RU2805766C1 - Method for measuring level of liquid and granular media in tanks - Google Patents

Abstract

FIELD: measurement.

SUBSTANCE: methods for measuring the level of liquid and granular media in tanks and signaling when they are filled. In this case, metal printed tracks are used as capacitors of discrete capacitive level gauges, mounted on a printed circuit board in the form of two vertical lines, and their exciting plates are arranged sequentially one after another in the first line and connected to the clock pulse generator through the first capacitor switching matrix, and the receiving plates of capacitors are placed in series in the second line opposite the exciting ones, while each of the n receiving plates is connected to the corresponding key of the second matrix for switching and scanning capacitors, the common output of the matrix is connected to an analog-to-digital converter with a highly stable power supply, and the analog-to-digital converter is connected to the control unit.

EFFECT: increasing the accuracy of measurements, reducing labor and time costs, as well as providing the ability to determine multilayer media of various types of liquid and granular bodies. In the proposed method, discrete capacitive level meters containing a control unit, a clock pulse generator, and level converters into electrical signals are installed vertically one after another on the inner surface of the tank.

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Description

The invention relates to measurement methods, in particular to methods for measuring the level of liquid and granular media in tanks and alerting them when they are filled [G01F 23/00, G01F23/28].

From the prior art there is known a METHOD FOR MEASURING THE LEVEL OF A DIELECTRIC LIQUID [RU 2407993 C1, publ.: December 27, 2010], characterized by the fact that when it is implemented, the capacitance of a two-electrode capacitor liquid level sensor is measured alternately in any sequence and the capacitance of the same sensor is measured after connecting a capacitor dielectric properties sensor is connected to it, after which the level from the upper end of the two-electrode capacitor liquid level sensor is calculated using the appropriate formula.

The disadvantages of the known method are low accuracy, expressed in the inability to compensate for measurement errors caused by changes in the dielectric constant of the controlled liquid, and the dielectric constant can also change in cases of changing the brand or type of the controlled liquid and when its temperature changes.

From the prior art, there is known a METHOD FOR MEASURING THE LEVEL OF A DIELECTRIC LIQUID [RU 2242727 C2, published: 12/20/2004], adopted as a prototype, characterized by the fact that when it is implemented, capacitive level gauges are initially immersed in it in the form of a series of numbered ones located one above the other in ascending order from bottom to top, identical individual capacitors are installed, while dielectric liquid freely flows into the interelectrode space. Then the capacitances of individual capacitors are measured sequentially, starting from the bottom, and based on the results of the measurements, the desired serial number of the first of the individual capacitors, in which the interelectrode space is filled with a dielectric liquid less than its length, is determined. After that, the total capacitance of a single capacitor with the desired serial number and the lower single capacitor connected to it in parallel for the duration of the measurement are measured. Then the length of filling the interelectrode space with the dielectric liquid of these two parallel-connected single capacitors is determined using the appropriate formula, and the level of the dielectric liquid is determined using the appropriate formula.

The main technical problems of the prototype are:

significant labor and time costs in the process of measuring the level of a dielectric liquid, expressed in the need to carry out a large number of operations for measuring the capacitances of individual capacitors, as well as in the process of servicing capacitors, expressed in the difficulty of removing the product adhering between the electrodes of all capacitors;

insufficient accuracy of measurements, expressed in the inability to compensate for their error caused by changes in the dielectric constant of the controlled liquid, as well as a high degree of adhesion of products to the electrodes of the capacitor;

the inability to implement this method in determining multilayer media of different types of liquid and granular bodies and the inability to separate them.

The objective of the invention is to eliminate the shortcomings of the prototype.

The technical result of the invention is to provide the possibility of creating a method for measuring the level of liquid and granular media in tanks using discrete capacitive level gauges, reducing labor and time costs when measuring the level and servicing capacitors of level gauges, increasing the accuracy of measurements, and also providing the ability to determine multilayer media of different types of liquid and loose bodies.

The specified technical result is achieved due to the fact that when implementing the proposed method for measuring the level of liquid and granular media, discrete capacitive level meters containing a control unit, a clock pulse generator, and level converters are installed vertically one after another on the inner surface of the tank to the depth required for measurement. electrical signals, while metal printed tracks are used as capacitors of discrete capacitive level gauges, mounted on a printed circuit board in the form of two vertical lines, separated by an air gap and located in the same plane, and their exciting plates are arranged sequentially one after another in the first line and connected to a clock pulse generator through the first capacitor switching matrix having n outputs, and the receiving capacitor plates are placed sequentially in the second line opposite the exciting ones, with each of the n receiving plates connected to the corresponding key of the second capacitor switching and scanning matrix having n inputs, the general output of the matrix is connected to an analog-to-digital converter with a highly stable power supply, and the analog-to-digital converter is connected to a control unit containing a calibration unit with logic, a calibration random access memory, control and data registers, a serial interface with control logic, a general purpose I/O port, and microcontroller, united by a common digital bus, and the input of the digital signal transceiver is connected to the output of the microcontroller.

In a particular case, the output of the digital signal transceiver is connected to an additional signaling unit, designed to analyze the level of quanta of the analog-to-digital converter from each capacitor, determine the composition of the mixture layers filling the tank, and also signal about its filling.

In a particular case, lines of capacitors are installed to ensure that the outermost capacitors overlap.

In a particular case, each discrete capacitive level gauge is connected to an additional signaling unit via a digital communication line.

In a particular case, a clock generator, a switching and capacitor scanning matrix, an analog-to-digital converter, and components of the control unit are mounted on one integrated circuit with the ability to provide excitation of sensors with alternating current, data collection, compensation for changes in environmental conditions, detection of changes in capacitance, and also generating an output signal.

In a particular case, the additional alarm unit includes a microcontroller, an spark protection barrier, two data transfer interfaces, three relay outputs with the ability to detect water, oil and device malfunction, volatile memory for storing event logs, a discrete input, a button for switching to self-diagnosis, LEDs to indicate the operation of the device, while one of the data transfer interfaces is designed to connect to level meters, the second - to the automation system.

Brief description of the drawings.

In fig. 1 shows a diagram of the implementation of a method for measuring the level of liquid and granular media in a tank;

In fig. Figure 2 shows a block diagram of devices used to implement a method for measuring the level of liquid and granular media in a tank;

In fig. Figure 3 shows a three-dimensional view of the sequential placement of four level meters with an alarm unit in the tank.

The figures indicate:

1 - installation of discrete capacitive level gauges on the inner surface of the tank; 2 - installation of an alarm unit; 3 - connection of discrete capacitive level meters with an alarm unit; 4 - power supply to the alarm unit and discrete capacitive level gauges; 5 - control of the level of liquid and granular bodies in the tank in automatic mode; 6 - discrete capacitive level gauge; 7 - clock generator; 8 - line of exciting capacitor plates; 9 - line of receiving capacitor plates; 10 - air gap; 11 - first capacitor switching matrix; 12 - second matrix for switching and scanning capacitors; 13 - analog-to-digital converter; 14 - highly stable power supply; 15 - signal calibration unit with logic; 16 - calibration random access memory; 17 - control and data registers; 18 - serial interface with control logic; 19 - general purpose I/O port; 20 - microcontroller; 21 - digital signal transceiver; 22 - reservoir; 23 - alarm block.

The claimed method for measuring the level of liquid and granular media in tanks is carried out as follows.

The process of implementing the claimed invention (see Fig. 1) consists of installing discrete capacitive level meters on the inner surface of the tank 1, installing an alarm unit 2, connecting discrete capacitive level meters with an alarm unit 3, supplying power to the alarm unit and discrete capacitive level meters 4 and level control liquid and granular media in the tank in automatic mode 5.

When installing discrete capacitive level meters 6 (see Fig. 2, 3), containing a control unit, a clock pulse generator 7 (see Fig. 2), level converters into electrical signals in the form of capacitors, use level meters of a design in which their capacitors made in the form of metal printed tracks mounted on a printed circuit board in the form of a line of exciting plates of capacitors 8 and a line of receiving plates of capacitors 9, separated by an air gap 10 and located in the same plane, while the exciting plates of capacitors 8 are located sequentially one after another in the first line and connected to the clock pulse generator 7 through the first switching matrix of capacitors 11, which has n outputs, and the receiving plates of the capacitors 9 are located in series in the second line opposite the exciting ones 8, while each of the n receiving plates 9 is connected to the corresponding key of the second matrix of switching and scanning capacitors 12 , having n inputs, the common output of the matrix is connected to an analog-to-digital converter 13 with a highly stable power supply 14, and the analog-to-digital converter 13 is connected to a control unit containing a signal calibration unit with logic 15, a calibration random access memory 16, control and data registers 17, a serial interface with control logic 18, a general-purpose I/O port 19 and a microcontroller 20, united by a common digital bus, with a digital signal transceiver 21 connected to the output of the microcontroller 20, a clock pulse generator 7, a switching and scanning matrix of capacitors 12, Having n inputs, an analog-to-digital converter 13, the components of the control unit are mounted on a single integrated circuit, designed to provide excitation of sensors with alternating current, data collection, compensation for changes in environmental conditions, detection of changes in capacitance, and generation of an output signal.

Discrete capacitive level gauges 6 are installed at the depth required for measurement, with sequential placement one after another, while ensuring that the outermost capacitors overlap.

After that, an alarm unit 23 is installed on the upper part of the tank 22 in a place free from flooding, coaxially with the location of discrete capacitive level gauges 6, containing a microcontroller, a spark protection barrier, two data transfer interfaces, three relay outputs with the ability to detect water, oil and device malfunction, volatile memory for storing event logs, a discrete input, a button for switching to self-diagnosis mode, LEDs for indicating the operation of the device, while one of the data transfer interfaces is designed to connect to level meters, the second - to the automation system.

Then, each discrete capacitive level gauge 6, using a digital communication line, is connected to a signaling unit 23, made with the ability to analyze the level of quanta of the analog-to-digital converter 13 from each capacitor, determine the composition of the mixture layers filling the tank, and also signal about its filling.

After that, power is supplied to the alarm unit 23 and discrete capacitive level gauges 6, then the filling level of the reservoir 22 with liquid or granular bodies is monitored in automatic mode.

Between the exciting 8 and receiving 9 tracks of the lines of capacitor plates there is an electromagnetic field, the magnitude of which is determined by the capacitance of the capacitor, depending on the dielectric constant of the substance located between the capacitor plates, for example, air, liquid or granular body. As a result of filling the gap 10 between the capacitor plates with a substance, the sensor capacitance changes by an amount on the order of femtofarads, and this change is detected by a sixteen-bit analog-to-digital converter 13, powered by a highly stable power source 14. Next, the signals are supplied to the signal calibration unit 15 and calibration RAM 16.

The microcontroller 20 reads the code through the serial interface 18, the control logic of which, together with the calibration unit with logic 15 and the operational memory of calibration 16, automatically implements an algorithm for compensating for changes in environmental conditions.

Temperature, humidity and other factors affect the capacitance of sensors. Without user intervention, the device continuously calibrates to compensate for these factors, thereby reducing possible errors and preventing failures. The calibration sequence is performed automatically and at continuous intervals when the capacitor sensors are not touched by liquid or solids. The digital signal transceiver 21, connected to the output of the microcontroller 20, transmits the measurement results via a long line to the signaling unit 23.

The alarm unit 23 receives measured values from discrete capacitive level gauges 6, and then compares them with the boundaries characterizing air, water and oil/petroleum products, determined empirically and differing at different levels due to the design features of the control units. When liquids are detected, the corresponding relay outputs are activated, the LED indication on the alarm unit 23 changes, and an entry is made in the event log. In this way, flooding with water, melt water, oil or petroleum products is detected, the depth of flooding and the type of media flooding wells are determined.

Thus, the technical result consists in providing the possibility of creating a method for measuring the level of liquid and granular media in tanks using discrete capacitive level gauges, reducing labor and time costs when measuring the level and servicing capacitors of level gauges, increasing the accuracy of measurements, and also providing the ability to determine multilayer media different types of liquid and granular bodies, is achieved due to the fact that thanks to the use of the claimed method, it is possible to eliminate the sticking of a liquid or granular product on the plates, especially inside the capacitor due to the lack of a closed volume; in addition, their flat design makes it easy to ensure good insulation of the plates capacitors from the environment and quick cleaning of the device from accidental contamination, and there is also the possibility of detecting tank flooding with water, melt water, oil or petroleum products with determining the depth of flooding and the type of media flooding the tank, the composition of their layers with the possibility of signaling when the tank is filled.

Claims (6)

1. A method for measuring the level of liquid and granular bodies in a tank, characterized by the fact that when it is carried out on the inner surface of the tank to the depth required for measurement, discrete capacitive level meters are installed vertically one after another, containing a control unit, a clock pulse generator, and level converters in electrical signals, while metal printed tracks are used as capacitors of discrete capacitive level gauges, mounted on a printed circuit board in the form of two vertical lines, separated by an air gap and located in the same plane, and their exciting plates are arranged sequentially one after another in the first line and connected to a clock pulse generator through the first capacitor switching matrix having n outputs, and the receiving capacitor plates are placed sequentially in the second line opposite the exciting ones, with each of the n receiving plates connected to the corresponding key of the second capacitor switching and scanning matrix having n inputs, the general output of the matrix is connected to an analog-to-digital converter with a highly stable power supply, and the analog-to-digital converter is connected to a control unit containing a calibration unit with logic, a calibration random access memory, control and data registers, a serial interface with control logic, a general purpose I/O port, and microcontroller, united by a common digital bus, and the input of the digital signal transceiver is connected to the output of the microcontroller. 2. The method according to claim 1, characterized in that the output of the digital signal transceiver is connected to an additional signaling unit, configured to analyze the level of quanta of the analog-to-digital converter from each capacitor, determine the composition of the mixture layers filling the tank, and also signal about its filling . 3. The method according to claim 1, characterized in that the lines of capacitors are installed in series one after another, ensuring that the outermost capacitors overlap. 4. The method according to claim 1, characterized in that each discrete capacitive level gauge is connected to an additional signaling unit via a digital communication line. 5. The method according to claim 1, characterized in that the clock pulse generator, capacitor switching and scanning matrix, analog-to-digital converter, and components of the control unit are mounted on one integrated circuit with the ability to provide excitation of sensors with alternating current, data collection, and compensation for changing conditions environment, detecting capacitance changes, and generating an output signal. 6. The method according to claim 2, characterized in that the additional alarm unit includes a microcontroller, an spark protection barrier, two data transfer interfaces, three relay outputs with the ability to detect water, oil and device malfunction, volatile memory for storing event logs, discrete input, a button for switching to self-diagnosis mode, LEDs for indicating the operation of the device, while one of the data transfer interfaces is designed to connect to level meters, the second - to the automation system.