JPH07103960B2 - Pipeline leak detection method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a pipeline network and
The present invention relates to a pipeline network leakage detection method for detecting leakage of fluid flowing through a piping network. In addition, this leak detection method is applicable to all flows in piping systems, including single-phase liquid and gas flows, gas-liquid two-phase flows, solid-liquid two-phase flows, solid-gas three-phase flows, and non-Newtonian flows. It is possible.

[0002]

2. Description of the Related Art Conventionally, this type of pipeline leakage detection method has been adopted in the flow rate-pressure boundary condition regardless of whether the numerical solution method of characteristic four-line method, explicit solution method or implicit solution method is used in the technology of pipeline flow simulation. Based on this, the flow state was simulated and leakage was detected by comparing the calculated pressure / flow rate with the measured pressure / flow rate.

[0003]

In the above-mentioned conventional pipeline leak detection method, the flowmeter installation interval is long, so the simulation section is long, and it is difficult to improve the accuracy of the simulation, so the leak detection performance is poor. In addition, there is a drawback that only the leak can be judged in the flow meter installation section and the accuracy of the leak position detection cannot be improved. In view of the above-mentioned drawbacks, the present invention uses not only data of a station in which a flow meter is installed but also pressure data of many valve stations installed in an intermediate portion of a pipeline to divide a pipe into short distances between valve stations. An object of the present invention is to provide a pipeline leak detection method having high leak detection performance by simulating the flow state of a line by a characteristic curve method or the like. To be precise, rather than a valve station, it simulates the flow state of a pipeline section between pressure measurement points and detects leaks. For the flow analysis by the characteristic curve method described above, refer to “Fluid Transient,” EBWyl as a reference.
ie.al, FEBPrest.1983, etc. That is, the flow state in the pipeline is expressed as a continuous equation, a motion equation, and a partial differential equation of an energy equation. It is a numerical solution that determines the flow state.

[0004]

SUMMARY OF THE INVENTION A pipeline leak detection method of the present invention comprises a pressure gauge and a thermometer which are respectively installed at respective valve stations of a pipeline.
Temperature data is collected, the flow rate passing through the flow state in each section is calculated from the pressure and temperature data as one section between each valve station, and the virtual leak flow rate of each valve station is calculated from the adjacent upstream section. Obtained from the difference between the flow rate flowing into the valve station and the flow rate flowing out from the valve station to the adjacent downstream section, the virtual leak flow rate is averaged at a predetermined constant time interval, and the virtual leak average flow rate is predetermined. At the time interval, when a leak is detected when the threshold is exceeded, and when a leak is detected, the valves before and after the leak occurrence section between the valve stations where the virtual leak flow rate exceeds the threshold The leak position is detected from the virtual average leak rate of the station, or multiple valves are installed in the pipeline. Pressure data and temperature data of the fluid flowing through the pipeline from the pressure gauge and thermometer of the station, respectively. From the pressure and temperature data, each valve station is defined as one section, and the flow state in multiple sections and each section are maintained. Calculate the amount of line pack that is the mass of the fluid being, calculate the mass imbalance of each section from the difference between the inflow mass and the outflow mass of each section and the amount of line pack before and after the time interval at constant time intervals, It is detected that there is a leak in the section when the mass imbalance exceeds a predetermined threshold value, and when the leak is detected, the mass imbalances of the sections adjacent to the front and rear of the leak occurrence section are detected. The leak position is detected from the ratio of the magnitudes of.

The inflow rate used for the virtual leak rate calculation of the valve station at the pipeline inlet and the mass imbalance calculation of the pipeline input section cannot be simulated because the flow cannot be performed because there is no adjacent upstream section. It uses the measured flow rate data from the flowmeter. Similarly, the inflow rate used for the virtual leak rate calculation of the valve station at the pipeline outlet and the mass imbalance calculation of the pipeline outlet section uses the measured flow rate data from the flowmeter.

[0006]

[Operation] From the pressure / temperature data of each valve station, one valve section is defined as one section, and the flow state in each section is calculated. As a difference between the inflow and outflow rates from the adjacent upstream and downstream sections to each valve station. The virtual leak flow rate of each valve station is calculated, averaged at fixed time intervals, and when the virtual leak average flow rate exceeds a certain level, it is determined that there is a leak, and the virtual leak average of the valve stations upstream and downstream of the section where the leak has occurred. The leak position is detected from the flow rate. Furthermore, from the same pressure and temperature data, the mass imbalance of each section is calculated from the difference between the inflow and outflow mass of each section and the line pack amount. The leak position is detected from the ratio of the magnitudes of the mass imbalances in the upstream and downstream sections of the section where

[0007]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a diagram showing a pipeline to which the first and second embodiments of the pipeline leak detection method of the present invention are applied. For simplicity, the flow meter and thermometer figures are omitted. Conventional flowmeters installation interval similar long distance between the valve stations ESV1, ESV2, ~, ESVn respectively distances L _1, L _2, ~, are arranged in the pipeline at a L _n-1. Valve station ESV1, ESV
2, ..., The pressure of the fluid passing through ESVn is measured by pressure gauges PM1, PM2 ,.
A / D conversion is performed by the D converters CV1, CV2, to CVn, and the data is transmitted to a central processing unit (not shown) via the transmission line TRN together with other temperature data and the like. The transmission line TRN uses a telephone line or radio. The pipeline is a gas line with a diameter of 18 inches and a length of 254 km.
The flow rate at 100% load was 3.25 × 10 ⁶ m ³ / day (standard).

Next, the first embodiment will be described with reference to FIGS. 2 (a) and 2 (b).
, (C), the method of leak detection and leak position detection will be described. In addition, in order to simplify the explanation,
We chose an example of a steady moving state.

The distance L _BC among the plurality of valve stations
A leakage of a constant flow rate G occurs at a distance X from the valve station B between the valve stations B and C which are provided at intervals. A constant flow rate G ₀ flows from the valve station C to the valve station D (FIG. 2 (a).
, (B)). Each valve station A, B, C, respectively a virtual leak rate at _{D G A, G B, G} C, when the G _D, virtual leak rate is the inlet flow to the valve station and out of the valve stationery Because of the difference in flow rate, G _A = 0 and G _D = 0, and valve station A
And the virtual leak rate of valve station D is zero. On the other hand, since the leakage flow rate G is generated between the valve station B and the valve station C, the flow rate between the valve stations B and C calculated from the pressure-pressure boundary condition is G _O + G or G _O. without expressed this intermediate When G'at a flow rate using a virtual leak rate G _B of the valve stations _{B G'= G O + G-} G B.
Therefore, Eqs. (1) and (2) and Eq. (3) from both formulas are required.

P _B ² −P ² = C * (G _O + G) ² X (1) P ² −P _C ² = C * G _O ² * (L _BC −X) (2) P _B ² − P _C ² = C * (G _O + G−G _B ) L _BC (3) where C: constant value related to inner surface roughness, inner diameter, etc. G: leakage flow rate (= G _B + G _C ) P _B : at valve station B Pressure P _C : Pressure at valve station C P: Pressure at leak point L _BC : Pipeline length between valve station B and valve station C In other words, the change due to leak appears only in the leak occurrence section as a virtual leak flow rate. . And G _B = G _O + G
Since −G ′, G _C = G′−G _O, G _B + G _C = G, and the sum of the virtual leak flow rates of the valve stations B and C becomes the leak flow rate G. Even in a transient state where there is a load fluctuation, the flow simulation will
The flow rate, pressure and temperature fluctuations are accurately evaluated and can be corrected. Further, from the equations (1), (2), (3), the pressure sources P, F
_G, erases the P _C, equation (4) is determined, the leakage point is also know exactly using a virtual leak rate G _B G _C.

[0012]

[Equation 1] In other words, as shown in the pressure profile of FIG. 2 (C), if there is no leakage, there will be a linear gradient such as A ', B', C ', D', but if leakage has occurred, A ", B"
Since the slope of C and the slope of C "and D" are not linear, the above principle of leak detection is established.

Next, a second embodiment applied to the pipeline of FIG. 1 will be described.

Each of the valve stations ESV1, ESV2, ..., By the pressure temperature data sampled from the pressure gauges PM1, PM2 ,.
The inflow mass, the outflow mass, and the line pack amount of each section passing through ESVn are calculated, and the mass imbalance of each section is obtained by the equation (5). Cumulative outflow mass in cumulative inflow mass -t ₁ ~t ₂ h in the mass imbalance = t ₁ ~t ₂ hour - changes in pipeline gas mass

[0015]

[Equation 2] However, Gin (t) ... Inflow mass Gout (t) ... Outflow mass ρ (t) ... Density A ... Pipe cross-sectional area X ... Distance t ... Time Mass balance is a threshold value preset in consideration of simulation error and measurement error. If it exceeds, it is assumed that leakage has occurred.

It will also be apparent that the leak occurrence position is obtained from the ratio of the mass imbalance magnitudes of the sections before and after the leak.

In this embodiment, in parallel with observing the mass imbalance of each section, the mass imbalances of the sections are summed up to observe the mass imbalances of a part of the pipeline and the entire pipeline. It is also possible to cancel the plus or minus error that has occurred when calculating the mass of the section and perform leak detection with higher accuracy.

[0018]

As described above, according to the present invention, by using the pressure / temperature data of the bubble stations arranged in the long distance pipeline, the leakage can be detected within a short distance between the valve stations, and the leakage can be realized. There is an effect that the point can be accurately detected.

[Brief description of drawings]

FIG. 1 is a diagram showing a pipeline to which the first and second embodiments of the pipeline leakage detection method of the present invention are applied.

FIG. 2 is an explanatory diagram showing a first embodiment.

[Explanation of symbols]

 ESV1 to ESVn Valve station PM1 to PMn Pressure gauge CV1 to CVn A / D converter TRN Transmission line

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-49-45419 (JP, A) JP-A-2-162223 (JP, A)

Claims (3)

[Claims] 1. A flow simulation program in which pressure and temperature data are collected from pressure gauges and thermometers of a plurality of valve stations arranged in a pipeline, and a section between the valve stations is defined as one section from the pressure and temperature data. The flow state related to the flow, pressure, and temperature in each section is calculated, and the virtual leakage flow rate of each valve station is calculated from the flow rate flowing into the valve station from the adjacent upstream section and the valve station to the adjacent downstream section. It is calculated from the difference with the flow rate flowing out from the virtual leak rate, and the virtual leak flow rate is averaged at a predetermined constant time interval, and there is a leak when the virtual leak average flow rate exceeds a threshold value at the predetermined time interval. That the average leakage flow rate exceeds the threshold value Pipeline leak detection method that detects the leak position from the virtual leak average flow rate of the valve station before and after the valve. 2. Pressure and temperature data are respectively collected from pressure gauges and thermometers of a plurality of valve stations arranged in the pipeline, and characteristic curves and the like are formed from the pressure and temperature data as a section between the valve stations. Using the flow simulation program of, calculate the flow state related to the flow, pressure, and temperature in each section and the line pack amount, which is the mass of the fluid held in each section, and keep the inflow mass and outflow mass of each section constant. The mass imbalance of each section is calculated at fixed time intervals from the difference in the amount of line packs before and after the time interval, and when the mass imbalance exceeds a predetermined threshold, it is detected that there is a leak in the section. However, the leakage position is detected from the ratio of the mass imbalance magnitudes of the adjacent sections before and after the leakage occurrence section. Pipeline leak detection method to be issued. 3. When observing the mass imbalance of each section when detecting the leak position from the ratio of the magnitudes of the mass imbalances of the adjacent sections,
Mass imbalance of each section is added together to observe the mass imbalance of a part of the pipeline and the entire pipeline, and the positive or negative error that occurs when calculating the mass of each section is canceled to detect leaks with higher accuracy. The pipeline leakage detection method according to claim 2, wherein