Specialized metallurgical processes – compositions for use therei – Processes – Process control responsive to sensed condition
Patent
1996-05-22
1997-09-23
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Processes
Process control responsive to sensed condition
73299, 73301, 266 94, 266 99, 340618, C21B 724
Patent
active
056699565
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to apparatus and method for depth or fluid level detection of molten metals. More specifically, the invention relates to a method and apparatus for determining when the fluid level of a metal such as molten iron has reached a desired level in a vessel such as the interior of a torpedo car, ingot mold or furnace.
BACKGROUND OF THE INVENTION
Ceramic lined torpedo cars are commonly utilized to transport molten metal from point to point within a steel mill. Determination of the fluid level or depth of molten metal as it is poured into such a car has been a persistent problem. Overfilling of the car causes the need for costly repairs and disruption of the transporting and steel making operation. For example, if the molten metal spills over the top of the car onto the railroad tracks it often becomes necessary to remove and replace a section of the tracks. Conversely, if the proper depth is not attained, the concentration of additives to the metal, such as desulfurizing agents, may be higher than desired or necessary.
Various proposals such as the use of lasers, light sensors, thermocouples, electromagnetic flux detectors, or electrical circuits have all been found to have shortcomings. All of such detection methods are subject to inaccuracies due to inability to account properly for splashing of molten metal, slag or kish on the metal or for light and the tremendous heat emitted from the metal over long periods of time.
A need thus exists for a cost effective system for determination of the fill level in a torpedo car. Such improvements are also needed for such applications as sensing and controlling the level of metal in other receptacles such as ingot molds, furnaces and ladles.
SUMMARY OF THE INVENTION
A principal object of the present invention is to overcome the above-noted shortcomings and to provide a simple, accurate and cost effective means and method for determining the level of molten metal in a torpedo car. A related object is to provide such a system which avoids inaccurate measurements.
One aspect of the invention relates to the use of gas flow and, more specifically, gas pressure measurement to monitor the level of molten metal in a receptacle. Another aspect is to use the measurement of a drop or, alternatively, and increase in measured pressure within a pressurized conduit as a means of molten metal level detection. A related aspect is to utilize the melting (or alternatively the sealing) of a portion of a conduit extending into a vessel being filled with molten metal as an indication that the level of molten metal has reached the depth at which said conduit is positioned.
A further aspect of the invention involves the use of an orifice to restrict the flow out of a conduit to provide a measurable reference gas pressure in a conduit. A related aspect is to utilize pressure drop occasioned by the melting of the conduit and resultant escape of gas pressure to indicate that a desired depth of molten metal has been attained in a vessel. A yet further aspect of the invention is to provide warning means either visible or audible to alert an operator of the fact that the desired fluid level of molten metal has been obtained so that he will manually stop the pouring of metal into the vessel. Alternatively, the signal produced can be utilized to cause, by electrical control, a cessation of pouring of molten metal into the vessel.
In accordance with still further aspect of the invention a signal can be triggered upon plugging of an gas flow conduit as well as by opening of the conduit due to melting thereof. In accordance with yet a further aspect, a vertically movable device can be used by lowering the same at a controlled rate downwardly toward the surface of a molten metal to accurately measure the depth of metal in a partially filled vessel. In accordance with another aspect, a negative pressure, or partial vacuum can be employed in the practice of the invention instead of a positive pressure. An important advantage of the invention results from th
REFERENCES:
patent: 3780581 (1973-12-01), Acre et al.
patent: 5167155 (1992-12-01), Rodgers
patent: 5198749 (1993-03-01), Guthrie et al.
Behring James A.
Falk William
Andrews Melvyn
Midwest Instrument Co., Inc.
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