An on-line monitoring simulation device and method for flexible peak-shaving heated surface corrosion based on resistance method

Abstract

The application discloses a flexible peak-shaving heated surface corrosion online monitoring simulation device and method based on a resistance method, and belongs to the technical field of high-temperature corrosion online monitoring and experimental simulation. The device comprises a program temperature control module, a corrosion measurement module, a central synchronous control module, a pipeline heating module and a tail gas treatment module. The application can flexibly set a working condition program according to different units and operation modes, and overcomes the deficiency of traditional devices that are difficult to reflect actual peak-shaving transient characteristics under constant temperature and constant composition conditions. The application realizes in-situ online monitoring of the corrosion rate of the heated surface material under the flexible peak-shaving working condition, and makes up for the deficiency of the existing resistance method that is difficult to be directly used for such working conditions. In the same set of experimental devices, comprehensive working conditions close to actual operation can be simulated, and temperature factors and atmosphere factors can be separately studied, which is beneficial to quantitatively distinguishing the influence of each corrosion factor and coupling effect on the corrosion mechanism and corrosion rate.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature corrosion online monitoring and experimental simulation technology, specifically relating to a flexible peak-shaving heated surface corrosion online monitoring simulation device and method based on the resistance method. Background Technology

[0002] As the proportion of renewable energy in the power grid continues to increase, the tasks of deep peak shaving and frequent start-up and shutdown undertaken by thermal power units have increased significantly. During the flexible peak shaving process, the boiler heating surface not only experiences a large and rapid change in temperature field, but is also in an atmosphere field in which oxygen content, acidic / reducing components, sulfur-containing / chlorine-containing components fluctuate drastically over time, forming a complex thermo-chemical coupled corrosion environment.

[0003] Existing high-temperature corrosion studies are mostly conducted under steady-state temperatures and constant atmospheres, which makes it difficult to reflect transient corrosion behavior when temperature and atmospheric composition change rapidly and synchronously under flexible peak-shaving conditions. Commonly used offline testing methods such as gravimetric methods can only obtain the periodic average corrosion amount and cannot capture the instantaneous corrosion rate changes during rapid load increases and decreases. At the same time, existing experimental setups often only provide the combined effect of "temperature and atmosphere changing together", making it difficult to achieve controllable coupling and decoupling studies of temperature and atmosphere factors on the same platform. As a result, it is difficult to quantitatively distinguish the influence of each corrosion factor and its coupling effect on the corrosion mechanism and corrosion rate of the heated surface.

[0004] Therefore, it is necessary to provide a novel device and method that can programmatically simulate the transient temperature curves and dynamic changes in flue gas composition under flexible peak-shaving conditions in the laboratory; realize in-situ online measurement of corrosion behavior of heated surface materials; and flexibly switch between "temperature-atmosphere coupling conditions" and "temperature decoupling conditions" and "atmosphere decoupling conditions" in the same device to systematically carry out the coupling and decoupling research of corrosion factors. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, the technical problem to be solved by the present invention is to provide a flexible peak-shaving online monitoring simulation device and method for corrosion of heated surfaces based on the resistance method, which can be implemented under laboratory conditions:

[0006] (1) To flexibly reproduce the typical temperature transients and dynamic changes in flue gas composition experienced by the heating surface during the flexible peak-shaving process;

[0007] (2) The corrosion thickness change and instantaneous corrosion rate of the heated surface material were monitored in situ online using the resistance method;

[0008] (3) By simultaneously programmable temperature program and gas distribution program, the coupled working condition simulation of temperature field and atmosphere field and the decoupled working condition simulation of temperature or atmosphere factors can be realized, so as to quantitatively study the influence of different corrosion factors and their coupling effect on corrosion mechanism and corrosion rate.

[0009] Technical Solution: To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] A flexible peak-shaving heated surface corrosion online monitoring simulation device based on resistance method, comprising:

[0011] The programmable temperature control module is used to provide the test space and to heat or cool the test space.

[0012] The corrosion measurement module includes a real-time corrosion measurement unit and a weight loss test unit set in the program temperature control module. The real-time corrosion measurement unit is used to measure the corrosion behavior of the boiler heating surface material under simulated working conditions online, and the weight loss test unit is used to verify the corrosion behavior of the boiler heating surface material under simulated working conditions offline.

[0013] A dynamic gas distribution module is used to provide the programmed temperature control module with a corrosive atmosphere whose composition and flow rate vary over time.

[0014] The central synchronization control module is used to synchronously control the temperature of the program temperature control module and the gas distribution of the dynamic gas distribution module based on a unified time reference.

[0015] The pipeline heating module is used to heat and insulate the gas pipeline between the dynamic gas distribution module and the program temperature control module.

[0016] The exhaust gas treatment module is used to purify the experimental exhaust gas discharged from the program temperature control module.

[0017] Preferably, the programmed temperature control module is a tubular furnace, the real-time corrosion measurement unit is a test resistor, the test resistor includes a bending section, the test resistor is made of the same material as the boiler heating surface material, the weight loss test unit includes multiple metal samples for calculating the average corrosion thickness based on mass loss, the metal samples are made of the same material as the boiler heating surface material, the dynamic gas distribution module includes multiple gas supply units, a mass flow controller, and a premixed heating unit, the multiple gas supply units are used to provide two or more gases including nitrogen, oxygen, carbon dioxide, sulfur dioxide, carbon monoxide, water vapor, and hydrogen chloride, the mass flow controller is connected to the multiple... A gas supply unit is connected to regulate the flow rate of each gas. A premixed heating unit is connected to a mass flow controller to mix and heat two or more gases. The mixed gas, heated to a predetermined temperature, is sent to a programmable temperature control module. The central synchronous control module is used to send temperature programs to the programmable temperature control module and gas distribution programs to the dynamic gas distribution module. The temperature programs and gas distribution programs are configured as follows: a coupled operating condition in which temperature and atmospheric composition change synchronously over time; a temperature decoupling operating condition in which temperature changes over time while atmospheric composition remains constant; and an atmosphere decoupling operating condition in which atmospheric composition changes over time while temperature remains constant. This is to achieve the coupling and decoupling simulation of important corrosion factors under flexible peak-shaving conditions.

[0018] Preferably, the temperature control module has a temperature range of 25℃ to 1200℃ and a heating or cooling rate of not less than 15℃ / min.

[0019] Preferably, it also includes a temperature compensation measurement unit for establishing a resistance-temperature calibration relationship in a non-corrosive environment. The temperature compensation measurement unit includes an inert gas supply unit connected to both the program temperature control module and the central synchronization control module, and a temperature compensation resistor connected to the central synchronization control module. The temperature compensation resistor has the same structure and material as the test resistor, and the temperature compensation resistor is located inside the program temperature control module when it is in operation.

[0020] Preferably, the central synchronous control module includes a potentiostat connected to the corrosion measurement module and a computer connected to the potentiostat. The potentiostat applies a constant voltage to the test resistor and measures the resistance value of the test resistor at preset time intervals. The corrosion thickness and average corrosion rate of the test resistor are calculated by the change in the resistance value of the test resistor.

[0021] Preferably, the pipeline heating module heats the gas supply pipeline between the dynamic gas distribution module and the program temperature control module to above 150°C.

[0022] A simulation method for online monitoring of corrosion on flexible peak-shaving heated surfaces based on resistance method, using the aforementioned online monitoring simulation device for corrosion on flexible peak-shaving heated surfaces based on resistance method, includes the following steps:

[0023] S1. Install a real-time corrosion measurement unit in the furnace cavity of the program temperature control module, and arrange the metal sample of the weight loss test unit. The real-time corrosion measurement unit is connected to the central synchronous control module through wires.

[0024] S2. Set the temperature program and gas distribution program in the central synchronous control module. According to the experimental purpose, configure the two as a coupled program where the temperature and atmosphere change synchronously, a temperature decoupling program where the temperature changes while the atmosphere remains constant, or an atmosphere decoupling program where the atmosphere changes while the temperature remains constant, and send them to the program temperature control module and the dynamic gas distribution module respectively.

[0025] S3. The program temperature control module changes the furnace temperature according to the temperature program. At the same time, the dynamic gas distribution module adjusts the flow rate of each gas in various gases according to the gas distribution program. After being mixed and heated by the premixed heating unit, the gas is sent into the furnace, so that the corrosion real-time measurement unit is under the target coupling or decoupling corrosion conditions.

[0026] S4. The potentiostat performs resistance measurements on the corrosion real-time measurement unit at preset time intervals, and the computer records the real-time data of resistance changes over time.

[0027] S5. The resistance data of the real-time corrosion measurement unit is temperature compensated using the resistance-temperature calibration relationship. The cross-sectional area change and corrosion thickness change of the test resistance at each measurement time point are calculated, and the average corrosion rate within the corresponding time period is obtained, so as to realize the in-situ online monitoring of the corrosion behavior of the real-time corrosion measurement unit.

[0028] S6. Weigh the metal sample in the weight loss test unit, calculate the average corrosion thickness during the experimental period, and compare it with the online measurement results obtained in step S5.

[0029] Preferably, the resistance-temperature calibration relationship in step S5 is obtained through a temperature compensation measurement unit, and the process includes the following steps:

[0030] S101. Before step S1, place the temperature compensation resistor inside the furnace cavity of the program temperature control module. The temperature compensation resistor is connected to the central synchronous control module through a wire.

[0031] S102, the program temperature control module heats up, and the inert gas supply unit supplies inert gas into the furnace cavity of the program temperature control module;

[0032] S103. The potentiostat of the central synchronous control module measures the resistance value of the temperature compensation resistor at preset time intervals to establish the resistance-temperature calibration relationship under non-corrosive conditions.

[0033] Preferably, the metal sample in the weight loss test unit is characterized and analyzed, including: observing the surface and cross-sectional morphology of the corrosion products using a scanning electron microscope; analyzing the elemental distribution of the corrosion products using an energy dispersive spectroscopy (EDS) instrument; and analyzing the phase composition of the corrosion products using an X-ray diffractometer.

[0034] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0035] 1. Specialized simulation capability for flexible peak-shaving conditions: Through a programmable high-temperature tubular furnace and a dynamic gas distribution module, this invention can reproduce, under laboratory conditions, typical rapid load increase and decrease temperature curves during boiler flexible peak-shaving, as well as the dynamic changes in flue gas components such as oxygen, carbon dioxide, sulfur dioxide, carbon monoxide, hydrogen chloride, and water vapor. The operating condition program can be flexibly set according to different units and operating modes, overcoming the shortcomings of traditional devices that mostly conduct corrosion tests under constant temperature and constant composition conditions and are difficult to reflect the transient characteristics of actual peak-shaving conditions.

[0036] 2. Resistance method online monitoring structure suitable for high-temperature dynamic corrosion environment: This invention uses a test resistor with the same material as the boiler heating surface and sets up a temperature compensation resistor with the same structure and wiring method, placed in an inert atmosphere. The resistance-temperature calibration relationship is established by using the temperature compensation resistor. The resistance data of the test resistor under drastic temperature changes and complex corrosive atmosphere is temperature compensated, so that the resistance change corresponds reliably with the cross-sectional area change and corrosion thickness change. This enables in-situ online monitoring of the corrosion rate of the heating surface material under flexible peak-shaving conditions, making up for the shortcomings of the existing resistance method, which is mostly applied to relatively stable environments and is difficult to apply directly to such conditions.

[0037] 3. Achieving Coupling and Decoupling Studies of Corrosion Factors on a Single Platform: This invention features a central synchronous control module that allows for programmable control of both the temperature and gas distribution programs. It can be configured as needed to achieve coupled operating conditions with synchronized changes in temperature and atmospheric composition, as well as decoupled operating conditions with either temperature variation / constant atmosphere or vice versa. Within a single experimental setup, it can simulate near-real-world operating conditions while simultaneously enabling separate studies of temperature and atmospheric factors. This facilitates the quantitative differentiation of the impacts of various corrosion factors and their coupling effects on corrosion mechanisms and rates. Existing technologies generally lack such a switchable, unified platform.

[0038] 4. Comparison of online resistance data with offline weight loss data improves quantitative reliability: Based on online monitoring using the resistance method, this invention sets up parallel metal samples for weight loss testing. By comparing the average corrosion thickness under the same working conditions with the changes in corrosion thickness measured online, and comparing it with the resistance method measurement, the quantitative accuracy and comparability of the online monitoring data are improved.

[0039] 5. Supporting mechanism analysis with microscopic and phase characterization: This invention combines characterization methods such as scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction to analyze the characteristics of corrosion products under different coupling / decoupling conditions from multiple perspectives, including morphology, elemental distribution, and phase composition. This provides a systematic experimental platform and data support for revealing the high-temperature corrosion mechanism of heated surfaces under flexible peak-shaving conditions, which is beneficial for the establishment of subsequent protection measures and life assessment methods. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the overall structure of the device according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the test resistor structure for an example embodiment;

[0042] Figure 3 This is a schematic diagram of the connection structure of the temperature compensation resistor measurement unit in the embodiment.

[0043] Figure 4 This is a schematic diagram of the operating condition control and testing process of the device of the present invention. Detailed Implementation

[0044] The present invention will be further illustrated below with reference to specific embodiments. These embodiments are implemented based on the technical solutions of the present invention, and it should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0045] Example 1

[0046] like Figure 1 As shown, a flexible peak-shaving heated surface corrosion online monitoring simulation device based on the resistance method includes:

[0047] The programmable temperature control module 1 is used to provide the test space and heat or cool it. This module is a tube furnace; in this embodiment, an existing programmable high-temperature tube furnace, such as the JKR-WGXL tube furnace from Jinkairui Furnace Industry, is used. By setting a heating / cooling program, the furnace temperature is precisely controlled over time to reproduce typical temperature processes such as rapid load increase, rapid load decrease, and start-up / shutdown during flexible peak shaving. The programmable temperature control module 1 has a heating / cooling range of 25℃ to 1200℃, and a heating or cooling rate of no less than 15℃ / min.

[0048] The corrosion measurement module 2 includes a real-time corrosion measurement unit and a weight loss test unit installed within the program temperature control module 1. The real-time corrosion measurement unit is used to measure the corrosion behavior of the boiler heating surface material under simulated operating conditions online, while the weight loss test unit is used to verify the corrosion behavior of the boiler heating surface material under simulated operating conditions offline. The real-time corrosion measurement unit is a test resistor, which includes multiple bends forming a serpentine resistance element. The test resistor is made of the same metal wire or strip as the boiler heating surface material, and its resistance value is increased through multiple bends (or winding). Figure 2 As shown in the diagram, this embodiment uses TP347H stainless steel as the resistance material, and it is led out to the outside of the furnace via a wire (nickel wire in this embodiment) and connected to the potentiostat of the central synchronous control module 3. The potentiostat applies a constant voltage to the test resistor, collects the current signal, and calculates the resistance value. The weight loss test unit consists of multiple parallel metal samples. The average corrosion thickness is calculated through mass loss to verify the online measurement results of the resistance method. The metal samples are made of the same material as the boiler heating surface material (TP347H stainless steel). Basic mechanism: The resistance value of the test resistor is related to its geometric dimensions and material resistivity. Corrosion leads to a reduction in effective cross-sectional area or a change in resistivity, which is reflected as a change in resistance over time. By establishing the relationship between geometric / material parameters and resistance changes, the corrosion thickness and corrosion rate changes over time can be calculated.

[0049] The dynamic gas distribution module 4 is used to provide a corrosive atmosphere with varying composition and flow rate over time to the programmable temperature control module 1. The dynamic gas distribution module 4 includes multiple gas supply units, a mass flow controller, and a premixed heating unit. The multiple gas supply units provide two or more gases selected from nitrogen, oxygen, carbon dioxide, sulfur dioxide, carbon monoxide, water vapor, and hydrogen chloride. Nitrogen, oxygen, carbon dioxide, sulfur dioxide, carbon monoxide, and hydrogen chloride are supplied via gas cylinders, while water vapor is supplied via a steam generator. The mass flow controller is connected to the multiple gas supply units, and the precise flow rate of each gas over time is achieved through the gas distribution program issued by the central synchronous control module 3. For precise adjustment, the mass flow controller in this embodiment uses the Beijing Precision ACU10FD-LC mass flow meter to realize the time-series proportioning, switching and steady-state output of multiple gases (including corrosive components / inert gases, etc.). It accepts the flow / proportioning program and outputs the target atmosphere to the reaction zone. The atmosphere variable in the "coupling / decoupling condition" is formed through flow control and switching strategy. The premixed heating unit is connected to the mass flow controller and is used to mix and heat two or more gases. The premixed heating unit is connected to the program temperature control module 1 through the pipeline. The mixed gas heated to the predetermined temperature is sent into the furnace cavity of the program temperature control module 1 to construct a programmable corrosive atmosphere field.

[0050] The central synchronous control module 3 is used to synchronously control the temperature of the program temperature control module 1 and the gas distribution of the dynamic gas distribution module 4 based on a unified time reference. The central synchronous control module 3 includes a potentiostat connected to the corrosion measurement module 2 and a computer connected to the potentiostat. The potentiostat (e.g., Merrick RK2517-4) applies a constant voltage to the test resistor and measures the resistance value of the test resistor at preset time intervals. The corrosion thickness and short-term average corrosion rate of the test resistor are calculated based on the change in the resistance value. The computer in the central synchronous control module 3 sends temperature programs to the program temperature control module 1 and gas distribution programs to the dynamic gas distribution module 4. The temperature and gas distribution programs are configured for the following three operating conditions: a coupled operating condition where temperature and atmospheric composition change synchronously over time; a temperature decoupling operating condition where temperature changes over time but atmospheric composition remains constant; and an atmospheric decoupling operating condition where atmospheric composition changes over time but temperature remains constant. This allows for the simulation of coupling and decoupling of important corrosion factors under flexible peak-shaving conditions.

[0051] The pipeline heating module 5 is used to heat and insulate the gas pipeline between the dynamic gas distribution module 4 and the program temperature control module 1. The gas pipeline is heated to above 150°C to prevent water vapor and acidic components from condensing. In this embodiment, the pipeline heating module 5 uses an electric heating tape and an intelligent temperature control device. The electric heating tape is wrapped around the gas pipeline. The electric heating tape uses existing constant power electric heating tape (such as glass fiber heating tape). The intelligent temperature control device is connected to the electric heating tape to control the temperature of the electric heating tape. The intelligent temperature control device uses an existing temperature controller, such as the Yunjing Technology YJ-DI956 digital temperature controller.

[0052] The exhaust gas treatment module 6 is used to purify the experimental exhaust gas discharged from the program temperature control module 1, and to absorb or catalytically oxidize the corrosive exhaust gas containing sulfur, carbon and halogen. The exhaust gas treatment module 6 adopts the existing alkaline absorption device and activated carbon adsorption device to ensure that the emissions meet environmental protection requirements.

[0053] like Figure 3As shown, the flexible peak-shaving heated surface corrosion online monitoring simulation device based on the resistance method in this embodiment also includes a temperature compensation measurement unit, used to establish a resistance-temperature calibration relationship in a non-corrosive environment. The temperature compensation measurement unit includes an inert gas supply unit and a temperature compensation resistor. The inert gas supply unit is connected to both the program temperature control module 1 and the central synchronous control module 3. The inert gas supply unit includes an inert gas cylinder and an inert gas control valve. The inert gas cylinder stores inert gases such as argon. The inert gas control valve is connected to the computer of the central synchronous control module 3, and the computer controls the opening and closing of the inert gas control valve. The temperature compensation resistor is connected to the central synchronous control module 3 through a wire. The temperature compensation resistor and the test resistor have the same structure. The materials are identical. During operation, the temperature compensation resistor is located inside the furnace cavity of the programmable temperature control module 1. An inert gas supply unit provides inert gas to the furnace cavity, ensuring the temperature compensation resistor operates in a non-corrosive environment. The temperature compensation resistor reflects the effect of temperature changes on resistance in real time, used for temperature correction of the test resistor measurement results. (The temperature compensation resistor is completely identical to the test resistor; only the experimental environment differs. By placing the temperature compensation resistor in a programmable tube furnace with the same temperature setting as the test resistor's tube furnace and introducing inert gas, it is ensured that the temperature compensation resistor does not participate in the corrosion process, but its temperature is the same as the test resistor. At this time, the resistance value of the temperature compensation resistor is the resistance R0 of the test resistor at temperature T without corrosion.)

[0054] This embodiment also provides a simulation method for online monitoring of corrosion of flexible peak-shaving heated surfaces based on the resistance method. Using the aforementioned online monitoring simulation device for corrosion of flexible peak-shaving heated surfaces based on the resistance method, the method includes the following steps:

[0055] S1. Install a corrosion real-time measurement unit (test resistor) in the furnace cavity of the program temperature control module 1, and arrange the metal sample of the weight loss test unit. The test resistor is connected to the central synchronous control module 3 through a wire.

[0056] S2. Set the temperature program and gas distribution program in the central synchronous control module 3. According to the experimental purpose, configure the two as a coupled program where the temperature and atmosphere change synchronously, a temperature decoupling program where the temperature changes while the atmosphere remains constant, or an atmosphere decoupling program where the atmosphere changes while the temperature remains constant, and send them to the program temperature control module 1 and the dynamic gas distribution module 4 respectively.

[0057] S3. The program temperature control module 1 changes the furnace cavity temperature according to the temperature program. At the same time, the dynamic gas distribution module 4 adjusts the flow rate of each gas in the various gases according to the gas distribution program. After being mixed and heated by the premixed heating unit, the gas is sent into the furnace cavity. The pipeline heating module 5 works synchronously to heat the gas pipeline, so that the test resistance is under the target coupling or decoupling corrosion condition.

[0058] like Figure 3As shown, in this embodiment, based on the actual boiler heating surface operating under flexible peak-shaving conditions, the corresponding temperature and atmosphere data of the boiler heating surface are obtained, and the dynamic changes of temperature and atmosphere in the program temperature control module 1 are set according to this data. The flow-time curves of each gas are preset in the central synchronous control module 3.

[0059] When simulating coupled operating conditions, the temperature program and the gas flow programs are set synchronously on the same time axis. For example, during the rapid load reduction process, the furnace temperature drops from high temperature (750℃) to medium temperature (450℃), the O2 concentration decreases and the CO / SO2 concentration increases, so as to reproduce the actual peak-shaving environment.

[0060] When simulating temperature decoupling conditions, the temperature program is changed in the central synchronous control module 3 to keep the gas distribution program constant, so as to examine the effect of temperature transients on corrosion.

[0061] When simulating decoupled atmospheric conditions, the temperature program is kept constant, and only the gas flow programs are changed to study the effects of individual or combined changes in oxygen content, acidic gases, reducing components, etc., on corrosion behavior.

[0062] S4. The potentiostat measures the resistance of the test resistor at preset time intervals and records the resistance change data over time in real time.

[0063] In this embodiment, the resistance measurement is performed automatically at set time intervals during the experiment. A constant voltage is applied to the test resistor by a potentiostat, and the instantaneous resistance value of the test resistor is calculated by measuring the current. The computer synchronously records the furnace cavity temperature of the program temperature control module 1, the atmosphere composition output by the dynamic gas distribution module 4, and the data on the change of the resistance value of the test resistor over time.

[0064] S5. The resistance data of the test resistor is temperature compensated by the resistance-temperature calibration relationship. The cross-sectional area change and corrosion thickness change of the test resistor at each measurement time point are calculated, and the short-term average corrosion rate in the corresponding time period is obtained, so as to realize the in-situ online monitoring of the corrosion behavior of the heated surface material.

[0065] The test resistor has an area of ​​S, a thickness of d, and a length of l. Its resistivity is ρ (resistivity depends only on temperature and material). The temperature compensation resistor value at temperature T is R0 (obtained from the temperature compensation resistor). The resistance of the test resistor is R. Since the test resistor and the temperature compensation resistor are identical in material, temperature, and size, differing only in thickness due to corrosion, the resistivity formula is used to determine the resistance.

[0066]

[0067] We can obtain,

[0068]

[0069] In the formula, l0 is the length of the temperature compensation resistor, which is equal to the length l of the test resistor, S0 is the area of ​​the temperature compensation resistor, and d0 is the thickness of the temperature compensation resistor.

[0070] R and R0 can be measured by a potentiostat, therefore d, the change in corrosion thickness, can be calculated:

[0071]

[0072] S6. After the resistance method measurement is completed, the metal sample in the weight loss test unit is weighed, the average corrosion thickness during the experimental period is calculated, and it is compared with the online measurement results obtained in step S5 for verification of the accuracy of the resistance method measurement.

[0073] After completing the mass loss calculation, the metal samples in the weight loss test unit were characterized and analyzed, including: using scanning electron microscopy (SEM) to observe the surface and cross-sectional morphology of the corrosion products; using energy dispersive spectroscopy (EDS) to analyze the elemental distribution of the corrosion products; and using X-ray diffraction (XRD) to analyze the phase composition of the corrosion products, so as to reveal the differences in corrosion mechanisms under different coupling or decoupling conditions.

[0074] In this embodiment, the resistance-temperature calibration relationship is obtained through a temperature compensation measurement unit before step S1. The process includes the following steps:

[0075] S101. Before step S1, place the temperature compensation resistor inside the furnace cavity of the program temperature control module 1. The temperature compensation resistor is connected to the central synchronous control module 3 through a wire.

[0076] S102, the program temperature control module 1 heats up, and the inert gas supply unit supplies inert gas into the furnace cavity of the program temperature control module 1.

[0077] S103, the potentiostat of the central synchronous control module 3 measures the resistance value of the temperature compensation resistor at preset time intervals to establish the resistance-temperature calibration relationship under non-corrosive environment.

[0078] After obtaining the resistance-temperature calibration relationship, the temperature compensation resistor is removed from the furnace cavity of the program temperature control module 1.

[0079] Example 2

[0080] This embodiment takes a pulverized coal boiler participating in flexible peak shaving as an example. Its water-cooled wall material is 15CrMoG, and the test resistance can be made of 15CrMoG material. Figure 2The shape shown indicates the geometric parameters of the tested resistor, such as: 2mm thick, 5mm wide; the serpentine bending structure has each segment 50mm long, segment spacing 5mm, and a total unfolded length of 325mm. Nickel wire is soldered to both ends of the resistor sheet.

[0081] 1. Tubular furnace temperature program setting (one cycle is 24 hours, and it runs continuously 7 times).

[0082] The temperature cycle range of the tubular furnace is set to 450℃-750℃, and each cycle includes:

[0083] Phase T1 (rapid load increase and temperature rise): 450℃ to 750℃ at a rate of 15℃ / min (approximately 20 min); Phase T2 (high load steady-state phase): 750℃ constant temperature for 11 hours and 40 minutes; Phase T3 (rapid load decrease and temperature drop phase): 750℃ to 450℃ at a rate of 15℃ / min (approximately 20 min); Phase T4 (low load steady-state phase): 450℃ constant temperature for 11 hours and 40 minutes. Phases T1–T4 constitute a 24-hour cycle, executed continuously for 7 cycles (7 days).

[0084] 2. Dynamic gas distribution settings (high-load oxidizing atmosphere and low-load reducing atmosphere under typical peak-shaving conditions)

[0085] The dynamic gas distribution system operates at a total flow rate of 2.00 L / min under standard conditions and at atmospheric pressure. Typical components representing the difference between oxidizing and reducing properties of boiler flue gas are selected and configured as two separate oxidizing and reducing atmospheres, which are synchronously switched during temperature rise / load drop phases.

[0086] Oxidizing atmosphere: CO2 0.30 L / min (15%), O2 0.10 L / min (5%), H2O (steam): 0.16 L / min (8%), N2 1.44 L / min (72%).

[0087] Reducing atmosphere: CO2 0.30 L / min (15%), CO 0.10 L / min (5%), H2O (steam): 0.20 L / min (10%), N2 1.40 L / min (70%).

[0088] The stages correspondence is as follows:

[0089] Stage G1 (corresponding to T1: rapid heating stage): The atmosphere switches from reducing to oxidizing; Stage G2 (corresponding to T2: high load steady-state stage): The oxidizing atmosphere is maintained; Stage G3 (corresponding to T3: rapid cooling stage): The atmosphere switches from oxidizing to reducing; Stage G4 (corresponding to T4: low load steady-state stage): The reducing atmosphere is maintained. During ventilation, the temperature of the electric heating tape is maintained at around 150℃ to prevent water vapor condensation.

[0090] To better reflect the actual flue gas corrosion environment, ppm-level SO2, HCl, etc. can be added as impurity gases without changing the flow ratio of the main components. The temperature and atmosphere conditions can also be dynamically set based on the actual measured boiler atmosphere and temperature in the power plant.

[0091] 3. Preparation of weightless samples

[0092] Cut 15CrMoG steel into 28 pieces of 8. 8 Small metal blocks (4mm in diameter) were used to polish each weightless sample with 1200-grit sandpaper and then with a polishing cloth to remove oxidation marks. The samples were then rinsed with deionized water, dried, and weighed. During the experiment, the weightless blocks were divided into 7 groups of 4 blocks each, placed in a ceramic boat. Three blocks were used for weight loss analysis, and the remaining one for characterization. Every 24 hours after the start of the experiment, one group of weightless blocks was removed, and one block was encapsulated in epoxy resin. After solidification, its corrosion cross-section was polished for SEM and EDS characterization analysis. The weight loss measurement process was performed according to the national standard GB / T16545-2015 to obtain the corrosion thickness during the corrosion process.

[0093] Resistance method for measuring parameters

[0094] The required corrosion rate response can be customized. In this embodiment, a resistance value is measured every 30 seconds with the measurement range set to automatic. The test clip is attached to the two ends of the resistor's wires. After setting the measurement speed and range parameters, a data storage folder is created, and the Merrick RK2517-4 resistance meter can automatically measure the resistance. The resistance is continuously measured and recorded during the experiment. The resistance-temperature calibration relationship is performed according to S101 and S103 of Example 1. After the experiment, the real-time corrosion thickness is calculated according to S5 of Example 1.

[0095] Coupling / Decoupling Comparison Operating Conditions

[0096] Decoupled research can be achieved by controlling variables such as temperature and atmosphere, and adjustments can be made according to research needs.

[0097] Coupled operating condition group: Temperature is switched synchronously according to T1–T4, and atmosphere is switched synchronously according to G1–G4;

[0098] Temperature decoupling group: Temperature is set according to T1–T4, and the atmosphere is fixed as oxidizing / reducing atmosphere throughout the process;

[0099] Atmosphere decoupling group: The temperature is kept constant at the highest circulating temperature of 750℃ (or the lowest circulating temperature of 450℃), and the atmosphere is switched between oxidizing and reducing atmospheres according to G1–G4.

[0100] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A flexible peak-shaving heated surface corrosion online monitoring simulation device based on the resistance method, characterized in that, include: The programmable temperature control module (1) is used to provide the test space and heat or cool the test space. The corrosion measurement module (2) includes a real-time corrosion measurement unit and a weight loss test unit set in the program temperature control module (1). The real-time corrosion measurement unit is used to measure the corrosion behavior of the boiler heating surface material under simulated working conditions online, and the weight loss test unit is used to verify the corrosion behavior of the boiler heating surface material under simulated working conditions offline. The dynamic gas distribution module (4) is used to provide the program temperature control module (1) with a corrosive atmosphere whose composition and flow rate change over time; The central synchronization control module (3) is used to synchronously control the temperature of the program temperature control module (1) and the gas distribution of the dynamic gas distribution module (4) based on a unified time reference. The pipeline heating module (5) is used to heat and insulate the gas pipeline between the dynamic gas distribution module (4) and the program temperature control module (1); The exhaust gas treatment module (6) is used to purify the experimental exhaust gas discharged from the program temperature control module (1).

2. The flexible peak-shaving heated surface corrosion online monitoring simulation device based on the resistance method according to claim 1, characterized in that, The program temperature control module (1) is a tubular furnace, the real-time corrosion measurement unit is a test resistor, the test resistor includes a bending part, the test resistor is made of the same material as the boiler heating surface material, the weight loss test unit includes multiple metal samples, used to calculate the average corrosion thickness based on mass loss, the metal samples are made of the same material as the boiler heating surface material, the dynamic gas distribution module (4) includes multiple gas supply units, a mass flow controller and a premixed heating unit, the multiple gas supply units are used to provide two or more gases including nitrogen, oxygen, carbon dioxide, sulfur dioxide, carbon monoxide, water vapor and hydrogen chloride, the mass flow controller and the multiple gas supply units The unit is connected to regulate the flow rate of each gas. The premixed heating unit is connected to the mass flow controller and is used to mix and heat two or more gases. The mixed gas heated to the predetermined temperature is sent to the program temperature control module (1). The central synchronous control module (3) is used to send the temperature program to the program temperature control module (1) and the gas distribution program to the dynamic gas distribution module (4). The temperature program and the gas distribution program are configured as follows: a coupled working condition in which the temperature and atmosphere composition change synchronously with time; a temperature decoupling working condition in which the temperature changes with time while the atmosphere composition remains constant; and an atmosphere decoupling working condition in which the atmosphere composition changes with time while the temperature remains constant, so as to realize the coupling and decoupling simulation of important corrosion factors under flexible peak-shaving working conditions.

3. The flexible peak-shaving heated surface corrosion online monitoring simulation device based on the resistance method according to claim 2, characterized in that, The programmed temperature control module (1) has a programmed temperature rise and fall range of 25℃ to 1200℃, and a heating or cooling rate of not less than 15℃ / min.

4. The online monitoring and simulation device for flexible peak-shaving heated surface corrosion based on the resistance method according to claim 2, characterized in that, It also includes a temperature compensation measurement unit for establishing a resistance-temperature calibration relationship in a non-corrosive environment. The temperature compensation measurement unit includes an inert gas supply unit connected to both the program temperature control module (1) and the central synchronization control module (3) and a temperature compensation resistor connected to the central synchronization control module (3). The temperature compensation resistor has the same structure and material as the test resistor. When the temperature compensation resistor is working, it is located inside the program temperature control module (1).

5. The flexible peak-shaving heated surface corrosion online monitoring simulation device based on the resistance method according to claim 2, characterized in that, The central synchronization control module (3) includes a potentiostat connected to the corrosion measurement module (2) and a computer connected to the potentiostat. The potentiostat applies a constant voltage to the test resistor and measures the resistance value of the test resistor at preset time intervals. The corrosion thickness and average corrosion rate of the test resistor are calculated by the change in the resistance value of the test resistor.

6. The flexible peak-shaving heated surface corrosion online monitoring simulation device based on the resistance method according to claim 1, characterized in that, The pipeline heating module (5) heats the gas pipeline between the dynamic gas distribution module (4) and the program temperature control module (1) to above 150°C.

7. A method for online monitoring and simulation of corrosion on flexible peak-shaving heated surfaces based on resistance method, using the online monitoring and simulation device for corrosion on flexible peak-shaving heated surfaces based on resistance method as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Install a corrosion real-time measurement unit in the furnace cavity of the program temperature control module (1) and arrange the metal sample of the weight loss test unit. The corrosion real-time measurement unit is connected to the central synchronous control module (3) through a wire. S2. Set the temperature program and gas distribution program in the central synchronous control module (3). According to the experimental purpose, configure the two as a coupled program where the temperature and atmosphere change synchronously, a temperature decoupling program where the temperature changes while the atmosphere remains constant, or an atmosphere decoupling program where the atmosphere changes while the temperature remains constant, and send them to the program temperature control module (1) and the dynamic gas distribution module (4) respectively. S3, The program temperature control module (1) changes the furnace temperature according to the temperature program. At the same time, the dynamic gas distribution module (4) adjusts the flow rate of each gas in the various gases according to the gas distribution program. After being mixed and heated by the premixed heating unit, the gas is sent into the furnace, so that the corrosion real-time measurement unit is under the target coupling or decoupling corrosion condition. S4. The potentiostat performs resistance measurements on the corrosion real-time measurement unit at preset time intervals, and the computer records the real-time data of resistance changes over time. S5. The resistance data of the real-time corrosion measurement unit is temperature compensated using the resistance-temperature calibration relationship. The cross-sectional area change and corrosion thickness change of the test resistance at each measurement time point are calculated, and the average corrosion rate within the corresponding time period is obtained, so as to realize the in-situ online monitoring of the corrosion behavior of the real-time corrosion measurement unit. S6. Weigh the metal sample in the weight loss test unit, calculate the average corrosion thickness during the experimental period, and compare it with the online measurement results obtained in step S5.

8. The online monitoring and simulation method for corrosion of flexible peak-shaving heated surfaces based on the resistance method according to claim 7, characterized in that, In step S5, the resistance-temperature calibration relationship is obtained through a temperature compensation measurement unit, and the process includes the following steps: S101. Before step S1, place the temperature compensation resistor inside the furnace cavity of the program temperature control module (1), and connect the temperature compensation resistor to the central synchronous control module (3) through a wire. S102, the program temperature control module (1) heats up, and the inert gas supply unit supplies inert gas into the furnace cavity of the program temperature control module (1); S103, the potentiostat of the central synchronous control module (3) measures the resistance value of the temperature compensation resistor at preset time intervals to establish the resistance-temperature calibration relationship under non-corrosive environment.

9. The online monitoring and simulation method for corrosion of flexible peak-shaving heated surfaces based on the resistance method according to claim 7, characterized in that, The metal samples in the weight loss test unit are characterized and analyzed, including: observing the surface and cross-sectional morphology of the corrosion products using a scanning electron microscope; analyzing the elemental distribution of the corrosion products using an energy dispersive spectroscopy (EDS) instrument; and analyzing the phase composition of the corrosion products using an X-ray diffractometer.

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