Ship LNG (Liquefied Natural Gas) dual-fuel ventilation system and control method thereof

Abstract

The invention provides a ship LNG dual-fuel ventilation system and a control method thereof. The ship LNG dual-fuel ventilation system comprises an air brake room isolation unit, a mechanical air supply module, a natural exhaust channel, a dynamic pressure management system and a fault emergency unit. The air brake isolation unit is arranged in a transition area between an LNG fuel cabin and a cabin, and the physical isolation structure of the air brake isolation unit conforms to the IGF Code standard. The mechanical air supply module comprises a main fan and a standby fan which are arranged in parallel, and is provided with a main power supply and an emergency power supply of a double-circuit power supply interface connection system; the natural exhaust channel is provided with an explosion-proof gravity baffle and a fireproof air brake; the dynamic pressure management system comprises a pressure sensor, a flow switch and a controller, and the positive pressure value between air brakes is maintained to be larger than or equal to 50 Pa in real time. The fault emergency unit comprises a power supply monitoring module and a fan switching actuator. According to the technical scheme, through multi-stage control logic, two-way redundancy power supply and intelligent pressure management, the problems that a traditional LNG ship ventilation system is insufficient in dynamic pressure control, weak in redundancy design and lagged in emergency response can be solved.

Description

Technical Field

[0001] The present invention belongs to the field of ship LNG dual-fuel power systems, and in particular relates to a ship LNG dual-fuel ventilation system and a control method thereof. Background Art

[0002] With the gradual promulgation and implementation of oil bans both domestically and internationally, the market for new energy vessels is booming. LNG is the primary type of new energy vessel, but due to the flammability and explosiveness of LNG fuel, the extensive use of explosion-proof equipment increases the design and construction costs of vessels.

[0003] Traditional LNG ship ventilation systems suffer from insufficient dynamic pressure control, weak redundancy design, and delayed emergency response. Insufficient dynamic pressure control refers to the existing system's inability to adjust ventilation volume in real time based on gas leaks, resulting in excessive cabin pressure fluctuations and the potential for gas accumulation. Weak redundancy design refers to the single-circuit power supply and single-fan configuration, which can easily lead to system failure in the event of a fault, failing to meet the IMO Tier III safety redundancy requirements. Delayed emergency response refers to the traditional reliance on manual judgment for fault detection, resulting in time-consuming power switching and isolating hazardous areas, which fails to meet the safety requirements of LNG fuel tanks for rapid response.

[0004] Therefore, how to provide a ship LNG dual-fuel ventilation system and its control method to solve the above technical defects through multi-level control logic, dual redundant power supply and intelligent pressure management has become a technical problem that needs to be solved urgently. Summary of the Invention

[0005] An embodiment of the present invention provides a ship LNG dual-fuel ventilation system and a control method thereof. Through multi-level control logic, dual-circuit redundant power supply and intelligent pressure management, it can solve the problems of insufficient dynamic pressure control, weak redundant design and delayed emergency response in traditional LNG ship ventilation systems.

[0006] In one embodiment of the present invention, a ship LNG dual-fuel ventilation system is provided, comprising: an airlock isolation unit 100, a mechanical air supply module 200, a natural exhaust channel 300, a dynamic pressure management system 400 and a fault emergency unit 500.

[0007] The airlock isolation unit 100 is located in the transition area between the LNG fuel tank and the engine room, and its physical isolation structure complies with the requirements of the IGF Code.

[0008] The mechanical air supply module 200 includes a main fan 210 and a backup fan 220 arranged in parallel, and is equipped with a dual power supply interface 230 to connect the main power supply and emergency power supply of the system;

[0009] The natural exhaust passage 300 is provided with an explosion-proof gravity baffle 310 and a fire damper 320;

[0010] Dynamic pressure management system 400, including pressure sensor 410, flow switch 420 and controller 430, maintains positive pressure value of airlock room ≥50Pa in real time;

[0011] The fault emergency unit 500 includes a power supply monitoring module 510 and a fan switching actuator 520 .

[0012] Furthermore, the dual power supply interface 230 includes: a direct power supply line from the main distribution board and a power supply line for an emergency generator connected via a transfer switch, and an electrical interlocking device 231 is provided between the two power supply lines.

[0013] Furthermore, the dynamic pressure management system 400 is configured with three levels of control logic:

[0014] First-level response: triggering the frequency conversion speed regulation of the main fan 210 through the pressure sensor 410;

[0015] Second-level response: when the pressure value is lower than 45Pa, the standby fan 220 is started to run in parallel;

[0016] Level 3 response: When the pressure value is lower than 40Pa for 30 seconds, the hazardous area isolation signal is activated.

[0017] Furthermore, the fault emergency unit 500 is provided with a dual fault detection mechanism, including: a fan mechanical fault diagnosis module 511 and a power supply fault diagnosis module 512;

[0018] The fan mechanical fault diagnosis module 511 is based on current fluctuation detection, and the power supply fault diagnosis module 512 is based on voltage phase detection. The two modules trigger the switching actuator 520 through an OR logic relationship.

[0019] In another embodiment of the present invention, a method for controlling a ship LNG dual-fuel ventilation system is provided, based on any one of the above ship LNG dual-fuel ventilation systems, comprising:

[0020] S101: When the system starts, the main fan 210 is started first, and a reference pressure curve is established through the pressure sensor 410;

[0021] S102, comparing the deviation between the current pressure value and the set threshold value of 50±5Pa in real time;

[0022] S103, when the difference exceeds 10%, the standby fan 220 is started for parallel compensation operation;

[0023] S104: When an abnormality in the main power supply is detected, the system switches to the emergency power supply within 0.3s to 0.5s.

[0024] S105: When the pressure value is lower than 35Pa for 30 seconds, an area isolation command is sent to the ship's central control system.

[0025] Furthermore, in step S103, a nonlinear compensation algorithm is set to specifically satisfy the following functional relationship:

[0026] Q_ 补偿 =K1×ΔP+K2×(ΔP)^2

[0027] Among them, Q_ 补偿 To compensate for the air volume, ΔP is the pressure deviation, K1 = 0.8 ~ 1.2, K2 = 0.05 ~ 0.15.

[0028] Furthermore, the power switching operation in step S104 includes a pre-synchronization detection phase, specifically including:

[0029] Detect the voltage amplitude difference of the emergency power supply ≤±5%;

[0030] Detection frequency difference ≤±0.2Hz;

[0031] The phase angle difference is detected to be ≤±5 degrees, and seamless switching is performed when all conditions are met.

[0032] The beneficial effects brought about by the present invention are as follows:

[0033] As can be seen from the above scheme, an embodiment of the present invention provides a ship LNG dual-fuel ventilation system and control method thereof, comprising: an airlock isolation unit 100, a mechanical air supply module 200, a natural exhaust duct 300, a dynamic pressure management system 400, and a fault emergency unit 500. The airlock isolation unit 100 is arranged in the transition area between the LNG fuel tank and the engine room, and its physical isolation structure complies with the requirements of the IGF Code specification; the mechanical air supply module 200 includes a main fan 210 and a backup fan 220 arranged in parallel, and is equipped with a dual power supply interface 230 to connect the system's main power supply and emergency power supply; the natural exhaust duct 300 is equipped with an explosion-proof gravity baffle 310 and a fire damper 320; the dynamic pressure management system 400 includes a pressure sensor 410, a flow switch 420, and a controller 430 to maintain a positive pressure value of ≥50Pa between the airlocks in real time; and the fault emergency unit 500 includes a power monitoring module 510 and a fan switching actuator 520. The technical solution of the present invention, through multi-level control logic, dual redundant power supply and intelligent pressure management, can solve the problems of insufficient dynamic pressure control, weak redundant design and delayed emergency response in traditional LNG ship ventilation systems.

[0034] Figure Description

[0035] Figure 1This is a schematic structural diagram of a ship LNG dual-fuel ventilation system according to an embodiment of the present invention;

[0036] In the figure, 100 is the airlock isolation unit, 200 is the mechanical air supply module, 210 is the main fan, 220 is the backup fan, 300 is the natural exhaust channel, 310 is the explosion-proof gravity baffle, 320 is the fire damper, 400 is the dynamic pressure management system, 410 is the pressure sensor, 420 is the flow switch, 430 is the controller, 500 is the fault emergency unit, 510 is the power monitoring module, and 520 is the fan switching actuator. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0038] like Figure 1 As shown, Figure 1 This is a schematic structural diagram of a ship LNG dual-fuel ventilation system according to an embodiment of the present invention.

[0039] In the figure, a ship LNG dual-fuel ventilation system includes: an airlock isolation unit 100, a mechanical air supply module 200, a natural exhaust channel 300, a dynamic pressure management system 400 and a fault emergency unit 500.

[0040] The airlock isolation unit 100 is located in the transition area between the LNG fuel tank and the engine room, and its physical isolation structure complies with the requirements of the IGF Code.

[0041] The mechanical air supply module 200 includes a main fan 210 and a backup fan 220 arranged in parallel, and is equipped with a dual power supply interface 230 to connect the main power supply and emergency power supply of the system;

[0042] The natural exhaust passage 300 is provided with an explosion-proof gravity baffle 310 and a fire damper 320;

[0043] Dynamic pressure management system 400, including pressure sensor 410, flow switch 420 and controller 430, maintains positive pressure value of airlock room ≥50Pa in real time;

[0044] The fault emergency unit 500 includes a power supply monitoring module 510 and a fan switching actuator 520 .

[0045] The isolation unit 100 adopts a physical isolation structure that complies with the IGF Code specifications, effectively isolating the LNG fuel tank from the engine room and preventing the spread of gas to non-explosion-proof areas. In the mechanical air supply module 200, the main and standby fans are designed in parallel, combined with the dual power supply interface 230 to ensure that the air supply volume can still be maintained at more than 50% in the event of a single fault, meeting the IMO safety redundancy standard. In the natural exhaust duct 300, the explosion-proof gravity baffle 310 and the fire damper 320 automatically open in the event of a gas leak, achieving unpowered smoke exhaust and reducing the risk of explosion. The dynamic pressure management system 400 adjusts the pressure in real time through three-level control logic to maintain a positive pressure of ≥50Pa, preventing the backflow of external air from causing the gas concentration to exceed the standard. The fault emergency unit 500, with its dual fault detection mechanism, can complete power switching within 0.5 seconds to ensure continuous operation of the system.

[0046] In another embodiment of the present invention, the dual power supply interface 230 includes: a direct power supply line of the main distribution board and an emergency generator power supply line connected via a transfer switch, and an electrical interlocking device 231 is provided between the two power supply lines.

[0047] The main and emergency power supplies seamlessly switch via an electrical interlock 231, preventing power conflicts. The emergency generator power supply circuit can continue to provide power to the ventilation system in the event of a main power grid failure, meeting the high reliability requirements of LNG vessels for critical systems.

[0048] In another embodiment of the present invention, the dynamic pressure management system 400 is configured with a three-level control logic:

[0049] First-level response: triggering the frequency conversion speed regulation of the main fan 210 through the pressure sensor 410;

[0050] Second-level response: when the pressure value is lower than 45Pa, the standby fan 220 is started to run in parallel;

[0051] Level 3 response: When the pressure value is lower than 40Pa for 30 seconds, the hazardous area isolation signal is activated.

[0052] In this embodiment of the present invention, variable frequency speed regulation dynamically adjusts the main fan speed based on pressure deviation, achieving energy savings of up to 20%. When the backup fan is activated, it activates when the pressure drops below 45 Pa, ensuring that the pressure returns to a safe threshold. During zone isolation, sustained low pressure triggers an isolation command to prevent gas from spreading to adjacent compartments, complying with the IGF Code's hazardous area classification requirements.

[0053] In another embodiment of the present invention, the fault emergency unit 500 is provided with a dual fault detection mechanism, including: a fan mechanical fault diagnosis module 511 and a power supply fault diagnosis module 512;

[0054] The fan mechanical fault diagnosis module 511 is based on current fluctuation detection, and the power supply fault diagnosis module 512 is based on voltage phase detection. The two modules trigger the switching actuator 520 through an OR logic relationship.

[0055] In another embodiment of the present invention, a method for controlling a ship LNG dual-fuel ventilation system is provided, based on any one of the above ship LNG dual-fuel ventilation systems, comprising:

[0056] S101: When the system starts, the main fan 210 is started first, and a reference pressure curve is established through the pressure sensor 410;

[0057] S102, comparing the deviation between the current pressure value and the set threshold value of 50±5Pa in real time;

[0058] S103, when the difference exceeds 10%, the standby fan 220 is started for parallel compensation operation;

[0059] S104: When an abnormality in the main power supply is detected, the system switches to the emergency power supply within 0.3s to 0.5s.

[0060] S105: When the pressure value is lower than 35Pa for 30 seconds, an area isolation command is sent to the ship's central control system.

[0061] In the embodiment of the present invention, a nonlinear compensation algorithm is set in step S103, specifically satisfying the following functional relationship:

[0062] Q_ 补偿 =K1×ΔP+K2×(ΔP)^2

[0063] Among them, Q_ 补偿 To compensate for the air volume, ΔP is the pressure deviation, K1 = 0.8 ~ 1.2, K2 = 0.05 ~ 0.15.

[0064] Among them, through the quadratic function relationship (Q_ 补偿 =K1×ΔP+K2×(ΔP)^2) accurately matches and compensates for air volume, resolving overshoot issues caused by linear control. Triple calibration of voltage, frequency, and phase angle ensures seamless power switching, minimizing the risk of turbine downtime. Abnormal pressure within 30 seconds triggers central system linkage, meeting the rapid containment requirements of LNG vessels for gas leaks.

[0065] In another embodiment of the present invention, the power switching operation in step S104 includes a pre-synchronization detection phase, specifically including:

[0066] Detect the voltage amplitude difference of the emergency power supply ≤±5%;

[0067] Detection frequency difference ≤±0.2Hz;

[0068] The phase angle difference is detected to be ≤±5 degrees, and seamless switching is performed when all conditions are met.

[0069] In one embodiment of the present invention, a ship LNG dual-fuel ventilation system is provided, wherein the airlock isolation unit adopts A60 fireproof separation, is equipped with airtight doors and leakage sensors, and complies with the requirements of Article 7.2 of the IGF Code. Mechanical air supply module: The main fan 210 uses an explosion-proof centrifugal fan (air volume ≥ 5000m 3 / h). Standby fan 220 is equipped with an independent air duct to avoid cross-wind interference. Dynamic pressure control: Pressure sensor 410 adopts a high-precision model of ±1Pa, and controller 430 integrates PID algorithm and fuzzy logic to adapt to the ship's rocking conditions.

[0070] An embodiment of the present invention provides a ship LNG dual-fuel ventilation system and control method thereof, comprising: an airlock isolation unit 100, a mechanical air supply module 200, a natural exhaust duct 300, a dynamic pressure management system 400, and a fault emergency unit 500. The airlock isolation unit 100 is located in the transition area between the LNG fuel tank and the engine room, and its physical isolation structure complies with the requirements of the IGF Code. The mechanical air supply module 200 includes a main fan 210 and a backup fan 220 arranged in parallel, and is equipped with a dual power supply interface 230 to connect the system's main power supply and emergency power supply. The natural exhaust duct 300 is equipped with an explosion-proof gravity baffle 310 and a fire damper 320. The dynamic pressure management system 400 includes a pressure sensor 410, a flow switch 420, and a controller 430 to maintain a positive pressure value of ≥50Pa between the airlocks in real time. The fault emergency unit 500 includes a power monitoring module 510 and a fan switching actuator 520.

[0071] The technical solution of this invention, through multi-level control logic, dual-circuit redundant power supply, and intelligent pressure management, addresses the problems of insufficient dynamic pressure control, weak redundancy design, and delayed emergency response in traditional LNG ship ventilation systems. It also effectively addresses the design difficulties of the power supply, signal framework, and external system interface of the LNG supply control system for single- and dual-fuel vessels, meeting the requirements of relevant classification societies and regulations, reducing the number of unreasonable and non-standard system designs by equipment manufacturers, and providing valuable experience for the design of control systems for subsequent LNG-fueled vessels.

[0072] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A ship LNG dual-fuel ventilation system, characterized in that: The system comprises: an airlock isolation unit (100), a mechanical air supply module (200), a natural exhaust channel (300), a dynamic pressure management system (400) and a fault emergency unit (500); The airlock isolation unit (100) is arranged in the transition area between the LNG fuel tank and the engine room, and its physical isolation structure complies with the requirements of the IGF Code; The mechanical air supply module (200) includes a main fan (210) and a backup fan (220) arranged in parallel, and is equipped with a dual-circuit power supply interface (230) for connecting the main power supply and the emergency power supply of the system; The natural exhaust passage (300) is provided with an explosion-proof gravity baffle (310) and a fire damper (320); The dynamic pressure management system (400) includes a pressure sensor (410), a flow switch (420) and a controller (430), and maintains a positive pressure value of ≥50 Pa in the airlock in real time; The fault emergency unit (500) comprises a power supply monitoring module (510) and a fan switching actuator (520).

2. A ship LNG dual-fuel ventilation system according to claim 1, characterized in that: The dual-circuit power supply interface (230) comprises: a main distribution board direct power supply line and an emergency generator power supply line connected via a transfer switch, and an electrical interlocking device (231) is provided between the two power supply lines.

3. A ship LNG dual-fuel ventilation system according to claim 1, characterized in that: The dynamic pressure management system (400) is configured with three levels of control logic: First-level response: triggering the frequency conversion speed regulation of the main fan (210) through the pressure sensor (410); Second-level response: when the pressure value is lower than 45 Pa, the standby fan (220) is started to operate in parallel; Level 3 response: When the pressure value is lower than 40Pa for 30 seconds, the hazardous area isolation signal is activated.

4. A ship LNG dual-fuel ventilation system according to claim 1, characterized in that: The fault emergency unit (500) is provided with a dual fault detection mechanism, including: a fan mechanical fault diagnosis module (511) and a power supply fault diagnosis module (512); The fan mechanical fault diagnosis module (511) is based on current fluctuation detection, and the power supply fault diagnosis module (512) is based on voltage phase detection. The two modules trigger the switching actuator (520) through an OR logic relationship.

5. A method for controlling a ship LNG dual-fuel ventilation system, based on a ship LNG dual-fuel ventilation system according to any one of claims 1 to 4, characterized in that: The control method comprises: S101, when the system is started, the main fan (210) is started first, and a reference pressure curve is established through the pressure sensor (410); S102, comparing the deviation between the current pressure value and the set threshold value (50±5Pa) in real time; S103, when the difference exceeds 10%, starting the standby fan (220) for parallel compensation operation; S104: When an abnormality in the main power supply is detected, the system switches to the emergency power supply within 0.3s to 0.5s. S105: When the pressure value is lower than 35Pa for 30 seconds, an area isolation command is sent to the ship's central control system.

6. A method for controlling a ship LNG dual-fuel ventilation system according to claim 5, characterized in that: In step S103, a nonlinear compensation algorithm is set, specifically satisfying the following functional relationship: Q_ 补偿 =K1×ΔP+K2×(ΔP)^2 Among them, Q_ 补偿 To compensate for the air volume, ΔP is the pressure deviation, K1 = 0.8 ~ 1.2, K2 = 0.05 ~ 0.

15.

7. A method for controlling a ship LNG dual-fuel ventilation system according to claim 5, characterized in that: The power switching operation in step S104 includes a pre-synchronization detection phase, specifically including: Detect the voltage amplitude difference of the emergency power supply ≤±5%; Detection frequency difference ≤±0.2Hz; The phase angle difference is detected to be ≤±5 degrees, and seamless switching is performed when all conditions are met.

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