JPS58100730A - Method and device for detecting leakage of pipeline - Google Patents

Abstract

PURPOSE:To detect leakage securely at its early stage without malfunction by measuring the time difference when the time variation rate of pressure between adjacent pressure detection points exceeds a set value. CONSTITUTION:Pressure signals P0-Pn from detectors H0-Hn at pressure detection point K0-Kn of a pipeline are sent to a time variation rate device 5. Those pressure signals are transduced into a time variation rate signal dP/dt, which is inputted to a comparator 6 to be compared with the set value of a setter 7; when it exceeds the set value, an output signal is sent to an OR circuit 8 and an AND circuit 9. A time limit device 10 operates by the output of the OR circuit 8 and stops by the output of the AND circuit 9. The output of the time limit device 10, i.e. time difference is inputted to a comparator 11, which compares the input with the set time of a time setter 14 determined by pressure detection point distance and a pressure propagation speed; when the time ratio is nearly equal, the comparator 11 sends an output signal to an alarm 12.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for detecting leakage of a transfer fluid in a pipe line used for transferring fluid.

Pipelines are widely used to transport fluids, but especially when transporting flammable fluids such as petroleum or highly toxic fluids such as chemicals. If a leakage of the transferred fluid occurs due to failure of the 7-lunge, pulp, etc., there is a danger that it will lead to a serious disaster. Therefore, in such a pipeline, it is necessary to detect leakage of the transferred fluid early and reliably without malfunction.

The object of the present invention is to provide a pipeline leakage detection method and apparatus that can satisfy the above-mentioned requirements.

A feature of this invention is that a large number of pressure detection points are provided at intervals in a pipeline, the time rate of change in pressure at these pressure detection points is measured, and the rate of change in pressure over time is set at adjacent pressure detection points. The time difference when the pressure exceeds this value is measured, and when the ratio of this time difference and the set time determined by the distance between the pressure detection points becomes approximately the same, it is determined that there is a leak, and the leak is detected at an early stage.
And it can be detected reliably without malfunction.

The present invention will be described below based on an illustrated embodiment. As shown in FIG. 1, a delivery tank 2 and a pressure feeder 3 are installed on the upstream side of the pipeline 1, and a receiving tank 4 is installed on the downstream side.

Such a pipeline 1 is provided with a large number of pressure detection points H, %B1, . ,H
n is placed. This pressure detector detects the pressure of the transferred fluid at the pressure detection point, and corresponding pressure signals P., Pl, . In this time change rate device 5, the pressure signal is a time change rate signal ap.
/it and input to the comparator 6. The comparator 6 compares the setting value of the setting device 7 with dP/(lt, and when d≠t becomes large, outputs an output signal to the OR circuit 8 and the MuMD circuit 9. The output signal ' of the comparator at the pressure detection point of RS is also input to the circuit 9.
D circuit! It is connected to a timer 10 such as an expanded timer, and the timer 10 is activated by the output signal of the OR circuit 8, and the AMI
) It is designed to be stopped by the output signal of the circuit 9. The output signal of such a timer 10, that is, the time difference T
is input to the comparator 11. In this comparator 11, the setting time To (" L
/a), and if the ratio of these times is comparable, the comparator 11 outputs an output signal to the alarm 12. In this embodiment, one pressure detection point is paired with an adjacent pressure detection point on the downstream side, but it may also be paired with an adjacent pressure detection point on the upstream side. The output signal of the point comparator 6 is the recorder 1
5.

In such a pipeline, as shown in FIG. 2, when there is no leakage, the pressure distribution in a steady state shows almost no fluctuation in K as shown by the solid line. Next, when a leak occurs at point K1, a pressure drop occurs in proportion to the amount of leakage at this point, and a negative pressure wave is generated on both the upstream and downstream sides of the pipeline starting from point KX, with a pressure propagation speed a propagate with After 11 seconds of leakage, a negative pressure wave propagates for a distance of (t, xa) and the pressure distribution becomes like a wavy line.
%” After 1 second, it will look like a dashed line.

Such a leakage point Kx is between X and No. 1! .

Assuming that the time change rate of H, becomes large and exceeds the set value, as shown in FIG. The time rate of change exceeds the set value and the timer 10 is stopped by the circuit 9.

The time difference t between this and x4 is the set time T
12 alarms do not work because the alarm is very different from the above. continue,
It operates in the same way between x and X, and between ``4 and X,''
Since the time difference T here is almost equal to the set time To, the comparison @11 activates the alarm 12 to notify the leakage. In this way, alarms are issued one after another. This increases the interval in which leakage occurs to 411!4.

Furthermore, since the operating time of the comparator 6 is recorded in the recorder 13 as shown in FIG. 4, the leak position can also be determined based on the display time difference t between H4 and H4. That is, if the distance between the 5 points and the K1 point is LX, then 4-a-t XJ! = −.

With the above-mentioned detection device, it is possible to detect a leak at any point in the pipeline and also know the location of the leak.In addition, the comparator 6.11 doubles the prevention of malfunction. ◎ As mentioned above) According to the leak detection method and device according to the present invention, leaks can be detected early and reliably without malfunction due to the relatively simple configuration. It is possible to detect

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the outline of the pipeline, Fig. 2 is a graph showing the pressure distribution of the pipe 2-in, Fig. 3 is a circuit diagram showing a detection device according to the present invention, and Fig. 4 is a diagram of a similar device. It is a graph showing the operating status. 1. Pipeline, 2. Sending side tank, 3. Pressure feeding machine, 4. Receiving side tank, 5. Time change rate device %6...
Comparator, 7... Time change rate setting device, 8... OR circuit, 9
...AND circuit, 109 @ timer, 11-- comparator,
12... Alarm, 13... Recorder, 14... Time setting device, K... Pressure detection point, H... Pressure detector. Patent applicant: Sumitomo Metal Industries, Ltd. Figure 1, Figure 3L4

Claims (1)

[Claims] (A large number of pressure detection points are provided at intervals in the pipeline that transports the IJ 8 bodies, and the time rate of change in pressure at these pressure detection points is measured. A pipeline characterized by measuring the time difference when the time rate of change in pressure exceeds a set value, and determining that there is a leak when the ratio of this time difference and the set time determined by the distance between pressure detection points is about the same, and 9:00. (2) The leak position is detected from the time difference when the time rate of change of the pressure exceeds a set value at adjacent pressure detection points sandwiching the leak point and the pressure propagation velocity due to the leak. A pipeline leak detection method according to claim 11g1, characterized in that a large number of pressure detectors are arranged at intervals in a pipeline that transfers a fluid, and the pressure signals of the pressure detectors are detected over time. A time change rate device that converts the change rate into a rate of change, a comparator that compares this time change rate with a set value, an OR circuit into which the output signal of the adjacent comparator is input, and an iD circuit and an OR circuit. 〉How it works: A timer that is stopped by the ND circuit, a comparator that compares the output value of this timer with a set value determined by the distance between the pressure detectors, and a comparator that is activated by the output signal of this comparator. 1. A leakage detection system for a pipeline, comprising: an alarm; and a recorder into which the output signal from the time rate of change comparator is input.