A liquid ammonia filling device and a liquid ammonia filling method for liquid ammonia corrosion experiments

Abstract

This invention provides a liquid ammonia filling device and method for liquid ammonia corrosion experiments. The device includes a liquid ammonia cylinder for filling a liquid ammonia test tank, and a circulating heat exchange pipe wound around the liquid ammonia cylinder. Both ends of the circulating heat exchange pipe are connected to a heating tank to form a closed loop for the flow of the heat exchange medium. A burner is installed below the heating tank to burn hydrogen produced by the ammonia decomposition device to heat the heat exchange medium flowing through the heating tank, thereby increasing the pressure of the liquid ammonia cylinder. This invention utilizes the high-temperature waste heat from the combustion of hydrogen during ammonia decomposition as a heat source, indirectly heating the liquid ammonia cylinder through the circulation of the heat exchange medium to create a pressure difference, achieving rapid liquid ammonia filling under conditions such as low temperatures in winter and insufficient cylinder capacity.

Description

Technical Field

[0001] This invention relates to the field of materials testing technology, and more specifically, to a liquid ammonia filling device and a liquid ammonia filling method for liquid ammonia corrosion experiments. Background Technology

[0002] Currently, liquid ammonia corrosion experiments commonly employ the gravimetric method for filling, relying on the pressure difference between the liquid ammonia cylinder and the test tank to transfer the liquid ammonia. Due to factors such as low outdoor temperatures in winter and heavy usage, the pressure in the liquid ammonia cylinder often drops below 0.4 MPa. Upon entering the test tank, the liquid ammonia rapidly vaporizes, and the system quickly reaches pressure equilibrium, leading to a significant reduction or even interruption in the filling rate. To improve filling efficiency, conventional methods require lowering the test tank temperature to increase the pressure difference. However, liquid ammonia corrosion experiments require the pre-addition of 0.1% water to simulate actual operating conditions. Temperatures below 0°C cause the water to freeze, damaging the medium's composition. Therefore, the initial temperature of the test tank must be controlled above 0°C, and cooling can only continue after the liquid ammonia and water have fully dissolved, resulting in an extremely long filling process and severely limiting experimental efficiency. Furthermore, liquid ammonia is a key experimental medium in ammonia energy research and materials testing, possessing characteristics of high toxicity, low temperature, and high volatility; direct discharge would cause severe environmental pollution. In laboratories, waste liquid ammonia is typically converted into nitrogen and hydrogen through an ammonia decomposition device before being ignited. The combustion product is water, which avoids pollution and prevents hydrogen accumulation and explosion, ensuring the safety of equipment and personnel. This combustion process is long-lasting and has a high calorific value, with flame temperatures reaching 1800~1900℃. However, this high-temperature waste heat is not recovered and utilized, resulting in significant energy waste.

[0003] Patent application CN201922392431.8 discloses a winter liquid ammonia storage tank pressurization device. It utilizes the residual heat of gaseous ammonia generated after liquid ammonia evaporation, heating the tank through an arc-shaped heat exchanger close to the outer wall to increase pressure. However, this solution uses unburned gaseous ammonia as a heat source, resulting in low temperature and limited heat exchange efficiency. Furthermore, it is only suitable for power plant denitrification systems to ensure continuous ammonia supply, and is not designed for the filling conditions required for liquid ammonia corrosion tests. Patent application 201220565880.3 discloses a 7N ultra-high purity liquid ammonia pump-free filling device. After the product tank is filled with liquid ammonia, the ammonia inlet valve of the vaporizer is opened, allowing some of the liquid ammonia to enter the vaporizer. The vaporizer heater heats the liquid ammonia, causing partial vaporization and increased pressure. The temperature and pressure of the vaporizer are controlled to ensure the liquid ammonia in the product tank reaches the filling pressure. This requires an external vaporizer for indirect pressurization and does not effectively utilize the hydrogen generated from laboratory ammonia decomposition.

[0004] Therefore, there is an urgent need for a device and method that can efficiently and safely pressurize liquid ammonia cylinders and rapidly add liquid ammonia, while also recovering and utilizing the waste heat from the combustion of hydrogen generated during laboratory ammonia decomposition. Summary of the Invention

[0005] In view of this, the present invention aims to propose a liquid ammonia filling device and a liquid ammonia filling method for liquid ammonia corrosion experiments, so as to solve the problems of low filling efficiency of liquid ammonia under working conditions such as low temperature in winter and insufficient cylinder capacity, the need for external equipment to indirectly increase pressure, and the inability to effectively utilize the waste heat of hydrogen combustion generated by ammonia decomposition in the prior art.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] This invention provides a liquid ammonia filling device for a liquid ammonia corrosion experiment, comprising a liquid ammonia cylinder for filling a liquid ammonia test tank, and a circulating heat exchange pipe wound around the liquid ammonia cylinder. Both ends of the circulating heat exchange pipe are connected to a heating tank to form a closed loop for the flow of the heat exchange medium. A burner is installed below the heating tank to burn hydrogen gas generated by an ammonia decomposition device to heat the heat exchange medium flowing through the heating tank, thereby increasing the pressure of the liquid ammonia cylinder.

[0008] This invention forms a closed loop with a circulating heat exchange pipe and a heating tank, directly using the waste heat from the combustion of hydrogen from ammonia decomposition to heat the liquid ammonia cylinder to increase the internal pressure. This eliminates the need for low-temperature pressure reduction during refueling, significantly improving the efficiency of liquid ammonia refueling in winter, while also achieving waste heat recovery and utilization, thus avoiding energy waste.

[0009] In this invention, the device is suitable for low-pressure conditions where the natural pressure inside the liquid ammonia cylinder is no higher than 0.4 MPa, including low-pressure scenarios caused by low temperature in winter or insufficient liquid ammonia in the cylinder. By using waste heat exchange to raise the temperature, the pressure of the liquid ammonia cylinder is stably regulated to within 1 MPa, thereby forming a stable pressure difference and realizing rapid and safe liquid ammonia filling.

[0010] Furthermore, it also includes a liquid storage tank located in the closed loop, the inlet and outlet of which are connected to the circulating heat exchange pipeline and the heating tank, respectively.

[0011] In this invention, the circulating heat exchange pipe is a flexible hose, which is spirally wound around the liquid ammonia cylinder with a winding spacing of ≤10cm, more preferably 1~5cm.

[0012] Furthermore, the heating tank includes an inner heating tank and an outer heating tank surrounding it; the upper part of the inner heating tank is provided with a first overflow port, and the outer heating tank is used to receive the heat exchange medium overflowing from the first overflow port.

[0013] In this invention, the heating tank adopts an inner and outer layer structure and is equipped with an overflow port, which can automatically adjust the liquid level and temperature of the inner layer, prevent the heat exchange medium from overheating and overflowing, and improve the system's operational safety and temperature control accuracy.

[0014] Furthermore, it also includes an overflow circuit disposed between the outer heating tank and the liquid storage tank.

[0015] This invention connects the outer heating tank to the liquid storage tank through an overflow loop, enabling full recycling of the heat exchange medium with no medium loss, thereby further improving the system's energy efficiency and operational continuity.

[0016] Furthermore, it also includes a lifting frame; the heating slot is installed on the lifting frame, and the lifting frame is used to adjust the distance between the heating slot and the burner to control the heating intensity.

[0017] This invention utilizes a lifting frame to adjust the distance between the heating tank and the burner, which allows for flexible control of the heating intensity and stable adjustment of the cylinder pressure, avoiding safety risks caused by sudden pressure increases.

[0018] Furthermore, the inlet and / or outlet of the circulating heat exchange pipeline are equipped with temperature sensors for real-time detection of the temperature of the heat exchange medium; the liquid ammonia cylinder is equipped with a pressure sensor for real-time monitoring of the internal pressure of the liquid ammonia cylinder.

[0019] This invention incorporates temperature and pressure sensors to monitor heat exchange temperature and cylinder pressure in real time, preventing cylinder explosions due to overheating and overpressure.

[0020] Furthermore, the outlet of the heating tank is equipped with a solenoid valve for adjusting the circulation flow rate.

[0021] This invention uses a solenoid valve to flexibly control the heat exchange and heating rate, thereby meeting the pressure requirements of different filling conditions.

[0022] Furthermore, it also includes a control system; the control system is electrically connected to the temperature sensor, pressure sensor and solenoid valve, and is used to receive feedback signals from the temperature sensor and pressure sensor in real time, and to adjust the flow rate of the solenoid valve.

[0023] This invention employs a control system to achieve signal feedback and automatic adjustment, forming a dual closed-loop intelligent control of temperature and pressure, further ensuring the safety of gas cylinders.

[0024] The present invention also provides a liquid ammonia injection method, which uses the apparatus described in the above technical solution and includes the following steps:

[0025] Step (1) Waste heat recovery

[0026] The waste heat from the combustion of hydrogen produced by ammonia decomposition is used to heat the heat exchange medium in the heating tank.

[0027] Step (2) Cyclic pressurization

[0028] The heated medium flows through a circulating heat exchange pipeline to heat and pressurize the liquid ammonia cylinder;

[0029] Step (3) Add liquid ammonia

[0030] The pressure difference between the pressurized liquid ammonia cylinder and the liquid ammonia test tank is used to achieve rapid liquid ammonia filling.

[0031] This method achieves liquid ammonia filling through hydrogen combustion waste heat recovery, circulating heat exchange pressurization, and differential pressure rapid filling. It eliminates the need to cool the test tank or use external electric heating equipment, fundamentally solving the problems of low cylinder pressure, slow filling, and easy freezing of the medium caused by low winter temperatures and insufficient liquid ammonia cylinder reserves. At the same time, it realizes the resource utilization of waste heat, significantly improving experimental efficiency and safety.

[0032] Furthermore, step (2) includes:

[0033] The temperature of the heat exchange medium at the outlet of the circulating heat exchange pipeline and / or the pressure inside the liquid ammonia cylinder are monitored in real time. When the monitored value reaches a preset proportional threshold, the distance between the heating tank and the burner is adjusted by the lifting frame, and / or the flow rate of the solenoid valve is adjusted to control the heating rate and circulation flow rate. When the monitored value reaches a preset target value, heating is stopped and the circulating heat exchange pipeline is dismantled for liquid ammonia injection.

[0034] This invention achieves stable and controllable pressure in liquid ammonia cylinders throughout the entire process by adjusting the heating distance and medium flow rate in stages of temperature and pressure, with no risk of overpressure. It is especially suitable for harsh working conditions such as low temperature and low liquid level, ensuring a stable and continuous filling process and greatly improving filling reliability and experimental data accuracy.

[0035] In this invention, the control system is configured as follows:

[0036] The system receives feedback signals from the temperature and pressure sensors in real time.

[0037] When the temperature or pressure reaches a preset percentage of a preset threshold, the drive motor is controlled to raise the heating tank to reduce heating, and / or the solenoid valve is controlled to reduce the circulation flow.

[0038] When the temperature or pressure reaches the preset target value, the drive motor is controlled to raise the heating tank and the solenoid valve is closed to end the heating cycle.

[0039] Compared with existing technologies, the liquid ammonia filling device and liquid ammonia filling method for liquid ammonia corrosion experiments described in this invention have the following advantages:

[0040] This invention utilizes the waste heat from the combustion of hydrogen produced by ammonia decomposition, employing an indirect heating method via water circulation. Using waste heat as a heat source eliminates the need for external energy consumption. Compared to conventional electric heating solutions such as resistance wires, this not only saves energy and reduces consumption but also avoids the safety hazards associated with electric heating, making it suitable for flammable and explosive experimental environments. Furthermore, this invention constructs a dual-layer feedback regulation mechanism for the heat exchange medium temperature and cylinder pressure. Combined with dual control methods—adjusting the heating distance with a lifting frame and regulating the medium flow with a solenoid valve—it achieves precise, closed-loop control of both heat exchange temperature and cylinder pressure. The unique structural design, combining inner and outer double-layer heating tanks with an overflow circuit, stabilizes the heat exchange medium level and circulation supply, effectively preventing leakage, buffering drastic temperature fluctuations, and ensuring continuous, stable, and safe operation of the entire system. Attached Figure Description

[0041] 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:

[0042] Figure 1 This is a schematic diagram of the structure of the device described in this invention;

[0043] Figure 2 This is a schematic diagram of the heating tank described in this invention.

[0044] Explanation of reference numerals in the attached figures:

[0045] 1. Storage tank cover; 2. Storage tank; 3. Circulation loop connector; 4. Overflow loop; 5. Heating tank inlet valve; 6. Heating tank inlet pipe; 7. Heating tank support plate; 8. Lifting frame; 9. Support column; 10. Heating tank; 11. Inner heating tank; 12. Outer heating tank; 13. Solenoid valve; 14. Heating tank outlet pipe connector; 15. Burner; 16. Support plate fixing clamp; 17. Platform fixing base plate; 18. Circulation heat exchange pipe; 19. Liquid ammonia cylinder; 20. Pressure gauge; 21. Liquid ammonia outlet pipe; 22. First overflow port; 23. Inner heating tank inlet; 24. Outer heating tank outlet; 25. Inner heating tank outlet. Detailed Implementation

[0046] The present invention will be further described below with reference to specific embodiments. First, it should be noted that the data in the following experimental examples were obtained by the inventors through numerous experiments. Due to space limitations, only a portion of these data is shown in the specification, and those skilled in the art can understand and implement the present invention based on this data. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various modifications or alterations to the invention, and these modifications or alterations also fall within the scope of protection of this application.

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0048] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0049] In liquid ammonia corrosion tests, liquid ammonia needs to be added to the test tank to create a corrosive environment. The transfer of liquid ammonia relies on the pressure difference between the liquid ammonia cylinder and the test tank. When a small amount of liquid ammonia enters the test tank, it rapidly vaporizes due to its low boiling point, causing the pressure to reach equilibrium with the cylinder. This significantly reduces the adding power, resulting in excessively long addition times. This not only prolongs the experimental cycle but may also lead to interruptions in the addition process, affecting the normal conduct of the experiment. Furthermore, the residual waste ammonia after the experiment needs to be treated harmlessly using an ammonia decomposition device. However, in the current treatment process, the hydrogen produced by ammonia decomposition burns into a high-temperature flame, and the large amount of heat energy contained within is not recovered and is directly lost, resulting in resource waste. In addition, the traditional method of adding liquid ammonia (cooling and depressurizing the test tank to increase the pressure difference) requires additional cooling of the liquid ammonia test tank during the addition process and is prone to problems such as water freezing and component deviation.

[0050] like Figure 1 As shown, this embodiment provides a liquid ammonia filling device for a liquid ammonia corrosion experiment, including a liquid ammonia cylinder 19 for filling liquid ammonia into a liquid ammonia test tank, and a circulating heat exchange pipe 18. The circulating heat exchange pipe 18 is wound around the liquid ammonia cylinder 19, and both ends of the circulating heat exchange pipe 18 are respectively connected to a heating tank 10 to form a closed loop for the flow of heat exchange medium. A burner 15 is provided below the heating tank 10 for burning hydrogen gas generated by the ammonia decomposition device to heat the heat exchange medium flowing through the heating tank 10, thereby increasing the pressure of the liquid ammonia cylinder 19.

[0051] It should be noted that the burner 15 is connected to the hydrogen outlet of the ammonia decomposition device, and uses the hydrogen generated by the ammonia decomposition device for combustion and heating; after the liquid ammonia corrosion test is completed, the outlet of the liquid ammonia test tank is connected to the inlet of the ammonia decomposition device, so as to pass the waste liquid ammonia after the experiment into the ammonia decomposition device for decomposition.

[0052] In this embodiment, a circulating heat exchange pipe 18 is wound around a liquid ammonia cylinder 19 for heating. This ensures uniform heating and stable temperature control, avoiding the problem of sudden pressure rise in the cylinder caused by localized high temperatures that are easily generated by resistance wire heating, thus ensuring cylinder safety. At the same time, after the liquid ammonia experiment, ammonia decomposition and hydrogen combustion will inevitably occur. This device can directly utilize the waste heat from the combustion and extract heat as needed, without the need for additional heating equipment.

[0053] In this embodiment, a liquid storage tank 2 located in the closed loop is also included. The inlet and outlet of the liquid storage tank 2 are respectively connected to the circulating heat exchange pipe 18 and the heating tank 10.

[0054] It should be noted that the heat exchange medium in the storage tank 2 first flows into the heating tank 10 for heating, then flows through the circulating heat exchange pipe 18 to heat the liquid ammonia cylinder 19, and finally flows back to the storage tank 2 to form a closed loop.

[0055] In a preferred embodiment, a circulation pump is also included. The circulation pump is located between the outlet of the liquid storage tank 2 and the inlet of the heating tank 10, and is used to pump the heat exchange medium in the liquid storage tank 2 into the heating tank 10 for heating.

[0056] It should be noted that a liquid storage tank cover 1 is detachably installed at the top opening of the liquid storage tank 2 for sealing the tank body and facilitating liquid replenishment; a circulation loop connector 3 and an interface connected to the overflow loop 4 are fixedly provided on the side wall of the liquid storage tank 2; the liquid storage tank 2 is connected to the outlet end of the circulating heat exchange pipe 18 through the circulation loop connector 3 to form an output channel for the heat exchange medium; the liquid storage tank 2 is connected to the outer heating tank 12 through the overflow loop 4 to return the overflowed heat exchange medium to the liquid storage tank 2.

[0057] In a preferred embodiment, the heat exchange medium is water, and the circulating heat exchange pipe 18 is tightly spirally wound around the liquid ammonia cylinder 19. Because the liquid ammonia cylinder 19 is relatively thick and the vaporization of liquid ammonia absorbs a large amount of heat, low heat exchange efficiency would significantly prolong the cylinder pressure increase time, failing to achieve the goal of reducing liquid ammonia refueling time. This can be addressed by increasing the heat exchange area or using a heat exchange medium with a high specific heat capacity to quickly increase the cylinder pressure and meet the requirements for rapid liquid ammonia refueling.

[0058] like Figure 2 As shown, in this embodiment, the heating tank 10 includes an inner heating tank 11 and an outer heating tank 12 sleeved around it; the upper part of the inner heating tank 11 is provided with a first overflow port 22, and the outer heating tank 12 is used to receive the heat exchange medium overflowing from the first overflow port 22.

[0059] In a preferred embodiment, the heating tank 10 has a double-layer nested structure, including an inner heating tank 11 and an outer heating tank 12 surrounding it. The inner heating tank 11 and the outer heating tank 12 are coaxially cylindrical. The inner heating tank 11 is used to contain the heat exchange medium and is directly heated by the burner 15, and the bottom height of the outer heating tank 12 is lower than the height of the first overflow port 22.

[0060] In this embodiment, the outer heating tank 12 and the inner heating tank 11 are provided with an outer heating tank cover plate and an inner heating tank cover plate, respectively. The inner heating tank cover plate has a circular cross-section along its axial direction, and the outer heating tank cover plate has an annular cross-section along its axial direction. In the axial direction, there is a gap between the outer heating tank cover plate and the outer wall of the inner heating tank 11. The heat exchange medium flows into the outer heating tank 12 from the first overflow port 22 through the gap. The outer heating tank cover plate and the inner heating tank cover plate are provided with handles to facilitate lifting the cover plate.

[0061] It should be noted that when the liquid level in the inner heating tank 11 rises to the overflow port position due to thermal expansion or excessive filling, the excess heat exchange medium can automatically overflow and fall into the outer heating tank 12 below, thereby achieving automatic liquid level balance and overflow collection.

[0062] In a preferred embodiment, the system further includes a heating tank inlet pipe 6 connected to the lower side wall of the inner heating tank 11, and a heating tank inlet valve 5. It also includes an inner heating tank inlet 23 and an inner heating tank outlet 25. The inner heating tank inlet 23 is located at the end of the heating tank inlet pipe 6 and is located at the bottom of the inner heating tank 11. The inner heating tank outlet 25 is located on the side wall of the inner heating tank 11 and communicates with a heating tank outlet pipe connector 14. The other end of the heating tank outlet pipe connector 14 is connected to the circulating heat exchange pipe 18, thereby forming a bottom-in, top-out circulating flow channel for the heat exchange medium within the inner heating tank 11. The inlet end of the circulating pump is connected to the outlet of the storage tank 2, and the outlet end of the circulating pump is connected to the heating tank inlet pipe 6. The heating tank inlet valve 5 is located on the pipe between the outlet end of the circulating pump and the inner heating tank inlet 23.

[0063] It should be noted that the first overflow port 22 is located on the upper side wall of the inner heating tank 11, and its axial height is higher than the position of the inner heating tank outlet 25; the outer heating tank outlet 24 is located at the bottom of the outer heating tank 12 and is used to discharge the overflow medium.

[0064] In this embodiment, an overflow circuit 4 is also included, and the outer heating tank 12 is connected to the liquid storage tank 2 through the overflow circuit 4.

[0065] In this embodiment, a lifting frame 8 is also included; the heating groove 10 is installed on the lifting frame 8, and the lifting frame 8 is used to adjust the distance between the heating groove 10 and the burner 15 to control the heating intensity.

[0066] In a preferred embodiment, a frame fixing base plate 17 is fixedly installed at the bottom of the lifting frame 8, the burner 15 is located on the frame fixing base plate 17, and the support column 9 is vertically arranged on the frame fixing base plate 17 and located on both sides of the lifting frame 8; a heating groove support plate 7 is installed at the upper end of the support column 9 to support the heating groove 10, and the heating groove support plate 7 is slidably connected to the lifting frame 8, so that the lifting frame 8 can drive the heating groove support plate 7 to move up and down along the support column 9; a support plate fixing clamp 16 is provided at the connection between the heating groove support plate 7 and the support column 9, which is used to lock the heating groove support plate 7 to the support column 9 after adjusting the height to prevent it from shifting during operation.

[0067] In this embodiment, the inlet and / or outlet of the circulating heat exchange pipeline 18 are equipped with temperature sensors to detect the temperature of the heat exchange medium in real time; the liquid ammonia cylinder 19 is equipped with a pressure sensor to monitor the internal pressure of the liquid ammonia cylinder 19 in real time.

[0068] Specifically, a platinum resistance thermometer is installed in the inner heating tank 11 to monitor the inlet water temperature in real time, and a thermocouple is installed at the circulation loop connector 3 to monitor the return water temperature in real time. The temperature signal is transmitted to the control system as a feedback signal for the system to control the temperature of the heat exchange medium. A pressure gauge 20 is connected to the liquid ammonia cylinder 19, and the pressure signal is transmitted to the control system as a feedback signal for the system to control the temperature of the circulating medium, ensuring that the internal pressure of the cylinder is within a preset safe and efficient range during the filling process.

[0069] It should be noted that the industrial liquid ammonia cylinder is designed to withstand a pressure of 2.16 MPa. Excessive heat absorption can cause the internal pressure to rise sharply, posing a risk of explosion. Therefore, pressure and temperature sensors are installed to monitor and provide feedback on the cylinder pressure and heat exchange medium temperature in real time. By adjusting the medium flow rate and controlling the heat exchange temperature, the cylinder pressure is stabilized below 1 MPa to ensure system safety.

[0070] Specifically, at the start of heating, both the circulating pump and solenoid valve 13 remain in the active state. The heat exchange medium flows from the storage tank 2 into the inner heating tank 11 for heating. At this time, the liquid level in the inner heating tank 11 is lower than the first overflow port 22. All the heated heat exchange medium flows into the circulating heat exchange pipe 18, and the liquid ammonia cylinder 19 heats up at a high rate. When the pressure gauge 20 approaches the preset value, the solenoid valve 13 is appropriately closed to reduce the flow rate of the heat exchange medium. At this time, the liquid level in the inner heating tank 11 rises to the level of the first overflow port 22. At a certain height, some of the heat exchange medium flows back to the storage tank 2 through the overflow circuit 4. In actual operation, the lifting frame 8 will also be raised to increase the distance between the heating tank 10 and the burner 15, thereby reducing the temperature and flow rate of the water in the tank and decreasing the heating rate of the liquid ammonia cylinder 19. This graded and fine adjustment method can accurately control the pressure inside the liquid ammonia cylinder 19 within the target value ±0.05MPa, which can not only ensure the heating efficiency in the early stage, but also prevent the pressure inside the cylinder from rising suddenly when the pressure is close to the safety limit, effectively eliminating the risk of explosion.

[0071] In this embodiment, the outlet of the heating tank 10 is equipped with a solenoid valve 13 for adjusting the circulation flow rate.

[0072] In a preferred embodiment, the maximum flow rate of the solenoid valve 13 is consistent with the flow rate of the circulating pump to avoid overpressure and ensure stable and safe operation of the heat exchange circuit.

[0073] It should be noted that, since the inner heating tank 11 is provided with a first overflow port 22, when the temperature needs to be adjusted, the opening angle of the solenoid valve 13 can be controlled by the control system. When the flow rate of the solenoid valve 13 is small (i.e., the water output is slow), the inner liquid level will continue to rise, and hot water will enter the outer heating tank 12 from the first overflow port 22 and enter the storage tank 2 through the outer heating tank outlet 24, so as to realize the recycling of the heat exchange medium.

[0074] In this embodiment, the liquid ammonia cylinder 19 is provided with a liquid ammonia outlet pipe 21 for adding liquid ammonia to the liquid ammonia test tank.

[0075] In this embodiment, a control system is also included; the control system is electrically connected to the temperature sensor, pressure sensor and solenoid valve 13, and is used to receive feedback signals from the temperature sensor and pressure sensor in real time, and to adjust the flow rate of the solenoid valve 13.

[0076] In a preferred embodiment, the lifting frame 8 is equipped with a drive motor, which is electrically connected to the control system. The control system adjusts the circulation flow by controlling the solenoid valve 13 and adjusts the distance between the heating tank 10 and the burner 15 by controlling the drive motor.

[0077] This embodiment also provides a liquid ammonia injection method, using the apparatus described in the above technical solution, including the following steps:

[0078] Step (1) Waste heat recovery

[0079] The heat exchange medium in heating tank 10 is heated by the waste heat from the combustion of hydrogen produced by ammonia decomposition.

[0080] Step (2) Cyclic pressurization

[0081] The temperature of the heat exchange medium at the outlet of the circulating heat exchange pipe 18 and / or the pressure inside the liquid ammonia cylinder 19 are monitored in real time. When the monitored value reaches a preset proportional threshold, the distance between the heating tank 10 and the burner 15 is adjusted by the lifting frame 8, and / or the flow rate of the solenoid valve 13 is adjusted to control the heating rate and circulation flow rate. When the monitored value reaches a preset target value, heating is stopped and the circulating heat exchange pipe 18 is removed for liquid ammonia injection.

[0082] Step (3) Add liquid ammonia

[0083] The pressure difference between the pressurized liquid ammonia cylinder 19 and the liquid ammonia test tank is used to achieve rapid liquid ammonia filling.

[0084] It should be noted that in this embodiment, ammonia decomposes to produce hydrogen gas. Directly extinguishing the flame will cause hydrogen gas to accumulate, which poses an explosion risk.

[0085] In this embodiment, the following steps are also included:

[0086] (1) The circulating heat exchange pipe 18 is spirally wound around the liquid ammonia cylinder 19. The two ends of the circulating heat exchange pipe 18 are respectively connected to the heating tank 10 and the liquid storage tank 2. The heating tank 10 and the liquid storage tank 2 are connected by a pipe to form a closed-loop heat exchange circuit. Adjust the lifting frame 8 so that the heating tank 10 is placed 3~7cm above the burner 15 to retain oxygen entering the space.

[0087] (2) Turn on the control system and set the temperature of the heat exchange medium and the pressure of the liquid ammonia cylinder 19;

[0088] (3) Inject heat exchange medium into the inner heating tank 11 until the scale reaches the first overflow port 22 and then close it to make the inner heating tank 11 full of liquid and ignite the ammonia decomposition mixture; when the temperature of the heat exchange medium in the heating tank 10 reaches the set value, open the water inlet and outlet of the heating tank 10 and the water inlet and outlet of the storage tank 2, and the device enters the automatic operation state.

[0089] (4) When the temperature of the heat exchange medium or the pressure of the liquid ammonia cylinder 19 reaches the preset ratio of the set value, adjust the distance between the heating tank 10 and the burner 15 and the flow rate of the water outlet of the heating tank 10, and repeat the above adjustment process; when the temperature of the heat exchange medium or the pressure inside the liquid ammonia cylinder 19 reaches the predetermined value, remove the circulating heat exchange pipe 18 and add liquid ammonia.

[0090] Example 1

[0091] Liquid ammonia corrosion test conditions: 12.00 kg liquid ammonia + 30.0 mg oxygen + 0.1% wt water, test temperature (25±1)℃, outdoor ambient temperature 7℃, liquid ammonia temperature inside liquid ammonia cylinder 19 is 7℃.

[0092] The steps for adding fuel using the device described in this invention are as follows:

[0093] The circulating heat exchange pipe 18 is tightly wrapped around the outer wall of the liquid ammonia cylinder 19, and the two ends of the hose are connected to the heating tank 10 and the liquid storage tank 2 respectively through the circulating loop connector 3 to form a closed heat exchange loop.

[0094] Turn on the control system and set the upper limit of the heat exchange medium temperature to 40℃ and the upper limit of the liquid ammonia cylinder pressure to 1MPa.

[0095] Adjust the lifting frame 8 to place the heating slot 10 5cm above the burner 15 to ensure the best heating position and air intake space;

[0096] Open the circulation pump and the inlet valve 5 of the heating tank. The heat exchange medium in the storage tank 2 enters the inner heating tank 11 through the inlet pipe 6 of the heating tank. When the water level reaches the first overflow port 22, close the circulation pump and the inlet valve 5 of the heating tank to keep the inner heating tank 11 full. At the same time, ignite the hydrogen-nitrogen mixture produced by ammonia decomposition.

[0097] The system monitors the temperature of the heat exchange medium in the heating tank 10 in real time. When the temperature reaches 40℃, the heating tank outlet solenoid valve 13, the circulation pump and the heating tank inlet valve 5 are opened, and the system enters the automatic circulation working state. The control system continuously monitors the temperature of the heat exchange medium and the pressure of the liquid ammonia cylinder 19.

[0098] The control system performs hierarchical adjustments according to preset logic:

[0099] When the temperature of the heat exchange medium flowing out of the circulating heat exchange pipe 18 reaches 32℃ or the pressure of the liquid ammonia cylinder 19 reaches 0.8MPa, the lifting frame 8 drives the heating tank 10 to rise by 5cm, and the heating tank outlet solenoid valve 13 is adjusted to 50% flow.

[0100] When the temperature of the heat exchange medium reaches 36℃ or the pressure of the liquid ammonia cylinder 19 reaches 0.9MPa, the lifting frame 8 drives the heating tank 10 to rise by 10cm, and the solenoid valve 13 at the outlet of the heating tank is adjusted to 25% flow rate.

[0101] When the temperature of the heat exchange medium reaches 40℃ or the pressure of the liquid ammonia cylinder 19 reaches 1MPa, the lifting frame 8 raises the heating tank 10 by 15cm, and the solenoid valve 13 at the outlet of the heating tank closes. In actual operation, the pressure of the liquid ammonia cylinder 19 reaches 1MPa first, and the solenoid valve 13 automatically closes.

[0102] After shutting down, remove the circulating heat exchange pipe 18 and weigh the liquid ammonia cylinder 19.

[0103] The temperature of the liquid ammonia test tank was preset to 2℃ to prevent water from freezing. After evacuating the liquid ammonia test tank, 30mg of oxygen and 12.00g of water were added sequentially. The outlet valve 19 of the liquid ammonia cylinder was opened, and liquid ammonia was added using the pressure difference between the cylinder and the liquid ammonia test tank until all 12.00kg of liquid ammonia had been added. During the addition process, the pressure in the liquid ammonia test tank rose slowly, reaching a maximum of 0.7MPa, maintaining an effective pressure difference throughout, and the addition was completed in 20 minutes.

[0104] Comparative Example 1

[0105] Same test conditions: 12.00kg liquid ammonia + 30.0mg oxygen + 0.1%wt water, test temperature (25±1)℃, outdoor temperature 7℃, liquid ammonia cylinder 19 pressure approximately 0.4MPa, no auxiliary heating device used, pressure difference is formed by lowering the temperature of the liquid ammonia test tank.

[0106] The liquid ammonia test tank was set to 2℃. After evacuation, oxygen and water were added, and the cylinder valve was opened for direct filling. As liquid ammonia entered, the pressure in the test tank rose rapidly, the pressure difference with the cylinder decreased quickly, and the liquid ammonia inflow rate gradually dropped to 0. The highest pressure reached 0.4MPa. In order to ensure that the added trace amount of water and liquid ammonia were fully miscible, the test tank needed to be kept at above 0℃ for more than 60 minutes for mixing. Then, the test tank was cooled to -30℃ to reduce the pressure in the test tank. Finally, the filling was completed after 156 minutes.

[0107] Under the same outdoor temperature and filling volume conditions, the traditional filling method takes up to 156 minutes. During the filling process, additional cooling of the liquid ammonia test tank is required, which consumes a lot of electrical energy and may cause problems such as water freezing and component deviation. However, by using the device described in this invention to assist filling, the liquid ammonia cylinder 19 can be stably pressurized, maintaining a continuous pressure difference between the cylinder and the liquid ammonia test tank. There is no need to cool the liquid ammonia test tank, the medium is mixed more evenly, and the filling time is only 20 minutes, which greatly improves the test efficiency.

[0108] 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 liquid ammonia filling device for a liquid ammonia corrosion experiment, comprising a liquid ammonia cylinder (19) for filling liquid ammonia into a liquid ammonia test tank, characterized in that, It also includes a circulating heat exchange pipe (18), which is wound around the liquid ammonia cylinder (19). The two ends of the circulating heat exchange pipe (18) are respectively connected to the heating tank (10) to form a closed loop for the flow of heat exchange medium. A burner (15) is provided below the heating tank (10) to burn the hydrogen produced by the ammonia decomposition device to heat the heat exchange medium flowing through the heating tank (10) and increase the pressure of the liquid ammonia cylinder (19).

2. The apparatus according to claim 1, characterized in that, It also includes a liquid storage tank (2) located in the closed loop, the inlet and outlet of which are connected to the circulating heat exchange pipe (18) and the heating tank (10), respectively.

3. The apparatus according to claim 2, characterized in that, The heating tank (10) includes an inner heating tank (11) and an outer heating tank (12) surrounding it; the inner heating tank (11) is provided with a first overflow port (22) at its upper part, and the outer heating tank (12) is used to receive the heat exchange medium overflowing from the first overflow port (22).

4. The apparatus according to claim 3, characterized in that, It also includes an overflow circuit (4) disposed between the outer heating tank (12) and the liquid storage tank (2).

5. The apparatus according to claim 1, characterized in that, It also includes a lifting frame (8); the heating tank (10) is installed on the lifting frame (8), and the lifting frame (8) is used to adjust the distance between the heating tank (10) and the burner (15) to control the heating intensity.

6. The apparatus according to claim 1, characterized in that, Temperature sensors are provided at the inlet and / or outlet of the circulating heat exchange pipeline (18) to detect the temperature of the heat exchange medium in real time; a pressure sensor is provided on the liquid ammonia cylinder (19) to monitor the internal pressure of the liquid ammonia cylinder (19) in real time.

7. The apparatus according to claim 6, characterized in that, The outlet of the heating tank (10) is equipped with a solenoid valve (13) for adjusting the circulation flow rate.

8. The apparatus according to claim 7, characterized in that, It also includes a control system; the control system is electrically connected to the temperature sensor, pressure sensor and solenoid valve (13), and is used to receive feedback signals from the temperature sensor and pressure sensor in real time and adjust the flow rate of the solenoid valve (13).

9. A method for adding liquid ammonia, using the apparatus described in any one of claims 1 to 8, characterized in that, Includes the following steps: Step (1) Waste heat recovery The heat exchange medium in the heating tank (10) is heated by the waste heat from the combustion of hydrogen produced by ammonia decomposition. Step (2) Cyclic pressurization The heated medium flows through the circulating heat exchange pipe (18) to heat and pressurize the liquid ammonia cylinder (19); Step (3) Add liquid ammonia The pressure difference between the pressurized liquid ammonia cylinder (19) and the liquid ammonia test tank is used to achieve rapid liquid ammonia filling.

10. The method for rapid liquid ammonia injection according to claim 9, characterized in that, Step (2) includes: Real-time monitoring of the temperature of the heat exchange medium at the outlet end of the circulating heat exchange pipeline (18) and / or the pressure inside the liquid ammonia cylinder (19); When the monitored value reaches the preset proportional threshold, the distance between the heating tank (10) and the burner (15) is adjusted by the lifting frame (8), and / or the flow rate of the solenoid valve (13) is adjusted to control the heating rate and circulation flow rate; When the monitored value reaches the preset target value, heating is stopped and the circulating heat exchange pipeline (18) is removed, and liquid ammonia is injected.

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