixture electrolyte being mixed with ZrO 2 A skeleton made of fiber.
7. The processing method of the sensor for the ORP value of the in-situ high-temperature high-pressure water is characterized by comprising the following steps of:
s1: preparing a platinum sheet electrode and an electrode lead, forming a plurality of diversion holes on the platinum sheet electrode, and welding one end of the platinum sheet electrode with one end of the electrode lead;
s2: preparing an electrode support and an electrode sheath, wherein a through hole is formed in the electrode support along the length direction;
s3: the other end of the electrode lead passes through the through hole, the electrode sheath is sleeved outside the part of the electrode lead, which 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 part of the insulating layer, which is close to the electrode support piece, and the electrode lead, and outside the electrode sheath, so as 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 the ORP sensor.
8. The method for processing the in-situ high temperature and high pressure water ORP sensor of claim 7, wherein S4 comprises:
selecting glass slurry with a linear expansion coefficient of 9.7x10 < -6 > (1/℃ C.) as a sealing sintering material, and adding a sealing mixed filler prepared by mixing the sealing sintering material and solder to the end surface of the platinum sheet electrode, which is in contact with the electrode support, so as to obtain a first sealing test piece; heating the first sealing test piece in a heating furnace, and pressurizing the sealing test piece by using a high-pressure air pump to obtain a first sealing piece;
al is added with 2 O 3 Adhesive and Al 2 O 3 Adding the sealing mixed filler prepared by sand mixing to the end surface of the electrode support piece, which is in contact with the motor sheath, so as to obtain a second sealing test piece; heating the second sealing test piece in a heating furnace, and pressurizing the sealing test piece by using a high-pressure air pump to obtain a second sealing piece;
installing a flange outside the motor sheath, and co-extruding a graphite gasket by using the flange and the flow cell to obtain a third sealing element; the first seal, the second seal, and the third seal together comprise the seal assembly.
9. The method for processing the in-situ high-temperature and high-pressure water ORP sensor according to claim 7 or 8, wherein the electrode lead is a platinum wire; the electrode support member adopts Al 2 O 3 Insulating ceramic or zirconia ceramic; the insulation layer comprises an insulation temperature-resistant coating layer and an external polytetrafluoroethylene heat shrinking pipe; the diameter of the diversion holes is 1-3 mm, the sizes of a plurality of diversion holes are different, and the platinum electrode plate comprises 2-5 diversion holes; the diameter of the through hole is 0.5mm.
10. The method for in-situ high-temperature and high-pressure water ORP value is characterized by comprising the following steps of: the ORP value measured by placing the working electrode and the reference electrode of the ORP sensor of any one of claims 1-6 in the same environment.
CN202211489257.9A 2022-11-25 2022-11-25 Method for in-situ high-temperature high-pressure water ORP value, sensor and processing method thereof Pending CN116256403A (en)

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