Method and device for monitoring the fill level of a liquid in a liquid container

Abstract

A method for monitoring the fill level of a liquid (F) in a liquid container, in particular for monitoring the coolant fill level in a reactor pressure vessel (4) of a pressurized water reactor system, wherein a determination is made about the drop in the liquid level (10) below the installed height of a heated thermal element (HT) by way of the temperature difference (DT) measured between said heated thermal element (HT) and an unheated thermal element (UHT) associated therewith, both of said elements being disposed in the liquid container, said method comprising the especially reliable triggering of an alarm with a short response time while maintaining a low level of physical and controls engineering complexity when the liquid level to be monitored falls below a critical value. To this end, according to the invention the temporal progression of the temperature difference (DT) is continuously monitored for any significant increase, in particular sudden increase, within a time interval of pre-determined duration (Delta t) prior to the respective evaluation time (t0), wherein an alarm signal is issued as soon as the change (Delta DT) in the temperature difference (DT) within said time interval reaches or exceeds a pre-determined limit value.

Description

Technical field [0001] The present invention involves a solution to monitor liquid levels in liquid containers in liquid containers, especially the liquid level of the coolant in the reactor pressure container used to monitor the reactor facilities of the water pressure reactor.The temperature difference between the unheated thermocouple associated with it is to determine whether the liquid surface has dropped to the installation position below the heated thermocouple, and both thermocouples are installed in the liquid container.In addition, the present invention also involves an electronic evaluation and control unit for implementing this method, as well as a device that configures and control the control unit to monitor liquid levels. Background technique [0002] In the measuring device or liquid level probe, the height of the liquid level in a liquid container can be inferred according to the thermal voltage generated by a heated thermocouple. The measurement device or liqui...

AI Technical Summary

Problems solved by technology

[0017] In addition to these obvious advantages, the method for regulating the heating current also has some disadvantages:

[0020] There are other problems besides this: if part of the heating wire is passed around by a medium that is colder than it, then this will cause a reduction in the heating current, resulting in a reduced temperature difference between the heated and unheated thermocouples, and lower signal amplitudes

This leads to a very laborious coordination of the interface between the measuring probe and the evaluation electronics

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