Deep-sea plume in-situ particle size monitoring device and method based on multi-stage filter membrane differential pressure method

Abstract

The present application relates to the technical field of deep-sea mining environment monitoring, and provides a deep-sea plume in-situ particle size monitoring device and method based on a multi-stage filter membrane differential pressure method.The device comprises a main body bin, a suction pump and a seabed support frame.A steady flow chamber, a flowmeter, a multi-stage filter membrane sampling device, a differential pressure monitoring assembly, a data processing control unit and a battery bin are integrated in the main body bin.The sampling device is provided with a staged filter membrane assembly composed of filter membranes with pore diameters decreasing in the water flow direction from large to small, and the differential pressure monitoring assembly is configured in one-to-one correspondence with each stage of filter membrane.The method comprises the steps of indoor test preparation, reference pressure calibration, device deployment, plume water introduction into sampling, device recovery, data reading and calculation of particle mass proportion in different particle size intervals based on the pressure difference correction of each stage of filter membrane.The present application can realize in-situ continuous monitoring of multi-stage particle size distribution of deep-sea plume particles through active extraction of plume water, multi-stage staged filtration and in-situ differential pressure monitoring, does not depend on water transparency, is suitable for deep-sea high-pressure low-temperature high-turbidity environment, and provides reliable data support for deep-sea mining environmental impact assessment.

Description

Technical Field

[0001] This invention relates to the fields of deep-sea mining and environmental monitoring technology, and more specifically, to a deep-sea plume in-situ particle size monitoring device and method based on multi-stage filter membrane differential pressure method. Background Technology

[0002] With the rapid development of deep-sea mineral resource development, a large amount of suspended particulate matter is inevitably generated during deep-sea mining, forming plumes. These plume particles mainly include mineral particles (such as sand, mud, and clay), bioclastics, organic particles, and microbubbles, and their diffusion and sedimentation behavior in seawater has a potential impact on the seabed ecosystem and hydrodynamic characteristics. The particle size, composition, and concentration of these particulate plumes vary dynamically with water flow velocity, mining operation intensity, and topographic conditions. Therefore, accurate and real-time monitoring of the particle size distribution, composition ratio, concentration, and sedimentation characteristics of deep-sea plume particles is of great significance for environmental impact assessment, ecological risk analysis, and mining process optimization.

[0003] In existing technologies, the following methods are mainly used for measuring the particle size and monitoring particulate matter in deep-sea plumes: 1. Laser and optical particle size measurement: By using LISST and other series of instruments to pass a laser beam through a suspended plume of water sample, the angular distribution of scattered light is analyzed to calculate the particle size distribution, enabling in-situ continuous observation.

[0004] 2. Acoustic Doppler and water flow velocity observation instrument: By measuring changes in water flow velocity and echo intensity, the concentration and movement of suspended particles can be indirectly estimated, and the distribution of particles in the water can be calculated.

[0005] 3. In vitro sampling method: Water samples are collected using methods such as water sampling bottles, trawls, and filter membranes and returned to the laboratory for analysis to obtain the particle size distribution and total mass of mineral particles, organic particles, and biological debris in the plume.

[0006] 4. In-situ sediment capture sedimentator: used to capture samples of suspended particles settling, and to analyze sediment volume, particle size and particle composition.

[0007] However, the above methods have certain limitations: 1. Insufficient real-time performance: Ex vivo sampling and sediment trapping methods require sample recovery and analysis, and cannot obtain continuous, dynamic in-situ monitoring data.

[0008] 2. Poor environmental adaptability: Optical instruments such as LISST are sensitive to high concentrations of suspended particles, mixed mineral-organic particles, and strong current disturbances. The high pressure and low temperature environment in the deep sea can affect the performance of the instruments.

[0009] 3. Limited particle size resolution: Most in-situ instruments have difficulty accurately distinguishing between fine and coarse particles in high-concentration, multi-component mixed plumes, and cannot fully capture the multi-level particle size and composition information of the plume.

[0010] 4. In-situ high-precision instruments are large in size and consume a lot of power, requiring operation with ROV / AUV or a professional platform, which limits continuous long-term monitoring.

[0011] Therefore, there is an urgent need for a new technology solution that can achieve in-situ, multi-stage, and continuous sampling and particle size measurement in deep-sea environments. This solution should be able to simultaneously obtain the particle size distribution, particle mass, and composition ratio of plume particles, and be adaptable to high-pressure, low-temperature, and complex flow field environments, providing scientific and reliable data support for environmental impact assessment and ecological risk analysis in deep-sea mining. Summary of the Invention

[0012] To overcome the shortcomings of existing technologies, this invention provides an in-situ particle size monitoring device and method for deep-sea plumes based on multi-stage filter membrane differential pressure. This invention addresses the problems of insufficient real-time performance, limited particle size classification capabilities, poor adaptability to the high-pressure and low-temperature environment of the deep sea, and difficulty in achieving continuous in-situ monitoring in existing deep-sea mining plume particle monitoring methods. It provides an in-situ particle size monitoring device and method for deep-sea plumes based on pressure difference response and multi-stage filter membrane separation. This device can actively extract, stabilize, measure flow rate, perform graded filtration, and monitor differential pressure in plume water in a deep-sea in-situ environment. Furthermore, it can inversely determine the content of particles of different sizes in the plume based on pressure changes before and after different pore size filter membranes, thereby achieving in-situ, continuous, and multi-stage particle size monitoring of deep-sea mining plumes.

[0013] The present invention is achieved through the following technical solution: a deep-sea plume in-situ particle size monitoring device based on multi-stage filter membrane differential pressure method, comprising a main chamber, a suction pump and a seabed support frame, wherein the main chamber integrates and installs a flow stabilization chamber, a flow meter, a multi-stage filter membrane sampling device, a differential pressure monitoring component, a data processing control unit and a battery compartment; The main chamber has a water inlet at the front end, and the suction pump is connected to the water inlet; A flow stabilizing chamber is connected in series downstream of the suction pump, a flow meter is connected in series downstream of the flow stabilizing chamber, and a multi-stage filter membrane sampling device is connected in series downstream of the flow meter. The multi-stage filter membrane sampling device is composed of several stages of filter membranes with different pore sizes arranged sequentially along the water flow direction. The pore size of each stage of the filter membrane in the multi-stage filter membrane assembly decreases sequentially from large to small along the water flow direction. The differential pressure monitoring components are configured one-to-one with each stage of the filter membrane. The data processing and control unit is electrically connected to the flow meter and the differential pressure monitoring components. A discharge outlet is located at the end of the main compartment. The battery compartment is electrically connected to all electrical components within the main compartment. A battery interface is located at one end of the main compartment, and this interface is electrically connected to the charging terminal of the battery compartment.

[0014] As a preferred option, a base plate is fixedly installed at the bottom of the seabed support frame.

[0015] As a preferred option, a screen is installed on the inlet, and a protective cover is also provided on the outside of the inlet.

[0016] As a preferred embodiment, the multi-stage membrane sampling device is provided with an outlet at its end, which is connected to the discharge outlet. Further, each stage of the graded membrane assembly consists of replaceable single-piece membranes. The graded membrane assembly includes an upper crossbeam, a base, and a lower support base, a fixing ring, and a locking buckle, all equal in number to the number of single-piece membranes. The support ring is fixedly mounted on the base via the support base, and a single-piece membrane is placed inside the support ring. One side of the support ring is hinged to the fixing ring, and the locking buckle is located on the other side of the support ring, detachably locking the corresponding end of the fixing ring. Each stage of the filter membrane is also axially limited and fixed by filter membrane fixing buckles, and the base is fixedly installed on the inner wall of the flow channel of the multi-stage filter membrane sampling device.

[0017] Furthermore, the graded filter membrane assembly is provided with a total of 6 levels of single filter membranes, and the pore sizes of each level of filter membrane along the water flow direction are 75μm, 50μm, 25μm, 10μm, 5μm and 1μm respectively.

[0018] Furthermore, the differential pressure monitoring component includes a pressure system installed on each stage of the single-layer filter membrane. The pressure system includes a pre-pressure tap, a post-pressure tap, a pressure tapping hose, and a miniature differential pressure gauge. The pre-pressure tap is located on the upstream flow channel wall of the corresponding single-layer filter membrane, and the post-pressure tap is located on the downstream flow channel wall of the corresponding single-layer filter membrane. The pre-pressure tap and the post-pressure tap are respectively connected to the miniature differential pressure gauge through pressure tapping hoses. The signal output terminal of the miniature differential pressure gauge is connected to the data processing and control unit.

[0019] A method for in-situ particle size monitoring of deep-sea plumes based on multi-stage filter membrane differential pressure method specifically includes the following steps: Step S1: Preparation for indoor testing: Step S1-1: Filter membrane installation and equipment inspection: Before conducting in-situ plume particle size monitoring, indoor tests were first conducted to prepare the deep-sea plume in-situ particle size monitoring equipment. Single-layer filter membranes with different pore sizes were sequentially installed in the multi-stage filter membrane sampling device, and the pore size, installation position, and installation sequence of each stage of the single-layer filter membrane were confirmed. The single-layer filter membranes of each stage were arranged in descending order of pore size, so that after the plume water enters the multi-stage filter membrane sampling device, suspended particles larger than the corresponding filter membrane pore size can be intercepted stage by stage, while particles smaller than the corresponding filter membrane pore size are carried by the water flow to the next stage of filter membrane. After the filter membranes were installed, the connection relationship between the inlet, suction pump, flow stabilization chamber, flow meter, multi-stage filter membrane sampling device, discharge outlet, and data processing control unit was checked. Step S1-2, Reference Pressure Calibration: After completing the filter membrane installation and equipment inspection, particle-free water is introduced into the equipment. The suction pump is started and its operating status is adjusted so that the particle-free water flows sequentially through the inlet, suction pump, flow stabilization chamber, flow meter, and multi-stage filter membrane sampling device. By adjusting the operating parameters of the suction pump, the particle-free water is made to flow at the set flow rate. After the water flow rate measured by the flow meter stabilizes, the pressure system of the multi-stage filter membrane sampling device records and calculates the reference pressure difference between the front and back ends of each stage of the individual filter membrane at the corresponding flow rate. ; Steps S1-3: Parameter settings and pre-test confirmation: After completing the benchmark pressure differential calibration, the sampling parameters are set through the data processing control unit. The sampling parameters include the working power of the suction pump, the flow rate of the flow meter, the pressure data acquisition frequency, and the pore size parameters of each stage of the filter membrane. Then, the real-time output signals of the flow meter and the pressure system are checked. Step S2: Indoor pool plume simulation and sampling: Step S2-1, Equipment Deployment: After completing the preparation work for the indoor test, deploy the deep-sea plume in-situ particle size monitoring equipment to the deep-sea mining plume area to be monitored; Step S2-2, Introduction of plume water: After the simulated mining disturbance device is started and a plume of suspended particles is generated, the suction pump is started so that the plume water containing suspended particles enters the equipment through the inlet; the plume water containing suspended particles enters the equipment through the inlet and flows through the suction pump, the flow stabilization chamber, the flow meter and the multi-stage filter membrane sampling device in sequence. Step S2-3, Equipment Recycling: After the preset sampling time or preset sampling volume is reached, the suction pump is turned off to stop the plume of water from entering the equipment. The indoor test equipment is then removed and the sampling process is completed. After the equipment is recovered, the individual filter membranes of each stage in the multi-stage filter membrane sampling device are removed, and data including flow rate, cumulative flow, sampling time, pressure before and after the filter membrane, and pressure difference ΔP are recorded by the flow meter and data processing control unit. Step S3, Data Analysis and Particle Size Result Acquisition: Step S3-1, Data Reading and Processing: After the equipment is recovered, the flow rate, sampling time, cumulative flow rate, and pressure at the front and rear ends of each stage of the filter membrane, as well as the pressure difference, recorded during the sampling process are obtained through a flow meter and a data processing control unit. Simultaneously, the pore size of each stage of the filter membrane and its installation order in the multi-stage filter membrane sampling device are recorded. Based on the "filter membrane pore size-flow rate-flow rate-reference pressure difference" correspondence established in steps S1-2, and using the actual flow rate and cumulative flow rate measured in real time by the flow meter as a basis, the particle-free reference pressure difference for each pore size filter membrane under the same or similar flow rate conditions is selected as the standard value for subsequent calculation of the additional pressure difference for plume particle retention. ; Step S3-2: Calculate the proportion of particles in different particle size ranges: The pressure difference before and after the i-th filter membrane is obtained from the pressure data. The corrected pressure difference after calibrating the pressure difference is: The particulate layer retained on the filter membrane surface is considered as a porous medium, and the corrected pressure difference after calibration by the i-th filter membrane is used. ; Let the pore sizes of the multi-stage filter membranes be arranged from largest to smallest as follows:

[0020] The particle size range corresponding to the i-th filter membrane is:

[0021] The sum of the corrected pressure differences caused by particle retention in all filter membranes is:

[0022] The mass proportion of particles in the i-th size range in the total particles can be expressed as:

[0023] in The mass ratio of particles in the i-th particle size range.

[0024] By employing the above technical solutions, this invention has the following beneficial effects compared to existing technologies: First, this invention, through the combination of a suction pump, a flow stabilization chamber, a flow meter, a multi-stage filter membrane sampling device, and a differential pressure monitoring module, realizes the active introduction, stable flow, graded filtration, and in-situ differential pressure monitoring of deep-sea mining plume water, enabling the monitoring of the entire plume process on the seabed.

[0025] Secondly, by arranging filter membranes of different pore sizes in descending order, the present invention allows the plume particles to be retained step by step according to their particle size, and by using the pressure difference of each filter membrane to correct the proportion of particles in different particle size ranges, the multi-level particle size composition information of the plume particles can be obtained.

[0026] Third, this invention sets up a system that simultaneously collects plume water samples while monitoring in situ using multi-stage filter membranes. After the equipment is recovered, the total mass concentration of the plume water particles can be obtained through filtration, drying, and weighing. This concentration is then combined with the particle size distribution calculated from the pressure difference to achieve quantitative analysis of particle mass in different particle size ranges.

[0027] Fourth, this invention does not rely on optical windows and water transparency, and can adapt to deep-sea high-pressure, low-temperature, high-turbidity and complex flow field environments, making it suitable for deep-sea mining plume diffusion monitoring, environmental impact assessment and ecological risk analysis.

[0028] Additional aspects and advantages of the invention will become apparent in the following description or may be learned by practice of the invention. Attached Figure Description

[0029] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the method flow for in-situ particle size monitoring equipment for deep-sea plumes based on multi-stage filter membrane differential pressure method; Figure 2 A schematic diagram of the internal structure of an in-situ particle size monitoring device for deep-sea mining plumes; Figure 3 A schematic diagram of the overall structure of an in-situ particle size monitoring device for deep-sea mining plumes; Figure 4 This is a schematic diagram of the internal structure of the multi-stage filter membrane sampling device and differential pressure monitoring component. Figure 5 This is a schematic diagram of the multi-stage filter membrane sampling device and differential pressure monitoring components. Figure 6 This is a schematic diagram of a single filter membrane assembly. Figure 7 A schematic diagram showing the deployment of a three-point in-situ monitoring device along the bottom flow direction; in, Figures 2 to 7 The correspondence between the reference numerals and components in the attached drawings is as follows: 1. Base plate, 2. Subsea support frame, 3. Inlet, 4. Protective cover, 5. Suction pump, 6. Flow stabilization chamber, 7. Flow meter, 8. Multi-stage filter membrane sampling device, 9. Main chamber, 10. Drain outlet, 11. Data processing and control unit, 12. Battery compartment, 13. Battery interface, 14. Staged filter membrane assembly, 15. Pressure system, 16. Outlet, 17. Filter membrane fixing buckle, 18. Miniature differential pressure gauge, 19. Front pressure tap, 20. Rear pressure tap, 21. Pressure tapping hose, 22. Upper crossbeam, 23. Hinge, 24. Support ring, 25. Lower support base, 26. Base, 27. Fixing ring, 28. Lock, 29. Single filter membrane. Detailed Implementation

[0030] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0031] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0032] like Figures 2 to 7 As shown, the present invention proposes a deep-sea plume in-situ particle size monitoring device based on multi-stage filter membrane differential pressure method, including a main chamber 9, a suction pump 5 and a seabed support frame 2. The main chamber 9 integrates a flow stabilization chamber 6, a flow meter 7, a multi-stage filter membrane sampling device 8, a differential pressure monitoring component, a data processing and control unit 11 and a battery compartment 12. The front end of the main chamber 9 is equipped with a water inlet 3, and the suction pump 5 is connected to the water inlet 3 to extract deep-sea plume water containing suspended particles and provide power for the water flow. A flow stabilizing chamber 6 is connected in series downstream of the suction pump 5 to weaken the pulsating flow and local turbulence generated by the operation of the suction pump 5, so that the downstream water flow remains stable. The flow meter 7 is connected in series downstream of the flow stabilizing chamber 6 to detect the water flow velocity in real time and output real-time flow rate and cumulative flow rate data. The multi-stage filter membrane sampling device 8 is connected in series downstream of the flow meter 7. The multi-stage filter membrane sampling device 8 is composed of several stages of filter membranes with different pore sizes arranged sequentially along the water flow direction. The pore size of each stage of the filter membrane in the multi-stage filter membrane assembly 14 decreases sequentially from large to small along the water flow direction, so as to intercept suspended particles in the plume according to their particle size. For any stage of filter membrane, when the plume water passes through the filter membrane, particles larger than the pore size of the filter membrane are intercepted by the filter membrane, and particles smaller than the pore size of the filter membrane enter the subsequent filter membrane or discharge channel with the water flow. By sequentially setting filter membranes with different pore sizes, particle content greater than different particle size thresholds can be obtained, and the proportion of particle fractionation content between adjacent particle size thresholds can be further calculated.

[0033] The differential pressure monitoring component is configured one-to-one with each stage of the filter membrane to collect the water pressure on the upstream and downstream sides of the corresponding filter membrane in real time and obtain the pressure difference before and after the filter membrane of that stage. The data processing and control unit 11 is electrically connected to the flow meter 7 and the differential pressure monitoring component, respectively, to collect and store the flow rate, flow rate and pressure difference data of each stage of the filter membrane, and to obtain the content of particles in different particle size ranges according to the preset calculation method. The end of the main chamber 9 is provided with a water discharge outlet 10 to discharge the water after multi-stage filtration. The battery compartment 12 is electrically connected to each electrical component in the main chamber 9 to provide power to the whole equipment. One end of the main chamber 9 is provided with a battery interface 13, which is electrically connected to the charging end of the battery compartment 12 to connect an external power source to charge the battery compartment 12.

[0034] The bottom of the seabed support frame 2 is fixedly installed with a base plate 1 for stable placement of the equipment at the seabed monitoring point.

[0035] A screen is installed on the inlet 3, and a protective cover 4 is also provided on the outside of the inlet 3 to intercept large-sized debris and abnormally large particles, so as to prevent the subsequent flow channel and filter membrane from being blocked.

[0036] The multi-stage membrane sampling device 8 is provided with an outlet 16 at its end, which is connected to the discharge outlet 10. Each stage of the graded membrane assembly 14 consists of replaceable single-piece membranes 29. The graded membrane assembly 14 includes an upper crossbeam 22, a base 26, and a lower support seat 25, a fixing ring 27, and a locking buckle 28, which are the same number of support rings 24 as the number of single-piece membranes 29. The support rings 24 are fixedly mounted on the base 26 via the support seat 25. A single-piece membrane 29 is placed inside the support rings 24. One side of the support rings 24 is hinged to the fixing rings 27 via a hinge 23. The locking buckle 28 is located on the other side of the support rings 24, and the corresponding ends of the locking buckle 28 and the fixing ring 27 are detachably locked together. Each stage of the membrane is also axially limited and fixed by a membrane fixing buckle 17. The base 27 is fixedly installed on the inner wall of the flow channel of the multi-stage membrane sampling device 8. The graded filter membrane assembly 14 is provided with a total of 6 single-piece filter membranes 29, and the pore sizes of each filter membrane along the water flow direction are 75μm, 50μm, 25μm, 10μm, 5μm and 1μm respectively.

[0037] The differential pressure monitoring component includes a pressure system 15 disposed on each stage of the single-piece filter membrane 29. The pressure system 15 includes a front pressure tap 19, a rear pressure tap 20, a pressure tapping hose 21, and a miniature differential pressure gauge 18. The front pressure tap 19 is disposed on the upstream flow channel wall of the corresponding single-piece filter membrane 29, and the rear pressure tap 20 is disposed on the downstream flow channel wall of the corresponding single-piece filter membrane 29. The front pressure tap 19 and the rear pressure tap 20 are respectively connected to the miniature differential pressure gauge 18 through the pressure tapping hose 21. The signal output terminal of the miniature differential pressure gauge 18 is connected to the data processing control unit 11.

[0038] A method for in-situ particle size monitoring of deep-sea plumes based on multi-stage filter membrane differential pressure method specifically includes the following steps: Step S1: Preparation for indoor testing: Step S1-1: Filter membrane installation and equipment inspection: Before conducting in-situ plume particle size monitoring, the deep-sea plume in-situ particle size monitoring equipment was first prepared for indoor testing. Single-layer filter membranes 29 with different pore sizes were sequentially installed in the multi-stage filter membrane sampling device 8, and it was confirmed that the pore size, installation position, and installation sequence of each stage of the single-layer filter membrane 29 met the particle size classification monitoring requirements. The single-layer filter membranes 29 were arranged sequentially in descending order of pore size, ensuring that suspended particles larger than the corresponding filter membrane pore size were intercepted step-by-step after the plume water entered the multi-stage filter membrane sampling device 8, while particles smaller than the corresponding filter membrane pore size were carried by the water flow to the next stage of the filter membrane. After the filter membranes were installed, the connections between the inlet 3, suction pump 5, flow stabilization chamber 6, flow meter 7, multi-stage filter membrane sampling device 8, discharge outlet 10, and data processing control unit 11 were checked to confirm that all components were reliably connected, the pipelines were unblocked, the single-layer filter membranes 29 were tightly installed, and the overall equipment was well-sealed, to avoid affecting subsequent flow velocity measurement, pressure monitoring, and particle size classification results due to loose filter membranes, pipeline leaks, or partial blockages. Step S1-2, Reference Pressure Calibration: After completing the filter membrane installation and equipment inspection, particle-free water is introduced into the equipment. The suction pump 5 is started and its operating status is adjusted so that the particle-free water flows sequentially through the inlet 3, suction pump 5, flow stabilization chamber 6, flow meter 7, and multi-stage filter membrane sampling device 8. By adjusting the operating parameters of suction pump 5, the particle-free water flows under the set flow rate. After the water flow rate measured by flow meter 7 stabilizes, the pressure system 15 of multi-stage filter membrane sampling device 8 records and calculates the reference pressure difference between the front and back ends of each stage of the single filter membrane 29 at the corresponding flow rate. The reference pressure difference is the initial pressure loss generated when particle-free water passes through the currently installed single-piece filter membrane 29 under corresponding flow velocity conditions. It includes the resistance of the single-piece filter membrane 29 itself, the flow resistance of the pipeline, and the inherent pressure loss caused by the water flow. Because the water properties, external pressure, and flow state in the deep-sea in-situ environment differ from the deck calibration conditions, the actual sampling flow velocity under the same suction pump 5 power may vary. Therefore, multiple flow velocity conditions are set under deck conditions, and particle-free water calibration is repeated to establish the correspondence between "flow velocity, filter membrane pore size, and reference pressure difference." During subsequent in-situ monitoring, the filter membrane reference pressure difference under the corresponding flow velocity conditions is selected or calculated based on the water flow velocity measured in real time by the flowmeter 7.

[0039] Steps S1-3: Parameter settings and pre-test confirmation: After completing the baseline pressure differential calibration, sampling parameters are set through the data processing control unit 11. These parameters include the operating power of the suction pump 5, the flow rate of the flow meter 7, the pressure data acquisition frequency, and the pore size parameters of each stage of the single-layer filter membrane 29. Subsequently, the real-time output signals of the flow meter 7 and the pressure system 15 are checked to confirm that the flow rate, pressure, and differential pressure data can be normally acquired and stored by the data processing control unit 11. After confirming that the equipment sealing, power supply, data acquisition, and filter membrane installation are all normal, the preparation work for the indoor test is completed. Step S2: Indoor pool plume simulation and sampling: Step S2-1, Equipment Deployment: After completing the preparation work for the indoor test, deploy the deep-sea plume in-situ particle size monitoring equipment to the deep-sea mining plume area to be monitored; Step S2-2, Introduction of plume water: After the simulated mining disturbance device is started and a plume of suspended particles is generated, the suction pump 5 is started, so that the plume water containing suspended particles enters the equipment through the inlet 3; the plume water containing suspended particles enters the equipment through the inlet 3 and flows through the suction pump 5, the flow stabilizing chamber 6, the flow meter 7 and the multi-stage filter membrane sampling device 8 in sequence; at the same time as the suction pump 5 is started, the protective cover 4 is used to initially intercept the plume water entering the equipment to prevent large-sized debris or abnormal particles from entering the subsequent flow path, so as to avoid pipeline blockage or affecting the normal filtration of the single filter membrane 29.

[0040] Step S2-3, Equipment Recycling: After the preset sampling time or preset sampling volume is reached, the suction pump 5 is turned off to stop the plume of water from entering the equipment. The indoor test equipment is then removed and the sampling process is completed. After the equipment is recovered, the individual filter membranes 29 of each stage in the multi-stage filter membrane sampling device 8 are removed. Data including flow rate, cumulative flow, sampling time, pressure before and after the filter membrane and pressure difference ΔP are recorded by the flow meter 7 and the data processing control unit 11 to provide basic data for subsequent calculation of the content of particles of different sizes. Step S3, Data Analysis and Particle Size Result Acquisition: Step S3-1, Data Reading and Processing: After the equipment is recovered, the flow rate, sampling time, cumulative flow rate, and pressure difference at the front and rear ends of each stage of the single-layer filter membrane 29 are recorded during the sampling process through the flow meter 7 and the data processing control unit 11. Simultaneously, the pore size of each stage of the single-layer filter membrane 29 and its installation order in the multi-stage filter membrane sampling device 8 are recorded. Based on the correspondence between "filter membrane pore size - flow rate - flow rate - reference pressure difference" established in steps S1-2, and using the actual flow rate and cumulative flow rate measured in real time by the flow meter 7 as a basis, the particle-free reference pressure difference of each pore size single-layer filter membrane 29 under the same or similar flow rate conditions is selected as the standard value for subsequent calculation of the additional pressure difference for plume particle interception. ; Step S3-2: Calculate the proportion of particles in different particle size ranges: The pressure difference before and after the i-th filter membrane is obtained from the pressure data. The corrected pressure difference after calibrating the pressure difference is: The particulate layer retained on the filter membrane surface is considered as a porous medium, and the corrected pressure difference after calibration by the i-th filter membrane is used. ; Let the pore sizes of the multi-stage filter membranes be arranged from largest to smallest as follows:

[0041] The particle size range corresponding to the i-th filter membrane is:

[0042] The sum of the corrected pressure differences caused by particle retention in all filter membranes is:

[0043] The mass proportion of particles in the i-th size range in the total particles can be expressed as:

[0044] in This represents the mass ratio of particles in the i-th particle size range. Using the above formula, the pressure ratio of different filter membranes can be further obtained, and thus the particle proportion in different particle size ranges can be determined.

[0045] First, the in-situ particle size monitoring equipment for deep-sea mining plumes is assembled. Single-layer filter membranes 30 with different pore sizes are sequentially installed in the multi-stage filter membrane sampling device 8 in descending order of pore size. In this embodiment, the selected filter membrane pore sizes are 75 μm, 50 μm, 25 μm, 10 μm, 5 μm, and 1 μm. The 75 μm filter membrane is located at the foremost point in the water flow direction, and the 1 μm filter membrane is located at the rearmost point in the water flow direction, ensuring that particles are progressively retained according to particle size as the plume flows through the multi-stage filter membrane sampling module 8.

[0046] After the filter membrane is installed, check the connection status between the inlet 3, suction pump 5, flow stabilizing chamber 6, flow meter 7, multi-stage filter membrane sampling device 8, pressure system 15, data processing control unit 11 and discharge outlet 10 in sequence to confirm that the connection of each component is reliable, the filter membrane is tightly installed, there are no leaks or blockages in the pipeline, and the overall equipment is in good sealing condition.

[0047] After equipment assembly, a simulated deep-sea mining plume diffusion experiment was conducted in a large indoor circulating water tank. A simulated mining vehicle was placed in the center of the tank, with a disturbance mechanism at its bottom to agitate the sediment pre-laid at the bottom of the tank and form a suspended particle plume. A circulating water flow generation system was installed in the tank to diffuse the plume in a predetermined direction. Near-source monitoring areas, mid-range monitoring areas, and long-range monitoring areas were sequentially set along the plume diffusion direction, and particle size monitoring equipment was deployed at each area. Starting from the mining vehicle's operating point, three monitoring points were set up downstream of the bottom current: monitoring point A, monitoring point B, and monitoring point C. Monitoring point A was 10 m from the mining vehicle's operating point, monitoring point B was 50 m from the mining vehicle's operating point, and monitoring point C was 100 m from the mining vehicle's operating point. The inlets 3 of all three monitoring points faced the direction of the bottom current flow, enabling the equipment to collect the mining plume water transported by the bottom current.

[0048] After the equipment reaches the predetermined monitoring location, the 5-suction pump is first operated at low power to allow water to slowly enter the equipment. Once the flow rate recorded by the flowmeter 7 reaches a stable state, formal sampling begins. During formal sampling, the water flow rate inside the equipment is controlled within a set range, and the pressure difference before and after each stage of the filter membrane is continuously recorded. In this embodiment, the sampling period is 10 days. The first hour after sampling begins is used for equipment flow path stabilization and pressure response stabilization, followed by a stable sampling phase where data from the flowmeter 7 and pressure system 15 are continuously recorded.

[0049] After sampling, the 5-suction pump was shut off to stop the plume of water from entering the equipment, and the equipment at the three monitoring points was retrieved to the deck. After retrieval, the water flow velocity, sampling time, cumulative flow, pressure at the front end of each stage of the 29-single filter membrane, and pressure difference data recorded during the sampling process were exported through the 11-data processing control unit. Simultaneously, the pore size of each stage of the single filter membrane 29 and its installation sequence in the multi-stage filter membrane sampling device 8 were recorded.

[0050] The pressure data obtained from in-situ observations can yield the first... The pressure difference across the filter membrane, and the corrected pressure difference after calibration of this pressure difference, are:

[0051] Among them, is the first The pressure difference before and after the filter membrane was measured during in-situ sampling. This is the reference pressure difference for the filter membrane under particulate-free water conditions. This is the corrected pressure difference caused by particle retention after deducting the reference pressure difference.

[0052] Since the particle layer retained on the filter membrane surface can be considered as a porous medium, according to Darcy's law, it can be derived from the first... The pressure difference after calibration of each filter membrane reflects the amount of particles of the corresponding particle size that the filter membrane can retain.

[0053] Let the pore sizes of the multi-stage filter membranes be arranged from largest to smallest as follows:

[0054] In this embodiment, the pore sizes of the multi-stage filter membranes are as follows:

[0055] No. The particle size range corresponding to each filter membrane is:

[0056] Therefore, in this embodiment, the particle size ranges corresponding to each filter membrane are as follows: 75 μm filter membrane corresponds to particles larger than 75 μm; 50 μm filter membrane corresponds to particles of 50–75 μm; 25 μm filter membrane corresponds to particles of 25–50 μm; 10 μm filter membrane corresponds to particles of 10–25 μm; 5 μm filter membrane corresponds to particles of 5–10 μm; and 1 μm filter membrane corresponds to particles of 1–5 μm.

[0057] The sum of the corrected pressure differences caused by particle retention in all filter membranes is:

[0058] Then the first The mass proportion of particles in each size range in the total particles can be expressed as:

[0059] in, For the first The mass ratio of particles in each particle size range can be obtained using the above formula. Furthermore, the pressure ratio of different filter membranes can be obtained, and the proportion of particles in different particle size ranges can be further determined.

[0060] For monitoring point A, which is 10 m away from the mining vehicle:

[0061] In the description of this invention, the term "a plurality of" refers to two or more. Unless otherwise explicitly defined, the terms "upper," "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. The terms "connection," "installation," "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0062] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0063] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A deep-sea plume in-situ particle size monitoring device based on multi-stage filter membrane differential pressure method, comprising a main chamber (9), a suction pump (5), and a seabed support frame (2), characterized in that, The main compartment (9) integrates a flow stabilization chamber (6), a flow meter (7), a multi-stage filter membrane sampling device (8), a differential pressure monitoring component, a data processing control unit (11), and a battery compartment (12). The front end of the main chamber (9) is provided with a water inlet (3), and the suction pump (5) is connected to the water inlet (3); The flow stabilizing chamber (6) is connected in series downstream of the suction pump (5), the flow meter (7) is connected in series downstream of the flow stabilizing chamber (6), the multi-stage filter membrane sampling device (8) is connected in series downstream of the flow meter (7), and the multi-stage filter membrane sampling device (8) is arranged in sequence along the water flow direction with a number of filter membranes of different pore sizes forming a graded filter membrane assembly (14), and the pore size of each filter membrane in the graded filter membrane assembly (14) decreases from large to small along the water flow direction. The differential pressure monitoring component is configured one-to-one with each level of filter membrane. The data processing control unit (11) is electrically connected to the flow meter (7) and the differential pressure monitoring component respectively. The end of the main chamber (9) is provided with a water discharge outlet (10). The battery chamber (12) is electrically connected to each electrical component in the main chamber (9). One end of the main chamber (9) is provided with a battery interface (13). The battery interface (13) is electrically connected to the charging end of the battery chamber (12) for connecting an external power source to charge the battery chamber (12).

2. The in-situ particle size monitoring device for deep-sea plumes based on multi-stage filter membrane differential pressure method according to claim 1, characterized in that, The bottom end of the seabed support frame (2) is fixedly installed with a base plate (1).

3. The in-situ particle size monitoring device for deep-sea plumes based on multi-stage filter membrane differential pressure method according to claim 1, characterized in that, A screen is installed on the inlet (3), and a protective cover (4) is also provided on the outside of the inlet (3).

4. The in-situ particle size monitoring device for deep-sea plumes based on multi-stage filter membrane differential pressure method according to claim 1, characterized in that, The multi-stage filter membrane sampling device (8) is provided with an outlet (16) at its end, and the outlet (16) is connected to the discharge outlet (10).

5. The in-situ particle size monitoring device for deep-sea plumes based on multi-stage filter membrane differential pressure method according to claim 4, characterized in that, The graded filter membrane assembly (14) consists of replaceable single-piece filter membranes (29) at each stage. The graded filter membrane assembly (14) includes an upper crossbeam (22), a base (26), and a support ring (24) with the same number of support rings (24) as the single-piece filter membranes (29), a lower support seat (25), a fixing ring (27), and a latch (28). The support ring (24) is fixedly installed on the base (26) through the support seat (25). A single-piece filter membrane (29) is placed inside the support ring (24). One side of the support ring (24) is hinged to the fixing ring (27) through a hinge (23). The latch (28) is located on the other side of the support ring (24). The corresponding end of the latch (28) is detachably locked to the fixing ring (27). Each stage of the filter membrane is also axially limited and fixed by the filter membrane fixing buckle (17), and the base (26) is fixedly installed on the inner wall of the flow channel of the multi-stage filter membrane sampling device (8).

6. The in-situ particle size monitoring device for deep-sea plumes based on multi-stage filter membrane differential pressure method according to claim 5, characterized in that, The graded filter membrane assembly (14) is provided with a total of 6 levels of single filter membranes (29), and the pore sizes of each level of filter membrane along the water flow direction are 75μm, 50μm, 25μm, 10μm, 5μm and 1μm respectively.

7. The in-situ particle size monitoring device for deep-sea plumes based on multi-stage filter membrane differential pressure method according to claim 5, characterized in that, The differential pressure monitoring component includes a pressure system (15) installed on each stage of the single-layer filter membrane (29). The pressure system (15) includes a front pressure tap (19), a rear pressure tap (20), a pressure tapping hose (21), and a miniature differential pressure gauge (18). The front pressure tap (19) is located on the upstream flow channel wall of the corresponding single-layer filter membrane (29), and the rear pressure tap (20) is located on the downstream flow channel wall of the corresponding single-layer filter membrane (29). The front pressure tap (19) and the rear pressure tap (20) are respectively connected to the miniature differential pressure gauge (18) through the pressure tapping hose (21). The signal output terminal of the miniature differential pressure gauge (18) is connected to the data processing control unit (11).

8. A method for in-situ particle size monitoring of deep-sea plumes based on multi-stage membrane differential pressure method as described in claims 1 to 7, characterized in that... Specifically, it includes the following steps: Step S1: Preparation for indoor testing: Step S1-1: Filter membrane installation and equipment inspection: Before conducting in-situ plume particle size monitoring, the deep-sea plume in-situ particle size monitoring equipment was first prepared for an indoor test. Single-layer filter membranes (29) with different pore sizes were installed in the multi-stage filter membrane sampling device (8) in sequence, and the pore size, installation position and installation sequence of each level of single-layer filter membrane (29) were confirmed. The single-layer filter membranes (29) were arranged in sequence from large to small pore size, so that after the plume water enters the multi-stage filter membrane sampling device (8), suspended particles larger than the corresponding filter membrane pore size can be intercepted step by step, and particles smaller than the corresponding filter membrane pore size can enter the next level filter membrane with the water flow. After the filter membrane is installed, the connection relationship between the inlet (3), suction pump (5), flow stabilization chamber (6), flow meter (7), multi-stage filter membrane sampling device (8), discharge outlet (10) and data processing control unit (11) is checked. Step S1-2, Reference Pressure Calibration: After completing the filter membrane installation and equipment inspection, the particle-free water is introduced into the equipment. The suction pump (5) is started and its working state is adjusted so that the particle-free water flows sequentially through the inlet (3), suction pump (5), flow stabilization chamber (6), flow meter (7), and multi-stage filter membrane sampling device (8). By adjusting the working parameters of the suction pump (5), the particle-free water flows under the set flow rate. After the water flow rate measured by the flow meter (7) stabilizes, the pressure system (15) of the multi-stage filter membrane sampling device (8) is used to record and calculate the reference pressure difference between the front and back ends of each stage of the single filter membrane (29) at the corresponding flow rate. ; Steps S1-3: Parameter settings and pre-test confirmation: After completing the benchmark pressure difference calibration, the sampling parameters are set through the data processing control unit (11). The sampling parameters include the working power of the suction pump (5), the flow rate of the flow meter (7), the pressure data acquisition frequency, and the pore size parameters of each stage of the single filter membrane (29). Then, the real-time output signals of the flow meter (7) and the pressure system (15) are checked. Step S2: Indoor pool plume simulation and sampling: Step S2-1, Equipment Deployment: After completing the preparation work for the indoor test, deploy the deep-sea plume in-situ particle size monitoring equipment to the deep-sea mining plume area to be monitored; Step S2-2, Introduction of plume water: After the simulated mining disturbance device is started and a plume of suspended particles is generated, the suction pump (5) is started so that the plume water containing suspended particles enters the equipment through the inlet (3); the plume water containing suspended particles enters the equipment through the inlet (3) and flows through the suction pump (5), the flow stabilization chamber (6), the flow meter (7) and the multi-stage filter membrane sampling device (8) in sequence. Step S2-3, Equipment Recycling: After the preset sampling time is reached or the preset sampling volume is completed, the suction pump (5) is turned off, the plume of water continues to enter the equipment, and the indoor test equipment is taken out and the sampling process ends. After the equipment is recovered, the single filter membranes (29) of each stage in the multi-stage filter membrane sampling device (8) are taken out, and the flow rate, cumulative flow, sampling time, pressure before and after the filter membrane and pressure difference ΔP data are recorded by the flow meter (7) and the data processing control unit (11). Step S3, Data Analysis and Particle Size Result Acquisition: Step S3-1, Data Reading and Processing: After the equipment is recovered, the water flow rate, sampling time, cumulative flow rate, front-end pressure, back-end pressure and pressure difference of each stage of single-layer filter membrane (29) recorded during the sampling process are obtained through the flow meter (7) and the data processing control unit (11). At the same time, the pore size of each stage of single-layer filter membrane (29) and its installation order in the multi-stage filter membrane sampling device (8) are recorded. According to the correspondence between "filter membrane pore size-flow rate-flow rate-baseline pressure difference" established in steps S1-2, the particle-free baseline pressure difference of each pore size single-layer filter membrane (29) under the same or similar flow rate conditions is selected as the standard value for subsequent calculation of the additional pressure difference of plume particle interception. ; Step S3-2: Calculate the proportion of particles in different particle size ranges: The pressure difference before and after the i-th filter membrane is obtained from the pressure data. The corrected pressure difference after calibrating the pressure difference is: The particulate layer retained on the filter membrane surface is considered as a porous medium, and the corrected pressure difference after calibration by the i-th filter membrane is used. ; Let the pore sizes of the multi-stage filter membranes be arranged from largest to smallest as follows: ， The particle size range corresponding to the i-th filter membrane is: ， The sum of the corrected pressure differences caused by particle retention in all filter membranes is: ， The mass proportion of particles in the i-th size range in the total particles can be expressed as: ， in The mass ratio of particles in the i-th particle size range.

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