LU81800A1 - IMPROVEMENTS IN LEVEL DETECTION DEVICES AND METHODS - Google Patents

Description

9 i t% · »JL Claim for the priority of an Lp * patent application filed in Belgium J ~~ on 20.10.1978 under No 871.438 Ί 4 / C 1912/7810.

PATENT

METALLURGICAL RESEARCH CENTER -CENTRUM VOOR RESEARCH IN DE METALLURGIE,

Nonprofit organization -

Vereniging zonder winstoogmerk, in Brussels, (Belgium).

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Improvements to level detection devices and methods.

The present invention relates to improvements to a device for detecting the level of a liquid bath in a container, in particular a bath of molten steel in an intermediate basket for continuous casting.

In a previous application, a method for detecting the level of a liquid bath in a container has been proposed based on the measurement of the Archimedes' thrust at which. - - ~~ - - »- ~ - - -! 2 ί, 4 cise, we measure according to this previous process, the Archimedes thrust exerted on a stopper a steel bath contained in an intermediate basket of continuous casting and in which the said stopper rod is immersed. This measurement makes it possible, by an adequate regulation loop, to modulate the rate of casting of the steel so as to maintain in the basket a substantially constant level of metal.

The object of the present invention is to provide an appropriate sensor making it possible to continuously detect the buoyancy of Archimedes.subie by the submerged body and consequently the level of the liquid in the container.

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Another object of the invention is to provide a level detection device whose response time is very short and makes it possible to follow, almost instantaneously, any variation in said level.

The device for detecting the level of a liquid in a container, object of the present invention, which comprises a rod immersed in said liquid connected by an arm to a support integral with said container, and a sensor for measuring the thrust d 'Archimedes undergone by the said bar, is essentially characterized in that the said sensor consists of a hydraulic system and an apparatus for measuring the pressure prevailing in the said hydraulic system.

According to a preferred embodiment of the invention, said sensor consists of a hydraulic cylinder, equipped with a system for pressurizing the hydraulic fluid and an apparatus for measuring the pressure applied to said fluid.

The present invention also relates to a method of implementing the device which has just been described.

The process which is the subject of the present invention is essentially characterized in that the pressure applied to the hydraulic fluid is measured under the combined action of the self-weight of the arm-bar system and the buoyancy of Archi II undergone by the said bar, and in that one deduces the -eT “level of the liquid in the container.

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According to a preferred mode of implementation, an initial pressure is applied to the hydraulic fluid and the variation of the pressure in the hydraulic system is measured when the buoyancy increases with the level of the metal.

According to another advantageous modality of implementation, an initial pressure is applied to the hydraulic system at least equal to the maximum possible reduction in pressure corresponding to the maximum Archimedes thrust applied to the bar.

With this in mind, it has proven particularly advantageous to dimension the system in such a way that in the absence of any Archimedes push, the initial pressure applied to the hydraulic system brings the arm into a horizontal or substantially horizontal position.

The invention will be better understood by referring to the appended figure which represents a level detection system in an intermediate basket for continuous casting.

The device shown in the figure comprises an intermediate basket for continuous casting 1 in which a stopper 4 made of refractory material is immersed. This stopper rod is fixed * to an arm 5 articulated in 3 to the support 2 secured to the basket. The detection system according to the invention consists of a hydraulic cylinder 6 disposed between the support 2 and the arm 5 in the vicinity of the articulation 3. In the rest position, the arm 5. is supported on a stop 7 fixed to the support 2. To put the device into service, a pressure is applied to the hydraulic fluid such that the force exerted by the piston of the jack on the arm 5, lifts the latter and brings it into position horizontal.

At this time, the distaff undergoes, on the part of the steel, an Archimedes thrust all the stronger as the level of steel is higher. By applying the equation of the equilibrium of the bending moments around the articulation 3, one can determine the force J which the piston of the jack has to bear and consequently the pressure of the hydraulic fluid. The pressure gauge 8 measuring the pressure \ 9 4 "of the hydraulic fluid can therefore easily be graduated into a quantity representative of the height of the level of steel in the basket 1.

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As indicated in the previous proposal from the same applicant, it is possible, in addition to the pressure gauge 8, to provide a device (not shown in the figure) delivering an electrical signal “which makes it possible to modulate the emptying operation of the bag. feeding and / or ensuring the control of the continuous casting operation.

It goes without saying that the invention is not limited to the embodiments described here, but that it also covers any equivalent technical solution which respects its spirit.

Claims (5)

2. Device according to claim 1 ^ characterized in that the hydraulic system is a hydraulic cylinder whose piston rod acts vertically on said arm, and in that it comprises a system for pressurizing the hydraulic fluid. 3. Method for implementing the device according to either of claims 1 and 2, characterized in that the pressure applied to the hydraulic fluid is measured under the combined action of the self-weight · of the whole arm-bar "and the Archimedes push undergone by the said bar, and in that we deduce the level of the liquid in the container. 4. Method according to claim 3, characterized in that an initial pressure is applied to the hydraulic fluid, in that the variation in the pressure in the hydraulic system is measured under the effect of the variation in the thrust d 'Archimedes applied to the bar by the liquid, and in that we deduce the variation in the level of the liquid in the container. 5. Method according to either of Claims 3 and 4, characterized in that an initial pressure at least equal to the reduction in pressure resulting from the maximum Archimedes thrust is applied to the hydraulic fluid. He applied to the bar. 1 "" " 6. Method according to either of Claims 3 to 5, characterized in that an initial pressure is applied to the hydraulic fluid such that the force applied to the arm brings the latter into a horizontal or substantially horizontal position. ! ^ - - = »! __) 4 f - ·