Marine methanol fuel waste alcohol classification purification recycling system and method

Abstract

The application discloses a kind of waste methanol fuel alcohol classification purification recycling system and method for ship, including dirty alcohol cabin, for collecting and storing heavy pollution waste alcohol from liquid collecting pan and double-wall pipe;Mildly contaminated waste alcohol collection unit is used to collect mildly contaminated waste alcohol from pump, heat exchanger;Buffer tank is communicated with the mildly contaminated waste alcohol collection unit, for receiving and temporarily storing mildly contaminated waste alcohol, liquid level sensor is arranged in it;Multi-stage purification unit, its import is connected with the buffer tank by conveying pump, the multi-stage purification unit includes magnetic filter, multi-stage particle filter, coalescence dehydrator and adsorption acid remover in turn;Detection recycling unit is used for quality detection to purified methanol and according to detection result, it is sent back main fuel cabin or re-purification or sent to dirty alcohol cabin;Inert gas protection system and safety detection system.The application realizes the classification collection, efficient purification and recycling of waste methanol, improves fuel utilization, reduces operating cost and environmental pollution risk.

Description

Technical Field

[0001] This invention relates to the field of marine environmental protection technology and new energy applications, and in particular to a system and method for the classified collection, purification and reuse of waste methanol from marine methanol fuel. Background Technology

[0002] With increasingly stringent requirements from the International Maritime Organization (IMO) for ship emissions, methanol, as a clean and low-carbon alternative marine fuel, is being used more and more widely. However, in methanol fuel supply systems, waste methanol contaminated with water, lubricating oil, metal particles, acidic substances, etc., is inevitably generated from the collection pan, double-walled pipes, pumps, heat exchangers, etc. Traditional waste methanol treatment methods typically involve collecting all waste methanol on board, regardless of its contamination level, and then storing it until the ship docks, where it is then centrally processed by shore-based facilities. This "centralized collection, unified storage, shore-based processing" model has the following shortcomings: Cost issues: Shore-based treatment of waste methanol not only increases the cost of ship operation, but also places an additional burden on shore-based treatment facilities, especially on large ships with high methanol demand, where this cost is particularly significant.

[0003] Safety hazards: Waste methanol is considered hazardous waste, and there are high safety risks during its storage on ships and its transfer on shore. In particular, in closed storage tanks, flammable methanol vapor mixed with air may form an explosive atmosphere, posing a threat to the ship and its personnel.

[0004] Environmental risks: Improper disposal of waste methanol may cause marine pollution, especially when waste methanol containing heavy metals, oils and other harmful substances is discharged into the sea without proper treatment, the impact on the ecological environment is not to be ignored.

[0005] Resource waste: Slightly polluted waste methanol often contains a high level of methanol. Direct disposal or shore-based treatment without reuse means that a large amount of potentially usable methanol resources are wasted, failing to achieve efficient recycling of resources, which is inconsistent with the development concept of green shipping.

[0006] Therefore, there is an urgent need for a technology and system that can efficiently, safely, and automatically process and reuse waste methanol on board ships, so as to achieve closed-loop management of methanol fuel, reduce operating costs, and improve environmental benefits. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a system and method for classifying, purifying and reusing waste methanol fuel for marine use. This method enables the classification, collection and treatment of waste methanol with different levels of pollution, and the efficient purification of reusable, slightly polluted waste methanol before its return to the fuel system.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a system for classifying, purifying, and reusing waste methanol from marine methanol fuel, the system being installed on a methanol-fueled vessel, comprising: A sorting and collection unit is used to collect and store waste liquids with different pollutant concentrations from different parts of the ship. The sorting and collection unit includes at least one waste methanol tank and at least one buffer tank. The waste methanol tank is used to collect heavily polluted waste methanol from the collection pan and double-walled pipe, and the buffer tank is used to collect lightly polluted waste methanol from equipment such as pumps and heat exchangers, so as to achieve source sorting and collection of waste methanol.

[0009] The multi-stage purification unit includes multiple continuously operating purification modules that perform solid-liquid separation, dehydration, and impurity removal on the lightly contaminated waste liquid from the sorting and collection unit.

[0010] The quality inspection and reuse unit has its inlet connected to the outlet of the multi-stage purification unit. It is used to inspect the quality of the purified methanol and control the directional flow of the waste methanol according to the inspection results, so that it flows back to the main storage device and re-enters the purification unit, or is transferred to the waste methanol tank.

[0011] The inert gas covering unit maintains a low-oxygen environment inside the buffer tank and the waste alcohol chamber by filling the top space with inert gas, thus ensuring the safety of the processing.

[0012] The safety detection system includes methanol concentration, temperature, and pressure sensors, which are used to monitor the system's safety status in real time, automatically control the operation of the device, and trigger alarms in abnormal situations.

[0013] The integrated controller is configured to perform process control and safety monitoring functions.

[0014] Furthermore, the multi-stage purification unit includes, in sequence along the fluid direction, a magnetic filter, a multi-stage particle filter, a coalescing dehydrator, and an adsorption deacidifier.

[0015] Furthermore, the quality testing and reuse unit includes an online methanol quality analyzer and a valve; the first outlet of the valve is connected to the ship's main fuel tank via a pipeline, the second outlet is connected to the inlet of the buffer tank via a pipeline, and the third outlet is connected to the waste methanol tank via a pipeline.

[0016] Furthermore, the safety detection system includes: a methanol concentration sensor, distributed within the enclosed area where the buffer tank, waste methanol chamber, multi-stage purification unit, and pipeline valve group are located; a temperature sensor, installed inside the buffer tank and waste methanol chamber; a pressure sensor, installed on the top of the buffer tank and waste methanol chamber; and an alarm unit, used to issue audible and visual alarm signals when parameters are abnormal.

[0017] Furthermore, the integrated controller is configured to perform process control and safety monitoring functions, including: When the received liquid level signal reaches the preset high liquid level value, the delivery pump is started; Receive signals from the online methanol quality analyzer and control the opening and closing of the valve; It continuously reads methanol concentration, temperature, and pressure data, and triggers the alarm unit to issue a corresponding alarm signal and perform a safety interlock shutdown operation when the detected value exceeds the preset alarm value.

[0018] Secondly, the present invention provides a method for classifying, purifying, and reusing waste methanol from marine methanol fuel using the above-mentioned system, comprising the following steps: S1: Categorized collection: Heavily contaminated waste alcohol from the collection pan and double-walled pipe is directly transported to the waste alcohol tank for storage; lightly contaminated waste alcohol from the pump and heat exchanger is transported to the buffer tank for temporary storage.

[0019] S2: Trigger purification: The liquid level in the buffer tank is monitored in real time by the first liquid level sensor in the buffer tank. When the liquid level reaches the preset value, the transfer pump is started to pump the slightly contaminated waste alcohol in the buffer tank into the multi-stage purification unit.

[0020] S3: Multi-stage purification: Waste methanol flows sequentially through a magnetic filter in a multi-stage purification unit to adsorb and remove magnetic impurities, through a multi-stage particle filter to remove solid particles, through a coalescing dehydrator to coalesce and separate free water, and through an adsorption deacidifier to adsorb and remove acidic substances, thus obtaining purified methanol.

[0021] S4: Detection and Reuse: Real-time detection of purified methanol is performed using an online methanol quality analyzer; If the test results meet the methanol standard for the main fuel tank, the control valve will connect to the pipeline to the main fuel tank to deliver the purified methanol to the main fuel tank.

[0022] If the test indicators fail to meet the standards, the control valve will connect the pipeline to the buffer tank, and the purified methanol will be returned to the buffer tank for re-purification.

[0023] If the test indicators still fail to meet the standards after multiple cycles of purification, the control valve will be connected to the pipeline to the waste methanol tank, and the unqualified methanol will be discharged into the waste methanol tank.

[0024] During the execution of steps S1-S5 above, real-time safety monitoring and interlocking protection are performed, including: Continuously read methanol concentration, temperature, and pressure data; When the value detected by any methanol concentration sensor exceeds the preset low alarm value, the alarm unit is triggered to issue a pre-alarm signal to prompt personnel to check. When any methanol concentration sensor detects a value exceeding the preset high alarm value, or any temperature sensor detects a value exceeding the limit, or a pressure sensor detects an abnormal pressure, a high-level audible and visual alarm will be immediately activated, and one or a combination of the following safety interlock actions will be executed simultaneously: Emergency stop of the delivery pump operation; Close the emergency shut-off valves on the relevant pipelines; Increase the purging flow rate of the inert gas protection system to force the replacement of the hazardous environment.

[0025] The advantages of this invention are as follows: 1. Cost Savings: This invention separates lightly and moderately polluted waste methanol from heavily polluted waste methanol at the source. Lightly polluted waste methanol is treated and reused on board in real time, reducing ship operating costs and alleviating the burden on shore-based treatment facilities. Furthermore, the automated cleaning and maintenance design reduces the need for manual intervention, lowers maintenance costs, and ensures long-term stable operation of the system.

[0026] 2. Avoiding Safety Hazards: Light to moderate contaminants are classified, treated, and recycled on board, avoiding safety risks during onboard storage and shore transfer. The use of inert gas covering technology not only enhances system safety but also optimizes storage conditions and extends the shelf life of methanol. Integrated safety monitoring and interlocking protection mechanisms effectively prevent potential risks, reduce the likelihood of accidents, and provide a solid guarantee for ship safety.

[0027] 3. Reduced resource waste: By combining source-level classified collection with multi-stage purification technology, this system greatly improves the efficiency and quality of methanol recovery, achieving efficient resource recycling and aligning with the development concept of green shipping. It also reduces energy waste and lowers operating costs.

[0028] 4. Ensure recycling quality: By implementing an online detection and control mechanism, it can respond to changes in waste liquid quality in real time, ensuring that the recycled methanol meets high standards and avoiding reprocessing or waste due to substandard quality.

[0029] It is evident that this invention provides a more efficient, safer, and more environmentally friendly waste methanol classification, purification, and reuse system and method, which realizes the classification, collection, treatment, detection, and reuse of waste methanol, improves the utilization rate of methanol fuel, reduces operating costs, reduces the risk of environmental pollution, and ensures the safety of system operation. Attached Figure Description

[0030] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the process flow for the classification, purification, and reuse system of waste methanol fuel for marine use.

[0031] Figure 2 Schematic diagram of a multi-stage purification unit.

[0032] In the diagram: 1. Dirty alcohol tank; 2. Buffer tank; 21. First liquid level sensor; 3. Multi-stage purification unit; 31. Magnetic filter; 32. Multi-stage particulate filter; 33. Coalescing dehydrator; 34. Adsorption deacidifier; 4. Transfer pump; 51. Online methanol quality analyzer; 52. Valve; 6. Main fuel tank; 7. Inert gas protection system; 81. Methanol concentration sensor; Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0034] This invention provides a system for classifying, purifying, and reusing waste methanol from marine methanol fuel, such as... Figure 1 As shown, the system mainly includes a waste alcohol tank 1, a buffer tank 2, a multi-stage purification unit 3, a transfer pump 4, a detection and reuse unit 5, an inert gas protection system 7, a safety detection system, and an integrated controller.

[0035] In one embodiment of the invention, the waste alcohol tank 1 receives heavily contaminated waste alcohol from the ship's fuel system collection pan and double-walled pipes via pipelines. The buffer tank 2 is used to temporarily store lightly contaminated waste alcohol from the methanol pump, heat exchanger, etc., and is equipped with a first level sensor 21 to monitor the tank's internal condition. The outlet of the buffer tank 2 is connected to the inlet of the multi-stage purification unit 3 via a transfer pump 4.

[0036] In this embodiment, the rational arrangement of the waste methanol tank 1 and the buffer tank 2 enables source-based classified collection of methanol waste liquid with different levels of contamination. The waste methanol tank 1 is specifically designed to receive heavily contaminated waste methanol from high-risk leak points such as the collection pan and double-walled pipes. This waste liquid often contains large amounts of water, oil, metal particles, and other impurities that are difficult to reuse directly. The buffer tank 2, on the other hand, is used to collect lightly contaminated waste methanol generated during the normal operation of equipment such as pumps and heat exchangers (e.g., minor leaks in seals, maintenance drainage, or fluctuations in operating conditions). This type of waste liquid mainly carries trace amounts of lubricating oil, wear particles, or water due to contact with internal equipment components. Its characteristics include low contaminant concentration and relatively simple composition. Therefore, it does not require complex deep treatment; simple purification processes (such as filtration and dehydration) are sufficient to effectively remove impurities and restore sufficient fuel quality, resulting in significant economic reuse value. This classified collection method not only simplifies the complexity of subsequent purification processes but also improves purification efficiency and resource recycling rates. It ensures that only lightly polluted waste methanol enters the multi-stage purification unit 3 for treatment, while heavily polluted waste liquid is directly stored in the waste methanol tank 1 for onshore professional treatment. This reduces the burden and potential damage to the multi-stage purification unit 3, avoiding resource waste and environmental pollution. Through precise classification at the source, the system can maximize the quality of purified methanol, enabling its successful reuse in the main fuel tank 6. Furthermore, different treatment strategies are adopted for waste methanol with varying degrees of pollution, effectively improving the overall system's operational economy and safety.

[0037] Furthermore, the buffer tank 2 not only collects lightly contaminated waste liquid, but its first liquid level sensor 21 can also monitor liquid level changes in real time and promptly initiate the purification process. This combination of the sorting and collection unit and the purification unit ensures that lightly contaminated waste methanol is promptly purified and reused, while heavily contaminated waste methanol is safely stored, preventing pollution of the main fuel system, improving the overall utilization rate of methanol fuel, and reducing ship operating costs and environmental pollution risks. It is evident that the methanol sorting, purification, and reuse strategy of this invention achieves refined resource management and improves the environmental performance and economic benefits of ships.

[0038] The multi-stage purification unit 3 is the core of the system. In one embodiment of the present invention, see [link to embodiment 3]. Figure 2The system comprises multiple purification modules, sequentially arranged along the fluid direction, including a magnetic filter 31, a multi-stage particulate filter 32, a coalescing dehydrator 33, and an adsorption deacidifier 34. The magnetic filter 31 contains a powerful magnetic rod or magnetic grid to adsorb and remove ferromagnetic particles generated by wear in waste methanol. The multi-stage particulate filter 32 uses coarse and fine filter elements connected in series to remove solid impurities of different particle sizes, retaining non-ferromagnetic solid particles, colloids, and other mechanical impurities. The coalescing dehydrator 33 contains a coalescing filter element that agglomerates and enlarges tiny water droplets in waste methanol, which are then separated by gravity settling, effectively removing moisture. The adsorption deacidifier 34 is filled with alkaline adsorbents such as activated alumina or molecular sieves (e.g., specialized ion exchange resins or molecular sieves) to neutralize and adsorb acidic substances such as formic acid and other trace organic impurities that may be present in methanol.

[0039] In this embodiment, the multi-stage purification unit 3, composed of a magnetic filter 31, a multi-stage particulate filter 32, a coalescing dehydrator 33, and an adsorption deacidifier 34, can efficiently remove various pollutants from lightly contaminated waste methanol in a targeted, step-by-step manner, ultimately producing methanol that meets the standards for use in the main fuel tank 6. This integrated and modular purification unit has a compact structure and a simple process, eliminating the need for large distillation towers, centrifuges, or complex chemical regeneration devices required by onshore treatment systems, thus significantly reducing equipment footprint, initial investment, and operating and maintenance costs. Furthermore, the system adapts to the limited space and fluctuating operating conditions of ships, enabling online, continuous purification and immediate reuse of waste methanol during navigation, effectively improving the overall utilization efficiency of methanol fuel and the economics of ship operation, demonstrating significant practicality and innovative advantages. In one embodiment of the invention, the detection and reuse unit includes an online methanol quality analyzer 51 and a valve 52. The online analyzer 51 can detect key indicators such as the purity, moisture content, and acid value of the purified methanol in real time. The first outlet of valve 52 is connected to the main fuel tank 6 of the ship via a pipeline, the second outlet is connected to the inlet of the buffer tank 2 via a pipeline, and the third outlet is connected to the waste alcohol tank (1) via a pipeline.

[0040] In this embodiment, the detection and reuse unit performs real-time detection on the quality of the purified methanol to ensure that only methanol that meets the quality standards can be sent back to the main fuel tank 6. Methanol that does not meet the standards will be returned to the buffer tank 2 for further purification or directly discharged into the waste methanol tank 1. This effectively avoids damage to the fuel system caused by low-quality methanol and ensures the normal operation of the ship's engine.

[0041] In one embodiment of the present invention, the inert gas protection system 7 is connected to the top space of the buffer tank 2 and the methanol contaminated tank 1 via pipelines, continuously filling it with inert gases such as nitrogen to maintain a slightly positive pressure and inert environment inside the tank, preventing methanol vapor from forming an explosive mixture with air. The inert gas protection system 7 provides safety assurance for the processing, and the safety detection system, in conjunction with the integrated controller, performs full-process monitoring and anomaly warnings, ensuring the safety and stability of system operation, reducing operating costs, and minimizing environmental pollution risks, embodying the concept of green shipping.

[0042] In one embodiment of the invention, the safety detection system includes multiple methanol concentration sensors 81, distributed around the buffer tank 2, the waste methanol chamber 1, and at the top and bottom of the chamber containing the pumps and filter group (because methanol vapor density is higher than air). Temperature and pressure sensor probes are inserted into the liquid and gas phase spaces of the buffer tank 2 and the waste methanol chamber 1, respectively. All these sensors are connected to an integrated controller.

[0043] In one embodiment of the present invention, the integrated controller employs a PLC, which receives signals from various sensors and controls the actions of the delivery pump 4, valve 51, inert gas protection system 7, and alarm unit, thereby achieving integrated management of the system's automatic operation and safety monitoring. The integrated controller has preset process control logic and safety interlock values, such as: a low methanol concentration alarm value of 25 ppm and a high alarm value of 50 ppm; a high temperature alarm value of 40°C; and abnormal pressure fluctuation ranges. When abnormal parameters are detected, the integrated controller triggers the alarm unit to issue a corresponding alarm signal and executes corresponding safety interlock actions, such as stopping the delivery pump 4, closing the emergency shut-off valve, and increasing the inert gas supply.

[0044] Specifically, the integrated controller is configured to perform process control and safety monitoring functions, including: When the received liquid level signal reaches the preset high liquid level value, the delivery pump 4 is started; Receive signals from the online methanol quality analyzer 51 and control the opening and closing of the valve 52; It continuously reads methanol concentration, temperature, and pressure data, and triggers the alarm unit to issue a corresponding alarm signal and perform a safety interlock shutdown operation when the detected value exceeds the preset alarm value.

[0045] The integrated controller monitors safety data in real time. If any abnormality is detected, such as an abnormally high methanol concentration or deviations in temperature or pressure parameters from the normal range, an emergency response mechanism will be immediately activated. This includes automatically closing valves to cut off material flow and increasing the supply of inert gas to dilute the methanol vapor concentration, effectively preventing accidents and ensuring the safety of operators and the vessel. This intelligent safety monitoring and interlocking protection significantly enhances the system's ability to respond to emergencies, reduces potential safety risks, and ensures the continuous and stable operation of the classification, purification, and reuse process.

[0046] Furthermore, in one embodiment of the present invention, a method for classifying, purifying, and reusing waste methanol from marine methanol fuel is also provided, comprising the following steps: S1: Classified collection: Heavily contaminated waste alcohol from the collection pan and double-walled pipe is directly transported to the waste alcohol tank 1 for storage; lightly contaminated waste alcohol from the pump and heat exchanger is transported to the buffer tank 2 for temporary storage.

[0047] S2: Triggered Purification: Slightly contaminated waste alcohol accumulates in buffer tank 2. When the first liquid level sensor 21 detects that the liquid level has reached the set high level, it sends a signal to the integrated controller. The integrated controller starts the transfer pump 4 to pump the waste alcohol into the multi-stage purification unit 3.

[0048] S3: Multi-stage purification: Waste methanol flows sequentially through the magnetic filter 31 of the multi-stage purification unit 3 to adsorb and remove magnetic impurities, through the multi-stage particle filter 32 to filter out solid particles, through the coalescing dehydrator 33 to coalesce and separate free water, and through the adsorption deacidifier 34 to adsorb and remove acidic substances, thus obtaining purified methanol.

[0049] S4: Detection and Reuse The purified methanol was detected in real time using an online methanol quality analyzer 51. If the test indicators meet the methanol standard for the main fuel tank 6, then control valve 52 is connected to the pipeline to the main fuel tank (6) to transport the purified methanol to the main fuel tank 6; If the test indicators fail to meet the standards, control valve 52 will connect to the pipeline to buffer tank 2, and the purified methanol will be returned to buffer tank 2 for re-purification. If the test indicators still fail to meet the standards after multiple cycles (e.g., 3 times) of purification, control valve 52 will connect to the pipeline to waste methanol tank 1, and the unqualified methanol will be discharged into waste methanol tank 1.

[0050] During the execution of steps S1-S5 above, real-time safety monitoring and interlocking protection are performed, including: Continuously read methanol concentration, temperature, and pressure data; When the value detected by any methanol concentration sensor 81 exceeds the preset low alarm value, the alarm unit is triggered to issue a pre-alarm signal to prompt personnel to check. When any methanol concentration sensor 81 detects a value exceeding the preset high alarm value, or any temperature sensor detects a value exceeding the limit, or a pressure sensor detects an abnormal pressure, a high-level audible and visual alarm will be immediately activated, and one or a combination of the following safety interlock actions will be executed simultaneously: Emergency stop of delivery pump 4; Close the emergency shut-off valves on the relevant pipelines; Increase the purging flow rate of the inert gas protection system 7 to force the replacement of the hazardous environment.

[0051] In one embodiment of the present invention, the method further includes daily automatic cleaning and periodic manual maintenance of the multi-stage purification unit 3; The daily automatic cleaning includes: after performing a set number of purification operations, using pure methanol to automatically backwash and purge the multi-stage purification unit 3 and its connecting pipelines; The periodic manual maintenance includes: periodically checking, replacing or regenerating the filter elements, coalescing filter elements and adsorbents in the multi-stage purification unit 3, and performing daily automatic cleaning and periodic manual maintenance on the multi-stage purification unit 3. The daily automatic cleaning includes: after performing a set number of purification operations, using pure methanol to automatically backwash and purge the multi-stage purification unit 3 and its connecting pipelines; The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A system for classifying, purifying, and reusing waste methanol from marine methanol fuel, characterized in that, The system is installed on methanol-fueled ships and includes: a sorting and collection unit for collecting and storing waste liquids with different pollutant concentrations from different parts of the ship; the sorting and collection unit includes at least one waste methanol tank and at least one buffer tank, the waste methanol tank for collecting heavily polluted waste methanol from the collection pan and double-walled pipe, and the buffer tank for collecting lightly polluted waste methanol from equipment such as pumps and heat exchangers, thereby achieving source-based sorting and collection of waste methanol; The multi-stage purification unit (3) includes multiple continuously operating purification modules for solid-liquid separation, dehydration and impurity removal of lightly polluted waste liquid from the classification and collection unit; The quality testing and reuse unit is connected to the multi-stage purification unit (3) and is used to test the quality of the purified methanol and control the directional flow of the waste methanol according to the test results, so that it flows back to the main storage device and re-enters the multi-stage purification unit, or is transferred to the waste methanol tank. An inert gas covering unit maintains a low-oxygen environment inside the buffer tank (2) and the waste alcohol chamber (1) by filling the top space with inert gas, thus ensuring the safety of the processing. The safety detection system includes methanol concentration, temperature, and pressure sensors, which are used to monitor the system's safety status in real time, automatically control the operation of the device, and trigger alarms in abnormal situations. The integrated controller is configured to perform process control and safety monitoring functions.

2. The marine methanol fuel waste alcohol classification, purification and reuse system according to claim 1, characterized in that: The multi-stage purification unit (3) includes, in sequence along the fluid direction: Magnetic filter (31) is used to adsorb and remove iron-containing magnetic impurities from waste alcohol; A multi-stage particulate filter (32) is used to filter out solid particulate contaminants from waste alcohol; Coagulation dehydrator (33) is used to coalesce and separate trace amounts of free water from waste alcohol; The adsorption deacidifier (34) is filled with alkaline adsorbent and is used to adsorb and remove acidic substances from waste alcohol.

3. The marine methanol fuel waste alcohol classification, purification and reuse system according to claim 1, characterized in that: The quality testing and reuse unit includes an online methanol quality analyzer (51) and valves (52); the three outlets of the valve (52) are respectively connected to the main fuel tank (6), the inlet of the buffer tank (2) and the waste methanol tank (1).

4. The marine methanol fuel waste alcohol classification, purification and reuse system according to claim 1, characterized in that: The safety detection system includes a methanol concentration sensor (81), which is distributed in the enclosed area where the buffer tank (2), the waste methanol chamber (1), the multi-stage purification unit (3) and the pipeline valve group are located, and is used to monitor the methanol vapor concentration in the ambient atmosphere in real time. Temperature sensors are installed inside the buffer tank (2) and the methanol tank (1) to monitor the temperature of the methanol liquid; Pressure sensors are installed on the top of the buffer tank (2) and the sludge chamber (1) to monitor their internal pressure; An alarm unit is used to issue audible and visual alarm signals when parameters are abnormal.

5. The marine methanol fuel waste alcohol classification, purification and reuse system according to claim 1, characterized in that: The integrated controller is electrically connected to the first liquid level sensor (21), the delivery pump (4), the online methanol quality analyzer (51), the valve (52), the inert gas protection system (7), the safety detection system, and the alarm unit.

6. The marine methanol fuel waste alcohol classification, purification and reuse system according to claim 5, characterized in that: The integrated controller is configured to perform process control and safety monitoring functions, including: when the received liquid level signal reaches a preset high liquid level value, starting the transfer pump (4). Receive signals from the online methanol quality analyzer (51) and control the opening and closing of the valve (52); It continuously reads methanol concentration, temperature, and pressure data, and triggers the alarm unit to issue a corresponding alarm signal and perform a safety interlock shutdown operation when the detected value exceeds the preset alarm value.

7. The marine methanol fuel waste alcohol classification, purification and reuse system according to claim 1, characterized in that: The buffer tank (2) is equipped with a first liquid level sensor (21) for monitoring the liquid level, and has high and low liquid level alarm functions.

8. A method for classifying, purifying, and reusing waste methanol from marine methanol fuel using the system described in any one of claims 1-7, characterized in that, Includes the following steps: S1: Classified collection: Heavy-polluted waste alcohol from the collection pan and double-walled pipe is directly transported to the waste alcohol tank (1) for storage; light-polluted waste alcohol from the pump and heat exchanger is transported to the buffer tank (2) for temporary storage; S2: Trigger purification: The liquid level in the buffer tank (2) is monitored in real time by the first liquid level sensor (21) in the buffer tank (2). When the liquid level reaches the preset value, the transfer pump (4) is started to pump the slightly polluted waste alcohol in the buffer tank (2) into the multi-stage purification unit (3). S3: Multi-stage purification: Waste methanol flows sequentially through the magnetic filter (31) of the multi-stage purification unit (3) to adsorb and remove magnetic impurities, through the multi-stage particle filter (32) to remove solid particles, through the coalescing dehydrator (33) to coalesce and separate free water, and through the adsorption deacidifier (34) to adsorb and remove acidic substances, thus obtaining purified methanol. S4: Detection and Reuse: The purified methanol is detected in real time using an online methanol quality analyzer (51). If the detection index meets the methanol standard for the main fuel tank (6), the control valve (52) is connected to the pipeline of the main fuel tank (6) to transport the purified methanol to the main fuel tank (6). If the detection index does not meet the standard, the control valve (52) is connected to the pipeline of the buffer tank (2) to return the purified methanol to the buffer tank (2) for re-purification. If the detection index still fails to meet the standard after multiple cycles of purification, the control valve (52) is connected to the pipeline of the waste methanol tank (1) to discharge the unqualified methanol to the waste methanol tank (1). During the execution of steps S1-S5 above, real-time safety monitoring and interlock protection are performed, including: continuously reading methanol concentration, temperature, and pressure data; When the value detected by any methanol concentration sensor (81) exceeds the preset low alarm value, the alarm unit is triggered to issue a pre-alarm signal to prompt personnel to check; when the value detected by any methanol concentration sensor (81) exceeds the preset high alarm value, or the value detected by any temperature sensor exceeds the limit, or the pressure sensor detects an abnormal pressure, a high-level audible and visual alarm is immediately activated, and one or a combination of the following safety interlock actions are executed simultaneously: Emergency stop of the operation of the delivery pump (4); Close the emergency shut-off valves on the relevant pipelines; Increase the purging flow rate of the inert gas protection system (7) to force the replacement of the hazardous environment.

9. The method according to claim 8, characterized in that: During the storage and purification process in steps S1 and S2, inert gas is continuously supplied to the top space of the buffer tank (2) and the waste alcohol chamber (1) through the inert gas protection system (7) to maintain the slightly positive pressure inert environment inside.

10. The method according to claim 8 or 9, characterized in that: It also includes system maintenance: daily automatic cleaning and periodic manual maintenance of the multi-stage purification unit (3); the daily automatic cleaning includes: after performing a set number of purification operations, using pure methanol to automatically backwash and purge the multi-stage purification unit (3) and its connecting pipelines; the periodic manual maintenance includes: periodically checking, replacing or regenerating the filter element, coalescing filter element and adsorbent in the multi-stage purification unit (3).

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