Ammonia gas leakage prevention protective shed for ammonia dual-fuel host detection and control method

Abstract

The invention discloses an ammonia gas leakage prevention protective shed for ammonia dual-fuel host detection and a control method, and belongs to the technical field of ammonia dual-fuel host production detection. The protective shed comprises a protective shed body, a transparent protective door system, an exhaust filtering system, a spraying system and an ammonia gas detection system, the protective shed body is composed of metal supports, metal transverse rods, a top plate and wallboards. The transparent protective door system is quickly closed through a worm and gear transmission mechanism; the exhaust filtering system purifies ammonia gas by adopting a four-stage filtering combination; the spraying system forms a water mist curtain through a square pipe and a nozzle; the controller carries out three-level threshold judgment according to signals of the ammonia gas detector, and multi-level linkage protection of detection, closing, exhausting, filtering and spraying is achieved. According to the invention, the problems of rapid sealing, efficient purification and accurate control of ammonia gas leakage during detection of the ammonia dual-fuel host are solved, and the safety and continuity of detection operation are improved.

Description

Technical Field

[0001] This invention relates to the field of ammonia dual-fuel main engine production and testing technology, and in particular to a protective shed and control method for preventing ammonia leakage during ammonia dual-fuel main engine testing. Background Technology

[0002] With the International Maritime Organization (IMO) imposing increasingly stringent carbon emission requirements on ships, the application of ammonia fuel as a zero-carbon energy source in marine propulsion has received widespread attention. As a core power unit for ships, ammonia dual-fuel main engines require numerous performance tests during manufacturing, including fuel injection system testing, combustion performance testing, and sealing testing. These tests pose a risk of ammonia leakage, which could threaten the health of personnel and the surrounding environment.

[0003] In existing technologies, ammonia leaks are typically handled by enhanced ventilation or open-air water curtain dilution. For example, roof ventilators and sprinkler systems are installed in ammonia fuel engine assembly plants to reduce ammonia concentration through large-space ventilation and physical absorption. However, this open-air approach presents the following technical problems:

[0004] First, open ventilation cannot effectively limit the diffusion of ammonia when the leakage is large, and ammonia may still escape into the surrounding area, causing environmental pollution and personal injury.

[0005] Second, open-type water curtain dilution requires a large amount of water resources, and the absorption efficiency is greatly affected by the ambient temperature and humidity, resulting in unstable purification effects.

[0006] Third, the existing treatment system lacks a rapid containment mechanism, which makes it impossible to isolate the leak source in time in the early stages of the leak, resulting in a continuous leakage of ammonia.

[0007] Fourth, the existing system has a single response strategy, which usually adopts the mode of detection as the maximum response, which can easily lead to over-protection and affect the continuity and efficiency of detection operations.

[0008] Therefore, how to provide a protective device that can quickly seal the leak space, efficiently purify ammonia gas, and achieve precise graded response during the detection of ammonia dual-fuel main engine has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] The purpose of this invention is to provide a protective enclosure and control method for preventing ammonia leakage in a dual-fuel ammonia main engine, thereby solving the aforementioned problems existing in the prior art.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A protective canopy for preventing ammonia leakage during testing of a dual-fuel ammonia main engine includes a canopy body, a transparent protective door system, an exhaust filtration system, a spray system, and an ammonia detection system.

[0012] The protective canopy consists of a metal frame, metal crossbars, a top plate, and wall panels. The metal crossbars are fixedly installed on the top of the metal frame, the top plate is located on the top of the metal crossbars, and the wall panels are fixedly installed on both sides of the metal frame. The front of the metal frame is open.

[0013] The transparent protective door system includes a winding box, a winding rod, a transmission mechanism, a transparent protective door, and a motor. The winding box is fixedly installed on the front of the metal bracket, the winding rod is movably installed inside the winding box, the transmission mechanism is located inside the winding box and is connected to the winding rod for transmission, the motor is connected to the transmission mechanism and fixedly installed on the surface of the inner wall of the winding box, and the transparent protective door is movably connected to the surface of the winding rod and can be raised and lowered along the opening direction of the winding box to close or open the opening on the front of the metal bracket.

[0014] The exhaust filtration system includes an exhaust fan, an inlet, an exhaust hood, a filter box, and a blower. The exhaust fan is fixedly installed on the top of the roof panel, the inlet is opened on the roof panel, the exhaust hood is fixedly installed on the top of the inlet and connected to the exhaust fan, one end of the filter box is connected to the exhaust hood, and the blower is connected to the other end of the filter box. The exhaust filtration system is used to exhaust and filter ammonia gas inside the protective shed.

[0015] The sprinkler system includes a square tube, nozzles, and an inlet pipe. The square tube is fixedly installed at the bottom of a metal crossbar, multiple nozzles are connected to the bottom of the square tube, and the inlet pipe is connected to the surface of the square tube and connected to a water source.

[0016] The ammonia detection system includes an ammonia detector and an air inlet. The ammonia detector is fixedly installed on the inside of a metal bracket, and the air inlet is located on the wall behind the metal bracket.

[0017] The controller controls the motor to drive the transparent protective door to descend and close based on the detection signal from the ammonia detector, controls the exhaust fan and blower to start exhausting, and controls the water inlet pipe to spray water, forming a multi-level linkage protection system of detection-closure-exhaust-filtration-spraying.

[0018] In some specific embodiments, the transmission mechanism includes a worm gear and a worm. The worm gear is fixedly mounted on the surface of the winding rod, and the worm meshes with the surface of the worm gear. The output shaft of the motor is fixedly connected to the bottom of the worm, and the top of the worm is movably connected to the surface of the inner wall of the winding box through a bearing seat. When the ammonia detector detects that the ammonia concentration exceeds the standard, the controller starts the motor to drive the worm to rotate, which in turn drives the worm gear and the winding rod to rotate, causing the transparent protective door to descend and close the protective canopy.

[0019] In some specific embodiments, a plastic plate is movably connected to the surface of the inner wall of the opening via a pivot pin, and a baffle is fixedly installed on the top of the plastic plate, with the baffle located on the side of the plastic plate away from the pivot pin connection end; the plastic plate remains horizontally closed to the opening under the action of gravity, and flips upward to open under the action of the exhaust fan's airflow.

[0020] In some specific embodiments, the interior of the filter box is arranged sequentially from the input end to the output end with a polyester fiber mesh, granular activated carbon, a type 4A molecular sieve, and a high-efficiency meltblown cloth. The top of the filter box is movably connected to a sealing plate by a shaft pin. The polyester fiber mesh is used to filter large particulate impurities, the granular activated carbon is used to adsorb ammonia molecules, the type 4A molecular sieve is used to selectively adsorb small molecule gases, and the high-efficiency meltblown cloth is used to finely filter residual particles.

[0021] In some specific embodiments, multiple metal crossbars are fixedly installed in parallel between the tops of two metal brackets, a top plate is laid on top of the multiple metal crossbars, wall panels are fixedly installed on both sides and the back of the metal brackets, and an air inlet is located at the lower part of the back wall panel. The air inlet and the exhaust fan form an airflow channel from bottom to top, forming a cross flow field with the spray direction of the spray system.

[0022] In some specific embodiments, multiple square tubes are fixedly installed in parallel at the bottom of a metal crossbar. Each square tube has multiple nozzles connected to its bottom. A solenoid valve is installed on the water inlet pipe. The controller controls the solenoid valve to open according to the detection signal of the ammonia detector, so that water passes through the square tubes and nozzles to form a water mist curtain. The spraying system is linked with the exhaust filtration system. After the water mist absorbs ammonia, it is discharged through the exhaust filtration system.

[0023] In some specific embodiments, the ammonia detector is located in the middle of the inner side of the metal support to monitor the ammonia concentration inside the protective shed in real time; when the ammonia concentration exceeds the first preset threshold, the controller starts the transparent protective door to descend and the exhaust filtration system to work; when the ammonia concentration exceeds the second preset threshold, the controller starts the spray system; when the ammonia concentration exceeds the third preset threshold, the controller starts the audible and visual alarm device; the first preset threshold is less than the second preset threshold, and the second preset threshold is less than the third preset threshold.

[0024] In some specific embodiments, a communication device is also included;

[0025] When the ammonia detector stops emitting alarm signals, the controller records the location, time, peak concentration, and handling measures of the current leak event, and generates a maintenance report which is sent to the monitoring center via a communication device.

[0026] In another embodiment, a control method for a protective shed for preventing ammonia leakage during the detection of a dual-fuel ammonia main engine, applied to the aforementioned protective shed, includes:

[0027] The signal from the ammonia detector is collected in real time to monitor the ammonia concentration inside the protective shed;

[0028] If the ammonia detector detects that the ammonia concentration exceeds the first preset threshold, the motor will be started to drive the transparent protective door to descend and close the protective shed, and the exhaust fan and blower will be started at the same time to filter the exhaust.

[0029] If the ammonia concentration exceeds the second preset threshold, the solenoid valve of the water inlet pipe will be opened for spraying.

[0030] If the ammonia concentration drops to a safe range after a preset time, the spraying and venting will stop, and the transparent protective door will be raised.

[0031] If the ammonia concentration continues to exceed the third preset threshold within a preset time, an audible and visual alarm will be activated and the exhaust filtration will continue until manual intervention is required.

[0032] In another embodiment, an ammonia dual-fuel main engine detection system includes the aforementioned protective canopy for preventing ammonia leakage during ammonia dual-fuel main engine detection.

[0033] The beneficial effects of this invention are:

[0034] The protective canopy and control method for preventing ammonia leakage in dual-fuel main engine detection provided by this invention have the following advantages compared with the prior art:

[0035] First, the present invention uses a metal bracket, wall panels, and top panel to form the protective shed body, and with the help of a transparent protective door system, it can form a closed space during the inspection operation, effectively limiting the diffusion range of ammonia gas, and solving the technical problem that open treatment cannot be effectively sealed.

[0036] Secondly, the present invention uses a worm gear transmission mechanism to drive the transparent protective door. By utilizing the self-locking characteristics of the worm gear, the protective door is ensured to remain stable in the closed state, while achieving rapid response, thus resolving the technical contradiction between closing and rapid opening and closing.

[0037] Third, the present invention has an opening in the top plate and forms a gravity self-sealing structure through a plastic plate and baffles. The opening is automatically closed when the exhaust fan is not working and automatically opened when exhausting, without the need for additional power and control, thus simplifying the system structure.

[0038] Fourth, the present invention employs a four-stage filtration combination, which sets up polyester fiber mesh, granular activated carbon, molecular sieve and high-efficiency meltblown cloth in a specific order to form a gradient filtration, thereby improving the ammonia purification efficiency and reducing water consumption.

[0039] Fifth, the present invention adopts a three-level threshold control strategy, which responds in stages according to the ammonia concentration, avoiding over-response or under-response caused by a single threshold, and improving the continuity of detection operations while ensuring safety.

[0040] Sixth, this invention achieves multi-level linkage of detection, sealing, exhaust, filtration, and spraying to form a complete protection system. The coordinated operation of each system improves the overall protection effect.

[0041] Seventh, the present invention places the spraying system at the bottom of the metal crossbar, forming a cross flow field with the exhaust system, which enhances the contact between ammonia gas and sprayed water mist and improves absorption efficiency.

[0042] Eighth, the present invention is equipped with a communication device that can automatically record leakage events and generate maintenance reports, thereby realizing intelligent management and traceability. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the metal support structure in this invention;

[0044] Figure 2 This is a schematic diagram of the wall panel structure in this invention;

[0045] Figure 3 This is a schematic diagram of the top plate structure in this invention;

[0046] Figure 4 This is a schematic diagram of the exhaust hood structure in this invention;

[0047] Figure 5 In this invention Figure 4 Enlarged structural diagram at point A in the middle;

[0048] Figure 6 This is a schematic diagram of the square tube structure of the present invention;

[0049] Figure 7 This is a schematic diagram of the filter box structure in this invention;

[0050] Figure 8 This is a schematic diagram of the worm gear structure in this invention;

[0051] Figure 9 This is a flowchart of the control method of the present invention.

[0052] In the attached diagram: 1. Metal bracket; 2. Metal crossbar; 3. Top plate; 4. Wall panel; 5. Winding box; 6. Winding rod; 7. Worm gear; 8. Worm; 9. Motor; 10. Transparent protective door; 11. Exhaust fan; 12. Opening; 13. Plastic sheet; 14. Baffle; 15. Exhaust hood; 16. Filter box; 17. Fan; 18. Polyester fiber mesh; 19. Granular activated carbon; 20. Type 4A molecular sieve; 21. High-efficiency meltblown fabric; 22. Sealing plate; 23. Square tube; 24. Nozzle; 25. Water inlet pipe; 26. Ammonia detector. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0054] Reference Figures 1 to 8 The protective canopy for preventing ammonia leakage during testing of a dual-fuel ammonia main unit, shown in the figure, includes a protective canopy body, a transparent protective door system, an exhaust filtration system, a spray system, and an ammonia detection system;

[0055] The protective canopy body includes a metal frame 1, a metal crossbar 2, a top plate 3, and wall panels 4. The metal crossbar 2 is fixedly installed on the top of the metal frame 1, the top plate 3 is set on the top of the metal crossbar 2, and the wall panels 4 are fixedly installed on both sides of the metal frame 1. The front of the metal frame 1 is open.

[0056] The transparent protective door system includes a winding box 5, a winding rod 6, a transmission mechanism, a transparent protective door 10, and a motor 9. The winding box 5 is fixedly installed on the front of the metal bracket 1. The winding rod 6 is movably installed inside the winding box 5. The transmission mechanism is located inside the winding box 5 and is connected to the winding rod 6. The motor 9 is connected to the transmission mechanism and is fixedly installed on the surface of the inner wall of the winding box 5. The transparent protective door 10 is movably connected to the surface of the winding rod 6 and can be raised and lowered along the opening direction of the winding box 5 to close or open the opening on the front of the metal bracket 1.

[0057] The exhaust filtration system includes an exhaust fan 11, a port 12, an exhaust hood 15, a filter box 16, and a fan 17. The exhaust fan 11 is fixedly installed on the top of the top plate 3. The port 12 is opened on the top plate 3. The exhaust hood 15 is fixedly installed on the top of the port 12 and is connected to the exhaust fan 11. One end of the filter box 16 is connected to the exhaust hood 15, and the fan 17 is connected to the other end of the filter box 16. The exhaust filtration system is used to discharge and filter ammonia gas inside the protective shed.

[0058] The sprinkler system includes a square tube 23, a nozzle 24, and a water inlet pipe 25. The square tube 23 is fixedly installed at the bottom of the metal crossbar 2. Multiple nozzles 24 are connected to the bottom of the square tube 23. The water inlet pipe 25 is connected to the surface of the square tube 23 and is connected to a water source.

[0059] The ammonia detection system includes an ammonia detector 26 and an air inlet. The ammonia detector 26 is fixedly installed on the inside of the metal bracket 1, and the air inlet is located on the wall behind the metal bracket 1.

[0060] The controller controls the motor 9 to drive the transparent protective door 10 to descend and close based on the detection signal of the ammonia detector 26, controls the exhaust fan 11 and the blower 17 to start exhausting, and controls the water inlet pipe 25 to spray water, forming a multi-level linkage protection of detection-closure-exhaust-filtration-spraying.

[0061] In this embodiment, the protective canopy body includes two metal supports 1, multiple metal crossbars 2, a top plate 3, and wall panels 4. Figure 1 and Figure 2 As shown, the metal bracket 1 is a vertically installed support structure made of metal profiles. Adjustable feet or casters can be installed at the bottom for easy adjustment of level and movement. Multiple metal crossbars 2 are fixedly installed parallel to each other between the tops of two metal brackets 1, forming a horizontal support frame. A top plate 3 is laid above the multiple metal crossbars 2, forming a closed top. Wall panels 4 are fixedly installed on the sides and back of the metal bracket 1, forming closed sides and back. The front of the metal bracket 1 is open, allowing the ammonia dual-fuel main unit to enter and exit the protective shed for inspection operations.

[0062] The transparent safety door system includes a winding box 5, a winding rod 6, a transmission mechanism, a transparent safety door 10, and a motor 9. For example... Figure 1 , Figure 4 and Figure 8 As shown, the winding box 5 is fixedly installed on the top front of the metal bracket 1 and has a long, rectangular box structure. The winding rod 6 is movably installed inside the winding box 5 and can rotate around its own axis. The transmission mechanism is located inside the winding box 5 and is connected to the winding rod 6 for transmission. The motor 9 is connected to the transmission mechanism and fixedly installed on the surface of the inner wall of the winding box 5. The transparent protective door 10 is movably connected to the surface of the winding rod 6 and can be raised and lowered along the opening direction of the winding box 5 to close or open the opening on the front of the metal bracket 1.

[0063] The controller controls the motor 9 to drive the transparent protective door 10 to descend and close based on the detection signal of the ammonia detector 26, controls the exhaust fan 11 and the blower 17 to start exhausting, and controls the water inlet pipe 25 to spray water, forming a multi-level linkage protection of detection, sealing, exhaust, filtration and spraying.

[0064] In some specific embodiments, the transmission mechanism includes a worm gear 7 and a worm 8. The worm gear 7 is fixedly installed on the surface of the winding rod 6, and the worm 8 meshes with the surface of the worm gear 7. The output shaft of the motor 9 is fixedly connected to the bottom of the worm 8, and the top of the worm 8 is movably connected to the surface of the inner wall of the winding box 5 through a bearing seat. When the ammonia detector 26 detects that the ammonia concentration exceeds the standard, the controller starts the motor 9 to drive the worm 8 to rotate, which in turn drives the worm gear 7 and the winding rod 6 to rotate, causing the transparent protective door 10 to descend and close the protective shed.

[0065] In this embodiment, please refer to Figure 4 and Figure 8 The transmission mechanism includes a worm gear 7 and a worm 8. The worm gear 7 is fixedly mounted on the surface of the winding rod 6, the worm 8 meshes with the surface of the worm gear 7, the output shaft of the motor 9 is fixedly connected to the bottom of the worm 8, and the top of the worm 8 is movably connected to the surface of the inner wall of the winding box 5 through a bearing seat.

[0066] When the ammonia detector 26 detects that the ammonia concentration exceeds the standard, the controller starts the motor 9 to drive the worm gear 8 to rotate. The worm gear 8 drives the worm wheel 7 to rotate, and the worm wheel 7 drives the winding rod 6 to rotate synchronously, causing the transparent protective door 10 to descend, unfold, and close the protective canopy. The worm gear transmission mechanism has a self-locking characteristic. When the motor 9 stops, the transparent protective door 10 remains in its current position and will not rise or fall on its own due to gravity or external forces, ensuring the stability of the closed state.

[0067] After the inspection is completed, the controller controls the motor 9 to rotate in the opposite direction, driving the worm 8, worm wheel 7 and winding rod 6 to rotate in the opposite direction, winding up the transparent protective door 10 and opening the front opening of the protective shed to facilitate the entry and exit of the equipment.

[0068] In some specific embodiments, a plastic plate 13 is movably connected to the inner wall surface of the opening 12 via a pivot pin. A baffle 14 is fixedly installed on the top of the plastic plate 13, and the baffle 14 is located on the side of the plastic plate 13 away from the pivot pin connection end. The plastic plate 13 remains horizontally closed to the opening 12 under the action of gravity, and flips upward to open under the action of the exhaust fan 11.

[0069] In this embodiment, please refer to Figure 3 and Figure 6 The top plate 3 has multiple openings 12 at its top. The inner wall of each opening 12 is movably connected to a plastic plate 13 via a pivot pin. The plastic plate 13 can rotate up and down around the pivot pin. A stop bar 14 is fixedly installed on the top of the plastic plate 13. The stop bar 14 is located on the side of the plastic plate 13 away from the pivot pin connection end and is used to limit the rotation angle of the plastic plate 13.

[0070] When the exhaust fan 11 is not in operation, the plastic panel 13 remains horizontal under its own weight, sealing the opening 12 and preventing external dust from entering the protective shed. When the exhaust fan 11 starts to draw air, the airflow acts upward on the plastic panel 13, overcoming gravity and causing it to flip upward and open, allowing the gas inside the shed to be discharged through the opening 12. The baffle 14 engages with the inner wall of the exhaust hood 15 to limit the flipping angle of the plastic panel 13 and prevent excessive flipping that could cause damage.

[0071] When the exhaust fan 11 stops, the plastic plate 13 automatically falls back to close the opening 12 under the action of gravity, without the need for additional power or control, thus achieving passive self-sealing.

[0072] In some specific embodiments, the interior of the filter box 16, from the input end to the output end, is sequentially arranged with a polyester fiber mesh 18, granular activated carbon 19, a type 4A molecular sieve 20, and a high-efficiency meltblown fabric 21. A sealing plate 22 is movably connected to the top of the filter box 16 via a pivot pin, facilitating opening and replacement of the filter material. The polyester fiber mesh 18 is used to filter large particulate impurities, the granular activated carbon 19 is used to adsorb ammonia molecules, the type 4A molecular sieve 20 is used to selectively adsorb small molecule gases, and the high-efficiency meltblown fabric 21 is used for fine filtration of residual particles.

[0073] In this embodiment, a polyester fiber mesh 18 is disposed at the air inlet of the filter box 16 to filter large particulate impurities and dust in the air, protecting the downstream filter material. Granular activated carbon 19 is disposed downstream of the polyester fiber mesh 18, utilizing the porous structure of the activated carbon to adsorb ammonia molecules. A molecular sieve 20 is disposed downstream of the granular activated carbon 19, utilizing the pore size of the molecular sieve to selectively adsorb water molecules and small molecule gases, improving ammonia adsorption efficiency and preventing activated carbon saturation. High-efficiency meltblown fabric 21 is disposed at the air outlet of the filter box 16 to finely filter residual particles, ensuring clean exhaust gas.

[0074] One end of the filter box 16 is connected to the exhaust hood 15, and the fan 17 is connected to the other end of the filter box 16. Under the action of the fan 17, the gas inside the shed is discharged after passing through four stages of filtration and purification.

[0075] In some specific embodiments, multiple metal crossbars 2 are fixedly installed in parallel between the tops of two metal supports 1. A top plate 3 is laid above the multiple metal crossbars 2. Wall panels 4 are fixedly installed on both sides and the back of the metal supports 1. The air inlet is located at the lower part of the back wall panel 4. The air inlet and the exhaust fan 11 form an upward airflow channel, creating a crossflow field with the spray direction of the spray system. It should be noted that a wall is provided on the back of the metal supports 1, and the air inlet is located at the lower part of the back wall.

[0076] In this embodiment, when the exhaust fan 11 is started, fresh outside air enters the protective shed from the lower air inlet, flows upward carrying ammonia gas and is discharged through the outlet 12, forming a bottom-in, top-out airflow organization. The spray nozzles 24 of the spray system spray water downward, forming a water mist curtain from top to bottom. The airflow direction and the spraying direction form a cross flow field, enhancing gas-liquid contact and improving ammonia absorption efficiency.

[0077] In some specific embodiments, multiple square tubes 23 are fixedly installed in parallel at the bottom of the metal crossbar 2. The bottom of each square tube 23 is connected to multiple nozzles 24. A solenoid valve is installed on the water inlet pipe 25. The controller controls the solenoid valve to open according to the detection signal of the ammonia detector 26, so that water passes through the square tube 23 and the nozzles 24 to form a water mist curtain. The spraying system is linked with the exhaust filtration system. After the water mist absorbs ammonia, it is discharged through the exhaust filtration system.

[0078] In this embodiment, please refer to Figure 2 and Figure 7 Multiple square tubes 23 are fixedly installed in parallel at the bottom of the metal crossbar 2. Each square tube 23 has multiple nozzles 24 connected to its bottom, with the nozzles 24 facing downwards. A water inlet pipe 25 is connected to the surface of the square tube 23, and the water inlet pipe 25 is connected to an external water source. A solenoid valve is installed on the water inlet pipe 25.

[0079] The controller opens the solenoid valve based on the detection signal from the ammonia detector 26. Water from an external water source enters the square pipe 23 through the inlet pipe 25 and is sprayed out from multiple nozzles 24 to form a water mist curtain that evenly covers the interior space of the protective shed. The water mist absorbs the ammonia gas upon contact with it. The absorbed gas-liquid mixture flows upward under the action of the exhaust fan 11 and is discharged through the exhaust filtration system.

[0080] The spray system works in conjunction with the exhaust filtration system. After the water mist adsorbs ammonia, it is further purified by the four-stage filtration of the exhaust filtration system, achieving a synergistic effect of physical absorption and chemical adsorption.

[0081] In some specific embodiments, the ammonia detector 26 is located in the middle of the inner side of the metal support 1 to monitor the ammonia concentration inside the protective shed in real time; when the ammonia concentration exceeds the first preset threshold, the controller starts the transparent protective door 10 to descend and the exhaust filtration system to work; when the ammonia concentration exceeds the second preset threshold, the controller starts the spray system; when the ammonia concentration exceeds the third preset threshold, the controller starts the audible and visual alarm device; the first preset threshold is less than the second preset threshold, and the second preset threshold is less than the third preset threshold.

[0082] In this embodiment, please refer to Figure 1 and Figure 8 The ammonia detector 26 is located in the middle of the inner side of the metal support 1, in the middle of the height direction of the internal space of the protective shed, and is used to monitor the ammonia concentration in the protective shed in real time. The controller has three preset thresholds: a first preset threshold, a second preset threshold, and a third preset threshold, and the first preset threshold is less than the second preset threshold, and the second preset threshold is less than the third preset threshold.

[0083] When the ammonia concentration exceeds the first preset threshold, the controller activates the transparent protective door 10 to descend and close the protective shed, and simultaneously starts the exhaust fan 11 and the blower 17 to filter the exhaust. At this time, the spray system does not start to avoid over-response.

[0084] When the ammonia concentration exceeds the second preset threshold, the controller activates the spray system to enhance the ammonia absorption and purification capacity, based on the exhaust filtration.

[0085] When the ammonia concentration exceeds the third preset threshold, the controller activates the audible and visual alarm device to prompt on-site personnel to evacuate, and continues to exhaust and filter the gas, awaiting manual intervention.

[0086] The three-level threshold control strategy responds in stages according to the severity of the leak, minimizing the impact on detection operations and improving the continuity of detection while ensuring safety.

[0087] Further, Example 1: Specific application of three-level threshold control

[0088] In the sealing test of a certain type of ammonia dual-fuel main engine injector, the protective shed and control method of this invention were used. The internal dimensions of the protective shed are 5 meters long, 3 meters wide, and 3 meters high, with a volume of 45 cubic meters.

[0089] The first preset threshold is set at 25 ppm (parts per million). This value is determined based on the fact that the olfactory detection threshold of ammonia is approximately 50 ppm. Below 25 ppm, the protective system can be activated before the operator can perceive the ammonia odor, providing early warning protection. When the ammonia detector detects a concentration of 25 ppm inside the enclosure, the controller immediately starts the motor, driving the transparent protective door to close within 5 seconds. Simultaneously, the exhaust fan and blower are activated, with an exhaust airflow of 10 cubic meters per minute, creating a closed negative pressure exhaust state.

[0090] The second preset threshold is set at 100 ppm. This value is determined based on the following: the time-weighted average (TWA) tolerance concentration of ammonia is 25 ppm, the short-term exposure limit (STEL) is 35 ppm, and 100 ppm is far below the acute toxicity exposure limit (300 ppm), but indicates that the leakage has exceeded the range of minor leakage. When the concentration continues to rise and reaches 100 ppm under closed exhaust conditions, the controller activates the spray system, the inlet solenoid valve opens, and water is sprayed from the nozzles at a pressure of 0.2 MPa, forming a water mist curtain with a particle size of 50 to 100 micrometers, which fully contacts and absorbs the ammonia.

[0091] The third preset threshold is set at 200 ppm. This value is determined based on the fact that a concentration approaching the Immediately Threatened Pathogen Level (IDLH, 300 ppm) indicates a serious leak or that the containment ventilation and sprinkler systems have failed to effectively control the leak. When the concentration reaches 200 ppm, or if the concentration remains above 100 ppm after a preset 10-minute period, the controller activates an audible and visual alarm, flashing a red warning light and emitting a buzzer alarm to alert personnel to evacuate immediately. Simultaneously, the controller keeps the exhaust fans, blowers, and sprinkler systems running continuously, awaiting manual intervention by professionals via the control panel or remote monitoring center.

[0092] The ratio between the thresholds is 25:100:200, or 1:4:8. This ratio ensures that the first-level response has sufficient warning time, the second-level response provides enhanced protection, and the third-level response serves as the last line of defense. A reasonable gradient is formed between the three levels to avoid responses that are too dense or too sparse.

[0093] In some specific embodiments, a communication device is also included;

[0094] When the ammonia detector 26 stops emitting alarm signals, the controller records the location, time, peak concentration, and handling measures of the current leak event, and generates a maintenance report which is sent to the monitoring center via the communication device.

[0095] In this embodiment, please refer to Figure 8 The invention also includes a communication device electrically connected to the controller. When the ammonia detector 26 stops emitting an alarm signal, it indicates that the leak has been controlled or eliminated. The controller automatically records relevant information about the current leak event, including the location, time of occurrence, peak concentration, duration, and measures taken.

[0096] The controller generates a maintenance report based on the recorded data, detailing the leakage incident and its impact assessment, and sends the report to a remote monitoring center via communication devices. The monitoring center can then schedule maintenance personnel to conduct inspections and repairs based on the report, achieving closed-loop management and traceability of leakage incidents.

[0097] In another embodiment, reference Figure 9 The control method shown is for a protective shed to prevent ammonia leakage during the detection of a dual-fuel ammonia main engine. Applied to the aforementioned protective shed, it includes:

[0098] S1. Real-time acquisition of signals from ammonia detector 26 to monitor ammonia concentration inside the protective shed;

[0099] The system collects signals from an ammonia detector in real time to monitor the ammonia concentration inside the protective shed. The ammonia detector is positioned in the middle of the inner side of a metal support frame, continuously detecting the ammonia concentration in the air inside the shed and transmitting the detection signal to the controller in real time. The controller processes the detection signal, calculates the current ammonia concentration value, and compares it with a preset threshold.

[0100] S2. If the ammonia detector 26 detects that the ammonia concentration exceeds the first preset threshold, the motor 9 is started to drive the transparent protective door 10 to descend and close the protective shed, and the exhaust fan 11 and the blower 17 are started at the same time to filter the exhaust.

[0101] If the ammonia detector detects that the ammonia concentration exceeds the first preset threshold, the motor is activated to lower the transparent protective door to close the protective shed. Simultaneously, the exhaust fan and blower are started for exhaust filtration. When the ammonia concentration reaches the first preset threshold but does not exceed the second preset threshold, the controller sends a start signal to the motor. The motor drives the worm gear to rotate, which in turn drives the worm wheel and winding rod to rotate. The transparent protective door descends and unfolds from the winding box, closing the open opening on the front of the metal support. At the same time, the controller starts the exhaust fan and blower. The exhaust fan creates a suction airflow at the top of the top plate, causing the plastic panel to flip upwards and open the vent. The gas inside the protective shed enters the filter box through the vent and exhaust hood, passing through a four-stage filtration process: polyester fiber mesh, granular activated carbon, molecular sieve, and high-efficiency meltblown fabric, before being discharged. During this stage, only physical sealing and exhaust filtration are performed; the spray system is not activated.

[0102] S3. If the ammonia concentration exceeds the second preset threshold, the solenoid valve of the water inlet pipe 25 will be opened for spraying.

[0103] If the ammonia concentration exceeds the second preset threshold, the solenoid valve on the water inlet pipe will open to initiate spraying. When the ammonia concentration continues to rise and exceeds the second preset threshold, the controller sends an opening signal to the solenoid valve on the water inlet pipe. The solenoid valve opens, and water from the external water source flows into the square pipe, spraying downwards from multiple nozzles at the bottom of the square pipe to form a uniform water mist curtain. The water mist comes into full contact with the ammonia inside the shed, absorbing the ammonia to form a gas-liquid mixture. Under the suction of the exhaust fan, this mixture flows upwards and enters the exhaust filtration system through the inlet for further purification before being discharged.

[0104] S4. If the ammonia concentration drops to a safe range after the preset time, stop spraying and exhausting, and raise the transparent protective door 10.

[0105] If the ammonia concentration drops to a safe range after a preset time, the spraying and exhaust will stop, and the transparent protective door will be raised. The controller continuously monitors changes in ammonia concentration. If, after a preset time has elapsed since the start of the response, the ammonia concentration has dropped below the first preset threshold and remained within a safe range, the controller first closes the solenoid valve on the water inlet pipe to stop spraying, then shuts off the fan and exhaust fan to stop exhausting, and finally starts the motor to rotate in reverse, driving the transparent protective door to rise and retract into the rewind box, opening the front opening of the protective canopy, and resuming normal detection operations.

[0106] Furthermore, Example 2: Dynamic Determination and Adjustment of Preset Time

[0107] The preset time is determined based on a comprehensive calculation of the protective shed volume, exhaust fan air volume, and safety factor. The basic calculation formula is: Where t is the preset time (minutes), V is the volume of the protective shed (cubic meters), Q is the effective air volume of the exhaust fan (cubic meters per minute), and k is the safety factor.

[0108] Taking a protective shed with a volume of V=50 cubic meters and an exhaust fan volume of Q=10 cubic meters per minute as an example, with a safety factor k of 2.0 (considering factors such as filter resistance and leakage rate fluctuations), the preset time t=2.0×50 / 10=10 minutes.

[0109] The physical meaning of this preset time is as follows: In a closed state, the exhaust fan ventilates a 50 cubic meter space at a flow rate of 10 cubic meters per minute, theoretically resulting in 2 air changes (k=2.0), which can reduce the ammonia concentration in the shed to approximately 13.5% of the initial concentration (assuming a purification efficiency of 100%). Considering that the actual purification efficiency is approximately 80% to 90%, after 10 minutes, the ammonia concentration of 200 ppm can be reduced to 40 ppm to 50 ppm, which is lower than the second preset threshold, proving the rationality of the preset time.

[0110] The preset time is dynamically adjusted as follows: When the ambient temperature is below 10 degrees Celsius, the ammonia molecule movement rate decreases, the adsorption efficiency increases, the safety factor k can be adjusted to 1.5, and the preset time is shortened to 7.5 minutes; when the ambient temperature is above 30 degrees Celsius, the ammonia volatilization rate increases, the safety factor k is adjusted to 2.5, and the preset time is extended to 12.5 minutes. The controller has a built-in temperature sensor that automatically adjusts the preset time according to the real-time temperature.

[0111] In actual operation, if the ammonia concentration drops below 25 ppm after a preset time, the controller determines that the leak has been controlled, stops the spraying and venting, raises the transparent protective door, resumes normal detection operations, and records the event as "minor leak - self-recovered". If the concentration is still above 100 ppm after a preset time, the controller determines that it is a continuous or serious leak, activates the audible and visual alarm, records it as "serious leak - manual handling required", and sends a report to the monitoring center via the communication device.

[0112] S5. If the ammonia concentration continues to exceed the third preset threshold within a preset time, an audible and visual alarm will be activated and the exhaust filtration will continue until manual intervention is required.

[0113] If the ammonia concentration continues to exceed the third preset threshold within a preset time period, an audible and visual alarm will be activated, and exhaust filtration will continue until manual intervention. When the ammonia concentration exceeds the third preset threshold, or if the ammonia concentration remains above the second preset threshold after a preset response time, the controller will activate the audible and visual alarm device, issuing an audible and visual warning signal to prompt on-site personnel to evacuate immediately. Simultaneously, the controller will keep the exhaust fan, blower, and sprinkler system running continuously for forced exhaust and sprinkler absorption until manual intervention is performed by the operator via manual switch or remote command, or until the ammonia concentration drops to a safe range and automatically resumes operation.

[0114] In another embodiment, an ammonia dual-fuel main engine testing system includes the aforementioned protective shed for preventing ammonia leakage during testing. This testing system is used for various performance tests during the production process of the ammonia dual-fuel main engine, including fuel injection system testing, combustion performance testing, and sealing testing. During testing, the ammonia dual-fuel main engine is placed inside the protective shed, with the transparent protective door raised for easy operation. If an ammonia leak occurs during testing, the protective shed automatically activates multi-level linkage protection to ensure operational safety.

[0115] Working principle of the invention

[0116] Please see Figures 1 to 8 The working principle of the protective canopy for preventing ammonia leakage in the dual-fuel ammonia main engine detection system of the present invention is as follows:

[0117] Normal testing status: The transparent protective door 10 is in the raised position, the front opening of the metal support 1 is open, and the dual-fuel ammonia unit can enter and exit the protective shed through the opening. The ammonia detector 26 monitors the ammonia concentration inside the shed in real time, and all systems are in standby mode at this time.

[0118] Initial Response Status: When the ammonia detector 26 detects that the ammonia concentration exceeds the first preset threshold, it indicates a minor leak. The controller immediately initiates the initial response: the motor 9 drives the worm gear 8 to rotate, which in turn drives the winding rod 6 to rotate via the worm wheel 7. The transparent protective door 10 quickly descends to close the open front of the protective shed, forming a closed space to restrict the diffusion of ammonia. Simultaneously, the exhaust fan 11 and blower 17 start, and the plastic panel 13 flips open under the action of airflow. The gas inside the shed enters the filter box 16 through the vent 12 and exhaust hood 15, and is then filtered and purified through four stages: polyester fiber mesh 18, granular activated carbon 19, molecular sieve 20, and high-efficiency meltblown fabric 21 before being discharged. The spray system is not activated during this stage to avoid over-response.

[0119] Intermediate Response State: If the ammonia concentration continues to rise above the second preset threshold, indicating a large leak or insufficient filtration and purification capacity, the controller initiates an intermediate response: the solenoid valve of the water inlet pipe 25 is opened, and water is sprayed from the nozzle 24 through the square pipe 23 to form a water mist curtain. The water mist fully contacts and absorbs the ammonia from top to bottom. The absorbed gas-liquid mixture flows upward under the action of the exhaust fan 11 and is further purified and discharged through the exhaust filtration system. The spraying and exhaust filtration work together to enhance the ammonia removal capacity.

[0120] Advanced Response Status: If the ammonia concentration continues to rise above the third preset threshold, it indicates a serious leak. The controller will activate the advanced response: activate the audible and visual alarm device to prompt on-site personnel to evacuate immediately, while continuously ventilating, filtering, and spraying air, awaiting manual intervention by professional personnel.

[0121] Recovery Status: Once the ammonia concentration drops to a safe range and remains within a preset time, the controller determines that the leak has been controlled, stops spraying and venting, the plastic plate 13 automatically falls back to close the opening 12 under gravity, the transparent protective door 10 rises, and normal detection operations resume. The controller records the leak event information and generates a maintenance report, which is then sent to the monitoring center.

[0122] Airflow organization principle: The air inlet is located at the lower part of the back wall of the protective canopy, and the exhaust fan 11 is located at the upper part of the top plate 3, forming an upward airflow channel. The spray nozzles 24 of the spray system spray water downwards, forming a downward water mist curtain. The airflow direction and the spray direction form a cross flow field, prolonging the gas-liquid contact time and improving the ammonia absorption efficiency. The four-stage filtration system is located at the end of the exhaust channel to deeply purify the exhaust gas and prevent environmental pollution.

[0123] Multi-level linkage principle: The five major systems—detection, sealing, exhaust, filtration, and spraying—are intelligently linked through a controller. The rapid closure of the transparent protective door 10 forms the first line of defense, limiting the diffusion range of ammonia gas; the exhaust filtration system creates negative pressure for extraction and purification, forming the second line of defense; and the spraying system absorbs water mist, forming the third line of defense. Three-level threshold control ensures the system responds accurately according to the degree of leakage, maximizing the continuity of detection operations while ensuring safety.

[0124] Example 3: Precise Timing of Multi-Level Linkage Control

[0125] During a test of the high-pressure oil pump of a dual-fuel ammonia main unit, a minor ammonia leak occurred. The ammonia detector detected a concentration of 25 ppm at time T0 and immediately sent an alarm signal to the controller. The controller completed signal processing and judgment within T0+0.1 seconds and simultaneously sent start commands to the motor controller and exhaust fan controller.

[0126] The motor starts rotating at T0+0.5 seconds, driving the winding rod to rotate via worm gear and worm wheel transmission, and the transparent protective door begins to descend. The transparent protective door descends at a speed of 0.5 meters per second, the protective canopy is 3 meters high, and it takes 6 seconds to descend and completely close, that is, to complete the closure at T0+6.5 seconds.

[0127] The exhaust fan receives the start signal at T0+0.3 seconds (slightly earlier than the motor, considering electrical response time), and the fan impeller reaches its rated speed at T0+1.0 seconds, starting to draw air. At this time, the transparent protective door has descended about 0.5 meters, not yet completely closed, but has already formed partial obstruction. By T0+6.5 seconds, when the transparent protective door is completely closed, the exhaust fan has established a stable airflow, and the plastic panel flips open under the action of the airflow, forming a closed exhaust state.

[0128] The above timing design ensures that the time difference between the closing of the transparent protective door and the start of the exhaust fan does not exceed 3 seconds (actually 0.8 seconds), avoiding the risk of leakage caused by a brief increase in ammonia pressure inside the shed at the moment of closing; the exhaust fan starts before the transparent protective door is completely closed, establishing airflow organization in advance and reducing the residence time of ammonia in the enclosed space.

[0129] If the ammonia concentration continues to rise to the second preset threshold of 100 ppm, the controller will activate the spray system at time T100. To evaluate the exhaust filtration effect, a 5-second delay is set, and the inlet water pipe solenoid valve will open at T100+5 seconds. During this delay, if the exhaust filtration causes a significant decrease in concentration (e.g., a decrease of more than 10 ppm per minute), the spray system activation will be canceled to avoid over-response; if the concentration continues to rise or remains high, the spray system activation will be confirmed.

[0130] After the spray system is activated, the exhaust fan airflow automatically increases by 20% (from 10 cubic meters per minute to 12 cubic meters per minute), enhancing the water mist carrying capacity and creating a synergistic effect between the spray and exhaust systems. This airflow increase is achieved through a frequency converter; the controller sends an analog signal to the frequency converter, and the airflow adjustment is completed within 3 seconds.

[0131] Example 4: Mechanical Design of Gravity-Based Self-Enclosed Plastic Sheet

[0132] The opening is rectangular, measuring 0.4 meters long and 0.3 meters wide, with a cross-sectional area of ​​0.12 square meters. The plastic sheet is made of polycarbonate, with a density of 1.3 grams per cubic centimeter and a thickness of 3 millimeters. Its dimensions are 0.42 meters long and 0.32 meters wide (slightly larger than the opening), and its mass is 0.42 meters × 0.32 meters × 0.003 meters × 1300 kilograms per cubic meter = 0.52 kilograms.

[0133] The plastic sheet is connected to the edge of the opening by a stainless steel pin with a diameter of 8 mm. The pin is located on the long side of the plastic sheet, 20 mm from the edge. The center of gravity of the plastic sheet is located at the geometric center, which is 0.21 meters (half the width of the sheet) minus 0.02 meters (pin offset), or 0.19 meters, from the center line of the pin.

[0134] Calculation of gravitational torque: Gravity = 0.52 kg × 9.8 m / s² = 5.1 N, gravitational torque = 5.1 N × 0.19 m = 0.97 Nm. This torque causes the plastic plate to tend to flip downwards around the pivot pin. When the exhaust fan is not working, the plastic plate remains horizontal under the action of gravitational torque, sealing the opening.

[0135] When the exhaust fan starts, a negative pressure is created on the lower surface of the plastic plate, while the upper surface remains at atmospheric pressure, resulting in an upward pressure difference. When the exhaust fan's airflow is 10 cubic meters per minute, the inlet air velocity is approximately 1.4 meters per second. Based on Bernoulli's equation, the pressure difference between the upper and lower surfaces of the plastic plate is estimated to be approximately 50 Pascals. The upward force generated by this pressure difference is 50 Pascals × 0.12 square meters = 6 Newtons, and the torque is 6 Newtons × 0.19 meters = 1.14 Newton-meters.

[0136] The airflow opening torque (1.14 Nm > gravitational torque (0.97 Nm)) causes the plastic panel to flip upwards and open. The flipping angle is limited to 70 degrees by the baffle bar. At this time, the plastic panel makes a 70-degree angle with the horizontal plane, allowing airflow to pass through while maintaining the open state. The baffle bar is an aluminum alloy strip with a width of 15 mm and a thickness of 5 mm, which is fixed to the upper surface of the plastic panel with screws and forms a mechanical limit when it contacts the inner wall of the exhaust hood.

[0137] When the exhaust fan stops, the pressure difference disappears, the airflow opening torque returns to zero, and the gravitational torque causes the plastic plate to fall back. It takes about 0.5 seconds to flip from 70 degrees to a horizontal position, achieving rapid self-sealing. An oil-impregnated bearing is installed at the pivot pin, with a frictional torque of less than 0.1 Newton-meters, ensuring smooth flipping.

[0138] Example 5: Selection and Combination of Four-Stage Filter Materials

[0139] The filter box is made of stainless steel and measures 0.6 meters long, 0.4 meters wide, and 0.5 meters high, with an internal effective volume of 0.12 cubic meters. Inside the filter box, four layers of filter material are arranged sequentially from the air inlet to the air outlet, with stainless steel mesh partitions spaced 20 millimeters apart between each layer to ensure even airflow distribution.

[0140] The first layer is a 10 mm thick polyester fiber mesh with an 80 micrometer pore size and a dust holding capacity of 500 grams per square meter. This layer primarily filters airborne dust particles and fibrous impurities, protecting the downstream activated carbon from clogging. The polyester fiber mesh is fixed with a detachable frame and should be replaced every 3 months or when the pressure drop exceeds 100 Pascals.

[0141] The second layer is granular activated carbon, 80 mm thick, made from coconut shell activated carbon. It has an iodine adsorption value of 900 mg / g, a specific surface area of ​​1100 m² / g, and a dynamic ammonia adsorption capacity of 12% (mass fraction). The activated carbon packing density is 0.5 g / cm³, and the total mass of this layer is 0.6 m × 0.4 m × 0.08 m × 500 kg / m³ = 9.6 kg. The theoretical ammonia adsorption capacity is 1.15 kg. Under conditions of an ammonia concentration of 200 ppm and an airflow of 10 m³ / min, the activated carbon layer penetration time is approximately 30 minutes, meeting the requirements for handling leaks.

[0142] The third layer is a type 4A molecular sieve, 40 mm thick, with a pore size of 4 angstroms (0.4 nm), which selectively adsorbs water and ammonia molecules. The molecular sieve maintains its ammonia adsorption capacity even at 60% relative humidity, while activated carbon's adsorption efficiency decreases in high humidity environments; the two complement each other. After filling, the molecular sieve requires activation at 300 degrees Celsius to restore its adsorption performance.

[0143] The fourth layer is a high-efficiency meltblown fabric, 1 mm thick, with a filtration efficiency of 99.5% at 0.3 microns. It is used to intercept dust particles that may be generated by activated carbon and molecular sieves, ensuring clean exhaust gas. The meltblown fabric is made of polypropylene and undergoes electrostatic electret treatment to enhance its adsorption capacity for particles.

[0144] The total airflow resistance of the four-layer material is controlled at around 800 Pascals, matching the fan head to ensure a stable system airflow of 10 cubic meters per minute. A sealing plate is installed on the top of the filter box, connected by a quick-opening hinge, so that the pipeline does not need to be disassembled when replacing the filter material, reducing maintenance time to less than 15 minutes.

[0145] Example 6: Design and Effect Verification of Cross Flow Field

[0146] Two rectangular air inlets are installed at the lower part of the back wall of the protective canopy, each measuring 0.3 meters long and 0.2 meters high, with a total area of ​​0.12 square meters. Louvered grilles are installed inside the air inlets to prevent foreign objects from entering and to guide airflow close to the ground. An exhaust fan is installed on the ceiling, with a total ventilation area of ​​0.08 square meters. The ratio of the air inlet area to the exhaust fan ventilation area is 1.5 to ensure smooth airflow and prevent airflow throttling.

[0147] The sprinkler system consists of four square tubes arranged parallel to each other at the bottom of a metal crossbar, spaced 1 meter apart. Each tube has five nozzles at its bottom, for a total of 20 nozzles. The nozzles are pressure atomizers with a working pressure of 0.2 MPa, a flow rate of 2 liters per minute per nozzle, and a total flow rate of 40 liters per minute. The nozzles spray downwards at a 75-degree cone angle, forming a 1.5-meter diameter coverage circle at a height of 2 meters. Adjacent nozzles overlap by 30% to ensure uniform coverage within the shed.

[0148] The exhaust fan draws air in, creating an upward vertical airflow with a wind speed of approximately 0.3 meters per second. The sprayed water mist moves downward with an initial velocity of approximately 5 meters per second, gradually decelerating under gravity, reaching a speed of approximately 2 meters per second when it meets the upward airflow. The relative velocity between the gas and liquid is approximately 2.3 meters per second, creating a crossflow field.

[0149] In the cross-flow field, ammonia molecules move with the rising airflow and come into full contact with the falling water droplets. The water droplets have a diameter of 50 to 100 micrometers, a large specific surface area, and high contact efficiency with ammonia. Ammonia dissolves in water to form ammonia water, which is carried downward by the water droplets, accumulates at the bottom, and is discharged through a drain or enters the exhaust filtration system for further treatment with the airflow.

[0150] Comparative tests show that, under the same leakage conditions, the ammonia removal rate is 70% when only the exhaust filter is turned on, 65% when only the spray is turned on, and the removal rate of the cross-flow field design (exhaust + spray synergy) reaches over 90%, with a significant synergistic effect.

[0151] Example 7: Complete Application of the Control Method

[0152] A shipyard used the protective canopy of this invention to conduct fuel system sealing tests on ammonia dual-fuel main engines before they left the factory. Before the test, the transparent protective door was raised, and the main engine was placed inside the protective canopy through the front opening. The operators closed the isolation door outside the canopy and monitored the test process through the observation window.

[0153] Ten minutes after the start of the test, a slight leak occurred at the high-pressure oil pipe interface of the main unit. The ammonia detector detected a concentration rise to 28 ppm, exceeding the first preset threshold of 25 ppm. The controller completed the judgment within 0.5 seconds and simultaneously started the motor and exhaust fan. The transparent protective door closed completely within 6 seconds, the exhaust fan established an airflow of 10 cubic meters per minute, and the plastic panel flipped open, forming a closed exhaust state. The operator observed the protective door automatically closing in the monitoring room and knew that a leak had occurred, but could still observe the situation inside the shed through the transparent protective door.

[0154] After the venting was closed for 3 minutes, the concentration dropped to 22 ppm, below the first preset threshold. However, after 5 minutes, the leak point expanded, and the concentration rose again to 105 ppm, exceeding the second preset threshold of 100 ppm. After assessing the downward trend over the first 3 minutes, the controller determined that enhanced protection needed to be activated. After a 5-second delay (assessment window) following the concentration reaching 105 ppm, and confirming a continued rise in concentration, the sprinkler system was activated. Once the water mist curtain formed, the concentration increase slowed, dropping to 80 ppm after 8 minutes.

[0155] After 15 minutes of coordinated operation of the spraying and exhaust systems, the concentration dropped to 20 ppm, below the first preset threshold. The controller continued operating for 5 minutes to confirm stability, then stopped spraying, followed by exhaust after 3 minutes, and the plastic panel automatically fell back to seal the opening. Two minutes later, the transparent protective door rose, and the testing operation automatically resumed. The entire incident lasted 35 minutes without interrupting the testing process or causing personnel exposure.

[0156] The controller automatically generated an event report: the incident occurred in area A of the protective shed at 14:23, with a peak concentration of 105 ppm and a duration of 35 minutes. The measures taken were sealing off the vents and spraying water. The recovery method was automatic recovery. Recommended maintenance items included checking the sealing ring of the main unit's high-pressure oil pipe interface. The report was sent to the plant-level monitoring center via the 4G network. Maintenance personnel addressed the leak point after the inspection was completed.

[0157] Example 8: Communication Devices and Remote Monitoring

[0158] The communication device uses an industrial-grade 4G router, supports the MQTT IoT protocol, and connects to the controller via an RS485 bus. When the ammonia detector stops emitting alarm signals, the controller organizes the event information, including: event number (automatically generated, in the format of year, month, day + serial number, such as 20250115001), location of occurrence (protective shed number), start time, end time, peak concentration, duration, measures taken (combination code of sealing / ventilation / spraying / alarm), and recovery method (automatic recovery / manual recovery).

[0159] The above information is used to generate a JSON-formatted maintenance report according to a preset format, which is then uploaded to the cloud server via a 4G network. After receiving the report, the monitoring software at the plant-level monitoring center marks the location of the event on an electronic map, displays the event details, and automatically assigns maintenance priorities based on peak concentration and duration: events with peak concentrations exceeding 100 ppm or lasting longer than 30 minutes are marked as urgent and pushed to the maintenance foreman's mobile terminal; other events are marked as general and added to the routine maintenance queue.

[0160] The monitoring center can remotely access the controller to view ammonia concentration, system operating status, and historical event records in real time. In emergencies, the monitoring center can remotely start or stop the systems, enabling remote intervention. The controller locally stores the 100 most recent event records, which are temporarily stored locally during network interruptions and automatically re-uploaded upon network recovery to ensure data integrity.

[0161] By adopting the above-disclosed technical solution of this invention, the following beneficial effects are obtained:

[0162] The protective canopy and control method for preventing ammonia leakage in dual-fuel main engine detection provided by this invention have the following advantages compared with the prior art:

[0163] First, the present invention uses a metal bracket, wall panels, and top panel to form the protective shed body, and with the help of a transparent protective door system, it can form a closed space during the inspection operation, effectively limiting the diffusion range of ammonia gas, and solving the technical problem that open treatment cannot be effectively sealed.

[0164] Secondly, the present invention uses a worm gear transmission mechanism to drive the transparent protective door. By utilizing the self-locking characteristics of the worm gear, the protective door is ensured to remain stable in the closed state, while achieving rapid response, thus resolving the technical contradiction between closing and rapid opening and closing.

[0165] Third, the present invention has an opening in the top plate and forms a gravity self-sealing structure through a plastic plate and baffles. The opening is automatically closed when the exhaust fan is not working and automatically opened when exhausting, without the need for additional power and control, thus simplifying the system structure.

[0166] Fourth, the present invention employs a four-stage filtration combination, which sets up polyester fiber mesh, granular activated carbon, molecular sieve and high-efficiency meltblown cloth in a specific order to form a gradient filtration, thereby improving the ammonia purification efficiency and reducing water consumption.

[0167] Fifth, the present invention adopts a three-level threshold control strategy, which responds in stages according to the ammonia concentration, avoiding over-response or under-response caused by a single threshold, and improving the continuity of detection operations while ensuring safety.

[0168] Sixth, this invention achieves multi-level linkage of detection, sealing, exhaust, filtration, and spraying to form a complete protection system. The coordinated operation of each system improves the overall protection effect.

[0169] Seventh, the present invention places the spraying system at the bottom of the metal crossbar, forming a cross flow field with the exhaust system, which enhances the contact between ammonia gas and sprayed water mist and improves absorption efficiency.

[0170] Eighth, the present invention is equipped with a communication device that can automatically record leakage events and generate maintenance reports, thereby realizing intelligent management and traceability.

[0171] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A protective shed for preventing ammonia leakage during testing of a dual-fuel ammonia main engine, characterized in that, This includes the protective canopy itself, a transparent protective door system, an exhaust filtration system, a sprinkler system, and an ammonia detection system; The protective shed body includes a metal frame (1), a metal crossbar (2), a top plate (3) and a wall panel (4). The metal crossbar (2) is fixedly installed on the top of the metal frame (1), the top plate (3) is set on the top of the metal crossbar (2), and the wall panel (4) is fixedly installed on both sides of the metal frame (1). The front of the metal frame (1) is an open opening. The transparent protective door system includes a winding box (5), a winding rod (6), a transmission mechanism, a transparent protective door (10), and a motor (9). The winding box (5) is fixedly installed on the front of the metal bracket (1). The winding rod (6) is movably installed inside the winding box (5). The transmission mechanism is located inside the winding box (5) and is connected to the winding rod (6) in a transmission connection. The motor (9) is connected to the transmission mechanism and is fixedly installed on the surface of the inner wall of the winding box (5). The transparent protective door (10) is movably connected to the surface of the winding rod (6) and can be raised and lowered along the opening direction of the winding box (5) to close or open the opening on the front of the metal bracket (1). The exhaust filtration system includes an exhaust fan (11), an inlet (12), an exhaust hood (15), a filter box (16), and a fan (17). The exhaust fan (11) is fixedly installed on the top of the top plate (3). The inlet (12) is opened on the top plate (3). The exhaust hood (15) is fixedly installed on the top of the inlet (12) and connected to the exhaust fan (11). One end of the filter box (16) is connected to the exhaust hood (15). The fan (17) is connected to the other end of the filter box (16). The exhaust filtration system is used to discharge and filter ammonia gas in the protective shed. The spray system includes a square tube (23), a nozzle (24) and a water inlet pipe (25). The square tube (23) is fixedly installed at the bottom of the metal crossbar (2). Multiple nozzles (24) are connected to the bottom of the square tube (23). The water inlet pipe (25) is connected to the surface of the square tube (23) and is connected to a water source. The ammonia detection system includes an ammonia detector (26) and an air inlet. The ammonia detector (26) is fixedly installed on the inner side of the metal bracket (1), and the air inlet is located on the wall behind the metal bracket (1). The controller controls the motor (9) to drive the transparent protective door (10) to descend and close according to the detection signal of the ammonia detector (26), controls the exhaust fan (11) and the blower (17) to start exhaust, and controls the water inlet pipe (25) to spray water, forming a multi-level linkage protection of detection-closure-exhaust-filtration-spraying.

2. The protective shed for preventing ammonia leakage for testing a dual-fuel ammonia main engine according to claim 1, characterized in that, The transmission mechanism includes a worm gear (7) and a worm (8). The worm gear (7) is fixedly installed on the surface of the winding rod (6). The worm (8) meshes with the surface of the worm gear (7). The output shaft of the motor (9) is fixedly connected to the bottom of the worm (8). The top of the worm (8) is movably connected to the surface of the inner wall of the winding box (5) through a bearing seat. When the ammonia detector (26) detects that the ammonia concentration exceeds the standard, the controller starts the motor (9) to drive the worm (8) to rotate, thereby rotating the worm gear (7) and the winding rod (6) and causing the transparent protective door (10) to descend and close the protective shed.

3. The protective shed for preventing ammonia leakage for testing a dual-fuel ammonia main engine according to claim 1, characterized in that, The inner wall of the opening (12) is movably connected to a plastic plate (13) by a pivot pin. A baffle (14) is fixedly installed on the top of the plastic plate (13). The baffle (14) is located on the side of the plastic plate (13) away from the pivot pin connection end. The plastic plate (13) remains horizontally closed to the opening (12) under the action of gravity. It flips upward and opens under the action of the exhaust fan (11).

4. The protective shed for preventing ammonia leakage for testing a dual-fuel ammonia main engine according to claim 1, characterized in that, The filter box (16) is provided with a polyester fiber mesh (18), granular activated carbon (19), 4A molecular sieve (20) and high-efficiency meltblown cloth (21) in sequence from the input end to the output end. The top of the filter box (16) is movably connected to a sealing plate (22) by a shaft pin. The polyester fiber mesh (18) is used to filter large particulate impurities, the granular activated carbon (19) is used to adsorb ammonia molecules, the 4A molecular sieve (20) is used to selectively adsorb small molecule gases, and the high-efficiency meltblown cloth (21) is used to finely filter residual particles.

5. The protective shed for preventing ammonia leakage for testing a dual-fuel ammonia main engine according to claim 1, characterized in that, Multiple metal crossbars (2) are fixedly installed in parallel between the tops of two metal brackets (1). The top plate (3) is laid on top of the multiple metal crossbars (2). The wall panel (4) is fixedly installed on both sides and the back of the metal bracket (1). The air inlet is located at the lower part of the back wall panel (4). The air inlet and the exhaust fan (11) form an airflow channel from bottom to top, and form an intersecting flow field with the spraying direction of the spraying system.

6. The protective shed for preventing ammonia leakage for testing a dual-fuel ammonia main engine according to claim 1, characterized in that, Multiple square tubes (23) are fixedly installed in parallel at the bottom of the metal crossbar (2). The bottom of each square tube (23) is connected to multiple nozzles (24). A solenoid valve is provided on the water inlet pipe (25). The controller controls the solenoid valve to open according to the detection signal of the ammonia detector (26), so that water passes through the square tube (23) and the nozzles (24) to form a water mist curtain. The spraying system is linked with the exhaust filtration system. After the water mist adsorbs ammonia, it is discharged through the exhaust filtration system.

7. The protective shed for preventing ammonia leakage during testing of a dual-fuel ammonia main unit according to claim 1, characterized in that, The ammonia detector (26) is located in the middle of the inner side of the metal bracket (1) and is used to monitor the ammonia concentration in the protective shed in real time. When the ammonia concentration exceeds the first preset threshold, the controller starts the transparent protective door (10) to descend and the exhaust filtration system to work. When the ammonia concentration exceeds the second preset threshold, the controller starts the spray system. When the ammonia concentration exceeds the third preset threshold, the controller starts the audible and visual alarm device. The first preset threshold is less than the second preset threshold, and the second preset threshold is less than the third preset threshold.

8. The protective shed for preventing ammonia leakage for testing a dual-fuel ammonia main engine according to claim 7, characterized in that, It also includes communication devices; When the ammonia detector (26) stops emitting alarm signals, the controller records the location, time, peak concentration and handling measures of the current leak event, and generates a maintenance report which is sent to the monitoring center through the communication device.

9. A control method for a protective shed to prevent ammonia leakage during the detection of a dual-fuel ammonia main engine, characterized in that, The protective shed applied to any one of claims 1-8 comprises: The signal from the ammonia detector (26) is collected in real time to monitor the ammonia concentration inside the protective shed; If the ammonia detector (26) detects that the ammonia concentration exceeds the first preset threshold, the motor (9) is started to drive the transparent protective door (10) to descend and close the protective shed, and the exhaust fan (11) and the blower (17) are started at the same time to filter the exhaust. If the ammonia concentration exceeds the second preset threshold, the solenoid valve of the water inlet pipe (25) will be opened for spraying. If the ammonia concentration drops to a safe range after a preset time, the spraying and exhaust will stop, and the transparent protective door (10) will be raised. If the ammonia concentration continues to exceed the third preset threshold within a preset time, an audible and visual alarm will be activated and the exhaust filtration will continue until manual intervention is required.

10. A dual-fuel ammonia engine detection system, characterized in that, Includes the protective shed for preventing ammonia leakage for testing a dual-fuel ammonia main engine as described in any one of claims 1-8.

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