RU172081U1 - TENZOR RESISTANT PIPELINE DIAGNOSTIC SENSOR - Google Patents

Abstract

The utility model relates to pipeline transport and is intended to diagnose the condition of the pipeline. Expands the arsenal of hardware. The strain gauge bellows sensor for diagnosing the condition of the pipeline consists of a sealed housing in which the bellows is vertically placed, to which one ends of the strain gauges are attached to the blind upper base, the second ends are connected to the tension devices through the lubricators of the tight chamber, the bellows is sealed to the lower open base with the lower base of the sealed enclosure, the cavities of the sealed enclosure and the bellows are connected by fittings to a controlled pipeline, and on An alternating choke is installed on the bellows connected to the bellows. The technical result is the expansion of functionality, increasing the sensitivity and reliability of the sensor, the possibility of continuous monitoring of the state of the pipeline, improving the reliability of diagnostics of the state of pipelines. 2 ill.

Description

The utility model relates to pipeline transport and is intended to diagnose the condition of the pipeline. Expands the arsenal of hardware.

A well-known underground communications defect sensor containing a shell, in the lower part of which there is a membrane on which a piezoelectric element pressed against it is located, and a cover connected to the shell, a holder in the form of a tube is built into the cover, at the ends of which electromagnetic antennas spaced apart at a basic distance from each other, and the conclusions from electromagnetic antennas and piezoelectric elements are connected to the calculator [Patent RU No. 2408859, IPC G01M 3/24. Sensor for finding a defect in underground communication / S.S. Sergeev (RU). - 2009106367; Announced February 24, 2009; Publ. 01/10/2011; Bull. No. 1], which has low sensitivity, due to the fact that the reception of signals is through a layer of soil in which the signal attenuation occurs; the inability to monitor the state of the pipeline in automatic mode.

Currently, the place of damage to the pipeline in the form of leakage is determined mainly by the measured pressure drop by technical (electrical) pressure gauges installed along the pipeline route and having, due to the high operating pressure of pumping hydrocarbons, a high reduced error, as a result of which it is not possible determine the location of medium or small leaks, as well as the pressure gauges formed at a considerable distance from the installation site; requires very frequent installation of pressure gauges along the pipeline route, which reduces the effectiveness of leak detection systems [Kutukov S.E. The problem of increasing the sensitivity, reliability and speed of leak detection systems in pipelines // Oil and gas business. - 2004. - T. 2. - S. 29-45; Dughman J.S. Acoustic used to inspect 36-inch natural gas line. Pipe Line Industry. - 1984, 61, No. 2, P. 46-50].

A pipeline damage sensor is also known, comprising a membrane with a piezoelectric element fixed on it, the membrane being placed in a blind pipe behind a shut-off element, forming a sealed chamber attached to a controlled pipeline, and forming two cavities communicating with each other by an adjustable throttle [Patent RU No. 114365 G01M 3 / 00 // Sensor of damage to pipelines // R.G. Sultanov, Ch.A. Yarullin et al., Publ. 03/20/2012; Bull. No. 8], taken as a prototype.

It is known that to increase the efficiency of using pipeline transport, the pumping pressure is increased, this leads to an increase not only in the amplitude of fluctuations in the working pressure during technological switching, but also in the amplitude of pressure fluctuations (noise), which leads to a significant decrease in the reliability of diagnosing the occurrence of minor damage due to the impossibility the selection of a useful signal by existing intelligent pressure sensors (Metran, Sapphire, etc.), thereby reducing or reducing the effect of CT application of intelligent diagnostic systems and existing pipeline diagnostics sensors (DDST).

In addition, this approach to the diagnosis of damage does not fully take into account the pressure fluctuations in the pipeline that occur during technological switching (start-stop of the pumps, a sharp increase - decrease in the selection of the transported product), especially when these disturbances occur near installed sensors, where the amplitude of the disturbance pulse is still sufficient great. The closer the sensor is to the location of the disturbance, the greater the amplitude of the disturbance pulse, and the steeper the front of the disturbance pulse, and as the distance from the installation site of the sensor from the disturbance due to hydraulic friction, both the amplitude of the pulse and the slope of the pulse front decrease, which makes it difficult to differentiate damage from disturbance.

This difficulty can be eliminated by using, as a controlled parameter, the rate of change of momentum or the trend of pressure change, i.e. pulse fronts and comparing them with the given ones.

In addition, only leaks are diagnosed by the existing method, while at the same time, other violations of the operating mode, such as complete or incomplete blockage of the working section of the pipeline, which also need to be diagnosed, preferably by the same technical means, often occur in pipeline transport.

The objective of the utility model is to expand the functionality, increase the sensitivity and reliability of the sensor, the possibility of continuous monitoring of the state of the pipeline, increase the reliability of diagnostics of the state of pipelines.

The problem is solved by a strain gauge bellows sensor for diagnosing the state of the pipeline, consisting of a sealed chamber, characterized in that the bellows is vertically placed in the sealed enclosure, to which one ends of the strain gages (TP) are attached from the outside and inside, the second ends are brought out through the lubricators of the sealed chamber on the tensioning device, the bellows lower open base hermetically connected to the lower base of the sealed chamber, the cavity of the sealed chamber and the bellows is connected pipe fittings controlled, wherein on the nozzle connected to the bellows, an adjustable throttle.

A sensor for diagnosing the condition of the pipeline, illustrated by drawing 1, is proposed.

DDST consists of a sealed housing 3, a bellows 2 is vertically placed inside the sealed chamber. One ends of the strain gauges 4 and 5 are attached to the deaf upper base of the bellows 3 from the outer and inner sides, the second ends of the strain gages through the lubricators (not shown) of the hermetic chamber are connected to tensioning devices ( not shown), the bellows lower open base hermetically connected to the lower base of the sealed housing, the cavity of the sealed housing and the bellows are connected by fittings with a controlled pipeline, and on An adapter connected to the bellows is fitted with an adjustable choke 1.

We assume that with a sharp change in pressure in the pipeline, characteristic of damage to the pipeline, the sensor does not have time to exchange heat with the environment. Therefore, thermal processes in the sensor can be considered quasistationary and using the gas equation of state for the sensor inside the bellows, we obtain

where p is the pressure in the pipeline at the next time;

V0 is the initial volume of the bellows;

V is the volume of the bellows at the next point in time.

Moreover

where Δ V is the change in the volume of the bellows.

A change in the height of the bellows is characterized by a change in the value of the electrical resistance of the strain gauge Δ R

where α is the linear coefficient of proportionality,

S is the area of the bellows.

за время Δt можно судить о величине тренда (крутизны фронта импульса) и о возможных неисправностях. Подставляя (2), (3) в (1), получим выражение для определения давления в трубопроводе

In the sensor, when the pressure in the pipeline changes by Δ p by the change in momentum

over time Δ t, one can judge the magnitude of the trend (the steepness of the pulse front) and possible malfunctions. Substituting (2), (3) in (1), we obtain the expression for determining the pressure in the pipeline

or

Thus, the change in pressure pulse

Changing the sign of the pulse indicates the type of damage (clogging - leakage). It is proposed to compare the slope of the pressure pulse front with a predetermined one, which is a stochastic change in pressure in the pipeline, as well as with the pressure change associated with a change in the operating mode of the pipeline, and when the slope of the pressure pulse exceeds the specified slope of the pressure front, they indicate damage, and they say the excess sign - about the type of malfunction (leak or clogging).

Strain sensors, especially semiconductor, have a high temperature dependence, significantly affecting:

1) the resistivity of the material of the strain gauge ρ (T);

2) longitudinal strain approximated by a linear function

b (T) = β (T-T0) ;

3) the difference between the temperature extensions of the sensor and the substrate.

In addition, load cells have differences in the transfer characteristics of each TP in one batch.

As a result, even in the absence of a mechanical effect on the strain gauge, its resistance changes with temperature (T-T0) and the effect of the apparent strain b (l) = b (T) / KT , where KT is the coefficient of strain sensitivity, arises.

To increase the accuracy of measuring pressure in the pipeline system and to eliminate the systematic component of the error, the influence of temperature and mechanical factors (vibrations, displacements of the pipeline and the sensor), it is necessary to include strain gages in the adjacent shoulders of the measuring bridge, which will compensate for these disturbances.

To ensure the differential measurement principle, the wires of the strain gauges must be prestressed (stretched) by tensioning devices, which will allow measuring pressure changes with any sign. Before starting the measurement, the measuring bridge must be balanced, and the signal from the measuring diagonal is fed to the input of the ADC of the microcontroller, which has a large input impedance.

With increasing volume of the bellows, the strain gauge 4 is compressed, and 5 is stretched. In this case, the resistance of the strain gages are defined as

,

- сопротивление тензорезисторов перед началом измерений, ΔR - изменение сопротивления.Where

,

- resistance of strain gauges before the start of measurements, Δ R - change in resistance.

The change in resistance is determined by the measuring bridge

where R ₁ , R ₂ - the known resistance of the shoulders of the measuring bridge;

U is the voltage on the measuring diagonal;

U _pit - supply voltage

Formula (9) can be simplified in the form of a linear dependence

Where

и t заданные тренды изменения давления при утечках и закупорках будут заданы горизонтальными линиями (фигура 2), т.е.

, а сигнал, снимаемый с датчика при нормальном режиме работы трубопровода, будет находиться в коридоре между этими горизонтальными линиями. При выходе сигнала из этого коридора сверху или снизу (участок Δt) можно говорить об утечке или закупорке. Причем эти горизонтальные линии располагаются по обе стороны от оси абсцисс, т.к. производная может поменять знак, но на разном расстоянии в зависимости от уставки.In coordinates

and t, the set trends in pressure changes during leaks and blockages will be set by horizontal lines (Figure 2), i.e.

, and the signal taken from the sensor during normal operation of the pipeline will be in the corridor between these horizontal lines. When a signal exits from this corridor from above or from below (section Δ t ), we can talk about leakage or blockage. Moreover, these horizontal lines are located on both sides of the abscissa axis, because the derivative may change sign, but at different distances depending on the set point.

To increase reliability, given that the pressure change signal in the pipelines is of a stochastic nature, it is necessary to decide on the occurrence of damage if the specified alarm duration is exceeded.

If at some predetermined period of time a signal appears and disappears, then this case should not be diagnosed as an emergency, and the system starts again comparing the current signal with the given one.

Thus, comparing the change in pressure impulse (the steepness of the front of the pressure impulse) with the preset one can judge the presence of damage, and by the sign of the change in impulse it is possible to judge what kind of damage has occurred (leakage or blockage).

Claims (1)

A strain gauge bellows sensor for diagnosing the condition of the pipeline, consisting of a sealed chamber, characterized in that the bellows is vertically placed in the sealed enclosure, to which one ends of the strain gauges are attached from the outside and inside of the blind base, the second ends through the lubricators of the hermetic chamber are connected to tensioning devices, the bellows the lower open base is hermetically connected to the lower base of the sealed enclosure, the cavities of the sealed enclosure and the bellows are connected by fittings to the iruemym conduit, wherein on the nozzle connected to the bellows, an adjustable throttle.

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