DD289333A5 - METHOD AND ARRANGEMENT FOR MONITORING LEVELS OF HYDROSTATIC HEIGHT LEVEL MEASUREMENT - Google Patents

Abstract

The invention relates to a method and an arrangement for monitoring level vessels of the hydrostatic height measurement according to the Differenzdruckmeszverfahren. With the help of one or more conductivity probes and a temperature measuring point, the comparative column of the height measuring device is constantly monitored, thereby realizing a correction of the height value mesz value. The Leitmöglichigkeitsmeszsonde (s) comes here the task to determine deviations from the defined height of the comparative column or, when using multiple probes, to determine the error due to these deviations and the vapor content in the comparative column. The temperature measurement point in the comparative column shows deviations from the calibration temperature and thus from the calibration density in the comparative column. {Nuclear power plant; Pressure vessel; Height level measurement; Pegelgefaesze; Differential pressure measurement; Computer link}

Description

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Field of application of the invention

The invention relates to a method and an arrangement for monitoring level vessels, as used in hydrostatic level measurement according to the differential pressure method. In particular, for pressure vessels with two-phase mixtures (water / steam), in which it can come during operation to strong parameter fluctuations and compliance with a predetermined level in the container with high accuracy safety and availability relevant importance for the operation of the entire system has.

Characteristic of the known state of the art

The level vessels described below are used for level measurement according to the hydrostatic principle. The principle is based on the differential pressure measurement between the hydrostatic pressure of two liquid columns, one column serves as a reference column and the other is formed by the measured height in the container. This process is widely used in steam generators in nuclear power plants with pressurized water reactors. The proper operation of the steam generators in nuclear power plants with pressurized water reactors is of great importance for the economic and species-preserving operation of the nuclear power plant blocks as well as for the prevention and control of incidents. A safety and availability relevant measure on the steam generator is the ride height. Prerequisite for the hydrostatic level measurement in containers with water-vapor mixtures is a constant condensation in the level vessel, that is, boiling of the water in the container. In this case, an approximately constant height level of the reference column is held in the level vessel by the condensing vapor. The design is possible in two forms, as a one- and two-chamber level vessel.

To determine the mass level in the pressure vessel in practice, the display devices are calibrated to nominal operating parameters. If deviations or changes in rated operating parameters occur during the process, this will result in faulty displays of the measuring system. The following factors are to be considered when considering the error:

- Error due to density changes in the impulse lines, especially in the reference column due to vapor formation.

- Error due to the change in the reference level in the level vessel.

- Error due to parameter change compared to rated operating parameters.

- Error due to the vapor content in the pressure vessel.

There is no known technical method that makes it possible to detect the causes of faults described and to correct on-line the measurement error of the height measurement.

In DE 3541613 a method is described in which, in addition to the differential pressure measurement via a temperature measurement and a flow rate measurement, the ride height is to be concluded. Statements about the change in density in the reference column due to the formation of vapor or statements about the measurement error due to a reduction of the reference level are not possible.

There are in practice efforts to address by elaborate structural changes to the identified shortcomings of the hydrostatic ride height measurement, so far without radical success.

Object of the invention

The aim of the invention is to improve the conditions for economical and plant-friendly operation of the nuclear power plant blocks.

-2- 289 333 Explanation of the essence of the invention

It is the object to detect at any time the parameters of vapor content, density and temperature as well as the reference level In the comparison column in order to correct the indicated level of height according to possible parameter fluctuations in the pressure vessel, which could also influence the measuring system of the measuring system.

According to the invention, this is achieved by introducing a conductivity measuring probe in such a way that it is possible to determine deviations of the nominal height level in the reference column in a specific tolerance range with this probe and to determine the relevance of the displayed level value value via an evaluation unit , The tolerance range is determined by the error limit. It is also possible with this probe to detect any boiling phenomena in the reference column and the refilling time. The refill time corresponds to the time that the measuring system is not ready for use due to the loss of height in the reference column. By introducing a plurality of probes, it becomes possible to unambiguously determine the display error due to the deviation of the reference level in the reference column from the target level. It is also possible to determine the vapor content in the reference column and thus the change in density due to vapor formation.

In addition to this measuring point with conductivity probe, a temperature measurement in the comparison column allows accurate conclusions about the important for this level measurement density of the liquid.

A connected arithmetic unit detects and processes the information thus obtained on-line, so that it is possible at any time to correct the displayed altitude or prove the operational readiness of the system. In this way, the errors described above and frequently occurring in the hydrostatic level measurement can be largely eliminated.

AusfQhrungsbelsplel

The invention will be explained in more detail using an exemplary embodiment. It shows

Fig. 1: The measuring arrangement for height measurement on the basis of a differential pressure measurement using a two-chamber level vessel and the location of the measuring points for monitoring the reference column.

By comparing the hydrostatic pressure in the pressure vessel (1) with the by the position of the two-chamber level vessel (2) fixed hydrostatic pressure in the reference column (3), a differential pressure is determined. The respective height level can be over the equation

, H (9, - 9 ") Δρ

9i = (1 - <p) 9 '+ φ · 9 "

9, - Density in the reference column

h _m - mass level in the tank

H - reference level in the reference column

9 '- Density water at boiling parameters

9 "- Dense steam at boiling parameters

Δρ - measured differential pressure

φ - vapor content in the reference column

g - gravitational acceleration

determine. A precise determination of the height is only guaranteed if H complies with the specified value and 9, is bekanrt.

This monitoring of the height H in the reference column is taken over by a conductivity measuring probe (4). For this purpose, such a probe was introduced into the level vessel in such a way that the tip of the probe with filled comparison column exactly the interface water / Dampferfaßt or slightly immersed. The immersion depth of the probe depends on the permissible deviation of the height H to the standard height in the reference column. If the level in the reference column falls below the specified value, this is clearly detected with the aid of this probe. With the help of the temperature sensor (5), the density can be determined on-line constantly and taken into account in the calculation of the ride height. Via an amplifier (7), all information is fed to a computer (8) and with the appropriate software, the level indicator can be corrected for each operating condition.

Claims (3)

1. A method for monitoring level vessels of the hydrostatic ride height measurement, characterized in that the relevance of the indicated ride height can be estimated by detecting the deviation of the ride height in the reference column (3) from the normal altitude with the help of a probe and the current temperature of the reference liquid. 2. The method according to claim 1, characterized in that by introducing a plurality of probes (4) in the comparison column (3) the error of the height indicator due to the deviation of the reference level from the target level and the density change due to vapor formation can be determined and corrected and thus the accuracy of Measuring system is further increased in unsteady operations. 3. Arrangement for monitoring level vessels of the hydrostatic level measurement, characterized in that arranged in the level vessel at least one probe in the boundary layer water / steam and other probes for determining the vapor content, offset in the depth of the reference liquid, these and a arranged in the comparison liquid Temperature sensor (5) with a computer (8) communicate electronically.