Ballast tank overpressure prevention system and overpressure prevention method of compressed air deballasting system

Abstract

The present invention discloses a ballast tank overpressure prevention system of a compressed air ballast discharge system, comprising a ballast system control station, a ballast tank, and an air compressor; the air compressor is connected to an air inlet at the top of the ballast tank through a compressed air pipeline, a compressed air remote control valve is provided on the compressed air pipeline, a ballast remote control valve is provided at the bottom of the ballast tank, a ballast pipeline connected to the ballast remote control valve 5 is provided at the bottom of the ballast tank, a top pressure sensor for measuring the top pressure value P1 of the ballast tank is provided at the top of the ballast tank; a bottom main pressure sensor for measuring the bottom pressure value P2 of the ballast tank is provided at the bottom of the ballast tank; a draft pressure sensor for measuring the draft pressure value P4 of the ship is provided at the bottom of the outer wall of the ballast tank; and a controller is provided at the ballast system control station. The present invention also discloses an overpressure prevention method of the system.

Description

Technical Field

[0001] The invention relates to an overpressure prevention system for a ballast tank of a compressed air ballast removal system and an overpressure prevention method thereof. Background Art

[0002] The compressed air deballasting system is a deballasting method commonly used by semi-submersible vessels, multi-functional bottom-supported platforms and other types of ships. According to the needs of ship (platform) operation, the ballast tanks of the entire ship are injected or discharged to adjust the draft of the ship and the longitudinal and transverse stability and safe metacentric height of the hull, reduce the vibration of the hull, and improve the seaworthiness of the empty tank. Therefore, the compressed air deballasting system is the core system of the platform's sinking and floating operations, and is also a key system to ensure that the hull structure does not bear additional loads.

[0003] Since the external water level is higher than the liquid level in the ballast tank, the main method for this type of ship to discharge ballast water is: the air compressor injects compressed air into the closed ballast tank through valves and pipelines, and at the same time opens the ballast valve at the bottom of the ballast tank, and uses the continuously input compressed air to discharge the ballast water in the tank through the valve and pipeline at the bottom.

[0004] The above-mentioned traditional compressed air deballasting system has no protective measures to prevent the ballast tank from overpressure on the deballasting tank, valve remote control, and liquid level telemetry console. Under normal operation, the pressure on the ballast tank will not exceed its structural design strength, that is, there is no risk of structural deformation. However, if there is an error in operation or the ballast valve fails to open normally, compressed air will continue to be injected into the closed ballast tank, and the ballast tank structure will be overpressured and deformed, and ultimately endanger the safety of the ship. In other words, the operator is not allowed to make any mistakes in the traditional deballasting process. Once a mistake is made, the ballast tank may be overpressured, the hull structure may be deformed, and the safety of the ship may be endangered. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an overpressure prevention method for a ballast tank overpressure prevention system of a compressed air deballasting system.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: an anti-overpressure method for the ballast tank anti-overpressure system of the above compressed air deballasting system, wherein the ballast tank anti-overpressure system includes a ballast system control station, a ballast tank, and an air compressor;

[0007] The air compressor is connected to the air inlet at the top of the ballast tank through a compressed air pipeline. A compressed air remote control valve is provided on the compressed air pipeline. A ballast remote control valve is provided at the bottom of the ballast tank. A ballast pipeline connected to the ballast remote control valve 5 is provided at the bottom of the ballast tank. A top pressure sensor for measuring the top pressure value P1 of the ballast tank is provided at the top of the ballast tank. A bottom main pressure sensor for measuring the bottom pressure value P2 of the ballast tank is provided at the bottom of the ballast tank. A draft pressure sensor for measuring the draft pressure value P4 of the ship is provided at the bottom of the outer wall of the ballast tank.

[0008] The ballast system control station is provided with a controller, which is respectively connected to the compressed air remote control valve, the ballast remote control valve, the top pressure sensor, the bottom main pressure sensor, and the draft pressure sensor through control cables for remote control; a bottom backup pressure sensor is provided above the bottom main pressure sensor in the ballast tank; the ballast system control station is provided with a display, which is connected to the controller through a control cable; the overpressure prevention method specifically includes the following steps:

[0009] S1: The computer system obtains the bottom pressure value P2 from the bottom main pressure sensor or obtained by equivalent calculation and the ship draft pressure value P4 from the draft pressure sensor through the controller;

[0010] S2: The computer system calculates the pressure value P5 that the bulkhead structure is subjected to, where P5 = P2-P4;

[0011] S3: Continuously compare the pressure value P5 borne by the bulkhead structure with the pre-set design pressure value P that the ballast tank structure can withstand:

[0012] If the difference between the design pressure value P that the ballast tank structure can withstand and the calculated value of the pressure value P5 actually borne by the bulkhead structure is greater than the set value, the computer system does not take any action and continues to monitor; if the difference between the design pressure value P that the ballast tank structure can withstand and the calculated value of the pressure value P5 actually borne by the bulkhead structure is less than or equal to the set value, the computer system outputs an emergency alarm signal through the controller in the ballast system control station, and after 20 seconds, the controller performs an open and closed status detection on the compressed air remote control valve. If it is detected that the compressed air remote control valve is closed, the alarm ends; if the compressed air remote control valve is still in the open state, the system automatically issues a command to close the compressed air remote control valve on the compressed air pipeline, and the controller outputs a pending status alarm signal.

[0013] As a preferred solution, the controller outputs an emergency alarm signal to the display.

[0014] As a preferred solution, the controller outputs a pending status alarm signal to the display and displays an indication that the compressed air valve is closed.

[0015] The beneficial effects of the present invention are:

[0016] This anti-overpressure system realizes real-time monitoring and adjustment of the actual pressure in the ballast tank, effectively avoiding the risk of overpressure in the ballast tank and deformation of the hull due to negligence of the operator, making such systems safer and more reliable during operation, and fundamentally playing the role of protecting the ballast tank.

[0017] Since the bottom main pressure sensor is provided with a redundant bottom backup pressure sensor, when the bottom main pressure sensor fails, the bottom backup pressure sensor comes into play and can replace the bottom main pressure sensor to measure the bottom pressure of the ballast tank to ensure the normal operation of the system.

[0018] This overpressure prevention method compares the difference P5 between the bottom pressure value P2 of the ballast tank and the draft pressure value P4 with the bulkhead structure design pressure value P in real time. The system defaults that the absolute value of the comparison value shall not be less than or equal to a certain parameter. When the actual pressure value of the ballast tank is close to the structural design value, the computer on the valve remote control and liquid level telemetry console automatically outputs an alarm signal to the outside, and automatically closes the compressed air valve after 20 seconds to stop injecting compressed air into the tank. The system monitors the pressure in the ballast tank in real time and issues an alarm in the shortest time in case of an unexpected situation. It has a fast response time and high sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The figure is a schematic structural diagram of a ballast tank overpressure prevention system of a compressed air deballasting system in an embodiment of the present invention.

[0020] Figure 2 The present invention is a flow chart of the control of a ballast tank overpressure prevention system of a compressed air deballasting system in an embodiment of the present invention.

[0021] Figure 1-Figure 2 middle:

[0022] 1. Ballast tank 2. Air compressor 3. Compressed air remote control valve

[0023] 4. Compressed air pipeline 5. Ballast remote control valve 6. Ballast pipeline

[0024] 7. Top pressure sensor 8. Bottom main pressure sensor 9. Draft pressure sensor

[0025] 10. Control cable 11. Controller 12. Display

[0026] 13. Bottom spare pressure sensor DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0028] like Figure 1 As shown, the ballast tank overpressure prevention system of the compressed air deballasting system includes a ballast system control station, a ballast tank 1, and an air compressor 2;

[0029] The air compressor 2 is connected to the air inlet at the top of the ballast tank 1 through a compressed air pipeline 4, a compressed air remote control valve 3 is provided on the compressed air pipeline 4, a ballast remote control valve 5 is provided at the bottom of the ballast tank 1, a ballast pipeline 6 connected to the ballast remote control valve 5 is provided at the bottom of the ballast tank 1, a top pressure sensor 7 for measuring the top pressure value P1 of the ballast tank 1 is provided at the top of the ballast tank 1; a bottom main pressure sensor 8 for measuring the bottom pressure value P2 of the ballast tank 1 is provided at the bottom of the ballast tank 1; a draft pressure sensor 9 for measuring the draft pressure value P4 of the ship is provided at the bottom of the outer wall of the ballast tank 1; a bottom backup pressure sensor 13 is provided in the ballast tank 1 above the bottom main pressure sensor 8.

[0030] The ballast system control station is provided with a controller 11 and a display 12. The display 12 is connected to the controller 11 via a control cable 10. The controller 11 is respectively connected to the compressed air remote control valve 3, the ballast remote control valve 5, the top pressure sensor 7, the bottom main pressure sensor 8, and the draft pressure sensor 9 via the control cable 10 for remote control.

[0031] like Figure 2 As shown, a method for preventing overpressure of a ballast tank overpressure prevention system of the compressed air deballasting system specifically comprises the following steps:

[0032] S1: The computer system obtains the bottom pressure value P2 from the bottom main pressure sensor 8 or obtained by equivalent calculation and the ship draft pressure value P4 from the draft pressure sensor 9 through the controller 11;

[0033] Calculation method of ballast tank 1 bottom pressure value P2:

[0034] When the bottom main pressure sensor 8 works normally, the top pressure sensor 7 on the top of the ballast tank 1 obtains the pressure value corresponding to the compressed air pressure value P1 plus the liquid level height H in the ballast tank 1, that is, P2=P1+ρgH (wherein, P2 and P1 are in Pascals; ρ represents liquid density, in kilograms per cubic meter; g represents gravity acceleration, g=9.8N / kg; H is in meters)

[0035] When the bottom main pressure sensor 8 fails, the compressed air pressure value P1 at the top of the ballast tank 1 plus the pressure value P3 of the bottom backup pressure sensor 13 and the pressure value corresponding to the liquid level height △h between the bottom backup pressure sensor 13 and the bottom main pressure sensor 8 in the ballast tank 1, that is, P2 = P1 + P3 + ρg△h;

[0036] S2: The computer system calculates the pressure value P5 that the bulkhead structure is subjected to; P5 = P2-P4;

[0037] S3: Continuously compare the pressure value P5 borne by the bulkhead structure with the pre-set design pressure value P that the ballast tank structure can withstand:

[0038] If the difference between the design pressure value P that the ballast tank structure can withstand and the calculated pressure value P5 that the bulkhead structure actually withstands is greater than the set value of 0.1 bar (i.e. P-(P2-P4)>0.1), the system will not take any action and continue monitoring;

[0039] If the difference between the design pressure value P that the ballast tank structure can withstand and the calculated pressure value P5 that the bulkhead structure actually withstands is less than or equal to the set value of 0.1 bar (that is, P-(P2-P4)≤0.1), the system will output an alarm signal to the display 12 through the controller 11 in the ballast system control station, and after 20 seconds, the controller 11 will detect the open and closed status of the compressed air remote control valve 3. If it is detected that the compressed air remote control valve 3 is closed, the alarm will end; if the compressed air remote control valve 3 is still in the open state, the system will automatically issue a command to close the compressed air remote control valve 3 on the compressed air pipeline 4, and the controller 11 will output an alarm signal to the display 12, and display an explanation that the compressed air valve has been closed.

[0040] The above-mentioned embodiments are only illustrative of the principles and effects of the invention, as well as some embodiments of its application, and are not intended to limit the invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the invention, and all of these belong to the protection scope of the invention.

Claims

1. A method for preventing overpressure of a ballast tank overpressure prevention system of a compressed air deballasting system, wherein the ballast tank overpressure prevention system comprises a ballast system control station, a ballast tank, and an air compressor; The air compressor is connected to the air inlet at the top of the ballast tank through a compressed air pipeline. A compressed air remote control valve is provided on the compressed air pipeline. A ballast remote control valve is provided at the bottom of the ballast tank. A ballast pipeline connected to the ballast remote control valve 5 is provided at the bottom of the ballast tank. A top pressure sensor for measuring the top pressure value P1 of the ballast tank is provided at the top of the ballast tank. A bottom main pressure sensor for measuring the bottom pressure value P2 of the ballast tank is provided at the bottom of the ballast tank. A draft pressure sensor for measuring the draft pressure value P4 of the ship is provided at the bottom of the outer wall of the ballast tank. The ballast system control station is provided with a controller, which is respectively connected to the compressed air remote control valve, the ballast remote control valve, the top pressure sensor, the bottom main pressure sensor, and the draft pressure sensor through control cables for remote control; a bottom backup pressure sensor is provided above the bottom main pressure sensor in the ballast tank; the ballast system control station is provided with a display, which is connected to the controller through a control cable; The overpressure prevention method specifically includes the following steps: S1: The computer system obtains the bottom pressure value P2 from the bottom main pressure sensor or obtained by equivalent calculation and the ship draft pressure value P4 from the draft pressure sensor through the controller; S2: The computer system calculates the pressure value P5 that the bulkhead structure is subjected to, where P5 = P2 - P4; S3: Continuously compare the pressure value P5 borne by the bulkhead structure with the pre-set design pressure value P that the ballast tank structure can withstand: If the difference between the design pressure value P that the ballast tank structure can withstand and the calculated value of the pressure value P5 actually borne by the bulkhead structure is greater than the set value, the computer system does not take any action and continues to monitor; if the difference between the design pressure value P that the ballast tank structure can withstand and the calculated value of the pressure value P5 actually borne by the bulkhead structure is less than or equal to the set value, the computer system outputs an emergency alarm signal through the controller in the ballast system control station, and after 20 seconds, the controller performs an open and closed status detection on the compressed air remote control valve. If it is detected that the compressed air remote control valve is closed, the alarm ends; if the compressed air remote control valve is still in the open state, the system automatically issues a command to close the compressed air remote control valve on the compressed air pipeline, and the controller outputs a pending status alarm signal.

2. The method for preventing overpressure of a ballast tank overpressure prevention system of a compressed air deballasting system according to claim 1, characterized in that: The controller outputs an emergency state alarm signal to the display.

3. The overpressure prevention method of the ballast tank overpressure prevention system of the compressed air deballasting system according to claim 2, characterized in that: The controller outputs a to-be-checked status alarm signal to the display and displays an indication that the compressed air valve has been closed.

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