Water mist protection method and system meeting fire protection and stability requirements

Abstract

The application relates to a water mist protection method and system meeting fireproof and stability requirements, comprising the following steps: installing a pressure opening valve on a corresponding water mist partition pipe in each water mist protection area; setting an opening pressure value of the pressure opening valve according to a broken-hull stability calculation result of a ship, wherein the opening pressure value is greater than the maximum hydrostatic pressure generated by the water mist partition pipe due to water filling of a corresponding cabin, and is less than the minimum water supply pressure of the fire water mist system when the pressure opening valve normally works; when the pressure inside the water mist partition pipe is less than or equal to the opening pressure value, the pressure opening valve keeps a closed state to cut off the communication between the water mist partition pipe and the water mist protection area; when the pressure inside the water mist partition pipe is greater than the opening pressure value, the pressure opening valve is automatically opened to make the fire water pass through and reach open water mist nozzles in the water mist protection area to spray water for fire extinguishing, which can meet the fireproof requirement, guarantee the broken-hull stability, and is safe, reliable and low in cost.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger technology, and more specifically, to a water mist protection method and system that meets fire prevention and stability requirements. Background Technology

[0002] Water mist fire suppression systems are widely used in cabin fire protection on various types of ships due to their advantages such as high fire extinguishing efficiency, low water consumption, and minimal impact on personnel and equipment. A typical shipboard full-coverage water mist protection system consists of a water mist pump unit that draws water from the freshwater tank and pumps it to the main water mist pipe. At each protected cabin above the waterline, the main water mist pipe is connected to a corresponding water mist zone pipe via water mist zone valves. Each water mist zone pipe extends into its corresponding protected area and contains several open water mist nozzles. When a fire occurs in a protected area, the fire detectors in that area send a signal to the control unit of the water mist protection system. The control unit then opens the corresponding water mist zone valve, allowing fire-fighting water to be delivered to the area via the water mist zone pipes and simultaneously sprayed through all the open water mist nozzles, thus controlling and extinguishing the fire.

[0003] However, the aforementioned conventional full-coverage water mist protection system presents significant safety hazards in practical applications. During navigation or operation, ships may experience hull breaches due to collisions, groundings, or other reasons. When a non-protected compartment (or passageway compartment) traversed by the water mist duct is damaged and flooded, seawater will enter the compartment according to damage stability calculations. Since the water mist duct is laid within this compartment, and the pipeline may have breaks or openings at the point of damage, seawater from outside will flow back into the pipeline system along the damaged duct. Under gravity, this seawater will flow along the pipeline and eventually exit through open water mist nozzles in other protected areas that have not experienced a fire. This process leads to unexpected flooding in undamaged protected areas, damaging equipment within those areas, increasing the ship's displacement, and generating heel or trim moments, thus severely impacting the ship's stability and even endangering its overall safety.

[0004] To avoid the stability deterioration caused by pipeline damage, a common technical approach employed by those skilled in the art is to install remote-controlled valves on the water mist ducts, near the inlet of the protected area. In the event of a breach, the crew or the automatic control system can remotely close this valve, thereby cutting off the channel for seawater to flow into the protected area. However, this solution introduces new problems: First, the remote-controlled valves and their associated control units, sensors, and cables are expensive, significantly increasing the ship's construction costs; second, this solution is highly dependent on correct operation by personnel or reliable operation of the control system. In emergencies, there is a risk that the valve may fail to close in time due to human delays, errors, or electrical / mechanical malfunctions of the valve itself, an uncertainty that is unacceptable for ship safety. Summary of the Invention

[0005] This application provides a water mist protection method and system that meets fire protection and stability requirements. It is a water mist protection design scheme that overcomes the above-mentioned defects of the prior art, meets fire protection requirements, ensures stability in case of damage, is safe and reliable, and is low in cost.

[0006] This application provides a water mist protection method that meets fire prevention and stability requirements, comprising the following steps: installing a pressure-opening valve on the corresponding water mist partition pipe in each water mist protection area; setting the opening pressure value of the pressure-opening valve according to the ship's damaged stability calculation results, wherein the opening pressure value is greater than the maximum static water pressure generated by the water mist partition pipe due to water ingress into the corresponding compartment due to damage, and less than the minimum water supply pressure of the fire-fighting water mist system when it is working normally at the pressure-opening valve; when the pressure inside the water mist partition pipe is less than or equal to the opening pressure value, the pressure-opening valve remains closed to cut off the connection between the water mist partition pipe and the water mist protection area; when the pressure inside the water mist partition pipe is greater than the opening pressure value, the pressure-opening valve automatically opens to allow fire-fighting water to pass through and reach the open water mist nozzles in the water mist protection area for fire extinguishing.

[0007] In some optional embodiments, the opening pressure value is set according to the following formula:

[0008] Wherein, P is the opening pressure value, H is the maximum waterline height of the vessel, h is the height of the pressure opening valve installation position from the vessel baseline, and Δh is the preset safety margin value.

[0009] In some optional embodiments, the safety margin value Δh is a preset pressure reserve value, used to ensure that the pressure opening valve can still remain sealed and closed under the hydrostatic pressure at the maximum breach waterline height H, so as to overcome the pressure uncertainty caused by fluid friction, local resistance and liquid level fluctuations in the pipe.

[0010] In some optional embodiments, the rated output pressure of the water mist pump assembly is greater than the sum of the opening pressure value, the pressure loss of the pipeline between the water mist partition valve and the pressure opening valve, the pressure loss of the pipeline between the pressure opening valve and the water mist nozzle under the most unfavorable operating conditions, and the minimum working pressure of the open water mist nozzle.

[0011] In some optional embodiments, the minimum water supply pressure of the fire-fighting water mist system when it is operating normally at the pressure opening valve is at least greater than the sum of the opening pressure value, the minimum operating pressure of the open water mist nozzle, and the pressure loss of the pipeline between the pressure opening valve and the open water mist nozzle.

[0012] In some optional embodiments, the pressure-opening valve is a normally closed, spring-loaded valve with adjustable opening pressure or a pilot-operated valve, and has the function of automatically resetting when the pressure in the open water mist partition pipe drops below the opening pressure value.

[0013] On the other hand, this application also provides a water mist protection system that meets fire resistance and stability requirements, used to perform the water mist protection method mentioned above that meets fire resistance and stability requirements, comprising: a water mist pump group, with its input end connected to a freshwater tank; a water mist main pipe, connected to the output end of the water mist pump group; multiple water mist partition valves, respectively disposed on the water mist main pipe; multiple water mist partition pipes, one end of each water mist partition pipe connected to the water mist main pipe through a water mist partition valve, and the other end of each water mist partition pipe extending to a corresponding water mist protection area; and open water mist nozzles disposed in each of the water mist protection areas and connected to... The corresponding water mist partition pipe; a pressure opening valve is installed on each of the water mist partition pipes and located between the water mist partition valve and the open water mist nozzle. The opening pressure value of the pressure opening valve is set according to the ship's damaged stability calculation results. When the pressure inside the water mist partition pipe is less than or equal to the opening pressure value, the pressure opening valve remains closed to cut off the connection between the water mist partition pipe and the water mist protection area. When the pressure inside the water mist partition pipe is greater than the opening pressure value, the pressure opening valve automatically opens to allow fire water to pass through and reach the open water mist nozzles in the water mist protection area for fire extinguishing.

[0014] In some optional embodiments, the opening pressure value is set according to the following formula:

[0015] Wherein, P is the opening pressure value, H is the maximum waterline height of the vessel, h is the height of the pressure opening valve installation position from the vessel baseline, and Δh is the preset safety margin value.

[0016] In some optional embodiments, the pressure-opening valve is a normally closed, spring-loaded valve with adjustable opening pressure or a pilot-operated valve, and has the function of automatically resetting when the pressure in the open water mist partition pipe drops below the opening pressure value.

[0017] In some alternative embodiments, the pressure-opening valve is located near the inlet of the water mist protection zone.

[0018] Compared with the prior art, the present invention has the following technical advantages: This application provides a water mist protection method that meets fire prevention and stability requirements, comprising the following steps: installing a pressure-opening valve on the corresponding water mist zone pipe within each water mist protection area; by setting the pressure-opening valve, the backflow channel can be automatically cut off under breach conditions, effectively preventing unexpected water ingress into the undamaged protection area, fundamentally eliminating the threat to ship stability caused by water mist system pipeline damage; setting the opening pressure value of the pressure-opening valve based on the ship's breach stability calculation results, wherein the opening pressure value is greater than the maximum static water pressure generated by water ingress into the corresponding compartment due to breach in the water mist zone pipe, and less than the minimum water supply pressure of the fire-fighting water mist system when it is working normally at the pressure-opening valve; when the pressure inside the water mist zone pipe is less than or equal to the opening pressure value, the pressure is opened. The valve remains closed to cut off the connection between the water mist zoning pipe and the water mist protection area, significantly improving the ship's breakage stability, avoiding the risk of capsizing due to asymmetrical water ingress, and ensuring the safety of life and property. When the pressure inside the water mist zoning pipe exceeds the opening pressure value, the pressure opening valve automatically opens to allow fire water to pass through and reach the open water mist nozzles in the water mist protection area for fire extinguishing, ensuring the absolute effectiveness of the fire prevention function. Under fire conditions, the system function is completely consistent with the conventional system, the nozzles can spray water normally for fire extinguishing, and no fire protection performance is sacrificed due to the addition of stability protection measures. The valve can be quickly and fully opened by the high-pressure fire water, ensuring that the fire water can reach all nozzles with sufficient pressure and flow, without affecting the normal fire extinguishing function of the water mist fire extinguishing system. Attached Figure Description

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 A schematic diagram of a water mist protection system that meets fire resistance and stability requirements according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a water mist protection system that meets fire resistance and stability requirements according to an embodiment of the present invention after the chamber is breached. Figure 3 This is a schematic flowchart illustrating a water mist protection method that meets fire resistance and stability requirements according to an embodiment of the present invention. Detailed Implementation

[0020] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0021] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0022] Water mist fire suppression systems are widely used in cabin fire protection on various types of ships due to their advantages such as high fire extinguishing efficiency, low water consumption, and minimal impact on personnel and equipment. The basic structure and working principle of a conventional full-coverage water mist protection system for ships are shown in the attached figure. Figure 1 As shown: The water mist pump unit draws water from the freshwater tank and pumps it to the main water mist pipe. The main water mist pipe connects to the corresponding water mist zone pipes at each protected compartment above the waterline via water mist zone valves. Each water mist zone pipe extends into its corresponding protected area, where several open water mist nozzles are installed. When a fire occurs in a protected area, the fire detector in that area sends a signal to the control unit of the water mist protection system. The control unit then opens the corresponding water mist zone valve, and fire-fighting water is delivered to that area through the water mist zone pipes and simultaneously sprayed through all the open water mist nozzles to control and extinguish the fire.

[0023] However, the aforementioned conventional full-coverage water mist protection system has significant safety hazards in practical applications. (See attached image) Figure 2 As shown, during navigation or operation, ships may experience hull breaches due to collisions, groundings, or other reasons. When a non-protected compartment (or passageway compartment) traversed by the water mist duct is damaged and flooded, seawater will enter the compartment according to damage stability calculations. Since the water mist duct is laid within this compartment, and the pipeline may have broken or opened at the point of damage, seawater from outside will flow back into the pipeline system along the damaged duct. Under the influence of gravity, this seawater will flow along the pipeline and eventually exit through the open water mist nozzles in other protected areas that have not experienced a fire. This process will cause unexpected flooding in undamaged protected areas, damaging equipment in those areas, increasing the ship's displacement, and generating heel or trim moments, thus severely impacting the ship's stability and even endangering its overall safety.

[0024] To avoid the stability deterioration caused by pipeline damage, a common technical approach employed by those skilled in the art is to install remote-controlled valves on the water mist ducts, near the inlet of the protected area. In the event of a breach, the crew or the automatic control system can remotely close this valve, thereby cutting off the channel for seawater to flow into the protected area. However, this solution introduces new problems: First, the remote-controlled valves and their associated control units, sensors, and cables are expensive, significantly increasing the ship's construction costs; second, this solution is highly dependent on correct operation by personnel or reliable operation of the control system. In emergencies, there is a risk that the valve may fail to close in time due to human delays, errors, or electrical / mechanical malfunctions of the valve itself, an uncertainty that is unacceptable for ship safety.

[0025] Based on the above, there is an urgent need for a water mist protection method that can meet fire protection and stability requirements in various installation scenarios, overcome the shortcomings of existing technologies, and provide a water mist protection design that satisfies both fire protection requirements and breach stability, while being safe, reliable, and cost-effective. The following refers to the accompanying drawings in the specification. Figures 1-3 A detailed explanation is provided of water mist protection methods that meet fire resistance and stability requirements.

[0026] This application provides a water mist protection method that meets fire prevention and stability requirements, comprising the following steps: installing a pressure-opening valve on the corresponding water mist partition pipe in each water mist protection area; setting the opening pressure value of the pressure-opening valve according to the ship's damaged stability calculation results, wherein the opening pressure value is greater than the maximum static water pressure generated by the water mist partition pipe due to water ingress into the corresponding compartment due to damage, and less than the minimum water supply pressure of the fire-fighting water mist system when it is working normally at the pressure-opening valve; when the pressure inside the water mist partition pipe is less than or equal to the opening pressure value, the pressure-opening valve remains closed to cut off the connection between the water mist partition pipe and the water mist protection area; when the pressure inside the water mist partition pipe is greater than the opening pressure value, the pressure-opening valve automatically opens to allow fire-fighting water to pass through and reach the open water mist nozzles in the water mist protection area for fire extinguishing.

[0027] Specifically, in conventional systems, when a hull is breached, seawater will backflow and flow out from nozzles in intact areas, seriously threatening the stability of the ship. This application uses a pressure threshold as a criterion to achieve automatic shut-off in the low-pressure state under backflow conditions. When the pressure in the partition pipe is less than or equal to the opening pressure value, the pressure opening valve remains closed, completely blocking the path of backflowing seawater into the protected area. The pressure in the partition pipe comes from the gravity of the backflowing seawater, which significantly improves the ship's stability under damage, avoids the risk of ship capsizing due to asymmetrical water ingress, and ensures the safety of life and property.

[0028] To avoid the aforementioned stability deterioration caused by pipeline damage, those skilled in the art typically install remote-controlled valves on the water mist zone pipes, near the inlet of the protected area. However, these remote-controlled valves, along with their associated control units, sensors, and cables, are costly, significantly increasing shipbuilding costs. They also rely on manual / electrical operation and are susceptible to malfunctions and delays. This application employs a purely mechanical pressure-opening valve. The opening and closing of this valve is entirely driven by the water pressure within the pipe, requiring no electricity, control signals, or manual operation. This reduces system costs, eliminates the risks of human error and electrical faults, and improves system reliability. In case of fire, the valve opens immediately upon the arrival of high-pressure water; in case of breaching, it closes immediately upon the arrival of low-pressure water, with no time delay.

[0029] Similarly, by utilizing pressure thresholds, automatic high-pressure fire suppression is achieved. When the pressure in the zone pipe exceeds the opening pressure value, the pressure in this zone pipe comes from the high-pressure water from the fire pump, and the pressure opening valve automatically opens to ensure unobstructed fire water flow. This ensures that while achieving the above functions, normal fire suppression functions are not affected, ensuring the absolute effectiveness of the fire prevention function. Under fire conditions, the system functions completely identically to conventional systems, and the sprinklers can spray water normally for fire suppression without sacrificing any fire protection performance due to the addition of stability protection measures.

[0030] This application utilizes a pressure-opening valve to automatically cut off backflow channels in the event of a breach, effectively preventing unexpected water ingress into undamaged protected areas and fundamentally eliminating the threat to ship stability caused by damage to the water mist system pipeline. Employing a purely mechanical pressure-opening valve, its operation requires no external energy, control signals, or personnel; it relies entirely on the water pressure within the pipe for automatic completion. This avoids the risks of delays or errors caused by human operation and eliminates potential electrical faults that may arise from remote-controlled valves and their control systems, significantly improving the reliability of the entire system. In fire conditions, the pressure-opening valve opens rapidly and fully due to the high-pressure firefighting water, ensuring that firefighting water reaches all nozzles with sufficient pressure and flow, without affecting the normal firefighting function of the water mist extinguishing system. Using only a standard pressure-opening valve, without the need for complex control systems and cables, significantly reduces the ship's construction and maintenance costs, demonstrating high economic efficiency and practicality.

[0031] In some optional embodiments, the opening pressure value is set according to the following formula:

[0032] Where P is the opening pressure value, H is the maximum waterline height of the ship, h is the height of the pressure opening valve installation position from the ship's baseline, and Δh is the preset safety margin value.

[0033] Specifically, the maximum breach waterline height H is taken from the ship's breach stability calculation report, corresponding to the final equilibrium water level height under the most unfavorable breach condition in the area served and protected by the water mist zone control pipe. The safety margin value Δh is a static pressure margin, measured in meters of water column, and is an equivalent representation of pressure. The purpose of the safety margin value Δh is to provide a safety boundary for the system, ensuring that under the influence of various adverse factors such as calculation errors, liquid level fluctuations, and changes in seawater density, the pressure of seawater flowing back into the breach will absolutely not be able to open the pressure-opening valve. The safety margin value Δh is a preset pressure reserve value, used to ensure that the pressure-opening valve remains sealed and closed under the hydrostatic pressure at the maximum breach waterline height H, overcoming pressure uncertainties caused by fluid friction within the pipe, local resistance, and liquid level fluctuations.

[0034] The nozzle spray height is a dynamic fire extinguishing performance parameter, referring to the physical height or coverage area that the water mist can reach after the water mist head atomizes and sprays the fire-fighting water. The minimum operating pressure of the nozzle must be greater than the sum of the rated output pressure of the water mist pump unit, pipeline losses, and the minimum operating pressure of the open water mist nozzle. This ensures that, under fire extinguishing conditions, the nozzle can generate effective water mist and achieve its specified spray height and protection range.

[0035] Optionally, for example, if the maximum breach waterline height of the ship is 12 meters from the ship's baseline, and the pressure-opening valve is installed 3 meters above the ship's baseline, then P = (12 - 3 + 1) meters of water column = 1 bar. That is, when the liquid pressure in the water mist partition pipe is less than 1 bar, the pressure-opening valve remains closed; when the liquid pressure in the water mist partition pipe is greater than 1 bar, the valve will automatically open.

[0036] The design pressure of the water mist pump set must be selected to ensure that the pressure of the water mist fire-fighting water reaching the nozzle at the end of the water mist zone pipe is greater than the set opening pressure value P of the pressure opening valve.

[0037] When a fire occurs in a water mist protection zone, the fire detectors in the room will send a fire signal back to the water mist protection system. The water mist protection system will then open the corresponding water mist zone valve, and the water mist protection fire water will be quickly pumped to the water mist protection zone where the fire occurred. Since the water pressure of the water mist protection fire water reaching the water mist protection zone is greater than the set opening pressure value P of the pressure opening valve, it can reach the position of the open water mist nozzle through the pressure opening valve and start spraying water to control and extinguish the fire in the area.

[0038] When a breach occurs in a room along the path of the water mist zone pipe, the corresponding pipes in that room must also be considered to be damaged. The seawater that has entered the damaged room will enter the water mist protection zone pipe that passes through the damaged room. When the water in the water mist zone pipe reaches the pressure opening valve, since the pressure inside the pipe comes from the gravity of the seawater entering the damaged room, its pressure value cannot exceed the set pressure P of the pressure opening valve. Therefore, the water in the water mist zone pipe cannot pass through the pressure opening valve and cannot flow from the open water mist nozzle to the corresponding water mist protection area, thus preventing water from entering the undamaged water mist protection area.

[0039] In some optional embodiments, the safety margin value Δh is a preset pressure reserve value used to ensure that the pressure opening valve can remain sealed and closed under the hydrostatic pressure at the maximum breach waterline height H, so as to overcome the pressure uncertainty caused by fluid friction, local resistance and liquid level fluctuations in the pipe.

[0040] Specifically, by setting a clear and sufficient pressure threshold, it is ensured that even under the most unfavorable breach conditions, where seawater has filled the compartment to its maximum theoretical height H, the pressure generated by the backflowing seawater will always be less than the valve opening pressure. This eliminates the possibility of seawater accidentally flooding into intact compartments. The safety margin value Δh provides a safety buffer that effectively absorbs these unknown and disturbing factors, ensuring that the valve will not be accidentally opened due to these minor pressure fluctuations.

[0041] In some alternative embodiments, the rated output pressure of the water mist pump unit is greater than the sum of the opening pressure, the pressure loss in the pipeline between the water mist partition valve and the pressure opening valve, the pressure loss in the pipeline between the pressure opening valve and the water mist nozzle under the most unfavorable operating conditions, and the minimum operating pressure of the open water mist nozzle.

[0042] Specifically, by setting the rated output pressure of the water mist pump set to be greater than the sum of the opening pressure value, pipeline losses, and the minimum working pressure of the nozzle, it is ensured that under all operating conditions, especially at the most unfavorable nozzle where pipeline losses are greatest, the fire water pressure can still reliably open the pressure opening valve and meet the atomization pressure requirements of the nozzle. This ensures the effectiveness and reliability of the fire extinguishing system, provides sufficient power reserves for the system, and enables the pressure opening valve to open quickly and completely under fire water pressure, avoiding the valve being in a half-open state due to insufficient pressure and ensuring the fire extinguishing water flow.

[0043] In some alternative embodiments, the minimum water supply pressure of the fire-fighting water mist system when it is operating normally at the pressure-opening valve is at least greater than the sum of the opening pressure value, the minimum operating pressure of the open water mist nozzle, and the pressure loss of the pipeline between the pressure-opening valve and the open water mist nozzle.

[0044] Specifically, the minimum water supply pressure at the pressure-limiting valve is at least greater than the sum of the opening pressure, the minimum working pressure of the nozzle, and the pressure loss of the pipeline downstream of the valve. This ensures that after the fire water passes through the pressure-opening valve, the remaining pressure is still sufficient to drive the open water mist nozzle to achieve the atomization state required by the design, thus ensuring the independent and reliable fire extinguishing capability of the pipeline downstream of the valve and the nozzle.

[0045] In some alternative embodiments, the pressure-opening valve is a normally closed, spring-loaded valve with adjustable opening pressure or a pilot-operated valve, and has the function of automatically resetting when the pressure in the open water mist zone pipe drops below the opening pressure value.

[0046] Specifically, the pressure-opening valve enables the system to automatically reset after fire extinguishing or troubleshooting, restoring fire prevention and stability protection functions without manual intervention. This ensures the continuous availability of the system and the long-term safety of the ship, completely eliminating dependence on electricity, control systems, and human operation. It can still operate reliably in extreme and harsh environments such as fires and hull breaches, greatly improving the inherent safety and robustness of the system in emergency situations.

[0047] On the other hand, this application also provides a water mist protection system that meets fire resistance and stability requirements, used to perform the water mist protection method mentioned above that meets fire resistance and stability requirements, including: a water mist pump group with its input end connected to a freshwater tank; a water mist main pipe connected to the output end of the water mist pump group; multiple water mist partition valves, each disposed on the water mist main pipe; multiple water mist partition pipes, one end of each water mist partition pipe connected to the water mist main pipe through a water mist partition valve, and the other end of each water mist partition pipe extending to the corresponding water mist protection area; and open water mist nozzles disposed in each water mist protection area. Within the area, it is connected to the corresponding water mist zone pipe; a pressure opening valve is installed on each water mist zone pipe and located between the water mist zone valve and the open water mist nozzle. The opening pressure value of the pressure opening valve is set according to the ship's damaged stability calculation results; when the pressure inside the water mist zone pipe is less than or equal to the opening pressure value, the pressure opening valve remains closed to cut off the connection between the water mist zone pipe and the water mist protection area; when the pressure inside the water mist zone pipe is greater than the opening pressure value, the pressure opening valve automatically opens to allow fire water to pass through and reach the open water mist nozzles in the water mist protection area for fire extinguishing.

[0048] Specifically, in conventional systems, when a hull is breached, seawater will backflow and flow out from nozzles in intact areas, seriously threatening the stability of the ship. This application uses a pressure threshold as a criterion to achieve automatic shut-off in the low-pressure state under backflow conditions. When the pressure in the partition pipe is less than or equal to the opening pressure value, the pressure opening valve remains closed, completely blocking the path of backflowing seawater into the protected area. The pressure in the partition pipe comes from the gravity of the backflowing seawater, which significantly improves the ship's stability under damage, avoids the risk of ship capsizing due to asymmetrical water ingress, and ensures the safety of life and property.

[0049] To avoid the aforementioned stability deterioration caused by pipeline damage, those skilled in the art typically install remote-controlled valves on the water mist zone pipes, near the inlet of the protected area. However, these remote-controlled valves, along with their associated control units, sensors, and cables, are costly, significantly increasing shipbuilding costs. They also rely on manual / electrical operation and are susceptible to malfunctions and delays. This application employs a purely mechanical pressure-opening valve. The opening and closing of this valve is entirely driven by the water pressure within the pipe, requiring no electricity, control signals, or manual operation. This reduces system costs, eliminates the risks of human error and electrical faults, and improves system reliability. In case of fire, the valve opens immediately upon the arrival of high-pressure water; in case of breaching, it closes immediately upon the arrival of low-pressure water, with no time delay.

[0050] Similarly, by utilizing pressure thresholds, automatic high-pressure fire suppression is achieved. When the pressure in the zone pipe exceeds the opening pressure value, the pressure in this zone pipe comes from the high-pressure water from the fire pump, and the pressure opening valve automatically opens to ensure unobstructed fire water flow. This ensures that while achieving the above functions, normal fire suppression functions are not affected, ensuring the absolute effectiveness of the fire prevention function. Under fire conditions, the system functions completely identically to conventional systems, and the sprinklers can spray water normally for fire suppression without sacrificing any fire protection performance due to the addition of stability protection measures.

[0051] In some optional embodiments, the opening pressure value is set according to the following formula:

[0052] Wherein, P is the opening pressure value, H is the maximum waterline height of the vessel, h is the height of the pressure opening valve installation position from the vessel baseline, and Δh is the preset safety margin value.

[0053] Specifically, the maximum breach waterline height H is taken from the ship's breach stability calculation report, corresponding to the final equilibrium water level height under the most unfavorable breach condition in the area served and protected by the water mist zone control pipe. The safety margin value Δh is a static pressure margin, measured in meters of water column, and is an equivalent representation of pressure. The purpose of the safety margin value Δh is to provide a safety boundary for the system, ensuring that under the influence of various adverse factors such as calculation errors, liquid level fluctuations, and changes in seawater density, the pressure of seawater flowing back into the breach will absolutely not be able to open the pressure-opening valve. The safety margin value Δh is a preset pressure reserve value, used to ensure that the pressure-opening valve remains sealed and closed under the hydrostatic pressure at the maximum breach waterline height H, overcoming pressure uncertainties caused by fluid friction within the pipe, local resistance, and liquid level fluctuations.

[0054] The nozzle spray height is a dynamic fire extinguishing performance parameter, referring to the physical height or coverage area that the water mist can reach after the water mist head atomizes and sprays the fire-fighting water. The minimum operating pressure of the nozzle must be greater than the sum of the rated output pressure of the water mist pump unit, pipeline losses, and the minimum operating pressure of the open water mist nozzle. This ensures that, under fire extinguishing conditions, the nozzle can generate effective water mist and achieve its specified spray height and protection range.

[0055] In some alternative embodiments, the pressure-opening valve is a normally closed, spring-loaded valve with adjustable opening pressure or a pilot-operated valve, and has the function of automatically resetting when the pressure in the open water mist zone pipe drops below the opening pressure value.

[0056] Specifically, the pressure-opening valve enables the system to automatically reset after fire extinguishing or troubleshooting, restoring fire prevention and stability protection functions without manual intervention. This ensures the continuous availability of the system and the long-term safety of the ship, completely eliminating dependence on electricity, control systems, and human operation. It can still operate reliably in extreme and harsh environments such as fires and hull breaches, greatly improving the inherent safety and robustness of the system in emergency situations.

[0057] In some alternative embodiments, the pressure-opening valve is located near the inlet of the water mist protection zone.

[0058] Specifically, by placing the pressure-opening valve near the inlet of the water mist protection area, the length of the pipeline that may allow water to enter downstream of the valve is minimized, reducing the impact of a breach accident on the protected area to the minimum. This significantly improves the ship's local damage stability and forms a clear protection boundary at the pressure-opening valve, completely isolating the path of seawater backflow into the protected area caused by upstream pipeline damage. This ensures the independence and reliability of the protection of each protected area and reduces the probability of downstream pipelines being exposed to external damage risks.

[0059] In this invention, the term "multiple" refers to at least two or more, unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0060] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A water mist protection method that meets fire resistance and stability requirements, characterized in that, Includes the following steps: A pressure-opening valve is installed on the corresponding water mist zone pipe in each water mist protection area; Based on the ship's damaged stability calculation results, the opening pressure value of the pressure opening valve is set, wherein the opening pressure value is greater than the maximum static water pressure generated by the water mist zone pipe due to the water ingress of the corresponding compartment due to damage, and less than the minimum water supply pressure of the fire water mist system when it is working normally at the pressure opening valve. When the pressure inside the water mist partition pipe is less than or equal to the opening pressure value, the pressure opening valve remains closed to cut off the connection between the water mist partition pipe and the water mist protection area. When the pressure inside the water mist zone pipe is greater than the opening pressure value, the pressure opening valve automatically opens, allowing fire water to pass through and reach the open water mist nozzles in the water mist protection area for fire extinguishing.

2. The water mist protection method that meets the requirements of fire resistance and stability according to claim 1, characterized in that, The opening pressure value is set according to the following formula: Wherein, P is the opening pressure value, H is the maximum waterline height of the vessel, h is the height of the pressure opening valve installation position from the vessel baseline, and Δh is the preset safety margin value.

3. The water mist protection method that meets the requirements of fire resistance and stability according to claim 2, characterized in that, The safety margin value Δh is a preset pressure reserve value used to ensure that the pressure opening valve can remain sealed and closed under the hydrostatic pressure at the maximum breach waterline height H, so as to overcome the pressure uncertainty caused by fluid friction, local resistance and liquid level fluctuations in the pipe.

4. The water mist protection method that meets the requirements of fire resistance and stability according to claim 1, characterized in that, The rated output pressure of the water mist pump set is greater than the opening pressure value, the pressure loss of the pipeline between the water mist partition valve and the pressure opening valve, the pressure loss of the pipeline between the pressure opening valve and the water mist nozzle under the most unfavorable working condition, and the minimum working pressure of the open water mist nozzle.

5. The water mist protection method that meets the requirements of fire resistance and stability according to claim 1, characterized in that, The minimum water supply pressure of the fire-fighting water mist system when it is working normally at the pressure opening valve is at least greater than the sum of the opening pressure value, the minimum working pressure of the open water mist nozzle, and the pressure loss of the pipeline between the pressure opening valve and the open water mist nozzle.

6. The water mist protection method that meets the requirements of fire resistance and stability according to claim 1, characterized in that, The pressure-opening valve is a normally closed, spring-loaded valve or pilot-operated valve with adjustable opening pressure, and has the function of automatically resetting when the pressure in the open water mist zone pipe drops below the opening pressure value.

7. A water mist protection system that meets fire resistance and stability requirements, characterized in that, A water mist protection method for performing any one of claims 1-6 that meets the requirements of fire resistance and stability includes: Water mist pump unit, with the input end connected to the freshwater tank; The main water mist pipe is connected to the output end of the water mist pump unit; Multiple water mist zone valves are respectively installed on the main water mist pipe; Multiple water mist partition pipes, one end of each water mist partition pipe is connected to the main water mist pipe through a water mist partition valve, and the other end of each water mist partition pipe extends to the corresponding water mist protection area; Open water mist nozzles are installed in each of the water mist protection areas and connected to the corresponding water mist zone pipes; A pressure-opening valve is installed on each of the water mist partition pipes and is located between the water mist partition valve and the open water mist nozzle. The opening pressure value of the pressure-opening valve is set according to the ship's damage stability calculation results. When the pressure inside the water mist partition pipe is less than or equal to the opening pressure value, the pressure opening valve remains closed to cut off the connection between the water mist partition pipe and the water mist protection area. When the pressure inside the water mist zone pipe is greater than the opening pressure value, the pressure opening valve automatically opens, allowing fire water to pass through and reach the open water mist nozzles in the water mist protection area for fire extinguishing.

8. The water mist protection system that meets the requirements of fire resistance and stability according to claim 7, characterized in that, The opening pressure value is set according to the following formula: Wherein, P is the opening pressure value, H is the maximum waterline height of the vessel, h is the height of the pressure opening valve installation position from the vessel baseline, and Δh is the preset safety margin value.

9. The water mist protection system that meets the requirements of fire resistance and stability according to claim 7, characterized in that, The pressure-opening valve is a normally closed, spring-loaded valve or pilot-operated valve with adjustable opening pressure, and has the function of automatically resetting when the pressure in the open water mist zone pipe drops below the opening pressure value.

10. The water mist protection system that meets the requirements of fire resistance and stability according to claim 9, characterized in that, The pressure-opening valve is located near the inlet of the water mist protection area.

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