A methanol filling system and inerting monitoring method

Abstract

The present invention provides a methanol filling system and an inerting monitoring method, which relate to the field of ship power and are used to provide a power source for ships. From the outer shell to the middle of the ship, there are ballast tanks, isolation tanks, at least one fuel tank and daily cabinets in sequence, and the ballast tanks, isolation tanks, at least one fuel tank and the part of the daily cabinet below the main deck form an enclosed structure with the main deck, so that after at least one of the daily cabinets, at least one fuel tank and isolation tank where fuel is stored is damaged, the ballast tank can finally be used to form a fuel leakage protection. Through the technical solution of the present invention, the part below the main deck forms a U-shaped enclosing structure. The U-shaped enclosing structure constitutes multiple fuel leakage protection, which controls the leakage within the designated area, prevents the fuel from threatening other safe areas of the ship, and further improves the safety of the ship.

Description

Technical Field

[0001] The present invention relates to the field of ship power, and in particular to a methanol filling system and an inerting monitoring method. Background Art

[0002] In response to the initial strategy for reducing greenhouse gas emissions from ships, the main engines of large ships have begun to be converted from traditional diesel and heavy oil to various clean and low-carbon energy sources. The main energy sources currently in use and development are LNG and LPG, but they are still fossil energy and can only be used as intermediate transitional carbon reduction solutions. At this time, methanol stands out and becomes a more ideal fuel that further meets zero emissions. From a full life cycle perspective, green methanol produced from biomass / direct air carbon capture can be considered to have 100% carbon reduction.

[0003] Among them, LNG is the abbreviation of liquefied natural gas, which is composed of 90% methane; LPG is the abbreviation of liquefied petroleum gas, which is composed of propane, butane and other hydrocarbons. LNG and LPG are gaseous at normal temperature and pressure, and need to be liquefied by lowering the temperature and / or increasing the pressure to reduce the volume for easy storage and transportation.

[0004] Methanol can be stored and transported in liquid form at room temperature and pressure, and has low inlet pressure to the main engine, making it a viable alternative fuel solution. However, inhalation of methanol can cause personal injury, and its vapor can form an explosive mixture with air. Therefore, the design of a ship's methanol piping system requires solutions for inerting, replacement, and leakage monitoring. Common methanol power system designs typically design the daily fuel tank as an independent cabinet placed on the main deck. This design generally has the following problems and disadvantages:

[0005] 1. Daily use cabinets are independent cabinets placed on the main deck, requiring a large space;

[0006] 2. After the pipeline system is inerted, only a single test is performed without continuous monitoring, making it impossible to detect safety hazards caused by subsequent leaks;

[0007] 3. Each time the fuel tank and daily cabinet are filled or unloaded, gas filling and overpressure release are required, which wastes nitrogen. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to reduce the problems of large space occupied by daily service tanks when methanol is used as fuel for ship propulsion, discontinuous monitoring of the pipeline system after inerting, and the need for gas filling and overpressure release each time the fuel tank and daily service tank are filled or unloaded, thereby wasting nitrogen. The purpose is to provide a methanol filling system and an inerting monitoring method to solve the above problems.

[0009] A methanol filling system for providing a power source for a ship comprises a ship and its hull, a ballast tank, at least one fuel tank, an isolation void tank and a service tank; the ballast tank, the isolation void tank, the at least one fuel tank and the service tank are arranged in sequence from the hull to the midship, and the ballast tank, the isolation void tank, the at least one fuel tank and the service tank below the main deck form an enclosed structure with the main deck, so that if at least one of the service tank, the at least one fuel tank and the isolation void tank where the fuel is stored is damaged, the ballast tank can ultimately be used to protect the fuel from leakage.

[0010] Furthermore, it also includes at least one filling station, which includes an evaporative gas pipe, a fuel filling pipe, a nitrogen pipe, an isolation control valve and a filter that are interconnected.

[0011] Furthermore, the evaporation gas pipe and the fuel filling pipe are both provided with nitrogen pipes to inert the interior of the evaporation gas pipe and the fuel filling pipe and reduce the oxygen content to less than 2% and the combustible gas to less than 20% LEL.

[0012] Furthermore, the at least one fuel tank and the daily cabinet are both provided with nitrogen pipes to inert the interior of the at least one fuel tank and the daily cabinet and reduce the oxygen content to less than 2% and the combustible gas to less than 20% LEL.

[0013] Furthermore, the at least one fuel tank and the daily cabinet are respectively equipped with at least one PV valve, which can automatically open or close according to the pressure difference between at least one fuel tank, isolation tank and ballast tank and the outside of the cabin to keep the pressure in the cabin stable within a specified range; when performing fuel filling operations, when the pressure in the cabin exceeds the specified range, the at least one PV valve is opened to restore the pressure in the cabin to the specified range.

[0014] Furthermore, the at least one fuel tank and the daily cabinet are respectively provided with pumps, and the at least one fuel tank and the daily cabinet are connected by a pipeline. A three-way valve is provided on the pipeline to keep the sum of the fuel liquid volume and the sum of the top gas volume in the at least one fuel tank and the daily cabinet unchanged through the opening and closing of the three-way valve and the transfer of the pump, or through natural opening and closing by gravity, and the PV valve does not need to be opened and closed.

[0015] Furthermore, the PV valves, each provided in the at least one fuel tank and the service tank, share a common pipeline. One end of the common pipeline is connected to a vent mast, and the other end is equipped with the flow valve, dry air pipe, and check valve. A gas detector is provided between the at least one PV valve and the vent mast for continuous monitoring. Nitrogen (not shown) enters through the dry air pipe, passes through the flow valve and check valve in sequence, inerting the pipeline and purging it, before being discharged to the vent mast. Inerting ceases when the gas detector detects an oxygen content below 2% and a flammable gas content below 20% LEL. The gas source is then switched from nitrogen to dry air, which enters through the dry air pipe, where the dry air flow rate is adjusted to a specified value by the flow valve. The dry air enters the dry air pipe, continuously ventilating the pipeline at a low rate, and is discharged through the vent mast. This ensures that if the at least one PV valve releases or leaks, the flammable gas in the tank is ventilated to the gas detector via the low-speed ventilation, allowing the gas detector to detect the release or leak as soon as possible. An alarm is triggered when the flammable gas concentration exceeds 20% LEL.

[0016] Furthermore, the flow rate of the dry air output after the flow valve is adjusted is set in a range of 0.5-2.8 m / s.

[0017] Another embodiment of the present invention provides an inerting monitoring method for a methanol filling system, which can be used in the methanol filling system of the above embodiment, comprising the following steps:

[0018] S1, nitrogen is introduced into at least one fuel tank, service tank, boil-off gas pipe and fuel filling pipe through a nitrogen pipe for inerting, and the displaced gas is discharged through a port or vent mast of at least one fuel filling station;

[0019] S2, fuel is injected into at least one fuel tank or daily cabinet through the fuel filling pipe at any filling station, and the nitrogen in the tank is discharged through the evaporation pipe through a third-party receiving device or through the vent mast by opening the control valve;

[0020] S3, after filling to the designated liquid level, the pipeline is first purged with nitrogen to blow the residual fuel in the pipeline to at least one fuel tank or daily cabinet. Then, after closing the control valve, the pipeline is again purged with nitrogen for inerting. The process stops when the oxygen content is less than 2% and the combustible gas is less than 20% LEL as measured by a portable detector (not shown), and the control valve is kept closed.

[0021] S4, dry air enters from the dry air pipe to continuously ventilate the pipeline at a low speed, and is discharged through the ventilation mast. The gas detector continuously monitors the pipeline.

[0022] Furthermore, the replaced air is required to have an oxygen content of less than 2% and a combustible gas content of less than 20% LEL.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] 1. The present invention provides a methanol filling system, in which the structure of the entire ship from the outer shell to the middle of the ship is composed of ballast tanks, isolation tanks, fuel tanks and daily cabinets in sequence, the top of which is kept horizontally arranged with the main deck, and the part below the main deck together forms a U-shaped enclosure structure. The U-shaped enclosure structure constitutes multiple fuel leakage protections, which controls the leakage within the designated area, avoids the fuel from posing a threat to other safe areas of the ship, and further improves the safety of the ship. In addition, an isolation control valve is provided between the fuel filling pipe and the methanol fuel tank to ensure that it is opened during filling and closed during non-operation. The filling station is equipped with an inert gas purge to ensure the safety of filling. The fuel tank and daily cabinet are arranged under the main deck to minimize the space they occupy on the main deck and facilitate the loading of cargo. When the fuel tank and daily cabinet are refilled or transferred to each other, gas circulation can be achieved through the three-way valve connecting the top of the tank, thereby avoiding the waste of nitrogen and saving costs. In addition, the fuel liquid can be circulated through the bottom connecting valve instead of the pump for transfer, which is flexible in configuration;

[0025] 2. The present invention provides an inerting monitoring method, in which a gas detector is provided on the PV valve outlet pipeline. The pipeline is first inerted with gas. After the combustible gas content is detected to be lower than 20% LEL, slow dry air is used to maintain continuous ventilation of the PV valve outlet pipeline to the ventilation mast. When the content exceeds 20% LEL, an alarm is triggered. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are provided for a better understanding of the present invention and do not constitute a limitation of the present invention.

[0027] Figure 1 is a schematic diagram of a front view of a methanol filling system according to one embodiment of the present invention;

[0028] Figure 2 is a schematic diagram of an AA section of a front view according to an embodiment of the present invention;

[0029] Figure 3 is a schematic diagram of a natural on-off function according to one embodiment of the present invention;

[0030] Figure 4 FIG. 4 is a flow chart of an inerting monitoring method for a methanol filling system according to an embodiment of the present invention.

[0031] Reference numerals:

[0032] 100-Ship, 101-Hull, 102-First fuel tank, 103-Second fuel tank, 104-Isolated void space, 105-Ballast tank, 106-Day service cabinet, 201-First fuel pump, 202-Second fuel pump, 203-Day service pump, 204-206-PV valve, 207-223-Control valve, 224-Flow valve, 230-234-Check valve, 225-226-Three-way valve, 251-Evaporative gas pipe, 252-Fuel filling pipe, 253-257-Pipeline, 290-Fuel supply unit, 270-Nitrogen pipe, 271-Dry air pipe, 272-Mast supply pipe, 273-Ventilation mast, 274-Filter, 281-Port filling station, 282-Starboard filling station, 300-Gas detector. DETAILED DESCRIPTION

[0033] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but are not to be construed as limiting the present invention.

[0034] like Figure 1 As shown, the present invention provides a methanol filling system for providing a power source for a ship 100, comprising the ship 100 and its hull 101, a ballast tank 105, at least one fuel tank, an isolation void tank 104 and a daily service tank 106; the hull 101 to the middle of the ship are the ballast tank 105, the isolation void tank 104, the at least one fuel tank and the daily service tank 106 in sequence, and the ballast tank 105, the isolation void tank 104, the at least one fuel tank and the daily service tank 106 below the main deck form an enclosed structure with the main deck, so that if at least one of the daily service tank 106, the at least one fuel tank and the isolation void tank 104 where the fuel is stored is damaged, the ballast tank 105 can finally form leakage protection for the fuel.

[0035] In some embodiments, at least one fuel tank, for example, two fuel tanks, such as Figure 1 and Figure 2As shown, a methanol filling system may include the following components: a ship 100; a hull 101; a first fuel tank 102; a second fuel tank 103; a first fuel pump 201; a second fuel pump 202; an isolation tank 104; a ballast tank 105; a daily cabinet 106; a daily pump 203; PV valves 204-206; control valves 207-223; a flow valve 224; a one-way valve 230-234; a three-way valve 225-226; an evaporative gas pipe 251; a fuel filling pipe 252; pipelines 253-257; a fuel supply unit 290; a nitrogen pipe 270; a dry air pipe 271; a main supply pipe 272; a vent mast 273; a port filling station 281; a starboard filling station 282 and a gas detector 300.

[0036] The valve 217 and the pipeline in which it is located are used to connect the pipeline 251 and the pipeline 253, and the pipeline 253 is connected to the ventilation mast 273.

[0037] The structure of the ship 100 is composed of a ballast tank 105 and an isolation void tank 104 from the hull 101 to the midship; a fuel tank and a daily service cabinet 106, the top of which is arranged horizontally with the main deck, and the part below the main deck together forms a U-shaped enclosing structure; a port filling station 281 and a starboard filling station 282 are arranged on the port and starboard sides of the main deck of the ship 100 respectively, for filling or unloading methanol fuel into or from the fuel tank and daily service cabinet 106.

[0038] In some embodiments, when damage to the service tank 106 causes a fuel leak, the fuel leaks into the first fuel tank 102 or the second fuel tank 103. Leaks from at least one of the fuel tanks leak into the cofferdam 104. Leaks from the cofferdam 104 leak into the ballast tank 105. These components, along with the main deck, form an enclosure (exemplarily a U-shaped enclosure) to provide multiple fuel leak protections, confining the leak to a designated area and preventing the fuel from posing a threat to other safe areas of the vessel 100.

[0039] The system further comprises at least one filling station, which comprises an evaporation gas pipe 251 , a fuel filling pipe 252 , a nitrogen pipe 270 , isolation control valves 207 - 223 and a filter 274 that are interconnected.

[0040] For example, Figure 2As shown, two refueling stations may be included: port refueling station 281 and starboard refueling station 282. Both port refueling station 281 and starboard refueling station 282 include components such as a vapor pressure pipe 251, a fuel refueling pipe 252, a nitrogen pipe 270, isolation control valves 207-223, and a filter 274. Refueling operations can be performed on either the port or starboard side depending on docking requirements. For example, when refueling on the port side is performed, the external refueling facility fuel pipe and vapor pressure recovery pipe are connected to the end interface of the fuel refueling pipe 252, where the filter 274 is located, and the end interface of the vapor pressure pipe 251, respectively. Fuel enters the fuel tank and service cabinet 106 through the fuel refueling pipe 252. This requires opening isolation control valves 207-223, specifically valves 210, 214, and 219, to maintain flow in the pipelines where the valves are located. When fuel enters the tank, the internal gas is discharged from the top. Valves 211, 216, and 222 must be opened to maintain flow in the pipelines where the valves are located. After the gas is discharged, it is transferred through vapor pipe 251 to the receiving device of the external filling facility (a third-party receiving device, not shown). Valves 233, 234, 230, and 231 are one-way valves to prevent gas from flowing back into the nitrogen system.

[0041] The evaporation gas pipe 251 and the fuel filling pipe 252 are both provided with nitrogen pipes to inert the interior of the evaporation gas pipe 251 and the fuel filling pipe 252 and reduce the oxygen content to less than 2% and the combustible gas to less than 20% LEL.

[0042] This prevents the natural air and fuel evaporated gas from forming an explosive mixture inside the evaporative gas pipe 251 and the fuel filling pipe 252. 100% LEL refers to the lower explosion limit of a gas. That is, when the concentration of a gas reaches this value, it may cause an explosion if it encounters an ignition source. LEL stands for "Lower Explosive Limit." So, 20% LEL means the gas concentration is 20% of its lower explosion limit. Therefore, if the gas concentration exceeds this value, necessary safety measures must be taken to prevent explosion accidents.

[0043] To achieve inerting, the methanol pipelines 253-256 system must be equipped with inert gas (e.g., nitrogen) injection and exhaust devices to reduce the methanol vapor-air mixture ratio and prevent explosions. During the loading, unloading, transportation, and storage of methanol, inert gas is used to displace and maintain pressure in the pipelines 253-256 and tanks.

[0044] The at least one fuel tank and the daily cabinet 106 are both provided with nitrogen pipes to inert the interior of the at least one fuel tank and the daily cabinet 106 and reduce the oxygen content to less than 2% and the combustible gas to less than 20% LEL.

[0045] This prevents the natural air and fuel vapor from forming an explosive mixture within the at least one fuel tank and the daily cabinet 106. 100% LEL refers to the lower explosion limit (LEL) of a gas. This means that when a gas reaches this concentration, it could potentially explode if exposed to an ignition source. Therefore, 20% LEL means the gas concentration is 20% of its lower explosion limit. Therefore, if the gas concentration exceeds this value, necessary safety measures must be taken to prevent explosions.

[0046] To achieve inerting, the methanol pipelines 253-256 system must be equipped with inert gas (e.g., nitrogen) injection and exhaust devices to reduce the methanol vapor-air mixture ratio and prevent explosions. During the loading, unloading, transportation, and storage of methanol, inert gas is used to displace, clean, and maintain pressure in pipelines 253-256 and the tank.

[0047] The at least one fuel tank and the daily cabinet 106 are respectively equipped with at least one PV valve 204-206, and the at least one PV valve 204-206 can be automatically opened or closed according to the pressure difference between at least one fuel tank, the isolation space 104 and the ballast tank 105 and the outside of the cabin, so as to keep the pressure in the cabin stable within a specified range; when performing fuel filling operations, when the pressure in the cabin exceeds the specified range, the at least one PV valve needs to be opened to restore the pressure in the cabin to the specified range.

[0048] Furthermore, the at least one PV valve has a common pipeline 253, one end of which is connected to the ventilation mast 273, and the other end is installed with the flow valve 224, the dry air pipe 271 and the one-way valve 232. A gas detector is provided between the at least one PV valve 204-206 and the ventilation mast 273 and is continuously monitored. Nitrogen (not shown) enters through the dry air pipe 271, and inertes and blows the pipeline 253 through the flow valve 224 and the one-way valve 232 in turn and discharges it to the ventilation mast 273. When the gas detector 300 detects that the oxygen content is lower than 2% and the combustible gas content is lower than 20% LEL, the inerting stops. Then the gas source is switched from nitrogen to dry air and enters from the dry air pipe 271. The dry gas is adjusted to a specified flow rate through the flow valve 224, and enters from the dry air pipe 271 to continuously maintain micro-ventilation of the pipeline 253, and is discharged through the ventilation mast 273. In this way, when at least one PV valve 204-206 releases or leaks, the combustible gas in the tank is blown to the gas detector 300 by the micro-ventilation, so that the gas detector 300 can detect the release or leakage of combustible gas as early as possible and issue an alarm when the combustible gas concentration is detected to be higher than 20% LEL.

[0049] like Figure 1 and Figure 2As shown, PV valves 204-206 are installed on the fuel tank and the daily cabinet 106 respectively. The three PV valves 204-206 are connected to a common pipeline 253, and the pipeline 253 is connected to a ventilation mast 273 set at a high place. For safety reasons, the ventilation mast 273 is installed on a platform next to the chimney, and the dotted range of its dangerous area does not overlap with the chimney exhaust area.

[0050] During refueling operations, if the external refueling facility is not equipped with a receiving device (a third-party receiving device, not shown), the gas in the cabin top opens valves 211, 216, and 222, passes through the evaporative gas pipe 251, and then passes through the opened control valve 217 and the pipeline it is located in, and then is discharged through pipeline 253 and vent mast 273. In an emergency, PV valves 204-206 can also be triggered to release the gas to the vent mast 273 for discharge.

[0051] PV valves 204-206, short for pressure-vacuum valves, are a type of safety valve. They are devices used to protect pressure vessels or piping systems. PV valves 204-206 typically consist of a pressure relief valve and a vacuum valve. When the internal pressure or vacuum level of the vessel exceeds a set value, the valve automatically opens, releasing some of the pressure or vacuum. Specifically, the PV valves are configured to operate within an absolute pressure range of 0.093 MPa to 0.12 MPa. When the cabin pressure exceeds 0.12 MPa, the pressure relief valve opens, releasing the cabin pressure from the cabin to the outside through a vent mast. When the cabin pressure falls below 0.093 MPa, a negative vacuum state is reached, and the vacuum valve opens, drawing air from the outside vent mast into the cabin, thereby preventing damage to the fuel tank and leaks caused by overpressure.

[0052] In some embodiments, the at least one fuel tank and the daily tank 106 are each provided with a pump, and are connected to the at least one fuel tank and the daily tank 106 via pipes 252, 254, 255, and 256; a pipe 257 is provided, and a three-way valve 225-226 is provided on the pipe 257, so that the sum of the fuel liquid volume and the sum of the top gas volume in the at least one fuel tank and the daily tank 106 remain unchanged through the opening and closing of the three-way valve 225-226 and the transfer of the pump, or through natural opening and closing by gravity, and the PV valves 204-206 do not need to be opened and closed. Figure 3As shown, pumps are defined as different names at different locations. A fuel pump is installed in at least one fuel tank, and a daily pump 203 is installed in the daily cabinet 106 . A pipeline 257 is provided, which maintains a horizontal connection through at least one fuel tank and a daily cabinet 106 and is located at the top of the tank. A three-way valve 225-226 is provided on the pipeline 257 near the fuel tank in the daily cabinet 106. The three-way valve 225-226 is Y-shaped and can open and close any two ports; a valve 212 and its pipeline for mutual opening and closing are provided at the bottom of the fuel tank; a control valve 223 and its pipeline are provided at the bottom of the daily cabinet 106 for discharging from the daily cabinet 106 to the fuel tank; when the fuel pump 201 transfers fuel to the daily cabinet 106, the three-way valve 225 is opened to keep the gas at the top of the tank circulating; when the fuel pump 202 transfers fuel to the daily cabinet 106, the three-way valve 226 is opened to keep the gas at the top of the tank circulating, and the volume of the fuel liquid in the fuel tank and the volume of the gas at the top remain unchanged, thereby, the PV valves 204-206 will not trigger suction and discharge.

[0053] In some embodiments, it also has a natural on-off function. When in use, when valve 212 or 223 is opened to allow the fluid between compartments or tanks to be naturally on and off by gravity, valves 225 and 226 are controlled to keep the gas at the top of at least one fuel tank and the daily cabinet 106 flowing between the two. Thus, there is no need to start the fuel pump and trigger the PV valves 204-206.

[0054] Furthermore, the at least one fuel tank and the daily cabinet 106 are respectively provided with at least one PV valve 204-206, and the at least one PV valve 204-206 has a common pipeline 253, one end of the common pipeline 253 is connected to the ventilation mast 273, and the other end is installed with the flow valve 224, the dry air pipe 271 and the one-way valve 232. A gas detector is provided between the at least one PV valve 204-206 and the ventilation mast 273 and is continuously monitored; nitrogen (not shown) enters through the dry air pipe 271, and is inerted and blown out of the pipeline 253 through the flow valve 224 and the one-way valve 232 in turn and discharged to the ventilation mast 273. When the gas detector 300 detects that the oxygen content is lower than 2% and the combustible gas content is lower than 20% LEL, the inerting stops. The gas source is then switched from nitrogen to dry air, which enters through dry air pipe 271. The dry air is regulated to a specified flow rate by flow valve 224. The dry air enters pipe 271, continuously ventilating pipeline 253 at a low rate, and is then discharged through vent mast 273. This ensures that if at least one of the PV valves 204-206 releases or leaks, the combustible gas within the tank is ventilated to gas detector 300 at a low rate, allowing gas detector 300 to detect the release or leak as soon as possible and issue an alarm if the combustible gas concentration exceeds 20% LEL. Common pipeline 253 is installed horizontally at the outlet of the three exemplary PV valves 204-206, and the gas detector is installed close to the PV valves 204-206.

[0055] Furthermore, the flow rate of the dry air output by the flow valve 224 after adjustment is set to a range of 0.5-2.8 m / s.

[0056] In this way, the dry air can help push the combustible gas to the gas detector position, so that any release or leakage of the three PV valves 204-206 can be detected as soon as possible.

[0057] The present invention also proposes an inerting monitoring method for a methanol filling system, which is used in the methanol filling system and inerting monitoring method of the above embodiment. Figure 4 As shown, the following steps are included:

[0058] Methanol filling system S1, which introduces nitrogen through nitrogen pipe 270 into at least one fuel tank, daily tank 106, evaporation gas pipe 251 and fuel filling pipe 252 for inerting, and the displaced gas is discharged through at least one filling station port or vent mast 273;

[0059] S2: Fuel is injected into at least one fuel tank or daily cabinet 106 through the fuel filling pipe 252 at any filling station. Nitrogen in the tank is discharged through the evaporation pipe 251 to a third-party receiving device or through the ventilation mast 273 by opening the control valve 217;

[0060] S3, after filling to the designated liquid level, the pipelines 251-252 are first purged through the nitrogen pipe 270 to blow the residual fuel in the pipelines to at least one fuel tank or daily cabinet 106, and then the control valves 210, 211, 219, 214, 215, 216, 218, 219, 222 are closed and the pipelines 251-252 are again purged with nitrogen for inerting. The process is stopped when the oxygen content is less than 2% and the combustible gas is less than 20% LEL as measured by a portable detector (not shown), and the control valves 217, 207, 208, 220, 221 are kept closed.

[0061] S4, dry air enters from the dry air pipe 271 to continuously ventilate the pipeline 253 at a low speed, and is discharged through the ventilation mast 273. The gas detector 300 continuously monitors the pipeline 253.

[0062] The replaced gas can be air or methanol evaporated gas. The replaced air is required to have an oxygen content of less than 2% and a combustible gas content of less than 20% LEL.

[0063] In addition, in the day tank 106, the day pump 203 delivers fuel via pipeline 272 to the fuel supply unit 290, which then delivers it to the main engine in the engine room. When a low-level alarm is triggered, the fuel pump 201 delivers fuel back to the day tank 106 via pipelines 254 and 252. During this process, valves 209 and 214 remain open. Alternatively, the fuel pump 202 can be activated to deliver fuel to the day tank 106 via pipelines 255 and 252. During this step, valves 218 and 214 remain open. During this process, the corresponding three-way valve 225 or 226 is synchronously controlled to open and close the gas flow between the tanks and cabinets, preventing the PV valves 204 and 206 from opening and closing.

[0064] This prevents the natural air inside the at least one fuel tank and the daily cabinet 106 from forming an explosive mixture with the fuel vapor. 100% LEL refers to the lower explosion limit (LEL) of a gas. This means that when a gas reaches this concentration, it could potentially explode if exposed to an ignition source. Therefore, 20% LEL means the gas concentration in air is 20% of the lower explosion limit. Therefore, if the gas concentration exceeds this value, necessary safety measures must be taken to prevent explosions.

[0065] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0066] 1. The present invention provides a methanol filling system. Through the technical solution of the present invention, the structure of the entire ship from the outer shell to the middle of the ship is composed of ballast tanks, isolation tanks, fuel tanks and daily cabinets in sequence. The top of the ship is kept horizontally arranged with the main deck, and the part below the main deck forms a U-shaped enclosure structure. The U-shaped enclosure structure constitutes multiple fuel leakage protections, which controls the leakage within the designated area, avoids the fuel from threatening other safe areas of the ship, and further improves the safety of the ship. In addition, an isolation control valve is provided between the fuel filling pipe and the methanol fuel tank to ensure that it is opened during filling and closed during non-operation. The filling station is equipped with an inert gas purge to ensure the safety of filling. The fuel tank and daily cabinet are arranged under the main deck to minimize the space they occupy on the main deck and facilitate the loading of cargo. When the fuel tank and daily cabinet are filled or transferred to each other, gas circulation can be achieved through the tank top connecting valve, thereby avoiding the waste of nitrogen and saving costs. In addition, the fuel liquid can be circulated through the tank bottom connecting valve instead of the pump for transfer, which is flexible.

[0067] 2. The present invention provides an inerting monitoring method, in which a gas detector is provided on the PV valve outlet pipeline. The pipeline is first inerted with gas. After the combustible gas content is detected to be lower than 20% LEL, slow dry air is used to maintain continuous ventilation of the PV valve outlet pipeline to the ventilation mast. When the content exceeds 20% LEL, an alarm is triggered.

[0068] In the several embodiments provided by the present invention, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are merely illustrative. For example, the division of the units can be a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, and can be electrical or other forms.

[0069] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0070] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0071] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A methanol filling system for providing a power source for a ship (100), comprising a ship (100) and its hull (101), a ballast tank (105), at least one fuel tank, an isolation void tank (104) and a service tank (106); characterized in that: The ballast tank (105), the cofferdam (104), the at least one fuel tank and the service tank (106) are arranged in sequence from the outer shell (101) to the middle of the ship, and the portions of the ballast tank (105), the cofferdam (104), the at least one fuel tank and the service tank (106) below the main deck form an enclosed structure with the main deck, so that after at least one of the service tank (106), the at least one fuel tank and the cofferdam (104) where fuel is stored is damaged, the ballast tank (105) can finally be used to form a leakage protection for the fuel; The methanol filling system is further provided with a fourth pipeline (257), the fourth pipeline (257) being maintained horizontally to pass through the at least one fuel tank and the daily cabinet (106), and being located at the top of the tank; a three-way valve (225-226) is provided on the fourth pipeline (257) in the daily cabinet (106) near the at least one fuel tank, the three-way valve (225-226) being Y-shaped and capable of opening and closing any two ports; a valve (212) and a pipeline for mutual opening and closing are provided at the bottom of the at least one fuel tank; a control valve (223) and a pipeline are provided at the bottom of the daily cabinet (106), for discharging from the daily cabinet (106) to the at least one fuel tank.

2. A methanol filling system according to claim 1, characterized in that: The invention also includes at least one filling station, wherein the at least one filling station includes an evaporation gas pipe (251), a fuel filling pipe (252), a nitrogen pipe (270), an isolation control valve (207, 208, 209, 210, 211, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222) and a filter (274) connected to each other.

3. A methanol filling system according to claim 2, characterized in that: The evaporation gas pipe (251) and the fuel filling pipe (252) are both provided with nitrogen pipes, so that the interior of the evaporation gas pipe (251) and the fuel filling pipe (252) are inerted and the oxygen content is reduced to less than 2% and the combustible gas is less than 20% LEL.

4. A methanol filling system according to claim 2, characterized in that: The at least one fuel tank and the daily service tank (106) are both provided with a nitrogen pipe (270) to inert the interior of the at least one fuel tank and the daily service tank (106) and reduce the oxygen content to less than 2% and the combustible gas to less than 20% LEL.

5. A methanol filling system according to claim 1, characterized in that: The at least one fuel tank and the daily cabinet (106) are respectively equipped with at least one PV valve (204-206), and the at least one PV valve (204-206) can automatically open or close according to the pressure difference between the at least one fuel tank, the isolation tank (104) and the ballast tank (105) and the outside of the tank, so as to keep the pressure in the cabin stable within a specified range; when performing a fuel filling operation, when the pressure in the cabin exceeds the specified range, the at least one PV valve (204-206) is opened to restore the pressure in the cabin to the specified range.

6. A methanol filling system according to claim 5, characterized in that: The at least one fuel tank and the daily service tank (106) are respectively provided with pumps, and are connected to the at least one fuel tank and the daily service tank (106) through a fuel filling pipe (252), a first pipeline (254), a second pipeline (255), and a third pipeline (256); by opening and closing the three-way valve (225-226) and transferring the pump, or by natural opening and closing due to gravity, the sum of the fuel liquid volume and the sum of the top gas volume in the at least one fuel tank and the daily service tank (106) are respectively kept unchanged, and the PV valves (204-206) do not need to be opened or closed.

7. A methanol filling system according to claim 6, characterized in that: The PV valves (204-206) have a common pipeline (253) and are installed horizontally; one end of the common pipeline (253) is connected to the ventilation mast (273), and the other end is installed with a flow valve (224), a dry air pipe (271) and a one-way valve (232); a gas detector (300) is provided between the at least one PV valve (204-206) and the ventilation mast (273) and is continuously monitored; nitrogen enters through the dry air pipe (271), passes through the flow valve (224) and the one-way valve (232) in sequence, inertizes and blows the common pipeline (253) and discharges it to the ventilation mast (273); when the gas detector (300) detects that the oxygen content is After the amount of gas is less than 2% and the combustible gas content is less than 20% LEL, inerting is stopped, and then the gas source is switched from nitrogen to dry air and enters from the dry air pipe (271), and the dry gas is adjusted to a specified flow rate through the flow valve (224), and enters from the dry air pipe (271) to continuously maintain micro-speed ventilation of the common pipeline (253), and is discharged through the ventilation mast (273), so that when at least one PV valve (204-206) releases or leaks, the combustible gas in the tank is blown to the gas detector (300) by micro-speed ventilation, so that the gas detector (300) detects the release or leakage of combustible gas as early as possible, and issues an alarm when the combustible gas concentration is detected to be higher than 20% LEL.

8. A methanol filling system according to claim 7, characterized in that: The flow rate of the dry air output after adjustment by the flow valve (224) is set within a range of 0.5-2.8 m / s.

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