SU1730540A1 - Indicator of electroconductive fluid level - Google Patents

Abstract

The invention relates to a measurement technique, in particular, to devices for determining the level of an electrically conductive medium. The purpose of the invention is to improve the accuracy of the level indication in the presence of a transition region with a two-phase state of an electrically conductive medium. The generator 13 generates an alternating voltage on the electrodes of the sensors 7, and the current flowing when the electrodes are immersed in the medium between them passes through the current-voltage converter 8, stands aside from interference in the filter 9 and is compared with a constant signal in the discriminator 10. Yes-no to the indicator element. At the same time, the signal from sensors 7 is corrected depending on the value of the specific conductivity of the medium by the automatic signal control unit 12. 4 il. 6 .Z .. s about 01 "N About Fig.Z

Description

The invention relates to a measurement technique, in particular, to devices for monitoring parameters in heat exchange and separation devices, in which there are two phases of the medium: liquid and vapor.

The problem is in fixing the level of the transition phase, the so-called. swollen environment layer with variable conductivity.

A device for indicating such a level is known, comprising samplers installed at a predetermined height in the steam generator PGV-1000, a system for pumping sodium nitrate into the steam generator, a sampling system and a device for analyzing samples, such as a photometer flame.

Also known is a level indicator of an electrically conductive medium, selected as a protype of the proposed device, which includes conductometric sensors located along the rod and connected to a power source and corresponding measuring channels with an indicator element, each sensor being made in the form of two flat parallel electrodes.

The disadvantages of this device include: the possibility of false triggering during level pulsations and conductivity in the transient region of the medium; the horizontal arrangement of the planes of the electrodes, which does not provide the necessary time for analyzing the electrical conductivity of the medium; the absence of a grounded electrode between the measuring electrodes, which can lead, due to the formation of deposits between them, to the presence of leakage currents, which reduce the accuracy of the device.

The purpose of the invention is to improve the accuracy in the presence of a transition region with a two-phase state of an electrically conductive medium.

To this end, in the level indicator of an electrically conductive medium, including conductometric sensors located along the rod and connected to a power source and corresponding measuring channels with an indicator element, each of the sensors is made in the form of two flat parallel electrodes whose planes are arranged vertically, each measuring channel is made in the form of series-connected current-voltage converter, filter and discriminator, and, with the exception of the upper sensor channel, is connected to the unit automatic control of the signal whose input is connected to the output of the filter, and

output-with the input of the converter of an upstream sensor adjacent to it, with the output of each automatic control unit of the lower sensor signal

also connected to the input of the converter of the same channel.

FIG. 1 shows conductometric sensors placed on the rod; in fig. 2 - conductometric sensor, longitudinal section; in fig. 3 is a block diagram of a level indicator; in fig. 4 - a possible variant of the flowchart.

The device consists of plate electrodes 2 placed on rods 1, arranged in a vertical plane and fixed in insulators 3, as well as grounded electrodes 4 installed between electrodes 2 outside the measuring zone of 4, current leads 5 are fixed on rax 1 rod.

The block diagram of the level indicator (Fig. 3) consists of measuring channels 6 connected to conductometric sensors 7, including electrodes 2 and 4, and

5 insulators 3. Measuring channel 6 contains current-voltage converter 8, filter 9, discriminator 10 and indicator element 11, which are connected to each other. All channels 6, with the exception of the top sensor 7 itself, are made with automatic control unit 12 signal (BARS), which are a series-connected peak detector, a source

5 a repeater and adjustable resistances, for example, field effect transistors, controlled at the input by the amplitude of the signal from the filter 9.

The output of block 12 is connected to the input of the pre-rammer 8 of the adjacent channel 6 of the upstream sensor 7. The input of the block 12 of the channel 6 of the lowest sensor 7 is also connected to the input of the converter 8 of the same channel (i.e. the lowest

5 sensor 7 is used as a control). All sensors 7 are powered from source 13.

FIG. 4 shows a variant of the block diagram of the device in which the input of the block 12 co0 is only connected with the output of the filter 9 of channel b of the lowest sensor 7, and the output with the inputs of converters 8 of all channels 6

The difference in the block diagrams (FIGS. 3 and 4) of co5 is that the circuit in FIG. 3 tracks the change in the density of a two-phase medium both in time and in the space of the monitored volume, and the block diagram in FIG. 4 - only the change in density over time.

The level indication in the monitored volume is carried out as follows.

One of the electrodes 2 of the sensor 7 is supplied with alternating voltage from the power source 13.

When the transient phase of the medium reaches the level at which the electrical circuit between electrodes 2 closes, the current from the corresponding sensor 7 enters the converter 8. Filter 9 extracts the useful signal and discriminator 10 compares it with the specified discrimination signal. When the signal from filter 9 exceeds the value of a constant discrimination signal, unit 10 outputs a calibrated signal of the form “No” to indicator element 11, which records the presence of the level of the transition phase of an electrically conductive medium strictly from the middle of the measuring zone of sensor 7, i.e. in the middle of the vertical plates 2.

The signal of the converter 8 is corrected depending on the value of the specific conductivity of the liquid phase of the medium using block 12 and. thus, it automatically takes into account its change both in height of the monitored volume and in time.

Characteristics of BARS 12 and the parameters of the discriminative signal in block 10

They calculate on the basis of the conditions of the maximum possible conductivity values of the controlled two-phase medium.

Claims (1)

The invention The level indicator of an electrically conductive medium, including conductometric sensors located along the length of the rod, each of which is made in the form of two flat parallel electrodes and connected to a power source and measuring channel with an indicator element, characterized in x the presence of a transition region with a two-phase state of an electrically conductive medium; the planes of the electrodes of each sensor are arranged vertically; each measuring channel is made in the form of a sequence connected to the current-voltage converter, filter and discriminator and, with the exception of the upper sensor channel, is connected to the automatic control unit of the signal, the input of which is connected to the filter output, and the output to the input of the current-voltage converter adjacent to the upstream sensor; the output of each automatic signal control unit is connected to the converter input of the same channel. 1 FIG. 2 JUNE 0 Fig.b