JPH0249394A - Method and device for cooling induction furnace refractory - Google Patents

Abstract

PURPOSE:To prevent the generation of cracks in refractories by measuring the temperatures at plural points of the refractories which is lined to the inner wall of an induction furnace, and operating plural cooling devices independently to cool the entire refractories evenly depending on the measured temperatures. CONSTITUTION:A cooling control device 55 is provided separately from a cooling device 2 furnished to an induction furnace 1 and thermoelectric couples 3, and it furnishes a program controller 5 to deliver value opening signals to flow control valves 18 depending on the signals fed from the thermoelectric couples 3, transducers 23, and a compression air source 24 which is the generating source of the cooling air. The cooling control device 55 can move freely and integrally by using casters 25. Cables 21 extending from the thermoelectric couples 3a to 3c can be connected and disconnected freely to the connection terminals 26a to 26c provided to the cooling control device 55, and the terminals 26a to 26c are connected to program controllers 5a to 5c respectively. The controllers 5a to 5c memorize the optimum cooling properties of the refractories 4 of the induction furnace 1, and at the same time, compare the temperature obtained from the thermoelectric couples 3 and the cooling properties to determine an optimum flow of the cooling air which is delivered to the valves.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a method for cooling refractories for an induction furnace to prevent cracks from occurring in the refractories of an induction furnace when the induction furnace is turned into an empty furnace. Regarding equipment.

[Prior Art] Among crucible-type induction furnaces for melting iron, copper, brass, aluminum, etc., in large-scale induction furnaces for melting 8 tons or more of the above-mentioned metals, the molten metal is discharged and its state is Induction furnaces are installed on the premise that they will not become so-called empty furnaces.

This is because by turning the induction furnace into an empty furnace or by melting metal from an empty furnace state, the refractory lining the inner wall of the induction furnace suffers thermal contraction and thermal expansion due to rapid temperature changes. This is because cracks occur in the refractory due to the addition of heat. In particular, in the case of acidic refractories such as SiOx, from β quartz to α quartz, from α quartz to tritumite,
Tritumite transforms into cristobalite, and with the transformation, the refractory undergoes a rapid volume change and is prone to cracking.

In addition, in small and medium-sized induction furnaces with a melting capacity of 5 tons or less, in the case of acidic refractories for cast iron, the lifespan of the induction part is approximately 25 cooling cycles due to the occurrence of cracks as described above, and the lifespan of the induction furnace is approximately 25 cooling cycles. The longer this happens, the shorter the lifespan of the furnace refractories will be.

Therefore, as a general rule, large-sized induction furnaces should not be cooled in an empty furnace, and small and medium-sized induction furnaces should be cooled to prevent sudden temperature changes.

[Problem to be solved by the invention] For the reasons mentioned above, conventional large-scale induction furnaces do not operate at night,
When the induction furnace is not in use, such as on holidays, it is necessary to keep molten metal in the furnace. Therefore, electric power was required to keep the induction furnace warm even when it was not in operation, and a supervisor was also required to monitor the induction furnace at night, which resulted in high costs.

The present invention was made in order to solve the above-mentioned problems, and uses a method of cooling the induction furnace in an empty furnace so as to prevent the formation of racks that could be fatal to the refractories lining the inner surface of the induction furnace. This makes it possible to use an empty furnace in large induction furnaces, reducing costs and extending the life of the refractories in induction furnaces. The purpose is to provide a cooling device that achieves this goal.

[Means for Solving the Problems and Their Effects] The present invention provides a plurality of temperature measuring means for measuring the temperature of refractories lining the inner wall of an induction furnace, a plurality of cooling means for cooling the refractories, The temperature measuring means is characterized in that it includes a control means for controlling the cooling capacity of the cooling means based on a sent-out temperature signal.

With the above configuration, the control means can uniformly cool the entire refractory by controlling the cooling capacity of the cooling means based on the signal sent by the temperature measuring means.

[Example] In Fig. 1 showing an example of the configuration of the present invention, after the molten metal in the induction furnace l is discharged, the induction furnace 1 is removed from the opening of the induction furnace l.
A cooling device 2 and a thermocouple 3 are inserted into the cavity 1a inside. Note that the thermocouple 3 measures the temperature of the refractory 4 by coming into contact with the refractory 4 lining the inner surface of the induction furnace l.

In the cooling method of the present invention, cracks occur in the refractory 4 based on the temperature of the refractory 4 obtained from the thermocouple 3 and the cooling characteristics of the refractory 4 stored in advance in a program controller 5 connected to the thermocouple 3. In this method, the entire refractory 4 is uniformly cooled by controlling the flow rate of cooling air ejected from the cooling device 2 by the cooling device controller 6 so that the cooling air does not cool.

An embodiment of the cooling device of the present invention for carrying out the above cooling method is shown in FIGS. 2 to 4. In FIGS. 2 to 4, the same components as those shown in FIG. 1 are designated by the same reference numerals.

FIG. 2 is a diagram showing details of the cooling device 2 and thermocouple 3 shown in FIG. 1.

In order to locate the cooling device 2 and the thermocouple 3 in the internal cavity la of the induction furnace l, the pedestal 12 that supports the cooling air population pipe IO and the thermocouple support part 11 has a portal shape and has an appropriate structure. The distance between the leg 12a and the outer circumferential surface IC of the induction furnace I is adjusted in order to align the center axis of the leg 12a whose height can be adjusted with the center axis of the cooling pipe 13, which will be described later, with the center axis of the internal cavity 1a of the induction furnace 1. At the same time, it is provided with a spacer +2b for fixing the frame 12 to the induction furnace l, and the leg portion 12a is attached to a deck 50, for example.
It is installed by standing on the base.

A cooling air inlet pipe lO, which is a pipe for sending cooling air into the induction furnace l, is passed through the center of the frame 12.
It is fixed to a pedestal 12. Further, the cooling air artificial pipe 10 extends to the outside of the pedestal 12 on the side opposite to the induction furnace 1 side.
At the end of the cooling control device 55 shown in FIG. 4, which controls the cooling of the refractories 4 of the induction furnace 1 and separate from the induction furnace 1, there is a flexible A quick joint 15 is attached to the air port I11 so that it can be attached and detached with one touch. Furthermore, a cooling pipe 13 is connected to the other end of the cooling air inlet pipe 10 extending inside the pedestal 12 which is the induction furnace 1 side, so as to be rotatable with respect to the fixed cooling air inlet pipe 10. A rotation joint 16 is attached for this purpose.

The cooling pipe 13 is a pipe that sends cooling air supplied from the cooling air population pipe 10 to the branch pipes 17 of fν number, and when the pedestal 12 is installed on the deck 50, the bottom surface 1 of the induction furnace l
It has a length that does not make contact with b.

The branch pipes 17 are pipes that protrude in the circumferential direction from the outer peripheral surface of the cooling pipe 13 at regular intervals in the longitudinal direction of the cooling pipe 13 in the same row or in any other suitable arrangement. 17a
, the flow control valve 18, the short pipe 17h, and the nozzle 19. A flow control valve 18 for controlling the flow rate of cooling air jetted from the nozzle 19 of each branch pipe I7 is connected to each short pipe 17a connected to the cooling pipe 13, and the flow is directed to the output 1] side of the control valve 18. A short pipe 171] is connected to the short pipe 17b, and a nozzle 19 is connected to the short pipe 17b. The length of each branch pipe 17 is shorter than the radius of the inner diameter of the induction furnace 1, and the cooling pipe 13 is connected to the induction furnace 1.
The length is such that the nozzle 19 does not come into contact with the inner wall of the induction furnace 1 when installed at the center of the induction furnace.

In addition, each flow control valve 18 is connected to a cable 22 for supplying a control signal for adjusting the valve opening, a connection terminal provided on the rotary joint 16, or a connection terminal provided on the rotary joint 16.
It extends from and is connected to the cooling control device 55, not shown in FIG. 4, via an appropriate connection terminal provided separately from the cooling control device 55.

Further, the outlet 19a of the nozzle 19 has a trumpet tube shape,
Furthermore, instead of facing the inner wall of the induction furnace l, as shown in FIG. The nozzle outlets 19a are oriented in the same direction. Therefore, when the cooling air is ejected from the nozzle 19, the cooling pipe 13 rotates in the direction of arrow B shown in FIG. 3, for example. Further, the nozzle I9 may be of a type that sprays the liquid in the form of mist.

Furthermore, as shown in FIG. 2, a thermocouple support is located at a distance within the inner diameter radius of the induction furnace l with the cooling air population pipe lO as the center, and at a position that will not interfere when the branch pipe 17 rotates. 11 extends from the inside of the pedestal 12 toward the induction furnace I side,
The end of the thermocouple support section 11 is fixed to the pedestal 12.

A plurality of thermocouple pressing devices 20 for crimping the tip 40 of the thermocouple 3 perpendicularly to the refractory 4 that is the inner wall of the induction furnace 1 are provided at equal intervals in the longitudinal direction of the thermocouple support portion II. ing.

The length of the thermocouple support KS11 is the same as the length of the thermocouple support KS11.
0, the thermocouple support part 1 is attached to the bottom surface 1b of the induction furnace
The length is such that the ends of 1 do not touch each other. Further, the thermocouples 3 include, for example, thermocouples 3a to 3c, as shown in FIG.
is provided, and the thermocouple 3 is made of, for example, chromel-alumel (C
A) type, so the power generated from each thermocouple 3 is
Each is supplied via a cable 21 to a cooling control device 55 shown in FIG.

The cooling control device 55 shown in FIG. 4 is provided separately from the cooling device 2 and thermocouple 3 provided in the induction furnace 1 described above, and controls each flow rate based on the signal supplied from the thermocouple 3. It is equipped with a program controller 5 and a converter 23 that send a valve opening control signal to the valve 18, a compressed air source 24 that is a source of cooling air, etc., and these are integrally formed and can be freely controlled by providing casters 25. It can be moved to

The cable 21 extending from the thermocouples 3a to 3C is connected to a connecting terminal 26a provided on the surface of the cooling control device 55.
The connecting terminals 26a to 26c are removably connected to the program controllers 5a to 5C.
connected to. Program controller 5a to 5C
The system memorizes the optimum cooling characteristic for the refractory 4 of the induction furnace 1, and determines the optimum flow rate of the cooling air by comparing the temperature obtained from the thermocouple 3 with the cooling characteristic. Program controller 5a to 5C
are connected to converters 23a to 23c that convert signals indicating the determined optimum flow rate into valve opening control signals for flow rate control valves 18a to 18c, and converters 23a to 2
3c are connected to connection terminals 27a to 27c attached to the surface of the cooling control device 55, respectively. And the connection terminals 27a to 27c are connected to the flow control valve 18a.
The cable 22 connected to 18c to 18c is detachably connected.

In addition, the program controllers 5a to 5C have operation 5.
A buzzer 28 which generates a warning sound when an abnormality occurs is connected to a recorder 29 which records the execution state of the program.

Furthermore, an air joint 30 is installed on the surface of the cooling control device 55 to guide the cooling air sent out by the compressed air source 24 to the cooling device 2 (the air hose 14 can be attached or detached thereto).

Note that the converter 23 and compressed air source 24 form a cooling device controller 6.

In the cooling control device 55 configured as described above,
For example, the upper temperature of the refractory 4 of the induction furnace 1 sent by the thermocouple 3a is supplied to the program controller 5a via the cable 21 and the connection terminal 26a. The program controller 5a stores cooling characteristics related to a plurality of refractories 4, including the internal volume of the induction furnace 1, the refractory 4
The operator selects the optimum cooling characteristic that makes the refractory 4 least likely to crack, taking into account factors such as the material, the type of molten metal, and the melting temperature.

The program controller 5a compares the selected optimal cooling characteristic with the upper temperature of the refractory 4 sent out by the thermocouple 3a, and if the difference between the temperature indicated by the optimal cooling characteristic and the upper temperature is large, the refractory Sending a signal to the converter 23a to increase the flow rate of cooling air jetted above the object 4,
Further, when the temperature of the refractory 4 is in a temperature range near the transformation point where thermal contraction or expansion is large, a signal is sent to the converter 23a to reduce the flow rate of the cooling air jetted out in order to slowly cool the refractory 4. On the contrary, when the temperature of the refractory 4 is in a temperature range where there is little thermal contraction or thermal expansion, the converter 23a sends a signal to increase the flow rate of cooling air in order to quickly cool the refractory 4.
Send to.

The converter 23a transmits a valve opening control signal for adjusting the valve opening of the flow control valve 18a to the flow control valve via a connection terminal 27a and a cable 22 in accordance with a signal related to the flow rate of cooling air supplied from the program controller 5a. The flow rate control valve 18a, to which the valve opening control signal is sent to the flow rate control valve 18a, adjusts the valve opening according to the signal.

The program controller 5b is supplied with the temperature at the center of the refractory 4 of the induction furnace l, which is sent out by the thermocouple 3b, and the program controller 5c is supplied with the temperature at the upper part of the refractory 4, which is sent out by the thermocouple 3c. The program controllers 5b and 5c also perform the same operation as the program controller 5a described above, and the flow rate control valve 18b is adjusted accordingly.
and the valve opening degree of 18c is adjusted.

Furthermore, when the thermocouples 3a to 3c detect an abnormal temperature with respect to the stored optimal cooling characteristics, the program controllers 5a to 5c emit a warning sound via the buzzer 28 to inform the operator of the abnormality. generate.

Furthermore, the program records being executed by the program controllers 5a to 5c are recorded in the recorder 29.

Furthermore, by connecting the air hose 14 to the quick joint 30, cooling air is supplied from the compressed air source to the cooling device 2.

Note that the power for operating the cooling control device 55 can be supplied via the outlet 31 from an in-factory power source, for example.

As mentioned above, cooling device 2. Thermocouple 3 and cooling control device 5
By using 5, for example, the L part of the refractory 4 of the induction furnace l,
Since the central part and the lower part can be cooled independently, it is possible to cool the refractory 4 so that the temperature of the refractory 4 is uniform in any part of the refractory 4. By uniformly cooling, it is possible to prevent the occurrence of large cracks, which conventionally tend to occur concentrated in the upper and central parts of the refractory 4. In addition, by uniformly cooling the entire refractory 4, a fine rack is uniformly generated from the top to the bottom of the refractory, but this fine rack is ensured when the temperature is raised again to melt the metal. This prevents molten metal from leaking into the interior from the surface of the refractory 4, causing so-called hot water pouring.

In this embodiment, the medium for cooling the refractory 4 may be air, water, or a colloidal solution of the refractory in water. However, in this case,
It is necessary to completely evaporate the water to be sprayed, the cooling efficiency is good, and the refractory mixed with water can fill up the fine cracks that occur in the refractory 4 or repair the refractory 4. There are some flaws.

Further, in this embodiment, although the thermocouple and the branch pipe are explained on three sides, the present invention is not limited to this.

"Effects of the Invention" The temperature measuring stage measures the temperature at multiple points of the refractory lined on the inner wall of the induction furnace, and based on the measurement results, the control means cools the entire refractory uniformly. By independently controlling the cooling capacity of a plurality of cooling means, even if the induction furnace is used as an empty furnace, it will not be fatal to the refractories or cause racks.

Therefore, large induction furnaces can also be used empty, reducing costs and extending the life of refractories in small and medium sized induction furnaces.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of the present invention, FIG. 2 is a diagram showing the configuration of a cooling device and a temperature measuring section of the present invention, and FIG. 3 is a diagram showing a section A-A in FIG. FIG. 1 is a block diagram showing an example of the configuration of the cooling control device of the present invention. !・Induction furnace, 2. Cooling device, 3. Thermocouple,
1. Refractory, 5. Program controller, 6. Cooling device controller, 55. Cooling control device. Figure 3

Claims (9)

[Claims] (1) When an induction furnace is made into an empty furnace, the temperature of the refractory lined on the inner wall of the induction furnace is measured at multiple points, and based on the measured temperature, the temperature is measured at multiple points so that the entire refractory is cooled uniformly. 1. A method for cooling refractories for an induction furnace, characterized by independently operating cooling means. (2) a plurality of temperature measuring means for measuring the temperature of the refractory lining the inner wall of the induction furnace; a plurality of cooling means for cooling the refractory; and the cooling means based on the signal sent by the temperature measuring means. A cooling device for a refractory for an induction furnace, comprising: a control means for controlling the cooling capacity of the refractory. (3) The control means includes a programmable controller that controls the cooling means in accordance with pre-stored thermal expansion and contraction characteristics of the refractory based on the temperature signal sent by the temperature measuring means. A cooling device for an induction furnace refractory according to claim 2. (4) The cooling device for an induction furnace refractory according to Claims 2 and 3, wherein the cooling means includes a flow rate control valve whose flow rate is controlled by a signal sent by the control means, and a nozzle from which a cooling medium is jetted. (5) The refractory for an induction furnace according to any one of claims 1 to 4, wherein the cooling means rotates with its own blade under the jetting pressure of the cooling medium jetted from the nozzle to uniformly cool the refractory. Cooling method and cooling device. (6) The method and apparatus for cooling an induction furnace refractory according to claim 5, wherein the cooling medium is air. (7) The method and apparatus for cooling refractories for an induction furnace according to claim 5, wherein the nozzle provided in the cooling means is capable of ejecting liquid in a mist form. (8) The method and apparatus for cooling refractories for an induction furnace according to claim 7, wherein the liquid ejected from the nozzle is water. (9) The method and apparatus for cooling refractories for an induction furnace according to claim 7, wherein the liquid ejected from the nozzle melts the refractories in colloidal form.