A device for determining the liquid level in the tank


(57) Abstract:

The inventive device comprises at least three sensing elements 1, the pulse generator 2, the pulse receiver 3, an amplifier 4, an analog-to-digital Converter 5, block 6 calculations, the indicator 7. 1-2-3-4-5-6-7. 2 Il.

The invention relates to techniques for measuring non-electrical quantities and can be used to determine the position of the boundary of two immiscible liquids with different dielectric constant of the level and volume of liquids in containers of arbitrary shape.

The known device for the measurement of levels and boundaries of the division of environment (ed.St. N 1527505).

It is also known a device for measuring the storage level and temperature, liquids and gases of different density in the tank (France N 2624968) containing sensitive element in the form of delay lines, the generator and the receiver.

The disadvantages of these devices are the complexity of the scheme, the complexity of manufacturing the sensor element and the insufficient accuracy of measurement.

Closest to the proposed device is a device comprising a generator of sinusoidal napapansin in the form of two isolated from each other by wires (coaxial lines). This device works on the principle of radiointerference.

The main disadvantage of the device should be attributed primarily to the level measurement only in electrically conductive environments, nonlinearity, complexity of setup and operation, temperature dependence, the advanced setup when you change the physical properties of the liquid.

The aim of the invention is to expand the range of measured parameters controlled environments, improving the accuracy and reliability of the device, simplifying the design, manufacture and operation of the entire measurement cycle.

For this purpose, the sensor element is designed as two isolated from other conductors connected to the output of the high frequency pulse generator and the input of the receiver, the output of which is connected to the amp via a communication channel connected to a computing device, the output of which is connected to the indicator, which displays data showing the basic parameters of the level boundaries separating and volumes of immiscible liquids with different dielectric properties.

To ensure the possibility of measuring the volume levels, sections of immiscible fluids in dynamic conditions (fluctuations in p is g-friend and dispersed by the volume of the measured capacitance.

The principle of operation of the device is as follows.

Two insulated from each other and from the external environment of the conductor is lowered into a tank of immiscible liquids to full height. These conductors is sent to a high-frequency voltage pulse. The wave resistance (determined by the dielectric parameters of the environment), sent pulse is reflected. The reflected pulses received on the input line, distributed in time. The delay time of the reflected signal relative to the sent is proportional to the distance to the inhomogeneity of the wave resistance (the boundary between two media):

L = 1/2 v t , where L is the distance from the generator output to the border crossing;

v is the velocity distribution of the pulses in the conductors;

t is the time delay of the reflected signal relative to sent.

The factor 1/2 takes into account the dual path sent and the reflected signal. The number of reflected pulses is determined by the number of boundaries of media with different dielectric properties.

Comparative analysis with the prototype shows that the proposed device differs in that it contains sensitive e is th pulse generator and the input of the receiver, the output of which is connected to the amp via a communication channel connected to a computing device, the output of which is connected to the indicator, which displays the data level, separating and volumes of immiscible liquids with different dielectric properties.

And in terms of the fluctuations of the surface of the media device includes at least three sensor elements arranged parallel to each other and dispersed in the volume of the measured capacitance, and will allow you to consider (count) dynamic parameters of the liquid surface. Therefore, this device meets the criterion of "novelty". Comparison of the invention not only prototype, but also with other technical solutions, allows to conclude that the criterion of "substantial differences".

In Fig. 1 shows a functional diagram of the device for determining the volume levels and boundaries separating media of Fig.2 - the location in time sent and the reflected pulses, respectively.

The device contains sensitive element 1 in the form of two isolated from other conductors, one end of which is connected to the output pulses of the frequency generator 2 and the input of the receiver 3, the other is silical 4, the output of which through the channels 5 connection (analog-to-digital Converter) connected to the computing unit 6, the output of which is connected to the indicator 7. The communication channel is a high speed analog-to-digital Converter, a computation can be implemented on any PC, which includes the analog-to-digital Converter. In detail, the communication channel 5 and block 6, discussed in the book Figurnova C. E. IBM PC user, M.: Finance and statistics, 1991, S. 280.

The device operates as follows.

To determine the liquid level and the boundary line of the sensitive element 1 is dipped into the tank with controlled environments. The pulse sent by a high-frequency generator 2, while accepted by the receiver 3. The indicator is a momentum Uo(Fig.2). From this pulse count all other coordinates on the indicator 7. The first reflected pulse Ui(Fig.2) shows the time t of pulse passing through the sensitive element to the surface of the liquid in the tank. In scale it will determine the distance from the place of shipment pulse generator output) to the surface of the liquid.

The second reflected pulse U determines the time t passes impul which then determines the distance from the generator to the boundary line. The parameter t determines the propagation time of a pulse from the liquid surface to the border of the separation media. In this scale indicates the distance from the liquid surface to the border of the separation media.

The computing unit 6 pulses UoU1U2,..., Un(where N is a number and serial number of sections environments starting from the separation of the air-liquid) calculates all parameters storage of liquids: volume, height, number of layers section. The upper level of each of the immiscible liquids is determined by the formula

hi= 1/2v(t) - tiwhere i = 1...N, and its volume according to the formula

vi= F(hi; h) , where F is the calibration function.

The total volume is defined as the sum

V=Vi, i=1...N ..

The proposed device the greatest effect can give when used in the storage, stationary and especially offline, where you can hit of extraneous fluids.

The error count is not more than 0.5%.

A DEVICE FOR DETERMINING the LIQUID LEVEL IN the TANK containing the sensing element made in the form of two isolated from other conductors connected to the generator output and the receiver input, the output of which is s, located at different levels and connected to the generator output and the receiver input, and serially connected analog-to-digital Converter and a computing unit that is connected to the input of the indicator, with the input of analog-to-digital Converter connected to the amplifier output, and the generator and the receiver is made of the pulse.


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