Device and method for monitoring corrosion inhibition and oxide film peeling of supercritical CO2 circulating heating surface

Abstract

The present invention discloses a device and method for monitoring corrosion inhibition and oxide film peeling of a supercritical CO2 cycle heating surface. The working fluid is sampled at the place where oxide scale peeling occurs. After passing through a pressure reducing valve and a cooler to become a low-temperature and low-pressure working fluid, the concentrations of carbon dioxide, carbon monoxide, and oxygen are monitored by a gas analyzer and displayed on a computer host. The host compares the monitoring results with the carbon monoxide concentration threshold obtained in a preliminary experiment, and issues an alarm to the crew when an abnormal carbon monoxide concentration occurs. This monitoring device utilizes the mechanism that the carbon monoxide concentration increases when the oxide scale cracks and peels off. Compared with methods such as monitoring the working fluid temperature, the present invention is accurate and reliable, with a short response time. By monitoring different monitoring locations, the location of oxide scale peeling can be accurately determined. In addition, the monitoring equipment is mature, the monitoring cost is low, and it is suitable for supercritical carbon dioxide systems of different pressures.

Description

Technical Field

[0001] The present invention belongs to the technical field of supercritical carbon dioxide, and in particular relates to a device and method for monitoring corrosion inhibition and oxide film peeling of a supercritical CO2 circulating heating surface. Background Art

[0002] With the continuous development of science and technology, researchers are increasingly focusing on how to efficiently utilize energy, including in-depth research on circulating working fluids. Carbon dioxide is a colorless, odorless, non-toxic, non-flammable, and stable gas with a critical temperature of 31°C and a critical pressure of 7.38 MPa. When carbon dioxide is in a supercritical state, it exhibits a coexistence of gaseous and liquid states. In this state, the density and compressibility of supercritical carbon dioxide are approximately equal to those of liquid carbon dioxide, the viscosity is approximately equal to that of gaseous carbon dioxide, and the specific heat capacity and thermal conductivity are greater than those of gaseous carbon dioxide. Therefore, compared to other working fluids, supercritical carbon dioxide systems have the advantages of compact structure, high cycle efficiency, stable properties, wide applicability, and environmental friendliness. They can be used in fields such as solar energy and nuclear energy, and currently represent one of the power generation cycles with the greatest development potential.

[0003] Research on supercritical CO2 systems sparked a wave of enthusiasm as early as the 1960s. However, due to a lack of key technological breakthroughs at the time, such as pipeline materials unable to withstand high temperatures and high pressures, and heat exchanger efficiency failing to meet system requirements, they were not widely adopted. With technological and material innovations, new developments have been made in pipeline materials and heat exchanger efficiency, prompting researchers both domestically and internationally to re-evaluate and study supercritical CO2 systems. Michael proposed three designs for supercritical CO2-cooled fast reactors, with the high-performance option achieving a net efficiency of 49%. In 2004, Dostal V et al., with support from Sandia Laboratories in the United States, conducted a comprehensive evaluation of supercritical CO2 systems for nuclear power generation, including overall system layout, efficiency, feasibility, and economics. They found that when the supercritical CO2 temperature at the turbine inlet was 550°C and the pressure was 20 MPa, the supercritical CO2 recompression cycle achieved a thermal efficiency of 45.3%, and its construction cost was 18% lower than that of a steam Rankine cycle. Consequently, countries such as the United States and Japan began conducting experimental and theoretical research on supercritical CO2 systems. In order to achieve higher cycle thermal efficiency, the temperature and pressure of supercritical carbon dioxide are getting higher and higher, leading to another technical problem - oxide scale peeling.

[0004] As the operating temperature of supercritical CO2 increases, the requirements for the high-temperature resistance of pipe walls become increasingly stringent. For example, in a photothermal cycle, the working fluid temperature can reach as high as 800°C. Therefore, researchers are paying close attention to the issue of oxide scale flaking caused by factors such as pipe wall overheating. In high-temperature pipes, surface oxide scale flakes off after reaching a critical flaking thickness and accumulates in the U-bend. This reduces the working fluid flow area, lowers the heat transfer coefficient, and increases the temperature difference between the working fluid and the pipe wall, leading to overheating and pipe bursts on the system's high-temperature heating surfaces. The oxidation-carbonization effect of supercritical CO2 weakens the adhesion of oxidation products on the pipe surface, further causing oxide scale flaking and resulting in significant economic losses. Furthermore, turbine blades and nozzles are subject to wear and erosion from flaked oxide scale particles, leading to valve sticking and blade damage. This severely reduces turbine efficiency, jeopardizes the normal operation of the turbine, shortens the service life of the system and the turbine, and can lead to major safety accidents.

[0005] Therefore, in order to improve the service life and working efficiency of the supercritical carbon dioxide system and ensure its safe use, it is urgent to find preventive measures for oxide scale peeling.

[0006] At present, the existing solutions to the problem of oxide scale peeling inside supercritical carbon dioxide pipelines mainly include the following three methods: (1) appropriately monitoring and adjusting the heat source operating conditions to reduce temperature deviation; (2) monitoring the working fluid temperature and strictly prohibiting over-temperature operation; (3) controlling the temperature change rate of the working fluid during variable load conditions such as system start-up and shutdown, peak regulation, etc., to avoid concentrated oxide scale peeling caused by sudden changes in the working fluid temperature.

[0007] These methods can reduce the degree of oxide scale peeling to a certain extent, but they have certain limitations. Methods (1) and (2) both control the working fluid temperature and have a certain preventive effect, but the metal pipe wall temperature is generally 35-50℃ higher than the working fluid temperature, and the metal wall temperature cannot be directly monitored. Therefore, it is easy to cause the pipe wall to overheat, and it is impossible to directly reflect the oxide scale peeling. Method (3) only plays a certain role in the process of variable load conditions such as start-stop and peak regulation, and cannot play a preventive and control role in the peeling of oxide scale during stable operation of the system. Therefore, it is necessary to study a new monitoring method to monitor the oxide scale peeling in the pipe in real time. Summary of the Invention

[0008] In response to the problem of oxide scale peeling in supercritical carbon dioxide internal pipes, the purpose of the present invention is to propose a real-time monitoring device and method for judging the oxide scale peeling situation by monitoring the change in carbon monoxide concentration in the supercritical carbon dioxide working environment. The present invention utilizes the oxidation-carbonization mechanism of supercritical carbon dioxide. When the oxide film is cracked and peeled off due to factors such as thermal stress, the oxide film on the surface of the pipe is regenerated. During this stage, the metal pipe reacts with carbon dioxide to produce oxides, and continuously produces carbon monoxide and carbon. The generated activated carbon diffuses into the interior of the matrix, and the carbonization depth increases. And because carbon reacts with carbon dioxide, the concentration of carbon monoxide will increase again. Therefore, the peeling of oxide scale inside the metal pipe wall will inevitably cause an increase in carbon monoxide concentration. By measuring the change in carbon monoxide concentration in the carbon dioxide working environment through some real-time monitoring devices, the peeling situation of oxide scale inside the high-temperature pipe can be judged.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A monitoring device for corrosion inhibition and oxide film peeling on heated surfaces in a supercritical CO2 cycle, comprising a sampling pipeline connected to a high-temperature superheater 12 in a supercritical CO2 system near the pipeline inlet, the middle of the pipeline, near the pipeline outlet, and at locations prone to oxide film peeling. A pressure reducing valve 11, a cooler 7, a gas flowmeter 10, and a gas analyzer 9 are sequentially arranged on the sampling pipeline. The pressure reducing valve 11 reduces the pressure of the sampled working fluid, and the reduced-pressure sampled working fluid enters the cooler 7 for cooling. The gas flowmeter 10, arranged between the cooler 7 and the gas analyzer 9, controls the flow rate of the working fluid and connects the outlet of the water-cooled tubular cooler to the inlet of the gas analyzer via a pipeline, transporting the reduced-temperature and reduced-pressure working fluid to the gas analyzer 9 for gas composition analysis. The device utilizes the oxidation-carbonization mechanism when supercritical carbon dioxide reacts with metal pipelines to form an oxide film. When the oxide film on the pipeline surface peels off, the oxidation-carbonization reaction causes the carbon monoxide concentration to rise. By monitoring the change in carbon monoxide concentration, the extent of oxide film peeling inside the high-temperature pipeline can be determined.

[0011] The locations where oxide scale peeling is prone to occur are U-shaped bends and pipeline weld joints; multiple sets of monitoring devices are arranged, the monitoring results are compared with each other, and the oxide scale peeling locations are accurately located according to the changes in carbon monoxide concentrations at different sampling points.

[0012] The gas flow meter 10 monitors the flow of the working medium in real time and has the ability to control and regulate the flow.

[0013] The pressure reducing valve 11 is a piston-type gas pressure reducing valve, which can keep the output pressure stable within a certain range.

[0014] The cooler 7 is a water-cooled tubular heat exchanger.

[0015] The purpose of using the oxygenator 6 in the supercritical CO2 system is to add a trace amount of oxygen not exceeding 30ppm, without changing the working performance of the working fluid, so that the carbon generated during the operation of the supercritical CO2 system reacts with the oxygen, thereby playing a carbon fixation role, slowing down the thickening rate of the carbonized zone inside the pipeline, and thus slowing down the corrosion rate of the pipeline and extending the service life of the equipment.

[0016] The purpose of using the slag dryer 5 in the supercritical CO2 system is to reduce the amount of water vapor and oxide particles contained in the working fluid, while reducing the corrosion effect of water vapor on the pipeline and the wear degree of the pipeline by oxide particles, and avoiding the overheating and bursting of the pipeline caused by the accumulation of oxide particles.

[0017] The monitoring method of the supercritical CO2 circulating heated surface corrosion inhibition and oxide film peeling monitoring device comprises the following steps:

[0018] Step 1: Conduct preliminary experiments: Through preliminary experiments, obtain experimental data on the critical carbon monoxide concentration corresponding to the peeling of oxide scale under different pipe materials, working fluid temperatures, and working fluid pressures;

[0019] Step 2: Set monitoring points and take samples near the working medium inlet, the middle of the pipeline, and the working medium outlet of the high-temperature superheater 12, as well as locations where oxide film peeling is likely to occur. The working medium from the high-temperature superheater 12 is reduced in pressure through the pressure reducing valve 11.

[0020] Step 3: The cooler 7 cools the low-pressure and high-temperature working fluid passing through, and controls and monitors the flow rate of the working fluid through the gas flow meter 10 to prevent damage to the monitoring device due to excessive flow rate;

[0021] Step 4: After the gas analyzer 9 monitors and analyzes the gas component concentration of the low-temperature, low-pressure working fluid, it processes the monitoring results and transmits them to the computer host in real time, presenting a curve showing the change in the concentration of carbon monoxide, carbon dioxide, and oxygen over time on the host screen; at the same time, the computer host compares the real-time monitored carbon monoxide concentration data with the data obtained in the pre-experiment. Under the same working conditions, if the carbon monoxide concentration is higher than the pre-experimental threshold, an alarm is issued. If the carbon monoxide concentration shows an abnormal change trend, an alarm is issued.

[0022] Step 5: After monitoring, the working fluid is discharged after post-processing.

[0023] Compared with the existing technology, the present invention has the following advantages:

[0024] (1) The present invention utilizes the fact that the peeling of the oxide film will lead to an increase in the carbon monoxide concentration. It samples the working fluid at the high-temperature superheater and monitors it in real time. The monitoring data is compared and analyzed with the pre-experimental data. When the carbon monoxide concentration exceeds the critical concentration or the carbon monoxide concentration rises abnormally, the computer host issues an alarm, allowing the crew to promptly understand and determine the phenomenon of oxide peeling in the pipeline. Compared with the method of monitoring the working fluid temperature, the present invention makes a more accurate judgment;

[0025] (2) The present invention measures points at the front, middle, and rear of the high-temperature superheater and compares and analyzes the monitoring data to accurately locate the location where the oxide scale is flaking. For areas prone to oxide scale flaking, such as U-bends and pipe weld joints, monitoring equipment can be added as needed to monitor the hazardous area in real time, facilitating timely assessment of the oxide scale flaking situation in that area. Compared to conventional monitoring devices, the present invention is more accurate and reliable.

[0026] (3) The devices used in the present invention: pressure reducing valves, gas flow meters, and gas analyzers are mature and widely applicable to system modification and installation. The monitoring equipment is cheap and the monitoring cost is low. Multi-point online real-time synchronous monitoring is performed on areas prone to oxide scale flaking. When the computer host determines that oxide scale flaking may occur, an early warning is issued to the crew. In addition, this device is the simplest supercritical carbon dioxide cycle power generation system built based on the Brayton cycle, which is the basis for other complex cycle systems. Therefore, the present invention can be used in supercritical carbon dioxide systems with heat recovery, reheating, and other equipment at different pressures. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the installation and composition of the monitoring device of the present invention.

[0028] Figure 2 This is the corrosion interface diagram before peeling.

[0029] Figure 3a This is the size diagram of the inner and outer layers of the ferroferric oxide in the oxidation zone. Figure 3b This is a diagram showing the size of the iron-chromium oxide in the inner and outer layers of the oxidation zone. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0031] like Figure 1As shown, the present invention provides a monitoring device for corrosion inhibition and oxide film exfoliation on heating surfaces in a supercritical CO2 cycle, comprising a pressure reducing valve 11, a cooler 7, a gas flowmeter 10, and a gas analyzer 9. The working fluid absorbs low-temperature waste heat through a regenerator 3, then is raised to a higher operating temperature by a heat source 8 and a high-temperature superheater 12. After reaching a supercritical state, it enters a steam turbine 1 to perform turbine work, driving a generator 2. The low-pressure, high-temperature working fluid, having performed work, releases heat through a regenerator 3 and is then cooled by a cooler 7. The low-temperature, low-pressure working fluid passes through an oxygenator 6 and a deslagging dryer 5 before returning to the compressor 4 to increase its pressure, forming a supercritical CO2 system loop. The pressure reducing valve 11 is connected to the high-temperature superheater 12 to reduce the pressure of the sampled working fluid. The working fluid sampling locations on the high-temperature superheater pipeline can be adjusted according to monitoring needs, including near the pipeline inlet, the middle of the pipeline, near the pipeline outlet, and locations prone to oxide scale exfoliation, such as U-bends and pipeline weld joints. The depressurized monitored working fluid enters cooler 7 for cooling. A gas flowmeter 10, located between cooler 7 and gas analyzer 9, controls the working fluid flow rate while connecting the cooler outlet to the gas analyzer inlet via a pipeline, transporting the cooled and depressurized working fluid to the gas analyzer 9 for gas composition analysis. This utilizes the oxidation-carbonization mechanism when supercritical carbon dioxide reacts with metal pipes to form an oxide film. When the oxide film peels off from the pipe surface, the oxidation-carbonization reaction causes the carbon monoxide concentration to rise. By monitoring the change in carbon monoxide concentration, it is possible to determine whether the oxide film is peeling off inside the high-temperature pipe.

[0032] The pressure reducing valve 11 is a piston type gas pressure reducing valve, which can keep the output pressure stable within a certain range. In order to prevent the pressure after the valve from over-pressurizing, a pressure reducing valve should be installed at least four meters away from the valve outlet.

[0033] The cooler 7 is a water-cooled tubular heat exchanger, which cools the working medium after the regenerator and the sampled working medium.

[0034] The gas flow meter 10 monitors the flow of the working medium in real time and has a control capability to regulate the flow.

[0035] The purpose of using the oxygenator 6 in the supercritical CO2 system is to add a trace amount of oxygen not exceeding 30ppm, without changing the working performance of the working fluid, so that the carbon generated during the operation of the supercritical CO2 system reacts with the oxygen to play a carbon fixation role, thereby reducing the corrosion caused by carburization.

[0036] The purpose of the deslagging dryer 5 in the supercritical CO2 system is to reduce the amount of water vapor and oxide particles in the working fluid. Deslagging reduces the wear of the pipes by oxide particles and the possibility of overheating and bursting due to blockage by oxide particles. Drying the working fluid reduces the corrosive effects of water vapor on the pipes. The deslagging dryer consists of two parts. The front part first performs filtering and deslagging. The filters are arranged in a dual-path configuration. When the differential pressure of filter No. 1 increases to the alarm value, it is determined that the filter is clogged. Filter No. 2 is activated without shutting down the system, completing the online filter switching. The clogged filter No. 1 is then cleaned. The deslagging valve is opened, and the device reverses the air flow to backflush the filter. The filter is also micro-vibrated to enhance its cleaning function. After a certain period of backflush, the deslagging valve is closed, and filter No. 1 returns to standby mode. The rear part of the device dries the working fluid. Its operating principle is based on the attractiveness of activated alumina to water molecules. When the working fluid passes through the device, the activated alumina absorbs the water vapor in the working fluid without reacting with the working fluid. When the moisture reaches saturation, the bound moisture in the desiccant is removed by heating, restoring its moisture absorption capacity. The performance and efficiency are not affected by repeated heating and regeneration.

[0037] The monitoring method of the supercritical CO2 circulating heated surface corrosion inhibition and oxide film peeling monitoring device comprises the following steps:

[0038] Step 1: Conduct preliminary experiments: Through preliminary experiments, obtain experimental data on the critical carbon monoxide concentration corresponding to the peeling of oxide scale under different pipe materials, working fluid temperatures, and working fluid pressures;

[0039] Step 2: Set monitoring points and take samples at three points: near the working medium inlet, in the middle of the pipeline, and near the working medium outlet of the high-temperature superheater 12. The working medium from the high-temperature superheater 12 is reduced in pressure through the piston-type gas pressure reducing valve 11.

[0040] Step 3: The cooler 7 cools the low-pressure and high-temperature working fluid passing through, and controls and monitors the flow rate of the working fluid through the gas flow meter 10 to prevent damage to the monitoring device due to excessive flow rate;

[0041] Step 4: After the gas analyzer 9 monitors and analyzes the gas component concentration of the low-temperature, low-pressure working fluid, it processes the monitoring results and transmits them to the host computer in real time, displaying the time-varying curves of the carbon monoxide, carbon dioxide, and oxygen concentrations on the host screen. At the same time, the host computer compares the real-time monitored carbon monoxide concentration data with the data obtained from the pre-experimental test. Under the same working conditions, if the carbon monoxide concentration exceeds the pre-experimental threshold, an alarm is issued; if the carbon monoxide concentration shows an abnormal trend, an alarm is issued.

[0042] Step 5: After monitoring, the working fluid is discharged after post-processing.

[0043] The working fluid parameters after cooling and pressure reduction should not exceed the operating temperature, working pressure and flow control range of the piston gas pressure reducing valve 11, cooler 7, gas flow meter 10 and gas analyzer 9, so as to avoid damaging the monitoring device and reducing the equipment's monitoring accuracy of carbon monoxide concentration.

[0044] The working fluid is primarily carbon dioxide, with small amounts of carbon monoxide and oxygen. The material of the monitoring device should not react with the working fluid to avoid affecting the monitoring results. The airtightness of the device should also be monitored to prevent leakage of the working fluid.

[0045] The sampling points can be adjusted in position according to the monitoring needs of the work. More monitoring equipment can be arranged at the U-shaped bends and pipeline weld joints to accurately locate the location of oxide scale peeling.

[0046] The preliminary experiment was conducted to obtain experimental data on the critical carbon monoxide concentration corresponding to the occurrence of cracking and flaking of the oxide scale under different conditions of pipeline materials, working fluid temperature, and working fluid pressure. This data was used as the basis for judging whether the oxide scale on the pipeline surface was flaking and as a reference during actual monitoring. Among them, the pipeline materials used in the preliminary experiment were TP316L, TP347HFG, TP347H, SUPER304H, and T91, five high-temperature alloys with high strength, good corrosion resistance, and stable structure. The working fluid temperature range was 400-1000℃, and one group of experiments was conducted every 50℃, for a total of 13 groups. The working fluid pressure range was 0.1-30MPa, and one group of experiments was conducted every 3MPa, for a total of 11 groups. Under the condition that other parameters remained unchanged, a single-factor preliminary experiment was carried out by changing a certain variable to obtain the carbon monoxide concentration when the oxide scale was flaking under these working conditions.

[0047] The principles of the present invention are as follows:

[0048] Before the oxide scale peeling occurs, the corrosion layer on the pipe surface is as follows: Figure 2 As shown:

[0049] Among them, the sizes of ferroferric oxide and ferrochromium oxide are very different, such as Figure 3a and Figure 3b shown.

[0050] When a supercritical CO2 system is operating smoothly, its surface oxide scale exhibits four layers: ferroferric oxide, iron-chromium oxide, a carbonized zone, and the pipe matrix. Previous studies have shown that due to the significant size difference between ferroferric oxide and iron-chromium oxide, iron-chromium oxide provides more carbon atom adsorption and reaction sites, leading to carbon deposition. The carbonized zone forms because the radius of carbon ions is smaller than that of oxygen ions, making it easier for them to diffuse into the pipe matrix through gaps or vacancies and form carbides with metallic elements such as Fe and Cr. As the supercritical CO2 system operates, the thickness of the carbonized zone gradually increases. A thicker carbonized zone weakens the bond between the oxide scale and the pipe matrix, making it more susceptible to cracking and flaking.

[0051] In this case, thermal stress and other factors cause the oxide scale to flake off, resulting in direct contact between the iron-chromium oxide and supercritical carbon dioxide. Consequently, a new ferroferric oxide film is regenerated on the pipe surface to protect the substrate. During this process, due to the oxidation-carbonization effect of supercritical carbon dioxide, the metal substrate reacts not only with oxygen but also with carbon dioxide. The equation is as follows:

[0052] 3Fe+4CO2=Fe3O4+4CO

[0053] 6Fe+4CO2=2Fe3O4+4C

[0054] 3Fe+4CO=Fe3O4+4C

[0055] As can be seen from the equation, the iron element in the pipeline matrix continuously reacts with carbon dioxide to produce ferroferric oxide, carbon monoxide, and carbon. Due to the smaller radius of carbon ions, they are more likely to diffuse into the interior of the pipeline matrix and react with iron and chromium elements to form carbides, increasing the thickness of the carbonized zone and the depth of carbonization. At this time, the carbon generated during the scale regeneration process reacts with carbon dioxide to continuously generate carbon monoxide, causing the carbon monoxide concentration to continuously increase. Therefore, by monitoring and analyzing the changes in the carbon monoxide concentration in the working fluid, the peeling of the scale can be reflected. The reaction equation of carbon and carbon dioxide is as follows:

[0056] C+CO2=2CO.

Claims

1. A supercritical CO2 circulating heating surface corrosion inhibition and oxide film peeling monitoring device, characterized by: The monitoring device comprises a sampling pipe connected to the vicinity of the pipe inlet, the middle of the pipe, the vicinity of the pipe outlet and the position where the oxide film is likely to peel off of the supercritical CO2 system, and a pressure reducing valve (11), a cooler (7), a gas flow meter (10) and a gas analyzer (9) arranged in sequence on the sampling pipe; the pressure reducing valve (11) performs pressure reduction treatment on the sampled working medium, and the sampled working medium after pressure reduction enters the cooler (7) for cooling treatment; the gas flow meter (10) arranged between the cooler (7) and the gas analyzer (9) controls the flow rate of the working medium and connects the outlet of the water-cooled tubular cooler and the inlet of the gas analyzer through a pipe, so as to transport the working medium after temperature reduction and pressure reduction to the gas analyzer (9) for gas composition analysis; the oxidation-carbonization mechanism when supercritical carbon dioxide reacts with the metal pipe to form an oxide film is utilized, and when the oxide film on the pipe surface peels off, the oxidation-carbonization reaction causes the carbon monoxide concentration to rise, and by monitoring the change in carbon monoxide concentration, the peeling of the oxide film inside the high-temperature pipe can be judged; The monitoring method of the supercritical CO2 circulating heated surface corrosion inhibition and oxide film peeling monitoring device comprises the following steps: Step 1: Conduct preliminary experiments: Through preliminary experiments, obtain experimental data on the critical carbon monoxide concentration corresponding to the peeling of the oxide film under different pipe materials, working fluid temperatures, and working fluid pressures; Step 2: Monitoring points are set up near the working medium inlet of the high-temperature superheater (12) pipeline, in the middle of the pipeline, near the working medium outlet, and at locations where oxide film peeling is likely to occur, and samples are taken. The working medium from the high-temperature superheater (12) is reduced in pressure through the pressure reducing valve (11); Step 3: The cooler (7) cools the low-pressure and high-temperature working medium passing through, and controls and monitors the flow rate of the working medium through the gas flow meter (10) to prevent damage to the monitoring device due to excessive flow rate; Step 4: After the gas analyzer (9) monitors and analyzes the gas component concentration of the low-temperature and low-pressure working fluid, the monitoring results are processed and transmitted to the computer host in real time, and the concentration change curves of carbon monoxide, carbon dioxide and oxygen over time are displayed on the host screen; at the same time, the computer host compares the real-time monitored carbon monoxide concentration data with the data obtained in the pre-experiment. Under the same working conditions, if the carbon monoxide concentration is higher than the pre-experimental threshold, an alarm is issued. If the carbon monoxide concentration shows an abnormal change trend, an alarm is issued; Step 5: After monitoring, the working fluid is discharged after post-processing.

2. The device for monitoring corrosion inhibition and oxide film peeling of a supercritical CO2 circulating heating surface according to claim 1, characterized in that: The locations where oxide film peeling is prone to occur are U-shaped bends and pipeline weld joints; multiple sets of monitoring devices are arranged, the monitoring results are compared with each other, and the locations of oxide film peeling are accurately located according to the changes in carbon monoxide concentration at different sampling points.

3. The device for monitoring corrosion inhibition and oxide film peeling of a supercritical CO2 circulating heating surface according to claim 1, characterized in that: The gas flow meter (10) monitors the flow of the working medium in real time and has a control capability to regulate the flow.

4. The device for monitoring corrosion inhibition and oxide film peeling of a supercritical CO2 circulating heating surface according to claim 1, characterized in that: The pressure reducing valve (11) is a piston-type gas pressure reducing valve capable of keeping the output pressure stable within a certain range.

5. The device for monitoring corrosion inhibition and oxide film peeling of a supercritical CO2 circulating heating surface according to claim 1, characterized in that: The cooler (7) is a water-cooled tubular heat exchanger.

6. The device for monitoring corrosion inhibition and oxide film peeling of a supercritical CO2 circulating heating surface according to claim 1, characterized in that: An oxygenator (6) is provided between a compressor (4) and a first cooler (7-1) in a supercritical CO2 system. The oxygenator (6) is used to add a trace amount of oxygen not exceeding 30 ppm, so that carbon generated during the operation of the supercritical CO2 system reacts with oxygen without changing the working performance of the working medium, thereby playing a carbon fixation role, slowing down the thickening speed of the carbonized zone inside the pipeline, thereby slowing down the corrosion speed of the pipeline and extending the service life of the equipment.

7. The device for monitoring corrosion inhibition and oxide film peeling of a supercritical CO2 circulating heating surface according to claim 1, characterized in that: A slag removal dryer (5) is provided between a compressor (4) and a first cooler (7-1) in a supercritical CO2 system. The purpose of the slag removal dryer (5) is to reduce the amount of water vapor and oxide particles contained in the working medium, thereby reducing the corrosion effect of water vapor on the pipeline and the degree of wear of the pipeline by the oxide particles, and avoiding the phenomenon of overheating and bursting of the pipeline caused by the accumulation of oxide particles.

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