JP2014190977A - Temperature measurement structure and shelf hanging detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of securing safety during an operation and achieving energy saving and improvement of the quality of a molten metal in a metal melting furnace.SOLUTION: A temperature measuring structure 100 includes: a fire-resistant base member 20 engaged with a fire brick in a state that a lower end part 20a is inserted to an opening part 13 opened in a fire brick 12 laid on the furnace floor 11 of a melting furnace 10; a fire-resistant protecting tube 30 connecting a lower end opening part 31 to a hole part 21 provided in a direction roughly vertical to the base member 20 and erected on the base member 20 in a state that an upper end part 32 is blocked; a plurality of temperature sensors 41, 42 arranged in the protecting tube 30; and an alumina-based dry stamp layer 50 formed on the fire-resistant fire brick 12 in a state that the protecting tube 30 and the base material 20 are embedded to the roughly same height as that of the upper end part 32 of the protecting pipe 30.

Description

  The present invention relates to a temperature measuring structure suitable for continuously measuring the internal temperature of molten metal in a metal melting furnace and a shelf hanging detection method using the same.

  In the operation of a metal melting furnace, accurately grasping the internal temperature of the molten metal in the melting furnace is extremely important for thorough safety operation and molten metal quality control. For this reason, various temperature measuring techniques have been developed in the past, but there are, for example, a temperature measuring device described in Patent Document 1 or a temperature measuring device described in Patent Document 2 as those relating to the present invention.

  The temperature measuring device described in Patent Document 1 includes a cylindrical ceramic protective tube having a hollow portion with a closed end portion, and a temperature sensor disposed in the hollow portion of the protective tube, and accommodates molten metal. The protective tube is embedded in a refractory member laminated inside the refractory brick constituting the molten container, and the rear end of the protective tube is fixed to the refractory brick. This temperature measuring device has the advantage of being able to measure the temperature of molten metal accurately at low cost with good responsiveness and continuously.

  The temperature measuring device described in Patent Document 2 is open to the front end surface of the tube that comes into contact with the molten metal, and has a heat-resistant tube having a small diameter through-hole formed along the tube axis from the front end surface of the tube to the rear end surface of the tube, An optical fiber for detecting the temperature of the molten metal and a temperature calculation unit for calculating the molten metal based on temperature information from the optical fiber are provided.

  By the way, in the metal melting furnace in operation, among the charged raw metal, the raw metal located near the bottom of the melting furnace is melted to become a molten metal, while the raw metal located in the surface layer portion remains undissolved. A so-called “shelf hanging” phenomenon may occur in which a cross-linked state occurs. If heating is continued with shelves generated, not only electric energy is wasted, but also the pressure of the high-temperature air layer formed between the overheated molten metal and the bridging part increases significantly, It can explode and cause a serious accident.

  In order to prevent the occurrence of shelf hanging, it is necessary to constantly check the melting state of the surface layer portion of the raw material metal charged into the melting furnace. Since it is difficult to distinguish from the surface layer portion of the raw material metal when the occurrence of the occurrence of shelves, it is difficult to determine the presence or absence of the shelf hanging only by visual observation of a general worker. For this reason, judgments are made on the site based on the intuition of skilled workers, but it is difficult to achieve perfection. Then, the technique which avoids generation | occurrence | production of shelf hanging is proposed by measuring the temperature of the molten metal in a melting furnace, without depending on the intuition of a skilled worker (for example, refer patent document 3).

JP 2008-267986 A JP 2008-45971 A JP-A-6-82171

  In the melting furnace in actual operation, the state where the high-temperature molten metal and high-temperature air are alternately switched is repeated continuously, so that the protective tube with the built-in temperature sensor is exposed to a harsh atmosphere in the melting furnace. As a result, it is oxidized by high-temperature air or melted in molten metal. For this reason, during operation of the melting furnace, accurate temperature measurement may become impossible or impossible due to oxidation or melting damage of the protective tube.

  In addition, the actual melting furnace is often operated continuously, and the refractory material forming the melting furnace itself is maintained at a high temperature, so in the contact area between the protective tube containing the temperature sensor and the refractory material In many cases, the materials forming the two materials react with each other, damage the protective tube, and lose the protective function.

  Such a problem can be solved to some extent by using the temperature measuring device described in Patent Document 1 or the temperature measuring device described in Patent Document 2, but in the technical field to which the present invention belongs, The demand for ensuring safety during operation, energy saving, and improving the quality of the molten metal is increasing year by year, and the temperature measuring device described in Patent Document 1 and the temperature measuring device described in Patent Document 2 do not sufficiently meet the demand. There is a real situation.

  On the other hand, the shelf hanging phenomenon that may occur in the melting furnace during operation can be prevented by using the technique described in Patent Document 3, but from the viewpoint of ensuring safety, it is perfect. Is required.

  Therefore, the problem to be solved by the present invention is to provide a technique capable of saving energy and improving molten metal quality and ensuring safety during operation in a metal melting furnace.

  The temperature measuring structure of the present invention is a refractory base member locked to the refractory brick in a state where a lower end portion is inserted into an opening portion opened in the refractory brick laid on the hearth of the melting furnace, A fireproof protective tube erected on the base member in a state where a lower end opening is inserted into a hole provided in the base member in a substantially vertical direction and the upper end is closed, and the protective tube It is characterized by comprising a temperature sensor arranged, and a refractory material layer formed on the refractory brick in a state where the protective tube is buried to a height substantially equal to the upper end of the protective tube.

  With such a configuration, the temperature sensor located on the hearth of the melting furnace makes it possible to continuously measure the temperature of the molten metal in the melting furnace with good responsiveness. Since the heating energy of the melting furnace can be controlled based on the above and excessive heating can be avoided, energy saving can be achieved. Furthermore, by continuously and accurately measuring the internal temperature of the molten metal in the melting furnace, it is possible to keep the operating state of the melting furnace stable and to thoroughly control the molten metal quality, so that the molten metal quality can be improved. it can.

  Here, it is desirable that the protective tube is formed of ceramics including any one or more of silicon nitride, silicon carbide, aluminum oxide, and yttrium oxide. Such a configuration is effective in improving durability because the protection tube can be prevented from being oxidized or melted and reaction between the protection tube and the refractory material layer.

  In addition, it is desirable that at least two temperature sensors be displaced in the axial direction of the protective tube in the protective tube. With such a configuration, it becomes possible to measure the temperature in a parallel state by at least two temperature sensors having different distances from the bottom surface (bottom layer portion) of the molten metal in the melting furnace. The accuracy can be further improved. In addition, when an abnormality occurs in the upper temperature sensor due to molten metal intrusion or the like, it can be detected by the lower temperature sensor, so that a quick response is possible.

  Furthermore, it is desirable to arrange the temperature sensor in the protective tube in a state of being housed in an insulating tubular body.

  On the other hand, it is desirable that the thickness of the upper end portion of the protective tube is larger than the outer diameter of the protective tube and not more than 30% of the thickness of the refractory material layer.

  Further, it is desirable that the thickness of the upper end portion of the protective tube is larger than the thickness of the other portion of the protective tube.

  Furthermore, it is desirable to provide a flat portion perpendicular to the axis of the protective tube at the upper end of the protective tube.

  Next, in the shelf hanging detection method of the present invention, any one of the temperature measuring structures described above is constructed in the hearth region of the melting furnace, and the internal temperature of the molten metal accommodated in the melting furnace is determined by the temperature sensor. A continuous measurement is performed, and an alarm signal is issued when the measured value of the temperature sensor exceeds a preset value.

  It has been confirmed that the temperature of the molten metal rises excessively when shelf hanging occurs in the melting furnace during operation. Therefore, with the above configuration, an alarm signal is generated when the temperature of the molten metal in the melting furnace continuously measured by a temperature sensor located in the hearth of the melting furnace exceeds a preset value. Since the occurrence of shelf hanging can be detected and dealt with quickly, accidents caused by shelf hanging can be prevented and safety during operation can be ensured. Further, if it becomes possible to stop the heating of the melting furnace after detecting the occurrence of the shelf hanging, excessive heating can be avoided, so that energy saving can be achieved. In addition, when the said alarm signal is emitted, it can also be set as the structure which outputs an alarm sound and alarm light simultaneously, or the heating means of a melting furnace is stopped automatically.

  According to the present invention, in a metal melting furnace, it is possible to provide a technique capable of saving energy and improving the quality of molten metal and ensuring safety during operation.

1 is a partially omitted vertical sectional view showing a melting furnace using a temperature measuring structure according to a first embodiment of the present invention. It is a partially expanded view of FIG. FIG. 3 is an exploded perspective view in which a part of the region shown in FIG. 2 is omitted. It is sectional drawing in the AA in FIG. FIG. 3 is a partially omitted side view showing a temperature sensor and a tubular body in FIG. 2. It is the figure seen from the arrow B direction in FIG. It is a graph which shows the relationship between the measured value obtained using the temperature measuring structure shown in FIG. 1, and elapsed time. It is a partially omitted vertical sectional view showing a melting furnace using a temperature measuring structure according to a second embodiment of the present invention. FIG. 9 is a partially enlarged view of FIG. 8. FIG. 10 is a partially omitted side view showing the temperature sensor and the tubular body in FIG. 9. It is a partially expanded vertical sectional view which shows the melting furnace using the temperature measuring structure which is 3rd Embodiment of this invention.

  Hereinafter, based on FIGS. 1-7, the temperature measuring structure 100 which is 1st Embodiment of this invention is demonstrated. As shown in FIGS. 1-6, the temperature measuring structure 100 of this embodiment is the state which inserted the lower end part 20a in the opening part 13 established in the refractory brick 12 laid in the hearth part 11 of the melting furnace 10. As shown in FIG. With the fire-resistant base member 20 locked to the fire-resistant brick 12 and the lower end opening 31 connected to the hole 21 provided in the base member 20 in a substantially vertical direction and the upper end 32 closed. A protective tube 30 that stands up on the base member 20, a plurality of temperature sensors 41 and 42 disposed in the protective tube 30, and the protective tube 30 up to a height substantially equal to the upper end portion 32 of the protective tube 30. And an alumina-based dry stamp layer 50 which is a refractory material layer formed on the refractory brick 12 in a state where the base member 20 is embedded.

  In the melting furnace 10, a copper radiating plate 15 is laid on a bottomed cylindrical iron door 14, and a plurality of refractory bricks 12 are laminated on the copper radiating plate 15 to form a refractory brick layer 60. It is manufactured by forming an alumina-based dry stamp layer 50 on the surface. The molten metal M is formed in the region covered with the dry stamp layer 50 in the melting furnace 10. Further, a hot water leak sensor 17 for detecting a leak of the molten metal M is disposed on the alumina-based dry stamp layer 50.

  As shown in FIGS. 2 and 3, the base member 20 has a columnar insertion portion 20b and a columnar shape having an outer diameter smaller than that of the insertion portion 20b integrally formed in a state slightly decentered on the insertion portion 20b. Projecting portion 20c. A hole 21 is formed from the upper surface of the protruding portion 20c toward the insertion portion 20b, and the lower portion of the hole 21 is coaxially connected to a sensor insertion hole 22 opened on the lower surface of the insertion portion 20b.

  A circular opening 13 is formed in the upper surface 12 a of the refractory brick 12 located at the approximate center of the uppermost portion of the refractory brick layer 50 formed in the melting furnace 10, and the base member 20 is formed in the opening 13. The base member 20 is attached to the refractory brick 12 by inserting the insertion portion 20b. Thereby, the upper surface 20d of the insertion portion 20b is substantially flush with the upper surface 12a of the refractory brick 12, and the projecting portion 20c stands up from the upper surface 12a of the refractory brick 12 in a substantially vertical direction.

  The protective tube 30 is formed of a composite ceramic that is fired using a submicron powder of silicon nitride, silicon carbide, aluminum oxide, and yttrium oxide as a raw material, and the thickness 32t of the upper end portion 32 of the peripheral wall portion 33 that is the other portion. The thickness is larger than 33t. As shown in FIGS. 4 and 5, the plurality of temperature sensors 41 and 42 are accommodated in an insulating tubular body 40 and are contained in a cavity 34 formed in a region including the axis 30 c of the protective tube 30. It arrange | positions in the state displaced to the axial center 30c direction of the protective tube 30. FIG. Further, the upper end portion 32 of the protective tube 30 is provided with a flat portion 35 orthogonal to the axis 30 c of the protective tube 30. Therefore, the plurality of temperature sensors 41 and 42 are built in the protective tube 30.

  As shown in FIGS. 4, 5 and 6, the tubular body 40 is formed with four holes 43 and 44 parallel to the axis 40c at equal intervals around the axis 40c. At portions near the distal end portion 40a of the tubular body 40, substantially bowl-shaped notches 45 and 46 are provided at two positions displaced in the direction of the axis 40c. The two holes 43 open to the notch 45 on the tip 40 a side, and the two holes 44 open to the notch 46 below the notch 45.

  The temperature sensors 41 and 42 are both thermocouples, and one temperature sensor 41 is accommodated in the tubular body 40 with a pair of metal wires 41a inserted through the holes 43 and the contact portions 41b disposed in the notches 45, respectively. The other temperature sensor 42 is accommodated in the tubular body 40 with the pair of metal wires 42a inserted into the holes 44 and the contact portions 42b disposed in the notches 46, respectively.

  As shown in FIG. 1 and FIG. 2, in the temperature measuring structure 100, a protective tube 30 including temperature sensors 41 and 42 is disposed on the hearth 11 of the melting furnace 10 and provided at the upper end 32 of the protective tube 30. Since the formed flat surface 35 and the upper surface 50a of the alumina-based dry stamp layer 50 are formed so as to be substantially in the same plane, the internal temperature of the molten metal M in the melting furnace 10 can be continuously and accurately measured. It is also excellent in responsiveness.

  In addition, the temperature sensors 41 and 42 located on the hearth 11 of the melting furnace 10 can continuously measure the temperature of the molten metal M in the melting furnace 10 with good responsiveness. If the heating energy of the melting furnace 10 is controlled based on the above, excessive heating can be avoided and energy saving can be achieved. Furthermore, by continuously and accurately measuring the internal temperature of the molten metal M in the melting furnace 10, the operation state of the melting furnace 10 can be kept stable and the molten metal quality can be thoroughly controlled. Can be planned.

  Further, as shown in FIG. 2, the thickness 32t of the upper end portion 32 of the protective tube 30 is made larger than the thickness 33t of the peripheral wall portion 33, and the protective tube 30 is necessary for temperature measurement during operation of the melting furnace 10. Since only the minimal flat portion 35 is in contact with the molten metal M, the protective tube 30 is less likely to be oxidized or melted by the high temperature air, and has excellent durability. Demonstrate. Further, since the protective tube 30 is formed of a composite ceramic fired using silicon nitride, silicon carbide, aluminum oxide and yttrium oxide submicron powders as a raw material, not only the above-described oxidation and melting damage can be prevented, but also high temperature. The reaction with the alumina-based dry stamp layer 50 in the state does not occur, and the durability is excellent.

  Further, the plurality of temperature sensors 41 and 42 are accommodated in the insulating tubular body 40, and the direction of the axis 30 c of the protective tube 30 is within the cavity 34 formed in the region including the axis 30 c of the protective tube 30. It is possible to measure the temperature in a parallel state by a plurality of temperature sensors 41 and 42 having different distances from the bottom surface of the molten metal M in the melting furnace 10. Temperature measurement accuracy can be obtained. In addition, when an abnormality occurs in the upper temperature sensor 41 due to intrusion of the molten metal or the like, it can be detected by the lower temperature sensor 42, so that a quick response can be made.

  Next, when the relationship between the measured values by the temperature sensors 41 and 42 constituting the temperature measuring structure 100 and the elapsed time is graphed, a result as shown in FIG. 7 is obtained. When the melting furnace 10 is operating normally, the measured values of the temperature sensors 41 and 42 change while moving up and down in a normal temperature range (for example, a range of 1200 to 1400 ° C.) in FIG.

  On the other hand, when shelf hanging occurs in the melting furnace 10 in operation, the temperature of the molten metal M rises excessively as shown by the broken line portion X in FIG. 7, and the upper limit of the normal temperature range (for example, 1400 ° C.). ) Has been empirically confirmed to enter a dangerous temperature range (for example, a range of 1500 ° C. or more).

  Therefore, in the present embodiment, the internal temperature of the molten metal M in the melting furnace 10 is continuously measured by the temperature sensors 41 and 42, and the measured values of the temperature sensors 41 and 42 are set to preset values (for example, 1400). When the temperature exceeds (° C.), an alarm signal is generated. Therefore, when a shelf hang occurs in the melting furnace 10 in operation, an on-site worker can immediately detect it with the alarm signal, and thereafter, it is possible to take a countermeasure quickly. Accidents caused by hanging the rack can be prevented, and safety during operation can be ensured.

  Furthermore, when the alarm signal is issued, excessive heating can be avoided by providing means for automatically stopping or relaxing the heating function of the melting furnace 10 based on the warning signal. Can be planned. The above-mentioned “preset value” is a temperature used as a criterion for detecting the occurrence of the hanging of the shelf, but is set as appropriate according to the structure and scale of the melting furnace 10 or the type of the molten metal M. can do.

  Next, based on FIG. 8 to FIG. 10 and FIG. 11, a temperature measuring structure 200 that is the second embodiment of the present invention and a temperature measuring structure 300 that is the third embodiment will be described. In addition, in the temperature measurement structure 200, about the part which is common in the temperature measurement structure 100 mentioned above, the code | symbol same as the code | symbol in FIGS.

  As shown in FIG. 8 and FIG. 9, in the temperature measuring structure 200, the refractory brick with the lower end portion 20 a inserted in the opening portion 13 opened in the refractory brick 12 laid on the hearth portion 11 of the melting furnace 10. The base member in a state where the lower end opening portion 71 is connected to the hole portion 21 provided in the base member 20 in a substantially vertical direction and the upper end portion 72 is closed. 20 and a plurality of temperature sensors 41, 42 disposed in the protective tube 70, and a protective tube up to substantially the same height as the flat portion 75 of the upper end portion 72 of the protective tube 70. 70 and an alumina-based dry stamp layer 50 which is a refractory material layer formed on the refractory brick 12 in a state where the base member 20 is embedded.

  As shown in FIGS. 8 and 9, the protective tube 70 is formed of a composite ceramic that is fired from a submicron powder of silicon nitride, silicon carbide aluminum oxide, and yttrium oxide, as with the protective tube 30. The thickness 72t of 72 is made larger than the thickness 73t of the peripheral wall portion 73 which is the other part. The plurality of temperature sensors 41 and 42 are displaced in the direction of the axis 70 of the protective tube 70 in the cavity 74 formed in the region including the axis 70c of the protective tube 70 while being accommodated in the insulating tubular body 80. It is arranged in the state. Further, the upper end portion 72 of the protective tube 70 is provided with a flat portion 75 orthogonal to the axis 70 c of the protective tube 70. Furthermore, the thickness 72t of the upper end portion 72 of the protective tube 70 is larger than the outer diameter 70a of the protective tube 70 and 30% or less of the thickness 50t of the refractory material layer (alumina-based dry stamp layer 50).

  As shown in FIG. 10, in the tubular body 80, four holes 83 and 84 parallel to the axis 80c are formed at equal intervals around the axis 80c. At portions near the distal end portion 80a of the tubular body 80, substantially bowl-shaped notches 85 and 86 are provided at two positions displaced in the direction of the axial center 80c. The two holes 83 open to the notch 85 on the tip 80 a side, and the two holes 84 open to the notch 86 below the notch 85.

  One temperature sensor 41 is accommodated in the tubular body 80 with the pair of metal wires 41a inserted into the holes 83 and the contact portions 41b disposed in the notches 85, and the other temperature sensor 42 is paired with the pair of metal wires 42a. Are inserted into the holes 84 and accommodated in the tubular body 80 in a state in which the contact portions 42b are disposed in the notches 86. Further, the apex portion of the contact portion 41 b of the temperature sensor 41 is disposed at the same height as the upper end portion of the notch portion 85 (the tip portion 80 a of the tubular body 80), and the apex portion of the contact portion 42 b of the temperature sensor 42 is the notch portion 86. It is arranged at the same height as the upper end portion of. Therefore, as shown in FIG. 9, when the tubular body 80 in which the temperature sensors 41 and 42 are accommodated is incorporated in the cavity portion 74 of the protective tube 70, the apex portion of the contact portion 41 b of the temperature sensor 41 is the protective tube 70. It will be in the state contact | abutted to the ceiling surface (lower surface 76 of the upper end part 72) of the cavity part 74. FIG.

  In the temperature measuring structure 200 shown in FIGS. 8 to 10, the thickness 72 t of the upper end 71 of the protective tube 70 containing the temperature sensors 41 and 42 is larger than the outer diameter 70 a of the protective tube 70, and the refractory material layer. Since the thickness of the (alumina-based dry stamp layer 50) is 30% or less of the thickness 50t, the internal temperature of the molten metal M in the melting furnace 10 (see FIG. 8) can be continuously and accurately measured, and the responsiveness. And excellent durability.

  Moreover, since the temperature of the molten metal M in the melting furnace 10 can be continuously measured with high responsiveness by the temperature sensors 41 and 42 located in the hearth part 11 of the melting furnace 10, as described above, the shelf It is possible to accurately detect the temperature rise of the molten metal M when suspension occurs and take quick action, prevent accidents caused by shelf suspension, and ensure safety during operation. it can. Moreover, since the occurrence of shelf hanging can be detected and excessive heating of the melting furnace can be avoided, energy saving can be achieved. Furthermore, by continuously and accurately measuring the internal temperature of the molten metal M in the melting furnace 10, the molten metal quality can be thoroughly controlled, which is effective for improving the molten metal quality.

  Furthermore, as described above, the plurality of temperature sensors 41, 42 are accommodated in the insulating tubular body 80, and the protective tube 70 is formed in the hollow portion 74 formed in the region including the axis 70 c of the protective tube 70. Therefore, the temperature measuring accuracy is also good.

  As shown in FIGS. 7 and 8, the size of each part in the temperature measuring structure 200 of the melting furnace 10 is not limited, but in the present embodiment, the inner diameter 10 a of the melting furnace 10 (the portion in which the molten metal M is accommodated). The inner diameter is 1100 mm, the thickness of the refractory material layer (alumina-based dry stamp layer 50) is 160 mm, the length L from the flat portion 75 at the upper end of the protective tube 70 to the lower end portion 20 a of the base member 20 is 180 mm, The thickness 60t of the brick layer 60 is 130mm, the thickness of the copper radiation plate 15 is 15mm, the thickness of the iron door 14 is 20mm, the outer diameter 70a of the protective tube 70 is 22mm, and the thickness 72t of the upper end 72 is 25mm. It is said.

  Next, based on FIG. 10, the temperature measuring structure 300 which is 3rd Embodiment of this invention is demonstrated. As shown in FIG. 10, the temperature measurement structure 300 is obtained by replacing the tubular body 80 constituting the temperature measurement structure 200 shown in FIG. 8 with a tubular body 90. The tubular body 90 omits one notch 86 of the tubular body 80 shown in FIG. 8, the notch 85 is provided on the tip 90 a side, and the temperature sensor 41 is in a state where the contact 41 b is disposed in the notch 85. The tubular body 90 is accommodated. Other structures and functions are the same as those of the temperature measuring structure 200.

  In the temperature measurement structure 300 shown in FIG. 10, since one temperature sensor 41 is used, the manufacturing cost can be reduced, and an accurate continuous temperature measurement value can be obtained while being a simple structure. Can do.

  The temperature measuring structures 100, 200, 300 and the temperature measuring method described with reference to FIGS. 1 to 10 illustrate the present invention, and the temperature measuring structure and the temperature measuring method of the present invention are the above-described temperature measuring structures. It is not limited to 100, 200, 300 and the temperature measuring method.

  The temperature measuring structure and the shelf hanging detection method using the temperature measuring structure of the present invention can be widely used in various metal industries using a melting furnace for melting various metals such as copper and cast iron.

DESCRIPTION OF SYMBOLS 10 Melting furnace 10a Inner diameter 11 Hearth part 12 Refractory brick 12a, 20d, 50a Upper surface 13 Opening part 14 Iron door 15 Copper radiation plate 16 Refractory brick layer 17 Molten water sensor 20 Base member 20a Lower end part 20b Insertion part 20c Protrusion part 21 Hole Part 22 Sensor insertion hole 30, 70 Protective tube 30c, 40c, 80c Axle 31, 71 Lower end opening part 32, 72 Upper end part 32t, 33t, 50t, 72t, 73t Thickness 33, 73 Peripheral wall part 34, 74 Cavity part 35 , 75 Plane portion 40, 80, 90 Tubular body 40a, 80a Tip portion 41, 42 Temperature sensor 41a, 42a Metal wire 41b, 42b Contact portion 43, 44 Hole 45, 46, 85, 86 Notch portion 50 Alumina-based dry stamp layer (Fireproof material layer)
60 Refractory brick layer 76 Lower surface 100 Temperature measuring structure M Molten metal

Claims (8)

  A refractory base member locked to the refractory brick in a state where a lower end portion is inserted into an opening formed in the refractory brick laid on the hearth of the melting furnace, and a substantially vertical direction to the base member A fire-resistant protective tube erected on the base member in a state where the lower end opening is inserted into the hole portion provided in the closed portion and the upper end portion is closed; a temperature sensor disposed in the protective tube; A temperature measuring structure comprising: a refractory material layer formed on the refractory brick in a state where the protective tube is embedded to a height substantially equal to an upper end portion of the protective tube.   The temperature measuring structure according to claim 1, wherein the protective tube is formed of a ceramic containing one or more of silicon nitride, silicon carbide, aluminum oxide, and yttrium oxide.   The temperature measuring structure according to claim 1 or 2, wherein at least two temperature sensors are arranged in the protective tube so as to be displaced in an axial direction of the protective tube.   The temperature measuring structure according to any one of claims 1 to 3, wherein the temperature sensor is disposed in the protective tube in a state of being housed in an insulating tubular body.   The temperature measuring structure according to any one of claims 1 to 4, wherein a thickness of an upper end portion of the protective tube is larger than an outer diameter of the protective tube and 30% or less of a thickness of the refractory material layer.   The temperature measuring structure according to any one of claims 1 to 5, wherein a thickness of an upper end portion of the protective tube is larger than a thickness of another portion of the protective tube.   The temperature measuring structure in any one of Claims 1-6 which provided the plane part orthogonal to the axial center of the said protective tube in the upper end part of the said protective tube.   Constructing the temperature measuring structure according to any one of claims 1 to 7 in a hearth region of a melting furnace, continuously measuring the internal temperature of the molten metal accommodated in the melting furnace with the temperature sensor, The shelf hanging detection method characterized by issuing an alarm signal when the measured value of the temperature sensor exceeds a preset value.

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