Ammonia gas corrosion test device with circulation function

Abstract

The invention relates to the technical field of test equipment, in particular to a gas ammonia corrosion test device with a circulation function, which comprises a test kettle, a gas component control system, a gas circulation system and a temperature control system capable of moving and switching. The test kettle adopts a high-sealing design, so that reliable sealing of the kettle body and the kettle cover can be realized; the gas component control system realizes accurate proportioning of ammonia gas, air, oxygen and other multi-component gases through multi-path gas inlet and high-precision flow control; the gas circulating system drives gas to flow between the kettle and a circulating pipeline through a circulating pump, so that gas layering is avoided; and the temperature control system adopts a switchable low-temperature control unit and a switchable high-temperature control unit which are respectively connected with the kettle body through a lifting and horizontal moving structure, so that the test device has wide-temperature-range regulation and control capability. The gas ammonia corrosion test device can truly simulate a complex gas ammonia service environment, and the accuracy and reliability of a corrosion test are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of testing equipment technology, and more specifically, to a gaseous ammonia corrosion testing device with a circulation function. Background Technology

[0002] Against the backdrop of the deepening global "dual-carbon" strategy, ammonia, as a carbon-free and highly efficient new energy source, is gradually becoming one of the core carriers of energy transformation. Ammonia can not only serve as a storage and transportation medium for hydrogen energy but can also be directly used in key equipment such as ammonia-powered engines, large liquid ammonia storage tanks, and green ammonia production systems. During service, the core components of these devices are exposed to gaseous ammonia environments or mixtures of gaseous ammonia with air, oxygen, and other gases for extended periods. Their corrosion resistance and stress corrosion resistance directly determine the operational safety and service life of the equipment. Therefore, developing a gaseous ammonia testing device capable of accurately simulating the actual service conditions of relevant materials is of crucial practical significance for material performance testing and optimized design, and is also a key technological support for promoting the large-scale development of the ammonia energy industry.

[0003] Currently, there are significant limitations in the industry's testing methods for material properties under ammonia conditions, mainly manifested in two core issues: first, the unreasonable substitution of liquid ammonia testing devices for gaseous ammonia testing devices; and second, the inadequacy of existing gaseous ammonia testing devices in terms of the accuracy of operating condition simulation and the completeness of their functions.

[0004] In alternative solutions for liquid ammonia testing devices, existing technologies typically employ a "gas-top, liquid-bottom" structural design, where liquid ammonia is at the bottom and gaseous ammonia is at the top, attempting to simultaneously characterize the material's corrosion performance in both ammonia phases. However, this design fundamentally differs from actual service conditions: Firstly, in actual large liquid ammonia storage tanks transported at low temperatures and atmospheric pressure, the temperature of the liquid ammonia at the bottom can reach -33.5℃, while the temperature of the gaseous ammonia at the top is significantly different due to the influence of ambient temperature and direct sunlight. Furthermore, the incomplete insulation properties of the thermal insulation layer further exacerbate this temperature difference. In contrast, laboratory simulation devices are smaller and equipped with stable temperature control systems, resulting in essentially uniform temperatures between the upper and lower sections, failing to replicate the actual temperature difference environment. Secondly, in actual operation, when air is introduced into the storage tank, it preferentially enters the upper gaseous ammonia space and gradually mixes with the gaseous ammonia before slowly dissolving into the liquid ammonia below. Existing simulation devices often directly add air to the liquid ammonia, completely deviating from the actual gas mixing process. Furthermore, the working principle of an ammonia-powered engine involves preheating gaseous ammonia, mixing it with air, and igniting it at a specific temperature. Its core components face a high-temperature corrosive environment from the mixture of gaseous ammonia and air / oxygen, a complex gas mixture condition that liquid ammonia testing equipment cannot simulate. These differences directly lead to significant discrepancies between test results and the actual service performance of materials, making it difficult to provide reliable data for material selection and equipment design, and severely hindering the technological upgrading of related industries.

[0005] To improve the uniformity of ammonia distribution in the test environment, existing patent CN115290541A discloses an ammonia test chamber with an ammonia recovery mechanism. This device uses trapezoidal nozzles inside the test chamber and guide plates inside the nozzles to split the ammonia into two streams that exit from the side outlets. The outlets also employ a gradually changing length ventilation channel design to extend the ammonia flow path and slow down the gas rise velocity, thereby improving the uniformity of ammonia distribution within the test area to some extent. Furthermore, the device includes a gas collection bladder and a recovery mechanism to recover and reuse unreacted ammonia, reducing test costs. However, it still has the following limitations: First, the gas component control precision is insufficient. This device is mainly used for tests in a single ammonia environment and does not address the precise proportioning and mixing control of multi-component gases. In actual ammonia energy equipment, gaseous ammonia often coexists with multiple gases such as air, oxygen, and water vapor. Accurate simulation of gas components is crucial for assessing material corrosion behavior. Secondly, it lacks an active circulation mixing mechanism: the device relies on the nozzle structure to improve the initial gas distribution, but it lacks a gas circulation system, making it impossible to avoid stratification caused by gas density differences during long-term testing. This is especially problematic during alternating high and low temperatures or prolonged static testing, where maintaining gas uniformity is difficult. Thirdly, the temperature control range is limited and lacks flexibility. The device does not clearly define the specific design and range of its temperature control system, while materials in ammonia energy equipment may face extreme temperature ranges from low-temperature storage and transportation (e.g., -35℃) to high-temperature combustion (e.g., 800℃). Most existing testing devices can only cover a narrow temperature range and cannot achieve high-precision simulation over a wide temperature range. Fourthly, the test environment lacks sufficient sealing. The device is an open or semi-closed test chamber, making it difficult to completely isolate external air. For corrosion tests requiring strict control of gas composition (e.g., an oxygen-free environment), its sealing performance may not meet the requirements.

[0006] Therefore, there is an urgent need to develop a gaseous ammonia testing device that can achieve precise gas component ratio, has active circulation mixing function, covers a wide temperature range, and has good sealing performance, so as to more realistically simulate the service behavior of materials in complex gaseous ammonia environments. This device will provide reliable technical means for material selection, life prediction, and safety assessment of key equipment such as ammonia-powered engines and large liquid ammonia storage tanks, thereby promoting the safe and efficient development of the ammonia energy industry. Summary of the Invention

[0007] In view of this, the present invention aims to propose a gaseous ammonia corrosion test device with circulation function to solve the problems in the prior art that the test device cannot accurately prepare and determine complex gas components, it is difficult to truly simulate the gaseous ammonia mixing environment, the gas uniformity cannot be guaranteed in long-term tests, and the temperature control range is limited and cannot cover actual service conditions.

[0008] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0009] This invention discloses a gaseous ammonia corrosion testing device with a circulation function, comprising:

[0010] The test vessel includes a vessel body and a lid that can be sealed together;

[0011] A gas composition control system includes at least one gas inlet on the test vessel and a gas flow control device connected to the gas inlet for precisely controlling the gas input ratio.

[0012] The gas circulation system includes a gas circulation pipeline installed on the test vessel and a circulation pump that drives the gas to circulate between the gas circulation pipeline and the internal space of the test vessel.

[0013] The temperature control system is configured to be movable relative to the vessel body to enable connection or separation between the temperature control system and the vessel body; and the gaseous ammonia corrosion test device can be adapted to different test temperature ranges by switching the temperature control system.

[0014] The automated drive design of the vessel lid lifting rod reduces manual operation intensity and avoids misalignment of the sealing surface caused by manual fitting. The movable and switchable design of the temperature control system allows a single test device to flexibly cover an extreme wide temperature range from cryogenic to high temperature, solving the core problem of narrow temperature control range and inability to simulate real service conditions in traditional equipment. The establishment of the gas circulation system realizes the flow path design of test gas injection-circulation-discharge, effectively breaking the stratification phenomenon that may be caused by gas density differences or long-term static placement, ensuring the high uniformity of gas composition in time and space during the test, thereby significantly improving the accuracy and reliability of corrosion test results. Furthermore, the temperature control system includes a first temperature control system and a second temperature control system; the first temperature control system is connected or separated from the vessel body through a lifting structure, and the second temperature control system is connected or separated from the vessel body through a horizontal moving structure.

[0015] The test apparatus of this invention solves the technical problem that a single test apparatus cannot cover an extreme wide temperature range from ultra-low temperature to ultra-high temperature through a switchable dual temperature control system design.

[0016] Furthermore, the lifting structure includes a vertically movable first temperature control system lifting rod and a first temperature control system base plate connected to the first temperature control system lifting rod, with the first temperature control system mounted on the first temperature control system base plate; the horizontal moving structure includes a second temperature control system horizontal slide connected to the device support column, and an electric heating sleeve latch mounted on the second temperature control system.

[0017] The differentiated design of the lifting structure and the horizontal moving structure ensures a close fit and rapid switching between the two temperature control systems and the vessel body, significantly improving the efficiency of experimental operations. Furthermore, the first temperature control system includes a circulating oil bath coil connected to an external oil bath machine; the second temperature control system includes an electric heating layer connected to an external temperature controller; and both the first and second temperature control systems include a metal heat-conducting layer that can adhere to the outer wall of the vessel body.

[0018] The combined design of the metal heat-conducting layer and the insulation layer ensures both uniform and efficient temperature transfer while reducing energy loss, thus significantly improving temperature control accuracy. Furthermore, the differentiated heating / cooling methods of the electric heating layer and the circulating oil bath coil respectively meet the needs of rapid high-temperature heating and stable low-temperature control, further enhancing the temperature control flexibility and reliability of the experimental device of this invention.

[0019] Furthermore, the lid is sealed to the vessel body via a lid lifting rod and fixing bolts; and the test vessel is equipped with an air inlet and an exhaust outlet.

[0020] The tight seal between the vessel body and the lid effectively prevents external air from entering, ensuring the purity of the test gas components; the design of the air inlet and outlet facilitates the precise injection of test gas and the safe discharge of waste gas after the test.

[0021] Furthermore, the gas circulation pipeline includes a gas circulation coil installed on the test vessel, and multiple ventilation units are provided on the gas circulation coil.

[0022] By introducing ventilation units on the gas circulation coil, gas diffusion is promoted, the gas circulation coverage is expanded, and the gas is more evenly diffused to all areas inside the test vessel, effectively preventing gas stratification inside the vessel.

[0023] Furthermore, the gas circulation coil also includes an upper coil and a lower coil installed on the test vessel, and the upper coil and the lower coil are connected to the circulation pump through a gas circulation coil connecting pipe.

[0024] The upper and lower coils form a three-dimensional circulation loop, driving the gas to circulate vertically within the reactor, further eliminating gas stagnation areas and ensuring the uniformity of components throughout the reactor space.

[0025] Furthermore, the ventilation units are distributed circumferentially along the gas circulation coil and are inclined relative to the gas circulation coil; the ventilation units are located in the upper and lower coils respectively.

[0026] The circumferential distribution ensures that the airflow covers all areas without dead zones, the inclined setting avoids the airflow directly hitting the sample, and the corresponding positions above and below can form directional convection, which greatly improves the gas mixing efficiency.

[0027] Furthermore, each ventilation unit includes at least one ventilation port; and the angle between the central axis L1 and the central axis L2 of each ventilation port is α.

[0028] By controlling the tilt angle α of the vent, the airflow direction can be precisely guided, the vortex effect can be optimized, and efficient mixing can be achieved while minimizing interference with the surface condition of the sample.

[0029] Furthermore, the test vessel is equipped with a sample holder, which includes a sample support rod and positioning pins; and the positioning pins are evenly spaced along the sample support rod.

[0030] The specimen holder enables the orderly and standardized fixation of specimens, ensuring consistent spacing and equal exposure conditions for each specimen, thereby improving the comparability and accuracy of parallel test data.

[0031] Compared with existing technologies, the ammonia corrosion testing device with circulation function described in this invention has the following advantages:

[0032] (1) The simulation of working conditions is highly realistic: Through the coordinated design of a high-sealing test vessel, a precise gas component control system and an active circulation system, it can accurately reproduce the mixed environment of ammonia with air, oxygen and other components, while avoiding gas stratification in long-term tests and fully conforming to the gas environment characteristics of the material in actual service.

[0033] (2) Wide temperature control coverage and efficient switching: The dual temperature control system achieves wide-range temperature regulation and maintains excellent temperature uniformity and stability, adapting to different working conditions such as low-temperature storage and transportation and high-temperature combustion; the lifting and horizontal moving structure allows for quick switching between the two temperature control systems without disassembling core components, making operation convenient and temperature control precise.

[0034] (3) Stable and reliable test results: The specially designed ventilation unit structure, combined with the upper and lower double circulation coils, not only avoids the airflow directly impacting the sample, but also eliminates the gas stagnation at the corners of the test vessel. Combined with the orderly arranged sample holder, it ensures that the environment of multiple samples is consistent, greatly improving the repeatability and accuracy of the test results.

[0035] (4) Strong structural adaptability and practicality: The sealing performance of the test vessel meets the stringent vacuum requirements and effectively isolates external interference; the overall structure of the sample holder takes into account both long-term test stability and operational safety, and adapts to diverse testing needs. Attached Figure Description

[0036] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1This is a schematic diagram of the structure of the ammonia corrosion testing device described in this invention;

[0038] Figure 2 This is a schematic diagram of the structure of the test vessel described in this invention;

[0039] Figure 3 This is a schematic diagram of the gas circulation coil described in this invention;

[0040] Figure 4 This is a schematic cross-sectional view of the ventilation unit described in this invention on the gas circulation coil;

[0041] Figure 5 This is a schematic diagram of the sample holder structure described in this invention;

[0042] Figure 6 This is a cross-sectional view of the test vessel described in this invention.

[0043] Explanation of reference numerals in the attached figures:

[0044] 1. Test vessel; 11. Vessel body; 12. Vessel lid; 13. Vessel lid lifting rod; 14. Fixing bolt; 15. Air inlet; 16. Exhaust outlet; 17. Gas circulation coil; 171. Upper coil; 172. Lower coil; 173. Ventilation unit; 1731. Ventilation port; 174. Gas circulation coil connecting pipe; 18. Sample holder; 181. Sample bearing rod; 182. Positioning pin; 183. Sample; 2. Device base; 3. Device support column; 4. First temperature control system; 41. First temperature control system lifting rod; 42. First temperature control system base plate; 43. Circulating oil bath coil; 5. Second temperature control system; 51. Electric heating jacket lock; 52. Second temperature control system horizontal slide; 6. Circulation pump. Detailed Implementation

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In addition, the orientations involved in the following specific embodiments are briefly explained: the directions or positional relationships indicated by "front", "rear", "up", "down", "left", "right", "top", "bottom", etc. mentioned in the embodiments refer to the orientations or positional relationships shown in the accompanying drawings, and the term "on" means directly or indirectly supported by the element.

[0046] It should be noted that, in the description of this invention, 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, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0047] This invention provides a gaseous ammonia corrosion testing device with a circulation function, comprising:

[0048] Test vessel 1, which includes a vessel body 11 and a vessel lid 12 that can be sealed together;

[0049] A gas composition control system includes at least one air inlet 15 disposed on the test vessel 1, and a gas flow control device connected to the air inlet 15 for precisely controlling the gas input ratio.

[0050] The gas circulation system includes a gas circulation pipeline installed on the test vessel 1, and a circulation pump 6 that drives the gas to circulate between the gas circulation pipeline and the internal space of the test vessel 1.

[0051] The temperature control system is configured to be movable relative to the vessel body 11 to enable connection or separation between the temperature control system and the vessel body 11; and the gaseous ammonia corrosion test device can be adapted to different test temperature ranges by switching the temperature control system.

[0052] More specifically, the ammonia corrosion testing apparatus also includes a base 2 and a support column 3. The support column 3 is vertically fixed to the base 2 and supports the test vessel 1 and other components, forming a stable frame for the ammonia corrosion testing apparatus. The vessel lid 12 is sealed to the vessel body 11 via a lid lifting rod 13 and fixing bolts 14. The test vessel 1 is equipped with an air inlet 15 and an exhaust outlet 16. The fixing bolts 14 are evenly distributed around the lid 12 to ensure balanced force on the sealing surfaces of the lid 12 and the vessel body 11. The lid lifting rod 13 is driven by a motor and can precisely adjust the lifting stroke of the lid 12 to achieve tight contact or rapid separation with the vessel body 11. After the lid lifting rod 13 drives the lid 12 to complete the lifting action, the multiple fixing bolts 14 arranged circumferentially are tightened manually or with tools to apply sufficient sealing surface pressure. The vessel body 11 of the test vessel 1 is integrally formed from high-strength corrosion-resistant material, with no obvious protrusions or dead corners in the internal cavity, reducing gas flow resistance. The air inlet 15 is equipped with an adjustable control valve, which is connected to a gas flow control device via a pipeline for receiving multi-component test gases, such as oxygen and air, supplied by the gas composition control system; the exhaust port 16 is equipped with an adjustable control valve, which is connected to a vacuum pump or exhaust gas treatment system for establishing a vacuum environment before the test or for safely discharging exhaust gas after the test; the gas circulation pipeline is symmetrically arranged inside the test vessel 1 and connected to the external circulation pump 6 to form a gas circulation loop.

[0053] It should be noted that a sealing gasket or a metal surface seal is usually provided between the lid 12 and the vessel body 11 to ensure sealing reliability during high-pressure, high-vacuum, or long-term testing. The core design logic of the test vessel 1 is to provide a highly sealed, low-interference, and easy-to-operate carrying space for simulating complex ammonia gas environments. Its sealing structure must meet the stringent requirement of vacuuming to ≤0.1Pa to prevent external air from interfering with the test gas components. The movable nature of the temperature control system allows it to be selected and switched according to the temperature range required for the test. After determining the temperature control system, it is moved to fit tightly against the outer wall of the vessel body 11, thereby achieving efficient and uniform temperature control inside the test vessel 1. When a new temperature control system needs to be replaced, it is removed and the new temperature control system is moved to fit tightly against the outer wall of the vessel body 11.

[0054] The automated drive design of the lid lifting rod 13 reduces the intensity of manual operation and avoids misalignment of the sealing surface caused by manual fitting. The circumferentially evenly distributed fixing bolts 14 ensure consistent pressure on the sealing surface, preventing localized leakage. The combined design of the lid lifting rod 13 and fixing bolts 14 enables convenient opening and closing of the test vessel 1 and reliable sealing, laying the structural foundation for creating and maintaining a pure and controllable gas testing environment. It also avoids component fluctuations caused by gas backflow. The movable and switchable design of the temperature control system allows a single test device to flexibly cover an extreme wide temperature range from cryogenic to high temperature, solving the core problem of narrow temperature control range and inability to simulate real service conditions in traditional equipment. The establishment of the gas circulation system realizes a flow path design of test gas injection-circulation-discharge, effectively breaking the stratification phenomenon that may be caused by gas density differences or long-term static storage, ensuring high uniformity of gas components in time and space during the test, thereby significantly improving the accuracy and reliability of corrosion test results.

[0055] Specifically, the temperature control system includes a first temperature control system 4 and a second temperature control system 5; and the first temperature control system 4 is connected to or separated from the vessel body 11 through a lifting structure, and the second temperature control system 5 is connected to or separated from the vessel body 11 through a horizontal moving structure. More specifically, the lifting structure includes a vertically movable first temperature control system lifting rod 41 and a first temperature control system base plate 42 connected to the first temperature control system lifting rod 41. The first temperature control system 4 is mounted on the first temperature control system base plate 42. The horizontal moving structure includes a second temperature control system horizontal slide rail 52 connected to the device support column 3, and an electric heating sleeve lock 51 mounted on the second temperature control system 5. The first temperature control system 4 includes a circulating oil bath coil 43, which is connected to an external oil bath machine. The second temperature control system 5 includes an electric heating layer, which is connected to an external temperature controller. Both the first temperature control system 4 and the second temperature control system 5 include a metal heat-conducting layer that can adhere to the outer wall of the vessel body 11. The first temperature control system 4 also has an insulation layer wrapped around the outside of the circulating oil bath coil 43, and the second temperature control system 5 also has an insulation layer wrapped around the outside of the electric heating layer. It should be noted that the metal heat-conducting layer, as the direct contact interface with the vessel body 11, ensures that heat or cold energy can be efficiently and evenly transferred to the entire vessel body 11. The second temperature control system 5 is a high-temperature temperature control system, in which the electric heating layer is a uniformly wound resistance wire. Heating of the vessel body 11 is achieved by energizing the resistance wire within the electric heating layer, and it is suitable for a temperature range of 200℃ to 800℃. The metal heat-conducting layer is made of a material with high thermal conductivity to ensure efficient heat / cold energy conduction. The first temperature control system 4 is a low-temperature temperature control system, which absorbs heat through the low-temperature heat-conducting oil circulating in the circulating oil bath coil 43 to achieve cooling or low-temperature constant temperature control of the vessel body 11, and is suitable for a temperature range of -35℃ to 200℃. During the experiment, the corresponding temperature control system is selected and activated according to the target temperature. When the first temperature control system 4 is activated, the lifting structure drives the first temperature control system base plate 42 via a motor, causing it to support the low-temperature control system 4 and move upward along the first temperature control system lifting rod 41 until the inner layer of the first temperature control system 4 is completely in contact with the outer wall of the vessel body 11, ensuring heat transfer efficiency. When the second temperature control system 5 is activated, the horizontal moving structure pushes the second temperature control system 5 laterally via the second temperature control system horizontal slide 52. When the second temperature control system 5 moves upward along the first temperature control system lifting rod 41, the lifting structure moves upward along the first temperature control system lifting rod 41 until the inner layer of the first temperature control system 4 is completely in contact with the outer wall of the vessel body 11, ensuring heat transfer efficiency. After the horizontal slide 52 of the second temperature control system slides to the working position, the electric heating jacket lock 51 is operated to mechanically interlock with the preset positioning slot on the horizontal slide 52 of the second temperature control system or with the preset structure of the second temperature control system 5 itself, thereby preventing it from accidentally shifting due to vibration or thermal expansion during the test. The working position refers to the position where the metal heat-conducting layer of the second temperature control system 5 is completely and tightly fitted with the outer wall of the vessel body 11 of the test vessel 1 after the second temperature control system 5 moves through the horizontal slide 52 of the second temperature control system, so that heat conduction can be effectively carried out.Switching between the two temperature control systems does not require disassembling the core components of the test vessel 1; it can be accomplished simply by adjusting the corresponding moving structure. This operation is convenient and does not affect the sealing performance of the test vessel 1. Since the first temperature control system 4 is a low-temperature system, and it includes a circulating oil bath coil and external piping, its overall weight is relatively large, and reliable piping connections must be ensured. The lifting structure provides stable and uniform support and lift from below, allowing the entire low-temperature temperature control system to rise smoothly and fit snugly against the vessel body 11, avoiding poor fit or structural stress caused by weight imbalance. The second temperature control system 5 mainly consists of an electric heating layer and an insulation layer. Its structure is relatively compact, and the horizontal moving structure facilitates quick insertion and removal. Furthermore, the high-temperature temperature control system generates a large amount of radiant heat during operation; the horizontal moving structure allows it to quickly separate from the vessel body 11, facilitating heat dissipation and maintenance. It also keeps the system away from the circulating pump 6 and piping during operation, effectively avoiding the safety risks associated with lifting operations on high-temperature components.

[0056] The experimental apparatus of this invention solves the technical challenge of a single experimental apparatus being unable to cover an extreme wide temperature range from ultra-low to ultra-high temperatures through a switchable dual temperature control system design. The differentiated design of the lifting structure and the horizontal moving structure ensures close contact and rapid switching between the two temperature control systems and the vessel body 11, significantly improving experimental efficiency. The combined design of the metal heat-conducting layer and the insulation layer ensures both uniform and efficient temperature transfer while reducing energy loss, greatly improving temperature control accuracy. Furthermore, the differentiated heating / cooling methods of the electric heating layer and the circulating oil bath coil 43 respectively meet the needs of rapid high-temperature heating and stable low-temperature control, further enhancing the temperature control flexibility and reliability of the experimental apparatus of this invention.

[0057] Specifically, the gas circulation pipeline includes a gas circulation coil 17 installed on the test vessel 1, and multiple ventilation units 173 are provided on the gas circulation coil 17.

[0058] More specifically, the gas circulation coil 17 also includes an upper coil 171 and a lower coil 172 installed on the test vessel 1. The upper coil 171 and the lower coil 172 are connected to the circulation pump 6 through a gas circulation coil connecting pipe 174. The upper coil 171 and the lower coil 172 are symmetrically and horizontally arranged in the upper and lower areas inside the test vessel 1, forming a spiral structure that maximizes the coverage of the internal cross-sectional area of ​​the test vessel 1. The gas circulation coil connecting pipe 174 is sealed to the inlet and outlet of the circulation pump 6, forming a closed loop of "upper coil 171 - gas circulation coil connecting pipe 174 - circulation pump 6 - lower coil 172 - inside the test vessel 1 - upper coil 171". The circulation pump 6 is driven by a motor and can be set to a timed operation mode.

[0059] It should be noted that the ventilation units 173 are distributed circumferentially along the gas circulation coil 17 and are inclined relative to the gas circulation coil 17; the distribution positions of the ventilation units 173 on the upper coil 171 and the lower coil 172 correspond one-to-one. The gas circulation coil 17 has a spiral structure, and the ventilation units 173 are arranged circumferentially along its circumference, which can cover the entire circumference inside the test vessel 1. This avoids the formation of gas stagnation zones near the corners and side walls of the test vessel 1 due to the ventilation units being concentrated in a single location, ensuring that gas at any location inside the vessel can participate in circulation, thus guaranteeing the uniformity of gas composition in space; the inclined arrangement of the ventilation units 173 relative to the gas circulation coil 17 is primarily to avoid the airflow directly impacting the sample 183; if the ventilation units 173 were vertically opened on the gas circulation coil 17, the airflow would directly hit the surface of the sample 183, which may damage the surface condition of the sample 183 or cause abnormal local corrosion environment, affecting the authenticity of the test; at the same time, the inclined airflow can diffuse to the surroundings, rather than being concentrated and sprayed. This design promotes rapid fusion of gases from different regions, reducing the risk of stratification, and is particularly suitable for mixed gases with significant density differences, such as ammonia and air / oxygen. Furthermore, the ventilation units 173 of the upper coil 171 and lower coil 172 are positioned in a one-to-one correspondence, forming a vertical "suction-jet" convection channel. The ventilation unit 173 at the corresponding position of the upper coil 171 draws in gas from the upper part, while the corresponding ventilation unit 173 at the lower part jets gas, creating directional convection and accelerating gas exchange between the upper and lower parts. This completely breaks down gas stratification caused by density differences, ensuring consistent gas composition and temperature throughout the entire vessel. When the circulation pump 6 starts, it draws in gas from the upper part of the vessel body 11. The gas first enters the upper coil 171 through the ventilation unit 173, then is transported to the circulation pump 6 through the gas circulation coil connecting pipe 174. After being pressurized, it is then transported to the lower coil 172 through the gas circulation coil connecting pipe 174, and finally injected into the lower space of the vessel body 11 from its ventilation unit 173.

[0060] The gas circulation system in the experimental apparatus of this invention uses a circulation pump 6 to force continuous gas flow within the vessel, effectively solving the problem of component stratification caused by differences in gas density during long-term testing. The symmetrical distribution of the upper coil 171 and the lower coil 172 enables forced convection of gas between the upper and lower regions within the vessel. The spiral structure ensures that gas circulation covers all lateral positions inside the experimental vessel 1, avoiding circulation blind spots. The closed-loop design effectively prevents gas leakage and ensures the airtightness of the experimental environment. The timed operation mode of the circulation pump 6 can maintain gas uniformity without interfering with the testing state of the sample 183, while reducing energy consumption.

[0061] Specifically, each ventilation unit 173 includes at least one ventilation port 1731; and the angle between the central axis L1 and the central axis L2 of each ventilation port 1731 is α.

[0062] More specifically, L1 is the central axis of the vent 1731 itself, that is, the central flow line of the airflow through the vent 1731; the direction perpendicular to the plane where the gas circulation coil 17 is located is denoted as radial, and L2 is the central axis extending radially outward from the center of the gas circulation coil 17, that is, the radial central axis of the gas circulation coil 17. The vent 1731 of the upper coil 171 is located on the upper part of its pipe wall and is obliquely upward, while the corresponding vent 1731 on the lower coil 172 is located on the lower part of its pipe wall and is obliquely downward.

[0063] It should be noted that the central axis L1 of the vent 1731 forms an angle α with the central axis L2 of the gas circulation coil 17. This angle α is an acute angle. This angle design, combined with the tilt direction, ensures that the direction of the ejected or drawn-in airflow forms a specific angle with the central axis L2 of the coil, rather than being ejected or drawn in perpendicularly. This allows the ejected or drawn-in airflow during circulation to avoid the area where the sample support 18 is located in the middle of the test vessel 1, and to avoid directly impacting the sample 183. When the circulation pump 6 is working, the upward-sloping vent 1731 of the upper coil 171 mainly acts to draw gas from the upper part of the vessel body 11, while the downward-sloping vent 1731 of the lower coil 172 mainly injects gas into the lower part of the vessel body 11. This inclined airflow, corresponding to each other and in opposite directions, can form an orderly three-dimensional circulating vortex inside the vessel, promoting sufficient exchange of gas between the upper and lower layers and in the corner areas.

[0064] Preferably, the angle α between the central axis L1 of the vent 1731 and the central axis L2 of the gas circulation coil 17 is 45°. This angle ensures effective mixing while minimizing the interference of the airflow directly hitting the surface of the sample 183 and thus preventing interference with the natural corrosion process. Furthermore, along the circumference of the gas circulation coil 17, a venting unit 173 can be installed at regular intervals. Each venting unit 173 contains two vents 1731, with a 90° angle between the central axes L1 of the two vents 1731, thus forming a cross-complementary airflow pattern to further optimize the mixing effect.

[0065] The inclined design of the vent 1731, with its upper part angled upwards and the lower part angled downwards, combined with an acute angle α, allows the airflow to precisely avoid the area where the sample holder 18 is located, preventing direct impact on the surface of the sample 183. This ensures that the corrosion process closely matches the natural working conditions of the material during actual service, without interfering with the test process. This significantly improves the realism of the simulated environment and the reliability of the test results. Furthermore, the upward suction from the upper coil 171 vent 1731 and the downward spray from the lower coil 172 corresponding to the lower coil 1731 vent 1731, with their corresponding upper and lower parts and opposite directions, creates an orderly three-dimensional circulating vortex within the test vessel 1. This effectively promotes the full exchange of gas between the upper and lower layers and in the corner areas of the test vessel 1, fundamentally solving the stratification problem that may occur due to differences in gas density or long-term static storage, and ensuring a high degree of uniformity in gas composition, concentration, and temperature within the test vessel 1.

[0066] Specifically, the test vessel 1 is equipped with a sample support 18, which includes a sample support rod 181 and a positioning pin 182; and the positioning pins 182 are evenly distributed along the sample support rod 181.

[0067] It should be noted that the sample support rod 181 is a horizontally arranged crossbar structure, and the positioning pins 182 extend upward perpendicular to the sample support rod 181 and are distributed at fixed intervals along the length of the sample support rod 181. They are used to separate and position the samples 183, ensuring that multiple samples 183 maintain a constant distance during the test, avoiding mutual contact that could cause galvanic interference or shielding effect, and ensuring that the corrosive medium can flow freely around the samples 183. In addition, the samples 183 maintain a safe distance from the inner wall of the test vessel 1 and the gas circulation coil 17.

[0068] The structural design of the sample holder 18 enables standardized and orderly fixation and arrangement of the samples 183. The precise spacing of the positioning pins 182 ensures consistent exposure conditions for all samples 183 in the corrosive environment, eliminating localized airflow or concentration differences caused by improper spacing of the samples 183, thereby improving the comparability and reliability of parallel test data. Furthermore, the structural design of the sample holder 18 is compatible with various sample 183 fixation methods, significantly enhancing the adaptability of the testing device to different testing requirements and demonstrating excellent versatility and operability.

[0069] Example 1

[0070] like Figures 1 to 5 As shown, this embodiment provides a gaseous ammonia corrosion testing device with a circulation function, used to simulate the storage and transportation conditions of a large liquid ammonia storage tank in a low-temperature oxygen-containing ammonia environment (-20℃), and to test the stainless steel inner liner material of the large liquid ammonia storage tank under this environment. The specific steps are as follows:

[0071] Preparation and pretreatment of S1 specimen 183: Three standard specimens 110mm × 20mm × 3mm in size were cut from 10mm thick 304 stainless steel plates used in large liquid ammonia storage tanks, along the deformation direction of the 304 stainless steel plate surface. Before the test, all specimens 183 were uniformly treated: they were marked, their dimensions were measured, and they were cleaned in sequence. A four-point bending fixture was used to apply stress to the three specimens 183 to simulate the stress state of the tank material during storage and transportation. The loading results of the four-point bending fixture on each specimen 183 include the elastic modulus of stainless steel, the loaded load, and the deflection of the specimen after loading, as shown in Table 1. The distance between the outer support points of the four-point bending fixture was 100mm, and the distance between the inner and outer support points was 25mm.

[0072] Table 1 Sample loading results

[0073]

[0074] S2 Test Apparatus Assembly and Sealing: After loading, the sample 183 is clamped on the four-point bending fixture. The four-point bending fixture passes through the sample support rod 181 of the sample holder 18 through the reserved hole, and the position of the sample 183 is fixed by the evenly distributed positioning pins 182 on the sample holder 18, ensuring that the three samples 183 do not contact each other and are spaced at a certain distance to avoid mutual interference between the samples 183 during the test. The lid 12 is driven by the motor to move downward along the lid lifting rod 13, so that the lid 12 is tightly fitted with the end face of the body 11. Then, the six fixing bolts 14 evenly arranged around the lid 12 are tightened to achieve the sealing of the test vessel 1.

[0075] S3 First Temperature Control System 4 Installation and Debugging: Select the temperature control system according to the test temperature. If the test temperature is -35℃ to 200℃, select the first temperature control system 4 for temperature control. In this embodiment, the test temperature is -20℃. Therefore, start the motor to control the base plate 42 of the first temperature control system to support the low temperature control system 4 and move it upward along the lifting rod 41 of the first temperature control system until the inner layer of the first temperature control system 4 is completely in contact with the outer wall of the vessel 11 to ensure heat transfer efficiency. The first temperature control system 4 includes a three-layer structure. The inner layer is a metal heat-conducting layer that is tightly in contact with the outer wall of the vessel 11 to achieve efficient and uniform heat conduction. The middle layer is a circulating oil bath coil 43 that is spirally wound around the metal heat-conducting layer and is connected to an external oil bath machine. The outer layer is an insulation layer wrapped around the outside of the circulating oil bath coil 43 to minimize cold loss. During operation, the oil bath machine continuously pumps low-temperature heat transfer oil into the circulating oil bath coil 43. By controlling the temperature and flow rate of the heat transfer oil, precise and stable temperature control can be achieved in the test vessel 1.

[0076] S4 Test Apparatus Vacuuming Procedure: Open the control valve on the inlet 15 and close the control valve on the outlet 16. Connect the vacuum pump to the inlet 15 via a dedicated pipeline and start the vacuum pump to evacuate the interior of the test vessel 11 and related gas pipelines. Monitor the vacuum level in real time. When the vacuum level is ≤0.1Pa, close the control valves of the vacuum pump and the inlet 15 to complete the vacuuming operation and avoid residual air interfering with the test gas components.

[0077] S5 Test Gas Precision Proportioning and Injection: Based on the actual storage and transportation environment of the large liquid ammonia storage tank, the composition and corresponding volume fraction of the test gas were set as 99.0% ammonia + 1.0% oxygen. Two high-precision gas mass flow meters of the test component control system were used to control the gas source output of ammonia and oxygen respectively. According to the volume flow ratio under standard conditions, the two gases were sequentially injected into the vessel body 11 through inlet 15. After injection, the control valve on inlet 15 was closed, and the mixture was allowed to stand for at least 20 minutes to allow the injected gases to initially mix naturally within the vessel body 11.

[0078] S6 Temperature Regulation and Stability Control: Start the external low-temperature oil bath machine and set the target temperature to -20℃. The oil bath machine delivers low-temperature heat transfer oil to the circulating oil bath coil 43 through the circulating pump 6. The cold energy is transferred to the inside of the vessel 11 through the inner metal heat transfer layer. After the temperature stabilizes at -20℃, obtain the pressure value inside the test vessel 1 and increase the volume of impurity gas and ammonia gas proportionally until the pressure is displayed as 0Pa. Then continue to run the oil bath machine. After the temperature stabilizes again and the pressure does not fluctuate, start recording the test time.

[0079] S7 Gas Circulation System Operation: To prevent component stratification due to gas density differences during the experiment, the circulation pump 6 is started daily for 1 hour. The circulation pump 6 draws gas from the upper part of the vessel 11 through the venting unit 173 of the upper coil 171 via the gas circulation coil connection pipe 174. After being pressurized by the circulation pump 6, the gas is transported to the lower coil 172, and then returned to the lower part of the vessel 11 through the venting unit 173 on the lower coil 172, forming a closed circulation loop. The structural design of the gas circulation coil 17 avoids direct airflow impact on the sample 183, while ensuring that the gas in the corner areas of the vessel 11 participates in circulation, maintaining the uniformity of gas composition throughout the vessel.

[0080] S8 test completion and sample 183 testing: After 30 days of continuous testing, first turn off the low-temperature oil bath machine and circulation pump 6. After the temperature inside the vessel 11 naturally rises to room temperature, slowly open the control valve of the exhaust port 16 to slowly release the gas inside the vessel 11. After the pressure inside the vessel 11 drops to normal pressure, loosen the fixing bolts 14, lift the vessel lid 12 through the lid lifting rod 13, take out the sample 183, and conduct a comprehensive test on the sample 183.

[0081] The test results showed that there were no visible cracks on the outer surface of all 183 bent samples, indicating that 304 stainless steel has good stress corrosion resistance in this low temperature, low oxygen and ammonia-containing environment, which can meet the storage and transportation service requirements of large liquid ammonia storage tanks.

[0082] Example 2

[0083] like Figures 1 to 5 As shown, this embodiment provides a gaseous ammonia corrosion testing device with a circulation function, used to simulate the operating conditions near the combustion chamber of an ammonia-powered engine in a high-oxygen-content gaseous ammonia environment (300℃), and to test the high-temperature alloy materials used in the combustion chamber of the ammonia-powered engine under this environment. The specific steps are as follows:

[0084] Preparation and pretreatment of S1 specimen 183: Select a 20mm thick 2205 duplex stainless steel plate welded joint, and cut three specimens 183 with dimensions of 50mm×20mm×20mm perpendicular to the weld direction on the welded joint to ensure that the weld is located in the center of the specimen and retain the original weld reinforcement, simulating the actual state of the welded structure of the combustion chamber of an ammonia-powered engine; then perform surface treatment on specimen 183.

[0085] S2 test apparatus assembly and sealing: The treated sample 183 is suspended on the sample support rod 181 of the sample holder 18 using a corrosion-resistant stainless steel wire. The spacing of the sample 183 is adjusted by the positioning pin 182 to ensure smooth gas flow around the sample 183. Then, the test vessel 1 is sealed according to the sealing steps of the test vessel 1 in Example 1.

[0086] Installation and Debugging of the Second Temperature Control System 5 (S3): In this embodiment, the test temperature is 300℃, therefore, the second temperature control system 5 is selected for temperature control. Open the electric heating jacket latch 51 and push the second temperature control system 5 along the horizontal slide 52 to the outside of the vessel body 11, ensuring the inner layer of the second temperature control system 5 is tightly fitted to the outer wall of the vessel body 11. The second temperature control system 5 also adopts a three-layer structure: the inner layer is a metal heat-conducting layer tightly fitted to the outer wall of the vessel body 11, used to achieve efficient and uniform heat conduction; the middle layer is a uniformly wound resistance wire; and the outer layer is an insulating layer wrapped around the resistance wire, used to minimize heat loss. During operation, the heating power of the resistance wire is adjusted by the temperature controller to achieve precise and stable temperature control within the test vessel 1.

[0087] S4 Vacuum treatment of the test apparatus: Same as step S4 in Example 1.

[0088] S5 Test Gas Precision Proportioning and Injection: Based on the high-temperature, oxygen-rich ammonia-gas mixture environment near the combustion chamber of the ammonia-powered engine, the composition and corresponding volume fraction of the test gas were set to 10% ammonia + 90% oxygen. Other steps were the same as in Example 1.

[0089] S6 Temperature Regulation and Stabilization Control: Start the temperature controller of the second temperature control system 5 and set the target temperature to 300℃. The resistance wire is energized and heats up. The heat is transferred to the inside of the vessel 11 through the inner metal heat-conducting layer. After the temperature stabilizes at 300℃, obtain the pressure value inside the test vessel 1, and increase the volume of impurity gas and ammonia gas proportionally until the pressure display shows 0Pa. Then continue to run the second temperature control system 5. After the temperature stabilizes again and the pressure is stable, start recording the test time.

[0090] S7 Gas circulation system operation: Same as step S7 in Example 1.

[0091] S8 test ends and sample 183 is tested: the same as step S8 in Example 1.

[0092] The test results showed that no cracks were found in the weld, weld toe, heat-affected zone, and base material area on sample 183. Metallographic samples were taken from the weld, weld toe, heat-affected zone, and base material area on sample 183, and the cross-sections were ground and polished without etching. No stress corrosion cracks were found in the above-mentioned parts. This indicates that the 2205 duplex stainless steel welded joint has excellent corrosion resistance in the high oxygen content ammonia high temperature environment and can meet the service requirements of the combustion chamber of ammonia-powered engine.

[0093] In summary, the ammonia corrosion testing device of the present invention, through the synergistic effect of the high sealing design of the test vessel 1, the precise proportioning system of the test components, the efficient gas circulation mechanism, and the wide-range adjustable temperature control system, achieves realistic simulation of both single ammonia environments and complex mixed gas environments such as ammonia with air and oxygen. It effectively solves the technical bottlenecks of difficulty in accurately simulating complex ammonia environments, the long-term inability to guarantee gas uniformity, and the narrow temperature range, providing reliable and efficient testing technology support for the material development, performance evaluation, and safety selection of key ammonia energy equipment.

[0094] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A gaseous ammonia corrosion testing device with circulation function, characterized in that, The ammonia corrosion testing device includes: Test vessel (1), the test vessel (1) includes a vessel body (11) and a vessel lid (12) that can be sealed together. A gas composition control system, comprising at least one air inlet (15) disposed on the test vessel (1), and a gas flow control device connected to the air inlet (15) for precisely controlling the gas input ratio; The gas circulation system includes a gas circulation pipeline installed on the test vessel (1) and a circulation pump (6) that drives the gas to circulate between the gas circulation pipeline and the internal space of the test vessel (1). The temperature control system is configured to be movable relative to the vessel body (11) to achieve connection or separation between the temperature control system and the vessel body (11); and the gaseous ammonia corrosion test device can adapt to different test temperature ranges by switching the temperature control system.

2. The ammonia corrosion testing apparatus according to claim 1, characterized in that, The temperature control system includes a first temperature control system (4) and a second temperature control system (5); the first temperature control system (4) is connected to or separated from the vessel body (11) through a lifting structure, and the second temperature control system (5) is connected to or separated from the vessel body (11) through a horizontal moving structure.

3. The ammonia corrosion testing apparatus according to claim 2, characterized in that, The lifting structure includes a vertically movable first temperature control system lifting rod (41) and a first temperature control system base plate (42) connected to the first temperature control system lifting rod (41), with the first temperature control system (4) mounted on the first temperature control system base plate (42); the horizontal moving structure includes a second temperature control system horizontal slide (52) connected to the device support column (3) and an electric heating sleeve latch (51) mounted on the second temperature control system (5).

4. The ammonia corrosion testing apparatus according to claim 2, characterized in that, The first temperature control system (4) includes a circulating oil bath coil (43), which is connected to an external oil bath machine; the second temperature control system (5) includes an electric heating layer, which is connected to an external temperature controller; and both the first temperature control system (4) and the second temperature control system (5) include a metal heat-conducting layer that can be attached to the outer wall of the vessel body (11).

5. The ammonia corrosion testing apparatus according to claim 1, characterized in that, The lid (12) is sealed to the body (11) by the lid lifting rod (13) and the fixing bolt (14); and the test vessel (1) is provided with an air inlet (15) and an exhaust outlet (16).

6. The ammonia corrosion testing apparatus according to claim 1, characterized in that, The gas circulation pipeline includes a gas circulation coil (17) installed on the test vessel (1), and the gas circulation coil (17) is provided with multiple ventilation units (173).

7. The ammonia corrosion testing apparatus according to claim 6, characterized in that, The gas circulation coil (17) also includes an upper coil (171) and a lower coil (172) installed on the test vessel (1), and the upper coil (171) and the lower coil (172) are connected to the circulation pump (6) through a gas circulation coil connecting pipe (174).

8. The ammonia corrosion testing apparatus according to claim 6, characterized in that, The ventilation unit (173) is distributed circumferentially along the gas circulation coil (17) and is inclined relative to the gas circulation coil (17); the ventilation unit (173) is located in a one-to-one correspondence between the upper coil (171) and the lower coil (172).

9. The ammonia corrosion testing apparatus according to claim 8, characterized in that, Each of the ventilation units (173) includes at least one ventilation port (1731); and the angle between the central axis L1 and the central axis L2 of each ventilation port (1731) is α.

10. The ammonia corrosion testing apparatus according to claim 1, characterized in that, The test vessel (1) is provided with a sample holder (18), which includes a sample support rod (181) and a positioning pin (182); and the positioning pin (182) is evenly distributed along the sample support rod (181).

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