In-situ deep sea carbon dioxide partial pressure measuring system

Abstract

The invention belongs to the technical field of seawater measurement, and relates to an in-situ deep sea carbon dioxide partial pressure measurement system, which comprises a high-pressure-resistant shell in which a chamber is formed, and a detection system is arranged in the chamber; the invention discloses a four-in-one electromagnetic valve terminal. A double-cylinder filter; a seawater spraying balance system; an air cavity is formed between the balance membrane and the bottom of the high-pressure-resistant shell, in order to increase the size of the CO2 air cavity, the air cavity is designed to be an S-shaped channel to cover the whole balance membrane, the larger the contact area of the air cavity and the balance membrane is, CO2 in seawater can enter the air cavity more easily, however, the smaller the supporting face is, the smaller the balance membrane is, sealing of the balance membrane is not facilitated, and therefore design of a balance membrane sealing structure needs to be carried out. And under the premise of ensuring that the volume of the air cavity is large enough as much as possible, underwater high-pressure sealing is realized. The system provided by the invention can realize long-term in-situ carbon dioxide partial pressure observation of atmosphere or seawater by utilizing gas diffusion and dynamic balance principles.

Description

Technical Field

[0001] The present invention belongs to the technical field of seawater measurement and relates to an in-situ deep-sea carbon dioxide partial pressure measurement system. Background Art

[0002] The ocean plays a crucial role in the global carbon cycle, especially in the processes of absorbing and releasing atmospheric carbon dioxide (CO2), which has a profound impact on climate change and ocean acidification. Therefore, accurately measuring the partial pressure of dissolved CO2 in seawater ( p pCO2) is of great significance for studying ocean carbon fluxes, evaluating carbon sink capabilities, and predicting future climate change.

[0003] Currently, the measurement of pCO2 mainly relies on laboratory analysis, shipboard observations, or buoy sensors. However, traditional measurement methods have the following problems: laboratory analysis requires manual collection of seawater samples and bringing them back to the laboratory for gas chromatography or electrochemical analysis, which is a complex process and difficult to achieve real-time and long-term monitoring; shipboard observations rely on research ships to conduct regular cruises for measurement, with limited spatial coverage and high long-term observation costs; buoy or sensor mainly uses optical or electrochemical detection technologies, although they can conduct long-term monitoring, their stability, anti-pollution ability, and long-term accuracy in the deep-sea high-pressure environment still need to be improved.

[0004] To address these problems, in recent years, in-situ pCO2 measurement technologies based on the principles of gas diffusion and dynamic equilibrium have been gradually developed. The partial pressure equilibrium of CO2 is achieved through a balance membrane or a gas-liquid exchanger, and combined with optical or electrochemical sensors for detection. This method reduces the dependence on chemical reagents, improves the degree of automation, and has the potential for long-term observation. However, in the deep-sea environment, affected by high pressure, low temperature, and the complexity of seawater components, existing systems still face many challenges in terms of high-pressure resistance sealing, long-term stability, anti-pollution ability, and response time. Therefore, there is an urgent need for an in-situ pCO2 measurement system that can adapt to the deep-sea environment, has good sealing performance and long-term stability, to support global ocean carbon cycle research and climate change prediction. Summary of the Invention

[0005] The present invention provides an in-situ carbon dioxide partial pressure measurement system applicable to atmospheric and oceanic environments, aiming to improve the accuracy, long-term stability, and anti-pollution ability of CO2 measurement to meet the needs of ocean carbon cycle research and climate change monitoring.

[0006] To achieve the above-mentioned invention object, the present invention adopts the following technical solutions: An in-situ deep-sea carbon dioxide partial pressure measurement system, comprising: a high-pressure-resistant housing, a chamber is formed inside the high-pressure-resistant housing, and a detection system, a four-in-one solenoid valve island, a seawater spray balance system and a double-barrel filter are arranged in the chamber; the detection system includes a non-dispersive infrared absorption spectrometer detector, a humidity sensor and a temperature / pressure sensor; the four-in-one solenoid valve island is composed of four two-position three-way solenoid valves, a raft plate and a substrate, wherein, a groove is formed between the raft plate and the substrate; the four two-position three-way solenoid valves are fixed inside the four-in-one solenoid valve island, and are respectively the 1st solenoid valve, the 2nd solenoid valve, the 3rd solenoid valve and the 4th solenoid valve; the seawater spray balance system is composed of a CO2 balance membrane, a flow-through cell and a submersible pump; an air cavity is formed between the top surface of the CO2 balance membrane and the bottom of the high-pressure-resistant housing.

[0007] Preferably, the zero calibration and gas calibration functions of the detection system are realized by switching the gating of different ports of the 1st solenoid valve, the 2nd solenoid valve, the 3rd solenoid valve and the 4th solenoid valve. Specifically: for the 1st solenoid valve, the third port of the 1st solenoid valve is connected to the air cavity; for the 2nd solenoid valve, the third port of the 2nd solenoid valve is connected to the second port of the 1st solenoid valve through the groove between the raft plate and the substrate, the first port of the 2nd solenoid valve is connected to the calibration gas - calibration gas path of the detection system, and the second port of the 2nd solenoid valve is connected to the detection system through a brushless air pump and a double-barrel filter; for the 3rd solenoid valve, the first port of the 3rd solenoid valve is connected to the calibration gas - calibration gas path of the detection system, and the second port of the 3rd solenoid valve is connected to the detection system through a temperature sensor; and for the 4th solenoid valve, the third port of the 4th solenoid valve is connected to the air cavity, and the second port of the 4th solenoid valve is connected to the third port of the 3rd solenoid valve through the groove between the raft plate and the substrate; when the second port and the third port of the 1st solenoid valve are switched to be conducting, the second port and the third port of the 2nd solenoid valve are switched to be conducting, the second port and the third port of the 3rd solenoid valve are switched to be conducting, and the second port and the third port of the 4th solenoid valve are switched to be conducting, the detection path between the air cavity and the chamber is conducting; when the first port and the second port of the 2nd solenoid valve are switched to be conducting, and the first port and the second port of the 3rd solenoid valve are switched to be conducting, the calibration gas path of the detection system is conducting; when the first port and the second port of the 1st solenoid valve are switched to be conducting, the second port and the third port of the 2nd solenoid valve are switched to be conducting, the second port and the third port of the 3rd solenoid valve are switched to be conducting, and the first port and the second port of the 4th solenoid valve are switched to be conducting, the zero calibration path of the detection system is conducting.

[0008] Preferably, twelve round holes are provided on the substrate of the four-in-one solenoid valve island; a rectangular groove is designed on the joint surface of the raft plate and the substrate; the rectangular groove communicates with the round holes.

[0009] Preferably, desiccants and CO2 absorbents are respectively filled inside the double-barrel filter. The desiccant barrel of the double-barrel filter is connected to the second port of the second solenoid valve through a brushless air pump and is connected to the detection system through a filter membrane. The CO2 absorbent barrel of the double-barrel filter is respectively connected to the first port of the first solenoid valve and the first port of the fourth solenoid valve.

[0010] Preferably, the desiccant barrel of the double-barrel filter is configured to absorb water vapor in the detection path, zero calibration path, and calibration gas path. The filter membrane is configured to absorb fine particulate matter in the detection path, zero calibration path, and calibration gas path to prevent it from contaminating the detection system. The desiccant barrel and the CO2 absorbent barrel are designed as an integrated sealed structure.

[0011] Preferably, the detection system is embedded in a thermal insulation module, which is integrally machined from a high molecular polymer polyoxymethylene, and an EVA foam adhesive is pasted on the inner wall.

[0012] Preferably, the CO2 balance membrane is a mixed matrix membrane formed by inorganic fillers and a polymer matrix.

[0013] Preferably, the gas cavity is designed as an S-shaped channel to cover the entire balance membrane.

[0014] Preferably, a single O-ring sealing structure is adopted between the CO2 balance membrane and the pressure-resistant balance membrane housing.

[0015] Compared with the prior art, the core innovation points of the present invention are as follows: adopting an S-shaped channel gas cavity design to improve the balance efficiency, and at the same time optimizing the sealing structure to adapt to the deep-sea high-pressure environment; through non-dispersive infrared absorption spectroscopy detection, combined with temperature, humidity, and pressure compensation, improving the accuracy and long-term stability of CO2 measurement; combining a seawater spray balance system to achieve long-term in-situ CO2 partial pressure monitoring in the deep-sea environment, meeting the needs of ocean carbon cycle research and climate change monitoring. The in-situ deep-sea carbon dioxide partial pressure measurement system provided by the present invention can realize long-term in-situ carbon dioxide partial pressure observation of the atmosphere or seawater, is suitable for in-situ measurement of buoys and stations, and can be widely applied to fields such as ocean science research, climate change monitoring, and environmental assessment. Description of the Drawings

[0016] Figure 1 It is a schematic internal connection diagram of the in-situ deep-sea carbon dioxide partial pressure measurement system provided by the present invention; Figure 2 It is a schematic diagram of the four-in-one solenoid valve island structure provided by the present invention; Figure 3 It is a schematic diagram of the integrated sealed structure of the desiccant barrel and the CO2 absorbent barrel of the double-barrel filter provided by the present invention; Figure 4 Schematic diagram of the S-shaped channel at the bottom of the high-pressure resistant housing provided by the present invention; Figure 5 Schematic diagram of the installation position of the four-in-one solenoid valve island in the in-situ deep-sea carbon dioxide partial pressure measurement system provided by the present invention; Figure 6 Connection schematic diagram of the four-in-one solenoid valve island in the in-situ deep-sea carbon dioxide partial pressure measurement system provided by the present invention. Detailed implementation manners

[0017] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0018] The embodiments of the present invention are described in detail below. Examples of the specific implementation manners are shown in the accompanying drawings, in which the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation to the present invention.

[0019] The present invention provides an in-situ carbon dioxide partial pressure measurement system applicable to atmospheric and deep-sea environments, aiming to improve the accuracy, long-term stability and anti-pollution ability of CO2 measurement to meet the needs of ocean carbon cycle research and climate change monitoring. As Figure 1 shown, the in-situ deep-sea carbon dioxide partial pressure measurement system can be applied to in-situ carbon dioxide partial pressure measurement in the atmosphere-deep sea. From the perspective of the external mechanical structure composition, the carbon dioxide partial pressure measurement system includes main components such as a high-pressure resistant housing 26, an upper cover 4, a lower cover 21, a flow-through cell 25, a submersible pump 16 and a CO2 equilibrium membrane 22. Among them, the high-pressure resistant housing 26 is preferably made of TC4 titanium alloy, which reduces the weight while having good pressure resistance. A chamber 27 is formed inside the high-pressure resistant housing 26, and a detection system is arranged in the chamber 27. The specific structure and function of the detection system will be described in detail below. A flow-through cell 25 is arranged at the bottom of the high-pressure resistant housing 26. The flow-through cell 25 and the CO2 equilibrium membrane 22 are combined with the submersible pump 16 to form a seawater spray equilibrium system. More specifically, the seawater spray equilibrium system is configured to spray seawater on the CO2 equilibrium membrane 22 with the submersible pump. The CO2 equilibrium membrane 22 selectively permeates the CO2 gas in seawater. Similarly, the CO2 equilibrium membrane 22 can also selectively permeate the CO2 gas in the atmosphere. The CO2 equilibrium membrane 22 is a high-pressure resistant mixed matrix membrane formed by inorganic fillers and a polymer matrix. An air chamber 28 is formed in the S-shaped channel at the bottom of the upper cover 4 and the CO2 equilibrium membrane 22 at the top of the CO2 equilibrium membrane 22, and the air chamber 28 is used for the gas passing through the CO2 equilibrium membrane 22.

[0020] As Figure 1The in-situ carbon dioxide partial pressure measurement system shown selectively gates the detection path, the zero calibration path, and the calibration gas path. The detection path is connected by a gas path between the gas chamber 28 and the chamber 27, and is configured such that CO2 gas enters the detection system through the gas path connecting the gas chamber 28 and the chamber 27 to achieve the detection of the carbon dioxide partial pressure of the atmosphere and seawater; the zero calibration path and the calibration gas path are arranged in the chamber 27, and the conversion of the zero calibration path and the calibration gas path is achieved by configuring and switching the gating of different ports of the first solenoid valve, the second solenoid valve, the third solenoid valve, and the fourth solenoid valve. The detection system at least includes: a non-dispersive infrared absorption spectrometer 5, a temperature and humidity sensor 8, and a pressure sensor 18. Combining the temperature and humidity data of the temperature and humidity sensor 8 and the pressure compensation of the pressure sensor 18 can improve the accuracy and long-term stability of CO2 measurement. The in-situ deep-sea carbon dioxide partial pressure measurement system provided by the present invention can achieve long-term in-situ observation of the carbon dioxide partial pressure of the atmosphere and seawater, and is suitable for in-situ measurement of buoys and stations.

[0021] In a preferred embodiment, the CO2 equilibrium membrane 22 is a high-pressure-resistant mixed matrix membrane formed by inorganic fillers and a polymer matrix. A gas chamber 28 is formed between the bottom S-shaped channel of the lower cover 21 of the high-pressure-resistant housing 26 and the top of the CO2 equilibrium membrane 22. When the detection path is gated for measurement, the carbon dioxide gas in the gas chamber 28 is continuously balanced with the carbon dioxide dissolved in the atmosphere or seawater outside the gas chamber 28. After reaching dynamic equilibrium, the carbon dioxide gas enters the detection system through the gas path for detection and measurement. The gas chamber 28 is designed as an S-shaped reciprocating channel to accelerate the diffusion of carbon dioxide passing through the equilibrium membrane into the gas flow path, as Figure 4 shown.

[0022] In some embodiments of the present invention, the submersible pump 16 is installed and fixed on the side wall of the flow cell 25, with the water outlet and the water inlet arranged vertically up and down, and the cross-sectional area of the water outlet is designed to be half of the cross-sectional area of the water inlet, further increasing the pressure of the submersible pump spraying on the CO2 equilibrium membrane and improving the equilibrium efficiency. By continuously spraying pressurized seawater on the surface of the equilibrium membrane, the pressurized seawater can accelerate the equilibrium speed of carbon dioxide on both sides of the CO2 equilibrium membrane 22.

[0023] The gating and switching of the detection path, the zero calibration path, and the calibration gas path are described in detail below, as Figure 1As shown, it is achieved by switching the gating of different ports of the first solenoid valve 19, the second solenoid valve 15, the third solenoid valve 10, and the fourth solenoid valve 12. The third port of the first solenoid valve 19 is connected to the air chamber 28. The third port of the second solenoid valve 15 is connected to the second port of the first solenoid valve 19 through the groove in the middle of the raft 17 and the substrate 14. The first port of the second solenoid valve 15 is connected to the standard gas - standard gas passage of the detection system. The second port of the second solenoid valve 15 is connected to the detection system through the brushless air pump 13, the desiccant cylinder 9 of the double - tube filter, and the filter membrane 7. The first port of the third solenoid valve 10 is connected to the standard gas - standard gas passage of the detection system. The second port of the third solenoid valve 10 is connected to the detection system through the temperature and humidity sensor 8. The third port of the fourth solenoid valve 12 is connected to the air chamber 28. The second port of the fourth solenoid valve 12 is connected to the third port of the third solenoid valve 10 through the groove in the middle of the raft 17 and the substrate 14. When the second port and the third port of the first solenoid valve 19 are switched on, the second port and the third port of the second solenoid valve 15 are switched on, the second port and the third port of the third solenoid valve 10 are switched on, and the second port and the third port of the fourth solenoid valve 12 are switched on, the detection passage between the air chamber 28 and the chamber 27 is conducted. When the first port and the second port of the second solenoid valve 15 are switched on, and the first port and the second port of the third solenoid valve 10 are switched on, the standard gas passage of the detection system is conducted. When the first port and the second port of the first solenoid valve 19 are switched on, the second port and the third port of the second solenoid valve 15 are switched on, the second port and the third port of the third solenoid valve 10 are switched on, and the first port and the second port of the fourth solenoid valve 12 are switched on, the zero - calibration passage of the detection system is conducted. The gas flow paths between the components in the chamber 27 are connected through sealed silicone rubber tubes.

[0024] In some embodiments of the present invention, the first solenoid valve 19, the second solenoid valve 15, the third solenoid valve 10, and the fourth solenoid valve 12 are fixed to the four - way integrated solenoid valve island 29. The installation position and connection relationship of the four - way integrated solenoid valve island are as Figure 5 and 6 shown. The structure of the four - way integrated solenoid valve island 29 is as Figure 2 shown, including a raft 17 and a substrate 14. The raft and the substrate are made of PMMA material. The joint surface between the substrate and the raft is designed with a rectangular groove, and there are twelve round holes on the substrate; the rectangular groove is communicated with the round holes. The two are bonded into an integrated structure with shadowless glue and cured by ultraviolet light irradiation to form a sealed airtight passage to replace the complex interlaced air paths. The first solenoid valve 19, the second solenoid valve 15, the third solenoid valve 10, and the fourth solenoid valve 12 are connected to the four - way integrated solenoid valve island according to the positions shown in the figure.

[0025] In some embodiments of the present invention, as Figure 1The in-situ deep-sea carbon dioxide partial pressure measurement system shown can be automatically zeroed. A CO2 absorbent cartridge 11 is provided in chamber 27. The CO2 absorbent cartridge 11 is respectively connected to the first port of the first solenoid valve 19 and the first port of the fourth solenoid valve 12. When the first port and the second port of the first solenoid valve 19 are switched to conduct, the second port and the third port of the second solenoid valve 15 are switched to conduct, the second port and the third port of the third solenoid valve 10 are switched to conduct, and the first port and the second port of the fourth solenoid valve 12 are switched to conduct, the zeroing path between the detection system and the CO2 absorbent cartridge 11 is conducted. When the CO2 gas in the zeroing path is completely absorbed by the CO2 absorbent, the non-dispersive infrared absorption spectrometer 5 performs a zeroing operation. Soda lime granules can be preferably selected in the CO2 absorbent cartridge 11 to fully absorb the carbon dioxide residue in the zeroing path and turn the indicator purple.

[0026] In addition, the detection system further includes a temperature and humidity sensor 8, a desiccant cartridge 9, and a filter membrane 7. The temperature and humidity sensor 8 is configured to detect the temperature and humidity of the gas in the detection path, the zeroing path, and the calibration gas path. The desiccant cartridge 9 is configured to absorb the moisture of the gas in the detection path, the zeroing path, and the calibration gas path; anhydrous calcium chloride or other desiccants are installed in the desiccant cartridge 9 to reduce the moisture in the gas and improve the accuracy and long-term stability of CO2 measurement. The filter membrane 7 is configured to detect the fine particles in the detection path, the zeroing path, and the calibration gas path to prevent them from contaminating the detection system. In some embodiments of the present invention, the desiccant cartridge and the CO2 absorbent cartridge can adopt a split structure or can be designed as an integrated sealed structure to reduce the occupancy of the chamber space, as Figure 3 shown.

[0027] A brushless air pump 13 and a pressure sensor 18 are also configured in chamber 27. The brushless air pump 13 provides pressure for the air flow circulation in the detection path, the zeroing path, and the calibration gas path and adjusts the air flow rate. The pressure sensor 18 is configured to detect the pressure of the gas in the detection path and provide pressure compensation data for the non-dispersive infrared absorption spectrometer 5 to improve the accuracy of CO2 measurement.

[0028] In some embodiments of the present invention, the detection system preferably has a heating function and can maintain a constant temperature detection environment after setting a specific temperature. The heat preservation module is integrally machined from the high molecular polymer polyoxymethylene, and an EVA foam adhesive is pasted on the inner wall to maintain the detection system to detect under constant temperature conditions.

[0029] The following is the detection process for the carbon dioxide partial pressure in seawater.

[0030] As Figure 1The entire in-situ carbon dioxide partial pressure measurement system shown is placed in seawater. When the second port and the third port of the first solenoid valve 19 are switched to conduct, the second port and the third port of the second solenoid valve 15 are switched to conduct, the second port and the third port of the third solenoid valve 10 are switched to conduct, and the second port and the third port of the fourth solenoid valve 12 are switched to conduct, the detection path between the gas chamber 28 and the chamber 27 is conducted.

[0031] Start the brushless air pump 13. The CO2 gas in seawater continuously enters the gas chamber 28 through the CO2 equilibrium membrane, circulates in the detection path driven by the brushless air pump, and enters the detection system. At the same time, start the submersible pump 16. The flow cell is filled with pressurized seawater, and the seawater is sprayed on the bottom cavity 20 of the CO2 equilibrium membrane through the flow cell channel 24. The continuously flowing seawater can accelerate the equilibrium speed of CO2 on both sides of the CO2 equilibrium membrane. The CO2 in seawater and the gas in the gas chamber 28 are continuously balanced. After passing through the first solenoid valve 19, the second solenoid valve 15, the brushless air pump 13, the desiccant cartridge 9, the filter membrane 7, the non-dispersive infrared absorption spectrometer detector 5, the temperature and humidity sensor 8, the third solenoid valve 10, and the fourth solenoid valve 12 in sequence, it returns to the gas chamber 28 again. After further balancing, it enters the detection path to circulate again. Finally, the CO2 gas concentration in seawater and the CO2 gas in the gas chamber 28 reach dynamic equilibrium.

[0032] Start the non-dispersive infrared absorption spectrometer detector 5 and wait for it to preheat to the set temperature of 51.4 °C. The non-dispersive infrared absorption spectrometer detector 5 starts to detect under the condition of maintaining 51.4 °C.

[0033] The non-dispersive infrared absorption spectrometer detector 5 continuously measures the concentration of CO2 in the detection path. When the CO2 on both sides of the CO2 equilibrium membrane 22 is balanced, the measurement data of the non-dispersive infrared absorption spectrometer detector 5 is stable. After the measurement data is corrected by the temperature and humidity sensor 8 and the pressure sensor 18, the p CO2 in seawater is obtained, with the unit of ppm. The method of correcting the detection data of the non-dispersive infrared absorption spectrometer detector 5 by using the temperature and humidity sensor 8 and the pressure sensor 18 can adopt the methods in the prior art, which is not the focus of the present invention and will not be elaborated here.

[0034] After the detection system detects for a period of time, zero calibration is performed on the in-situ deep-sea carbon dioxide partial pressure measurement system to correct the zero drift that may occur after the long-term use of the sensor, resulting in inaccurate measurement data, ensure the measurement accuracy, and at the same time compensate for the environmental factors such as temperature and humidity that may affect the reference value of the sensor and reduce the interference of these factors on the measurement results. The zero calibration process refers to the specific introduction above and will not be elaborated here.

[0035] The detection process for the carbon dioxide partial pressure in the atmosphere is the same as the above detection process in seawater, except that the detection process for the carbon dioxide partial pressure in the atmosphere does not require starting the submersible pump.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, for those of ordinary skill in the art, it is still possible to modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions required to be protected by the present invention.

Claims

1. An in-situ deep-sea carbon dioxide partial pressure measurement system, characterized in that: include: A high-pressure resistant shell, wherein a chamber is formed in the high-pressure resistant shell, wherein a detection system, a four-position integrated solenoid valve island, a seawater spray balance system and a binocular filter are arranged in the chamber; the detection system comprises a non-dispersive infrared absorption spectrum detector, a humidity sensor and a temperature / pressure sensor; the four-position integrated solenoid valve island is composed of four two-position three-way solenoid valves, a raft and a base plate, wherein a groove is formed between the raft and the base plate; four two-position three-way solenoid valves are fixed in the four-position integrated solenoid valve island, namely the first solenoid valve, the second solenoid valve, the third solenoid valve and the fourth solenoid valve; the seawater spray balance system is composed of a CO2 balance membrane and a circulation pool in combination with a submersible pump; an air cavity is formed between the top surface of the CO2 balance membrane and the bottom of the high-pressure resistant shell.

2. The in-situ deep-sea carbon dioxide partial pressure measurement system according to claim 1, characterized in that: The zeroing and calibration gas functions of the detection system are realized by switching the selection of different ports of the first solenoid valve, the second solenoid valve, the third solenoid valve, and the fourth solenoid valve, specifically: the first solenoid valve, the third port of the first solenoid valve is connected to the air cavity; the second solenoid valve, the third port of the second solenoid valve is connected to the second port of the first solenoid valve through the groove between the raft and the substrate, the first port of the second solenoid valve is connected to the calibration gas-calibration gas passage of the detection system, and the second port of the second solenoid valve is connected to the detection system through a brushless air pump and a duplex filter; the third solenoid valve, the first port of the third solenoid valve is connected to the calibration gas-calibration gas passage of the detection system, and the second port of the third solenoid valve is connected to the detection system through a temperature sensor; and the fourth solenoid valve, the third port of the fourth solenoid valve is connected to the air cavity, and the second port of the fourth solenoid valve is connected to the detection system through the The groove between the raft and the substrate is connected to the third port of the third solenoid valve; when the second port and the third port of the first solenoid valve are switched and connected, the second port and the third port of the second solenoid valve are switched and connected, the second port and the third port of the third solenoid valve are switched and connected, and when the second port and the third port of the fourth solenoid valve are switched and connected, the detection path between the air cavity and the chamber is connected; when the first port and the second port of the second solenoid valve are switched and connected, and the first port and the second port of the third solenoid valve are switched and connected, the calibration gas path of the detection system is connected; when the first port and the second port of the first solenoid valve are switched and connected, the second port and the third port of the second solenoid valve are switched and connected, the second port and the third port of the third solenoid valve are switched and connected, and when the first port and the second port of the fourth solenoid valve are switched and connected, the zeroing path of the detection system is connected.

3. The in-situ deep-sea carbon dioxide partial pressure measurement system according to claim 2, characterized in that: The base plate of the four-position integrated solenoid valve island is provided with twelve circular holes; the joint surface between the raft plate and the base plate is designed with rectangular grooves; the rectangular grooves are communicated with the circular holes.

4. The in-situ deep-sea carbon dioxide partial pressure measurement system according to claim 2, characterized in that: The inside of the duplex filter is filled with desiccant and CO2 absorbent respectively. The desiccant cylinder of the duplex filter is connected to the second port of the second solenoid valve through a brushless air pump and is connected to the detection system through a filter membrane; the CO2 absorbent cylinder of the duplex filter is connected to the first port of the first solenoid valve and the first port of the fourth solenoid valve respectively.

5. The in-situ deep-sea carbon dioxide partial pressure measurement system according to claim 2 or 4, characterized in that: The desiccant cylinder of the double-cylinder filter is configured to absorb moisture in the detection passage, zeroing passage and calibration gas passage; the filter membrane is configured to absorb tiny particles in the detection passage, zeroing passage and calibration gas passage to prevent them from contaminating the detection system; the desiccant cylinder and the CO2 absorbent cylinder are designed as an integrated sealing structure.

6. The in-situ deep-sea carbon dioxide partial pressure measurement system according to claim 1, characterized in that: The detection system is embedded in the heat preservation module, and the heat preservation module is processed by a high molecular polymer polyoxymethylene integrated machine, and the inner wall is pasted with EVA foam glue.

7. The in-situ deep-sea carbon dioxide partial pressure measurement system according to claim 1, characterized in that: The CO2 balance membrane is a mixed matrix membrane formed by an inorganic filler and a polymer matrix.

8. The in-situ deep-sea carbon dioxide partial pressure measurement system according to claim 7, characterized in that: The air cavity is designed as an S-shaped channel to cover the entire balancing film.

9. The in-situ deep-sea carbon dioxide partial pressure measurement system according to claim 7, characterized in that: A single-pass O-ring sealing structure is used between the CO2 balance membrane and the pressure-resistant balance membrane cover.

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