A method for comprehensive improvement and monitoring of the durability of seawater desalination plant engineering

Abstract

The invention discloses a method for comprehensively improving and monitoring the durability of a desalination plant project, comprising the following steps: S1, using a half-cell potential method to measure the corrosion of steel bars, steel meshes and raft foundations in concrete; S2, using a linear polarization method to further detect the corrosion rate of steel bars; S3, using an AC impedance spectrum method to observe the microstructural changes of concrete after corrosion; S4, using an impressed current cathode protection method to avoid or weaken the occurrence of corrosion reactions; S5, using COMSOL simulation software to construct a chloride ion transmission model. The invention solves the durability problem in the construction of a desalination plant project; has a good effect in preventing steel bar corrosion; uses COMSOL simulation software to establish a chloride ion transmission model, combines monitoring data, and predicts the time and depth of corrosion with high accuracy; the monitoring structure system is complete; and can be promoted and applied to other corrosive concrete structures, with great promotion and application value.

Description

Technical Field

[0001] The invention relates to the field of seawater desalination, and in particular to a method for comprehensively improving and monitoring the engineering durability of a seawater desalination plant. Background Art

[0002] In the field of durability research of concrete structures in seawater environment, although a lot of achievements have been made in corrosion mechanism, repair, protection and durability design at home and abroad, due to the complexity of the problem, the current structural design standards can only indirectly reflect the requirements of the structure for service life through concrete proportion, protective layer thickness and other structural measures. For projects with complex service environments such as desalination plants, it is extremely important to dynamically obtain information feedback on key parameters of structural durability. Therefore, a series of online monitoring methods are needed to grasp the service status of concrete structures in real time, provide important basis for the protection and repair of the project, and ensure the safe operation of facilities in harsh environments.

[0003] At present, the structural design standards for desalination plants can only indirectly reflect the requirements for the service life of the structure through the concrete mix ratio, protective layer thickness and other structural measures. Existing technology cannot achieve effective monitoring. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings existing in the prior art, such as: the requirements of the structure for service life can only be indirectly reflected through the concrete mix ratio, the thickness of the protective layer and some other structural measures, and the prior art cannot achieve effective monitoring, and a method for comprehensively improving and monitoring the durability of a seawater desalination plant project is proposed.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] 1. A method for comprehensive improvement and monitoring of the durability of a seawater desalination plant project, comprising the following steps:

[0007] S1. Use the half-cell potential method to measure the corrosion of steel bars, steel mesh and raft foundation in concrete;

[0008] S2, use linear polarization method to further detect the corrosion rate of steel bars;

[0009] S3. Use AC impedance spectroscopy to observe the microstructural changes of concrete after corrosion;

[0010] S4. Use impressed current cathodic protection to avoid or reduce the occurrence of corrosion reactions;

[0011] S5. Use COMSOL simulation software to build a chloride ion transport model, combine the above series of monitoring data, that is, the data obtained in steps S1, S2 and S3, analyze and predict the time and depth of possible corrosion, and discuss the chloride ion penetration mechanism;

[0012] S6. Bury anode ladders and durability sensors, and use multi-source information fusion technology to process data, so that sensor nodes can fully cover the monitoring area as much as possible, and build an integrated structural durability monitoring system;

[0013] Arrange several measuring areas with an area not larger than 5.0m×5.0m on the concrete structure and components, and number each measuring area. Arrange measuring points in rows and columns in each measuring area. According to the size of the measured structure and components, a grid with an interval of 10cm can be used, and the potential measuring points are arranged at the nodes of the grid; then use a steel bar detector to detect the distribution of steel bars, chisel out steel bars at appropriate locations, connect one end of the wire to the negative terminal of the steel bar corrosion instrument, and the other end to the steel bars in the concrete; the steel bar surface at the connection should be derusted or cleaned of dirt to ensure the effective connection between the conductor and the steel bar; the steel bars or steel mesh in the measuring area must be connected to the connection The steel bars at the joint form an electrical path; then connect the instrument and check various interfaces to ensure that the instrument has good contact; one end is connected to the positive input terminal of the steel corrosion instrument, and the other end of the wire is connected to the copper and copper sulfate half-cell. The concrete in the test area should be fully soaked in advance; about 2% household liquid detergent can be added to drinking water to prepare a conductive solution, which is sprayed on the concrete surface of the test area to ensure good coupling between the instrument and the concrete surface; finally, each measuring point is tested in turn according to the test area number. In order to ensure that the porous plug of the half-cell forms an electrical path with the concrete surface, the adsorbent on the surface of the electrical connection pad should be removed in time during the test process;

[0014] When processing test data, the influence of temperature should be considered. When the test environment temperature is outside (22±5)℃, the potential value of the test point should be corrected according to the following formula:

[0015] When T≥27℃,

[0016] V=0.9×(T-27.0)+V R (1)

[0017] When T≤17℃,

[0018] V=0.9×(T-17.0)+V R (2)

[0019] Where, V is the corrected potential value, accurate to 1m V; V R —Test potential value, accurate to 1m V; T—temperature, accurate to 1°C; 0.9—coefficient (mV / °C);

[0020] The detection equipment is GECOR 6, which has three main components, the host and two independent sensors; the host LG-ECM-06 controls the system, collects and processes data; sensor A measures the steel bar corrosion current density icorr (μA / cm 2 ), steel corrosion potential Ecorr and concrete resistance; sensor B measures the resistivity of concrete, relative humidity and temperature of the surrounding environment;

[0021] During the on-site inspection, select an appropriate location and expose the steel bars in the column by 1 to 2 cm so that the host, sensor and the steel bars to be tested form a loop. Before the inspection, it is necessary to understand the distribution of the steel bars in the entire column, check the drawings to obtain the distribution and diameter of the steel bars, and use the steel bar detection instrument to detect the specific location of the steel bars in the concrete column. The surface area of ​​the steel bars needs to be input during the inspection, from which

[0022]

[0023] Where, 10.5 is the diameter range that the sensor can detect (cm); n is the number of layers of steel bars. When the number of layers of steel bars exceeds 3, only the influence of 2 layers of steel bars is considered; Di is the diameter of the steel bar to be measured (cm), which can be obtained from the drawing or the steel bar diameter measuring instrument;

[0024] Within a certain frequency range, by applying low-voltage, small-amplitude sinusoidal alternating current to the test material, its output response is measured and the corresponding impedance data is obtained. This is used to study the corrosion of concrete by sludge, and the concrete is repaired through protective and repairing integrated repair mortar to achieve comprehensive durability improvement.

[0025] Compared with the prior art, the beneficial effects of the present invention are: using the half-cell potential method and the linear polarization method to monitor the corrosion status and rate of steel bars, and using the AC impedance method to monitor the corrosion of sludge to concrete; using the impressed current cathodic protection method to avoid or weaken the occurrence of steel bar corrosion reactions in dry-wet alternating areas; while monitoring, using COMSOL simulation software to establish a chloride ion transmission model, combined with monitoring data, to predict the time and depth of corrosion. Burying anode ladders and durability sensors to build a complete set of monitoring structure systems. Thereby solving the durability problem faced by concrete structures widely used in the construction of seawater desalination plants; having a better effect in preventing steel bar corrosion; using COMSOL simulation software to establish a chloride ion transmission model, combined with monitoring data, to predict the time and depth of corrosion with high accuracy; the monitoring structure system is complete; it can be extended to other corrosive concrete structures, and has great promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1A schematic diagram of steel bar corrosion caused by chloride ion erosion in a method for comprehensive improvement and monitoring of the durability of a seawater desalination plant proposed by the present invention;

[0027] Figure 2 This is a schematic diagram of the half-cell potential method detection of a method for comprehensive improvement and monitoring of the engineering durability of a seawater desalination plant proposed by the present invention;

[0028] Figure 3 A schematic diagram of an impressed current cathodic protection system for a method for comprehensively improving and monitoring the durability of a seawater desalination plant proposed by the present invention;

[0029] Figure 4 This is a flow chart of a method for comprehensively improving and monitoring the durability of a seawater desalination plant project proposed by the present invention;

[0030] Figure 5 A schematic diagram of measuring steel corrosion using a half-potential method in a method for comprehensively improving and monitoring the durability of a seawater desalination plant project proposed by the present invention;

[0031] Figure 6 This is a schematic diagram of an integrated structure for anti-fouling protection and repair of seawater flushing pipelines and flotation tanks in a method for comprehensive improvement and monitoring of the durability of a seawater desalination plant project proposed by the present invention;

[0032] Figure 7 A COMSOL-based simulation of reinforced concrete chloride ion penetration process for a comprehensive improvement and monitoring method for the durability of a seawater desalination plant project proposed in the present invention;

[0033] Figure 8 The present invention proposes an anode ladder sensor for a method for comprehensively improving and monitoring the engineering durability of a seawater desalination plant and an installation mode for monitoring the durability of the seawater desalination plant structure. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0035] Reference Figure 1-8 A method for comprehensively improving and monitoring the durability of a desalination plant project comprises the following steps:

[0036] S1. Use the half-cell potential method to measure the corrosion of steel bars, steel mesh and raft foundation in concrete;

[0037] S2, use linear polarization method to further detect the corrosion rate of steel bars;

[0038] S3. Use AC impedance spectroscopy to observe the microstructural changes of concrete after corrosion;

[0039] S4. Use impressed current cathodic protection to avoid or reduce the occurrence of corrosion reactions;

[0040] S5. Use COMSOL simulation software to build a chloride ion transport model, combine the above series of monitoring data, that is, the data obtained in steps S1, S2 and S3, analyze and predict the time and depth of possible corrosion, and discuss the chloride ion penetration mechanism;

[0041] S6. Bury anode ladders and durability sensors, and use multi-source information fusion technology to process data, so that sensor nodes can fully cover the monitoring area as much as possible, and build an integrated structural durability monitoring system;

[0042] 2. Arrange several measuring areas with an area not larger than 5.0m×5.0m on the concrete structure and components, and number each measuring area. Arrange measuring points in rows and columns in each measuring area. According to the size of the structure and components to be measured, a grid with an interval of 10cm can be used, and the potential measuring points are arranged at the nodes of the grid; then use the steel bar detector to detect the distribution of steel bars, chisel out the steel bars at the appropriate position, connect one end of the wire to the negative terminal of the steel bar corrosion instrument, and the other end to the steel bars in the concrete; the steel bar surface at the connection should be derusted or cleaned of dirt to ensure the effective connection between the conductor and the steel bar; the steel bars or steel mesh in the measuring area must be connected to the steel bar. The steel bars at the connection form an electrical path; then connect the instrument and check various interfaces to ensure that the instrument has good contact; one end is connected to the positive input terminal of the steel corrosion instrument, and the other end of the wire is connected to the copper and copper sulfate half-cell. The concrete in the test area should be fully soaked in advance; about 2% household liquid detergent can be added to drinking water to prepare a conductive solution, which is sprayed on the concrete surface of the test area to ensure good coupling between the instrument and the concrete surface; finally, each measuring point is tested in turn according to the test area number. In order to ensure that the porous plug of the half-cell forms an electrical path with the concrete surface, the adsorbent on the surface of the electrical connection pad should be removed in time during the test process;

[0043] When processing test data, the influence of temperature should be considered. When the test environment temperature is outside (22±5)℃, the potential value of the test point should be corrected according to the following formula:

[0044] When T≥27℃,

[0045] V=0.9×(T-27.0)+V R (1)

[0046] When T≤17℃,

[0047] V=0.9×(T-17.0)+V R (2)

[0048] Where, V is the corrected potential value, accurate to 1m V; VR —Test potential value, accurate to 1m V; T—temperature, accurate to 1°C; 0.9—coefficient (mV / °C);

[0049] The detection equipment is GECOR 6, which has three main components, the host and two independent sensors; the host LG-ECM-06 controls the system, collects and processes data; sensor A measures the steel bar corrosion current density icorr (μA / cm 2 ), steel corrosion potential Ecorr and concrete resistance; sensor B measures the resistivity of concrete, relative humidity and temperature of the surrounding environment;

[0050] During the on-site inspection, select an appropriate location and expose the steel bars in the column by 1 to 2 cm so that the host, sensor and the steel bars to be tested form a loop. Before the inspection, it is necessary to understand the distribution of the steel bars in the entire column, check the drawings to obtain the distribution and diameter of the steel bars, and use the steel bar detection instrument to detect the specific location of the steel bars in the concrete column. The surface area of ​​the steel bars needs to be input during the inspection, from which

[0051]

[0052] Where, 10.5 is the diameter range that the sensor can detect (cm); n is the number of layers of steel bars. When the number of layers of steel bars exceeds 3, only the influence of 2 layers of steel bars is considered; Di is the diameter of the steel bar to be measured (cm), which can be obtained from the drawing or the steel bar diameter measuring instrument;

[0053] Within a certain frequency range, by applying low voltage and small amplitude sinusoidal alternating current to the test material, its output response is measured and the corresponding impedance data is obtained, so as to study the corrosion of concrete by sludge, and repair it through the protective and repairing integrated repair mortar to achieve comprehensive improvement of durability;

[0054] Impressed current cathodic protection is used to avoid or weaken the occurrence of corrosion reactions. The seawater flotation tanks in desalination plants are alternately wet and dry, and the concentration of seawater varies greatly. The alternation of wet and dry will enhance the capillary absorption of salt and lead to structural degradation. Therefore, not only should monitoring be done well, but protection should also be done at the same time. Impressed current cathodic protection is used to avoid or weaken the occurrence of corrosion reactions.

[0055] In the present invention, usually, the durability monitoring is mainly to monitor the corrosion condition of the steel bars in the structure. Since the operating conditions of the seawater desalination plant are relatively special, in order to enable the structure to better resist the erosion of high-concentration seawater, a steel mesh is added to the protective layer to increase the strength and durability. Since the steel mesh is located relatively close to the outside and is more susceptible to corrosion, it is necessary to detect the corrosion condition of the steel mesh. The corrosion condition of the steel mesh can be quickly obtained by using the half-cell potential method. In this way, not only can the corrosion of the steel bars inside the concrete be monitored, but also the corrosion problem of the outer steel mesh can be well grasped, thereby comprehensively evaluating the durability of reinforced concrete.

[0056] This project integrates monitoring, simulation and repair, comprehensively evaluates the durability of the desalination plant, and comprehensively improves its durability. It has obvious innovations and improvements in structural corrosion monitoring, the establishment of simulation models and the comprehensive improvement of durability. This integrated monitoring and protection system will save a lot of money for later maintenance, and the various technologies used and related engineering experience will also be well promoted.

[0057] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for comprehensive improvement and monitoring of the durability of a seawater desalination plant project, characterized in that: The following steps are involved: S1. Use the half-cell potential method to measure the corrosion of steel bars, steel mesh and raft foundation in concrete; S2, use linear polarization method to further detect the corrosion rate of steel bars; S3. Use AC impedance spectroscopy to observe the microstructural changes of concrete after corrosion; S4. Use impressed current cathodic protection to avoid or reduce the occurrence of corrosion reactions; S5. Use COMSOL simulation software to build a chloride ion transport model, combine the above series of monitoring data, that is, the data obtained in steps S1, S2 and S3, analyze and predict the time and depth of possible corrosion, and discuss the chloride ion penetration mechanism; S6. Bury anode ladders and durability sensors, and use multi-source information fusion technology to process data, so that sensor nodes can fully cover the monitoring area as much as possible, and build an integrated structural durability monitoring system; Arrange several measuring areas with an area not larger than 5.0m×5.0m on the concrete structure and components, and number each measuring area. Arrange measuring points in rows and columns in each measuring area. According to the size of the measured structure and components, a grid with an interval of 10cm can be used, and the potential measuring points are arranged at the nodes of the grid; then use a steel bar detector to detect the distribution of steel bars, chisel out steel bars at appropriate locations, connect one end of the wire to the negative terminal of the steel bar corrosion instrument, and the other end to the steel bars in the concrete; the steel bar surface at the connection should be derusted or cleaned of dirt to ensure the effective connection between the conductor and the steel bar; the steel bars or steel mesh in the measuring area must be connected to the connection The steel bars at the joint form an electrical path; then connect the instrument and check various interfaces to ensure that the instrument has good contact; one end is connected to the positive input terminal of the steel corrosion instrument, and the other end of the wire is connected to the copper and copper sulfate half-cell. The concrete in the test area should be fully soaked in advance; about 2% household liquid detergent can be added to drinking water to prepare a conductive solution, which is sprayed on the concrete surface of the test area to ensure good coupling between the instrument and the concrete surface; finally, each measuring point is tested in turn according to the test area number. In order to ensure that the porous plug of the half-cell forms an electrical path with the concrete surface, the adsorbent on the surface of the electrical connection pad should be removed in time during the test process; When processing test data, the influence of temperature should be considered. When the test environment temperature is outside (22±5)℃, the potential value of the test point should be corrected according to the following formula: When T≥27℃, V=0.9×(T-27.0)+V R (1) When T≤17℃, V=0.9×(T-17.0)+V R (2) Where, V is the corrected potential value, accurate to 1m V; V R —Test potential value, accurate to 1m V; T—temperature, accurate to 1°C; 0.9—coefficient (mV / ℃); The detection equipment is GECOR 6, which has three main components, the host and two independent sensors; the host LG-ECM-06 controls the system, collects and processes data; sensor A measures the steel bar corrosion current density icorr (μA / cm 2 ), steel corrosion potential Ecorr and concrete resistance; sensor B measures the resistivity of concrete, relative humidity and temperature of the surrounding environment; During the on-site inspection, select an appropriate location and expose the steel bars in the column by 1 to 2 cm so that the host, sensor and the steel bars to be tested form a loop. Before the inspection, it is necessary to understand the distribution of the steel bars in the entire column, check the drawings to obtain the distribution and diameter of the steel bars, and use the steel bar detection instrument to detect the specific location of the steel bars in the concrete column. The surface area of ​​the steel bars needs to be input during the inspection, from which Where, 10.5 is the diameter range that the sensor can detect (cm); n is the number of layers of steel bars. When the number of layers of steel bars exceeds 3, only the influence of 2 layers of steel bars is considered; Di is the diameter of the steel bar to be measured (cm), which can be obtained from the drawing or the steel bar diameter measuring instrument; Within a certain frequency range, by applying low-voltage, small-amplitude sinusoidal alternating current to the test material, its output response is measured and the corresponding impedance data is obtained. This is used to study the corrosion of concrete by sludge, and the concrete is repaired through protective and repairing integrated repair mortar to achieve comprehensive durability improvement.

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