Boiling nitric acid three-phase corrosion weightlessness experiment device and method in high-temperature reduced-pressure environment

Abstract

The invention discloses a boiling nitric acid three-phase corrosion weightlessness experiment device and method in a high-temperature reduced-pressure environment. The device comprises a reduced-pressure boiling corrosion reaction system, a heating system, a nitric acid steam absorbing and drying system, an air pressure adjusting system and a central control system, the decompression boiling corrosion reaction system is arranged in the heating system; the nitric acid steam absorbing and drying system is connected with the decompression boiling corrosion reaction system through a pipeline; the air pressure adjusting system is in pipeline connection with the nitric acid steam absorbing and drying system; the central control system is electrically connected with the heating system and the air pressure adjusting system. The device can realize high-fidelity simulation and reduction of a high-temperature reduced-pressure environment in a boiling nitric acid corrosion weightlessness experiment, solves the problems of synchronous generation of a nitric acid condensation phase and nitric acid steam, sealing in an experiment process, precise air pressure control and nitric acid tail gas emission treatment, realizes precise simulation of a service environment of a material sample, and improves the test efficiency. And a technical support is provided for researching the boiling nitric acid corrosion resistance and the service life of the material sample in a high-temperature decompression environment.

Description

Technical Field

[0001] The invention belongs to the technical field of material corrosion testing, and in particular relates to a boiling nitric acid three-phase corrosion weight loss experimental device and method under a high-temperature and reduced-pressure environment. Background Art

[0002] In the field of chemical production, boiling nitric acid corrosion in a high-temperature, reduced-pressure environment is often encountered. For example, in the PUREX solvent extraction process of spent fuel reprocessing and regeneration cycles in nuclear reactors, nitric acid is used as a salting-out agent. Boiling nitric acid corrosion in a high-temperature, reduced-pressure environment exists in the evaporator of the main processing equipment. If we want to study the corrosion resistance and service life of the evaporator structural materials under boiling nitric acid conditions in a high-temperature, reduced-pressure environment, it is necessary to conduct a boiling nitric acid three-phase corrosion experiment in a simulated high-temperature, reduced-pressure environment.

[0003] However, there are still many difficulties in safely, accurately and reliably conducting boiling nitric acid three-phase corrosion experiments under high temperature and reduced pressure environments:

[0004] ① Due to the strong corrosiveness of high-temperature nitric acid, the risk of leakage of nitric acid vapor, and the emission treatment of nitric acid tail gas, the experimental device is determined to be not a simple single device, but a complex comprehensive system;

[0005] ② The problem of precise air pressure control needs to be solved during the experiment, because only by maintaining accurate and stable control of air pressure during the experiment can the actual working conditions be accurately simulated;

[0006] ③. Since nitric acid vapor reliquefies and forms a condensed phase at the cold end of the evaporator, the experimental device must solve the problem of how to control the synchronous generation of the nitric acid condensed phase and the nitric acid vapor. If the secondary corrosion effect of the nitric acid condensed phase on the surface of the evaporator structural material is ignored, the pitting initiation at the evaporator head weld cannot be restored, which will lead to insufficient restoration of the working condition and distortion of the corrosion mechanism.

[0007] ④. Since it is necessary to simulate a high-temperature, reduced-pressure environment, how to solve the sealing problem in such an environment is only a difficulty at this stage. Only when the experimental pressure is precisely controlled can a high-fidelity simulation and restoration of the actual high-temperature, reduced-pressure working conditions be achieved.

[0008] Therefore, due to the many difficulties mentioned above, the current research mainly focuses on weight loss experiments in boiling nitric acid under normal pressure, while there are few reports on three-phase corrosion experiments in boiling nitric acid under high temperature and reduced pressure. Summary of the Invention

[0009] In response to the problems existing in the prior art, the present invention provides a boiling nitric acid three-phase corrosion weight loss experimental device and method under a high-temperature and reduced pressure environment, which can achieve high-fidelity simulation and restoration of the high-temperature and reduced pressure environment in the boiling nitric acid corrosion weight loss experiment, solve the problems of synchronous generation of nitric acid condensed phase and nitric acid vapor, sealing during the experiment, precise control of air pressure during the experiment, and emission treatment of nitric acid tail gas, and achieve accurate simulation of the service environment of material samples, providing technical support for studying the corrosion resistance and service life of material samples in boiling nitric acid corrosion under a high-temperature and reduced pressure environment.

[0010] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a boiling nitric acid three-phase corrosion weight loss experimental device under a high-temperature and reduced-pressure environment, comprising a reduced-pressure boiling corrosion reaction system, a heating system, a nitric acid vapor absorption and drying system, an air pressure regulating system and a central control system; the reduced-pressure boiling corrosion reaction system is arranged in the heating system; the nitric acid vapor absorption and drying system is connected to the reduced-pressure boiling corrosion reaction system pipeline; the air pressure regulating system is connected to the nitric acid vapor absorption and drying system pipeline; the central control system is electrically connected to the heating system and the air pressure regulating system respectively.

[0011] The reduced pressure boiling corrosion reaction system includes a reactor body, a reactor cover, a polytetrafluoroethylene hanging sample plate and a condensed phase collection dish; the reactor body is used to hold nitric acid solution; the reactor cover is buckled on top of the reactor body, a polytetrafluoroethylene sealing gasket is provided between the circumferential contact surface of the reactor cover and the reactor body, and the reactor cover and the circumferential mounting edge of the reactor body are compressed and fixed by a quick-release clamp; the polytetrafluoroethylene hanging sample plate is horizontally clamped on the upper end of the reactor body; the condensed phase collection dish is vertically plugged into the polytetrafluoroethylene hanging sample plate.

[0012] A sample hanging plate clamping block is fixedly provided on the inner surface of the reactor body, and the sample hanging plate clamping blocks are evenly distributed along the circumferential direction; sample hanging plate clamping grooves are evenly distributed along the circumferential direction on the edge of the polytetrafluoroethylene sample hanging plate, and the number of sample hanging plate clamping grooves is equal to that of sample hanging plate clamping blocks, and their positions correspond one to one; a sample hanging matrix hole is provided in the middle of the polytetrafluoroethylene sample hanging plate, and a collection dish positioning socket is provided between the sample hanging matrix hole and the sample hanging groove, and the collection dish positioning socket is evenly distributed along the circumferential direction; collection dish positioning pins are evenly distributed along the circumferential direction on the bottom of the condensed phase collection dish, and the number of collection dish positioning pins is equal to that of collection dish positioning sockets, and their positions correspond one to one.

[0013] A circle of water drop-shaped condensed phase drainage beads is fixedly provided on the inner surface of the reactor cover, and the diameter of the inscribed circle of the condensed phase drainage bead circle is smaller than the diameter of the collection port of the condensed phase collection dish.

[0014] The heating system includes an electric heating jacket, a mercury thermometer and a laser reflection temperature measurement cursor; the reactor body is placed inside the electric heating jacket; a thermometer hanging hole is provided on the polytetrafluoroethylene hanging sample plate between the hanging sample matrix hole and the collection dish positioning socket, and the mercury thermometer is connected to the polytetrafluoroethylene hanging sample plate through the thermometer hanging hole; the laser reflection temperature measurement cursor is fixedly mounted above the electric heating jacket through an iron frame.

[0015] The nitric acid vapor absorption drying system includes a condenser, a circulating water tank, a safety bottle, a tail gas absorption bottle and a tail gas absorber; the lower end of the inner tube of the condenser is vertically inserted into the central hole of the reactor cover, and an elbow is installed at the upper end of the inner tube of the condenser; the water inlet of the outer tube of the condenser is connected to the water outlet of the circulating water tank, and the return water outlet of the circulating water tank is connected to the water outlet of the outer tube of the condenser; a three-hole bottle stopper is provided at the bottle mouth of the safety bottle, and a first air guide pipe is connected between the safety bottle and the elbow, and the gas outlet end of the first air guide pipe passes through The exhaust gas absorption bottle is filled with alkaline liquid, and a double-hole stopper is provided at the bottle mouth of the exhaust gas absorption bottle. A second air duct is connected between the exhaust gas absorption bottle and the safety bottle, and the air inlet end of the second air duct passes through the three-hole stopper and extends into the interior of the safety bottle, and the air outlet end of the second air duct passes through the double-hole stopper and extends into the interior of the exhaust gas absorption bottle; a third air duct is connected between the air inlet of the exhaust gas absorber and the exhaust gas absorption bottle, and the air inlet end of the third air duct passes through the double-hole stopper and extends into the interior of the exhaust gas absorption bottle.

[0016] The exhaust gas absorber adopts a solid four-stage filtration structure, which is arranged in the vertical direction as a first-stage filtration unit, a second-stage filtration unit, a third-stage filtration unit and a fourth-stage filtration unit, and a waterproof and breathable diaphragm is provided between adjacent filtration units; the first-stage filtration unit adopts a CaCl2 particle filling structure; the second-stage filtration unit adopts a modified zeolite molecular sieve filling structure; the third-stage filtration unit adopts a mixed filling structure of CaCl2 particles and NaOH particles; the fourth-stage filtration unit adopts a PTFE membrane.

[0017] The air pressure regulating system includes a diaphragm polytetrafluoroethylene vacuum pump and a high-precision vacuum gauge; the air intake of the diaphragm polytetrafluoroethylene vacuum pump is connected to the air outlet of the exhaust gas absorber through a fourth air duct; the high-precision vacuum gauge extends into the interior of the safety bottle through a three-hole bottle stopper.

[0018] The central control system includes a control cabinet, a temperature control module, an air pressure control module, a first polytetrafluoroethylene (PTFE) electrically controlled valve, a second polytetrafluoroethylene (PTFE) electrically controlled valve, a third polytetrafluoroethylene (PTFE) electrically controlled valve, a fourth polytetrafluoroethylene (PTFE) electrically controlled valve, and an online nitrogen oxide detector; the temperature control module and the air pressure control module are both arranged inside the control cabinet; the electric heating sleeve and the laser reflection temperature measurement cursor are both electrically connected to the temperature control module via cables; the first polytetrafluoroethylene (PTFE) electrically controlled valve, the second polytetrafluoroethylene (PTFE) electrically controlled valve, the third polytetrafluoroethylene (PTFE) electrically controlled valve, and the fourth polytetrafluoroethylene (PTFE) electrically controlled valve are respectively installed on the first air duct, the second air duct, the third air duct, and the fourth air duct, and the four valves are all electrically connected to the air pressure control module via cables; the high-precision vacuum gauge is electrically connected to the air pressure control module via cables; the online nitrogen oxide detector is electrically connected to the control cabinet via cables and is located behind the exhaust port of the diaphragm polytetrafluoroethylene (PTFE) vacuum pump to monitor the nitrogen oxide content in the exhaust gas of the diaphragm polytetrafluoroethylene (PTFE) vacuum pump.

[0019] A method for a three-phase corrosion weight loss test in boiling nitric acid under a high-temperature, reduced-pressure environment, using the apparatus for a three-phase corrosion weight loss test in boiling nitric acid under a high-temperature, reduced-pressure environment, comprises the following steps:

[0020] Step 1: Hang the material sample and the mercury thermometer on the polytetrafluoroethylene hanging sample plate respectively, and insert the condensed phase collection dish into the polytetrafluoroethylene hanging sample plate to form a hanging sample assembly;

[0021] Step 2: Move the sample hanging assembly into the reactor body filled with nitric acid solution, and fix the polytetrafluoroethylene sample hanging plate to the reactor body;

[0022] Step 3: Fasten the reactor cover to the upper part of the reactor body, and use a quick-release clamp to press and fix the reactor cover and the reactor body;

[0023] Step 4: Fix the condenser tube to the reactor cover to complete the connection between the condenser tube and the circulating water tank;

[0024] Step 5: Set the experimental target temperature through the temperature control module and set the experimental target pressure through the pressure control module;

[0025] Step 6: Start the electric heating jacket and the diaphragm polytetrafluoroethylene vacuum pump, heat the nitric acid solution in the reactor body through the electric heating jacket, and evacuate and decompress the reactor body through the diaphragm polytetrafluoroethylene vacuum pump until the experimental temperature and experimental pressure reach the target set values. At this time, the nitric acid solution in the reactor body is in a high-temperature, reduced-pressure boiling state;

[0026] Step 7: During the boiling nitric acid three-phase corrosion weight loss experiment of the material sample under high temperature and reduced pressure environment, the temperature control module dynamically adjusts the operating power of the electric heating jacket according to the data feedback from the laser reflection temperature measurement cursor to maintain the stability of the experimental temperature; the air pressure control module dynamically adjusts the operating power of the diaphragm polytetrafluoroethylene vacuum pump and the valve core opening of each polytetrafluoroethylene electric control valve according to the data feedback from the high-precision vacuum gauge to maintain the stability of the experimental air pressure; the online nitrogen oxide detector monitors the nitrogen oxide content of the gas discharged by the diaphragm polytetrafluoroethylene vacuum pump in real time to monitor the cleanliness of the exhaust gas;

[0027] Step 8: After the corrosion weight loss experiment is completed, turn off the electric heating jacket, reversely start the diaphragm polytetrafluoroethylene vacuum pump, and at the same time adjust the valve core opening of each polytetrafluoroethylene electronic control valve to the maximum until the air pressure in the reactor body returns to normal pressure;

[0028] Step 9: Remove the quick-release clamp to release the pressure fixation between the reactor cover and the reactor body, then remove the reactor cover from the reactor body, remove the sample hanging assembly from the reactor body, and finally remove the material sample from the polytetrafluoroethylene hanging sample plate.

[0029] Beneficial effects of the present invention:

[0030] The present invention discloses a boiling nitric acid three-phase corrosion weight loss experimental device and method under a high-temperature and reduced-pressure environment. The device as a whole adopts a modular design concept and has the characteristics of convenient disassembly, assembly and re-modification. A diaphragm polytetrafluoroethylene vacuum pump is used as a pressure reduction adjustment execution device, which can not only achieve precise control of air pressure, but also reduce vibration during the vacuuming and decompression process, thereby improving the operational safety of the device. Through a specially designed polytetrafluoroethylene hanging sample plate, the corrosion test of the material sample in any single phase of nitric acid can be realized by adjusting the hanging height of the sample, and the corrosion test of the material sample under arbitrary coupling of the three phases of nitric acid can also be realized, thereby effectively improving the experimental efficiency.

[0031] The present invention discloses a boiling nitric acid three-phase corrosion weight loss experimental device and method under a high-temperature and reduced-pressure environment. The tail gas absorber in the device adopts a solid four-stage filtration structure. On the one hand, it can provide gas purification for the entire device to protect the operating safety of the rear diaphragm polytetrafluoroethylene vacuum pump. On the other hand, through the design of the sieve interlayer and the application of a waterproof and breathable diaphragm, the pressure drop loss in the device during vacuuming is effectively reduced, providing favorable conditions for stabilizing the air pressure in the device. By adopting a combination of a mercury thermometer and a laser reflection temperature measurement cursor to measure temperature, the problems of indirect and inaccurate temperature measurement in the traditional temperature measurement method of combining a temperature measuring sleeve and a temperature sensor are avoided.

[0032] The apparatus and method for the three-phase corrosion weight loss experiment in boiling nitric acid under a high-temperature and reduced-pressure environment of the present invention can accurately implement the three-phase corrosion behavior of materials in a reduced-pressure boiling nitric acid corrosion environment, for example, simulating the reduced-pressure boiling nitric acid corrosion environment during the operation of a spent fuel reprocessing evaporator, or simulating the corrosion behavior of mechanical parts or metal components of equipment used in processes such as reduced-pressure evaporation and reduced-pressure distillation. Not only can the corrosion resistance and service life of materials in relevant environments be evaluated, but it can also serve as an experimental apparatus for basic research such as studying the saturated vapor pressure of substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the structure of the boiling nitric acid three-phase corrosion weight loss experimental device under high temperature and reduced pressure environment of the present invention;

[0034] Figure 2 This is a schematic structural diagram of the assembly of the reactor body, reactor cover, polytetrafluoroethylene hanging sample, mercury thermometer, condenser and elbow of the present invention;

[0035] Figure 3 It is a structural schematic diagram of the polytetrafluoroethylene hanging sample of the present invention;

[0036] In the figure, 1 is the reactor body, 2 is the reactor cover, 3 is the polytetrafluoroethylene hanging sample plate, 4 is the condensed phase collection dish, 5 is the hanging sample plate mounting groove, 6 is the hanging sample matrix hole, 7 is the collection dish positioning socket, 8 is the electric heating jacket, 9 is the mercury thermometer, 10 is the laser reflection temperature measurement cursor, 11 is the thermometer hanging hole, 12 is the condenser, 13 is the circulating water tank, 14 is the safety bottle, 15 is the tail gas absorption bottle, 16 is the tail gas absorber, 17 is the elbow, 18 is the first gas guide Tube, 19—second air guide tube, 20—third air guide tube, 21—diaphragm polytetrafluoroethylene vacuum pump, 22—high-precision vacuum gauge, 23—fourth air guide tube, 24—control cabinet, 25—temperature control module, 26—air pressure control module, 27—first polytetrafluoroethylene electric control valve, 28—second polytetrafluoroethylene electric control valve, 29—third polytetrafluoroethylene electric control valve, 30—fourth polytetrafluoroethylene electric control valve, 31—online nitrogen oxide detector. DETAILED DESCRIPTION

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] like Figures 1 to 3As shown, a boiling nitric acid three-phase corrosion weight loss experimental device under a high-temperature and reduced-pressure environment includes a reduced-pressure boiling corrosion reaction system, a heating system, a nitric acid vapor absorption and drying system, an air pressure regulating system and a central control system; the reduced-pressure boiling corrosion reaction system is arranged in the heating system; the nitric acid vapor absorption and drying system is connected to the reduced-pressure boiling corrosion reaction system pipeline; the air pressure regulating system is connected to the nitric acid vapor absorption and drying system pipeline; the central control system is electrically connected to the heating system and the air pressure regulating system respectively.

[0039] In this embodiment, the boiling nitric acid three-phase corrosion weight loss experimental apparatus under high temperature and reduced pressure environment is entirely set in a walk-in fume hood.

[0040] The reduced pressure boiling corrosion reaction system includes a reactor body 1, a reactor cover 2, a polytetrafluoroethylene hanging sample plate 3 and a condensed phase collection dish 4; the reactor body 1 is used to hold nitric acid solution; the reactor cover 2 is buckled on top of the reactor body 1, and a polytetrafluoroethylene sealing gasket is provided between the circumferential contact surface of the reactor cover 2 and the reactor body 1, and the reactor cover 2 and the circumferential mounting edge of the reactor body 1 are tightened and fixed by a quick-release clamp; the polytetrafluoroethylene hanging sample plate 3 is horizontally clamped on the upper end of the reactor body 1; the condensed phase collection dish 4 is vertically inserted above the polytetrafluoroethylene hanging sample plate 3.

[0041] A sample hanging plate clamping block is fixedly provided on the inner surface of the reactor body 1, and the sample hanging plate clamping blocks are evenly distributed along the circumferential direction; sample hanging plate clamping grooves 5 are evenly distributed along the circumferential direction on the edge of the polytetrafluoroethylene sample hanging plate 3, and the number of sample hanging plate clamping grooves 5 is equal to that of sample hanging plate clamping blocks and their positions correspond one to one; a sample hanging matrix hole 6 is provided in the middle of the polytetrafluoroethylene sample hanging plate 3, and a collection dish positioning socket 7 is provided between the sample hanging matrix hole 6 and the sample hanging groove 5, and the collection dish positioning socket 7 is evenly distributed along the circumferential direction; collection dish positioning pins are evenly distributed along the circumferential direction on the bottom of the condensed phase collection dish 4, and the number of collection dish positioning pins is equal to that of the collection dish positioning socket 7 and their positions correspond one to one.

[0042] A circle of water drop-shaped condensed phase drainage beads is fixedly provided on the inner surface of the reactor cover 2 , and the diameter of the inscribed circle of the condensed phase drainage beads is smaller than the diameter of the collection port of the condensed phase collection dish 4 .

[0043] In the present embodiment, the materials of the reactor body 1, the reactor cover 2 and the sample hanging card block are all high-strength boron glass, the number of the sample hanging card blocks is four, and the sample hanging card block is fixedly bonded to the inner surface of the reactor body 1 by thermal bonding; the number of the collecting dish positioning jacks 7 is four; the number of the condensed phase drainage beads is ten, and the condensed phase drainage beads are fixedly bonded to the inner surface of the reactor cover 2 by thermal bonding; the matrix specification of the sample hanging matrix hole 6 is 15×16, that is, a total of 240 sample hanging single holes are included, and every four sample hanging single holes are a group, the vertical sample hanging single hole groups are marked with letters, and the horizontal sample hanging single hole groups are marked with Arabic numerals; when hanging samples, each sample hanging single hole group can hang one sample or a string of samples, and the sample can be completely invaded into the nitric acid solution, semi-invaded into the nitric acid solution, or not invaded into the nitric acid solution by adjusting the hanging height of the sample, thereby realizing liquid phase corrosion, gas-liquid two-phase synchronous corrosion or gas phase corrosion of the sample.

[0044] The heating system includes an electric heating sleeve 8, a mercury thermometer 9 and a laser reflection temperature measurement cursor 10; the reactor body 1 is placed on the inside of the electric heating sleeve 8; a thermometer hanging hole 11 is provided on the polytetrafluoroethylene hanging sample plate 3 between the hanging sample matrix hole 6 and the collection dish positioning socket 7, and the mercury thermometer 9 is hung and connected to the polytetrafluoroethylene hanging sample plate 3 through the thermometer hanging hole 11; the laser reflection temperature measurement cursor 10 is fixedly mounted above the electric heating sleeve 8 through an iron frame.

[0045] In this embodiment, the operating wavelength of the laser reflection temperature measurement cursor 10 is 1550nm, and its reflector group is made of diamond-coated sapphire material. The temperature measurement range is 0-150°C, the temperature measurement accuracy is ±0.3°C, and the response time is ≤50ms. During temperature measurement, the laser reflection temperature measurement cursor 10 collects the mercury column height of the mercury thermometer 9, and the temperature control module 25 of the central control system automatically converts the mercury column height data into temperature data. Based on the measured temperature data, the temperature control module 25 accurately controls the heating temperature of the electric heating sleeve 8.

[0046] The nitric acid vapor absorption and drying system includes a condenser 12, a circulating water tank 13, a safety bottle 14, a tail gas absorption bottle 15 and a tail gas absorber 16; the lower end of the inner tube of the condenser 12 is vertically inserted into the central hole of the reactor cover 2, and an elbow 17 is installed at the upper end of the inner tube of the condenser 12; the outer tube water inlet of the condenser 12 is connected to the water outlet of the circulating water tank 13, and the return water port of the circulating water tank 13 is connected to the outer tube water outlet of the condenser 12; a three-hole bottle stopper is provided at the bottle mouth of the safety bottle 14, and a first air guide pipe 18 is connected between the safety bottle 14 and the elbow 17, and the gas outlet of the first air guide pipe 18 is connected to the outer tube of the condenser 12. The end passes through the three-hole stopper and extends into the interior of the safety bottle 14; the interior of the tail gas absorption bottle 15 is filled with alkaline liquid, and a double-hole stopper is provided at the bottle mouth of the tail gas absorption bottle 15. A second air duct 19 is connected between the tail gas absorption bottle 15 and the safety bottle 14, and the air inlet end of the second air duct 19 passes through the three-hole stopper and extends into the interior of the safety bottle 14, and the air outlet end of the second air duct 19 passes through the double-hole stopper and extends into the interior of the tail gas absorption bottle 15; a third air duct 20 is connected between the air inlet of the tail gas absorber 16 and the tail gas absorption bottle 15, and the air inlet end of the third air duct 20 passes through the double-hole stopper and extends into the interior of the tail gas absorption bottle 15.

[0047] In this embodiment, the center hole of the reactor cover 2 is a frosted structure; the alkaline liquid filled in the tail gas absorption bottle 15 is a saturated solution of Na2CO3, which can perform double decomposition of HNO3 in the tail gas and react to generate CO2.

[0048] The exhaust gas absorber 16 adopts a solid four-stage filtration structure, which is arranged in the vertical direction as a first-stage filtration unit, a second-stage filtration unit, a third-stage filtration unit and a fourth-stage filtration unit, and a waterproof and breathable diaphragm is provided between adjacent filtration units; the first-stage filtration unit adopts a CaCl2 particle filling structure; the second-stage filtration unit adopts a modified zeolite molecular sieve filling structure; the third-stage filtration unit adopts a mixed filling structure of CaCl2 particles and NaOH particles; the fourth-stage filtration unit adopts a PTFE membrane.

[0049] In this embodiment, the waterproof and breathable membrane is made of GORE-TEX fabric, the porosity of the PTFE membrane is 85%, the first-stage filter unit is filled with CaCl2 particles for drying the exhaust gas, and the second-stage filter unit is filled with modified zeolite molecular sieve for NO X The third-stage filter unit is used for physical adsorption of HNO3 and CO2 through a mixture of filled CaCl2 particles and NaOH particles and further dries the exhaust gas. The PTFE membrane of the fourth-stage filter unit is used to filter solid particles in the exhaust gas.

[0050] The air pressure regulating system includes a diaphragm polytetrafluoroethylene vacuum pump 21 and a high-precision vacuum gauge 22; the air intake of the diaphragm polytetrafluoroethylene vacuum pump 21 is connected to the air outlet of the exhaust absorber 16 through a fourth air duct 23; the high-precision vacuum gauge 22 extends into the interior of the safety bottle 14 through a three-hole stopper.

[0051] In this embodiment, the port on the three-hole bottle stopper for inserting the high-precision vacuum gauge 22 is covered with a PTFE membrane at its upper end, and a filter tube is provided at its lower end, which is filled with activated carbon particles and CaCl2 particles; the high-precision vacuum gauge 22 is connected to the port of the three-hole bottle stopper in a threaded manner, and a polytetrafluoroethylene gasket is installed at the connection for sealing, and the high-precision vacuum gauge 22 needs to undergo three-proof treatment before the experiment; the diaphragm polytetrafluoroethylene vacuum pump 21 is fixed to the experimental frame by external pins and a shock-absorbing base liner.

[0052] The central control system includes a control cabinet 24, a temperature control module 25, an air pressure control module 26, a first polytetrafluoroethylene electric control valve 27, a second polytetrafluoroethylene electric control valve 28, a third polytetrafluoroethylene electric control valve 29, a fourth polytetrafluoroethylene electric control valve 30 and an online nitrogen oxide detector 31; the temperature control module 25 and the air pressure control module 26 are both arranged inside the control cabinet 24; the electric heating sleeve 8 and the laser reflection temperature measurement cursor 10 are both electrically connected to the temperature control module 25 through cables; the first polytetrafluoroethylene electric control valve 27, the second polytetrafluoroethylene electric control valve 28, the third polytetrafluoroethylene electric control valve 29, the ... The polytetrafluoroethylene electric-controlled valve 29 and the fourth polytetrafluoroethylene electric-controlled valve 30 are respectively installed on the first air duct 18, the second air duct 19, the third air duct 20 and the fourth air duct 23, and the four valves are electrically connected to the air pressure control module 26 through cables; the high-precision vacuum gauge 22 is electrically connected to the air pressure control module 26 through cables; the online nitrogen oxide detector 31 is electrically connected to the control cabinet 24 through cables, and the online nitrogen oxide detector 31 is located behind the exhaust port of the diaphragm polytetrafluoroethylene vacuum pump 21, and is used to monitor the nitrogen oxide content in the exhaust gas of the diaphragm polytetrafluoroethylene vacuum pump 21.

[0053] In this embodiment, the temperature control module 25 has a photoelectric coding reading function, which can convert the mercury column height of the mercury thermometer 9 into a standard signal of 4mA to 20mA for output, and also has a vibration compensation function. When the diaphragm polytetrafluoroethylene vacuum pump 21 is working and causes the vibration frequency of the entire experimental device to be greater than 30Hz, digital filtering can be automatically performed; the laser reflection temperature measurement cursor 10 is used to feed back the measured data to the temperature control module 25 in real time. The temperature control module 25 can adjust the operating power and start and stop state of the electric heating sleeve 8 according to the real-time measured temperature of the nitric acid solution to ensure the stability of the high temperature state; high precision The vacuum gauge 22 is used to feed back the vacuum data in the pipeline chamber system to the air pressure control module 26 in real time. The air pressure control module 26 can adjust the operating power and start and stop status of the diaphragm polytetrafluoroethylene vacuum pump 21 and the valve core opening of the four valves based on the real-time feedback vacuum data to ensure the stability of the decompression state; the first polytetrafluoroethylene electric-controlled valve 27, the second polytetrafluoroethylene electric-controlled valve 28, the third polytetrafluoroethylene electric-controlled valve 29 and the fourth polytetrafluoroethylene electric-controlled valve 30 are valves of the same model, the valve core opening control resolution of the valve is 0.1°, and the inner wall of the valve flow channel is provided with a spiral guide groove.

[0054] A method for a three-phase corrosion weight loss test in boiling nitric acid under a high-temperature, reduced-pressure environment, using the apparatus for a three-phase corrosion weight loss test in boiling nitric acid under a high-temperature, reduced-pressure environment, comprises the following steps:

[0055] Step 1: hang the material sample and the mercury thermometer 9 on the polytetrafluoroethylene hanging sample plate 3 respectively, and insert the condensed phase collection dish 4 on the polytetrafluoroethylene hanging sample plate 3 to form a hanging sample assembly;

[0056] Step 2: Move the sample hanging assembly into the reactor body 1 filled with nitric acid solution, and fix the polytetrafluoroethylene sample hanging plate 3 to the reactor body 1;

[0057] Step 3: Fasten the reactor cover 2 onto the upper part of the reactor body 1, and use a quick-release clamp to press and fix the reactor cover 2 and the reactor body 1;

[0058] Step 4: Fix the condenser tube 12 to the reactor cover 2 to connect the condenser tube 12 to the circulating water tank 13;

[0059] Step 5: Set the experimental target temperature through the temperature control module 25 and set the experimental target pressure through the pressure control module 26;

[0060] Step 6: Start the electric heating jacket 8 and the diaphragm polytetrafluoroethylene vacuum pump 21 to heat the nitric acid solution in the reactor body 1 through the electric heating jacket 8, and evacuate and reduce the pressure of the reactor body 1 through the diaphragm polytetrafluoroethylene vacuum pump 21 until the experimental temperature and the experimental pressure reach the target set values. At this time, the nitric acid solution in the reactor body 1 is in a high-temperature, reduced-pressure boiling state;

[0061] Step 7: During the boiling nitric acid three-phase corrosion weight loss experiment of the material sample under high temperature and reduced pressure environment, the temperature control module 25 dynamically adjusts the operating power of the electric heating jacket 8 according to the data fed back by the laser reflection temperature measurement cursor 10 to maintain the stability of the experimental temperature; the air pressure control module 26 dynamically adjusts the operating power of the diaphragm polytetrafluoroethylene vacuum pump 21 and the valve core opening of each polytetrafluoroethylene electric control valve according to the data fed back by the high-precision vacuum gauge 22 to maintain the stability of the experimental air pressure; the online nitrogen oxide detector 31 performs real-time monitoring of the nitrogen oxide content in the gas discharged by the diaphragm polytetrafluoroethylene vacuum pump 21 to monitor the cleanliness of the exhaust gas;

[0062] Step 8: After the corrosion weight loss experiment is completed, the electric heating jacket 8 is turned off, the diaphragm polytetrafluoroethylene vacuum pump 21 is reversely started, and the valve core opening of each polytetrafluoroethylene electric control valve is adjusted to the maximum until the air pressure in the reactor body 1 returns to normal pressure;

[0063] Step 9: Remove the quick-release clamp to release the pressure fixation between the reactor cover 2 and the reactor body 1, then remove the reactor cover 2 from the reactor body 1, remove the sample hanging assembly from the reactor body 1, and finally remove the material sample from the polytetrafluoroethylene hanging sample plate 3.

[0064] The solutions in the embodiments are not intended to limit the scope of protection of the present invention. All equivalent implementations or modifications that do not depart from the scope of protection of the present invention are included in the scope of protection of the present invention.

Claims

1. A three-phase nitric acid corrosion weight loss test device under high temperature and reduced pressure environment, characterized by: It includes a reduced pressure boiling corrosion reaction system, a heating system, a nitric acid vapor absorption and drying system, an air pressure regulating system and a central control system; the reduced pressure boiling corrosion reaction system is arranged in the heating system; the nitric acid vapor absorption and drying system is connected to the reduced pressure boiling corrosion reaction system pipeline; the air pressure regulating system is connected to the nitric acid vapor absorption and drying system pipeline; the central control system is electrically connected to the heating system and the air pressure regulating system respectively.

2. The apparatus for three-phase corrosion weight loss experiment in boiling nitric acid under high temperature and reduced pressure environment according to claim 1, characterized in that: The reduced pressure boiling corrosion reaction system includes a reactor body, a reactor cover, a polytetrafluoroethylene hanging sample plate and a condensed phase collection dish; the reactor body is used to hold nitric acid solution; the reactor cover is buckled on top of the reactor body, a polytetrafluoroethylene sealing gasket is provided between the circumferential contact surface of the reactor cover and the reactor body, and the reactor cover and the circumferential mounting edge of the reactor body are compressed and fixed by a quick-release clamp; the polytetrafluoroethylene hanging sample plate is horizontally clamped on the upper end of the reactor body; the condensed phase collection dish is vertically plugged into the polytetrafluoroethylene hanging sample plate.

3. The apparatus for three-phase corrosion weight loss experiment in boiling nitric acid under high temperature and reduced pressure environment according to claim 2, characterized in that: A sample hanging plate clamping block is fixedly provided on the inner surface of the reactor body, and the sample hanging plate clamping blocks are evenly distributed along the circumferential direction; sample hanging plate clamping grooves are evenly distributed along the circumferential direction on the edge of the polytetrafluoroethylene sample hanging plate, and the number of sample hanging plate clamping grooves is equal to that of sample hanging plate clamping blocks, and their positions correspond one to one; a sample hanging matrix hole is provided in the middle of the polytetrafluoroethylene sample hanging plate, and a collection dish positioning socket is provided between the sample hanging matrix hole and the sample hanging groove, and the collection dish positioning socket is evenly distributed along the circumferential direction; collection dish positioning pins are evenly distributed along the circumferential direction on the bottom of the condensed phase collection dish, and the number of collection dish positioning pins is equal to that of collection dish positioning sockets, and their positions correspond one to one.

4. The apparatus for three-phase corrosion weight loss experiment in boiling nitric acid under high temperature and reduced pressure environment according to claim 2, characterized in that: A circle of water drop-shaped condensed phase drainage beads is fixedly provided on the inner surface of the reactor cover, and the diameter of the inscribed circle of the condensed phase drainage bead circle is smaller than the diameter of the collection port of the condensed phase collection dish.

5. The apparatus for three-phase corrosion weight loss experiment in boiling nitric acid under high temperature and reduced pressure environment according to claim 2, characterized in that: The heating system includes an electric heating jacket, a mercury thermometer and a laser reflection temperature measurement cursor; the reactor body is placed inside the electric heating jacket; a thermometer hanging hole is provided on the polytetrafluoroethylene hanging sample plate between the hanging sample matrix hole and the collection dish positioning socket, and the mercury thermometer is connected to the polytetrafluoroethylene hanging sample plate through the thermometer hanging hole; the laser reflection temperature measurement cursor is fixedly mounted above the electric heating jacket through an iron frame.

6. The apparatus for three-phase corrosion weight loss experiment in boiling nitric acid under high temperature and reduced pressure environment according to claim 2, characterized in that: The nitric acid vapor absorption drying system includes a condenser, a circulating water tank, a safety bottle, a tail gas absorption bottle and a tail gas absorber; the lower end of the inner tube of the condenser is vertically inserted into the central hole of the reactor cover, and an elbow is installed at the upper end of the inner tube of the condenser; the water inlet of the outer tube of the condenser is connected to the water outlet of the circulating water tank, and the return water outlet of the circulating water tank is connected to the water outlet of the outer tube of the condenser; a three-hole bottle stopper is provided at the bottle mouth of the safety bottle, and a first air guide pipe is connected between the safety bottle and the elbow, and the gas outlet end of the first air guide pipe passes through The exhaust gas absorption bottle is filled with alkaline liquid, and a double-hole stopper is provided at the bottle mouth of the exhaust gas absorption bottle. A second air duct is connected between the exhaust gas absorption bottle and the safety bottle, and the air inlet end of the second air duct passes through the three-hole stopper and extends into the interior of the safety bottle, and the air outlet end of the second air duct passes through the double-hole stopper and extends into the interior of the exhaust gas absorption bottle; a third air duct is connected between the air inlet of the exhaust gas absorber and the exhaust gas absorption bottle, and the air inlet end of the third air duct passes through the double-hole stopper and extends into the interior of the exhaust gas absorption bottle.

7. The apparatus for three-phase corrosion weight loss experiment in boiling nitric acid under high temperature and reduced pressure environment according to claim 6, characterized in that: The exhaust gas absorber adopts a solid four-stage filtration structure, which is arranged in the vertical direction as a first-stage filtration unit, a second-stage filtration unit, a third-stage filtration unit and a fourth-stage filtration unit, and a waterproof and breathable diaphragm is provided between adjacent filtration units; the first-stage filtration unit adopts a CaCl2 particle filling structure; the second-stage filtration unit adopts a modified zeolite molecular sieve filling structure; the third-stage filtration unit adopts a mixed filling structure of CaCl2 particles and NaOH particles; the fourth-stage filtration unit adopts a PTFE membrane.

8. The apparatus for three-phase corrosion weight loss experiment in boiling nitric acid under high temperature and reduced pressure environment according to claim 6, characterized in that: The air pressure regulating system includes a diaphragm polytetrafluoroethylene vacuum pump and a high-precision vacuum gauge; the air intake of the diaphragm polytetrafluoroethylene vacuum pump is connected to the air outlet of the exhaust gas absorber through a fourth air duct; the high-precision vacuum gauge extends into the interior of the safety bottle through a three-hole bottle stopper.

9. The apparatus for three-phase corrosion weight loss experiment in boiling nitric acid under high temperature and reduced pressure environment according to claim 8, characterized in that: The central control system includes a control cabinet, a temperature control module, an air pressure control module, a first polytetrafluoroethylene (PTFE) electrically controlled valve, a second polytetrafluoroethylene (PTFE) electrically controlled valve, a third polytetrafluoroethylene (PTFE) electrically controlled valve, a fourth polytetrafluoroethylene (PTFE) electrically controlled valve, and an online nitrogen oxide detector; the temperature control module and the air pressure control module are both arranged inside the control cabinet; the electric heating sleeve and the laser reflection temperature measurement cursor are both electrically connected to the temperature control module via cables; the first polytetrafluoroethylene (PTFE) electrically controlled valve, the second polytetrafluoroethylene (PTFE) electrically controlled valve, the third polytetrafluoroethylene (PTFE) electrically controlled valve, and the fourth polytetrafluoroethylene (PTFE) electrically controlled valve are respectively installed on the first air duct, the second air duct, the third air duct, and the fourth air duct, and the four valves are all electrically connected to the air pressure control module via cables; the high-precision vacuum gauge is electrically connected to the air pressure control module via cables; the online nitrogen oxide detector is electrically connected to the control cabinet via cables and is located behind the exhaust port of the diaphragm polytetrafluoroethylene (PTFE) vacuum pump to monitor the nitrogen oxide content in the exhaust gas of the diaphragm polytetrafluoroethylene (PTFE) vacuum pump.

10. A method for a three-phase corrosion weight loss test in boiling nitric acid under a high-temperature, reduced-pressure environment, using the apparatus for a three-phase corrosion weight loss test in boiling nitric acid under a high-temperature, reduced-pressure environment as claimed in claim 9, characterized in that: The steps include: Step 1: Hang the material sample and the mercury thermometer on the polytetrafluoroethylene hanging sample plate respectively, and insert the condensed phase collection dish into the polytetrafluoroethylene hanging sample plate to form a hanging sample assembly; Step 2: Move the sample hanging assembly into the reactor body filled with nitric acid solution, and fix the polytetrafluoroethylene sample hanging plate to the reactor body; Step 3: Fasten the reactor cover to the upper part of the reactor body, and use a quick-release clamp to press and fix the reactor cover and the reactor body; Step 4: Fix the condenser tube to the reactor cover to complete the connection between the condenser tube and the circulating water tank; Step 5: Set the experimental target temperature through the temperature control module and set the experimental target pressure through the pressure control module; Step 6: Start the electric heating jacket and the diaphragm polytetrafluoroethylene vacuum pump, heat the nitric acid solution in the reactor body through the electric heating jacket, and evacuate and decompress the reactor body through the diaphragm polytetrafluoroethylene vacuum pump until the experimental temperature and experimental pressure reach the target set values. At this time, the nitric acid solution in the reactor body is in a high-temperature, reduced-pressure boiling state; Step 7: During the boiling nitric acid three-phase corrosion weight loss experiment of the material sample under high temperature and reduced pressure environment, the temperature control module dynamically adjusts the operating power of the electric heating jacket according to the data feedback from the laser reflection temperature measurement cursor to maintain the stability of the experimental temperature; the air pressure control module dynamically adjusts the operating power of the diaphragm polytetrafluoroethylene vacuum pump and the valve core opening of each polytetrafluoroethylene electric control valve according to the data feedback from the high-precision vacuum gauge to maintain the stability of the experimental air pressure; the online nitrogen oxide detector monitors the nitrogen oxide content of the gas discharged by the diaphragm polytetrafluoroethylene vacuum pump in real time to monitor the cleanliness of the exhaust gas; Step 8: After the corrosion weight loss experiment is completed, turn off the electric heating jacket, reversely start the diaphragm polytetrafluoroethylene vacuum pump, and at the same time adjust the valve core opening of each polytetrafluoroethylene electronic control valve to the maximum until the air pressure in the reactor body returns to normal pressure; Step 9: Remove the quick-release clamp to release the pressure fixation between the reactor cover and the reactor body, then remove the reactor cover from the reactor body, remove the sample hanging assembly from the reactor body, and finally remove the material sample from the polytetrafluoroethylene hanging sample plate.

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