JP7397516B2 - Method for estimating internal corrosion locations of sewage pipes and equipment for detecting corrosion locations - Google Patents

Description

The present invention relates to a technique for predicting and identifying corrosion points on the inner surface of a sewage pipe such as a sewage pressure transmission pipe.

There are two types of sewage pipe systems: a gravity flow system that uses differences in ground elevation, and a pressure pipe system that uses pressure from a pump. The inner surface is susceptible to corrosion due to the effects of hydrogen sulfide generated from sewage.

First, to explain the corrosion mechanism caused by hydrogen sulfide on the inner surface of mortar-lined sewer pipes with reference to Figure 7, when the inside of closed pipe A becomes an anaerobic environment (an environment lacking in oxygen), sulfate in sewage B becomes (SO42-) is reduced by sulfate-reducing bacteria to generate hydrogen sulfide (H2S) (Figure 7a). When the sewage B comes into contact with the air layer C, this hydrogen sulfide generated in the sewage B is diffused into the air layer C, dissolves in the water adhering to the inner surface E of the mortar lining, and is concentrated. Here, if a sufficient aerobic environment (an environment with oxygen) occurs, hydrogen sulfide adhering to the inner surface E of the mortar lining of the sewer pipe D through moisture is oxidized by sulfur-oxidizing bacteria, and sulfuric acid ( H2SO4) is generated, and the mortar lining inner surface E is corroded by this sulfuric acid (Fig. 7b).

In the sewage pressure transmission pipe F shown in Fig. 8, for example, if sewage B flows in the sewage pressure transmission pipe F in a full state (see arrow) and is in an anaerobic state, hydrogen sulfide is generated in the sewage B. Since there is no air pocket or large air pocket in the upper part of the sewage pressure pipe F, hydrogen sulfide is not oxidized by sulfur-oxidizing bacteria and sulfuric acid is not generated, and in this range, the inner surface of the mortar lining of the sewage pressure pipe F G is not corroded (Fig. 8a). However, for example, if a space I is created above the convex portion H of the sewage pressure pipe F, this space I becomes an air pocket J due to the air flowing in from the air valve V. Hydrogen sulfide is generated in the sewage B at the point where the pipe is full, but this hydrogen sulfide is carried to the air pocket J, is dissipated into the air pocket J, and adheres to the inner surface G of the mortar lining of the sewage pressure pipe F ( adhesion via moisture). Then, sulfuric acid is generated from hydrogen sulfide adhering to the inner surface G of the mortar lining of the sewage pressure pipe F, and corrosion occurs in the area indicated by the broken line K (FIG. 8b).

By the way, the degree of corrosion on the inner surface of the sewage pressure transmission pipe can be confirmed, for example, by attaching an ultrasonic thickness gauge M to the outer surface of the sewage pressure transmission pipe and measuring the thickness of the pipe wall, as shown in FIG. can. That is, if the pipe thickness N is thinner than the pipe thickness of other parts, corrosion progresses depending on the degree of thinness. However, carrying out this measurement over the entire length of the sewage pressure transmission pipe is not efficient because the entire length of the sewage pressure transmission pipe must be excavated. Furthermore, since the pressure pump must be stopped for a long period of time during the survey work, measurement over the entire length of the pipe is undesirable from the standpoint of operating the sewage treatment facility. Therefore, as described in Patent Document 1, for example, the location where air pockets occur in the sewage pressure transmission pipe is investigated, and it is estimated that the corrosion of the sewage pressure transmission pipe is progressing at the location where the air pocket occurs, and the air is removed. It has been proposed to actually conduct a corrosion investigation focusing on the locations where pooling occurs.

Japanese Patent Application Publication No. 2001-254434

The investigation of the location where air pockets occur in Patent Document 1 is carried out using a longitudinal cross-sectional view of the sewage pressure transmission pipe and a hydraulic gradient line, but the actual sewage pressure transmission pipe is not necessarily laid according to the piping drawing. There are many cases where reliability is lacking, as there is no guarantee that there will be any.

Therefore, the present invention provides a method for reliably investigating the locations where air pockets occur in sewage pressure pipes, and based on the results of this investigation, highly reliable estimation of corrosion locations on the inner surface of the sewage pressure pipelines, and a method for detecting corrosion locations using this method. The purpose is to provide equipment.

To achieve this objective, the present invention provides a method for estimating internal corrosion locations of a sewage pipe, which is a method for estimating internal corrosion locations of a sewage pipe in which a pumping station with a pump is installed. preparing a submersible and above-water mobile body having a submersible and above-water body, and while the pump is operating, the submersible and above-water moving body is carried by the flow of sewage in the sewage pipe and moves downstream in the sewage pipe; Corroded areas on the inner surface of the sewage pipe are estimated based on the position of the liquid level of the sewage detected by the liquid level detection sensor during the movement of the underwater and waterborne vehicles within the sewage pipe. Here, the position of the sewage liquid level detected by the liquid level detection sensor can be configured to be specified by a position detection sensor that is provided on the underwater and waterborne vehicle and detects the moving position of the underwater and waterborne vehicle. .

The underwater and waterborne vehicles further have a photographing camera, and the position of the sewage liquid level detected by the liquid level detection sensor as well as the position of the sewage water level within the sewage pipe are captured by the photographing camera while the underwater and waterborne vehicle is moving within the sewage pipe. Based on the photographic results, it is possible to estimate the locations of internal corrosion in the sewer pipe. With this configuration, it is possible to more accurately estimate the location of corrosion on the inner surface of the sewage pipe.

Moreover, the corrosion location detection device of the present invention to achieve this object is a corrosion location detection device for estimating the interior corrosion location of a sewage pipe in which a pumping station having a pump is installed. A submersible and above-water mobile body that is thrown into the sewage in the sewage pipe during operation and moves downstream in the sewage pipe along with the flow of the sewage; It is equipped with a liquid level detection sensor. Furthermore, position detection sensors can also be provided on underwater and on-water moving bodies. The underwater and waterborne vehicles can be configured to have a storage means, and the detection result of the liquid level detection sensor is stored in the storage means in association with the detection result of the position detection sensor.

The underwater and waterborne vehicles can also be equipped with a photographing camera, and the detection results of the liquid level detection sensor and the photographing results of the photographing camera can be stored in the storage means in association with the detection results of the position detection sensor.

By using the method for estimating the internal corrosion location of a sewage pipe or the corrosion location detection device of the present invention, the internal corrosion location of the sewage pipe can be identified with high accuracy.

1 is a diagram showing the configuration of a corrosion location detection device according to the present invention. It is a figure which shows the case where a corrosion location detection apparatus detects the liquid level of sewage. It is a figure which shows the example of a change of the arrangement|positioning aspect of a liquid level detection sensor. It is a figure explaining the case where an air pocket in a sewer pipe is inspected using a corrosion place detection device when a pump is operating. It is a figure explaining the state when a corrosion place detection device moves in the inside of a sewer pipe. FIG. 2 is a diagram illustrating a case of estimating a corroded location in a sewage pipe. It is a figure explaining the corrosion mechanism by hydrogen sulfide of the inner surface of a sewer pipe. It is a figure which shows the case where corrosion occurs on the inner surface of a sewage pressure pipe. It is a figure which shows the case where the degree of corrosion of an inner surface is confirmed from the outer surface of a sewage pressure transmission pipe. FIG. 3 is a diagram showing the configuration of another corrosion location detection device according to the present invention. FIG. 3 is a cross-sectional view of the front cover portion. FIG. 3 is a cross-sectional view of the rear cover portion. FIG. 3 is a sectional view of the rear side of the case.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

First, the configuration of a corrosion location detection device according to the present invention will be explained with reference to FIG.

Corrosion point detection device 1 (underwater and waterborne moving objects) includes a resin case 3 (underwater and waterborne moving objects), a detector 5 sealed in this case 3, and a power supply to this detector 5. It includes a battery 7 for supplying power, and a measurement push button switch 9 that is provided in the case 3 and turns on and off the supply of power from the battery 7 to the detector 5. The case 3 includes a cylindrical case body 11, and a semispherical or semispheroidal front cover 13 and rear cover 15 that are removably attached to the front and rear ends of the case body 11, respectively. The detector 5 includes a pair of liquid level detection sensors 17 arranged to face the inner surface of the case body 11 and detects the liquid level of sewage in the sewage pipe, and a corrosion point detector 1. Detection from the 3-axis acceleration sensor 19 that detects the moving distance, the 3-axis gyro sensor 21 that detects the moving direction of the corrosion location detector 1, the liquid level detection sensor 17, the 3-axis acceleration sensor 19, and the 3-axis gyro sensor 21 Upon receiving the signal, the information on the presence or absence of the sewage level detection is correlated with the movement position information of the corrosion location detection device 1 within the sewage pipe, and is stored in a storage medium 25 such as a memory card that is removably inserted into the holder 23. It has a control unit 27 for storing information. The front cover 13 and the rear cover 15 are each screwed to the end of the case body 11 via a gasket, for example, and the measurement push button switch 9 is provided at the rear of the case body 11. It is configured so that it can be removed and turned on and off.

The corrosion location detection device 1 is configured to move downstream in the sewage pipe along with the flow of sewage in the sewage pipe. The specific gravity is adjusted to about 0.8 to 0.9, which is less than 1, so that it floats on the sewage surface.

Each liquid level detection sensor 17 includes, for example, a liquid level detection capacitor 29, and the capacitance of this liquid level detection capacitor 29 changes as the dielectric constant of the outside of the case body 11 at the mounting position changes. It is configured. Therefore, as shown in FIG. 2, when the corrosion detection device 1 approaches a position where the sewage 33 flowing through the sewage pipe 31 has a free water surface 35 and floats on the sewage 33, the liquid level detection sensor 17 (one of the liquid level detection The sensor 17) is located in the sewage 33 on or above the free water surface 35, and the capacitance of the liquid level detection capacitor 29 of one liquid level detection sensor 17 is affected by the dielectric constant of the air. By detecting this capacitance, it is possible to detect the presence or absence of air pockets. The liquid level detection sensor 17 detects the air pocket even if the air pocket is in a small space and the portion of the corrosion point detection device 1 protruding above the free water surface 35 of the sewage 33 is small. Alternatively, it is arranged within the case 3 so that the free water surface 35 can be detected with high accuracy.

In addition, as shown in FIG. 3, in order to improve the accuracy of liquid level detection, four (FIG. 3a) or six (FIG. 3b) liquid level detection sensors 17 may be provided at equal intervals in the circumferential direction.

In both the case of FIG. 3a and the case of FIG. 3b, for example, a pair of liquid level detection capacitors 29 can be arranged in each liquid level detection sensor 17 so as to open outward.

FIGS. 4 and 5 are diagrams illustrating a case where the corrosion location detection device 1 is used to inspect the corrosion state of the inner surface of a sewage pipe 31 having a pumping station.

When the pressure pump P of the pump station 37 is in operation and the sewage 33 is being pumped, the measurement push button switch 9 is turned on to insert the corrosion location detector 1 into the sewage pipe 31. The flow rate of the sewage 33 being pumped is constant or approximately constant, for example, from 0.6 m/sec to 3.0 m/sec. When inserting the corrosion spot detector 1 into the sewage pipe 31, remove the rear cover 15 from the case body 11, turn on the measurement push button switch 9, and then insert the rear cover 15 back into the case body 11. Make sure to install it. When the corrosion location detection device 1 is introduced into the sewage pipe 31, the corrosion location detection device 1 rides on the flow of the sewage water 33 and moves downstream (toward the upper right side in FIG. 4) in the sewage pipe 31. Since the sewage water 33 always flows through the sewage pipe 31 in a full state from L1 to L4, there is no free water surface anywhere from L1 to L4, and no air pockets are generated. Therefore, since the corrosion location detection device 1 moves from L1 to L4 while submerged or submerged in the sewage 3 (see FIG. 5a), the liquid level detection sensor 17 does not detect the liquid level.

However, when the corrosion location detector 1 passes through L5, the sewage 33 is flowing in a non-full state, so there is a free water surface 35, and an air pocket 39 is generated above. Therefore, the corrosion location detection device 1 moves in a state where it floats on the free water surface 35 of the sewage water 33 or in a state where a part of it protrudes from the free water surface 35 of the sewage water 33 (see FIG. 5b), and is located above the free water surface 35. Alternatively, this air pocket 39 is detected by the liquid level sensor 17 located at the free water surface 35.

Furthermore, when the corrosion location detection device 1 reaches L6, the sewage water 33 is flowing again in a full pipe state, so there is no free water surface and no air pockets are generated. Therefore, since the corrosion location detection device 1 passes through L6 while submerged or submerged in the sewage 33, the liquid level detection sensor 17 does not detect the liquid level.

Once the corrosion detection device 1 that has moved inside the sewage pipe 31 is recovered on the downstream side of the sewage pipe 31, the rear cover 15 is removed from the case body 11, the measurement push button switch 9 is turned off, and the case is removed. The front cover 13 is removed from the main body 11, the storage medium 25 is taken out from the holder 23, and the stored contents of the storage medium 25 are copied to a personal computer.

FIG. 6 shows an example of displaying survey results stored in a personal computer on a display.

In this example, the free water surface 35 of the sewage water 33 is detected, and the locations where the air pockets 39 are thought to be generated are highlighted (displayed with thick lines). Here, the free water surface 35 of the sewage water 33, and therefore the location where the air pocket 39 is detected, can be estimated to be the location where corrosion occurs.

Next, the configuration of another corrosion location detection device will be described with reference to FIGS. 10 to 13.

Another corrosion location detection device 41 (underwater and waterborne moving objects) is equipped with four liquid level detection sensors arranged at equal intervals in the circumferential direction (of the type shown in FIG. 3a), and further equipped with a photographing camera.

The corrosion location detection device 41 includes a resin case 43, a liquid level detection sensor 45 sealed in the case 43, a moving position detection sensor 47 sealed in the case 43, and a case 43. A video camera 49 is sealed at the tip of the case 43, a plurality of LED lights 53 are provided at the tip of the case 43 so as to surround the video camera 49 (see FIG. 12), A battery 55 is housed in a sealed state and supplies power to the liquid level detection sensor 45, video camera 49, and LED light 53; a control unit 57 is sealed in the case 43; A measurement manual switch 59 is provided to turn on and off the supply of power from the battery 55 to the liquid level detection sensor 45 and the like.

The case 43 includes a cylindrical case body 61, a truncated half-spheroidal front cover 63 removably attached to the front end of the case body 61 via, for example, a gasket, and a rear end of the case body 61. The front cover 63 has a transparent camera plate 67 made of acrylic or the like fixed to the opening at the tip of the front cover 63, and a camera transparent plate 67 made of acrylic or the like is fixed to the opening at the tip of the front cover 63. The camera 49 photographs the inside of the sewer pipe through this camera transparent plate 67. The front cover 63 also has a plurality of light holes 69 formed around the camera transparent plate 67, and a transparent light member 71 made of acrylic or the like is inserted and fixed into each light hole 69. LED lights 53 are arranged on the rear side of each of the transparent members 71 for lights (see FIG. 11). A bolt 73 for operating the manual measurement switch 59 is screwed into the rear cover 65. One end of a hinge lever 75 is in contact with the tip of the operating bolt 73, and by rotating the operating bolt 73 and moving it inward, one end of the hinge lever 75 is pushed and the other end moves. The contact portion 77 is turned on (see FIG. 12). Also, by rotating the operating bolt 73 in the opposite direction and moving it outward, the pressure on one end of the hinge lever 75 is relieved, and the other end moves back, turning the contact portion 77 OFF. (See imaginary line in FIG. 12).

Four liquid level detection sensors 45 are provided at equal intervals in the circumferential direction so as to surround the battery 55, and can include a liquid level detection capacitor 29 similar to the liquid level detection sensor 17. In each liquid level detection sensor 45, for example, a pair of liquid level detection capacitors 29 are arranged so as to open outward. For example, each liquid level detection sensor 45 detects a liquid level when a liquid level is generated radially outward from the position where the liquid level detection sensor 45 is disposed.

When the contact part 77 is turned on by rotating the operating bolt 73 and screwing it inward, the LED light 53 lights up, the video camera 49 starts shooting, and the liquid level detection sensor 45 and movement position detection sensor 47 are activated. do. The control unit 57 associates the video information from the video camera 49 with the position information from the moving position detection sensor 47 and stores it in a removable storage medium 79 such as a memory card, and also stores the detection information from the liquid level detection sensor 45. It is stored in the storage medium 79 in association with the position information from the moving position detection sensor 47. Note that the control unit 57 can be configured so that the video camera 49 starts shooting when the liquid level detection sensor 45 detects the liquid level, and can also be configured so that the video camera 49 starts capturing images while the liquid level detection sensor 45 detects the liquid level. It can be configured such that the video camera 49 only takes pictures. The video information from the video camera 49 can be stored separately from the position information from the moving position detection sensor 47.

As shown in FIG. 13, a balance weight 81 is provided below the control unit 57 in the case body 61, and the corrosion location detection device 41 detects a specific liquid even if it rotates in the circumferential direction. It is configured to automatically return to rotation until the surface detection sensor 45 (the upper liquid level detection sensor 45 in FIG. 10) returns to the upper side. Further, the rear cover 65 is provided with a nitrogen gas filling port (nitrogen gas filling port member) 83 equipped with a check valve (not shown), and nitrogen gas is injected into the case 43 and trapped therein. The pressure inside the case 43 can be made higher than the pressure inside the sewage pipe, thereby increasing the pressure resistance of the case 43 and preventing dew condensation on the video camera 49 and the camera transparent plate 67.

Further, the operation of the video camera 49 and the reception of captured images from the video camera 49 can be performed using a wireless communication terminal separate from the liquid level detection capacitor 29 or the liquid level detection sensor 45.

1, 41 Corrosion point detection device 3, 43 Case 17, 45 Liquid level detection sensor 31 Sewage pipe 33 Sewage 35 Free water surface 37 Pumping station

Claims (1)

A corrosion location detection device for estimating interior corrosion locations of a sewage pipe in which a pumping station having a pump is installed,
During the operation of the pump, sewage is poured into the sewage pipe, and the sewage in the sewage pipe is flowing along with the flow of the sewage in a full pipe state, and the range in which the sewage is flowing in a non-full pipe state. Underwater and water-based moving objects that move downstream in the range where they are located;
A liquid level detection sensor for detecting the presence or absence of a free water surface of sewage, which is provided on the underwater and waterborne moving body,
The underwater and surface moving bodies are configured to move while floating on the free water surface in a range where sewage is flowing in a non-full state,
The underwater and above-water moving object further has a photographing camera at the tip thereof,
The photographing camera is a video camera,
Corrosion point detection characterized in that the video camera starts taking pictures when the liquid level detection sensor detects a free water surface, or takes pictures only while the liquid level detection sensor detects a free water surface. Device .

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