JPH02147930A - Leakage detection for pipeline - Google Patents

Abstract

PURPOSE:To detect a small leakage accurately by a method wherein a pressure gradient is determined between specified measuring positions using a measured pressure value obtained with a manometer and a leakage is determined to occur in a pipeline when a value of the pressure gradient is deviated from a predetermined range. CONSTITUTION:Pressure values measured with a plurality of manometers 21-26 set on a gas pipeline 1 are inputted into an input circuit 3 to be transmitted to an A/D converter 4 and the measured pressure value transmitted from the input circuit 3 is converted into a digital signal to be transmitted to an arithmetic circuit 5 of a computer 8. With the arithmetic circuit 5, based on the measured pressure value, a pressure gradient is calculated to be transmitted to a judging circuit 6, which 6 judges the presence of a leak caused based on the pressure gradient. As a result, when the presence of the leak is determined with the judging circuit 6, a leakage signal is outputted from an output device 7 as external indication signal and a display is performed by a symbol, a lamp or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for detecting leakage of fluid from a pipeline, particularly during transportation, in a pipeline that transports a fluid such as oil gas or natural gas. It is.

(Prior Art) In general, gas leaks in gas pipelines not only result in losses, regardless of the amount of leakage, but may also lead to dangerous situations such as explosions. For this reason, conventional methods for detecting leaks in gas pipelines include having workers patrol along the pipeline with gas detectors, or installing pressure gauges along the pipeline to monitor and check the pressure. A method has been implemented in which it is determined that a leak has occurred when the measured value of is less than a predetermined lower limit value.

(Problem to be solved by the invention) However, the method in which workers patrol along the pipeline with gas detectors requires a great deal of labor and is inefficient, as well as the method of patrolling the entire pipeline. Since constant monitoring is not possible, leaks may be detected too late.

Furthermore, in a method in which a pressure gauge is installed in a pipeline to monitor the pipeline and a leak is determined to have occurred when the measured pressure value falls below a predetermined lower limit value, the leak that can be detected is limited to extremely large amounts.

The present invention was made to solve the above-mentioned problems, and its purpose is to continuously and automatically monitor the entire pipeline so that small leaks can be reliably detected. The purpose of this invention is to provide a pipeline leakage detection method.

(Means for Solving the Problems) In order to achieve the above object, the pipeline leakage detection method according to the present invention includes installing a plurality of pressure gauges at predetermined intervals in a pipeline that transports fluid. , the pressure gradient between predetermined measurement positions is determined using the pressure measurement values from these pressure gauges, and if the value of this pressure gradient deviates from a predetermined range, it is determined that a leak has occurred in the pipeline. I have to.

(Function) When a leak occurs in a pipeline, the pressure drop pattern along the length of the pipeline changes.

As a result, the pressure difference between adjacent pressure measurement positions, that is, the pressure gradient, changes significantly when a leak occurs. Therefore, it is possible to monitor the pressure gradient between predetermined measurement positions and determine that a leak has occurred in the pipeline if the pressure gradient deviates from a predetermined range.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a conceptual diagram showing an example of a pipeline equipped with a pressure gauge according to the present invention. In FIG. 1, 1 is a gas pipeline installed to transport gas such as oil gas or natural gas, and 21 to 26 are multiple pipelines installed at predetermined intervals on this gas pipeline 1. Of the plurality of pressure gauges 21 to 26, the 21 side is on the upstream side of the gas pipeline 1.

FIG. 2 is a diagram showing an example of a pressure distribution curve of the gas pipeline 1 without leakage. In FIG. 2, the horizontal axis is the length of the gas pipeline 1, and 81 to S6 are the plurality of pressure gauges 2.
At each measurement position 1 to 26, the vertical axis is the internal pressure of the gas pipeline 1, and A is a pressure distribution curve based on each pressure measurement value measured by a plurality of pressure gauges 21 to 26. From this pressure distribution curve A, it can be seen that the pressure in the case where there is no leakage in the gas pipeline 1 decreases as it goes downstream from the -1- flow, and draws a parabola that curves toward the high pressure side.

FIG. 3 is a diagram showing an example of a pressure distribution curve of the gas pipeline 1 when a leak occurs at the measurement position of S4 and an example of a pressure distribution curve of the gas pipeline 1 when there is no leak.

From this figure 3, it is understood that the pressure decreases the most at the measurement position S4 where the leak occurs, and from this leak position S4, the pressure gradient becomes larger on the second flow side and becomes smaller on the downstream side. can.

- Figure 4 is an explanatory diagram for expressing the pressure gradient of the gas pipeline 1 using a mathematical formula. In FIG. 4, 51-
1 to S1+1 are between certain measurement positions in the gas pipeline 1, Sl is the leakage position, S1-1 is upstream of the leakage position S1, S1+1 is downstream of the leakage position S1, Ll-1 is S i-1 and St, Li is the interval between St and s l+1, and P i-1-P l+1 is the above 51-1 to s
Each pressure measurement value when there is no leakage and when there is a leakage between the measurement positions of ill, A is the pressure distribution curve of the pressure measurement value when there is no leakage, and B is the pressure distribution curve when there is a leakage. A pressure distribution curve of pressure measurement values is shown.

The pressure gradient in the section between Ll-1 and Ll of the pressure distribution curves A and B can be calculated using the following formulas.

G1-1- (PI-1-Pi') /Ll-1...
・(1) Gi = (Pi l − Pill ) /L
i...(2) Here, ci-i: section L1-
G1: Pressure gradient in section Li.

Comparing the pressure distribution curve A of the pressure measurement value when there is no leakage and the pressure distribution curve B of the pressure measurement value + value when there is a leakage based on the above formula (1),
As the pressure gradient G l-1 in the section L I-1 upstream from the leakage position St increases, the pressure gradient G l-1 in the section L I-1 on the downstream side increases.
It can be seen that the pressure gradient G1 becomes smaller.

Therefore, when the pressure gradient between predetermined measurement positions exceeds a predetermined value as shown in the equation below, it can be determined that a leak has occurred.

When upstream from the leakage position: Gl 〉 ε11 When downstream from the leakage position: G1 〉 ε21... (
4) Here, ε11. ε21 is a set value.

FIG. 5 is an explanatory diagram when the leakage position is located in the middle of the measurement position. In FIG. 5, 5i-1 to S1,22 are between predetermined measurement positions in the gas pipeline 1, 51-1 is on the upstream side, S1+2 is on the downstream side, L i-1 is the section between S i-1 and 81, Ll is the interval between Sl and sill, L
ill is the section between Sill and 81+2, the leakage position is in the middle of section L1, and P I-1-P i+2 is the section between Sill and 81+2.
-i -s Each pressure measurement value when there is no leakage and when there is leakage between i+2, A is the pressure distribution curve of the pressure measurement value when there is no leakage, and B is when there is leakage. shows the pressure distribution curve of the pressure measurement values at . According to this Figure 5, even if the leak position is in the middle of the measurement position, the leak can be detected by performing the above process in the same way using the pressure gradient in the sections upstream and downstream of the section where the leak is located. Understand what you can do.

- Figure 6 is a block diagram showing a configuration example of a leak detection device used when implementing the method of the present invention. This leak detection device inputs the pressure measurement values from the pressure gauges 21 to 26 installed at each measurement position in the gas pipeline 1, and calculates the pressure gradient in an arbitrary section (between measurement positions) based on these pressure measurement values. This pressure gradient is monitored and a leak signal is output in the event of a leak.

That is, in FIG. 6, 21 to 26 are a plurality of pressure gauges installed at predetermined intervals in the gas pipeline 1, 3 is an input circuit for inputting the pressure measurement values measured by these pressure gauges 21 to 26, and 4 is an A/D converter that converts the analog signal from this input circuit 3 into a digital signal, 5 is an arithmetic circuit that calculates the pressure gradient based on the output signal from this A/D converter 4, and 6 is this arithmetic circuit. A determination circuit that (comprehensively) determines whether or not a leak has occurred based on the pressure gradient from 5; 7 is an output device that outputs a leak signal when the determination circuit 6 determines that a leak has occurred; 8 is an arithmetic operation circuit 511
This is a computer with a built-in metering path 6.

Next, the operation of the present leak detection device will be explained.

A plurality of pressure gauges 21 installed on the gas pipeline 1
The pressure measurement value measured by 26 is input manually to the input circuit 3, and is transmitted from there to the A/D converter 4. The A/D converter 4 converts the pressure measurement value transmitted from the input circuit 3 into a digital signal, which is then transmitted to the arithmetic circuit 5 of the computer 8 . In the arithmetic circuit 5 of the computer 8,
A pressure gradient is calculated based on the pressure measurement value transmitted from the A/D converter 4, and is then transmitted to the determination circuit 6.

The determination circuit 6 determines (overall) whether or not a leak has occurred based on the pressure gradient transmitted from the arithmetic circuit 5. As a result, if the determination circuit 6 determines that leakage has occurred, the leakage signal is output from the output device 7 as an external display signal, and this external display signal is displayed, for example, as a numerical value, symbol, lamp, etc. on an appropriate display. be done. In addition, in this leak detection device, it is possible to estimate the leak occurrence position by using the above-mentioned equations (3) and (4).

In this embodiment, a plurality of pressure gauges 2 are installed at predetermined intervals on a gas pipeline 1 that transports gas.
The pressure gradient between predetermined measurement positions is determined based on the pressure measurement values measured in steps 1 to 26, and when the value of this pressure gradient deviates from a predetermined range, it is determined that a gas leak has occurred in the gas pipeline 1. Since the leakage of the gas pipeline 1 can be continuously and automatically monitored over the entire gas pipeline 1 and reliably detected, the safety measure-F can obtain an extremely excellent effect. becomes possible.

Although the method of the present invention is particularly effective when applied to gas pipelines, it is clear that it can be similarly applied to liquid pipelines, and in this case, it is more reliable than conventional methods. You can get sex.

(Effects of the Invention) As explained above, according to the present invention, a plurality of pressure gauges are installed at predetermined intervals in a pipeline for transporting fluid, and a predetermined measurement is performed using pressure measurement values from these pressure gauges. The pressure gradient between the M1 positions is determined, and if the value of this pressure gradient deviates from a predetermined range, it is determined that a leak has occurred in the pipeline. A pipeline leak detection method that can automatically monitor and reliably detect small leaks can be provided.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing an example of a pipeline equipped with a pressure gauge according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of a pressure distribution curve of a gas pipeline without leakage, and FIG. Comparison diagram showing an example of each pressure distribution curve of a gas pipeline in a case where a leak occurs and a case where there is no leak,
Fig. 4 is an explanatory diagram for expressing the pressure gradient of a gas pipeline with a mathematical formula, Fig. 5 is an explanatory diagram when the leak position is in the middle of the measurement position, and Fig. 6 is used when implementing the method of the present invention. FIG. 2 is a block diagram showing an example of the configuration of a leakage detection device. 1... Gas pipeline, 21-26... Pressure gauge,
3... Input circuit, 4... A/D converter, 5... Arithmetic circuit, 6... Judgment circuit, 7... Output device, 8...
Computer. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 3 sl s2 53 54S5 55, Figure 2 51.1 Figure 5

Claims (1)

[Claims] Multiple pressure gauges are installed at predetermined intervals on a pipeline that transports fluid, and the pressure values measured by these pressure gauges are used to determine the pressure gradient between predetermined measurement positions, and the value of this pressure gradient is determined in advance. A pipeline leak detection method, characterized in that it is determined that a leak has occurred in a pipeline when the pipeline deviates from a specified range.