Parallel steel wire inhaul cable negative pressure dehumidification and full length detection system and method

Abstract

The invention discloses a negative pressure dehumidification and full length detection system and method for a parallel steel wire inhaul cable, and the system comprises a cable body which is composed of a plurality of parallel steel wire bundles, and a functional steel wire is provided with two through long grooves in the axial direction; the air supply system is in sealed connection with the first end of the cable body and provides dry air or inert gas for the cable body; the negative pressure generation system comprises an air pipe laid in the first groove and a negative pressure generation device and is used for forming a negative pressure environment in the cable body; and the detection system comprises a fiber grating sensor and a data processing and control unit, the fiber grating sensor is laid in the second groove, monitored temperature and humidity data are transmitted to the data processing and control unit in real time, and the working states of the gas supply system and the negative pressure generation system are adjusted according to the monitored data. The original humidity gas is changed from passive extrusion into negative pressure active extraction, and the data processing and control unit receives the temperature and humidity data within the full-length range of the longitudinal line in the cable body and performs feedback adjustment, so that autonomous circulation operation is realized.

Description

Technical Field

[0001] The present invention relates to the field of bridge engineering, and more particularly to a system and method for negative pressure dehumidification and full-length detection of parallel steel wire cables. Background Art

[0002] The cable-stayed cable is an important load-bearing component of the cable-stayed bridge, and its durability directly affects the safety of the bridge structure. In addition to high strength, it must also have good fatigue resistance, durability and corrosion resistance. As one of the main types of cables, the parallel steel wire cable-stayed cable is generally composed of a steel wire bundle, an outer PE sheath, and anchor heads at both ends. There are currently two main protection methods for cables. One is the protection of the steel wire, which is to implement hot-dip galvanizing or epoxy material de-lamination process on the steel wire to prevent rust. The second is the protection of the entire cable body, which is to hot-extrude a high-density polyethylene (PE) sheath outside the steel wire bundle, relying on the PE material's good airtightness, watertightness, and UV resistance to achieve a protective effect.

[0003] Cables are primarily subject to corrosion through stress corrosion and electrochemical corrosion. When the protective system ages or fails, it can no longer effectively isolate media such as air and water vapor. Once these media enter the sheath, they form a water film on the steel wire surface, causing electrochemical corrosion. Over time, under the combined effects of stress and electrochemical corrosion, the corrosion becomes increasingly severe, potentially leading to wire breakage. Existing cable-stayed systems are unable to detect environmental conditions within the wire bundle, such as temperature, humidity, and wire stress and strain. They are also unable to adjust or alter the internal cable environment, making it impossible to accurately assess and intervene in the cable's condition, impacting the lifespan of the cable and bridge.

[0004] With technological advancements, the industry has developed some solutions for dehumidifying stayed cables. These primarily involve using positive pressure gas delivery to remove moisture from the cable, and monitoring the temperature and humidity of the incoming and outgoing gas to infer the cable's internal conditions. However, positive pressure inflation cannot guarantee that the gas will fill every void within the cable, and monitoring can only be performed at a limited number of points, such as the air inlet and outlet, to infer the cable's internal conditions, which does not represent the actual internal environment. Summary of the Invention

[0005] The purpose of the present invention is to provide a negative pressure dehumidification and full-length detection system and method for parallel steel wire cables, which changes the original humidity gas from passive extrusion to negative pressure active extraction, receives the temperature and humidity data of the entire length of the longitudinal line inside the cable body through a data processing and control unit, and performs feedback adjustment to achieve autonomous circulation operation.

[0006] The technical solution adopted by the present invention to solve this technical problem is to provide a parallel steel wire rope negative pressure dehumidification and full-length detection system, including:

[0007] The cable body is composed of a plurality of parallel steel wire bundles, wherein at least one functional steel wire is provided in the steel wire bundle, and the functional steel wire is provided with two continuous grooves along the axial direction;

[0008] an air supply system, disposed at the first end of the cable body and sealedly connected to the cable body, for providing dry air or inert gas to the interior of the cable body;

[0009] A negative pressure generating system, comprising an air pipe and a negative pressure generating device arranged in the first groove, for forming a negative pressure environment in the cable body;

[0010] The detection system includes a fiber grating sensor and a data processing and control unit. The fiber grating sensor is laid in the second groove to monitor the temperature and humidity data inside the cable body in real time. The data processing and control unit is communicatively connected with the fiber grating sensor, the air supply system and the negative pressure generation system, and dynamically adjusts the working status of the air supply system and the negative pressure generation system according to the temperature and humidity data.

[0011] Preferably, in the parallel steel wire rope negative pressure dehumidification and full-length detection system, a plurality of functional steel wires are arranged in the steel wire bundle, and each functional steel wire is evenly distributed along the circumference of the steel wire bundle. Among the plurality of functional steel wires, at least one functional steel wire is located at the geometric center of the steel wire bundle.

[0012] Preferably, the parallel steel cable negative pressure dehumidification and full-length detection system, the air supply system includes:

[0013] Gas generator, used to prepare dry air or inert gas;

[0014] The inlet of the gas storage tank is connected to the outlet of the gas generator, and the outlet of the gas storage tank is sealed and connected to the air pipe.

[0015] Preferably, the parallel steel cable negative pressure dehumidification and full-length detection system, the air supply system further includes:

[0016] a delivery pipe, one end of which is sealedly connected to the outlet of the gas storage tank and the other end of which is sealedly connected to the air pipe;

[0017] an electric control valve, arranged on the delivery pipe;

[0018] The valve controller is integrated into the electric control valve, communicates with the data processing and control unit, and adjusts the opening of the electric control valve according to the control instructions.

[0019] Preferably, in the parallel steel cable negative pressure dehumidification and full-length detection system, the negative pressure generating device is an exhaust device, and the exhaust device includes:

[0020] An air pump is provided at the second end of the cable body, and an inlet of the air pump is sealedly connected to the air pipe. When the air pump is in operation, the pressure at the inlet of the air pipe is lower than the internal pressure of the gas storage tank, so that the gas in the gas storage tank enters the air pipe;

[0021] The vacuum pump controller is integrated into the vacuum pump, communicates with the data processing and control unit, and adjusts the speed of the vacuum pump according to the control instructions;

[0022] The exhaust pipe is connected to the outlet of the vacuum pump.

[0023] Preferably, in the parallel steel cable negative pressure dehumidification and full-length detection system, the negative pressure generating device is an inflation device, and the inflation device includes:

[0024] an inflator, hermetically connected between the air supply system and the air pipe. When the inflator is in operation, the gas pressure at the air pipe outlet is greater than the gas pressure outside the cable body. Under the action of the pressure difference, the gas is forced to flow from the air pipe outlet to the outside of the cable body, thereby driving the gas inside the air pipe to be discharged. The inflator forms a high-speed airflow inside the cable body by increasing the inflation rate, and uses the pressure difference to create a negative pressure environment inside the cable body.

[0025] The inflator controller is integrated into the inflator, communicates with the data processing and control unit, and adjusts the speed of the inflator according to the control instructions.

[0026] Preferably, in the negative pressure dehumidification and full-length detection system for parallel steel wire cables, a hygrometer is provided at the air pipe near the second end of the cable body.

[0027] Preferably, in the parallel steel wire rope negative pressure dehumidification and full-length detection system, a plurality of through holes are spaced apart along the axial and circumferential directions on the wall of the trachea, and the opening rate of a single trachea is greater than 0.5%.

[0028] Preferably, in the parallel steel wire rope negative pressure dehumidification and full-length detection system, the cross-sections of the two grooves of the functional steel wire are both semicircular, the width of the first groove matches the outer diameter of the tracheal tube, and the width of the second groove matches the outer diameter of the fiber grating sensor.

[0029] The present invention further provides a method for negative pressure dehumidification of parallel steel wire cables using the negative pressure dehumidification and full-length detection system for parallel steel wire cables described above, comprising the following steps:

[0030] S1: The fiber Bragg grating sensor monitors the humidity inside the cable in real time. When the humidity inside the cable exceeds the set value, it is fed back to the data processing and control unit;

[0031] S2: Start the air supply system to provide dry inert gas to the cable body, and then start the negative pressure generating system, wherein the air supply flow rate of the air supply system is greater than the inflation rate or exhaust rate of the inflation device or the exhaust device;

[0032] S3: Monitor the humidity distribution along the entire length of the cable body in real time through fiber grating sensors, and transmit the monitored data to the data processing and control unit in real time;

[0033] S4: When the humidity in all areas within the entire length of the cable body remains stable within a relative humidity of 50% for more than 15 minutes, the dehumidification is determined to be complete.

[0034] The present invention has at least the following beneficial effects:

[0035] 1. The negative pressure dehumidification principle is used to replace the gas inside the cable body, so that the original humidity gas inside the cable body is actively extracted instead of passively squeezed out.

[0036] 2. This negative pressure dehumidification and supporting full-length detection system realizes the internal environment detection of the inclined cable body within the entire longitudinal length range, avoiding the inference and judgment of the internal environment status of the inclined cable within the entire longitudinal length range based on the measurement results of a limited number of measuring points such as the air inlet and outlet.

[0037] 3. The data processing and control system in this invention can perform feedback adjustment based on the monitoring results to achieve autonomous circulation operation.

[0038] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a cross-sectional layout diagram of a cable body in a parallel steel cable negative pressure dehumidification and full-length detection system of the present invention;

[0040] Figure 2 This is a cross-sectional arrangement diagram of the functional steel wires of the cable body in a parallel steel wire cable negative pressure dehumidification and full-length detection system of the present invention;

[0041] Figure 3 This is a schematic structural diagram of an air pipe in a parallel steel wire cable negative pressure dehumidification and full-length detection system of the present invention;

[0042] Figure 4 This is a layout diagram of the air extraction device in a parallel steel wire cable negative pressure dehumidification and full-length detection system of the present invention;

[0043] Figure 5 This is a layout diagram of the inflation device in a parallel steel wire cable negative pressure dehumidification and full-length detection system of the present invention;

[0044] Figure 6 Schematic diagram of the experimental operation of negative pressure dehumidification in a negative pressure dehumidification method of parallel steel wire ropes of the present invention;

[0045] Figure 7 This is the cable dehumidification diagram in the cable dehumidification flow field simulation calculation summary report;

[0046] Figure 8 This is the calculation model diagram of the flow field inside the cable for negative pressure dehumidification in the cable dehumidification flow field simulation calculation summary report;

[0047] Figure 9 This is the grid distribution diagram of the calculation model in the summary report of the cable dehumidification flow field simulation calculation;

[0048] Figure 10 This is a diagram showing the two-phase distribution of wet air and nitrogen in the cable dehumidification flow field simulation calculation summary report;

[0049] Figure 11 This is the calculation result diagram of the under-sealed ventilation environment in the summary report of the cable dehumidification flow field simulation calculation;

[0050] Figure 12 This is the calculation result diagram of the sealed ventilation environment in the cable dehumidification flow field simulation calculation summary report;

[0051] Figure 13 This is the calculation result diagram of the fully open ventilation environment in the cable dehumidification flow field simulation calculation summary report;

[0052] Figure 14 This is the calculation result diagram of the cable dehumidification flow field simulation calculation summary report with an inlet flow velocity of 2m / s;

[0053] Figure 15 This is the calculation result diagram of the cable dehumidification flow field simulation calculation summary report with an inlet air velocity of 20m / s;

[0054] Figure 16 The inlet air velocity in the cable dehumidification flow field simulation calculation summary report is 138m / s (inlet air flow 1m 3 / h) calculation result diagram;

[0055] Figure 17 This is the air volume fraction diagram with an inlet flow velocity of 2m / s in the cable dehumidification flow field simulation calculation summary report;

[0056] Figure 18 This is the air volume fraction diagram with an inlet flow velocity of 20m / s in the cable dehumidification flow field simulation calculation summary report;

[0057] Figure 19The inlet air velocity in the cable dehumidification flow field simulation calculation summary report is 138m / s (inlet air flow 1m 3 / h) of air volume fraction;

[0058] Figure 20 The gas exchange efficiency diagram for different inlet flow rates in the cable dehumidification flow field simulation calculation summary report;

[0059] Figure 21 This is the internal pressure cloud diagram of the model with an inlet flow velocity of 2m / s in the cable dehumidification flow field simulation calculation summary report;

[0060] Figure 22 This is the internal pressure cloud diagram of the model with an inlet air velocity of 20m / s in the cable dehumidification flow field simulation calculation summary report;

[0061] Figure 23 The inlet flow velocity is 138m / s (inlet flow rate 1m 3 / h) model internal pressure cloud diagram;

[0062] Figure 24 This is the calculation result diagram of the air pipe inner diameter of 1.6mm in the cable dehumidification flow field simulation calculation summary report;

[0063] Figure 25 This is the calculation result diagram of the air pipe inner diameter of 4mm in the cable dehumidification flow field simulation calculation summary report;

[0064] Figure 26 This is the air volume fraction diagram for an air tube with an inner diameter of 1.6 mm in the cable dehumidification flow field simulation calculation summary report;

[0065] Figure 27 This is the air volume fraction diagram for a 4mm inner diameter air tube in the cable dehumidification flow field simulation calculation summary report;

[0066] Figure 28 This is the gas exchange efficiency diagram for different air tube inner diameters in the cable dehumidification flow field simulation calculation summary report;

[0067] Figure 29 This is the internal pressure cloud diagram of the model with an air pipe inner diameter of 1.6mm in the cable dehumidification flow field simulation calculation summary report;

[0068] Figure 30 This is the internal pressure cloud diagram of the model with an inner diameter of 4mm for the air pipe in the cable dehumidification flow field simulation calculation summary report;

[0069] Figure 31 This is the calculation result diagram of the model length of 0.5m in the cable dehumidification flow field simulation calculation summary report;

[0070] Figure 32This is the calculation result diagram of the model length of 1m in the cable dehumidification flow field simulation calculation summary report;

[0071] Figure 33 This is the calculation result diagram of the model length of 5m in the cable dehumidification flow field simulation calculation summary report;

[0072] Figure 34 This is the air volume fraction diagram for a model length of 0.5m in the cable dehumidification flow field simulation calculation summary report;

[0073] Figure 35 This is the air volume fraction diagram for a model length of 1m in the cable dehumidification flow field simulation calculation summary report;

[0074] Figure 36 This is the air volume fraction diagram for a model length of 5m in the cable dehumidification flow field simulation calculation summary report;

[0075] Figure 37 Gas exchange efficiency diagram for different model lengths in the cable dehumidification flow field simulation calculation summary report;

[0076] Figure 38 This is the internal pressure cloud diagram of the model with a length of 0.5m in the cable dehumidification flow field simulation calculation summary report;

[0077] Figure 39 This is the internal pressure cloud diagram of the model with a length of 1m in the cable dehumidification flow field simulation calculation summary report;

[0078] Figure 40 This is the internal pressure cloud diagram of the model with a length of 5m in the cable dehumidification flow field simulation calculation summary report;

[0079] Figure 41 This is the calculation result diagram of the cable dehumidification flow field simulation calculation summary report with an opening spacing of 0.1m;

[0080] Figure 42 This is the calculation result diagram of the cable dehumidification flow field simulation calculation summary report with an opening spacing of 0.2m;

[0081] Figure 43 This is the calculation result diagram of the cable dehumidification flow field simulation calculation summary report with an opening spacing of 0.5m;

[0082] Figure 44 This is the air volume fraction ratio diagram for an opening spacing of 0.1m in the cable dehumidification flow field simulation calculation summary report;

[0083] Figure 45 This is the air volume fraction ratio diagram for an opening spacing of 0.2m in the cable dehumidification flow field simulation calculation summary report;

[0084] Figure 46 This is the air volume fraction ratio diagram for an opening spacing of 0.5m in the cable dehumidification flow field simulation calculation summary report;

[0085] Figure 47 This is a graph of gas exchange efficiency at different opening spacings in the cable dehumidification flow field simulation calculation summary report;

[0086] Figure 48 This is the internal pressure cloud diagram of the model with an opening spacing of 0.1m in the cable dehumidification flow field simulation calculation summary report;

[0087] Figure 49 This is the internal pressure cloud diagram of the model with an opening spacing of 0.2m in the cable dehumidification flow field simulation calculation summary report;

[0088] Figure 50 This is the internal pressure cloud diagram of the model with a hole spacing of 0.5m in the cable dehumidification flow field simulation calculation summary report;

[0089] Figure 51 This is the calculation result diagram of the exhaust condition in the cable dehumidification flow field simulation calculation summary report;

[0090] Figure 52 This is the calculation result diagram of the gas transmission condition in the cable dehumidification flow field simulation calculation summary report;

[0091] Figure 53 This is the air volume fraction ratio diagram of the exhaust condition in the cable dehumidification flow field simulation calculation summary report;

[0092] Figure 54 This is the air volume fraction ratio diagram of the gas transmission condition in the cable dehumidification flow field simulation calculation summary report;

[0093] Figure 55 This is the model internal pressure cloud diagram of the exhaust condition in the cable dehumidification flow field simulation calculation summary report;

[0094] Figure 56 This is the model internal pressure cloud diagram of the gas transmission condition in the cable dehumidification flow field simulation calculation summary report;

[0095] Explanation of the accompanying drawings: 1. Cable body, 11. Functional steel wire, 12. First groove, 13. Second groove, 14. First end of the cable body, 15. Second end of the cable body, 2. Air supply system, 21. Gas generator, 22. Gas storage tank, 23. Electric control valve, 24. Delivery pipe, 3. Negative pressure generating system, 31. Air pipe, 311. Through hole, 32. Exhaust device, 321. Exhaust pump, 322. Exhaust pipe, 33. Inflating device, 331. Inflator, 4. Detection system, 41. Fiber Bragg grating sensor, 42. Data processing and control unit, 5. Humidity meter. DETAILED DESCRIPTION

[0096] The present invention is described in detail and completely below with reference to the accompanying drawings. Those skilled in the art will be able to implement the present invention based on this description. Before describing the present invention with reference to the accompanying drawings, it should be noted that the technical solutions and technical features provided in various parts of the present invention, including those described below, may be combined with each other unless they conflict.

[0097] In addition, the embodiments of the present invention described below are generally only part of the embodiments of the present invention, rather than all of the embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making any creative efforts should fall within the scope of protection of the present invention.

[0098] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, and its specific implementation process is as follows:

[0099] like Figure 1-6 As shown, the present invention provides a parallel steel wire cable negative pressure dehumidification and full-length detection system, comprising:

[0100] The cable body 1 is composed of a plurality of parallel steel wire bundles, wherein at least one functional steel wire 11 is provided in the steel wire bundle. The functional steel wire 11 is provided with two through-length grooves along the axial direction, for laying the air pipe 31 and the fiber grating sensor 41 respectively.

[0101] An air supply system 2 is provided at the first end 14 of the cable body and is sealed with the cable body 1, and is used to provide dry air or inert gas to the interior of the cable body 1. The dry inert gas helps prevent rust and corrosion of the steel wire and prolongs the service life of the cable body 1.

[0102] The negative pressure generating system 3 includes an air pipe 31 and a negative pressure generating device arranged in the first groove 12, and is used to form a negative pressure environment in the cable body 1;

[0103] The detection system 4 includes a fiber grating sensor 41 and a data processing and control unit 42. The fiber grating sensor 41 is laid in the second groove 13 of the functional steel wire 11 to monitor the temperature and humidity data in the cable body 1 in real time. The data processing and control unit 42 is communicatively connected with the fiber grating sensor 41, the air supply system 2 and the negative pressure generating system 3. The data processing and control unit 42 dynamically adjusts the working status of the air supply system 2 and the negative pressure generating system 3 according to the preset temperature and humidity threshold range and the received temperature and humidity data.

[0104] Furthermore, in the parallel steel cable negative pressure dehumidification and full-length detection system, multiple functional steel wires 11 are arranged within the steel wire bundle, and each functional steel wire 11 is evenly distributed along the circumference of the steel wire bundle. An exhaust pipe 31 and a fiber optic Bragg grating sensor 41 are respectively laid in the two grooves of each functional steel wire 11, forming multiple sets of parallel exhaust and detection channels. Among the multiple functional steel wires 11, at least one functional steel wire 11 is located at the geometric center of the steel wire bundle. In this embodiment, a preferred solution is to configure each functional steel wire 11 with a set of air supply system 2 and negative pressure generation system 3.

[0105] Furthermore, the parallel steel cable negative pressure dehumidification and full-length detection system, the air supply system 2 includes:

[0106] A gas generator 21 for preparing dry air or inert gas;

[0107] The inlet of the gas storage tank 22 is connected to the outlet of the gas generator 21 , and the outlet of the gas storage tank 22 is sealedly connected to the gas pipe 31 .

[0108] Furthermore, the parallel steel wire rope negative pressure dehumidification and full-length detection system, the air supply system 2 also includes:

[0109] A delivery pipe 24, one end of which is sealedly connected to the outlet of the gas storage tank 22, and the other end of which is sealedly connected to the gas pipe 31;

[0110] The electric control valve 23 is provided on the delivery pipe 24;

[0111] The valve controller is integrated in the electric control valve 23 and is in communication with the data processing and control unit 42 to adjust the opening of the electric control valve 23 according to the control instructions.

[0112] Furthermore, in the parallel steel cable negative pressure dehumidification and full-length detection system, the negative pressure generating device is an exhaust device 32, and the exhaust device 32 includes:

[0113] An air pump 321 is provided at the second end 15 of the cable body. The inlet of the air pump 321 is sealedly connected to the air pipe 31. When the air pump 321 is in operation, the pressure at the inlet of the air pipe 31 is lower than the internal pressure of the gas storage tank 22, so that the gas in the gas storage tank 22 enters the air pipe 31.

[0114] The air pump controller is integrated into the air pump 321 and is in communication with the data processing and control unit 42 to adjust the speed of the air pump 321 according to the control instructions;

[0115] The exhaust pipe 322 is connected to the outlet of the air pump 321 .

[0116] Furthermore, in the parallel steel cable negative pressure dehumidification and full-length detection system, the negative pressure generating device is an inflation device 33, and the inflation device 33 and the air supply system 2 are located at the same end of the cable body. The inflation device 33 includes:

[0117] The inflator 331 is sealed and connected between the air supply system 2 and the air pipe 31. When the inflator 331 is in operation, the gas pressure at the outlet of the air pipe 31 is greater than the gas pressure outside the cable body 1. Under the action of the pressure difference, the gas is forced to flow from the outlet of the air pipe 31 to the outside of the cable body 1, thereby driving the gas inside the air pipe 31 to be discharged. The inflator 331 forms a high-speed airflow within the cable body 1 by increasing the inflation rate, and uses the pressure difference to create a negative pressure environment inside the cable body 1. In this embodiment, a high-speed flow of dry inert gas is injected. Based on the Bernoulli principle, a negative pressure is formed around the high-speed flow of gas. When the gas pressure inside the cable body 1 is higher than the high-speed flow of gas in the air pipe 31, the gas will flow into the pipeline through the through holes 311 opened around the air pipe 31, achieving gas replacement.

[0118] The inflator controller is integrated into the inflator 331 and is in communication with the data processing and control unit 42 to adjust the speed of the inflator 331 according to control instructions.

[0119] Furthermore, in the negative pressure dehumidification and full-length detection system for the parallel steel wire rope, a humidity meter 5 is provided at the air pipe 31 near the second end 15 of the rope body.

[0120] Furthermore, in the parallel steel cable negative pressure dehumidification and full-length detection system, the air tube 31 is provided with multiple through-holes 311 spaced axially and circumferentially. The porosity of a single air tube is greater than 0.5%, enabling gas communication between the gaps between the steel wire bundles and the air tube 31. In this embodiment, a preferred embodiment is to provide the through-holes 311 on the air tube 31 within the cable body 1, where it contacts the steel wire bundles.

[0121] Furthermore, in the parallel steel wire rope negative pressure dehumidification and full-length detection system, the cross-sections of the two grooves of the functional steel wire 11 are both semicircular, the width of the first groove 12 matches the outer diameter of the trachea 31, and the width of the second groove 13 matches the outer diameter of the fiber optic Bragg grating sensor 41, which can achieve precise positioning, facilitate installation and maintenance, and improve the vacuum / inflation efficiency and the measurement accuracy of the fiber optic Bragg grating sensor 41.

[0122] The present invention further provides a negative pressure dehumidification method for parallel steel wire cables using the above-mentioned negative pressure dehumidification and full-length detection system for parallel steel wire cables, comprising the following steps:

[0123] S1: The fiber Bragg grating sensor 41 monitors the humidity inside the cable body 1 in real time. When the humidity inside the cable body 1 exceeds the set value, it is fed back to the data processing and control unit 42;

[0124] S2: Start the air supply system 2 to provide dry inert gas to the cable body 1, and then start the negative pressure generating system 3, wherein the air supply flow rate of the air supply system 2 is greater than the inflation rate or the exhaust rate of the inflation device 33 or the exhaust device 32;

[0125] S3: The fiber Bragg grating sensor 41 is used to monitor the humidity distribution in the entire length of the cable body 1 in real time, and the monitored data is transmitted to the data processing and control unit 42 in real time;

[0126] S4: When the humidity in all areas along the entire length of cable body 1 remains stable within a relative humidity of 50% for more than 15 minutes, dehumidification is considered complete. At this point, data processing and control unit 42 controls negative pressure generating system 3 and air supply system 2 to enter a maintenance state, maintaining a slightly negative pressure and a stable dry air environment within cable body 1 to prevent further moisture intrusion.

[0127] like Figure 6 As shown, the present invention also provides an experiment of a negative pressure dehumidification method simulating parallel steel wire cables, which is as follows:

[0128] 1. Experimental setup

[0129] Acrylic tubes were used to simulate the stay cables, with an outer diameter of 80 mm, an inner diameter of 75 mm, and a length of 6 m. The experimental air tubes had an outer diameter of 8 mm and an inner diameter of 5.5 mm. Humidity conditions were set in three acrylic tubes, with measuring point 1 at a distance of 0.89 m from the humidification hole, measuring point 2 at a distance of 2.90 m from the humidification hole, and measuring point 3 at a distance of 5.80 m from the humidification hole. The acrylic tubes were used to simulate the stay cables being freely closed, with the corresponding air pressure at 0.1 MPa (100 kPa). Dry gas at 5 kPa, 10 kPa, and 15 kPa was filled in the tubes, respectively. The specific parameter settings are shown in Table 1 below:

[0130] Table 1:

[0131]

[0132]

[0133] 2. Experimental Results

[0134] As shown in Table 2 below, under the same ventilation pressure and the same ventilation time, the dehumidification effect of different ventilation distances decreases as the distance increases.

[0135] Table 2

[0136]

[0137]

[0138] As shown in Table 3 below, at the same ventilation distance and ventilation pressure, the dehumidification effect increases with increasing ventilation time. At the same ventilation distance and ventilation time, the dehumidification effect increases with increasing ventilation pressure.

[0139] Table 3

[0140]

[0141] The present invention can control the opening of the electric control valve 23, the rotation speed of the air pump 321 and the rotation speed of the inflator 331 through the data processing and control unit 42, so as to adjust the dehumidification speed and thus improve the dehumidification effect.

[0142] 3. Data comparison with positive pressure dehumidification

[0143] Positive-pressure dehumidification involves filling the cable with high-pressure dry gas without a designated outlet. Instead, the cable's inherent sealing defects serve as the outlet. The amount and location of the outlet are uncertain and random, making quantitative data unavailable. However, due to the unfixed location of the outlet and the fact that some cables, despite the addition of positive-pressure dehumidification, still experience corrosion, qualitative analysis suggests that its dehumidification effectiveness is inferior to that of negative-pressure dehumidification.

[0144] like Figure 7-56 As shown, the present invention also provides a cable dehumidification flow field simulation calculation summary report, which is as follows:

[0145] 1. Calculation purpose

[0146] Cable dehumidification solutions such as Figure 7 As shown in the figure, the cable has an inner diameter of 70 mm and an outer diameter of 80 mm, and is sealed at both ends. The internal pressure of the cable is standard atmospheric pressure; the gas inside is humid air. Consider replacing one of the steel wires of the cable or strand with an air tube. The gas inside the air tube is dry air or nitrogen. Evenly spaced small holes are made in the air tube to connect it to the cable, and dry air or nitrogen is supplied to the air tube. The change in air pressure allows the gas inside the cable and the air tube to exchange, thus achieving the desired effect of dehumidifying the cable.

[0147] The purpose of this calculation is to explore the feasibility of the proposed built-in micro-porous air duct dehumidification and to "visualize" the air exchange flow in the duct.

[0148] 2. Calculation content

[0149] (1) Cable dehumidification simulation: Establish a flow field model inside the cable, determine the simulation grid type, size, boundary conditions and turbulence model, and use STAR-CCM+ software to simulate the gas exchange dehumidification inside the cable.

[0150] (2) Study on the influence of different structural parameters on gas exchange efficiency: The law of gas exchange and dehumidification under different ventilation environments, inlet flow rate, tracheal inner diameter, model length and opening spacing was explored, and the results were analyzed through volume distribution cloud map, volume ratio data and pressure cloud map results.

[0151] (3) Suggestions for optimizing cable dehumidification structure parameters: Taking into account the different working conditions of the flow field inside the cable, combined with the cable usage requirements and economic requirements, optimization suggestions for the cable's built-in micro-porous air duct dehumidification structure are given.

[0152] 3. Calculation conditions

[0153] 3.1 Computational Model

[0154] The flow field model inside the cable is established according to the above scheme description. Since the pipe and the opening can be regarded as symmetrical entities, in order to improve the calculation efficiency, the calculation model is only established in half of the area, and the openings are connected alternately up and down. Figure 8 shown.

[0155] In the STAR-CCM platform, the cut volume grid is used for mesh division. The key information of the grid is shown in Table 4. The grid is automatically encrypted in the pipeline inlet and outlet and opening areas. Figure 9 Shows the grid distribution.

[0156] Table 4 Model meshing parameters

[0157]

[0158]

[0159] The calculation boundary condition setting defines the left side of the air pipe as the velocity inlet, the right side as the pressure outlet, the symmetry plane of the model as the symmetry plane, and the remaining boundaries as the wall. The calculation adopts the k-ε turbulence model and the VOF Euler multiphase flow model, so that the phase volume fraction α i This variable is used to track the distribution of each phase in the region and the interface between the phases. The volume fraction of the phase in this calculation is defined as follows: when α = 0, the grid is wet air; when α = 1, the grid is nitrogen. Figure 10 shown.

[0160] 3.2 Calculation conditions

[0161] The key parameters of this calculation are as follows:

[0162] U——air intake velocity in the trachea, in m / s;

[0163] Dq——inner diameter of trachea, in mm, upper limit 5mm;

[0164] Dp——exhaust hole diameter, unit: mm;

[0165] n——number of exhaust holes, unit: “piece”;

[0166] H——the distance between exhaust holes, in cm;

[0167] L——Model length, in m.

[0168] Furthermore, in reality, the cable's outer surface isn't completely sealed. Setting it entirely as a wall boundary might result in inconsistent gas exchange. There are two practical application scenarios: HDPE-sheathed stay cables, which can be considered sealed; and suspension bridge strands, which can be considered less sealed. Therefore, we conducted research on different ventilation environments.

[0169] The final working condition setting is shown in Table 5 below:

[0170] Table 5 List of calculation conditions

[0171]

[0172]

[0173] 4. Calculation results

[0174] 4.1 Different ventilation environments

[0175] Since a less sealed environment is considered to have some connection with the outside air, a hole is added above the cable duct as a calculation model for a less sealed environment based on the sealed working condition model. The fully open environment is used as a comparison condition, and the air duct can be considered to be directly connected to the outside air. The calculation results of different ventilation environments are as follows Figure 11-13 As shown, they are under-sealed, sealed and fully open environments respectively.

[0176] The calculation results show that there is gas exchange between the moist air in the cable and the nitrogen in the trachea, indicating that the proposed dehumidification method using micro-perforated trachea built into the cable is feasible. The calculation results for the undersealed condition show that gas flows outward from the openings connected to the outside world, indicating that nitrogen in the trachea will escape through the openings into the cable during circulation, thereby squeezing the gas out of the cable from the connection points or other openings. The results for the sealed and undersealed environments are similar, while the phenomenon is not obvious in the fully open environment. This is because the gas escape from the trachea has a small impact on the external air pressure and does not cause gas squeezing.

[0177] 4.2 Different intake air flow rates

[0178] like Figure 14-16 The following table shows the calculation results of different intake air flow rates, which are 2m / s, 20m / s and 138m / s (intake air flow rate 1m 3 / h);

[0179] In order to quantitatively analyze the influence of different parameters on air exchange efficiency, the volume fraction of air inside the model is monitored. The slope of the curve can reflect the speed of decrease of the proportion of wet air inside the model and predict the time required for the humidity in the pipe to drop to a certain standard, which can be used as an indicator of gas exchange efficiency.

[0180] Different intake air flow rate data such as Figure 17-19 As shown, the intake air flow rate is 2m / s, 20m / s and 138m / s respectively (intake air flow rate 1m 3 / h).

[0181] The comparison of gas exchange efficiency is shown in Table 6. The time required for the humidity in the tube to drop to 50% is used as the comparison parameter to quantitatively compare the gas exchange efficiency of different inlet air flow rates.

[0182] Table 6 Comparison of the time required for humidity to drop to 50% under different working conditions

[0183]

[0184] Because the model length is relatively short under this operating condition, the slope represents only the rate of decrease in the proportion of moist air within the model during gas exchange. Data comparison shows that gas exchange efficiency significantly improves with increasing near-flow velocity. This means that increasing the tracheal ventilation velocity or increasing the intake air flow rate can effectively improve gas exchange efficiency within the model. The inflection point in the curve is due to the model initially being calculated entirely for air, with nitrogen delivered via the velocity inlet until, after the tracheal ventilation, only the gas exchange rate is measured.

[0185] The gas exchange efficiency (the time required for humidity to decrease by 50%) at different inlet air flow rates is as follows: Figure 20 As shown, the relationship is fitted as follows:

[0186] y=585.37x -0.706

[0187] In addition, the internal pressure cloud of the model is as follows Figure 21-23 As shown, the pressure comparison of different intake air flow rate models is shown in Table 7 below:

[0188] Table 7 Comparison of pressure of different intake air flow models

[0189]

[0190] The analysis shows that:

[0191] (1) Inside the model, the pressure at the inlet of the trachea is higher, and the pressure in the entire trachea gradually decreases. However, the pressure inside the cable is evenly distributed, and obvious pressure changes can be seen at the opening.

[0192] (2) As the intake air velocity increases, the pressure inside the pipe increases significantly.

[0193] 4.3 Different tracheal inner diameters

[0194] like Figures 24-25 The following table shows the calculation results of different tracheal inner diameters, which are 1.6 mm and 4 mm respectively;

[0195] like Figures 26-27 As shown, the air volume fraction ratios of different tracheal inner diameters are 1.6 mm and 4 mm respectively;

[0196] The comparison of gas exchange efficiency is shown in Table 8. The time required for the humidity in the tube to drop to 50% was used as the comparison parameter to quantitatively compare the gas exchange efficiency of different tracheal inner diameters.

[0197] Table 8 Comparison of the time required for humidity to drop to 50% under different working conditions

[0198]

[0199] The calculation results show that increasing the inner diameter of the trachea actually reduces its gas exchange efficiency. This is because the rate of nitrogen escape is more influenced by the intake velocity and the size of the exhaust hole. Increasing the inner diameter of the trachea does not improve gas exchange efficiency. On the contrary, increasing the diameter of the trachea allows nitrogen to flow smoothly forward, reducing the gas pressure inside the trachea and reducing the escape of nitrogen from the exhaust hole into the cable, which is detrimental to gas exchange.

[0200] Gas exchange efficiency (the time required for humidity to decrease by 50%) of different tracheal diameters is as follows Figure 28 As shown, the relationship is fitted as follows:

[0201] y=120x-128

[0202] The pressure cloud diagram inside the model is as follows Figures 29-30 The pressure comparison of different tracheal inner diameter models is shown in Table 9 below:

[0203] Table 9 Comparison of pressure of models with different tracheal inner diameters

[0204]

[0205] The analysis shows that:

[0206] (1) Inside the model, the pressure at the inlet of the trachea is higher, and the pressure in the entire trachea gradually decreases. However, the pressure inside the cable is evenly distributed, and obvious pressure changes can be seen at the opening.

[0207] (2) Increasing the inner diameter of the trachea can reduce the pressure at the inlet of the trachea

[0208] 4.4 Different model lengths

[0209] The calculation results of different model lengths are as follows Figures 31-33 As shown, the model lengths are 0.5m, 1m and 5m respectively. The air volume fractions at different model lengths are as follows: Figures 34-36 shown.

[0210] The comparison of gas exchange efficiency is shown in Table 10. The time required for the humidity in the tube to drop to 50% is used as the comparison parameter to quantitatively compare the gas exchange efficiency of different model lengths.

[0211] Table 10 Comparison of the time required for humidity to drop to 50% under different working conditions

[0212]

[0213] As the model length increases, gas exchange becomes more complex. When nitrogen flowing through the air tube reaches one opening, it escapes. Air in the cable is squeezed out and then discharged through all subsequent openings. This cycle repeats continuously, causing the gases to continuously mix. Therefore, with longer tubes, nitrogen continuously escapes from the openings as it is transported forward, while air entering from subsequent openings slows the nitrogen's forward movement.

[0214] Gas exchange efficiency (the time required for humidity to decrease by 50%) of different model lengths is as follows Figure 37 As shown, the relationship is fitted as follows:

[0215] y=-0.6239x 2 +10.476x-1.0819

[0216] The pressure cloud diagram inside the model is as follows Figures 38-40 The comparison of model pressures at different model lengths is shown in Table 11 below:

[0217] Table 11 Comparison of model pressures at different model lengths

[0218]

[0219] The analysis shows that:

[0220] (1) Regardless of the length of the pipeline, the pressure cloud pattern does not change. That is, the pressure at the inlet of the trachea is higher, and the pressure in the entire trachea gradually decreases. However, the pressure in the cable is evenly distributed, and obvious pressure changes can be seen at the opening.

[0221] (2) The increase in model length has little effect on pressure.

[0222] 4.5. Different opening spacing

[0223] The calculation results of different opening spacing are as follows Figures 41-43As shown, the opening spacing is 0.1m, 0.2m and 0.5m respectively. The air volume fraction at different opening spacings is as follows: Figures 44-46 As shown;

[0224] Table 12 compares gas exchange efficiency, using the predicted time required for humidity in the pipe to drop to 50% as the comparison parameter to quantitatively compare gas exchange efficiency at different opening spacings. However, unlike the previous operating conditions, this model is longer, and nitrogen has not yet flowed through the pipe. This parameter comparison was conducted while nitrogen was still being transported along the pipe, which is consistent with the actual situation of a long cable.

[0225] Table 12 Comparison of the time required for humidity to drop to 50% under different working conditions

[0226]

[0227]

[0228] From the results, it can be seen that the opening spacing has little effect on the gas exchange rate, but affects the nitrogen flow distance. The larger the opening spacing, the longer the nitrogen flows along the pipeline.

[0229] Gas exchange efficiency (time required for humidity to decrease by 50%) at different opening spacings is as follows Figure 47 As shown, the relationship is fitted as follows:

[0230] y=-5.8333x 2 -3.25x+36.083

[0231] The pressure cloud diagram inside the model is as follows Figures 48-50 The pressure comparison of models with different opening spacing is shown in Table 13 below:

[0232] Table 13 Comparison of pressure of models with different opening spacing

[0233]

[0234] The analysis shows that:

[0235] (1) As the opening spacing increases, the negative pressure at the pipeline outlet decreases significantly.

[0236] (2) The hole spacing has little effect on the inlet pressure

[0237] 4.6. Pumping conditions

[0238] The above conditions all simulate nitrogen delivery into the duct. This section simulates the situation where air is extracted from the cable at the right end of the duct, and the duct is automatically replenished with external nitrogen. The extraction velocity is 138 m / s (extraction flow rate 1 m³ / h). This is compared with the nitrogen delivery condition B3, which has an intake velocity of 138 m / s (extraction flow rate 1 m³ / h). Both conditions share the same duct inner diameter, model length, and opening spacing.

[0239] The calculation results of different working conditions are as follows Figures 51-52 As shown in Figure 2, they are respectively the gas extraction working condition and the gas transmission working condition. Figures 53-54 As shown in the figure, from the volume fraction calculation results, the gas flow conditions of the two are similar and the gas exchange efficiency is basically the same.

[0240] Pressure cloud diagram comparison Figures 55-56 As shown;

[0241] The data shows that the pressure at both ends of the pipeline varies between the gas transmission and extraction conditions. The extraction condition is generally negative, with a higher negative pressure at the extraction end. The gas transmission condition has a higher pressure at the delivery end. The pressure at a uniform location inside the cable is positive.

[0242] 5. Summary

[0243] This calculation explored the gas exchange and dehumidification behavior of cable-mounted micro-perforated trachea under various ventilation conditions, including airflow velocity, trachea inner diameter, model length, and hole spacing. The following conclusions were drawn:

[0244] (1) There is a gas exchange phenomenon between the nitrogen introduced into the trachea and the moist air in the cable, and the dehumidification scheme of the micro-trachea with holes built into the cable is feasible.

[0245] (2) Increasing the air flow rate into the trachea can effectively improve the gas exchange efficiency, and will also significantly increase the inlet pressure in the tube.

[0246] (3) Increasing the inner diameter of the trachea can reduce the inlet pressure, but this is detrimental to gas exchange. The size of the trachea inner diameter should be determined by considering the pressure bearing capacity of the pipeline and the inlet gas velocity of the trachea.

[0247] (4) As the length of the model increases, the gas exchange becomes more complex. The nitrogen in the trachea enters the cable through the exhaust hole, and the humid air in the cable is squeezed out. In this process, the gases are constantly mixed and the overall humidity continues to decrease.

[0248] (5) The opening spacing has little effect on the gas exchange rate, but affects the nitrogen flow distance. The larger the opening spacing, the longer the nitrogen flow distance along the pipeline.

[0249] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A parallel steel wire rope negative pressure dehumidification and full-length detection system, characterized in that: include: The cable body is composed of a plurality of parallel steel wire bundles, wherein at least one functional steel wire is provided in the steel wire bundle, and the functional steel wire is provided with two continuous grooves along the axial direction; an air supply system, disposed at the first end of the cable body and sealedly connected to the cable body, for providing dry air or inert gas to the interior of the cable body; A negative pressure generating system, comprising an air pipe and a negative pressure generating device arranged in the first groove, for forming a negative pressure environment in the cable body; The detection system includes a fiber grating sensor and a data processing and control unit. The fiber grating sensor is laid in the second groove to monitor the temperature and humidity data inside the cable body in real time. The data processing and control unit is communicatively connected with the fiber grating sensor, the air supply system and the negative pressure generation system, and dynamically adjusts the working status of the air supply system and the negative pressure generation system according to the temperature and humidity data.

2. The parallel steel cable negative pressure dehumidification and full-length detection system according to claim 1 is characterized in that: A plurality of functional steel wires are arranged in the steel wire bundle, and the functional steel wires are evenly distributed along the circumference of the steel wire bundle. Among the plurality of functional steel wires, at least one functional steel wire is located at the geometric center of the steel wire bundle.

3. The parallel steel cable negative pressure dehumidification and full-length detection system according to claim 1 is characterized in that: The gas supply system comprises: Gas generator, used to prepare dry air or inert gas; The inlet of the gas storage tank is connected to the outlet of the gas generator, and the outlet of the gas storage tank is sealed and connected to the air pipe.

4. The parallel steel cable negative pressure dehumidification and full-length detection system according to claim 3 is characterized in that: The gas supply system further comprises: a delivery pipe, one end of which is sealedly connected to the outlet of the gas storage tank and the other end of which is sealedly connected to the air pipe; an electric control valve, arranged on the delivery pipe; The valve controller is integrated into the electric control valve, communicates with the data processing and control unit, and adjusts the opening of the electric control valve according to the control instructions.

5. The parallel steel cable negative pressure dehumidification and full-length detection system according to claim 3 is characterized in that: The negative pressure generating device is an air extraction device, and the air extraction device includes: An air pump is provided at the second end of the cable body, and an inlet of the air pump is sealedly connected to the air pipe. When the air pump is in operation, the pressure at the inlet of the air pipe is lower than the internal pressure of the gas storage tank, so that the gas in the gas storage tank enters the air pipe; The vacuum pump controller is integrated into the vacuum pump, communicates with the data processing and control unit, and adjusts the speed of the vacuum pump according to the control instructions; The exhaust pipe is connected to the outlet of the vacuum pump.

6. The parallel steel cable negative pressure dehumidification and full-length detection system according to claim 1, characterized in that: The negative pressure generating device is an inflation device, and the inflation device includes: an inflator, hermetically connected between the air supply system and the air pipe. When the inflator is in operation, the gas pressure at the air pipe outlet is greater than the gas pressure outside the cable body. Under the action of the pressure difference, the gas is forced to flow from the air pipe outlet to the outside of the cable body, thereby driving the gas inside the air pipe to be discharged. The inflator forms a high-speed airflow inside the cable body by increasing the inflation rate, and uses the pressure difference to create a negative pressure environment inside the cable body. The inflator controller is integrated into the inflator, communicates with the data processing and control unit, and adjusts the speed of the inflator according to the control instructions.

7. The parallel steel cable negative pressure dehumidification and full-length detection system according to claim 1, characterized in that: The air pipe is provided with a moisture meter near the second end of the cable body.

8. The parallel steel cable negative pressure dehumidification and full-length detection system according to claim 1, characterized in that: The wall of the trachea is provided with a plurality of through holes spaced apart in the axial and circumferential directions, and the opening rate of a single trachea is greater than 0.5%.

9. The parallel steel cable negative pressure dehumidification and full-length detection system according to claim 1, characterized in that: The cross sections of the two grooves of the functional steel wire are both semicircular, the width of the first groove matches the outer diameter of the tracheal tube, and the width of the second groove matches the outer diameter of the fiber grating sensor.

10. A method for negative pressure dehumidification of parallel steel wire cables using the negative pressure dehumidification and full length detection system for parallel steel wire cables according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: The fiber Bragg grating sensor monitors the humidity inside the cable in real time. When the humidity inside the cable exceeds the set value, it is fed back to the data processing and control unit; S2: Start the air supply system to provide dry inert gas to the cable body, and then start the negative pressure generating system, wherein the air supply flow rate of the air supply system is greater than the inflation rate or exhaust rate of the inflation device or the exhaust device; S3: Using fiber grating sensors to monitor the humidity distribution inside the cable body over its entire length in real time, and transmitting the monitored data to the data processing and control unit in real time; S4: When the humidity in all areas within the entire length of the cable body remains stable within a relative humidity of 50% for more than 15 minutes, the dehumidification is determined to be complete.

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