Experimental apparatus and method for simulating fouling growth on the secondary side heat transfer tubes of an OTSG

Abstract

This invention discloses an experimental apparatus and method for simulating fouling growth in the secondary side heat transfer tube of an OTSG (Optical Transfer Heat Exchanger). The apparatus includes a first drive device, a heater, and a heating chamber located on the primary side circulation loop; a liquid storage container, a second drive device, and a heat transfer tube located on the secondary side circulation loop; and an online feeding device connected to the liquid storage container on the secondary side. The heat transfer tube is disposed within the heating chamber. The first drive device drives the medium in the primary side circulation loop to circulate, and the medium, after being heated by the heater, transfers heat to the heat transfer tube in the heating chamber. The online feeding device injects corrosion products into the liquid storage container, and the second drive device drives the medium in the liquid storage container to circulate in the secondary side circulation loop. After being heated in the heat transfer tube, the medium ejects steam at the outlet of the heat transfer tube, and the corrosion products accumulate as fouling within the heat transfer tube. This invention can obtain the fouling distribution in different flow heat transfer regions of the heat transfer tube in a short time.

Description

Technical Field

[0001] This invention relates to the field of OTSG secondary side heat transfer tube technology, and in particular to a test apparatus and test method for simulating fouling growth in OTSG secondary side heat transfer tubes. Background Technology

[0002] A steam generator is a heat exchanger that transfers heat generated in the primary loop of a nuclear reactor to the secondary loop, thereby converting thermal energy into electrical energy. In large pressurized water reactors, a U-tube steam generator (UTSG) is typically used. In small nuclear reactors, a once-through steam generator (OTSG) is usually used instead of a UTSG. OTSGs utilize a multi-layered spiral heat transfer tube structure to maximize heat transfer capacity within limited height and volume by increasing the flow heat transfer area. During power operation, the secondary-side medium undergoes a phase change process within this spiral structure, gradually transforming from a subcooled to a superheated state. Since the secondary loop equipment uses a significant amount of carbon steel, corrosion products during this phase change form a mixture of Fe2O3 and Fe3O4 in the medium. These iron oxides continuously deposit on the secondary-side heat transfer tubes of the OTSG, forming fouling and affecting the OTSG's heat transfer efficiency, operational safety, and stability. The flow characteristics of the secondary medium in an OTSG are complex, including subcooled, two-phase, and superheated regions. The thickness, density, and heat transfer coefficient of the fouling in different regions vary greatly. Analyzing the fouling on the secondary side of an actual operating OTSG makes it difficult to obtain the fouling characteristics of different flow regions, and the testing cost is high. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address at least one deficiency of the related technologies mentioned in the background: it is difficult to obtain the fouling characteristics of different flow regions when analyzing the fouling on the secondary side of an OTSG in actual operation, and the detection cost is high. The present invention provides a test device and test method for simulating the fouling growth of the secondary side heat transfer tube of an OTSG.

[0004] The technical solution adopted by this invention to solve its technical problem is: constructing an experimental device for simulating fouling growth on the secondary side heat transfer tube of an OTSG, comprising: The first drive unit, heater, and heating chamber are located on the primary side circulation loop; A liquid storage container, a second drive device, and a heat transfer tube located on the secondary side circulation loop; and an online feeding device located on the secondary side and connected to the liquid storage container; The heat transfer tube is located inside the heating chamber. The first driving device drives the medium in the primary circulation loop to circulate. After being heated by the heater, the medium transfers heat to the heat transfer tube in the heating chamber. The online feeding device is used to inject corrosion products into the liquid storage container. The second driving device drives the medium in the liquid storage container to circulate in the secondary side circulation loop. After being heated in the heat transfer tube, the medium sprays steam out at the outlet of the heat transfer tube, and the corrosion products accumulate scale in the heat transfer tube.

[0005] Preferably, the experimental apparatus for simulating fouling growth on the secondary side heat transfer tube of an OTSG according to the present invention further includes: a first heating controller located on the primary side and electrically connected to the heater, for adjusting the heating power of the heater.

[0006] Preferably, the experimental apparatus for simulating fouling growth on the secondary side heat transfer tube of the present invention further includes: a preheater located on the secondary side circulation loop between the liquid storage container and the inlet end of the heat transfer tube, used to reduce the difference between the temperature of the subcooled medium at the inlet end of the heat transfer tube and the saturation temperature corresponding to the pressure at which the medium is located.

[0007] Preferably, the experimental apparatus for simulating fouling growth on the secondary side heat transfer tube of the OTSG according to the present invention further includes: an auxiliary heater located on the secondary side circulation loop connecting the outlet end of the heat transfer tube and the inlet end of the liquid storage container, used to increase the difference between the temperature of the superheated medium at the outlet end of the heat transfer tube and the saturation temperature corresponding to the pressure of the medium.

[0008] Preferably, the experimental apparatus for simulating fouling growth on the secondary side heat transfer tube of an OTSG according to the present invention further includes: a second heating controller located on the secondary side and electrically connected to the auxiliary heater, for adjusting the heating power of the auxiliary heater.

[0009] Preferably, in the experimental apparatus for simulating fouling growth on the secondary side heat transfer tube of an OTSG according to the present invention, the online feeding device includes: an electrode and a metal component; the electrode generates current after being energized, and the metal component generates corrosion products through electrolysis, which then enter the liquid storage container.

[0010] Preferably, the experimental apparatus for simulating fouling growth on the secondary side heat transfer tube of an OTSG according to the present invention further includes: a pressure relief device located on the secondary side and connected to the liquid storage container, used to control the pressure of the secondary side circulation loop.

[0011] Preferably, the experimental apparatus for simulating fouling growth on the secondary side heat transfer tube of an OTSG according to the present invention further includes: a feeding device located on the secondary side and connected to the liquid storage container, for injecting an acid or alkaline medium into the liquid storage container; and / or an air supply device located on the secondary side and connected to the liquid storage container, for injecting soluble oxygen into the liquid storage container. And / or, a filter located on the secondary side circulation loop between the liquid storage container and the inlet end of the heat transfer tube, for filtering impurities in the medium.

[0012] Preferably, the experimental apparatus for simulating fouling growth on the secondary side heat transfer tube of an OTSG according to the present invention further includes: A pressure measuring device, located on the secondary side circulation loop, is used to measure the pressure at a corresponding position in the secondary side circulation loop; and / or A flow rate regulator, disposed in the primary circulation loop and / or the secondary circulation loop, and used to regulate the flow rate of the medium in the primary circulation loop and / or the secondary circulation loop; and / or A temperature measuring device is installed on the secondary side circulation loop and is used to measure the temperature at the corresponding position in the secondary side circulation loop.

[0013] The present invention also provides a test method for the test apparatus for simulating fouling growth on the secondary side heat transfer tube of an OTSG as described in any of the above claims, comprising the following steps: S1: Start the first driving device, the second driving device and the heater. Drive the medium in the primary side circulation loop to circulate through the first driving device. After being heated by the heater, the medium transfers heat to the heat transfer tube in the heating chamber. Drive the medium in the liquid storage container to circulate through the secondary side circulation loop through the second driving device. After being heated in the heat transfer tube, the medium sprays steam out of the heat transfer tube outlet. S2: Start the online feeding device and inject corrosion products into the liquid storage container through the online feeding device. The corrosion products accumulate in the heat transfer tube under the flow of the medium. S3: After running for a preset time period, stop the online feeding device, the first driving device, the second driving device and the heater, drain the medium in the secondary side circulation loop, and allow the medium in the primary side circulation loop to cool naturally to room temperature; S4: Remove the heat transfer tubes and analyze the parameters of each region to form a dataset on the impact of fouling on the secondary side heat transfer tubes of the OTSG on its heat exchange performance.

[0014] By implementing this invention, the following beneficial effects are achieved: In actual service, the secondary side heat transfer tubes of OTSG require more than a year to grow fouling. Using this device, test samples similar to actual fouling can be obtained within one week, which significantly shortens the fouling growth time and reduces the testing cost.

[0015] It is difficult to obtain the fouling distribution of the secondary side heat transfer tubes in actual operation. However, by using the test device mentioned in this invention, the fouling distribution of different flow heat transfer regions of the OTSG secondary side heat transfer tubes can be obtained, which is beneficial for evaluating the differences in fouling of the OTSG secondary side heat transfer tubes.

[0016] Detecting fouling on the secondary side heat transfer tubes of an OTSG in actual operation only yields fouling data for a portion of the area after reactor shutdown. This invention, by controlling the test time, obtains fouling data at different time points to simulate the dynamic growth and change process of fouling on the secondary side heat transfer tubes of the OTSG during operation. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a schematic diagram of the experimental apparatus for simulating fouling growth in the secondary side heat transfer tubes of an OTSG according to the present invention; Figure 2 This is a flowchart of the test method for the experimental apparatus of the present invention for simulating fouling growth on the secondary side heat transfer tube of an OTSG. Detailed Implementation

[0018] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0020] In the description of the invention, it should be understood that the terms "front," "rear," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of the invention, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or a chemical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] like Figure 1 As shown, one embodiment of the present invention discloses a test apparatus for simulating fouling growth on the secondary side heat transfer tube of an OTSG, comprising: The first drive unit 11, heater 13 and heating chamber 16 are located on the primary side circulation loop; The liquid storage container 18, the second drive device 24, and the heat transfer tube 28 are located on the secondary side circulation loop; and the online feeding device 17 connected to the liquid storage container 18 is located on the secondary side.

[0023] The heat transfer tube 28 is located in the heating chamber 16. The first driving device 11 drives the medium in the primary circulation loop to circulate. After being heated by the heater 13, the medium transfers heat to the heat transfer tube 28 in the heating chamber 16.

[0024] The online feeding device 17 is used to inject corrosion products into the liquid storage container 18. The second driving device 24 drives the medium in the liquid storage container 18 to circulate in the secondary side circulation loop. After the medium is heated in the heat transfer tube 28, steam is ejected from the outlet of the heat transfer tube 28, and the corrosion products accumulate in the heat transfer tube 28.

[0025] For example, the medium in the primary circulation loop can be water or liquid metal, etc. The medium in the secondary circulation loop can be water, etc. The first drive device 11 and the second drive device 24 are water pumps, used to provide power for the stable flow of the medium in the circulation loop. The liquid storage container 18 is used to provide the medium to the secondary circulation loop. The heater 13 is used to simulate the heat energy generated on the primary side of the OTSG. The heating chamber 16 is a heating ring cavity, used to simulate the area where heat energy is transferred from the primary side of the OTSG to the secondary side heat transfer tube 28.

[0026] In this embodiment, the test apparatus further includes a first heating controller 14 located on the primary side and electrically connected to the heater 13, for adjusting the heating power of the heater 13. For example, the first heating controller 14 is a power controller.

[0027] In this embodiment, the test apparatus further includes a preheater 25 located on the secondary circulation loop between the liquid storage container 18 and the inlet end of the heat transfer tube 28. The preheater 25 is used to reduce the temperature difference (subcooling) between the subcooled medium (liquid medium) at the inlet end of the heat transfer tube 28 and the saturation temperature corresponding to the pressure at which the medium is located, i.e., to heat the medium at the inlet end of the heat transfer tube 28 to the target temperature. Preferably, the preheater 25 is connected to the outlet end of the second drive device 24 and the inlet end of the heat transfer tube 28.

[0028] Furthermore, the experimental apparatus also includes an auxiliary heater 31 located on the secondary circulation loop, connecting the outlet end of the heat transfer tube 28 and the inlet end of the liquid storage container 18. This auxiliary heater is used to increase the difference between the temperature of the superheated medium (steam) at the outlet end of the heat transfer tube 28 and the saturation temperature corresponding to the pressure at which the medium is located (superheat), that is, to continue heating the steam ejected from the heat transfer tube 28, thereby increasing the superheat at the outlet end of the heat transfer tube 28. For example, the auxiliary heater 31 is a heat exchanger.

[0029] In addition, the test apparatus also includes a second heating controller 32 located on the secondary side and electrically connected to the auxiliary heater 31, for adjusting the heating power of the auxiliary heater 31. For example, the second heating controller 32 is a power controller.

[0030] The main heat source in the circulation loop is heater 13, and preheater 25 is an auxiliary heat source. If heater 13 and preheater 25 work together but still cannot achieve a high level of superheat at the outlet of heat transfer tube 28, then auxiliary heater 31 will be put into use to heat the outlet of heat transfer tube 28 and increase the local superheat.

[0031] Controlling subcooling is relatively easier. In the most extreme case, only heater 13 is working, while preheater 25 and auxiliary heater 31 are not in operation, which can achieve a large degree of subcooling.

[0032] By using the preheater 25 and the auxiliary heater 31, the subcooling at the inlet end and the superheat at the outlet end of the OTSG secondary side heat transfer tube 28 can be adjusted to a range close to the operating conditions. By controlling the subcooling and superheat, the flow heat transfer characteristics of different regions of the OTSG secondary side heat transfer tube can be simulated, ensuring that the test sample heat transfer tube 28 can generate key areas that affect the growth and distribution of fouling, such as the subcooled zone, the two-phase zone, and the superheated zone.

[0033] In this embodiment, the online feeding device 17 includes an electrode 171 and a metal component 172. When the electrode 171 is energized, it generates current, causing corrosion products to form on the metal component 172 through electrolysis, simulating the corrosion of the OTSG heat transfer tube 28 during operation. The corrosion products enter the storage container 18. Since the medium in the storage container 18 also circulates, the corrosion products entering the storage container 18 are flushed to the area of ​​the heat transfer tube 28 by the medium and then deposited. For example, the metal component 172 is an iron disc.

[0034] In this embodiment, the test apparatus further includes a pressure relief device 21 located on the secondary side and connected to the liquid storage container 18, used to control the pressure of the secondary side circulation loop. When the pressure is too high, liquid is discharged to avoid excessive pressure. For example, the pressure relief device 21 is a pressure relief valve.

[0035] In this embodiment, the experimental apparatus further includes a packing device 19 located on the secondary side and connected to the storage container 18, used to inject acid-base media into the storage container 18 to maintain the pH value of the secondary side circulation loop at approximately 7.0. Depending on the experimental requirements, the pH range can be extended to between 6.0 and 8.0 by adjusting the acid-base media ratio. The packing device 19 includes a container 191 for holding the acid-base media, a third driving device 192, and a switching device 193. For example, the third driving device 19 is a water pump, and the switching device 193 is a valve.

[0036] In this embodiment, the test apparatus further includes an air supply device 20 located on the secondary side and connected to the liquid storage container 18, used to inject soluble oxygen into the liquid storage container 18 to ensure that the medium in the secondary side circulation loop is in an oxidizing environment, the same as the water environment on the secondary side of the OTSG. For example, the air supply device 20 is an air supply valve.

[0037] In this embodiment, the experimental apparatus further includes a filter 22 located on the secondary circulation loop between the liquid storage container 18 and the inlet end of the heat transfer tube 28, for filtering impurities in the medium. Preferably, the filter 22 is located on the secondary circulation loop connecting the outlet end of the liquid storage container 18 and the inlet end of the second drive device 24. It should be noted that the precipitation inside the heat pipe is formed by a thermal phase change, and the filter 22 filters impurities that are already present in the medium, thereby making the simulation results more accurate.

[0038] In this embodiment, the test apparatus further includes a pressure measuring device located on the secondary side circulation loop and used to measure the pressure at the corresponding location in the secondary side circulation loop. Specifically, in some embodiments, the test apparatus for simulating fouling growth on the secondary side heat transfer tube of an OTSG may include: a first pressure measuring device 23 located on the secondary side circulation loop, connecting the outlet end of the liquid storage container 18 and the inlet end of the second drive device 24, used to measure the pressure at the inlet end of the second drive device 24. And / or, a second pressure measuring device 33 located on the secondary side circulation loop, connecting the outlet end of the heat transfer tube 28 and the inlet end of the liquid storage container 18, used to measure the pressure at the outlet end of the heat transfer tube 28. For example, the first pressure measuring device 23 and the second pressure measuring device 33 are pressure gauges.

[0039] In this embodiment, the test apparatus further includes a flow rate regulator, which is located in the primary test circulation loop and / or the secondary side circulation loop, and is used to regulate the flow rate of the medium in the primary test circulation loop and / or the secondary side circulation loop.

[0040] For example, a flow rate regulator can be located in the primary circulation loop to regulate the flow rate of the medium in the primary circulation loop. Specifically, in some embodiments, the test apparatus for simulating fouling growth on the secondary side heat transfer tube of an OTSG may include: a first flow rate regulator 12 located on the primary circulation loop, connecting the outlet end of the first drive device 11 and the inlet end of the heater 13, for regulating the flow rate of the cooling medium entering the heater 13. And / or, a second flow rate regulator 15 located on the primary circulation loop, connecting the outlet end of the heater 13 and the inlet end of the heating chamber 16, for regulating the flow rate of the heated cooling medium entering the heating chamber 16. For example, the first flow rate regulator 12 and the second flow rate regulator 15 are valves.

[0041] For example, a flow rate regulator can be located in the secondary circulation loop to regulate the flow rate of the medium in the secondary circulation loop. Specifically, in some embodiments, the test apparatus for simulating fouling growth on the secondary side heat transfer tube of an OTSG may further include: a third flow rate regulator 26 located on the secondary circulation loop, connecting the outlet end of the second drive device 24 and the inlet end of the heat transfer tube 28, for regulating the flow rate of the medium entering the heat transfer tube 28. And / or, a fourth flow rate regulator 30 located on the secondary circulation loop, connecting the outlet end of the heat transfer tube 28 and the inlet end of the liquid storage container 18, for regulating the flow rate of the medium entering the liquid storage container 18 after being heated by the heat transfer tube 25. For example, the third flow rate regulator 26 and the fourth flow rate regulator are valves, which can adjust the temperature and pressure of the medium in the loop by changing the flow rate.

[0042] In some embodiments, the experimental apparatus for simulating fouling growth on the secondary side heat transfer tube of an OTSG may further include a fifth flow rate regulator 34 located on the secondary side circulation loop, connecting the outlet end of the auxiliary heater 31 and the inlet end of the liquid storage container 18, for regulating the flow rate of the medium entering the liquid storage container 18 after being heated by the auxiliary heater 31. Correspondingly, a fourth flow rate regulator 30 is connected to the outlet end of the heat transfer tube 28 and the inlet end of the auxiliary heater 31, and the fourth flow rate regulator 30 is used to regulate the flow rate of the medium entering the auxiliary heater 31. For example, the fifth flow rate regulator 34 is a valve.

[0043] In this embodiment, the test apparatus also includes a temperature measuring device, which is located on the secondary side circulation loop and is used to measure the temperature at the corresponding position in the secondary side circulation loop.

[0044] Specifically, the test apparatus may further include: a first temperature measuring device 27 located on the secondary side circulation loop, connecting the outlet end of the preheater 25 and the inlet end of the heat transfer tube 28, for measuring the medium temperature at the inlet end of the heat transfer tube 28; and a second temperature measuring device 29 located on the secondary side circulation loop, connecting the outlet end of the heat transfer tube 28 and the inlet end of the auxiliary heater 31, for measuring the steam temperature at the outlet end of the heat transfer tube 28.

[0045] Furthermore, the second heating controller 32 can control the heating power of the auxiliary heater 31 online based on data from the second temperature measuring device 29 and the second pressure measuring device 33. The fourth flow rate regulator 30 and the fifth flow rate regulator 34 adjust their opening degree according to the target value provided by the second heating controller 32, thereby adjusting the temperature and pressure of the circuit. In some other embodiments, the test apparatus may also include a third heating controller, which can control the heating power of the preheater 25 online based on data from the first temperature measuring device 27 and the first pressure measuring device 23.

[0046] Completely, the primary circulation loop includes a first drive device 11, a first flow rate regulator 12, a heater 13, a second flow rate regulator 15, and a heating chamber 16 connected end to end. Among them, the first heating controller 14 is electrically connected to the heater 13.

[0047] The secondary circulation loop includes a liquid storage container 18, a filter 22, a first pressure measuring device 23, a second drive device 24, a preheater 25, a third flow rate regulator 26, a first temperature measuring device 27, a heat transfer tube 28, a second temperature measuring device 29, a fourth flow rate regulator 30, an auxiliary heater 31, a second pressure measuring device 33, and a fifth flow rate regulator 34, all connected end-to-end. An online feeding device 17, a pressure relief device 21, a third drive device 19, and an air supply device 20 are all connected to the liquid storage container 18. A second heating control 32 is electrically connected to the auxiliary heater 31.

[0048] like Figure 2As shown, one embodiment of the present invention discloses a test method for a test apparatus based on the above embodiment for simulating fouling growth on the secondary side heat transfer tube of an OTSG, comprising the following steps: S1: Start the first drive device 11, the second drive device 24 and the heater 13. The first drive device 11 drives the medium in the primary circulation loop to circulate. After being heated by the heater 13, the medium transfers heat to the heat transfer tube 28 in the heating chamber 16. The second drive device 24 drives the medium in the liquid storage container 18 to circulate in the secondary circulation loop. After being heated in the heat transfer tube 28, the medium sprays steam out at the outlet of the heat transfer tube 28.

[0049] Specifically, the first drive unit 11, the second drive unit 24, the heater 13, the first heating controller 14, the preheater 25, the auxiliary heater 31, and the second heating controller 32 are activated. The pressure and temperature of the medium in the secondary side circulation loop are monitored by the first pressure measuring device 23, the first temperature measuring device 27, the second pressure measuring device 33, and the second temperature measuring device 29. The preheater 25, the auxiliary heater 31, and the second heating controller 32 adjust the subcooling at the inlet and the superheat at the outlet of the OTSG secondary side heat transfer tube 28 to a range close to the operating conditions. By controlling the subcooling and superheat, the flow heat transfer characteristics of different regions of the OTSG secondary side heat transfer tube are simulated, ensuring that the test sample heat transfer tube 28 can generate key areas affecting fouling growth and distribution, such as subcooled zones, two-phase zones, and superheated zones. Furthermore, the pressure is adjusted to a range close to the actual operating conditions by the third flow rate regulator 26, the fourth flow rate regulator 30, and the fifth flow rate regulator 34. The purpose of this step is to ensure that the thermal-hydraulic parameters of the test loop can characterize the actual service environment of the OTSG before the formal commencement of the fouling deposition test.

[0050] S2: Start the online feeding device 17 and inject the corrosion products into the liquid storage container 18 through the online feeding device 17. The corrosion products accumulate in the heat transfer tube 28 under the flow of the medium.

[0051] Specifically, the electrode 171 is activated. After the electrode 171 is energized, it generates current. Through electrolysis, the metal part 172 continuously produces corrosion products to simulate the corrosion of the OTSG heat transfer tube 28 during operation. The corrosion products enter the liquid storage container 18. Since the medium in the liquid storage container 18 also circulates, the corrosion products entering the liquid storage container 18 will be flushed to the area of ​​the heat transfer tube 28 by the medium and then deposited.

[0052] S3: After running for a preset time period, stop the online feeding device 17, the first drive device 11, the second drive device 24 and the heater 13, drain the medium in the secondary side circulation loop, and naturally cool the medium in the primary side circulation loop to room temperature.

[0053] Specifically, after approximately one week of stable operation, the online feeding device 17, the first drive device 11, the second drive device 24, the heater 13, the first heating controller 14, the preheater 25, the auxiliary heater 31, and the second heating controller 32 are stopped. The pressure relief device 21 is then opened to quickly drain the medium from the secondary circulation loop, reducing the amount of scale dissolving into the medium during cooling. This ensures that the samples taken after cooling can characterize the OTSG scale buildup characteristics during operation. For the medium in the primary circulation loop, it is allowed to cool naturally to room temperature.

[0054] S4: Remove heat transfer tube 28 and analyze the parameters of each region to form a dataset on the impact of fouling on the secondary side heat transfer tube 28 of the OTSG on its heat exchange performance.

[0055] Specifically, heat transfer tube 28 was removed and sliced ​​in its axial and radial directions. Using scanning electron microscopy and X-ray photoelectron spectroscopy, parameters such as the thickness, morphology, chemical composition and heat transfer coefficient of the fouling in each region were analyzed to form a data matrix of the influence of fouling on the heat transfer performance of the OTSG secondary side heat transfer tube 28.

[0056] By implementing this invention, the following beneficial effects are achieved: In actual service, the secondary side heat transfer tubes of OTSG require more than a year to grow fouling. Using this device, test samples similar to actual fouling can be obtained within one week, which significantly shortens the fouling growth time and reduces the testing cost.

[0057] It is difficult to obtain the fouling distribution of the secondary side heat transfer tubes in actual operation. However, by using the test device mentioned in this invention, the fouling distribution of different flow heat transfer regions of the OTSG secondary side heat transfer tubes can be obtained, which is beneficial for evaluating the differences in fouling of the OTSG secondary side heat transfer tubes.

[0058] Detecting fouling on the secondary side heat transfer tubes of an OTSG in actual operation only yields fouling data for a portion of the area after reactor shutdown. This invention, by controlling the test time, obtains fouling data at different time points to simulate the dynamic growth and change process of fouling on the secondary side heat transfer tubes of the OTSG during operation.

[0059] It is understood that the above embodiments only illustrate some implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that for those skilled in the art, without departing from the concept of the present invention, the above embodiments or technical features can be freely combined, and several modifications and improvements can be made. These all fall within the protection scope of the present invention. That is, the embodiments described "in some embodiments" can be freely combined with any of the embodiments above and below. Therefore, all equivalent transformations and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A test apparatus for simulating fouling growth on the secondary side heat transfer tube of an OTSG, characterized in that, include: The first drive unit (11), heater (13) and heating chamber (16) are located on the primary side circulation loop. The liquid storage container (18), the second drive device (24), and the heat transfer tube (28) are located on the secondary side circulation loop. An online feeding device (17) is located on the secondary side and connected to the liquid storage container (18); the online feeding device (17) includes an electrode (171) and a metal part (172). When the electrode (171) is energized, it generates current and causes the metal part (172) to produce corrosion products through electrolysis, which then enter the liquid storage container (18). A preheater (25) located on the secondary side circulation loop between the outlet end of the second drive device (24) and the inlet end of the heat transfer tube (28) is used to reduce the difference between the temperature of the subcooled medium at the inlet end of the heat transfer tube (28) and the saturation temperature corresponding to the pressure at which the medium is located; and, An auxiliary heater (31) located on the secondary side circulation loop, connecting the outlet end of the heat transfer tube (28) and the inlet end of the liquid storage container (18), is used to increase the difference between the temperature of the superheated medium at the outlet end of the heat transfer tube (28) and the saturation temperature corresponding to the pressure of the medium. The pressure relief device (21) located on the secondary side and connected to the liquid storage container (18) is used to control the pressure of the secondary side circulation loop; The heat transfer tube (28) is located in the heating chamber (16). The first driving device (11) drives the medium in the primary circulation loop to circulate. After being heated by the heater (13), the medium transfers heat to the heat transfer tube (28) in the heating chamber (16). The online feeding device (17) is used to inject corrosion products into the liquid storage container (18). The second driving device (24) drives the medium in the liquid storage container (18) to circulate in the secondary side circulation loop. After being heated in the heat transfer tube (28), the medium sprays steam out of the outlet of the heat transfer tube (28), and the corrosion products accumulate scale in the heat transfer tube (28).

2. The test apparatus for simulating secondary side heat tube fouling growth of an OTSG as recited in claim 1 wherein, Also includes: A first heating controller (14) located on the primary side and electrically connected to the heater (13) is used to adjust the heating power of the heater (13).

3. The test apparatus for simulating secondary side heat tube fouling growth of an OTSG as recited in claim 1 wherein, Also includes: A second heating controller (32), located on the secondary side and electrically connected to the auxiliary heater (31), is used to adjust the heating power of the auxiliary heater (31).

4. The test apparatus for simulating secondary side heat tube fouling growth of an OTSG as recited in claim 1 wherein, Also includes: A feeding device (19) located on the secondary side and connected to the liquid storage container (18) is used to inject acid and alkali media into the liquid storage container (18); and / or, an air supply device (20) located on the secondary side and connected to the liquid storage container (18) is used to inject soluble oxygen into the liquid storage container (18). And / or, a filter (22) located on the secondary side circulation loop between the liquid storage container (18) and the inlet end of the heat transfer tube (28) for filtering impurities in the medium.

5. The experimental apparatus for simulating fouling growth on the secondary side heat transfer tube of an OTSG according to claim 1, characterized in that, Also includes: A pressure measuring device, located on the secondary side circulation loop, is used to measure the pressure at a corresponding position in the secondary side circulation loop; and / or A flow rate regulator, disposed in the primary circulation loop and / or the secondary circulation loop, and used to regulate the flow rate of the medium in the primary circulation loop and / or the secondary circulation loop; and / or A temperature measuring device is installed on the secondary side circulation loop and is used to measure the temperature at the corresponding position in the secondary side circulation loop.

6. A test method for testing the test apparatus for simulating the fouling growth of the secondary side heat transfer tubes of an OTSG as claimed in any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Start the first drive device (11), the second drive device (24), the heater (13), the preheater (25) and the auxiliary heater (31). Drive the medium in the primary side circulation loop through the first drive device (11). After being heated by the heater (13), the medium transfers heat to the heat transfer tube (28) in the heating chamber (16). Drive the medium in the liquid storage container (18) through the second drive device to circulate in the secondary side circulation loop. After being heated in the heat transfer tube (28), the medium sprays steam out of the outlet of the heat transfer tube (28). S2: Start the online feeding device (17) and inject the corrosion products into the liquid storage container (18) through the online feeding device (17). The corrosion products accumulate in the heat transfer tube (28) under the flow of the medium. It includes: activating the electrode (171), generating current after the electrode (171) is energized, causing the metal part (172) to continuously generate the corrosion products through electrolysis, the corrosion products entering the liquid storage container (18), the corrosion products being flushed to the heat transfer tube (28) area by the medium, and then depositing; S3: After running for a preset time period, stop the online feeding device (17), the first driving device (11), the second driving device (24), the heater (13), the preheater (25) and the auxiliary heater (31), open the pressure relief device (21), empty the medium in the secondary side circulation loop, and naturally cool the medium in the primary side circulation loop to room temperature; S4: Take out the heat transfer tube (28) and analyze the parameters of each region to form a dataset on the impact of fouling on the heat exchange performance of the OTSG secondary side heat transfer tube (28).

Images