JPS58131532A - Detection of accident of liquid feeding pipe - Google Patents

Abstract

PURPOSE:To distinguish burst accident from crush accident to detect the accident of a liquid feeding pipe highly accurately by using time series data of two discrimination formulas. CONSTITUTION:Manometers 1301, 1302 and flow meters 1401, 1402 are attached to both the ends of the liquid feeding pipe 1 and a pressure value and a flow rate value measured at a period are accumulated in a data storage device 16. The values of two discrimination formulas are found from the present measured value and the measured value at a past time corresponding to the time required for the transmission of the requid between two measuring points of the liquid feeding pipe 1 out of said stored measurement data, and whether the liquid feeding pipe 1 is normal or not is discriminated by the values of the two discrimination formulas. When an accident is discriminated, the position of the accident is found from the time shearing of the time series data in the two discrimination formulas to discriminate whether the accident in the pipe 1 is burst or crush by a data processor 17.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting an accident in a liquid delivery pipeline.

Conventionally, there was a device for this purpose as shown in Fig. 1. In the figure, (1) is the liquid pipe, (2) is the rupture point of the liquid pipe (1), and (61) to (6s) are distributed in the axial direction of the liquid pipe (1). ll to detect that the pressure of the first . The second and sixth six detectors, (41) to (4,) are each detector (6,) to (6,
,), a frequency phase-shifting transmitter, (5), which is provided corresponding to the Narita drop and moves the center frequency of the carrier wave in accordance with the Narita drop.

(6), (γ) is the first. These are the second and sixth detection devices, both of which are composed of measuring instruments in the axial direction of the pipe (1), that is, a detector (3) and a frequency phase shift transmission W#t4). t8L(9) sun is the first. Second and sixth sensing devices (5).

Signal transmission lines corresponding to (6) and (7), (11) are receivers for signals sent from each frequency phase shift transmitter (4,) to (4m), and (2) is a receiver for signals sent from each frequency phase shift transmitter (4,) to (4m). A display means for displaying the output as a function of time, such as a pen recorder.

Next, the operation will be explained.

When a rupture occurs at a certain point (2) in the liquid pipe (1), an instantaneous pressure drop occurs, which propagates in the axial direction at the speed of sound, a well-known property of compressible fluids. It is. Now, the wave propagation of the pressure drop generated at point (2) is first transmitted to the second detection device (6), then to the sixth detection device ffi.
(7), and finally reaches the first detection device (5). At this time, each detector (3+) to (31) detects that the pressure in the liquid feeding pipe f1) has decreased compared to the normal value, and each frequency phase shift transmission i1 (4) to (43) , moves the center frequency of the carrier wave in proportion to the detected falling pressure and sends it to the receiver (11). When the receiver (1υ) receives this, it sends the output to the pen recorder, so in the pen recorder (b), there are six detection devices (11, 2nd and 6th) (5).
, [6) and (7), the moment of pressure drop is displayed with time as the horizontal axis. At this time, the rupture point (2) of the liquid feeding pipe (1) is determined from the time difference τ of pressure drop, and the rupture position is determined by d=D−c·τ/2. Here, D is the distance between the second detector (3g) and the fifth detector (3g), 0 is the speed of sound, and d is the distance from the second detector (c5m) to point (2). It is.

The conventional method for detecting an accident in a liquid transfer pipe is configured as described above, so that in the case of an accident in which a liquid transfer pipe collapses, a pressure drop occurs on the downstream side, and a pressure increase occurs on the upstream side. Only the detector on the downstream side is activated, which has the disadvantage of erroneously detecting the state of an accident. In addition, in the case of a rupture accident of a liquid pipe, the pressure drop propagates both upstream and downstream from the rupture point, but there is a phenomenon in which it is reflected again at the end and propagates back, and these waves increase in width. Since complicated pressure fluctuations tend to occur due to the grooves, conventional methods cannot cope with this problem.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional method, and since abnormal fluctuations in pressure or flow rate propagate at the full speed of sound in the liquid, there is no constant difference between the pressure or flow rate at both ends of the liquid sending pipe. By focusing on a relational expression that holds equally true and using a discriminant derived from this relational expression, it is possible to measure both pressure drop and pressure rise, and detect not only rupture accidents but also crushing accidents, and also detect pressure or flow rate. It is an object of the present invention to provide a method for detecting an accident in a liquid sending pipe that can accurately detect an accident in a liquid sending pipe in response to complex pressure fluctuations that occur due to the reflection of fluctuation waves.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of a device used in the method for detecting an accident in a liquid delivery pipeline according to the present invention, and the same parts as in FIG.

In the same figure, (131) and (131) are the liquid sending pipe (1)
The first and second pressure gauges (
130+), signals from (130y), (14), (1
4) are the signals from the first and second flow bell meters (1401) and (140) installed at the leak of the liquid pipe (1), respectively, and (15+) and (15) are these signals. (16*) and (16 Yuki) are data storage devices that also serve as receivers for the above signals, (B) is a data processing device, and (E) is the processed result. This display device (e) displays, for example, the one shown in the figure. In other words, if a rupture occurs in the liquid supply pipe, the location of the accident point is displayed to the user along with the accident probability. In the figure, A and B indicate the positions of measurement points, and 1 indicates the position of the accident point.

Next, the accident detection method of this invention will be explained.

In general, a liquid pumped through a pipe is treated as a compressible fluid, so the pressure p(x,
t) or the flow rate q(x, t) is expressed by the following equation as is well known.

q(x, t)=-wan(y(t-1-)-t(t--)
)...(2)OOG Here? (t+-) is the backward wave component that propagates from downstream to upstream -r(t-1) is the first wave component that propagates from upstream to downstream, D is the cross-sectional area of the liquid flowing in the pipe, and g is the force D (l
Velocity -〇 is the propagation speed of the wave, which is equal to the speed of sound propagating in the liquid.
Assuming that the distance 1ill of measurement point B is 1, the time T for the wave to propagate between these two points is τ=i/o.

(1), t2), x = Q or x
By substituting the value of = j and considering τ=i10f, the following equations (8) and (4) are obtained.

p A(t-τ)-1-k-q A(t-τ)=
p Bjte+ @ q n(t) ...(3)P
A(t←EC”qA(t)=pB(−τ)−k・C
IB(-τ) ... (4) Here, corresponding to distance 40, subscript A is distance! It is represented by the subscript B corresponding to . Further, k is a constant and k = o / gD.

Equation (3) is calculated from the measurement point A on the left side of the liquid supply pipe in Fig.
The sum of the pressure and flow values measured at -pA(t-τ)+ and -qA(t-τ) are the pressure and flow rate measured at point B on the right side of the liquid sending pipe after time τ. The sum of 1 ton of p n(t)+
This shows that -(LB(t)) is equal to (4)
Similarly, the equation is the difference between pressure and flow rate at point A PA(t)-k-q
h(t) is the difference between the measured pressure and flow rate E1B(i-τ)-
k'' (iB (t-d)).

Now, in the method of the present invention, based on the above equations (3) and (4), a determination is made to determine the state of the liquid supply pipe, that is, whether it is normal or an accident, from these equations (B) and (4). This paper provides a method for deriving a formula and using the formula to accurately detect accidents in the pipeline. In other words, measurement data collected from time to time and data storage devices) k: 116
λ(t)=p ), (
t-τ)+ to −qA(t-τ) −p n(t)− to −
+L n(t)...(5)μ(t¥=p A(t)-
k I (i A(t)-p B (t-τ)+ -q
B(tr)...(6) The discriminants λ(1) and μ(1
) and make the following determination.

(1) , 111&X(Iλ(t)l , l μ(
t)l)≦−Naraba normal ・+71 value), max(
lλ(1, lμ(t,)l )>g fx There is a mule accident, and the accident type is λ(→−μ−μ)×δ, then it is a crushing accident...(8
) If λ(1)-μ(1)≧δ, then rupture accident...
- Determine (9).

Here, C1δ is a constant determined by considering the properties of the target pipe and liquid.

If λ(1) or μ(1) in (I) is smaller than the paddle, that is, it is zero in the above equations (5) * (6), but considering measurement errors, frictional pressure loss, etc., a certain tolerance range can be set. If the setting is within the range s, it is determined to be normal, and otherwise it is determined that the above (It) accident has occurred. Next, if it is determined to be an accident, it is classified into both collapse and rupture, with the former being a case in which there is no leakage, and the latter being a case in which there is a leakage.

Figure 6 shows the wave propagation of pressure or flow rate at the time of a transmission line accident. Assume that there are measurement points at points A and B of the conduit, and an accident occurs at one point that is a distance #ld from measurement point A.

In addition, the horizontal axis represents distance and the vertical axis represents time. The solid line (4) represents a forward wave that travels in the direction of liquid flow, and the line represents a backward wave that travels in the opposite direction to the flow direction. Fluctuations in pressure or flow rate represent velocity. Since the relational expressions (1) and (2) of wave propagation hold between the 0 point A1 and the point 10 which propagate at O, we obtain the following equation (1υ).At present time tn1 Then, it takes time T1. to pass through one point and reach point B, while the backward wave passing through one point at time tn takes T1.
Suppose that point A is reached in a time of .

λ (tn + τm ) = jlr (tn) + kJqy (tn
) −an) μ(tn+y+ )=Δhy(tn
) - Δq y (t n ) - (11) Here, Δhy (tn) is the pressure difference between the point immediately before and after the accident point 1, and Δ(L p (t n ) is the pressure difference between the point immediately before and after the accident point 1. This is the flow rate difference between the point immediately before and the point immediately after point 1, that is, the leakage current accompanying the rupture.When the accident is a crushing and there is no leakage, Δqy
(tn) is zero. Furthermore, in the case of a bursting accident, the above C1 is smaller than that in a crushing accident.

In the normal case without any accidents, Δhy(tn); 0. Δq
Since y(tn)=Q, the above equation and (11)
Each expression is zero. Now, in the case of a bursting accident, Δ
As h7 (t, n) = 0, λ (tn + τ,) = -
Since μ (tn + τ1), if we replace it as 1 = 1 n + τ1, we get λ (t + τ).

−T1) knee μ(1), therefore it can be seen that λ and 1 μ have equal values with time delay=−−T1. From this time difference -T, -d, the distance d to the accident point 1 can be found as ts=ct-o·)/2. On the other hand, in the case of a crushing accident, Δqy(tn)=Oj−L, Te,
Since λ(tn+τ,)=μ(tn+τ1), t=
Rewriting it as tn + τ1, we get λ(t+τ, -T1
)=μ(1). Therefore, the time difference between λ and μ is = τ, -
It can be seen that they have equal values for τ1. This time difference = τ1
The distance d from −τ1 to accident point 1 is a=(j−0・)/2
is required. In the embodiment, the time difference between λ and μ is determined by comparing time series data of their absolute values 1λ1 and 1 μm so that it can be applied to both bursting accidents and crushing accidents.

Summarizing the above description, the operation of carrying out the present invention will be explained with reference to FIG.

Pressure p A (t) at measurement point A (Fig. 6), flow rate (L A
(t) and the pressure p m(t) at measurement point B in FIG.
q''(t) is sent to the data storage device 0 at a period of Δt, and in this data storage device aI, the respective measured data time series pat), p^( are read),..., q
Bet), qa(see,・・・・・・-pm(t)
, Pa(t-at), ・-・-・-, qs(t)
, qs(t-41,... are stored sequentially (
Processing step 401). Next, a discriminant function 1(t), At> is calculated for each period Δt, and this data time series is expressed as λ(t), λ(t), λ(t-2Δs,...
, λ(t−rΔt).

......, Su (wo - Buddhari and Xt), μ (wo 屹t
), μ(planted).

μ(t-2Δt),..., μ(1=Δs,...
..., μ(t-nΔ) (processing step 402
). That is, at time t, the past net data is stored as a time series in the current time values λ(1) and mt). Now, as for the contents of the process, if λ (R or At) is small (formula (7)), it is determined that the conduit is normal (judgment step 403). next,(
A) If the equation is not satisfied, it is an accident, and the type of accident, that is, whether it is a crushing accident or a bursting accident, is determined according to equations (8) and (9) (judgment step 404). At this time,
From the pattern of time series data of two discriminant functions λ and μ,
The time difference between the two, t=-11, is also calculated, and the distance d to the accident point F is calculated as ((1-0(h-jt))/2 (processing steps 405 and 406).In the case of a rupture accident, the leakage flow rate is Δqr is calculated (processing step 407), and in the case of a crushing accident, the pressure drop amount ``r'' is calculated (processing step 40).
8). Figure 5 shows the discriminant, the absolute value μm of each of λ and μ.
, shows an example of time series data of 1 μm.

The past t-nΔ from the current time t is determined based on data up to the time before. In the early days, the value of Iil, 1μm is small and the pipe is determined to be normal, but when an accident occurs, the value of 1λ1
．． Since both change by 1 μm, it is judged as an accident.

Whether the accident is a rupture or a crushing is determined by λ(t)−At>
It is determined by ≦δ. Next, by comparing the time series patterns of 1s 1 and 1 μm, the time shift between 1s 1 and 1 μm is determined. In the example shown in Figure 5, 7=3Δt, and the distance to the accident point is d
It is obtained as =(1-5·Δt·0)/2. When it is determined that it is a crushing accident, -chi r7 (”(t) + Xt
)), the pressure drop is determined, and when a bursting accident is determined, K is Δq""i'λ(t)-mt, and the leakage flow rate is determined.

As described above, according to the present invention, since the time series data of two discriminants are used, it is possible to distinguish between a crushing accident and a bursting accident, and the wave motion caused by the accident is reflected and the measured pressure and flow rate are Even if there are fluctuations, it is possible to detect accidents in the liquid supply pipeline with high accuracy.

[Brief explanation of drawings]

Figure 1 is a block diagram of a device used in a conventional method for detecting accidents in liquid delivery pipelines. Figure 2 is a block diagram of a device used in the method for detecting accidents in liquid pipelines according to an embodiment of the present invention, and Figure 3 shows a discriminant used in the method for detecting accidents in liquid pipelines according to an embodiment of the present invention. 4 is an explanatory diagram of wave propagation. FIG. 4 is an explanatory diagram of an accident determination method in an accident detection method for a liquid pipe line according to an embodiment of the present invention. Figures 11 and 5 are diagrams showing a liquid pipe line according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of time-series data of values of two discriminants used in the accident detection method of FIG. (1) Liquid feed pipe line, (2)...Rupture point - (13t),
(13g)...Signal from pressure gauge, (141)-(1
4g)...Signal from flowmeter, (15t). (15t)... Signal transmitting device, Korea... Data storage device, a... Signal receiving and data processing device, (
To)...Display device for data processing results, (6)...Locus of forward wave component propagating in liquid, 4...Locus of backward wave propagating in liquid, ("0x) - (1501) )...
Pressure gauge, (140t), (140t)...flow meter. Note that the same reference numerals in Figure 1 indicate the same or equivalent parts. Agent Makoto Kuzuno (1 other person) Figure 1 12 Figure 2 Figure 3 179- Figure 4

Claims (1)

[Claims] (1) A pressure gauge and a flow meter are installed at both ends of the liquid supply pipe, and the pressure value and flow rate value measured in a certain period are accumulated in the data storage Md, and among this stored measurement data, the current time The values of two discriminants are calculated from the measured value of It is determined whether the liquid pipeline is normal or not, and when it is determined that it is an accident, the location where the accident occurred is located from the time lag of the time series data of the two discriminant formulas, and it is determined that it is a pipeline collapse accident. 1. A method for detecting an accident in a liquid supply pipe, the method comprising determining whether the accident has occurred or a rupture accident has occurred.