US 3898366 A
Refractory wear detection apparatus in a refractory lined metallurgical heating system, a portion of the material being processed bridges and forms an electrical junction, between conductor members disposed in the refractory, when a preselected extent of refractory wear is reached.
Description (OCR text may contain errors)
United States Patent Aurini Aug. 5, 1975  METALLURGICAL HEATING SYSTEM 3,078,707 2/1963 Weaver 73/86 WITH REFRACTORY WEAR INDICIA B Ulll c  Inventor: Terrence D. Aurini, Village of g Poland, Ohio P y  Assignee: Youngstown Sheet and Tube ArlmanvEgammer aroldj g h p y Youngstown, Ohio Home gent, 0r 1rm 0 n te ma  Filed: May 8, 1974  App]. No.: 467,916  ABSTRACT Refractory wear detection apparatus in a refractory  US. Cl; 13/35; 13/I lined metallurgical heating System a portion of the  llllt. Cl. H05B 7/18 material b i processed bridges and forms an electri  Fleld of Search 13/35, 1, 9; 73/86 ca] junction between Conductor members disposed in the refractory, when a preselected extent of refractory  References Cited wear is reached UNITED STATES PATENTS 2,915,305 12/1959 Craig 73/86 7 Claims, 4 Drawing Figures I2 2 2A 26A Q 268 t A l6 26c 24C \\\\\Y I k"l"\\\\\\\\\\\\\ METALLURGICAL HEATING SYSTEM WITH REFRACTORY WEAR INDICIA BACKGROUND OF THE INVENTION This invention relates to method andapparatus for metallurgically treating metals in a refractory lined vessel and providing an indication of refractory wear. While the invention is particularly adapted for use in conjunction with refining processes, wherein refractory lined vessels contain a molten charge, it is useful in any system wherein an indication of refractory wear is desirable for safe and/or optimum operation. The invention relates to a more simple and facile technique for providing an indication of refractory wear than has been heretofore available.
There are a number of techniques for measuring r'efractory wear in metallurgical furnaces. However, some of these techniques have certain disadvantages.
One method in.a BOF operation involves tilting the vessel and using calipers to measure the increase in internal diameter of the vessel as the refractory wears. Such a method is not entirely satisfactory because it may not be accurate, i.e., more or less wear may occur at one side of the vessel than on the diametrically opposite side; hence, one side may be worn dangerously low while the opposite side is worn very little and such condition would not be reflected in the measurement. Such technique also involves loss in production time because of the necessity to discontinue operation of the furnace when a measurement is made.
Other techniques involve highly complex or sophisticated equipment, e.g., infrared photography, furnace shell temperature measurement (measuring for hotspots), or radioactive material energy level measurement.
OBJECTS AND SUMMARY OF THE INVENTION It is an object of this invention to provideindicating method and apparatus for indicating extent of refractory wear in a metallurgical heating system without interrupting the operation of the system.
It is a primary object of this invention to prove more simple and facile method and apparatus for indicating when a preselected degree of refractory wear occurs.
Briefly, the objects are obtained by providing a normally open electrical circuit defined by conductor members disposed in the refractory lining of a metallurgical heat treating system, at least one of the conductor members has its terminus positioned in the refractory, away from the interior surface of the furnace, at a point representing that which, when refractory wears away, a signal is desired. In one embodiment, when the refractory wears away to an extent which exposes conductors to electrically conductive material being processed in the system, some of the material bridges the space between the conductors and closes the circuit and thereby energizes the indicia means. In another embodiment, a coating which is electrically conductive, such as iron oxide, may form on the surface of the refractory and serve to complete an electrical circuit between two conductors disposed in the refractory.
DESCRIPTION OF THE DRAWING The invention will be fully understood and further objects and advantages thereof will become apparent when reference is made to the following detailed description and to the accompanying drawing, in which:
e the melting vessel; and
FIG. 2A is a fragmentary portion of FIG. 2, illustrating the manner in which the indicia circuit is energized.
DESCRIPTION OF PREFERRED EMBODIMENTS In FIG. 1, the heating system is shown as comprising a vessel 10 containing a molten metal charge 12. The vessel. 10 is defined by a wall comprising a refractory wall section 14 and an outer metal shell section 16.
, The refractory wear indicia apparatus, generally designated by the numeral 20, is shown as comprising a plurality of electrical conductor members 22 (which for the sake of description are additionally designated by separate letter suffixes), electrically energizable signal means 24, and lead wires 26 (additionally designated by letter suffixes corresponding to the letter suffixes of conductor members 22). The conductor members 22 are electrically conductive and preferably of metal and of sufficient size to provide structural rigidity, e.g., A to 1 inch diameter probe rods.
The conductor members 22 are disposed in the refractory wall 14 and extend toward the face 14 A thereof which forms a portion of the interior surface of the vessel 10. The conductor members 22 and their corresponding lead wires are suitably electrically insulated from the shell 16. In the event the refractory be comprised of electrically conductive material, e.g.,
graphite, the conductor members 22 would also be suitably electrically insulated from the refractory.
In FIG. 1 there are shown three conductor members 22 A, 22 B, and 22 C; however, the number of conductor members 22 may vary depending upon the degree of wear measurement desired. In some embodiments, only two conductor members will be sufiicient.
Other embodiments may require a series of conductors be positioned about the perimeter of the vessel. Still other embodiments may be made by disposing a series of conductors such that, within the series, their terminals are at different distances from a face of 14 A of a vessel 10; in such case each conductor 22, in excess of one, would represent a correspondingly different level of refractory wear for which a signal is desired. A pair of conductors is required for each signal desired; however, one conductor may form a part of more than one pair.
As shown in FIG. 1, the indicia apparatus circuit is normally open because there is no junction between conductor members to complete a signal circuit. As the refractory wears away, due to erosion or other deterioration, and exposes the terminals of conductors 22 A and 22 B, the melt 12 bridges, and forms an electrical junction between the conductors and thereby closes the circuit. When the circuit is closed, the indicia means will be energized and produce a signal.
It should be noted that although the refractory linings may be considered to be generally porous, they are not so porous that the molten charge of the furnace will flow through the refractory interstices and short circuit uninsulated conductor members prematurely. Generally, the molten charge will penetrate about 1/16 inch or less of the refractory at any one stage. Usually, the molten metal will cool and solidify to form a skin near the exposed refractory surface.
In FIG. 1, the charge in the furnace is symbolized as being wholly metallic; however, it will be understood that the system will also work with other electrically conductive materials such as certain metallic oxides, such as iron oxide, and the like. For example, the charge may include an iron oxide bearing slag. In cases where such slag is considered to be more erosive than other constituents of the charge, a series of conductor members may be positioned adjacent the slag line so that earliest penetration to the deepest extent preselected for measurement will be detected and signaled.
In FIG. 2, there is illustrated an embodiment where a charge of scrap metal 32 is melted in the furnace 34 and the conductor members 22 are positioned in the area of greatest potential wear. In some cases where the flame from the melting burner extends across the furnace, the area of greatest potential wear is usually opposite the emitting burner. Also, in some cases, the molten metal may not accumulate in the furnace to a height sufficient for the metal to bridge and form a junction between the detector conductor members; however, generally a metallic oxide layer 30 or skin is continuously formed on the surface of the refractory. The oxide layer will be electrically conductive, particularly at temperature of lO0 F or greater. When the refractory wears away sufficiently to expose the pair of detector conductor members, the oxide layer will form a junction and close the circuit and thereby energize the signal system.
FIG. 1 additionally illustrates the manner in which detector conductor members 22 may be positioned in the bottom wall of a treating vessel. The bottom wall detectors may be used in combination with or instead of the side wall detector members.
What is claimed is:
1. In combination, with a metallurgical heating system including:
a vessel, having a refractory lining, for containing material being processed;
said refractory lining having a face forming a portion of the interior surface of said vessel;
indicia apparatus circuitry for indicating when a preselected extent of wear of said lining is reached without interrupting the operation of said system, which apparatus circuitry is normally electrically open and comprises:
a. external indicia means for producing an electrically generated signal;
b. a pair of conductor members disposed in said lining and electrically connected to said indicia means;
c. at least one of said members extending toward, but short of said face, to a preselected point for which a signal is desired, when the refractory lining covering said one member wears and said one member is exposed to the interior of said vessel;
d. said conductor members being spaced apart and positioned in said refractory lining and of a type such that when electrically conductive material bridges said members an electrical junction is formed and said indicia means is energized.
2. The combination, as described in claim 1, wherein:
said one conductor is positioned for exposure to the interior of said vessel when the maximum tolerable wear of the refractory lining occurs.
3. The combination, as described in claim 1, wherein:
said vessel is adapted to contain a molten steelmaking composition and said conductor members are positioned in an area generally corresponding to the normal slag forming line of the vessel.
4. The combination, as described in claim 1, wherein:
conductor members are positioned in the bottom wall of said vessel 5. The combination, as described in claim 1, wherein:
at least three conductors are disposed in said lining and at least two have their terminal portions at different positions in respect to said interior surface.
6. The combination, as described in claim I, wherein:
at least a portion of said material being processed is electrically conductive and forms means for bridging the conductor members.
7. The combination, as described in claim 1, wherein:
An electrically conductive oxide is disposed on said refractory lining and forms means for bridging said conductor members.