JPS58167938A - Leak detector for pipeline - Google Patents

Abstract

PURPOSE:To detect the occurrence of leak in a pipeline without performing mechanical processing on the pipe by a simple means to which a sound sensor capable of detecting supersonic waves being propagated through the wall of the pipeline is additionally provided. CONSTITUTION:The outputs of sound sensors 11, 12 provided at the upper stream and lower stream sides of a pipeline 10 are amplified (a) and converted into digital signals by an A/D converter (b), and (n) pieces each of signal Xi sampled at an interval of very short time are stored in data buffers I , II in sequence. Signal Xi taken out from the data buffers I , II (n) pieces each are added to a leak occurrence detection index calculation circuit (c), and a leak occurrence detection index (LEAK) is calculated. The leak occurrence detection circuit gives (n) pieces of signal Xi to a correlation circuit (d) and calculates a correlation value gammak, and then a coefficient alphak is calculated in a coefficient circuit (e), and based on those calculated values, a variance alphae<2> is calculated by a variance circuit (f), and further the calculation of a leak occurrence detection index is carried out by an index calculation circuit (g).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for detecting the occurrence of fluid leakage in various pipelines.

For example, leaks in oil pipelines not only cause a decrease in productivity, but also cause environmental damage, which poses problems. In this case, in the first step, we have already proposed a detection device that can easily and easily detect the occurrence of fluid leaks in pipelines, and even the smallest leaks online. ing.

However, since this detection device detects fluid pressure and pressure gradient inside the pipeline, it is necessary to drill a hole in the pipe for installing the pressure sensor, and the pressure sensor is always inside the pipeline. If the fluid contains foreign matter, consideration must be given to prevent normal operation from being hindered by the adhesion of such foreign matter.

Further, the present invention provides that the fluid in the pipeline is a gas,
It can be applied not only to liquids or their two-phase flow, but also to cases where they contain solids, and as mentioned above, this method also eliminates the need to drill holes in pipes. Therefore, the present invention provides a versatile leakage detection device that has almost no restrictions on applicable fluids.

The leakage detection device of the present invention includes an acoustic sensor attached to the pipeline to detect ultrasonic waves generated due to fluid leakage, and a leakage detection index LEAK based on the output of the sensor. It is characterized by seeking.

It is assumed that there is a leakage point B between these detector mounting positions (1) and (2). The acoustic sensor (acoustic emissive sensor) detects the ultrasonic waves generated due to leakage of the body and transmitted through the pipe wall,
Therefore, apart from the case where it is necessary to attach it to the inner surface of the tube wall, generally it is sufficient to attach it to the outer surface of the tube wall.

The leak detection device of the present invention basically detects the occurrence of a difference in the statistical properties of the acoustic sensor output, and thereby detects the occurrence of leak.
The above acoustic sensor output is calculated by calculating the leakage detection index LEAK by passing the acoustic sensor outputs upstream and downstream of the actual line through a digital filter, and using this leakage detection index, the statistics of the previously detected data and the current data are calculated. This makes it possible to detect the occurrence of a leak by checking whether the two properties are equal or not.

That is, the upstream and downstream acoustic sensor outputs (X,''), (X7) (i=1, 2,..., n) that fluctuate irregularly
), calculate Xi from this data and calculate (X7) (j=1, 2
.

...＋　”　), Here, ek=N(0, bow) white noise.

When viewed as a whole, including the aftermath, it is an unsteady process, but the time before and after the leakage can be regarded as a steady time series. In this case, the optimal m for 6 data tL' in advance. Assume that the following autoregressive model has been obtained, and then (i) combine the n□ data with the initial n0 data (SO+
Either fit a new model M (m-order autoregressive model) to the n□ data, or (ii) fit another model M1 (m□) to the n□ data.
Either fit the following autoregressive model, ) or use LEAK to determine if (if) then (i)
This shows the basic configuration of the leakage detection device. After being amplified by this leakage detection device, it is converted into a digital signal by an A/D converter, and n signals X are sampled at minute intervals.
j are sequentially stored in data buffers (1) (11). This data buffer (1) (II)
By adding the n signals Xi extracted from the leakage detection index LEA to the leakage detection index calculation circuit,
To calculate K, which leakage detection index calculation circuit first calculates the correlation value γ by adding the above n signals Xi to the correlation circuit, then calculates the coefficient αk in the coefficient circuit, and calculates the variance The circuit calculates the variance σ based on these calculated values, and the index calculation circuit calculates the variance σ based on the above calculation results.7. ．． 1 In this correlation circuit, the correlation value γk is
The output of the delay circuit is delayed up to h times, the output of the delay circuit is sequentially multiplied by the current input signal in the multiplier, each addition is performed in the adder, and the result of the addition is multiplied by - to obtain the correlation value γ. , γ□,...n, and γ are calculated.

The coefficient circuit has a correlation circuit output γ7. Based on the coefficient akt-1 of the digital filter? ' ” 43
k"9&-j11611 (3) (However, j=1,
2, ..., m), and calculates the -degree equation with the variance σl for Hk, the multiplier that multiplies the input of - and the input of 9o"""9m, and their multiplication results. It is possible to configure as many as K adders that add up to obtain 32.

The index calculation circuit calculates n, σ, and
Based on the values of and m, the leakage detection index LEAK is calculated as
5) As shown in the figure, inσJ that has passed through the ln circuit is multiplied by n in a multiplier, and then the multiplier output is multiplied by 2Xm in advance. By performing the addition, the LEAK leakage determination circuit is obtained as described above (LEAK)
i and (LEAK)it correspond to the cases (i) and (it) above, (LEAK)i=(n6+n,)lnQ2+2(??L
+2)(LEAK)it=y+@In a(,+n1
1net,” +2 (?710 +ml+4)・
...(7) If DLEAK〉O, it is normal, DL
If EAK<0, it is assumed that a leak has occurred and is displayed or an alarm is issued.

As is clear from the detailed description above, according to the present invention, it is possible to easily detect the occurrence of leakage in pipelines, and it can also be easily installed on existing pipelines in case of fluid leakage. It is possible to detect the occurrence of a leak.

[Brief explanation of the drawing]

) FIG. 7 is a block configuration diagram of an embodiment of the present invention, and FIGS. 2 to 2 are circuit configuration diagrams of the correlation circuit, dispersion circuit, and index calculation circuit in FIG. 1. 10.e.pipeline, 11, 12...acoustic sensor. 11m1 Figure 2

Claims (1)

[Claims] 1. An acoustic sensor is attached to the pipeline to detect ultrasonic waves that are not generated due to fluid leakage, and this sensor is used to detect leakage based on its output. LEAK = n 1na6 + 2m Where, n: Number of data σ,: Error variance m: A leakage detection index calculation circuit calculated based on the order of the filter is connected, and this calculation circuit calculates the leakage detection index based on the above leakage detection index LEAK. A pipeline leakage detection device, characterized in that a leakage determination circuit is connected to determine whether or not a leakage has occurred.