SU913208A1 - Pickup for measuring actual volume vapor content in pipes - Google Patents

Description

The invention relates to measuring equipment and can be used to measure the true volumetric steam content in the pipes of industrial and research installations.

Known resistive sensor for measuring the average volume true. steam content, the principle of operation of which consists in the dependence of the electrical conductivity of a two-phase mixture on steam content, consisting of two ¹ thin metal rings inserted into the pipe at some distance from each other, the external diameter of which coincides with the internal diameter of the pipe II]. .

The disadvantage of the sensor is a large measurement error due to insufficient localization of measurement along the length of the pipe due to the large length of the sensor; Dependence of the sensor resistance on the uneven distribution of the vapor phase along the pipe radius.

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The closest in technical essence to the present invention is a sensor consisting of an external electrode, which is both a pipe wall and an internal rod electrode inserted into the center of a pipe using a L-shaped tube [2].

However, such a sensor, introducing perturbation into the flow, changes the structure of the flow, has a considerable length, which leads to the measurement of steam content not in a specific section of the pipe, but in a significant volume, and its resistance, and consequently, the measured value, may depend on the distribution of steam cross section.

In addition, the internal electrode creates a hydraulic resistance to flow, which, in turn, can cause additional vaporization and a change in steam content itself. All this leads to large measurement errors.

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The purpose of the invention is to improve the accuracy of measurements of true volumetric steam content.

This goal is achieved by the fact that in a known steam content sensor comprising a housing and two electrodes located in it, two dielectric cylinders are inserted into the housing coaxially without a gap, two cutouts for electrodes opposite each other are made in the inner cylinder, and the electrodes are made in the form of segment parts metal hollow cylinder, the diameter and thickness of which coincide with the diameter and thickness of the internal dielectric cylinder, and the segment parts are formed by cutting planes parallel to the axis etallicheskogo cylinder and spaced from one another in the region of 0.6-0.8 inner radius of the dielectric cylinder and the electrode length is 1-1.5 radius of this cylinder.

This arrangement of the electrodes allows to obtain a uniform electric field with a small length (1-1.5 of the inner diameter of the pipe), since in this case the curvature of the electric field at the ends of the electrodes does not have a noticeable effect on the measurement accuracy. In addition, the cutting plane for each electrode is removed by 0.6-0.8 of the internal diameter of the pipe or, in other words, the arc occupied by each electrode is 90 °, which allows to reduce the dependence of the sensor resistance on the distribution of steam over the pipe section. In the case of a larger arc, the electric field lines are concentrated near the pipe wall, and thus, this peripheral area is more sensitive to a pair. At a smaller arc size, the central region of the pipe has a higher sensitivity.

FIG. 1 shows the proposed sensor section; in fig. 2 - electrode.

The resistive sensor includes a housing Ί, internal 2 and external 3 inserts and two electrodes 4 each, ^ of the sealed output 5, spring compensator 6, cup 7 and adapter 8.

Spring compensator 6 is provided to prevent changes in the channel cross section due to the expansion of the flu ~

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roplast at elevated temperatures. ' The adapter 8 serves to connect the sensor to the pipe. All metal parts are made of stainless steel.

The device works as follows.

The sensor is connected to a pipe of a circuit filled with a vapor-liquid mixture, the resistance of the sensor DD is measured by an appropriate device and the installed steam ratio M ’is determined by the established dependence ID / CdM -0 =. £ (4).

The use of the proposed resistive sensor ensures that there is no disturbance introduced into the flow by the sensor and the distribution remains unchanged; a pair of section; low hydraulic resistance, the ability to measure the true volumetric steam content throughout its area (from H ~ 0 to H = 1) under bubble, slug and ring flow regimes; localization of measurement along the length of the pipe, which makes it possible to attribute the measured steam content directly to the controlled section of the pipe, the low inertia of the change in resistance of the sensor; reduced dependence of the sensor resistance on the uneven distribution of steam over the cross section.

The use of the invention allows for continuous measurements of steam content in pipes and to select the optimal modes of their operation.

Claims (1)

Claim A sensor for measuring the true volumetric steam content in pipes, comprising a housing and two electrodes located in it, which replicates with the fact that, in order to improve measurement accuracy, two dielectric cylinders are inserted into the housing coaxially without a gap, in the internal cylinder two cutouts for electrodes are one opposite the other, and electrodes are segmented parts of a metal hollow cylinder, the diameter and thickness of which coincide with the diameter and thickness of the internal dielectric cylinder, and the segmented hours These are formed by cutting planes parallel to the axis of the metal cylinder and rac913208 6 placed from one another at a distance of 0.6-0.8 of the radius of the internal dielectric cylinder, and the length of the electrodes is 1-1.5 of the radius of this cylinder.