A method for detecting leakage of marine low-flash-point and toxic fuel pipelines

Abstract

The present invention relates to the technical field of marine fuel pipelines, and more specifically, to a method for leak detection in marine low-flashpoint, toxic fuel delivery pipelines. The method comprises planning a pipeline installation path, welding an inner pipe in sections, sealing and welding an outer pipe to the outside of the inner pipe, filling the space between the inner and outer pipes with nitrogen, installing a pressure sensor in the outer pipe, installing an inflation valve and an air release valve on the pipe walls at both ends of the outer pipe, providing a liquid reservoir at a low position along the installation direction of the outer pipe body, installing a liquid level sensor and a first gas sensor in the reservoir, and installing a second gas sensor in the pipe below the air release valve. When the pressure sensor detects a pressure drop, a controller issues a fault signal, halting fuel delivery, and determining the leakage status of the inner and outer pipes based on the detection results of the liquid level sensor, the first sensor, and the second sensor. The present invention provides a method for leak detection in double-walled pipes that is simple in structure, does not require the installation of an air duct, and can be used to detect leaks in the inner and outer pipes.

Description

Technical Field

[0001] The invention relates to the technical field of marine fuel pipelines, in particular to a leakage detection method for marine low-flash-point and toxic fuel delivery pipelines. Background Art

[0002] As we all know, in order to meet the emission standards of nitrogen oxides and sulphides, the shipping industry often equips newly built ships with dual-fuel systems. Methanol is the preferred alternative energy source for fuel oil in dual-fuel systems due to its economic and environmental performance. Methanol has a low flash point and toxicity. To ensure the safety of methanol fuel transportation, double-walled pipes are usually required for fuel transportation pipelines. Conventional double-walled pipes include an inner pipe for transmitting fuel and an outer pipe for ventilation. Through the ventilation double-walled pipe, the fan blows the wind from the safe area through the double-walled pipe interlayer and discharges it to the safe area. In the event of a leak, the leaked methanol will be released into a safe open area, thereby protecting the engine room area.

[0003] However, this solution requires the fans to run continuously, which is not conducive to energy conservation and emission reduction on ships; equipment with moving parts has relatively high maintenance costs; ships need to be equipped with air ducts, which increases the workload of shipyard design and construction, and the shipowner has to make a large initial investment; and when a fuel leak occurs, it is impossible to determine whether the leak is from the inner or outer pipe, and the double-wall pipe cannot be maintained in time. Large amounts of methanol leakage will increase safety hazards near the fuel pipeline. Summary of the Invention

[0004] The purpose of the present invention is to solve the above-mentioned deficiencies in the prior art and to provide a method which has a simple structure, does not require the installation of air ducts, and can perform leakage detection on the inner and outer tubes of a double-walled tube.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A method for leak detection of a marine low-flashpoint, toxic fuel delivery pipeline comprises the following steps:

[0007] Step 1. Plan the pipeline installation path according to the locations of the gas supply device and the gas consumption device, weld the inner pipe in sections, and weld the outer pipe to the outside of the inner pipe; open detection ports on the outer pipe corresponding to the segmented welding points of the inner pipe, and there are four detection ports, which are evenly distributed on the outer pipe along the circumference of the outer pipe. The detection ports are threaded ports and the outer sides of the detection ports are sealed with top screw threads. The outer pipe is opened at the lowest position along the pipeline installation path and a liquid accumulation pool is welded. Branch pipes are welded at both ends of the outer pipe and an inflation valve and an air release valve are installed. A liquid level sensor is installed at the bottom of the liquid accumulation pool, a first gas sensor is installed on the side wall of the liquid accumulation pool, a second gas sensor is installed in the branch pipe below the air release valve, and a pressure sensor is installed on the inner wall of the outer pipe to obtain the required pipeline body;

[0008] Step 2: Lay and install the pipeline body made in Step 1 along the pipeline installation path. The two ends of the pipeline body are respectively connected to the gas supply device and the gas consumption device. The pressure sensor, the liquid level sensor, the first gas sensor, and the second gas sensor are all electrically connected to the controller. Nitrogen is filled between the inner and outer tubes through the inflation valve and reaches the set value of the pressure sensor. The pressure value set by the pressure sensor is greater than the pressure value of the fuel in the inner tube.

[0009] Step 3: If the pressure sensor detects that the pressures in the inner and outer pipes remain unchanged, the pipeline body is operating normally without leakage. If the pressure sensor detects a pressure drop between the inner and outer pipes, it indicates that there is a leak in the inner or outer pipe. The controller issues a fault signal, and the gas supply device stops supplying fuel to the gas user. The leakage of the inner and / or outer pipe is determined based on the detection results of the liquid level sensor, the first sensor, and the second sensor. The specific judgment results are as follows:

[0010] a. If the liquid level sensor sends out an alarm signal, there is liquid leakage in the inner tube;

[0011] b. If the first gas sensor sends out an alarm signal, there is a mist liquid leak in the inner tube;

[0012] c. If both the liquid level sensor and the first gas sensor send out alarm signals, the inner tube liquid is leaking and the mist liquid is leaking simultaneously;

[0013] d. If neither the liquid level sensor nor the first gas sensor gives an alarm, open the vent valve and the inflation valve to replace the nitrogen between the inner and outer tubes with new nitrogen. If the second gas detector gives an alarm signal at this time, there is a slight mist-like liquid leakage in the inner tube.

[0014] e. If the liquid level sensor, the first sensor, and the second sensor between the inner and outer tubes after nitrogen replacement do not alarm, then there is no leakage in the inner tube and there is leakage in the outer tube.

[0015] If the result of step three of the present invention is e, helium is filled between the inner and outer tubes through the inflation valve to replace the nitrogen between the inner and outer tubes, the weld of the outer tube and the sealing installation points of each accessory and the outer tube are detected by a gas detector, the leakage position is diagnosed by the gas sensor, and the pipeline body is disassembled to repair the leakage position by repair welding; if the result of step three is any one of abcd, the top screw on the detection port is opened, the weld of the inner tube inside the detection port is detected by the gas detector, the leakage position is diagnosed by the gas detector, and the pipeline body is disassembled, and the leakage position is repaired by repair welding through the detection port. After the repaired pipeline body is installed and filled with nitrogen, the pressure sensor detects a pressure drop between the inner and outer tubes, and it is determined that the outer tube is leaking, and the above-mentioned processing method of the determination result e is repeated.

[0016] In step one of the present invention, there are multiple low points on the outer tube along the pipeline installation path, each low point is opened and a liquid pool is welded, a liquid level sensor is installed at the bottom of each liquid pool, and a first gas sensor is installed on the side wall of the liquid pool.

[0017] In step one of the present invention, a drain valve is installed at the bottom of the liquid accumulation pool through a branch line. In step three, if the result is any one of ac, the pipeline body is disassembled, the drain valve is opened, and the liquid in the liquid accumulation pool is drained.

[0018] The beneficial effects of this patent are as follows:

[0019] This patent ensures the safe operation of fuel transportation by filling nitrogen between the inner and outer pipes for protection. Compared with traditional ventilation solutions, there is no need to install additional fans and air ducts, which reduces the design and construction workload and thus reduces the shipowner's initial investment. This design has low cost, is easy to install and easy to maintain. In addition, the nitrogen pressure value between the inner and outer pipes is automatically monitored. When the pressure drops, it proves that there is a leak in the inner or outer pipe. The controller sends a fault signal and the gas supply device stops delivering fuel to the gas user. The leakage of the inner and / or outer pipe is judged based on the detection results of the liquid level sensor, the first sensor and the second sensor. The pipeline can be quickly and effectively leak detected and maintained to avoid the hazards of methanol leakage and ensure the safety of fuel transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the marine fuel delivery pipeline of the present invention.

[0021] Figure 2 It is a cross-sectional view of the pipe body at the inner pipe welding point of the present invention.

[0022] Figure 3 It is a schematic diagram of the connection between the controller of the present invention and each sensor.

[0023] Figure 4 The present invention is a flow chart of a method for detecting leakage of a marine fuel delivery pipeline.

[0024] Figure numerals: 1. Outer tube; 2. Inner tube; 3. Air supply device; 4. Air using device; 5. Pressure sensor; 6. Inflation valve; 7. Deflation valve; 8. Liquid level sensor; 9. First gas sensor; 10. Second gas sensor; 11. Liquid accumulation pool; 12. Top screw; 13. Drain valve; 14. Controller. DETAILED DESCRIPTION

[0025] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0026] like Figure 1-4 As shown, a method for leak detection of a marine low-flashpoint, toxic fuel delivery pipeline comprises the following steps:

[0027] 1 and 2. The air filter 1 is connected to the air filter 1 through a through hole in the air filter 1 , so that the air filter 1 is kept in the air filter 1 and the air filter 1 is kept in the air filter 1 .

[0028] Step 2: Lay and install the pipeline body made in Step 1 along the pipeline installation path. The two ends of the pipeline body are respectively connected to the gas supply device 3 and the gas use device 4. The pressure sensor 5, the liquid level sensor 8, the first gas sensor 9 and the second gas sensor 10 are all electrically connected to the controller 14. Nitrogen is filled between the inner and outer tubes through the inflation valve 7 and reaches the set value of the pressure sensor 5. The pressure value set by the pressure sensor 5 is greater than the pressure value of the fuel in the inner tube 2.

[0029] Step three, if the pressure sensor 5 detects that the pressure in the inner and outer tubes remains unchanged, the pipeline body is operating normally without leakage; if the pressure sensor 5 detects a pressure drop between the inner and outer tubes, it proves that there is a leak in the inner tube 2 or the outer tube 1, and the controller 14 sends a fault signal, the gas supply device 3 stops delivering fuel to the gas device 4, and the leakage of the inner tube 2 and / or the outer tube 1 is judged according to the detection results of the liquid level sensor 8, the first sensor 9 and the second sensor 10; by filling nitrogen between the inner and outer tubes for protection, the safe operation of the fuel delivery can be guaranteed. The entire pipeline body has a simple structure and does not require the installation of additional motors and air ducts. Its installation cost is low and it is easy to maintain. At the same time, by monitoring the nitrogen pressure, when the pressure drops, the controller 14 controls the fuel delivery to stop, ensuring the safe delivery of the fuel. The liquid level sensor 8, the first gas sensor 9 and the second gas sensor 10 can provide timely feedback on the leakage of the inner tube, and the specific judgment results are as follows:

[0030] a. If the liquid level sensor sends out an alarm signal, there is liquid leakage in the inner tube and the leakage level is high;

[0031] b. If the first gas sensor issues an alarm signal, there is a mist-like liquid leak in the inner tube, and the leakage level is medium;

[0032] c. If both the liquid level sensor and the first gas sensor send out alarm signals, the inner tube liquid leaks and the mist liquid leaks simultaneously, and the leakage level is the highest;

[0033] d. If neither the liquid level sensor nor the first gas sensor sounds an alarm, open the vent valve and the inflation valve to replace the nitrogen between the inner and outer tubes with new nitrogen. If the second gas detector sounds an alarm at this time, there is a slight mist-like liquid leak in the inner tube, and the leakage level is the lightest.

[0034] e. If the liquid level sensor, the first sensor, and the second sensor after nitrogen replacement between the inner and outer tubes all do not alarm, then there is no leakage in the inner tube and there is leakage in the outer tube. By identifying the leakage levels, corresponding treatment measures can be taken.

[0035] If the result in step three is e, helium is filled between the inner and outer tubes through the inflation valve to replace the nitrogen between the inner and outer tubes, and the outer tube weld and the sealing installation points of each accessory and the outer tube are detected with a gas detector. The leakage position is diagnosed by the gas sensor, and the pipeline body is disassembled to repair the leakage position by repair welding. If the result in step three is any one of abcd, the top screw on the detection port is opened, the inner tube weld inside the detection port is detected with a gas detector, the leakage position is diagnosed by the gas detector, and the pipeline body is disassembled to repair the leakage position by repair welding through the detection port. After the repaired pipeline body is installed and filled with nitrogen, the pressure sensor detects a pressure drop between the inner and outer tubes, and it is determined that the outer tube is leaking, and the above processing method for the determination result e is repeated. The design of the detection port is that after determining that the inner tube 2 is leaking, the weld of the inner tube 2 corresponding to each detection port can be detected through the gas detector, so as to quickly find the leakage location (due to the special material of the pipeline used for fuel transportation, the weld is a common leakage location), and the four detection ports can ensure that the gas detector detects the entire annular weld. At the same time, when repairing, it is only necessary to insert the welding rod from the detection port to repair the weld leak without disassembling the outer tube 1, thereby reducing the workload; the gas detector is a prior art, and sensors can be installed inside it as needed to detect the corresponding gas in a matching manner. For example, in this embodiment, a methanol sensor and a helium sensor can be installed in the gas sensor at the same time, and the first gas sensor and the second gas sensor are both corresponding methanol sensors, and their internal structure and principle are not elaborated.

[0036] In step 1, the outer tube 1 has multiple low points along the pipeline installation path. A hole is opened at each low point and a liquid reservoir 11 is welded to it. A liquid level sensor 8 is installed at the bottom of each liquid reservoir 11, and a first gas sensor 9 is installed on the sidewall of each liquid reservoir 11. Because the installation path on a ship is complex and varied, installing liquid reservoirs 11 at these low points improves detection accuracy.

[0037] In step one, a drain valve 13 is installed at the bottom of the liquid accumulation pool 11 through a branch line. In step three, if the result is any one of ac, the pipeline body is disassembled, the drain valve 13 is opened, and the liquid in the liquid accumulation pool 11 is drained.

[0038] The leakage detection method of the present invention can judge the leakage of the inner tube 2 according to each sensor, so that when the controller 14 stops delivering fuel, a corresponding treatment plan can be made and the pipeline leakage point can be repaired in time.

Claims

1. A method for detecting leakage of a marine low-flashpoint, toxic fuel pipeline, characterized in that: The detection method steps are as follows: Step 1. Plan the pipeline installation path according to the locations of the gas supply device and the gas consumption device, weld the inner pipe in sections, and weld the outer pipe to the outside of the inner pipe; open detection ports on the outer pipe corresponding to the segmented welding points of the inner pipe, and there are four detection ports, which are evenly distributed on the outer pipe along the circumference of the outer pipe. The detection ports are threaded ports and the outer sides of the detection ports are sealed with top screw threads. The outer pipe is opened at the lowest position along the pipeline installation path and a liquid accumulation pool is welded. Branch pipes are welded at both ends of the outer pipe and an inflation valve and an air release valve are installed. A liquid level sensor is installed at the bottom of the liquid accumulation pool, a first gas sensor is installed on the side wall of the liquid accumulation pool, a second gas sensor is installed in the branch pipe below the air release valve, and a pressure sensor is installed on the inner wall of the outer pipe to obtain the required pipeline body; Step 2: Lay and install the pipeline body prepared in Step 1 along the pipeline installation path. The two ends of the pipeline body are respectively connected to the gas supply device and the gas consumption device. The pressure sensor, the liquid level sensor, the first gas sensor, and the second gas sensor are all electrically connected to the controller. Nitrogen is filled between the inner and outer tubes through the inflation valve to reach the set value of the pressure sensor. The pressure value set by the pressure sensor is greater than the pressure value of the fuel in the inner tube. Step 3: If the pressure sensor detects that the pressures in the inner and outer pipes remain unchanged, the pipeline body is operating normally without leakage. If the pressure sensor detects a pressure drop between the inner and outer pipes, it indicates that there is a leak in the inner or outer pipe. The controller issues a fault signal, and the gas supply device stops supplying fuel to the gas user. The leakage of the inner and / or outer pipe is determined based on the detection results of the liquid level sensor, the first sensor, and the second sensor. The specific judgment results are as follows: a. If the liquid level sensor sends out an alarm signal, there is liquid leakage in the inner tube and the leakage level is high; b. If the first gas sensor issues an alarm signal, there is a mist-like liquid leak in the inner tube, and the leakage level is medium; c. If both the liquid level sensor and the first gas sensor send out alarm signals, the inner tube liquid leaks and the mist liquid leaks simultaneously, and the leakage level is the highest; d. If neither the liquid level sensor nor the first gas sensor sounds an alarm, open the vent valve and the inflation valve to replace the nitrogen between the inner and outer tubes with new nitrogen. If the second gas detector sounds an alarm at this time, there is a slight mist-like liquid leak in the inner tube, and the leakage level is the lightest. e. If the liquid level sensor, the first sensor, and the second sensor between the inner and outer tubes after nitrogen replacement do not alarm, then there is no leakage in the inner tube and there is leakage in the outer tube.

2. A method for detecting leakage of a marine low-flashpoint, toxic fuel pipeline according to claim 1, characterized in that: If the result in step three is e, helium is filled between the inner and outer tubes through the inflation valve to replace the nitrogen between the inner and outer tubes, and the outer tube weld and the sealing installation points of each accessory and the outer tube are detected with a gas detector. The leakage position is diagnosed by the gas sensor, and the pipeline body is disassembled to repair the leakage position by repair welding. If the result in step three is any one of abcd, the top screw on the detection port is opened, the inner tube weld inside the detection port is detected with a gas detector, the leakage position is diagnosed by the gas detector, and the pipeline body is disassembled to repair the leakage position by repair welding through the detection port. After the repaired pipeline body is installed and filled with nitrogen, the pressure sensor detects a pressure drop between the inner and outer tubes, and it is determined that the outer tube is leaking, and the above processing method for the determination result e is repeated.

3. The method for leak detection of a marine low-flashpoint, toxic fuel pipeline according to claim 1, characterized in that: In step one, there are multiple low points on the outer tube along the pipeline installation path. A hole is opened at each low point and a liquid pool is welded. A liquid level sensor is installed at the bottom of each liquid pool, and a first gas sensor is installed on the side wall of the liquid pool.

4. The method for detecting leakage of a marine low-flashpoint, toxic fuel pipeline according to claim 2, characterized in that: In step one, a drain valve is installed at the bottom of the liquid accumulation pool through a branch line. In step three, if the result is any one of ac, the pipeline body is disassembled, the drain valve is opened, and the liquid in the liquid accumulation pool is drained.

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