SU877329A1 - Turbine flowmeter for electroconductive liquid - Google Patents

Description

(54) TURBINE FLOW METER FOR ELECTRICAL WIRING LIQUIDS

one

The invention relates to the measurement of the flow rate of electrically conductive liquids, in particular, to devices for measuring low flow rates, for example, in hydrogeological investigations of drilling wells.

A device for measuring velocity and flow rate, a housing with an impeller placed in it, a movable pair of electrodes placed on the chip at real distance x from its axis, a fixed pair of electrodes placed on the housing and connected to a DC source and measuring an instrument, such as an oscilloscope;

The flow rate in this device is determined by the number of pulses of the component of the current flowing through the moving electrodes of the blade when they approach the stationary electrodes as the impeller rotates. The number of revolutions of the impeller per unit of time is proportional to the consumption of the liquid i

bones. The ratio of the amplitudes of the two nearest pulses determines the direction of rotation.

The known device cannot be used when measuring small flow rates of a liquid with a high degree of mineralization due to the presence of interference, the higher the degree of mineralization of the liquid, the higher the level of which is. These interferences are due to a change in the current component passing through an electrically conductive line and a fixed pair of electrodes due to a change in the conductivity of the liquid. The amplitude of interference can be equal to and exceed the amplitude of the useful signal that carries information about the flow rate and direction, which makes it impossible to measure with a high degree of mineralization of the liquid (more than 10 g / l NaCV in the composition).

A turbine flowmeter for electrically conductive liquids is known, comprising a cylindrical body with a stationary pair of electrodes located on its wall, an impeller rotatably mounted therein with a second pair of electrodes located on it, a frequency generator, the output of which is connected to a stationary electrode pair, and a recording unit with a pulse shaper at its input. The flow rate in a known device is determined by the number of pulses, the component of the current flowing through the moving pair of electrodes. electrically conductive fluid when the impeller rotates 2. This device is impossible. “Use with a high degree of mineralization of the fluid (more than 10 g / l) This is due to the presence of a surplus (in amplitude, useful signal of interference arising from sharp fluctuations of conductivity beyond the impeller's turn. stationary and movable electrodes change due to fluctuations in the degree of mineralization in the measurement process, as well as due to the formation (with a high degree of mineralization of gas bubbles deposited on ited x electrodes. In the known device, the determination of the direction of rotation is also not provided. The purpose of the invention is to reduce the influence of the conductivity of a liquid on the measurement accuracy and to make it possible to determine the direction of movement of the liquid. The goal is achieved by the fact that, in a turbine flow meter for electrically conductive liquids, comprising a cylindrical body with a stationary pair of electrodes located on its wall, an impeller mounted in it with the possibility of rotation, a second pair of electrodes located on it, a frequency generator, the output of which is connected to a stationary a pair of electrodes, and a registration unit with a pulse shaper at its input, a low-pass filter is additionally introduced, the input of which is connected to stationary electrodes, and the output is connected to the unit m registration, the electrodes being arranged on the impeller are interconnected by a diode. In addition, an integrating device and a voltage polarity indicator are added to the registration unit, the input of the integrating device is connected via a shaper WITH THE OUTPUT of the low-pass filter, and the output is connected to the input of the voltage indicator polarity. The introduction of a diode placed on the impeller into the flowmeter and connected between the electrodes of the moving pair provides the input low-pass filter to the input of the detected useful alternating current component flowing from the frequency generator through the diode and the moving electrodes as the impeller rotates. The frequency of the pulses of this component is proportional to the flow rate of the fluid. The pulses of the useful component are fed to the input of the low-pass filter in the form of separated asymmetrical pulses only positive or only negative polarity (depending on the direction of the diode) and separated at the output of the filter. Another component of the alternating current flowing through the electrically conductive fluid and stationary electrodes and causing the presence of interference enters the input of the low-pass filter in the form of non-detected, symmetrical positive and negative half-waves, which are eliminated by algebraic summation in the filter the output of the low-pass filter to the input of the registration unit receives positive and negative pulses only of the component of the current that occurs during the rotation of the crystal and carries Suitable information on consumption. In addition, the introduction of a diode placed on the core and connected between the electrodes of the mobile pair, together with the introduction of an integrating device and a polarity indicator into the registration unit, makes it possible to simultaneously measure the direction of rotation of the impeller, i.e. flow direction. This is due to the fact that at each turn of the blade the polarity of the diode switching on to the input of the lower frequency filter changes, as a result of which the current pulses flowing through the electrodes of the moving pair have different polarity. In the order of pulses with different polarity, the direction of rotation of the impeller is determined. FIG. 1 shows a block diagram of a device for serially connecting a low-pass filter with an electronic,

childbirth of a fixed pair; in fig. 2 the same, with parallel connection; in fig. 3 - stress graphs.

The flow meter includes a housing 1 filled with an electrically conductive liquid 2 in which the crust 3 is placed. On the surface of the crutch 3 made of an electrically insulating material, there are electrodes 4 of a moving pair. A diode 5 connected between electrodes 4 is mounted into the impeller body 3. Case 1 is made of conductive material and is one of the electrodes of the stationary pair, the other electrode 6 of the stationary pair is located on the case 1 and is isolated from it. One output of the generator 7 (for example with a frequency of 800 Hz) is connected to the electrode 6, and the other through the input resistance of the low-pass filter 8 to the housing 1. The low-pass filter 8 is inductively capacitive with a passband from 0 to 200 Hz. The registration unit 9 consists of a two-threshold pulse generator 10 which is made, for example, in the form of a differential amplifier with positive feedback, a pulse counter 11, an integrating device 12 and a voltage polarity indicator 13. A microammeter with a symmetric scale was used as the indicator 13 of the polarity of the voltage. The output of the low-pass filter 8 is connected via a pulse shaper 10 to the input of a pulse counter 11 and an input of the integrating device 12. The output of the integrating device 12 is connected to a voltage indicator 13 of the voltage

The device works as follows.

Under the action of the flow of electrically conductive fluid 2 flowing through the casing I of the flow meter, the impeller 3 begins to rotate. When the impeller 3 rotates, the moving pair electrodes 4 alternately pass near the fixed electrode 6. In this case, a current flows through the moving pair electrons 4. The input of the low-pass filter 8 receives a signal consisting of a useful signal arising during the rotation of the curtain 3, and an interference signal, formed due to sharp oscillations of the current component flowing through the electrically conductive liquid, the fixed electrode 6 and the housing 1 for a period of one

rotation of the impeller (nastot rotation of the little cloth 0.005-30 s). The interference signal has the form of symmetrically located opposite polarity pulses 14,

which are algebraically summed on the low pass filter 8, are mutually destroyed. As a result, only pulses 15, which occur during rotation of the impeller 3 and determine the magnitude of the fluid flow, arrive at the registration block 9 from the output of the filter 8. When the impeller 3 rotates clockwise from the position at the moment t, put the 1st pulse

15 (Fig.30). After a quarter of a turn, when the electrodes are rotated by 90, negative impulses 15 occur, since in this case diode 5 will change the polarity with respect to the fixed ones.

electrodes 6 and the housing 1. When rotated clockwise, the first of the two nearest pulses will be positive (Fig.35). In this case, at the output of the driver 10 pulses, the signal has

the form shown in fig.ZV. From the graphics, it is clear that a positive jpi pulse has a longer duration, than negative. At the output of the integrating device I2 in this case, a positive voltage is generated. Fig. 3g, under the action of which the arrow of the indicator 13 is deflected to the right (not shown).

During the rotation of the crutch in the opposite direction, a negative impulse is first induced (fig.ZE). In this case, the negative pulse at the output of the pulse driver 10 has a longer duration (Fig. Ze). A negative voltage is generated at the output of the integrating device 12. The arrow of indicator 13 is deflected to the left.

In another embodiment (Fig. 2), the electrodes of the fixed pair are located on the inner surface of the housing 1, made of an electrically insulating material, and are interconnected. The angular displacement between the electrodes 6 and each of

of electrodes 6 is chosen over O

and less than 180 (from the condition of determining the direction of rotation).

Claims (2)

Figure 2 shows the angular displacement equal to 90 °. The low pass filter is connected in parallel with the electrodes 6 and b of a fixed pair. In this case, a resistor 16 is included in the generator 7 circuit. The use of the proposed invention provides a wider area of use for the device, namely, it enables to conduct hydrogeological studies of drilling wells with a degree of mineralization of the liquid up to 30 g / l, 3 times the value at which The known flow meter. In addition, the proposed flow meter provides simultaneous determination of the direction of fluid flow. These advantages provide a more accurate accounting of groundwater reserves, which is the reason for the economic effect. Claim 1. Turbine-type flowmeter for electro-conducting liquids, comprising a cylindrical housing with a stationary pair of elec- trons on its wall, an impeller mounted for rotation with a second pair of electrodes located on it, a frequency generator whose output is connected to a stationary a pair of electrodes, and a registration unit with a pulse shaping device at its input, characterized in that, in order to reduce the effect of the conductivity of the liquid on the measurement accuracy, a filter is added to it lowpass whose input is connected to the fixed electrodes, and an output - a recording unit, wherein the electrodes are arranged on the impeller, connected IU zdu a diode. 2. Flowmeter pop. 1, characterized in that in order to enable determination of the direction of fluid movement, an integrating device and a voltage polarity indicator are additionally introduced into the registration unit, the input of the integrating device is connected to the low-pass filter output through the driver, and input polarity indicator voltage. Sources of information taken into account in the examination 1. The author's certificate of the USSR 249795, cl. G 01 R 05/06, 1969. 2.Katys G.P. Volumetric flow meters. M., Energie, 1965, p. 13-14 (prototype). f / It 13 IS 1S A V A A V l d V