An underwater in-situ voltammetric analyzer with full shielding structure and method supporting quick mounting and dismounting of a measuring unit

Abstract

The application discloses a kind of full shielding structure underwater in-situ volt-ampere analyzers and methods supporting the quick assembly and disassembly of measuring unit, comprising: oil-filled cabin, first shielding cover is arranged in the inside, the sampling unit includes multistage filter head of oil-filled cabin outer wall and its communicating delivery pipeline, delivery pipeline is communicated with volt-ampere measuring unit, peristaltic pump and solenoid valve are arranged on pipeline;First shielding cover covers oil-filled cabin inner wall;Volt-ampere measuring unit quick mounting position is arranged on the outer wall of oil-filled cabin;Medium oil bladder is communicated with oil-filled cabin, and filled with medium oil;Volt-ampere measuring unit is installed in quick mounting position;Pressure control cabin is connected with oil-filled cabin, and gold-plated copper needle is arranged at the joint, and control circuit board is arranged in pressure control cabin;Volt-ampere measuring unit is connected with one end of gold-plated copper needle through shielding wire, and the other end of gold-plated copper needle is connected with control circuit board through shielding wire.The application realizes the quick assembly and disassembly of volt-ampere measuring unit, and the shielding structure improves measurement accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underwater electrochemical analysis equipment, in particular to a full-shield structure underwater in-situ voltammetry analyzer supporting quick mounting and dismounting of a measuring unit and a method thereof, which is suitable for in-situ detection of trace metal ions in a deep sea environment. BACKGROUND

[0002] In marine environment monitoring, in-situ and online quantification of trace metals and other pollutants in seawater is of key significance. Traditional shore-based laboratory analysis relies on off-shore sampling and off-site pretreatment / determination, but at ppb (μg·L -1 ) concentration level, any contact of the sample with metal devices or pipelines during collection, sub-packaging and transportation may introduce trace metal leaching and cross contamination; at the same time, the dissolution / complexation equilibrium of elements such as Zn, Cd, Pb, Cu, Fe and Mn is highly sensitive to pressure (depth) and temperature, and post-harvest condition changes easily induce species transformation and concentration deviation, making it difficult to guarantee sample authenticity and introducing additional uncertainty. In order to overcome the above limitations, it is urgent to develop an integrated in-situ analyzer that can complete sampling-pretreatment-voltammetry determination directly underwater, to realize low detection limit (LOD), high accuracy and high spatiotemporal resolution monitoring of trace heavy metals, and to minimize post-harvest effects and secondary pollution.

[0003] However, there are still many technical challenges in actual underwater measurement scenarios. Firstly, due to the extremely small ion concentration of heavy metals in conventional seawater, the current obtained by using voltammetry detection is in the order of nanoamperes, so the measurement instrument deployed in the marine environment is easily affected by external electromagnetic interference (EMI). For example, the electromagnetic noise interference generated by underwater remotely operated vehicles (ROVs) and sonar systems and other equipment during operation will interfere with the precise electrochemical sensing signal. Voltammetry is based on the detection principle of weak current signals, and has extremely high sensitivity to environmental electromagnetic interference. If the shielding measures are not perfect, the noise such as power frequency interference and motor stray current in the environment can easily invade the measurement circuit through the coupling path, resulting in a decrease in signal-to-noise ratio (SNR) and deterioration of measurement accuracy. Electrochemical measurement in a laboratory environment often builds an electromagnetic shielding space with a Faraday cage to isolate external interference; related studies have shown that if the wire is directly penetrated through the shielding cage without shielding treatment, it will become a key coupling channel for introducing power frequency interference into the weak signal measurement system. However, in the design scenario of miniaturization of underwater measurement equipment, it is difficult to realize such a fully enclosed electromagnetic shielding structure.

[0004] Secondly, the long-term underwater deployment of voltammetric analyzer needs to consider the convenience of maintaining and replacing the sensing components. The only commercial in-situ heavy metal sensor on the market, the Italian Idronaut company developed the diving voltammetric in-situ profiler (VIP) system, in order to ensure the shielding effect of the measurement unit, the electrode measurement unit is wrapped in the cavity with a shielding cover. For this kind of oil-filled cabin structure, once the sensor probe needs to be replaced or checked, there are usually two inconvenient schemes: one is to replace it after discharging all the cabin oil, which is time-consuming and laborious; the second is to directly disassemble the sensor when the oil is not empty, but it is inevitable to cause oil leakage into the measurement flow path, causing flow path pollution. For example, some documents mention that the traditional oil monitoring sensor device installed on the side wall will inevitably cause oil leakage at the installation hole when replaced. This not only wastes oil and pollutes the environment, but also may damage the internal seal and pressure balance of the instrument.

[0005] Furthermore, marine observation equipment usually has clear requirements for long-term continuous operation capability and reduction of on-site maintenance frequency. Especially in deep sea and offshore platform scenarios, equipment recovery and frequent replacement of components have high operation and maintenance costs. Therefore, how to realize the non-oil discharge quick replacement of underwater sensing units has become a key research direction to improve the practicality of the instrument. Based on this, the development of a voltammetric measurement unit with external interference shielding capability and underwater quick assembly and disassembly characteristics will effectively improve the performance indicators and maintenance efficiency of the underwater voltammetric analyzer, and meet the application requirements of long-term online monitoring of the sea. SUMMARY

[0006] The present application aims to overcome the defects of insufficient anti-electromagnetic interference capability and difficult replacement of measurement units of existing underwater in-situ voltammetric analyzers, and provides a full-shielded structure underwater in-situ voltammetric analyzer and method supporting quick assembly and disassembly of measurement units. The analyzer can realize modular quick disassembly and assembly of the voltammetric measurement unit without releasing the oil in the oil-filled cabin, and significantly improve the signal-to-noise ratio and measurement accuracy of underwater electrochemical weak current measurement through full-link shielding and single-point grounding.

[0007] To achieve the above purpose, the present application provides the following technical solutions:

[0008] A full-shielded structure underwater in-situ voltammetric analyzer supporting quick assembly and disassembly of measurement units, comprising: an oil-filled cabin, a medium oil bladder, a voltammetric measurement unit, and a pressure-resistant control cabin.

[0009] The oil filling cabin is provided with a sample inlet unit and a first shielding cover, the sample inlet unit comprises a multi-stage filter head, a peristaltic pump, an electromagnetic valve and a conveying pipeline, the multi-stage filter head is arranged on the outer wall of the oil filling cabin and used for removing suspended particle interference in the sample to be measured, reducing background noise of the voltammetry measurement and the risk of electrode surface pollution, one end of the conveying pipeline is communicated with the multi-stage filter head, the other end is communicated with the voltammetry measurement unit, and the peristaltic pump and the electromagnetic valve are arranged on the conveying pipeline; the first shielding cover covers the inner wall of the oil filling cabin; the voltammetry measurement unit quick mounting position is arranged on the side wall of the oil filling cabin.

[0010] The medium oil bag is fixedly communicated with the oil filling cabin to realize pressure compensation, the oil filling cabin is filled with medium oil to realize electrical insulation.

[0011] The voltammetry measurement unit is mounted on the voltammetry measurement unit quick mounting position and used for voltammetry measurement of the sample to be measured.

[0012] The pressure control cabin is fixedly connected with the oil filling cabin, a cabin-penetrating gold-plated copper needle is arranged at the fixed connection position, the pressure control cabin is provided with an energy storage battery pack and a control circuit board.

[0013] The voltammetry measurement unit is connected with one end of the cabin-penetrating gold-plated copper needle through a shielding wire, the other end of the cabin-penetrating gold-plated copper needle is connected with the control circuit board through a shielding wire, and data transmission is realized.

[0014] Further, the voltammetry measurement unit comprises a voltammetry measurement cell, a peek inverted taper joint, a hose and hard pipe butt joint, a working electrode, a reference electrode and an auxiliary electrode.

[0015] The structure of the voltammetry measurement cell is divided into two functional areas, i.e., a sample flow area and a pressure balance oil seal area, the sample flow area is used for flow, enrichment and voltammetry measurement of the sample to be measured, and the pressure balance oil seal area is used for communication with the oil filling cavity to realize pressure compensation and provide an electrical insulation environment.

[0016] The sensing ends of the working electrode, the reference electrode and the auxiliary electrode are arranged in the sample flow area, the electrical connection ends thereof are arranged in the pressure balance oil seal area, an O-shaped sealing ring is arranged between the two areas and used for static sealing isolation, so that direct contact between the oil seal side medium and the seawater sample is avoided and the cross contamination risk is eliminated;

[0017] The peek inverted taper joint is communicated with the sample flow area of the voltammetry measurement cell, one end of the hose and hard pipe butt joint is communicated with the peek inverted taper joint, and the other end is communicated with the conveying pipeline.

[0018] Further, the voltammetry measurement unit and the voltammetry measurement unit quick mounting position are connected through bolts, and a sealing ring is arranged at the contact position of the voltammetry measurement unit and the oil filling cabin.

[0019] Further, the pressure-resistant control cabin is further provided with a watertight connector and a thermocouple;

[0020] The watertight connector is connected with the control circuit board, and is used for external communication and synchronous control;

[0021] The other end of the cabin-penetrating gold-plated copper needle is connected with the control circuit board through a shielding wire, specifically connected with an electrode signal receiving end of the control circuit board, and the electrode signal receiving end is covered by a second shielding cover to form electromagnetic shielding;

[0022] The thermocouple is used for environmental temperature monitoring and voltammetry temperature compensation.

[0023] Further, the oil-filled cabin includes an oil-filled cavity, an oil-filled cavity end cover and a first connection end cover respectively arranged at two ends of the oil-filled cavity, the multi-stage filter head is arranged on the oil-filled cavity end cover, and the voltammetry measurement unit quick mounting position is arranged on the oil-filled cavity;

[0024] The pressure-resistant control cabin includes a pressure-resistant control cavity and a second connection end cover and a temperature measurement end cover respectively arranged at two ends of the pressure-resistant control cavity, and the watertight connector and the thermocouple are arranged on the temperature measurement end cover;

[0025] The first connection end cover and the second connection end cover are fixedly connected through threads, so as to realize the connection of the oil-filled cabin and the pressure-resistant control cabin.

[0026] Further, the peristaltic pump adopts an in-pipe flow structure, so that the to-be-measured sample only contacts the inner surface of the conveying pipeline, and potential metal leaching or cross contamination of other components of the pump body on the to-be-measured sample is effectively avoided.

[0027] Further, the medium oil is silicon oil, the material of the conveying pipeline is PTFE or FEP material, and the cabin-penetrating gold-plated copper needle is sealed and held by epoxy resin.

[0028] The measurement method of the full-shielding structure underwater in-situ voltammetry analyzer supporting quick mounting and dismounting of the measurement unit according to any one of the embodiments includes the following steps:

[0029] 1) Pre-mounting the voltammetry measurement unit on the voltammetry measurement unit quick mounting position, and placing the underwater in-situ voltammetry analyzer in a test water body;

[0030] 2) Control circuit board reads thermocouple to complete self-test and temperature compensation setting; and controls electromagnetic valve to open conveying pipeline, opens peristaltic pump, extracts sample to be measured from test water body and sends it into voltammetry measuring cell through multi-stage filter head; after reaching set volume and residence time, executes enrichment, standing and scanning sequence, collects current / potential data of working electrode, reference electrode and auxiliary electrode to control circuit board, and transmits measuring data back to computer through water-tight connector; after measurement, enters next cycle of measurement or standby.

[0031] Further, when the voltammetry measuring unit needs to be replaced, the voltammetry measuring unit fast mounting position opening is upward, the voltammetry measuring unit is disassembled and a new voltammetry measuring unit is replaced.

[0032] Compared with the prior art, the beneficial effects of the present application are:

[0033] Significant improvement in maintainability: by arranging the voltammetry measuring unit which can be quickly mounted and dismounted on the side wall of the oil-filled cavity, the water can be quickly replaced, and the whole process does not need to be drained, vacuumed and refilled with oil, effectively shortening the maintenance cycle and reducing the operation complexity and environmental risk.

[0034] Enhanced electromagnetic anti-interference capability: full shielding structure and single-point grounding strategy are adopted, and shielding continuity is established between three electrodes (working electrode, reference electrode and auxiliary electrode) - shielding cover - shielding wire - trans-cabin gold-plated copper needle - control circuit board, which can effectively suppress common mode / differential mode interference under long cable power supply, pump valve driving and seawater environment, significantly improving the signal-to-noise ratio and measurement stability of weak current voltammetry signal.

[0035] Improved sample authenticity and measurement accuracy: multi-stage filter head and in-pipe flow path design reduce interference introduced by particles and metal leaching; the sample flow area and pressure balance oil seal area of the voltammetry measuring cell are effectively isolated by the O-shaped sealing ring, avoiding direct contact between the oil seal medium and the sample, eliminating cross contamination from the source; the enrichment-voltammetry determination process is completed in situ, reducing the deviation caused by post-harvest morphological changes and secondary pollution.

[0036] Strong engineering adaptability: the modular measuring unit fast mounting structure facilitates quick replacement and upgrade of different electrode types and ranges, meeting the needs of multi-scenario sea trial and long-term deployment.

[0037] Corrosion-resistant and low-elution fluid connection system: the butt joint of the peek inverted taper connector and the soft tube is directly connected with the PTFE or FEP inert pipe, which forms a low-absorption, low-elution seawater-resistant flow path, taking into account pressure sealing and quick assembly, reducing leakage and dead volume.

[0038] Temperature measurement and measurement compensation link: the temperature measuring end cover is provided with a thermocouple which provides real-time temperature input to the control circuit board for temperature compensation and threshold correction of voltammetry measurement, reducing the influence of environmental temperature change on the dissolution / enrichment kinetics and electrode potential.

[0039] High reliability through-penetration electrical connection and sealing: the through-penetration gold-plated copper needle is sealed by epoxy resin, has low contact resistance, pressure sealing and corrosion resistance, and is a reliable shielding / grounding connection point, which improves the environmental stress resistance of the whole machine, and the structure is tested by hydrostatic pressure and can be used in 4500m water depth;

[0040] Voltage stabilization and insulation: by filling medium oil in the oil-filled cavity, and setting the medium oil bag in communication with the oil-filled cavity, the pressure in the oil-filled cavity changes synchronously with the external sea pressure, ensuring the normal work of the sampling unit, and the medium oil has good insulation effect. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 The whole structure schematic diagram of an embodiment of the application is shown in the figure;

[0042] Figure 2 The structure schematic diagram of another direction of an embodiment of the application is shown in the figure;

[0043] Figure 3 The pressure-resistant control cabin structure schematic diagram of an embodiment of the application is shown in the figure;

[0044] Figure 4 The oil-filled cabin structure schematic diagram of an embodiment of the application is shown in the figure;

[0045] Figure 5 The structure schematic diagram of a voltammetry measurement unit of an embodiment of the application is shown in the figure;

[0046] Figure 6 The result schematic diagram of measuring seawater three times of an embodiment of the application is shown in the figure;

[0047] In the figure: 1, watertight connector; 2, pressure-resistant control cabin; 3, oil-filled cabin; 4, medium oil bag; 5, temperature measuring end cover; 6, thermocouple; 7, pressure-resistant control cavity; 8, circuit board mounting disc; 9, control circuit board; 10, mounting plate; 11, energy storage battery pack; 12, first connecting end cover; 13, through-penetration gold-plated copper needle; 14, multi-stage filter head; 15, voltammetry measurement unit; 16, oil-filled cavity; 17, first shielding cover; 18, oil-filled cavity end cover; 19, medium oil bag adapter; 20, support; 21, peristaltic pump; 22, peristaltic pump mounting plate; 23, two-position three-way electromagnetic valve; 24, electromagnetic valve mounting plate; 25, voltammetry measurement pool; 26, peek inverted taper joint; 27, hose and hard pipe butt joint; 28, working electrode; 29, reference electrode; 30, auxiliary electrode; 31, second connecting end cover. DETAILED DESCRIPTION

[0048] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below, obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0049] According to a specific example of the present application, a full-shield structure underwater in-situ voltammetry analyzer supporting quick mounting and dismounting of a measurement unit comprises an oil-filled cabin body 3, a medium oil bladder 4, a voltammetry measurement unit 15 and a pressure-resistant control cabin body 2.

[0050] The oil-filled cabin body 3 is provided with a sampling unit and a first shield 17, the sampling unit comprises a multi-stage filter head 14, a peristaltic pump 21, an electromagnetic valve and a conveying pipeline, the multi-stage filter head 14 is arranged on the outer wall of the oil-filled cabin body 3, one end of the conveying pipeline is communicated with the multi-stage filter head 14, the other end is communicated with the voltammetry measurement unit 15, and the peristaltic pump 21 and the electromagnetic valve are arranged on the conveying pipeline; the first shield 17 covers the inner wall of the oil-filled cabin body 3; a voltammetry measurement unit quick mounting position is arranged on the side wall of the oil-filled cabin body.

[0051] The medium oil bladder 4 is fixedly communicated with the oil-filled cabin body 3, and the oil-filled cabin body 3 and the medium oil bladder 4 are filled with medium oil.

[0052] The voltammetry measurement unit 15 is installed in the voltammetry measurement unit quick mounting position and used for performing voltammetry measurement on a sample to be measured.

[0053] The pressure-resistant control cabin body 2 is fixedly connected with the oil-filled cabin body 3, a cabin-penetrating gold-plated copper needle 13 is arranged at the fixed connection position, and the pressure-resistant control cabin body 2 is provided with an energy storage battery group 11 and a control circuit board 9.

[0054] The voltammetry measurement unit 15 is connected with one end of the cabin-penetrating gold-plated copper needle 13 through a shielded wire, the other end of the cabin-penetrating gold-plated copper needle 13 is connected with the control circuit board 9 through a shielded wire, and data transmission is realized.

[0055] Embodiment:

[0056] 1. Overall structure

[0057] Please refer to Figures 1-5 The present application provides a full-shield structure underwater in-situ voltammetry analyzer supporting quick mounting and dismounting of a measurement unit, which is composed of a pressure-resistant control cabin body 2 and an oil-filled cabin body 3 fixedly connected with the pressure-resistant control cabin body 2.

[0058] The circuit board mounting disc 8, the control circuit board 9, the mounting plate 10 and the energy storage battery pack 11 are sequentially arranged in the pressure-resistant control cabin body 2; the second connecting end cover 31 is threadedly and sealingly connected with the first connecting end cover 12 of the oil-filled cabin body 3 at the front end of the pressure-resistant control cabin body 2, and 11 gold-plated copper needles 13 are fixedly arranged on the second connecting end cover 31 as power supply and signal channels. The watertight connector 1 is arranged outside the pressure-resistant control cabin body 2 and used for external communication and synchronous control. The other end of the pressure-resistant control cabin body 2 is the temperature measuring end cover 5, and the thermocouple 6 is arranged in the temperature measuring end cover 5 and used for environmental temperature monitoring and temperature compensation of voltammetric measurement.

[0059] The oil-filled cabin body 3 is filled with silicone oil and is provided with the medium oil bladder 4 and the adapter 19 to realize external pressure compensation; the oil-filled cabin body 3 comprises the oil-filled cavity 16 and the first connecting end cover 12 and the oil-filled cavity end cover 18 respectively arranged at two ends of the oil-filled cavity 16. The oil-filled cavity 16 is provided with a quick mounting position of the voltammetric measurement unit on the side wall, and is used for mounting the voltammetric measurement unit 15. In order to realize the continuity of electromagnetic shielding, the first shielding cover 17 is arranged inside the oil-filled cabin body 3, and the side wall of the first shielding cover 17 is only provided with limiting holes for the working electrode 28, the reference electrode 29, the auxiliary electrode 30 of the voltammetric measurement unit 15 and internal pipelines to pass through, so as to minimize the gap coupling and radiation leakage, cooperate with the shielding wire transition, and reduce the coupling of electromagnetic interference on the high-impedance node at the front end.

[0060] In terms of the fluid execution unit, the oil-filled cabin body 3 is provided with a multi-stage filter head 14, a peristaltic pump 21 and an electromagnetic valve, wherein the electromagnetic valve adopts a two-position three-way electromagnetic valve 23; the peristaltic pump mounting plate 22 and the electromagnetic valve mounting plate 24 and the support 20 for bearing and anti-vibration are correspondingly arranged. The fluid connection adopts a peek inverted taper joint 26 and a hose hard pipe butt joint 27 to realize corrosion resistance, low outgassing and reliable sealing.

[0061] 2, fluid path and measurement cell structure

[0062] After the seawater sample enters the multi-stage filter head 14 for filtration through the water inlet, the sample enters the peristaltic pump 21 through the delivery pipeline. The peristaltic pump 21 adopts an in-pipe flow path design to ensure that the sample only contacts the pump pipe, thereby avoiding metal leaching of the pump body components on the sample. After the peristaltic pump 21, the two-position three-way electromagnetic valve 23 is switched to realize time sequence control of the sample entering different delivery pipelines of the voltammetric measurement cell 25. Finally, the hose hard pipe butt joint 27 is connected with the peek inverted taper joint 26 after the delivery pipeline and the hose hard pipe butt joint 27 are connected, so as to guide the sample into the voltammetric measurement cell 25. Preferably, the volumetric flow rate of the peristaltic pump 21 is set to 2 mL / min and can be adjusted within the range of 0.1-8 mL / min to adapt to different enrichment time and noise control requirements.

[0063] The peek reverse taper joint 26 is used for the connection between the fluid nodes and the hose hard tube interface 27, and the pipeline material is preferably PEEK / PTFE / FEP to reduce adsorption and precipitation. The waste liquid is discharged or collected through a separate pipeline.

[0064] The voltammetry cell 25 is divided into two parts: a sample flow area and a pressure balance oil seal area.

[0065] Sample flow area: The sensing section (immersed section) of the working electrode 28, reference electrode 29, and auxiliary electrode 30 is set to realize sample enrichment and voltammetry test.

[0066] Pressure balance oil seal area: Communicates with the oil-filled cavity 16 and fills with silicone oil, serving as an electrical insulation and pressure compensation cavity for electrode leads and interfaces.

[0067] O-shaped sealing rings are used for static sealing and isolation between the two areas to prevent direct contact between silicone oil and seawater samples, which may cause cross contamination. The electrical connection end of the three electrodes (working electrode 28, reference electrode 29, and auxiliary electrode 30) in the voltammetry cell 25 communicates with the oil-filled cavity 16, which communicates with the medium oil bladder 4 to ensure that the pressure in the oil-filled cavity changes synchronously with the external sea pressure, ensuring the normal operation of the peristaltic pump 21. The voltammetry cell 25 has two reserved pipeline holes on both sides to facilitate the orderly arrangement and stress release of sample waste liquid pipelines and flushing pipelines. The voltammetry cell 25 and the oil-filled cavity 16 are connected by four bolts and two sealing rings, which can be disassembled and reassembled without releasing the silicone oil in the cabin when the voltammetry cell is opened upward, significantly reducing maintenance time and reducing the risk of secondary pollution and sealing.

[0068] 3. Electrical connection, shielding, and grounding

[0069] The electrode signal receiving end of the control circuit board 9 is covered by a separate second shielding cover to form a local Faraday cage, and the shielding cover 17 is connected to the signal ground of the control circuit board 9 through a cabin-penetrating gold-plated copper needle 13. The leads of the three electrodes (working electrode 28, reference electrode 29, and auxiliary electrode 30) use shielded wires, which are connected to the control circuit board 9 through the first shielding cover 17 and the cabin-penetrating gold-plated copper needle 13. The communication circuit corresponding to the watertight connector 1 and the shell adopt a star single-point grounding strategy to suppress common-mode and differential-mode interference. If necessary, π-type filters and common-mode chokes are arranged at the cabin-penetrating position to further improve the signal-to-noise ratio of weak current measurement. The thermocouple 6 signal is input to the control circuit board 9 after isolation / filtering for temperature compensation of voltammetry measurement.

[0070] 4. Sealing and pressure compensation

[0071] The first connecting end cover 12, the second connecting end cover 31, the pressure-resistant control cavity 7, the oil-filled cavity 16, the oil-filled cavity end cover 18, and the connection surface of the volt-ampere measurement unit 15 and the oil-filled cavity 16 are all provided with two sealing grooves and are equipped with O-shaped sealing rings made of FKM or FFKM. The medium oil bladder 4 is connected with the oil-filled cavity 16 through the medium oil bladder adapter 19 to form an isobaric compensation system that changes with the external sea pressure. The cabin-plated gold copper needle 13 is sealed and fixed by epoxy resin to ensure the electrical insulation and sealing reliability under high pressure.

[0072] 5. Assembly and maintenance

[0073] 1) Pre-install the volt-ampere measurement unit 15 in the volt-ampere measurement unit quick-mounting position of the oil-filled cavity 16;

[0074] 2) Arrange and lock the peek inverted taper joint 26 and the hose hard pipe butt joint 27 to complete the sample pipeline connection;

[0075] 3) Connect the lead wires of the three electrodes (working electrode 28, reference electrode 29, and auxiliary electrode 30) with the shielded wires led out from the cabin-plated gold copper needle 13 through the limiting hole of the first shielding cover 17;

[0076] 4) Install the oil-filled cavity end cover 18 and confirm that the medium oil bladder 4 is in smooth communication with the medium oil bladder adapter 19;

[0077] 5) Connect the first connecting end cover 12 with the second connecting end cover 31 on the pressure-resistant control cavity 2 to complete the final assembly, and connect with the watertight connector 1 to perform communication self-checking.

[0078] When the volt-ampere measurement unit 15 needs to be replaced, make the volt-ampere measurement unit quick-mounting position opening upward, unlock the four external bolts, remove the volt-ampere measurement unit 15 and replace it with the same specification component. The delivery pipeline will not be contaminated during the replacement process. During this process, the oil-filled cavity 3 does not need to be emptied of silicone oil, and the medium oil bladder 4 remains connected with the medium oil bladder adapter 19 to achieve rapid recovery. After replacement, reset in the above order and perform sealing and electrical performance review.

[0079] 6. Work flow

[0080] After power on, the control circuit board 9 reads the thermocouple 6 and internal pressure signal to complete self-checking and temperature / pressure compensation setting; and controls the two-position three-way electromagnetic valve 23 to switch to the set measurement channel, and opens the peristaltic pump 21 to send the sample through the multi-stage filter head 14 into the voltammetry measurement cell 25 at 2 mL / min; after reaching the set volume and residence time, the enrichment, standing and scanning sequence (such as DPASV / SWV / LSV) is executed, and the three-electrode (working electrode 28, reference electrode 29 and auxiliary electrode 30) current / potential data is collected; after the measurement is completed, the next cycle or standby is entered. During the whole process, the continuous and single-point grounding of the first shield 17 and the shielding of the shell ensures the anti-interference ability of the high-impedance micro-current signal. As shown in Figure 6 The three measurement results of the same seawater sample by the underwater in-situ voltammetry analyzer with the full shielding structure supporting quick installation and removal of the measurement unit are basically the same, and the replacement of the voltammetry measurement unit 15 by the quick installation position has little effect on the measurement results, and the device has good test stability.

[0081] 7. Material and parameter optimization

[0082] The shell material is preferably titanium alloy; the electrode support and fluid joint are preferably PEEK; the sealing element is preferably FKM / FFKM; the conveying pipeline material is preferably PTFE / FEP; the electromagnetic valve is a high oil pressure resistant two-position three-way valve; and the peristaltic pump 21 hose is made of a low-outgassing and anti-swelling material. The roughness of each mating surface is preferably Ra≤1.6 μm to ensure the sealing performance. It should be noted that the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device.

[0083] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A fully shielded in-situ voltammetry analyzer for seawater under water, which supports quick mounting and dismounting of a measuring unit, characterized in that, The application relates to a kind of oil-filled cabin, medium oil skin bag, voltammetry unit and pressure-resistant control cabin. The oil-filled cabin is provided with a sampling unit and a first shield in the oil-filled cabin, the sampling unit includes a multi-stage filter head, a peristaltic pump, an electromagnetic valve and a conveying pipeline, the multi-stage filter head is opened on the outer wall of the oil-filled cabin, one end of the conveying pipeline is communicated with the multi-stage filter head, the other end is communicated with the voltammetry unit, the peristaltic pump and the electromagnetic valve are arranged on the conveying pipeline, the first shield covers the inner wall of the oil-filled cabin, and the voltammetry unit quick mounting position is arranged on the side wall of the oil-filled cabin. The medium oil skin bag is fixedly communicated with the oil-filled cabin, and the oil-filled cabin and the medium oil skin bag are filled with medium oil. The voltammetry unit is installed in the voltammetry unit quick mounting position and used for voltammetry measurement of the sample to be measured. The pressure-resistant control cabin is fixedly connected with the oil-filled cabin, and a cabin-plunging gold-plated copper needle is arranged at the fixed connection position, the pressure-resistant control cabin is provided with an energy storage battery pack and a control circuit board. The voltammetry unit is connected with one end of the cabin-plunging gold-plated copper needle through a shielded wire, the other end of the cabin-plunging gold-plated copper needle is connected with the control circuit board through a shielded wire, and data transmission is realized. The voltammetry unit includes a voltammetry cell, a peek inverted taper joint, a soft tube and hard tube butt joint, a working electrode, a reference electrode and an auxiliary electrode. The voltammetry cell is divided into a sample flow region and a pressure balance oil seal region, the sample flow region is used for flow, enrichment and voltammetry measurement of the sample to be measured, the pressure balance oil seal region is communicated with the oil-filled cavity to realize pressure compensation and provide an electrical insulation environment. The sensing ends of the working electrode, the reference electrode and the auxiliary electrode are arranged in the sample flow region, the electrical connection ends are arranged in the pressure balance oil seal region, and an O-shaped sealing ring is arranged between the two regions. The peek inverted taper joint is communicated with the sample flow region of the voltammetry cell, one end of the soft tube and hard tube butt joint is communicated with the peek inverted taper joint, and the other end is communicated with the conveying pipeline. The pressure-resistant control cabin is further provided with a watertight connector and a thermocouple. The watertight connector is connected with the control circuit board and used for external communication and synchronous control. The other end of the cabin-plunging gold-plated copper needle is connected with the control circuit board through a shielded wire, specifically connected with an electrode signal receiving end of the control circuit board, and the electrode signal receiving end is covered by a second shield to form an electromagnetic shield. The thermocouple is used for environment temperature monitoring and voltammetry temperature compensation. The oil-filled cabin includes an oil-filled cavity, an oil-filled cavity end cover and a first connection end cover arranged at two ends of the oil-filled cavity, the multi-stage filter head is arranged on the oil-filled cavity end cover, and the voltammetry unit quick mounting position is arranged on the oil-filled cavity. The pressure-resistant control cabin includes a pressure-resistant control cavity, a second connection end cover and a temperature measurement end cover arranged at two ends of the pressure-resistant control cavity, and the watertight connector and the thermocouple are arranged on the temperature measurement end cover. The first connection end cover is fixedly connected with the second connection end cover through threads, and the oil-filled cabin and the pressure-resistant control cabin are connected. ​ 2. The underwater amperometric analyzer in situ according to claim 1, characterized by the fact that, The voltammetry measuring unit is connected with the quick mounting position of the voltammetry measuring unit by bolts, and an O-shaped sealing ring is arranged at the contact position between the voltammetry measuring unit and the oil-filled cabin body.

3. The underwater amperometric analyzer of claim 1, wherein, The peristaltic pump adopts an in-pipe flow structure, so that the sample to be measured only contacts the inner surface of the conveying pipeline.

4. The underwater amperometric analyzer of claim 1, wherein, The medium oil is silicon oil, the material of the conveying pipeline is PTFE or FEP material, and the through-cabin gold-plated copper needle is sealed and held by epoxy resin.

5. A measurement method using the full-shielded structure in-situ voltammetric analyzer with the support measurement unit quick mounting and dismounting according to any one of claims 1-4, characterized in that, The method comprises the following steps: 1) preinstall the voltammetry measuring unit in the quick mounting position of the voltammetry measuring unit, and place the underwater in-situ voltammetry analyzer in the test water body; 2) control the circuit board to read the thermocouple to complete self-checking and temperature compensation setting; control the electromagnetic valve to open the conveying pipeline, start the peristaltic pump, draw the sample to be measured from the test water body, and send the sample to the voltammetry measuring pool through the multi-stage filter head; after the set volume and residence time are reached, execute the enrichment, standing and scanning sequence, collect the current / potential data of the working electrode, the reference electrode and the auxiliary electrode to the control circuit board, and transmit the measurement data back to the computer through the water-tight connector; after the measurement is completed, enter the next cycle of measurement or standby.

6. The method of claim 5, wherein, When the voltammetry measuring unit needs to be replaced, make the opening of the quick mounting position of the voltammetry measuring unit face upward, dismount the voltammetry measuring unit and replace it with a new one.

Images