SU1589184A1 - Apparatus for measuring moisture content of steam-liquid flows - Google Patents

Abstract

The invention relates to the field of measurement technology and can be used to measure the humidity of vapor-liquid flows in installations that generate and use steam. The purpose of the invention is to improve the measurement accuracy. A device for measuring the humidity of vapor-liquid flows contains equal capacitance dielectric constant and flow pressure sensors, equipped with an electrical input connected to the internal electrodes of the sensors and through capacitance meters with a comparison circuit, both of which are made in a common cylindrical case, which is an external electrode, the second capacitive sensor has in the housing channels for the measured flow, connected with the working volume of the first sensor, the channel connecting the working volume of the second sensor with the flow Still at the bottom of the sensor, the output of the flow from the channels of the body of the second sensor and the input of the flow in the first sensor are located in close proximity to electrical inputs. 1 hp f-ly, 1 ill.

Description

As an electrical conductor, you can: apply a ceramic with a conductor embedded in it; -to the output 7 of the sensor of the under-I keys, the input of the first coaxial cable: 8, the latter is used to connect the output 7 of the electric sensor with the main high-frequency meter 9 of the capacitance As the first coaxial cable 8., for example, a coaxial cable of the type PK-75 can be used,

The main high-frequency capacitance meter 9 is designed to obtain an electrical signal in magnitude; the electrical capacitance of the sensor 1 of the vapor-liquid mixture; As a measure; l can be used, for example, an E 7-12 type meter, To the input from: a meter 9 an output is connected the first KO axial cable 8, and its output is connected to the first input of the comparison element 10.

An electric flow pressure sensor 1I serves to receive a signal in the form of an electrical capacitance only depending on the pressure of the flow at a constant, unchanged degree of humidity of the medium in the sensor, close to zero. The sensor is a new design. It consists of a housing 12, (the sensor is a continuation of the housing 2 of the electric sensor 1, the external electrode 13 is coaxially mounted in the housing 12, the extension of the electrode 3 of the sensor 1 is extended, the central electrode 15 is introduced through the lower turn of the housing 12; 13 in the upper end is hermetically sealed with housing 16. To communicate the interelectrode space of sensor 1 with a gap established by the external electrode 13 and housing 12, windows 17 are made in the lower part of the external electrode 3, Electric pressure sensor 11 sweat The eye is also provided with an output L 8 of the sensor and an outlet nozzle 19, against which a hole 20 is located below the lower section of the external electrode 13,

In the device, it is necessary to observe the equal dimensions of the useful capacitances of the electric sensor 1 of the vapor-liquid flow and the electric sensor 11 of the flow pressure, which can be achieved by analogy with the geometric dimensions of the sensors 1 and 11,

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The electrical inputs 4 and 14 are similar in design 1И, and the own capacitances of both are the same in a wide range of temperature and pressure measurements,

The output 18 is connected to the input of the second coax (a1 cable 21, designed to connect the output 18 with a high-frequency compensation meter 22, the second coaxial cable 21 requires the use of a cable whose own capacitance and performance characteristics are adequate to those of the first coaxial cable 8 ,

The compensation high-frequency capacitance meter 22 serves to obtain an electrical signal according to the electrical capacitance of the sensor 11. A second coaxial cable 21 is connected to the input of the compensation and high-frequency capacitance meter 22 by the output, and the output of the meter 22 is connected to the second input of the reference element 10,

Comparison element 10 is used to obtain in analog form the difference between the signals of the main and commutation high-frequency meters 9 and 22. The outputs of the main and compensation meters 9 and 22 are connected to two inputs of the element 10, and the outputs of the comparison element 10 are connected to the inputs of the analog-digital converter 23. The latter is designed to automatically convert a similar signal to its input, c. the output of the comparison element 10, and the output of signals to the input and code buses of the display unit 24. The input of the analog-digital converter 23 is connected to the output of the reference element 10, and to the outputs thereof. connected display unit 24.

The display unit 24 serves to visually display information to the operator in decimal code. As the display unit 24, for example, serially-release & vbtA PIU-2 unit can be used. The code bus of the driver is connected to the code outputs of the analog-digital converter 23,

The basis for constructing a device for measuring the humidity of vapor-liquid flows is based on the principle of compensation mainly: an important factor, depending on the humidity and pressure of the vapor-liquid type.

current constituting pressure stream.

In this case, the signal for the humidity of the vapor-liquid flow is determined by the expression

(y) (y, p) - e (p).

 (y) is the signal of the magnitude of the moisture of the vapor-liquid flow; , (y, P) - signal by the magnitude of humidity and pressure of the vapor-liquid flow;

(P) - signal by the pressure value of the vapor-liquid flow. The device operates as follows.

The vapor-liquid flow under study enters through the inlet pipe 6 into the interelectrode space of the electric sensor 1 of the vapor-liquid mixture formed by the central electrode 5 and the external electrode 3. Then the flow, striking the housing 16, is directed through the windows 17 into the gap of the electric sensor 11, which consists From the external electrode 13 and the housing 12, Moving along this gap, the flow heats the external electrode 13 and in the working space of the electrical sensor 11 of the pressure of the flow consisting of the central electrode 15 and the external electr sort 13 is set environment whose temperature is practically equal to the temperature of the medium investigated. Upon further movement of the vapor-liquid flow directly ONbiBaeT electrical input 14, thereby equalizing the temperature of the electrical input and the vapor-liquid flow. A distinctive feature of this design is direct washing. We examine the 1m flow of the electrical input 4 and practically without delay the same flow of the electrical input 14, which ensures a simultaneous change in the temperature state of the electrical input 4 and .14.

In the lower section of the outer electrode 13, the vapor-liquid flow under study washes the electrical input 14 and the lower part of the outer electrode 13 and through the outlet 19 is removed from the device. Since the flow at the output of the sensor 1 1 has only one direction, namely, the pipe 19, the existence of the hole 20 in the external electrode 13 located against the pipe 19 provides a suction effect. Thus, Sun Condensiro

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The bath or fluid located in the interelectrode space of sensor 11 under the action of hydrostatic and gravitational forces is separated into the lower part of the external electrode 13 and removed through the opening 20 into the stream. For this reason, in this space there is only the vapor phase of the vapor-liquid flow without inclusions of liquid. At the same time, since the interelectrode space of the sensor 11, formed by the central electrode 15 and the external electrode 13, communicates with the test by the 1m flow, through the hole 20, there is a medium with a pressure almost equal to the pressure of the flow under study

As a result, in the interelectrode space of the sensor 1 of the vapor-liquid mixture, we study the liquid-vapor flow and the capacitance of this sensor depends on the humidity and the pressure of the flow, and exists in the interelectrode space of the pressure sensor I1. the first phase without blotches of liquid, i.e. with a constant degree of humidity, but at a pressure equal to the pressure of the test stream. When the pressure of the vapor flow under study changes, the electrical capacitances of sensors 1-11 11 change accordingly by the same values (with a constant degree of moisture content of the flow), as well as the electrical characteristics of electrical inputs 4 and 14 synchronously change due to temperature changes.

The capacitance of the electrical sensor I of the vapor-liquid mixture is measured via output 7 with an electrical wiring connected — the first coaxial cable 8 of the main high-frequency capacitance meter 9 of the capacitor. This value corresponds to the output signal of the meter 9, I

The capacitance of the electric flow pressure sensor 11 is measured through the output 18 with the electrical input 14 connected, and the second coaxial cable 21 with a high-frequency compensation capacitance meter 22. This value corresponds to the signal at the output of the meter 22,

The input of the comparison element 10 receives signals from the main and compensation meters 9 and 22, respectively. At the output of the comparison element 10, a signal is output, which depends on only the degree of humidity of the test flow, i.e. the influence of the vapor-pressure flow pressure, changes in the capacities of the communication lines caused by external conditions, are automatically compensated. Then, an electrical signal, indicating the moisture content of the flow under study, is fed through the analog-digital converter 23 to the display unit 24, which displays this information to the operator in a de- ficient code. Toy.work analog-digital converter ..,

Claims (2)

Claims; 1. A device for measuring the humidity of vapor-liquid streams, containing two capacitance meters, a device for the flow of water, a flow sensor with an electrical input, a second identical electrical input, each electrical input connected 25 with a capacitance meter, which differs from it in order to improve the measurement accuracy, it contains an additional closed capacitive sensor that has a connection channel with the flow, the second electrical input is installed in an additional sensor, and the capacitances of both sensors are the same. 2. The device according to claim I, about tl and - the fact that both sensors are made in a common cylindrical body, which is an external electrode, and the additional capacitive sensor has channels in the case for the measured flow, connected to the displacement of the first sensor, The channel for connecting the working volume of the second sensor to the flow is located in the lower part of the sensor, the output of the flow from the channels of the body of the additional sensor and the input of the flow to the first sensor are placed in close proximity to the electrical inputs.