CZ2021347A3 - System for monitoring the leak of wastewater from a double-skin sewer in real time - Google Patents

Abstract

The system for real-time monitoring of the leakage of wastewater from a double-walled sewer, using temperature measurement with an optical cable based on the principle of Raman light scattering, contains three optical cables (1, 2, 3) running parallel to the sewer pipes. The lower cable (1) to detect the leakage of waste water from the outer shell (5a) of the sewage pipe (5) into the subsoil (6) is freely routed at a level of 20 to 100 mm below the lowest point of the outer shell (5a) of the double-shell sewer, the upper cable ( 2) to detect damage to the double-skinned sewer pipe (5) due to human factors, especially during excavation work, it is routed at a level of 50 to 200 mm above the highest point of the outer shell (5a) in the micro-protector and the central cable (3) for continuous monitoring of wastewater leakage from of the inner pipe (5b) into the interspace of the double-skinned sewage pipe (5) is led in the interspace of the double-skinned sewage drain at the bottom of the outer shell (5a) of the pipe in grommets connected to spacer sleeves (5c) ensuring the spacing between the inner pipe (5b) and the outer shell (5a ) double-walled sewers. One or both ends of all three cables (1, 2, 3) are brought out to the evaluation unit to evaluate the signals of the monitoring optical cables (1, 2, 3) at specified time intervals.

Description

A system for monitoring the leakage of wastewater from a double-wall sewer in real time

Field of technology

The invention relates to a system for monitoring the leakage of waste water from a double-wall sewer in real time, using temperature measurement with an optical cable based on the principle of Raman scattering of light.

Current state of the art

The double-layer sewer is used in environmentally exposed areas where a potential pipe failure and leakage of waste water into the subsoil could lead to significant environmental damage. In the case of highly environmentally exposed areas, i.e. for example in areas where groundwater sources for the collection of drinking water may be degraded, additional levels of sewage network security may be required by the relevant authorities.

One of the options for such security is the implementation of continuous remote monitoring of the technical condition with an online warning system for reporting malfunctions. However, this security has not yet been comprehensively solved by specializing in double-walled sewers. Only partial solutions related to this issue are known.

For example, the subject of Chinese utility model CN 209782254 U is a pressure drain (drainage) pipe with water leakage detection. The pressure pipe is placed in the second drainage pipe, on which measuring cells are placed at certain intervals. When pressurized water leaks from the internal pipe into the drainage pipe, the drainage pipe is filled to pressure mode. During the pressurization of the drainage pipe, leaked water enters the measuring cell, which is located along the route of the drainage pipe, where the presence of water - a leak - is detected using a contact sensor, and which is subsequently signaled. The disadvantage of this water leak detection solution is that it is implemented in measuring cells, not continuously along the entire length of the pipeline. This results in the necessity of accurate localization of the leak site by additional searching for it in the area of the relevant measuring cell, as well as increased investment and operating costs for measuring equipment - each measuring cell must be equipped with a contact sensor.

The solution of the water leak detection system from the pressure water pipeline according to the Korean patent application KR 20180102847 A, based on the temperature measurement with an optical cable (on the principle of Raman light scattering), contributes to the elimination of the above-mentioned shortcomings. The optical cable is routed next to the pipe in the protective cable, the contact of the optical cable with the leaked water is ensured by means of holes in the protective cable equipped with a filter layer. However, the mentioned system with one optical detection cable cannot be used for double-layer sewers, both from a principle point of view and because of the different construction of the cable fastening. The protector fastening system in patent application KR 20180102847 A, for example, cannot be applied for fixing the cable in the interspace of a double-wall sewer.

Within the framework of the known state of the art, a relatively large number of inventions deal with the issue of routing various types of cables inside sewer pipes. These are mainly procedures for the additional installation of cables into existing single-wall sewer pipes. This involves the installation of a completely separate channel from the sewerage area itself, using a pipe insert with added channels on the outside of the insert - see, for example, European patent EP 1271728 Bl, Czech patent CZ 292760 B6, or a partially separated channel of a cable protector, which they are fixed with special fasteners (Czech published patent application PV 2019-369 i.e. CZ 2019369 A3) or built-ins (published US patent application US 20110309314 AI). However, these solutions only focus on running the optical cable in the sewer. Its reason is the reduction of investment costs for networking a new area, when it is not necessary to dig a separate trench, or management coordination

- 1 CZ 2021 - 347 A3 of an optical cable with protective bands of other networks, not for the detection of water leakage from the sewage system. This also results in the autonomy of the cable on the flowing medium, when there is no contact between the cable and the waste water. In order to use the optical cable as a monitoring element, however, the best possible interaction with the wastewater is necessary. In addition, the installation of the optical cable using the above-mentioned procedures does not allow its placement in the interspace of the double-walled sewer.

The essence of the invention

To eliminate the shortcomings of known solutions, the system for monitoring the leakage of waste water from a double-wall sewer in real time according to the invention, which uses temperature measurement with an optical cable based on the principle of Raman scattering of light, contributes to a large extent. The essence of the invention lies in the fact that this system contains three optical cables running parallel to the sewer pipes. The lower cable to detect the leakage of waste water from the outer jacket of the sewer pipe into the subsoil is freely routed at a level of 20 to 100 mm below the lowest point of the outer jacket of the double-jacket sewer. The upper cable to detect damage to the double-skinned sewer pipe due to the human factor, especially during excavation work, is routed at a level of 50 to 200 mm above the highest point of the outer shell in the micro-protector. The central cable for the continuous monitoring of the leakage of waste water from the inner pipe into the interspace of the double-skinned sewer pipe is then led in the interspace of the double-skinned sewer at the bottom of the outer shell of the pipe in grommets connected to spacer sleeves ensuring the spacing between the inner pipe and the outer shell of the double-skinned sewer. One or both ends of all three cables are brought out to the evaluation unit to evaluate the signals of the monitoring optical cables at specified time intervals.

The lower and upper cables are routed along the outer shell of the sewer pipe and in the area of sewer manholes then closely around the body of the manhole.

The main benefit of the solution according to the invention lies in the fact that it comprehensively solves the monitoring of the leakage of waste water from the double-wall sewer in non-pressure mode - i.e. detection of water leakage from the inner pipe to the outer protective shell of the pipe, detection of water leakage from the outer shell of the pipe to the surroundings as well as detection of disruption of the integrity of the upper part of the outer shell of the pipe due to mechanical damage. On the other hand, the only known solution using, similar to the solution according to the invention, temperature measurement with an optical cable (based on the principle of Raman light scattering) is exclusively intended only for the detection of water leakage from a single-pipe line in the pressure mode for drinking water supply, in addition to the fact that the contact of the optical cable with the leaked water is secured by holes in the protective cable. Its use to detect the leakage of waste water from a double-wall sewer in non-pressurized mode (with a free level) is therefore not at all possible from a technical point of view - for example, because the protector fastening system according to this known solution cannot be applied to fix the cable in the interspace of the double-wall sewer . On the other hand, the system according to the invention solves this problem by uniquely fitting into the grommets of micro-tubes fixed on spacer sleeves used to define the space between the inner and outer pipes of the double-walled sewer.

Another known method of water leak detection is disadvantageous in comparison to the solution according to the invention in that the water leak detection is implemented in measuring cells, not continuously with an optical cable along the entire length of the pipeline. This results in the necessity of accurate localization of the leak site by additional searching for it in the area of the relevant measuring cell, as well as increased investment and operating costs for measuring equipment - each measuring cell must be equipped with a contact sensor.

Clarification of drawings

The attached drawings serve to clarify the essence of the invention in more detail, where it represents:

-2CZ 2021 - 347 A3 Fig. 1 - cross-section along the axis of a double-layer sewer pipe;

Fig. 2 - longitudinal section of the pipe axis of the double-layer sewer;

Fig. 3 - the situation of cable routing along the pipeline of the double-layer sewerage system; and Fig. 4 - diagram of the evaluation unit.

An example of the implementation of the invention

The system for monitoring the leakage of wastewater from a double-walled sewer in real time, using temperature measurement with an optical cable based on the principle of Raman light scattering (see Fig. 1 to 3) in an exemplary embodiment, includes three optical cables 1, 2, 3 run parallel to the sewer pipes. The lower cable 1 for detecting the leakage of waste water from the outer shell 5a of the sewage pipe 5 into the subsoil 6 is freely routed at a level of approx. 50 mm below the lowest point of the outer shell 5a of the double-skinned sewer. The upper cable 2 to detect damage to the double-sheathed sewer pipe 5 due to the action of the human factor, especially during excavation work, is routed at a level of approx. 100 mm above the highest point of the outer casing 5a in the micro-protector. The middle cable 3 for the continuous monitoring of the leakage of waste water from the inner pipe 5b into the interspace of the double-skinned sewer pipe 5 is led in the interspace of the double-skinned sewage drain at the bottom of the outer shell 5a of the pipe in the grommets connected to the spacer sleeves 5c ensuring the spacing between the inner pipe 5b and the outer shell 5a of the double-skinned sewage drains. One or both ends of all three cables 1, 2, 3 are led to the evaluation unit 4 for evaluation of the signals of the monitoring optical cables 1, 2, 3 at specified time intervals.

The evaluation unit 4 (see diagram in Fig. 4) contains a control unit 8, which consists of a laser source 9, a filter 10 for dividing the transmitted pulse and the received signal, a filter 11 for dividing the Stokes and anti-Stokes components, sensitive photodetectors 12a, 12b for each the component separately and the main control unit 13. The evaluation unit 4_may, in addition to_the control unit 8, also contain an optical switch 14, which enables the connection of multiple routes using outputs 15a to 15n (while ⁿ is in the range of 2n).

The lower cable 1 and the upper cable 2 are guided along the outer shell 5a of the sewer pipe 5 and in the area of the sewer shafts 7 then closely around the body of the shaft.

The procedure for installing a system for monitoring the leakage of wastewater based on optical cables during the construction of a double-walled sewer is as follows:

After excavating the groove of the sewer route and placing the sand bed 6, the lower cable 1 is loosely laid in the sand bed 6 at the place of the expected bottom of the double-skinned sewer, i.e. the lowest point line of the outer jacket 5a of the pipe. Subsequently, the outer shell 5a is laid and its complete backfilling is carried out. In the place above the ceiling of the external pipe, again in the sand cover of the pipe, the upper cable 2 is laid loosely in a narrow-profile flexible protector. Lower cable 1 and upper cable 2 are routed in straight sections in the direction of the pipeline axis. In the locations of inspection shafts 7, the cables are routed closely around their bodies. The middle cable 3 is then installed together with the inner pipe 5b. Part of the section, or even the entire section, of the inner pipe 5b is assembled outside the ground groove and is equipped with sliding spacer sleeves 5c. These spacer sleeves 5c define the position of the inner pipe 5b within the double-wall sewer. The middle cable 3 is then pulled through a microtube, which is fixed to the sliding spacer sleeve 5c so that its position is approximately 2 cm from the outer part of the sleeve and at the same time from the bottom of the outer casing 5a of the pipe. This position of the central cable 3 results in a sufficient response to the resulting malfunction of the inner pipe 5b, and at the same time this solution prevents mechanical damage from the sliding spacer sleeve 5c. This system is then pulled into the outer jacket 5a of the double-jacketed sewer pipe so that the central cable 3 is located at the bottom of the outer jacket 5a of the pipe. Subsequently, there is one ending, or both

-3 CZ 2021 - 347 A3 ends of all optical cables 1, 2, 3 brought out to the evaluation unit 4 located in the control room of the operator of the sewage system.

Cables 1, 2, 3 can also be connected in series, whereby at least one end of the common cable must be brought to the evaluation unit 4.

Industrial applicability The system according to the invention is intended for comprehensive real-time monitoring of the leakage of wastewater from a double-walled sewer, with the fact that this monitoring includes the detection of the leakage of wastewater from the outer casing 5a of the sewer pipe 5 into the subsoil 6, the detection of the leakage of wastewater from the inner pipe 5b into the interspace of the double-walled sewer pipe 5 as well as the detection of damage to the double-walled sewer pipe 5 due to the human factor, especially during excavation work.

Claims (3)

PATENT CLAIMS 1. A system for monitoring the leakage of wastewater from a double-walled sewer in real time, using temperature measurement with an optical cable based on the principle of Raman light scattering, characterized by the fact that it contains three optical cables (1, 2, 3) with the fact that the lower cable (1) to detect the leakage of waste water from the outer shell (5a) of the sewer pipe (5) into the subsoil (6) is freely guided at a level of 20 to 100 mm below the lowest point of the outer shell (5a) of the double-shell sewage drains, the upper cable (2) to detect damage to the double-sheathed sewer pipe (5) due to the action of the human factor, especially during excavation work, is led at a level of 50 to 200 mm above the highest point of the outer casing (5a) in the micro-protector and the middle cable (3) to for the continuous monitoring of the leakage of waste water from the inner pipe (5b) into the interspace of the double-skinned sewer pipe (5) is led in the interspace of the double-skinned sewage drain at the bottom of the outer shell (5a) of the pipe in grommets connected to spacer sleeves (5c) ensuring the spacing between the inner pipe (5b ) and the outer jacket (5a) of the double-jacketed sewer and further that one or both ends of all three cables (1, 2, 3) are led to the evaluation unit (4) for evaluation of monitoring signals of optical cables (1, 2, 3) at specified time intervals. 2. A system for monitoring the leakage of waste water according to claim 1, characterized in that the cables (1, 2, 3) are connected to each other in series, while at least one end of the resulting common cable is fed into the evaluation unit (4). 3. A system for monitoring the leakage of wastewater according to claim 1, characterized in that the lower cable (1) and the upper cable (2) are routed along the outer jacket (5a) of the sewer pipe (5) and in the area of the sewer manholes (7) just around the body of the shaft.