SU807144A1 - Device for device for determining liquid phase in gas flow - Google Patents

Description

The invention relates to control. technical processes and can be used to detect liquid droplets in a gas stream. A device is known for measuring the consistency of substances by their dielectric properties using an electric capacitive sensor, between the electrodes of which a controlled substance is located. The device is also used to detect moisture droplets in a gas stream passing through a measuring capacitor, since the dielectric constant of a gas increases when 15 droplets of liquid appear in it, which leads to an increase in the capacitance of the condenser [1].

However, the device does not have selectivity, since the capacitor 20 of the capacitor also increases with increasing dielectric constant of the gas even in the absence of liquid droplets. In addition, the sensitivity of the known device at large-75 chic gaps is low, which does not allow to control the appearance of small drops in the gas stream.

It is also known a device containing a measuring capacitor with 30 controlled product, included in one of the arms of the transformer bridge, to the output of which a recording device is connected. The device has high sensitivity at large gaps of the measuring capacitor, since when connecting the product to a common point of the measuring circuit, most of the electric current is shorted to the controlled product and the capacitance of the measuring capacitor decreases.

The device can also be used to detect the liquid phase in the gas stream [2].

However, it is not possible to practically contact controlled liquid droplets with a common point in the measuring circuit. In addition, the use of any connecting conductor for the implementation of an electric claw of a liquid drop with a common point in the measuring circuit leads to a control error due to distortion of the electric field of the measuring capacitor. There is also an error from the measurement of the contact resistance of the drop with a common point on the circuit.

The purpose of the invention is to increase the accuracy of control and sensitivity.

This goal is achieved by the fact that the device further comprises a current adder and a negative signal selector, and the measuring capacitor is made in the form of two pairs of electrodes arranged in series and coaxially, of which two high potential are connected to the opposite shoulders of the transformer measuring bridge, and two low potential are connected to the adder currents, the output of which is connected to the recording device through a negative signal selector.

In Fig., 1 shows a functional diagram of a device for detecting a liquid phase in a gas stream; in FIG. 2 diagram of the output signal about the adders of currents.

The device comprises a high-frequency generator 1, a measuring transformer 2, a measuring capacitor 3, a compensation capacitor 4, an adder 5 currents, a selector 6 _Z. negative signal recording device 7.,

When the gas stream passes through the measuring capacitor and in the absence of liquid droplets in the stream, the transformer measuring bridge formed by the measuring transformer 2, the measuring capacitor 3 and the compensation capacitor 4 is balanced at the input and, therefore, at the output of the selector there is no signal. The increase in the dielectric constant of the gas medium, as well as its increase relative to humidity, is compensated (0 by the capacity of the compensation capacitor 4.

With the passage of a drop of liquid through the measuring capacitor and the position of this drop between the electrodes, for example a and 6, an increase in the capacitance between these electrodes occurs. With further movement of the droplet toward the center of the capacitor, the capacitance between the electrodes a and ά decreases and reaches a minimum value when the droplet is stretched in the eon of electrical symmetry of the measuring capacitor. Moreover, the value of this capacitance is less than the initial value for us, since in the aeon of electrical symmetry the drop is at zero potential, while most of the lines of force are shorted to a drop of liquid. Further movement of 55 drops leads to a similar change in capacitance between electrodes C and a.

As a result of reducing the capacitance of each pair of electrodes, the signal at the output of the adder 5 currents decreases, which leads to a change in the polarity of the signal from the measuring bridge. In this case, the selector 6 generates a signal for the registrar 7.

Thus, the device has a high sensitivity and responds to the appearance of a liquid phase without the implementation of a special electrical connection of liquid droplets with a common point of the measuring circuit, which increases the accuracy of control.

High selectivity allows continuous monitoring of single droplets in the gas stream during the process. The absence of contact with the drops increases the reliability of measurements and allows to increase the service life of the device. The device can be used in a non-contact liquid phase detector in a gaseous medium, as well as in a detector of metal particles in liquid fuel.

Claims (2)

.one . The invention relates to the control of technical processes and can be used to detect liquid droplets in a gas stream. A device is known for measuring the consistency of substances by their dielectric properties using an electric capacitive sensor, between whose electrodes a controlled substance is located. The device is also used to detect water droplets in the ke gas passing through the measuring capacitor, since the dielectric constant of a gas increases when liquid drops appear in it, which leads to an increase in the capacitance of capacitor 1. However, the device is not selective. the capacitance of the capacitor also increases with an increase in the dielectric constant of gas dsche in the absence of liquid droplets. In addition, the sensitivity of the known device at large gaps is low, which makes it impossible to control the appearance of small droplets in the gas stream. It is also known a device containing a measuring capacitor with: a monitored product, included in one of the arms of a transformer bridge, to the output of which a recording device is connected. The device has a high sensitivity with large gaps in the measuring capacitor, because when the product is connected to the common point of the measuring circuit, most of the electrical flow is shorted to the product being monitored and the capacitance of the measuring capacitor decreases. The device can also be used to detect the liquid phase in the gas stream. However, it is practically impossible to make contact between the controlled liquid kg of the shot and the common point of the measuring circuit. In addition, the use of any connecting conductor for carrying out the electric clock of a liquid drop with a common measuring point leads to an error of control due to the distortion of the electric field of the measuring capacitor. There is also an error in measuring the resistance of the contact of a drop with a common point of the circuit. The purpose of the invention is to improve the accuracy of control and sensitivity. The goal is achieved by the fact that the device additionally contains a current adder and a negative signal selector, and the i-switch kondeps & is made in the form of two pairs of electrolytes arranged in series and coaxially, and two high-potential connected to the transformer measuring bridge, and two low-technology - to the current adder, the output of which is connected to the registering pysaaej device through the selector of the external signal. Fig. 1 shows a functional diagram of a device for detecting a liquid phase in a gas stream; in fig. 2 is a diagram of the output signal of current accumulators. The device contains a high-frequency generator 1, a measuring transformer 2, a measuring capacitor 3, a compensating capacitor 4 an adder 5 currents, a selector b / a negative signal, a recording device 7 ,, when a gas stream passes through the measuring capacitor and the absence of liquid droplets in the stream , the transformer measuring bridge formed by the measuring transformer 2, the measuring capacitor 3 and the compensating capacitor 4 is also balanced at the input and, therefore, at the output of the selector There is no signal. The increase in the dielectric constant of the gas medium, as well as its increase relative to humidity, is compensated by the capacitance of the compensation capacitor 4. When a liquid drop passes through the measuring capacitor and the location of this drop between the electrodes, for example, a and 6, the capacitance between these electrodes increases. Upon further movement of the droplet to the center of the capacitor, the capacitance between the electrodes (L and S decreases and reaches the minimum value when the droplet compresses in the zone of electrical symmetry of the measuring capacitor. Moreover, the value of this capacitance is much smaller than the original value, since under a zero potential, while most of the lines of force are short-circuited to a drop of liquid. Further movement of the drop leads to a similar change in the capacitance between the electrodes C and a. In order to reduce the capacitance of each electrode bet, the signal at the output of the current adder 5 decreases, leading to a change in the polarity of the signal from the measuring bridge. At the same time, the selector b outputs the signal for the recorder 7. Thus, the device has an increased sensitivity and responds to liquid phase without making special electrical connection of liquid droplets to a common point of the measuring circuit, which keeps the accuracy of control. The high selectivity allows continuous monitoring of single droplets in the gas stream during the process. The absence of contact with the droplets increases the reliability of the measurements and increases the service life of the device. The device can be used in a contactless signaling device of the liquid phase in a gaseous medium, as well as in a signaling device of metal particles in a liquid fuel. Claims An apparatus for detecting a liquid phase in a gas stream, comprising a measuring capacitor included in a transformer measuring bridge, and a recording device connected to the output of the measuring bridge, so that, in order to increase accuracy and sensitivity detection, it additionally contains the accumulator TRK and the negative signal selector and the measuring capacitor is made in the form of two pairs of electrodes arranged in series and coaxially, in which two high-potential connected to the opposite shoulders of the measuring transformer PCM one but two low-potential - currents to the adder, whose output is connected to the device via the selector registrirukvdemu negative signal. Sources of information taken into account in the examination V 1. USSR author's certificate number 167067, cl. G 01 N 27/22, 1962. 2. USSR author's certificate number 346569, cl. G 01 N 7/08, 1970 (prototype). MimrythemnO „Aa. ,, .-:. , ; . -about .l.- with (