A precise positioning method for sewer leakage based on concentration gradient color development principle

Abstract

The application provides a precise positioning method for sewer pipeline leakage based on a concentration gradient color development principle, and comprises the following steps: S1, fixing a color development tape connected with a deployer in a manhole upstream of a pipeline, allowing the deployer to advance spirally along a central axis direction of the pipeline, and continuously releasing the color development tape in the process, so that the color development tape is radially and tightly pressed and fixedly attached to an inner wall detection area of the pipeline, and is arranged along a spiral track in the central axis direction of the pipeline until the deployer reaches a manhole downstream of the pipeline; S2, continuously injecting a tracer upstream of the pipeline; S3, activating a color development reaction of the color development tape under a sewage environment, so as to form a color development intensity gradient corresponding to a pipeline leakage point in a length direction of the color development tape, and the color development intensity gradient is positively correlated with a pipeline leakage flow; and S4, continuously scanning the color development tape by using a colorimetric analyzer method to obtain color development intensity, and determining the pipeline leakage point and leakage intensity according to the color development intensity and color development tape position information.

Description

Technical Field

[0001] This invention belongs to the field of pipeline leakage detection, specifically involving a method for accurately locating leakage in drainage pipelines based on the concentration gradient colorimetric principle. Background Technology

[0002] Drainage pipes are widely used in modern urban construction, specifically including rainwater and sewage pipes under municipal roads. With social development and the expansion of urbanization, drainage pipes are laid extensively in densely populated areas such as cities, towns, and industrial parks. They are an indispensable component of modern engineering construction and a vital link in maintaining normal life and protecting the urban environment.

[0003] Leaks in drainage pipes are a critical issue that cannot be ignored in urban safety management. If leaks are not investigated and dealt with in a timely manner, they can lead to a series of chain reactions, such as forced water outages, waste of water and electricity, and asset depreciation, causing losses and inconvenience to people's lives. In addition, leaks in urban drainage pipes can also lead to water pollution, disease transmission, and damage to building structures, posing significant risks to human safety and health. Therefore, regular and timely inspections of drainage pipe leaks are an urgent problem to be solved.

[0004] Commonly used technologies for detecting leaks in drainage pipes include video detection, acoustic detection, gas tracer detection, pressure / flow detection, and tracer detection, among which: Video inspection technology is suitable for internal inspection of pipes with a diameter of ≥200mm. It can detect structural defects such as cracks and misalignments, as well as obvious leaks. Specifically, it consists of a crawling robot equipped with a high-definition camera, lighting module, and cable transmission system. Defects are judged by human intervention through real-time video transmission.

[0005] Acoustic detection technology is suitable for locating leaks in pressure pipelines, especially metal pipelines. Specifically, it is based on the principle of sound wave propagation during leakage, using distributed acoustic sensors to capture vibration signals at the leak point, and calculating the leak location through a time-difference positioning algorithm, with a positioning accuracy of approximately ±1m.

[0006] Gas tracer detection technology is used to detect minute leaks under conditions of no water flow. Specifically, it involves injecting a helium / hydrogen mixture into the pipeline and using a high-sensitivity gas detector to detect the gas escape point along the ground above the pipeline.

[0007] Pressure / flow detection technology is suitable for leakage assessment of closed pressure piping systems. Specifically, it involves installing pressure sensors or electromagnetic flow meters, establishing a hydraulic model to analyze abnormal pressure-flow changes, and calculating the location of the leakage point.

[0008] Tracer detection technology is suitable for detecting hidden leaks or cross-contamination between adjacent pipes. It is commonly used in gravity flow pipe systems. Specifically, it involves adding staining agents such as sodium fluorescein or rhodamine B, and then using an ultraviolet lamp or spectrometer to track the migration path of the tracer.

[0009] For leak detection in urban underground drainage networks, particularly in non-metallic pipes such as concrete and HDPE pipes that exhibit minor leaks, extensive pipe wall deposits, and gravity flow (not full-pipe flow), the above-mentioned detection technologies all have significant technical limitations: (1) Video inspection technology: Optical lenses are easily blocked or interfered with by oil stains, biofilms and other deposits on the pipe wall, resulting in blurred images and inability to identify minute cracks <2 mm. CCTV optical systems are limited by the lens focal length and cannot capture details at the top / bottom of the pipe, resulting in a blind spot of about 30% of the area. In addition, video inspection relies on manual image interpretation, which is inefficient and has a high rate of missed detection.

[0010] (2) Acoustic detection technology: In non-metallic pipes such as concrete and HDPE pipes, the sound wave signal generated by water leakage is severely attenuated and has a short propagation distance. In addition, the background noise interference from the non-full pipe and flowing water in gravity flow pipes makes it difficult for the sensor to capture an effective signal, resulting in a positioning error as high as 3~5 m, which cannot meet the requirements of centimeter-level accuracy.

[0011] (3) Gas tracer detection technology: This method requires the inside of the pipeline to be dry or gaseous, which is completely unapplicable in the above-mentioned pipeline network filled with actual sewage, and it is impossible to trace tracer gases in flowing water.

[0012] (4) Pressure / flow detection technology: This technology is mainly applicable to closed water supply networks with stable pressure. In the above-mentioned gravity flow, non-full pipe and branch pipes along the way drainage network, the pressure and flow background fluctuate greatly, making it difficult to establish a stable hydraulic model. Therefore, it is impossible to reliably locate the leakage point by pressure drop or flow difference.

[0013] (5) Traditional tracer detection technology: In the turbulent water flow in the scenario, traditional fluorescent tracers such as sodium fluorescein diffuse too quickly and their concentration is rapidly diluted, making it difficult to form a stable concentration gradient that can be detected downstream of the leak point; at the same time, the background color and turbidity of the sewage will seriously interfere with the observation of the tracer by the naked eye or ordinary optical equipment, resulting in low detection sensitivity and blurred positioning.

[0014] In summary, given the complex situation of non-metallic pipes in urban underground drainage networks, existing detection technologies cannot achieve the expected detection results. Therefore, there is an urgent need to develop a precise method for locating drainage pipe leaks, overcome the above shortcomings, and provide a new method for investigating drainage pipe leaks in modern environmental industries. Summary of the Invention

[0015] In view of this, the purpose of this invention is to overcome the technical defects of existing drainage pipe leakage detection methods, such as high false negative rate, low accuracy and blind spot, and to provide a precise location method for drainage pipe leakage based on the concentration gradient color development principle.

[0016] To achieve the above objectives, the present invention proposes the following technical solution: Firstly, a method for accurately locating leaks in drainage pipes based on the concentration gradient colorimetric principle is proposed, including the following steps: S1. Fix a distributor connected to a color-developing tape in the upstream inspection well of the pipeline, and make the distributor spiral forward along the central axis of the pipeline, while continuously releasing the color-developing tape in this process, so that the color-developing tape is radially and tightly pressed and fixedly attached to the detection area of ​​the inner wall of the pipeline, and is laid along the central axis of the pipeline in a spiral trajectory until the distributor reaches the downstream inspection well of the pipeline. S2. Continuously inject tracer upstream of the pipeline; S3. The color-developing band activates a color-developing reaction in a wastewater environment, thereby forming a color intensity gradient corresponding to the pipeline leakage point along the length of the color-developing band. The color intensity gradient is positively correlated with the pipeline leakage flow rate. S4. After separating the color-developing tape from the distributor, peel the color-developing tape off the inner wall of the pipe at a constant speed from the starting end of the color-developing tape along the opposite direction of its layout and collect it. Then, use a colorimeter to continuously scan along the collected color-developing tape to obtain the color intensity. Based on the color intensity and the position information of the color-developing tape, determine the leakage point and leakage intensity of the pipe.

[0017] Furthermore, the deployer includes a power supply mechanism, a rotating frame, a drive mechanism, a rolling mechanism, and a guiding mechanism; The rotating frame includes a support base, a front plate, and a rear plate, with the front plate and the rear plate respectively connected to both ends of the support base; The drive mechanism includes a drive connecting shaft, a motor, and a coupling. The drive connecting shaft is axially inserted into the support base and fixedly connected to the support base. The front end of the drive connecting shaft passes through the bearing in the center of the front plate. The motor is connected to the drive connecting shaft via the coupling. The power supply mechanism includes a power source and wires, and the power source is connected to the motor through the wires; The rolling mechanism includes a plurality of rolling components, which are evenly distributed along the circumference of the support base and are arranged in parallel at intervals on the outside of the support base. The guiding mechanism includes at least one guiding block, each of which is disposed on the support base. Each guiding block has a guiding groove, through which the color developing tape passes, so that the color developing tape entering the distributor is guided to the outside of the rolling assembly and radially pressed into the inside of the pipe. The drive assembly drives the rotating frame to rotate radially at a uniform speed along the extension direction of the drive connection shaft, which in turn drives the rolling mechanism to rotate, thereby pushing the distributor to move forward spirally along the central axis of the pipeline. During this process, the rolling mechanism continuously releases the color developing strip, so that the color developing strip is radially and tightly pressed against the rolling assembly and fixedly attached to the detection area on the inner wall of the pipeline.

[0018] Furthermore, the rolling mechanism includes a support arm, a traveling wheel, and a pressure roller; The support arm is evenly arranged along the circumference of the side of the support base and connected to the support base. The traveling wheel and the pressing roller are rotatably connected to the support arm. A plurality of traveling wheels are distributed along the circumference of the support arm, and a plurality of pressing rollers are arranged parallel and spaced apart on the support arm. The axle of the traveling wheel has an inclination angle relative to the vertical direction of the axle of the pressure roller, so that when the traveling wheel contacts the inner wall of the pipe, the inclination angle generates an axial force, thereby pushing the distributor to move forward spirally along the central axis of the pipe. The rolling assembly includes a first support arm, a second support arm, a first traveling wheel, a second traveling wheel, a first pressure roller, and a second pressure roller; The first support arm and the second support arm have the same structure, both being T-shaped structures, including a horizontal section and a vertical section, with the upper end of the vertical section connected to the lower middle part of the horizontal section; The first traveling wheel and the second traveling wheel are respectively rotatably connected to the upper side of the corresponding horizontal segment of the first support arm and the second support arm; The axles of the first traveling wheel and the second traveling wheel are arranged in parallel, and the axles of the first pressure roller and the second pressure roller are arranged in parallel. The first support arm and the second support arm are respectively connected to the opposite ends of the support base, and their corresponding lower ends of the vertical sections are respectively fixedly connected to the outer wall of the support base. The first pressure roller and the second pressure roller are rotatably connected between the first support arm and the second support arm, respectively. The two ends of the first pressure roller are respectively connected to one end of the corresponding horizontal segment of the first support arm and the second support arm, and the two ends of the second pressure roller are respectively connected to the other end of the corresponding horizontal segment of the first support arm and the second support arm, so that the free end of the color developing strip is guided by the guiding mechanism and is radially and tightly pressed and fixedly attached to the detection area of ​​the inner wall of the pipe at any of the pressure rollers.

[0019] Furthermore, the guiding mechanism includes a first guiding block, a second guiding block, and a third guiding block; The first guide block, the second guide block and the third guide block are all rectangular block structures and are distributed sequentially along the axial direction of the support base. They are respectively provided with a first guide groove, a second guide groove and a third guide groove. The first guide groove, the second guide groove and the third guide groove are all provided with rotatable guide wheels inside. The first guide block is installed on the inner side of the rear plate facing the support base and is fixedly connected to the rear plate. The extension direction of the first guide groove is parallel to the axial direction of the distributor, and its inlet is directly opposite to the starting end of the color developing tape, so that the outlet direction of the color developing tape passing through the outlet of the first guide groove is parallel to the axial direction of the distributor. The second guide block is fixedly connected to the outer side of the middle part of the support base by any of the support arms and is located between the support base and the walking wheel. The inlet of the second guide groove receives the color-developing strip that passes through the first guide block and deflects its traveling direction from the axial direction of the distributor. The third guide block is installed on the inner side of the front plate facing the support base and is fixedly connected to the front plate. The inlet of the third guide groove receives the color developing strip that passes through the second guide block and guides its travel direction to the radial direction of the distributor. The outlet of the third guide groove is aligned with the tangent point of any of the pressure rollers and the inner wall of the pipe. The central axis of the third guide groove is perpendicular to the central axis of the distributor.

[0020] Furthermore, the color developing strip includes a first fiber layer, a second fiber layer, a memory skeleton, and several color developing labels; The memory skeleton is disposed between the first fiber layer and the second fiber layer. The memory skeleton undergoes a phase change at a preset temperature so that the first fiber layer located inside the color band is tightly attached to the inner wall of the pipe. A number of color-developing units are arranged sequentially at a fixed length distance along the length direction of the color-developing strip, and the color-developing labels are correspondingly arranged in the middle area of ​​the color-developing units and embedded between the first fiber layer and the second fiber layer.

[0021] Furthermore, quaternary ammonium salt groups are grafted onto the surface of the second fiber layer; The grafting method for the quaternary ammonium salt group includes the following steps: The second fiber layer was pretreated with 5% NaOH solution at 60°C, and then immersed in an ethanol solution containing 2-5 wt% 3-aminopropyltriethoxysilane for 2-4 h at room temperature; then the second fiber layer was immersed in a hexadecyltrimethylammonium bromide solution and reacted at 60-80°C for 4-6 h; then the second fiber layer was thoroughly washed with deionized water and vacuum dried at 50°C to constant weight. The grafting amount of the quaternary ammonium salt is 0.1~0.5 mmol / g, and the density of the quaternary ammonium salt groups is 0.5~2.5 μmol / cm².

[0022] Furthermore, in S2, a smart injection module is used to continuously inject tracer upstream of the pipeline, the tracer being a mixture of a main tracer and an auxiliary tracer; The intelligent injection module includes a dual-plunger pump assembly and a mixing injection head; The dual-plunger pump assembly includes a main agent tank, a main agent pump, an auxiliary agent tank, and an auxiliary agent pump. The main agent tank contains a main tracer, the auxiliary agent tank contains an auxiliary tracer, the main agent tank is connected to the main agent pump, and the auxiliary agent tank is connected to the auxiliary agent pump. The mixing nozzle includes a Y-type mixer and a nozzle, wherein the Y-type mixer includes a first pipe, a second pipe, and a mixing pipe, the first pipe and the second pipe are respectively connected to the mixing pipe, and the mixing pipe is connected to the nozzle; the first pipe and the second pipe are respectively connected to the main agent pump and the auxiliary agent pump, so that the main tracer and the auxiliary tracer enter the mixing pipe through the first pipe and the second pipe respectively, and are sprayed out through the nozzle.

[0023] Furthermore, the main tracer is a sulfonated rhodamine B derivative solution with a concentration of 0.8 g / L and a pH of 7.2, and the flow rate accuracy of the main agent pump is ±2 mL / s, and the flow rate is 10~100 mL / min; The auxiliary tracer is a nano zinc oxide catalyst suspension with a concentration of 0.2 g / L, the nano zinc oxide has a particle size of 50 nm, and the auxiliary agent pump has a flow accuracy of ±1 mL / s and a flow rate of 2~20 mL / min. In step S2, the tracer is first continuously injected upstream of the pipeline for 5 minutes at a flow rate of 80 mL / min, wherein the flow ratio of the main agent pump and the auxiliary agent pump is 4:1. Then, 100 mL of the main tracer was injected into the pipeline every 1 minute, the concentration of the main tracer being 0.8 g / L, for 25 minutes.

[0024] Furthermore, in step S4, the distributor located in the downstream inspection well is lifted to the ground, and the color-developing strip is peeled off from the distributor; at the upstream inspection well, the color-developing strip is peeled off from the inner wall of the pipe from the starting end of the color-developing strip in the opposite direction to its laying direction and pulled out; when the color-developing strip is pulled out, a cooling medium with a temperature lower than the preset temperature is introduced into the pipe to soften the memory skeleton; A portable colorimeter is used to scan the colorimetric band, and its color intensity is quantified by a colorimetric model. The section where the color intensity changes beyond a preset value is automatically identified as a valid leakage signal. The colorimetric location information of the colorimetric band corresponding to the valid leakage signal is obtained by the position encoding of the colorimetric label, thereby determining the location and intensity of the pipeline leakage.

[0025] Furthermore, the colorimetric model is the CIE Lab* color space, and the preset value is ΔE≥5; The colorimetric positioning information is obtained by reading the colorimetric label, and the spatial resolution of the colorimetric positioning information is ±5 cm. The portable colorimeter has a spectral response range covering the visible light band, which is 380 nm to 850 nm.

[0026] The beneficial effects of this invention are: This invention overcomes the shortcomings of existing drainage pipe leakage detection technologies by employing a multi-system synergy of machine deployment, chemical colorimetry, and quantitative analysis. It achieves precise location of leak points and quantitative assessment of leakage volume in internal drainage pipe inspections. Specifically, it includes: (1) This invention sets up color-developing units at fixed intervals on the color-developing strip and embeds color-developing labels. At the same time, the color-developing strip is laid out along the central axis of the pipeline in a spiral trajectory. On the one hand, it realizes the linkage between the precise positioning information of the color-developing strip and the pipeline position information, and thus accurately corresponds the detection information with the pipeline position. The positioning accuracy can reach ±5 cm, which is much higher than the "interval" judgment that traditional methods such as video detection technology can only provide. On the other hand, the spiral layout of the color-developing strip greatly improves the pipe wall coverage and includes the blind area details of the pipe top / bottom in the existing technology into the detection range, which significantly reduces the missed detection rate.

[0027] (2) The present invention uses a portable colorimeter and an international standard color space to convert the color depth observed by the naked eye into objective and quantifiable color data. By setting a preset value as an effective leakage threshold, background interference is effectively eliminated, and the color intensity and leakage degree are positively correlated. This enables accurate judgment of pipeline leakage points while analyzing and obtaining the degree of leakage, which facilitates subsequent maintenance and repair of the entire pipeline.

[0028] (3) In this invention, quaternary ammonium salt groups are grafted onto the surface of the outer fiber layer of the colorimetric band, and sulfonated rhodamine B derivative solution is used as the main tracer and nano zinc oxide catalyst suspension is used as the auxiliary tracer. When the tracer comes into contact with the colorimetric band, on the one hand, the high porosity of the outer fiber layer accelerates the initial adsorption, and then the lower porosity of the inner fiber layer prolongs the residence time of the solution molecules, resulting in a better colorimetric effect. On the other hand, the quaternary ammonium salt groups grafted onto the surface of the outer fiber layer capture the negatively charged sulfonated rhodamine B molecules through Coulomb force. Strong electrostatic adsorption is generated on the surface of the quaternary ammonium salt modified fiber. The nano zinc oxide generates heat through friction in the specific turbulent environment inside the pipe, which leads to the colorimetric reaction of sulfonated rhodamine B molecules.

[0029] As temperature increases, the diffusion and adsorption rates of sulfonated rhodamine B molecules into the fiber pores also accelerate, leading to an increase in dye molecule enrichment per unit area. This results in increased pipeline seepage flow, increased flow velocity at the leak point, and, in conjunction with the increased temperature, improved mass transfer rate. The turbulent energy at the leak point thins the diffusion boundary layer, reducing mass transfer resistance. Since the viscosity of wastewater is temperature-sensitive, higher temperatures decrease viscosity, reducing fluid resistance and increasing the mass transfer rate of sulfonated rhodamine B. Consequently, the molecular weight of sulfonated rhodamine B adsorbed by the color band also increases, and the catalytic temperature also rises, resulting in increased color intensity. This ensures a positive correlation between color intensity and pipeline seepage flow.

[0030] (4) Based on the above-mentioned colorimetric band and tracer scheme, this invention combines the pre-injection + pulse injection strategy of the intelligent injection module, which significantly improves the capture efficiency of the colorimetric band for tracers and the colorimetric signal-to-noise ratio. This method can effectively activate and maintain a clear colorimetric gradient in actual sewage environments filled with dirt, oil film and background color, and has extremely high detection sensitivity for tiny leaks such as "wet spots" and "seepage" that are difficult to detect by traditional methods. Unlike gas detection methods that rely on the air environment inside the pipeline, this method works directly in the pipe flow filled with sewage, and is not limited by the pipe level, filling degree or gas diffusion performance. It also overcomes the defect of traditional tracers diffusing too quickly in turbulent flow, resulting in higher detection accuracy and wider applicability.

[0031] (5) This invention utilizes an innovative spiral-forward laying device to complete the continuous laying of color-developing tape along the entire pipeline in a single operation. Compared to traditional equipment that requires point-by-point measurements, this significantly improves detection efficiency, achieving seamless and complete scanning of the entire pipeline length and avoiding the randomness of point-based detection. By setting up a laying device that automatically spirals forward within the pipeline and presses the color-developing tape onto it, the risks and labor intensity of manual entry into the pipeline or prolonged underground operations are greatly reduced. All major operations are completed at the manhole, maximizing personnel safety. Furthermore, this method avoids costly operations such as excavation or large-scale pipeline emptying, resulting in low overall detection costs and significant benefits.

[0032] In summary, this invention establishes for the first time a circumferential adsorption gradient model of the pipe wall, breaking through the limitations of traditional point-based detection; develops a composite tracer system with time-varying color development characteristics; innovatively designs a flexible chain-type detection structure to adapt to complex pipe network morphologies; and proposes a quantitative leakage judgment algorithm with detection accuracy down to the millimeter level.

[0033] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below can be considered part of the inventive subject matter of this disclosure, provided that such concepts do not contradict each other. Attached Figure Description

[0034] The accompanying drawings are not drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a cross-sectional schematic diagram of the color developing strip after it has been laid out in an embodiment of the present invention; Figure 2 This is a schematic diagram of the distribution device rotating frame in an embodiment of the present invention; Figure 3 This is a schematic diagram of the rolling assembly of the distributor in an embodiment of the present invention; Figure 4 This is a schematic diagram of the distributor drive connection shaft in an embodiment of the present invention; Figure 5 This is a schematic diagram of the distribution guide block in an embodiment of the present invention; Figure 6 This is a schematic diagram of the overall structure of the deployer in an embodiment of the present invention; Figure 7 This is a schematic diagram of the deployment state of the deployer in an embodiment of the present invention; Figure 8 This is a schematic diagram of the intelligent injection module in an embodiment of the present invention.

[0035] Legend: 1. Color developing band; 1.1. Second fiber layer; 1.2. Memory skeleton; 1.3. First fiber layer; 2. Laying device; 2.1 Power supply; 2.2 Support base; 2.3 Front plate; 2.4 Rear plate; 2.5 Drive connecting shaft; 2.6 Walking wheels; 2.7 Pressure roller; 2.8 Support arm; 2.9 First guide block; 2.10 Second guide block; 2.11 Third guide block; 2.12 Wires; 2.13 Motor; 2.14 Coupling; 3. Intelligent injection module; 3.1 Main agent tank; 3.2 Main agent pump; 3.3 Auxiliary agent tank; 3.4 Auxiliary agent pump; 3.5 Y-type mixer; 3.6 Nozzle. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art.

[0037] The terms "first," "second," and similar words used in the specification and claims of this patent application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. Terms such as "comprising" or "including" mean that the element or object preceding "comprising" encompasses the features, integrals, steps, operations, elements, and / or components listed following "comprising" or "including," and do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof.

[0038] Unless otherwise stated, the abbreviations used in this invention have the following meanings: In this invention, PTFE refers to polytetrafluoroethylene; EPDM refers to ethylene propylene diene monomer (EPDM) rubber.

[0039] For leak detection in urban underground drainage pipe networks, specifically in non-metallic pipes such as concrete and HDPE pipes, where there are minor leaks, numerous deposits on the pipe walls, and non-full-pipe flow with gravity flow, this invention discloses a detection system based on the concentration gradient colorimetric principle for precise location of drainage pipe leaks. The system includes a colorimetric strip 1, a distributor 2, and an intelligent injection module 3.

[0040] See attached document Figure 1 The color developing band 1 includes a first fiber layer 1.3, a second fiber layer 1.1, a memory skeleton 1.2, and several color developing labels.

[0041] The memory skeleton 1.2 is disposed between the first fiber layer 1.3 and the second fiber layer 1.1. The memory skeleton 1.2 undergoes a phase change at a preset temperature so that the first fiber layer 1.1 located inside the color developing band 1 is tightly attached to the inner wall of the pipe.

[0042] Both the first fiber layer 1.3 and the second fiber layer 1.1 are made of polyacrylonitrile-based carbon fiber layers. The first fiber layer 1.3 is the inner adsorption fiber layer, which is attached to the inner wall of the pipe, and the second fiber layer 1.1 is the outer adsorption fiber layer. The outer adsorption fiber layer has a porosity of 70%, which can accelerate the initial adsorption of the tracer. The inner adsorption fiber layer has a porosity of 65%, which, together with the outer adsorption fiber layer, can prolong the residence time and support the memory skeleton 1.2 and the color-developing label.

[0043] The memory skeleton 1.2 is made of nickel-titanium alloy wire and is located between the first fiber layer 1.3 and the second fiber layer 1.1. It undergoes a phase change at around 35~37℃, which can improve the adhesion of the color developing band to the wall.

[0044] Specifically, the phase transformation of the alloy of the aforementioned memory skeleton 1.2 refers to the decrease in elastic modulus, making it easier to bend and deform, so that the first fiber layer wrapped around the alloy can fit more tightly to the uneven surface of the inner wall of the pipe.

[0045] Several color-developing units are arranged sequentially at a fixed length distance along the length direction of the color-developing strip 1. Color-developing labels are correspondingly arranged in the middle area of ​​the color-developing units and embedded between the first fiber layer 1.3 and the second fiber layer 1.1, with a spatial resolution of ±5cm.

[0046] Specifically, several color-developing units are arranged sequentially every 50 cm along the length of color-developing band 1, and the fixed length distance can be adjusted according to actual needs.

[0047] Specifically, the aforementioned color-coded tags are essentially RFID tags used for positioning, and the encapsulation shell is made of PET or PP film that does not absorb tracers.

[0048] The specific methods for embedding color-coded labels include: First, the inner adsorbent fiber layer is laid, then the shaped memory skeleton 1.2 is laid on the inner adsorbent fiber layer, the color label is placed in an area without interference from the memory skeleton 1.2, and finally the outer adsorbent fiber layer is covered. The fiber layer is partially melted by hot pressing molding process, fixing the memory skeleton 1.2 and the color label in the fiber layer.

[0049] The aforementioned memory skeleton 1.2 can be pre-defined as a continuous wave shape, or it can be set and adjusted according to actual needs.

[0050] The second fiber layer 1.1 is grafted with quaternary ammonium salt groups, specifically using a surface chemical grafting method. The grafting method includes the following steps: pretreating the fiber layer with a 5% NaOH solution at 60°C, then immersing the pretreated fiber layer in an ethanol solution containing 2–5 wt% 3-aminopropyltriethoxysilane at room temperature for 2–4 h to introduce amino groups onto the fiber surface; then immersing the fiber layer in a hexadecyltrimethylammonium bromide solution and reacting at 60–80°C for 4–6 h to graft quaternary ammonium salt groups onto the fiber surface; after the reaction, thoroughly washing the fiber layer with deionized water to remove unreacted substances, and then vacuum drying at 50°C to constant weight. The typical grafting amount is controlled at 0.1–0.5 mmol / g fiber (based on quaternary ammonium salt), and the surface group density is approximately 0.5–2.5 μmol / cm².

[0051] See attached document Figures 2-7 The deployer 2 includes a power supply mechanism, a rotating frame, a drive mechanism, a rolling mechanism, and a guiding mechanism.

[0052] The rotating frame includes a support base 2.2, a front plate 2.3, and a rear plate 2.4, with the front plate 2.3 and the rear plate 2.4 respectively connected to both ends of the support base 2.2.

[0053] The drive mechanism includes a drive connecting shaft 2.5, a motor 2.13, and a coupling 2.14. The drive connecting shaft 2.5 is axially inserted into the support base 2.2 and is fixedly connected to the support base 2.2. The front end of the drive connecting shaft 2.5 passes through the bearing in the center of the front plate 2.3. The motor 2.13 is connected to the drive connecting shaft 2.5 through the coupling 2.14.

[0054] The power supply mechanism includes a power source 2.1 and a wire 2.12. The power source 2.1 is connected to the motor 2.13 via the wire 2.12.

[0055] The rolling mechanism includes several rolling components, which are evenly distributed around the support 2.2 and are arranged in parallel at intervals on the outside of the support 2.2.

[0056] Specifically, the rolling mechanism includes a support arm 2.8, a traveling wheel 2.6, and a pressure roller 2.7.

[0057] The support arm 2.8 is evenly arranged along the side of the support base 2.2 and connected to the support base 2.2. The traveling wheel 2.6 and the pressing roller 2.7 are rotatably connected to the support arm 2.8. Several traveling wheels 2.6 are distributed along the circumference of the support arm 2.8, and several pressing rollers 2.7 are arranged in parallel at intervals on the support arm 2.8.

[0058] The axle of the traveling wheel 2.6 has an inclination angle relative to the vertical direction of the axle of the pressure roller 2.7. The inclination angle can be 5° to 25°, so that when the traveling wheel 2.6 contacts the inner wall of the pipe, the inclination angle generates an axial force, which in turn pushes the distributor 2 to move forward spirally along the central axis of the pipe.

[0059] The rolling assembly includes a first support arm, a second support arm, a first traveling wheel, a second traveling wheel, a first pressure roller, and a second pressure roller; the first support arm and the second support arm have the same structure, both being T-shaped structures, including a horizontal section and a vertical section, with the upper end of the vertical section connected to the lower middle part of the horizontal section.

[0060] The first traveling wheel and the second traveling wheel are rotatably connected to the upper side of the corresponding horizontal sections of the first support arm and the second support arm, respectively; the axles of the first traveling wheel and the second traveling wheel are arranged in parallel, and the axles of the first pressure roller and the second pressure roller are arranged in parallel.

[0061] The first and second support arms are respectively connected to the opposite ends of the support base, and their corresponding vertical lower ends are respectively fixedly connected to the outer wall of the support base.

[0062] The first and second pressure rollers are rotatably connected between the first and second support arms, respectively. The two ends of the first pressure roller are connected to one end of the corresponding horizontal section of the first and second support arms, respectively, and the two ends of the second pressure roller are connected to the other end of the corresponding horizontal section of the first and second support arms, respectively, so that the free end of the color developing band 1 is guided by the guiding mechanism and is radially and tightly pressed and fixedly attached to the inner wall detection area of ​​the pipeline at the pressure roller 2.7.

[0063] The guiding mechanism includes a first guiding block 2.9, a second guiding block 2.10, and a third guiding block 2.11, all of which are rectangular block structures and are distributed sequentially along the axial direction of the support base 2.2. A first guiding groove, a second guiding groove, and a third guiding groove are respectively provided on them. The first guiding groove, the second guiding groove, and the third guiding groove are all provided with rotatable guide wheels inside, which are used to guide and change the extension direction of the color developing band 1.

[0064] The first guide block 2.9 is located near the rear plate 2.4, with its inlet aligned with the free end of the color developing tape 1 entering the distributor 2; the second guide block 2.10 is fixed to the outer side of the middle of the support base 2.2; the third guide block 2.11 is located near the front plate 2.3, with its outlet radially aligned with any of the pressure rollers 2.7. The color developing tape 1 is drawn out from the internal reel, passes sequentially through the first guide block 2.9, the second guide block 2.10, and the third guide block 2.11, and its direction is gradually guided from the axial direction of the distributor 2 to the radial direction, finally exiting from the outlet of the third guide block 2.11, and radially pressed against the inner wall of the pipe by the pressure roller 2.7, which has been rotated to that position.

[0065] Furthermore, the first guide block 2.9 is installed on the inner side of the rear plate 2.4 facing the support base 2.2 and is fixedly connected to the rear plate 2.4. The extension direction of the first guide groove is parallel to the axial direction of the distributor 2, and its inlet is directly opposite to the starting end of the color developing tape 1 so that the outlet direction of the color developing tape 1 passing through the outlet of the first guide groove is parallel to the axial direction of the distributor 2.

[0066] Specifically, the rectangular or trapezoidal base of the first guide block 2.9 is rigidly connected to the rear plate 2.4 by bolts or welding. Simultaneously, its side can be auxiliaryly connected to the rear outer wall of the support base 2.2 via reinforcing ribs or connecting rods to enhance structural stability. The inlet axis of the first guide groove on the first guide block 2.9 is substantially parallel to the axial direction of the distributor 2 and faces the output direction of the reel from which the developing tape 1 is wound. This groove receives the developing tape 1 drawn from the tangential direction of the reel and initially guides it to a horizontal direction close to the axial direction.

[0067] Furthermore, the second guide block 2.10 is fixedly connected to the outer side of the middle part of the support base 2.2 by any support arm 2.8 and is located between the support base 2.2 and the traveling wheel 2.6. The inlet of the second guide groove receives the color-developing strip 1 that passes through the first guide block 2.9 and deflects its traveling direction from the axial direction of the distributor 2.

[0068] Specifically, one end of the aforementioned support arm 2.8 is fixed to the outer wall of the support base 2.2, and the other end carries the second guide block 2.10, positioning it axially in the middle region between the first guide block 2.9 and the third guide block 2.11, and radially within the space between the support base 2.2 and the traveling wheel 2.6. The second guide groove inlet on the second guide block 2.10 receives the color developing strip 1 from the first guide block 2.9, and has a rotatable guide wheel inside. As the color developing strip 1 passes through the guide wheel, its direction of travel gradually deflects from the axial direction to an angle of 30° to 60° with the axial direction of the distributor 2, achieving a transitional guidance of the color developing strip 1 from the axial to the radial direction.

[0069] Furthermore, the third guide block 2.11 is installed on the inner side of the front plate 2.3 facing the support base 2.2 and is fixedly connected to the front plate 2.3. The inlet of the third guide groove receives the color-developing strip 1 that passes through the second guide block 2.10 and guides its travel direction to the radial direction of the distributor 2. The outlet of the third guide groove is aligned with the tangent point of any pressure roller 2.7 in contact with the inner wall of the pipe. The central axis of the third guide groove is perpendicular to the central axis of the distributor 2.

[0070] Specifically, the inlet of the third guide groove on the third guide block 2.11 receives the color developing strip 1 from the second guide block 2.10, and the outlet is aligned with the tangent point where the pressure roller 2.7 and the inner wall of the pipe are about to contact. The central axis of the third guide groove is finally adjusted to be perpendicular to the central axis of the distributor 2, ensuring that the color developing strip 1 is accurately guided to the bottom of the pressure roller 2.7 and pressed radially against the inner wall of the pipe.

[0071] In use, the free end of the developing tape 1 is pulled out. The pulled-out developing tape 1 first enters the first guide block 2.8, which adjusts it from the tangential direction of the reel to a near-axial horizontal direction. Subsequently, the developing tape 1 enters the second guide block 2.9, which has guide grooves or rollers inside, gradually deflecting the direction of the developing tape 1 from the axial direction to a radial or near-radial angle. Finally, the developing tape 1 passes through the third guide block 2.10, where it is precisely positioned and guided to the front of the pressure roller 2.7. As the distributor 2 moves forward and rotates, the pressure roller 2.7 radially and tightly presses and adheres the developing tape 1 to the inner wall of the pipe.

[0072] When the distributor 2 is in use, the drive assembly drives the rotating frame to rotate radially at a uniform speed along the extension direction of the drive connecting shaft 2.5, which in turn drives the rolling mechanism to rotate, thereby pushing the distributor 2 to move forward spirally along the central axis of the pipeline. During this process, the rolling mechanism continuously releases the color developing tape 1 so that the color developing tape 1 is radially and tightly pressed and fixedly attached to the detection area on the inner wall of the pipeline at the pressure roller 2.7.

[0073] During this process, the traveling wheel 2.6 leads the laying area of ​​the color developing tape 1. The traveling wheel 2.6 is positioned at the very front of the laying device 2, while the pressing point of the color developing tape 1 is behind the traveling wheel 2.6. The traveling wheel 2.6 first contacts and rolls over a section of the pipe wall. Then, the forward movement of the laying device 2 drives the pressing roller 2.7 to press the color developing tape 1 onto the section of the pipe wall that has just been passed.

[0074] See attached document Figure 8The intelligent injection module 3 includes a dual-plunger pump assembly and a mixing injection head. The dual-plunger pump assembly includes a main agent tank 3.1, a main agent pump 3.2, an auxiliary agent tank 3.3, and an auxiliary agent pump 3.4. The main agent tank 3.1 contains the main tracer, and the auxiliary agent tank 3.3 contains the auxiliary tracer. The main agent tank 3.1 is connected to the main agent pump 3.2, and the auxiliary agent tank 3.3 is connected to the auxiliary agent pump 3.4.

[0075] The main tracer is a sulfonated rhodamine B derivative solution with a concentration of 0.8 g / L and a pH of 7.2. The main agent pump 3.2 uses a ceramic plunger with a flow accuracy of ±2 mL / s and a flow rate of 10~100 mL / min.

[0076] The auxiliary tracer is a suspension of nano zinc oxide catalyst with a concentration of 0.2 g / L and a particle size of 50 nm. The auxiliary pump 3.4 uses a PTFE-coated plunger to prevent crystallization, and its flow accuracy is ±1 mL / s, with a flow rate of 2~20 mL / min.

[0077] The mixing nozzle includes a Y-type mixer 3.5 and a nozzle 3.6. The Y-type mixer 3.5 includes a first pipe, a second pipe, and a mixing pipe. The first pipe and the second pipe are respectively connected to the mixing pipe, and the mixing pipe is connected to the nozzle 3.6. The first pipe and the second pipe are respectively connected to the main agent pump 3.2 and the auxiliary agent pump 3.4, so that the main tracer and the auxiliary tracer enter the mixing pipe through the first pipe and the second pipe, respectively, and are sprayed out through the nozzle 3.6.

[0078] The Y-type mixer 3.5 mentioned above has a mixing efficiency of >95%. The nozzle with the appropriate angle can be replaced according to the pipe diameter. For example, the common pipe diameter DN300 is equipped with a 30° nozzle, DN800 is equipped with a 65° nozzle, and DN1200 is equipped with a 110° nozzle.

[0079] In use, the intelligent injection module 3 is placed on the ground near the wellhead of the upstream inspection well of the pipe section to be inspected. The mixing pipeline is laid downwards from the wellhead and fixed to the well wall. The nozzle 3.6 at the end of the mixing pipeline is submerged below the water surface in the pipeline, and the angle is adjusted so that its outlet direction is basically consistent with the direction of water flow into the pipeline. After starting the main agent pump 3.2 and the auxiliary agent pump 3.4, the tracer is directly injected into the high-speed flowing water.

[0080] The intelligent injection module 3 uses double-walled insulated hoses for all liquid delivery. The inner layer of the hose is coated with PTFE for corrosion protection, and the outer layer is EPDM insulation material. It is connected to the nozzle 3.6 and the temperature is controlled throughout (25±2℃) to prevent the agent from deteriorating.

[0081] The tracer is a mixture of the main tracer and the auxiliary tracer.

[0082] Based on the above detection system, this invention discloses a method for accurately locating leaks in drainage pipes based on the concentration gradient colorimetric principle, comprising the following steps: S1. Fix a distributor 2 connected to a color-developing strip 1 in the upstream inspection well of the pipeline. Make the distributor 2 spiral forward along the central axis of the pipeline and continuously release the color-developing strip 1 in this process, so that the color-developing strip 1 is radially and tightly pressed and fixedly attached to the inspection area of ​​the inner wall of the pipeline, and is laid in a spiral trajectory along the central axis of the pipeline until the distributor 2 reaches the downstream inspection well of the pipeline.

[0083] Specifically, the color developing tape 1 is pre-wound onto a reel placed on the ground, with its free end entering the distributor 2. The free end of the color developing tape 1 is pulled out and sequentially passed through the first guide block 2.1, the second guide block 2.10, and the third guide block 2.11, guiding the free end of the color developing tape 1 from the horizontal direction to the radial direction, and then adhering it to a pressure roller 2.7.

[0084] Fix the distributor 2 in the inspection well upstream of the leaking pipe, and adjust the tilt angle of the traveling wheels 2.6 to 5°~25°. Start the system; the power supply 2.1 drives the motor 2.13 to rotate the drive connecting shaft 2.5. The drive connecting shaft 2.5 is rigidly connected to the rotating frame, causing the entire rotating frame to start rotating at a uniform speed. As the rotating frame rotates, the traveling wheels 2.6, due to their contact with the inner wall of the pipe and their tilt angle, generate an axial force under the action of friction. This force propels the entire distributor 2 forward in a spiral motion along the pipe. Simultaneously, the rotational motion drives the reel to unwind, and the developing tape 1 is continuously pulled out.

[0085] The pulled-out color developing strip 1 is guided by the guide block system and is radially and tightly pressed against the inner wall of the pipe at the pressure roller 2.7.

[0086] S2. The intelligent injection module 3 is used to continuously inject tracer upstream of the pipeline. The tracer is a mixture of main tracer and auxiliary tracer.

[0087] Specifically, tracer is first continuously injected into the pipeline, i.e. into the upstream inspection well and the water flow at the pipeline inlet, for 5 minutes at a flow rate of 80 mL / min, with the flow rate ratio of the main agent pump 3.2 and the auxiliary agent pump 3.4 being 4:1; then, 100 mL of the main tracer is injected into the pipeline every 1 minute at a concentration of 0.8 g / L for 25 minutes.

[0088] Preferably, the detection effect is best when the water temperature inside the pipe is 35~40 ℃ and the flow velocity is ≥3 m / s. This is because as the temperature increases, the diffusion and adsorption rate of sulfonated rhodamine B molecules into the fiber pores accelerates, leading to an increase in dye molecule enrichment per unit area, thus resulting in a change in color intensity. When there is a leak in the pipe, the seepage flow rate increases, the flow velocity at the leak point increases, and the combined effect of increased temperature and mass transfer rate increases. The turbulent energy at the leak point thins the diffusion boundary layer, reducing mass transfer resistance. The viscosity of wastewater is temperature-sensitive; as the temperature increases, the viscosity decreases, the fluid resistance decreases, the mass transfer rate of sulfonated rhodamine B increases, and thus the color intensity improves.

[0089] In the aforementioned pre-injection stage, a tracer is injected into the pipeline to establish a baseline concentration in the turbulent flow inside the pipeline. Then, in the pulse enhancement stage, a main tracer is injected into the pipeline in the form of a high-concentration pulse to enhance the adsorption of the leak point.

[0090] S3. Color band 1 captures the tracer and activates the color reaction in the wastewater environment, thereby forming a color intensity gradient along the length of color band 1 corresponding to the pipeline leakage point. The color intensity gradient is positively correlated with the pipeline leakage flow rate.

[0091] The fiber unit of color band 1 captures the tracer through the synergistic effect of chemical adsorption and thermochromic enhancement. The surface of the quaternary ammonium salt modified fiber generates strong electrostatic adsorption. Nano zinc oxide activates the thermocatalytic color reaction in the wastewater environment, forming a color intensity gradient along the length of color band 1. The color intensity is positively correlated with the infiltration flow rate.

[0092] S4. After separating the color developing band 1 from the distributor 2, peel the color developing band 1 off the inner wall of the pipe at a constant speed from the starting end of the color developing band 1 along the opposite direction of its layout and recover it. Then, use a colorimeter to continuously scan along the recovered color developing band 1 to obtain the color intensity. Based on the color intensity and the position information of the color developing band 1, determine the pipe leakage point and leakage intensity.

[0093] Further, the distributor 2 located in the downstream inspection well is lifted to the ground, and the color-developing strip 1 is peeled off from the distributor 2; at the upstream inspection well, from the starting end of the color-developing strip 1, the color-developing strip 1 is peeled off from the inner wall of the pipe and pulled out in the opposite direction of its laying direction; when the color-developing strip 1 is pulled out, a cooling medium with a temperature lower than the preset temperature of the memory skeleton 1.2 is introduced into the pipe to soften the memory skeleton 1.2; Specifically, the distributor 2, located in the downstream inspection well, is lifted to the ground. The color developing tape 1 is peeled off from the pressure roller 2.7 of the distributor 2 and completely extracted from the third guide block 2.11, the second guide block 2.10, and the first guide block 2.9 in the opposite direction to its installation, thus completely separating the color developing tape 1 from the distributor 2. At the upstream inspection well, the starting end of the color developing tape 1 is dragged, and the entire tape 1 is peeled off from the inner wall of the pipe and pulled out of the pipe at a uniform speed in the opposite direction to its installation. To ensure smooth peeling and protect the tape, cooling air with a temperature lower than the phase change point of the memory skeleton 1.2 (e.g., ≤25℃) can be blown into the pipe while dragging, softening the memory skeleton 1.2 and reducing its adhesion to the pipe wall.

[0094] In some alternative embodiments, a manual winch is used, with the end of the color developing tape 1 connected by a rope. Every 2 m of color developing tape 1 is pulled out, a fan with an outlet air temperature ≤25℃ is used to blow and cool the memory frame 1.2 to soften it, and the color developing tape 1 is slowly and evenly pulled out of the pipe.

[0095] A portable colorimeter is used to scan colorimetric band 1, and its color intensity is quantified by a colorimetric model. The section where the color intensity changes beyond the preset value is automatically identified as a valid leakage signal. The colorimetric location information of colorimetric band 1 corresponding to the valid leakage signal is obtained by the position encoding of the colorimetric label, thereby determining the location and intensity of pipeline leakage.

[0096] Specifically, a portable colorimeter is used to scan colorimetric band 1, and its color intensity is quantified through a colorimetric model. The section where the color intensity changes beyond the preset value is automatically identified as an effective leakage signal. The effective leakage signal is combined with the colorimetric location information of colorimetric band 1 to accurately determine the leakage coordinates and degree in the pipeline.

[0097] During testing, the portable colorimeter is moved along the colorimetric band, and a set of data is recorded at certain intervals. The interval distance is usually adjusted according to the actual situation.

[0098] The portable colorimeter integrates a positioning decoder and a laser rangefinder. The positioning decoder is integrated inside the scanning handle of the portable colorimeter and can read the color label to bind the colorimetric data with the pipeline position coordinates. The laser rangefinder is installed at the bottom of the handle, so that the portable colorimeter can record the distance between the scanning point and the nearest color label in real time when it moves along the color band 1.

[0099] Among them, the positioning decoder is a miniaturized embedded RFID reader / writer; the laser ranging wheel is a high-precision photoelectric encoding wheel, both of which are commercially available modules.

[0100] The colorimetric model is the CIE Lab* color space, with a preset value of ΔE≥5; colorimetric positioning information is obtained by reading the colorimetric labels, and the spatial resolution of the colorimetric positioning information is ±5 cm.

[0101] The aforementioned spatial resolution mainly depends on the accuracy of the laser rangefinder wheel and the accuracy of the leakage point compensation algorithm, and can be adjusted and set according to these factors.

[0102] The portable colorimeter has a spectral response range covering the visible light band, which is 380 nm to 850 nm.

[0103] The aforementioned portable colorimeter features dual CMOS sensors: a visible light channel and a near-infrared channel. The visible light channel captures the color characteristics of the colorimetric reagent, with a spectral range of 380–650 nm and a dominant wavelength of 630 nm. The near-infrared channel penetrates highly turbid wastewater, with a spectral range of 780–850 nm. Dual-wavelength detection eliminates the influence of suspended solids scattering. During detection, an integrating sphere illumination system surrounds the CMOS sensor, with a uniformity >98%, ensuring uniform illumination.

[0104] The specific analysis process for detection information includes: (1) Preprocessing of the original signal and calculation of turbidity compensation: I λraw = I λ - k λ x I 850nm ; Among them, I λraw The reflected intensity after turbidity compensation for wavelength; I λ The wavelength reflection signal is represented by λ, which is 630nm, 550nm, and 450nm, respectively. These are the values ​​detected by the photosensitive sensor, where 630nm is the characteristic absorption peak of the color developer, 550nm is the optimal brightness response, and 450nm is the yellow-blue hue boundary. 850nm The reflected signal is at a reference wavelength of 850nm, and the value is detected by the near-infrared sensor; k λ The wavelength-specific coefficients were determined through calibration experiments. The wavelength-specific coefficients for 630nm, 550nm, and 450nm were 0.78, 0.75, and 0.82, respectively, yielding I0. 450raw I 550raw and I 630raw .

[0105] (2) Convert L*a*b* chromaticity values:

[0106] Where L* represents lightness; a* represents red-green hue; b* represents yellow-blue hue; X, Y, and Z are CIE XYZ tristimulus values; X nY n Z n This corresponds to the standard whiteboard reference value.

[0107] (3) The color difference value ΔE is calculated using the following formula:

[0108] Where 1 represents the upstream detection data point; 2 represents the adjacent downstream detection data point; the interval between two adjacent detection data points is 1 cm. A valid signal is defined as ΔE ≥ 5.

[0109] (4) The process of determining the location of the pipeline leak point in colorimetric zone 1 includes: The handheld colorimeter scanner integrates a positioning decoder and a laser rangefinder. The positioning decoder reads the color labels of the colorimeter unit and binds the colorimetric data to the pipe position coordinates. The laser rangefinder records the distance between the scanning point and the nearest color label in real time.

[0110] Actual location of the leak point = location of the color-coded label + (displacement of the measuring wheel × compensation coefficient for the helix angle); The displacement of the measuring wheel is the distance it rolls linearly from the previous color label, measured by the laser measuring wheel, and the unit is mm.

[0111] Specifically, the rangefinder wheel displacement refers to the straight-line distance the scanner travels on the color-changing tape from the most recently read position of the color-changing label to the current scanning point. For example, when it passes a color-changing label (e.g., number N), the system records: "Currently at the absolute position of label N," and simultaneously resets the laser rangefinder wheel's counter to zero. The scanner continues to move forward, and the rangefinder wheel begins to accumulate the distance it has moved. For instance, after moving forward 30 cm and scanning a point with a strong ΔE, the system records the color-changing label number N and the rangefinder wheel displacement, i.e., 30 cm.

[0112]

[0113] P = πD·tanα Where k is the helix angle compensation coefficient; η is the slip ratio, which is usually taken as 0.85~0.95, as the actual pitch may be less than the theoretical value due to friction on the inner wall of the pipe; D is the inner diameter of the pipe in mm; P is the theoretical pitch; and α is the tilt angle of the laying device's traveling wheel.

[0114] Specifically, relying on color-developing units set at fixed length intervals, color-developing labels embedded in the middle area provide absolute coordinate reference points. The spacing between adjacent color-developing labels is fixed, and the color-developing band between two labels is continuous. However, the color-developing point corresponding to the pipeline leak may be located at any location, not just at the label's location. Therefore, a ranging wheel is set up to accurately locate the specific position between the color-developing labels, facilitating precise measurement of the distance between the color-developing point located in the area between the color-developing labels and the color-developing label serving as the reference point.

[0115] Methods for determining the specific coordinates of a pipeline leak include: (1) Establishing a starting point mapping at the start of deployment: At the location where the deployer 2 is about to enter the pipeline, i.e., inside the upstream inspection well, the operator manually reads and records the ID of the first RFID tag pressed onto the pipe wall using a handheld device. At the same time, this ID is bound to the center station number of the upstream inspection well. This binding point is the "coordinate origin" of the entire positioning system.

[0116] (2) Synchronous recording of the deployment process: During the spiral advance of the deployer 2, its built-in encoder or odometer will record the axial distance (S) of the deployer 2 itself. An RFID reading antenna is installed at the front end of the deployer. The antenna sensing center should be located on the path of the color-developing tape 1 after it passes through the third guide block 2.11 and before it enters the wedge-shaped pressing area formed by the pressing roller 2.7 and the tube wall. During the deployment process, whenever a color-developing tag (RFID) passes through a fixed reading point on the deployer, the system will automatically trigger and synchronously record the "unique ID of the tag" and the "current axial odometer reading Stag of the deployer".

[0117] (3) Leakage point location: Locate the axial distance S that the deployer 2 has traveled when tag N is released from the deployment record. N Calculate the total length L of the leakage point on the colorimetric strip. leak for: L leak =S N + d∙k.

[0118] Among them, S N d is the axial distance traveled by the deployer when the Nth color-coded label is released and pressed against the pipe wall, in meters; d is the displacement of the measuring wheel, in meters; k is the spiral deployment helix angle compensation coefficient (dimensionless).

[0119] By combining the color difference data ΔE with the actual location information of the leak point, the location and intensity of the pipeline leak can be accurately determined.

[0120] Example 1: Precise location and detection of leaks in DN800 rainwater pipes An inspection was conducted on a DN800 rainwater pipe in a certain city, revealing a leak with a large amount of sewage entering. The leak is located between inspection manholes Y01 (chainage K2+345) and Y02 (chainage K2+400), but the exact location of the leak cannot be determined. When using the aforementioned detection system to pinpoint the leak, the average flow velocity of the water inside the pipe reached 4 m / s.

[0121] S1: Color-rendering tape deployment: Install color-rendering tape deployer 2 at Y01, upstream inspection well of the rainwater pipe.

[0122] Pull out the free end of the colorimetric strip 1 and insert it sequentially into the first guide block 2.9, the second guide block 2.10, and the third guide block 2.11. Fix the distributor 2 in the inspection well upstream of the leaking pipe, adjust the inclination angle α of the traveling wheel 2.6 to 12°, the slip ratio η to 0.90, and the pipe diameter D to 800 mm. The calculated helix angle compensation coefficient is approximately 0.9821.

[0123] The system is started, and the drive motor 2.13 drives the drive connecting shaft 2.5 to rotate. The drive connecting shaft 2.5 is rigidly connected to the rotating frame, causing the entire rotating frame to begin rotating at a uniform speed. As the rotating frame rotates, the traveling wheels 2.6, due to their contact with the inner wall of the pipe and their own axle having an inclination angle, generate an axial force under the action of friction, thus propelling the entire distributor 2 forward in a spiral motion along the pipe. Simultaneously, the rotational motion drives the internal reel to unwind, continuously pulling out the color developing tape 1. The pulled-out color developing tape 1, guided by the guide block system, is radially and tightly pressed against the inner wall of the pipe at the pressure roller 2.7. The machine stops after reaching the next inspection well.

[0124] The color developing band 1 consists of two layers of polyacrylonitrile-based carbon fiber, with the outer layer having a porosity of 70% and the inner layer having a porosity of 65%. The memory skeleton 1.2 is made of nickel-titanium alloy wire with a diameter of 0.3 mm, located between the inner and outer fibers. The alloy wire undergoes a phase transition at 37℃, which improves the adhesion of the color developing band to the wall. A color developing unit is set at 50 cm intervals along the length of the color developing band 1. A color developing label is placed in the middle of each unit, embedded between the inner and outer fibers, with a spatial resolution of ±5 cm.

[0125] S2: Pulse injection: Connect the intelligent injection module 3 to the inspection well Y01 upstream of the rainwater pipe.

[0126] Pre-injection stage: Start the main agent pump 3.2 and the auxiliary agent pump 3.4 simultaneously and continuously inject the main tracer and auxiliary tracer for 5 minutes at a flow rate of 80 mL / min, with the main and auxiliary agent flow rates being 4:1, to establish the baseline concentration.

[0127] Pulse enhancement phase: Only activate the main agent pump 3.2 to inject a high-concentration pulse at a frequency of 1 pulse / minute, i.e., 1.5 g / L of main agent, 100 mL per injection, to enhance adsorption at leakage points. The pulse enhancement phase lasts for 25 minutes. Select a 65° nozzle suitable for DN800 pipe diameter.

[0128] S3: Gradient color development and adsorption.

[0129] (1) Color development kinetics: Quaternary ammonium salt groups are grafted onto the surface of the outer fiber, and negatively charged sulfonated rhodamine B molecules are captured by Coulomb force. Strong electrostatic adsorption is generated on the surface of the quaternary ammonium salt modified fiber. The nano zinc oxide generates heat through friction in the turbulent environment, and the sulfonated rhodamine B undergoes a color development reaction through thermal catalysis. The color development intensity is positively correlated with the permeation flow rate. That is, as the permeation flow rate in the pipeline increases, the amount of sulfonated rhodamine adsorbed by the color band increases, and the catalytic temperature also increases, which increases the color development intensity.

[0130] (2) Gradient formation verification: Color band 1 forms a significant color difference gradient downstream of the leakage point, and the color intensity ΔE of the leakage point unit is significantly higher than that of the upstream adjacent unit.

[0131] S4: Recovery and analysis of colorimetric band 1.

[0132] (1) Retrieval of color development tape 1: Use a manual winch to connect the end of color development tape 1 with a rope. For every 2 m of color development tape 1 pulled out, use a fan at a temperature below 25°C to blow and cool the memory frame 1.2 to soften it. Slowly and evenly pull the color development tape 1 out of the pipe.

[0133] (2) Quantitative analysis of colorimetry: The colorimetric strip 1 recovered from the pipeline was scanned on-site using a handheld colorimeter. The colorimeter is a dual CMOS sensor, including a visible light channel and a near-infrared channel. The visible light channel captures the color characteristics of the colorimetric agent, with a spectral range of 380~650nm and a dominant wavelength of 630nm. The near-infrared channel penetrates high-turbidity wastewater, with a spectral range of 780~850nm. Dual-wavelength detection is used to eliminate the influence of suspended solids scattering. An integrating sphere illumination system surrounds the CMOS sensor to ensure uniform illumination.

[0134] The calculated location information is as follows: The mileage S of the second axis of the deployer when the 60th color display unit tag is read is... 60 =2345+29.93 = 2374.93m, corresponding to the approximate pipeline station: K2+374.93; the 61st color-coded label indicates the mileage S of the second axis of the deployer when it is read. 61 = S 60 +0.5345 = 2375.4675m, corresponding to the approximate pipeline station: K2+375.4675; color tag No. 62, the mileage S of the deployer axis when read. 62 = S 61+0.5345 = 2375.999m, corresponding to the approximate pipeline station number: K2+375.999.

[0135] During the recovery scanning phase, the portable colorimeter is used in Tag... 60 With Tag 62 Within the interval, three consecutive points A, B, and C with abnormal color intensity were detected. Point A has a ΔE = 12.5, and the nearest RFID tag is Tag. 60 The ranging wheel reading is 0.15m; at point B, ΔE = 15.2, the nearest RFID tag is Tag. 61 The ranging wheel reading is -0.1m; at point C, ΔE = 11.8, the nearest RFID tag is Tag. 61 The distance measuring wheel reading is 0.12m.

[0136] Calculate the pipe coordinates at point A: LA = S 60 +0.15*0.9821=2374.93+0.1473=2375.0773m, corresponding to pipeline station number K2+375.0773.

[0137] Calculate the pipe coordinates at point B: LB = S 61 +(-0.1)*0.9821=2375.4645+0.1473=2375.36629m, corresponding to pipeline station number K2+375.3663.

[0138] Calculate the pipe coordinates at point C: LC = S 61 +0.12*0.9821=2375.4645+0.17785=2375.58235m, corresponding to pipeline station number K2+375.5824.

[0139] Therefore, the color intensity ΔE value of point B is the largest, the pipeline station number is K2+375.366, and ΔE>10 for 3 consecutive units, so it is determined to be a first-level leakage point.

[0140] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

[0141] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. Technical details not described in detail in this invention can all be implemented using any existing technology in the art. In particular, all technical features not described in detail in this invention can be implemented using any existing technology.

Claims

1. A method for accurately locating leaks in drainage pipes based on the principle of concentration gradient color development, characterized in that, Includes the following steps: S1. Fix a distributor connected to a color-developing tape in the upstream inspection well of the pipeline, and make the distributor spiral forward along the central axis of the pipeline, while continuously releasing the color-developing tape in this process, so that the color-developing tape is radially and tightly pressed and fixedly attached to the detection area of ​​the inner wall of the pipeline, and is laid along the central axis of the pipeline in a spiral trajectory until the distributor reaches the downstream inspection well of the pipeline. S2. Continuously inject tracer upstream of the pipeline; S3. The color-developing band activates a color-developing reaction in a wastewater environment, thereby forming a color intensity gradient corresponding to the pipeline leakage point along the length of the color-developing band. The color intensity gradient is positively correlated with the pipeline leakage flow rate. S4. After separating the color-developing tape from the distributor, peel the color-developing tape off the inner wall of the pipe at a constant speed from the starting end of the color-developing tape along the opposite direction of its layout and collect it. Then, use a colorimeter to continuously scan along the collected color-developing tape to obtain the color intensity. Based on the color intensity and the position information of the color-developing tape, determine the leakage point and leakage intensity of the pipe.

2. The method for accurately locating leakage in drainage pipes based on the concentration gradient colorimetric principle according to claim 1, characterized in that, The deployer includes a power supply mechanism, a rotating frame, a drive mechanism, a rolling mechanism, and a guiding mechanism; The rotating frame includes a support base, a front plate, and a rear plate, with the front plate and the rear plate respectively connected to both ends of the support base; The drive mechanism includes a drive connecting shaft, a motor, and a coupling. The drive connecting shaft is axially inserted into the support base and fixedly connected to the support base. The front end of the drive connecting shaft passes through the bearing in the center of the front plate. The motor is connected to the drive connecting shaft via the coupling. The power supply mechanism includes a power source and wires, and the power source is connected to the motor through the wires; The rolling mechanism includes a plurality of rolling components, which are evenly distributed along the circumference of the support base and are arranged in parallel at intervals on the outside of the support base. The guiding mechanism includes at least one guiding block, each of which is disposed on the support base. Each guiding block has a guiding groove, through which the color developing tape passes, so that the color developing tape entering the distributor is guided to the outside of the rolling assembly and radially pressed into the inside of the pipe. The drive assembly drives the rotating frame to rotate radially at a uniform speed along the extension direction of the drive connection shaft, which in turn drives the rolling mechanism to rotate, thereby pushing the distributor to move forward spirally along the central axis of the pipeline. During this process, the rolling mechanism continuously releases the color developing strip, so that the color developing strip is radially and tightly pressed against the rolling assembly and fixedly attached to the detection area on the inner wall of the pipeline.

3. The method for accurately locating leakage in drainage pipes based on the concentration gradient colorimetric principle according to claim 2, characterized in that, The rolling mechanism includes a support arm, a traveling wheel, and a pressure roller; The support arm is evenly arranged along the circumference of the side of the support base and connected to the support base. The traveling wheel and the pressing roller are rotatably connected to the support arm. A plurality of traveling wheels are distributed along the circumference of the support arm, and a plurality of pressing rollers are arranged parallel and spaced apart on the support arm. The axle of the traveling wheel has an inclination angle relative to the vertical direction of the axle of the pressure roller, so that when the traveling wheel contacts the inner wall of the pipe, the inclination angle generates an axial force, thereby pushing the distributor to move forward spirally along the central axis of the pipe. The rolling assembly includes a first support arm, a second support arm, a first traveling wheel, a second traveling wheel, a first pressure roller, and a second pressure roller; The first support arm and the second support arm have the same structure, both being T-shaped structures, including a horizontal section and a vertical section, with the upper end of the vertical section connected to the lower middle part of the horizontal section; The first traveling wheel and the second traveling wheel are respectively rotatably connected to the upper side of the corresponding horizontal segment of the first support arm and the second support arm; The axles of the first traveling wheel and the second traveling wheel are arranged in parallel, and the axles of the first pressure roller and the second pressure roller are arranged in parallel. The first support arm and the second support arm are respectively connected to the opposite ends of the support base, and their corresponding lower ends of the vertical sections are respectively fixedly connected to the outer wall of the support base. The first pressure roller and the second pressure roller are rotatably connected between the first support arm and the second support arm, respectively. The two ends of the first pressure roller are respectively connected to one end of the corresponding horizontal segment of the first support arm and the second support arm, and the two ends of the second pressure roller are respectively connected to the other end of the corresponding horizontal segment of the first support arm and the second support arm, so that the free end of the color developing strip is guided by the guiding mechanism and is radially and tightly pressed and fixedly attached to the detection area of ​​the inner wall of the pipe at any of the pressure rollers.

4. The method for accurately locating leakage in drainage pipes based on the concentration gradient colorimetric principle according to claim 3, characterized in that, The guiding mechanism includes a first guiding block, a second guiding block, and a third guiding block; The first guide block, the second guide block and the third guide block are all rectangular block structures and are distributed sequentially along the axial direction of the support base. They are respectively provided with a first guide groove, a second guide groove and a third guide groove. The first guide groove, the second guide groove and the third guide groove are all provided with rotatable guide wheels inside. The first guide block is installed on the inner side of the rear plate facing the support base and is fixedly connected to the rear plate. The extension direction of the first guide groove is parallel to the axial direction of the distributor, and its inlet is directly opposite to the starting end of the color developing tape, so that the outlet direction of the color developing tape passing through the outlet of the first guide groove is parallel to the axial direction of the distributor. The second guide block is fixedly connected to the outer side of the middle part of the support base by any of the support arms and is located between the support base and the walking wheel. The inlet of the second guide groove receives the color-developing strip that passes through the first guide block and deflects its traveling direction from the axial direction of the distributor. The third guide block is installed on the inner side of the front plate facing the support base and is fixedly connected to the front plate. The inlet of the third guide groove receives the color developing strip that passes through the second guide block and guides its travel direction to the radial direction of the distributor. The outlet of the third guide groove is aligned with the tangent point of any of the pressure rollers and the inner wall of the pipe. The central axis of the third guide groove is perpendicular to the central axis of the distributor.

5. The method for accurately locating leakage in drainage pipes based on the concentration gradient colorimetric principle according to claim 1, characterized in that, The color developing strip includes a first fiber layer, a second fiber layer, a memory skeleton, and several color developing labels; The memory skeleton is disposed between the first fiber layer and the second fiber layer. The memory skeleton undergoes a phase change at a preset temperature so that the first fiber layer located inside the color band is tightly attached to the inner wall of the pipe. A number of color-developing units are arranged sequentially at a fixed length distance along the length direction of the color-developing strip, and the color-developing labels are correspondingly arranged in the middle area of ​​the color-developing units and embedded between the first fiber layer and the second fiber layer.

6. The method for accurately locating leakage in drainage pipes based on the concentration gradient colorimetric principle according to claim 5, characterized in that, The surface of the second fiber layer is grafted with quaternary ammonium salt groups; The grafting method for the quaternary ammonium salt group includes the following steps: The second fiber layer was pretreated with 5% NaOH solution at 60°C, and then immersed in an ethanol solution containing 2-5 wt% 3-aminopropyltriethoxysilane for 2-4 h at room temperature; then the second fiber layer was immersed in a hexadecyltrimethylammonium bromide solution and reacted at 60-80°C for 4-6 h; then the second fiber layer was thoroughly washed with deionized water and vacuum dried at 50°C to constant weight. The grafting amount of the quaternary ammonium salt is 0.1~0.5 mmol / g, and the density of the quaternary ammonium salt groups is 0.5~2.5 μmol / cm².

7. The method for accurately locating leakage in drainage pipes based on the concentration gradient colorimetric principle according to claim 1, characterized in that, In step S2, a smart injection module is used to continuously inject tracer upstream of the pipeline. The tracer is a mixture of main tracer and auxiliary tracer. The intelligent injection module includes a dual-plunger pump assembly and a mixing injection head; The dual-plunger pump assembly includes a main agent tank, a main agent pump, an auxiliary agent tank, and an auxiliary agent pump. The main agent tank contains a main tracer, the auxiliary agent tank contains an auxiliary tracer, the main agent tank is connected to the main agent pump, and the auxiliary agent tank is connected to the auxiliary agent pump. The mixing nozzle includes a Y-type mixer and a nozzle, wherein the Y-type mixer includes a first pipe, a second pipe, and a mixing pipe, the first pipe and the second pipe are respectively connected to the mixing pipe, and the mixing pipe is connected to the nozzle; the first pipe and the second pipe are respectively connected to the main agent pump and the auxiliary agent pump, so that the main tracer and the auxiliary tracer enter the mixing pipe through the first pipe and the second pipe respectively, and are sprayed out through the nozzle.

8. The method for accurately locating leakage in drainage pipes based on the concentration gradient colorimetric principle according to claim 7, characterized in that, The main tracer is a sulfonated rhodamine B derivative solution with a concentration of 0.8 g / L and a pH of 7.

2. The main tracer pump has a flow rate accuracy of ±2 mL / s and a flow rate of 10~100 mL / min. The auxiliary tracer is a nano zinc oxide catalyst suspension with a concentration of 0.2 g / L, the nano zinc oxide has a particle size of 50 nm, and the auxiliary agent pump has a flow accuracy of ±1 mL / s and a flow rate of 2~20 mL / min. In step S2, the tracer is first continuously injected upstream of the pipeline for 5 minutes at a flow rate of 80 mL / min, wherein the flow ratio of the main agent pump and the auxiliary agent pump is 4:

1. Then, 100 mL of the main tracer was injected into the pipeline every 1 minute, the concentration of the main tracer being 0.8 g / L, for 25 minutes.

9. The method for accurately locating leakage in drainage pipes based on the concentration gradient colorimetric principle according to claim 5, characterized in that, In step S4, the distributor located in the downstream inspection well is lifted to the ground, and the color-developing strip is peeled off from the distributor; at the upstream inspection well, the color-developing strip is peeled off from the inner wall of the pipe from the starting end of the color-developing strip in the opposite direction to its laying direction and pulled out; when the color-developing strip is pulled out, a cooling medium with a temperature lower than the preset temperature is introduced into the pipe to soften the memory skeleton; A portable colorimeter is used to scan the colorimetric band, and its color intensity is quantified by a colorimetric model. The section where the color intensity changes beyond a preset value is automatically identified as a valid leakage signal. The colorimetric location information of the colorimetric band corresponding to the valid leakage signal is obtained by the position encoding of the colorimetric label, thereby determining the location and intensity of the pipeline leakage.

10. The method for accurately locating leakage in drainage pipes based on the concentration gradient colorimetric principle according to claim 9, characterized in that, The colorimetric model is the CIE Lab* color space, and the preset value is ΔE≥5; The colorimetric positioning information is obtained by reading the colorimetric label, and the spatial resolution of the colorimetric positioning information is ±5 cm. The portable colorimeter has a spectral response range covering the visible light band, which is 380 nm to 850 nm.

Images