WO2015170549A1

WO2015170549A1 - Ladle heating device

Info

Publication number: WO2015170549A1
Application number: PCT/JP2015/061211
Authority: WO
Inventors: 岡田　民雄; 龍雲朴; 正晴伊藤
Original assignee: 日本坩堝株式会社
Priority date: 2014-05-08
Filing date: 2015-04-10
Publication date: 2015-11-12
Also published as: JP2015213921A; CN106232265A; JP5832588B2

Abstract

Provided is a ladle heating device having good heat efficiency and not causing significant degradation of a work environment. A ladle heating device (1) is provided with: a lid (2) for closing the upper opening (11) of a ladle (10); an electrical resistance heating type heater (3) mounted to the lid (2) and heating the inside of the ladle (10); and a protective cover (4) mounted to the lid (2) so as to surround the electrical resistance heating type heater (3).

Description

Ladle heating device

The present invention relates to a ladle heating device for preheating and keeping warm a ladle used to convey or supply molten metal (molten metal).

In a foundry, a ladle generally receives molten metal (molten metal) from a melting furnace or a previous furnace and transports it to a casting site and directly pours (pours) it into a mold or the like. Used to transfer to pots and molten metal holding furnaces. For example, if the temperature of the molten metal is lowered by 100 ° C. during the conveyance of the molten metal, melting at a temperature higher by 100 ° C. than the casting temperature necessary at the casting site is required. In a melting furnace such as a cupola or induction furnace, You will be forced to operate.

Therefore, in this type of ladle, when the molten metal is transferred from the melting furnace, preheat the ladle so that the refractory lined in the ladle does not lose heat and the molten metal temperature suddenly drops. Thermal insulation is performed. The preheating and warming of the ladle is generally done by heating the refractory lined with a gas burner, but with the gas burner, the time for hot combustion gas to accumulate in the ladle is short. Because it escapes to the outside with high-temperature combustion gas, the heating efficiency is poor, and the working environment is also inferior, such as high temperature, air pollution, and noise. Therefore, Patent Document 1 proposes a technique for sealing the inside of the ladle with a lid, inserting a bipolar electrode into the ladle so as to penetrate the lid, and heating the inside of the ladle by arc discharge. .

JP 2012-55908 A

However, when the inside of the ladle is heated using arc discharge, it is desirable to supply an inert gas into the ladle to prevent arc stability and electrode surface oxidation. It is difficult to preheat. Therefore, there is a demand for a ladle heating device that is thermally efficient in the atmosphere and does not significantly degrade the working environment.

This invention was made paying attention to the above-mentioned problem, and it aims at providing the ladle heating apparatus which has favorable thermal efficiency and can prevent the working environment from remarkably deteriorating.

The above object of the present invention is to cover the ladle with an inlet for molten metal at the top, cover the inlet, an electric resistance heating heater attached to the lid and heating the inside of the ladle, It is achieved by a ladle preheating device comprising a protective cover attached to the lid portion so as to surround the electric resistance heater.

In a preferred embodiment of the present invention, the protective cover is horizontally extended between a plurality of vertical frame members that are arranged to surround the electric resistance heater and extend in the vertical direction, and the plurality of vertical frame members. It is characterized by comprising a plurality of horizontal frame members to be passed.

In a further preferred embodiment of the present invention, the horizontal frame member is bridged on the lower ends of the plurality of vertical frame members.

In a further preferred embodiment of the present invention, the apparatus further comprises a support stand that supports the lid from below and holds the electric resistance heater in a suspended state.

In a further preferred embodiment of the present invention, a heat insulating material is provided on the surface of the lid that is in contact with the ladle.

According to the ladle heating apparatus of the present invention, the inside of the ladle is heated by the electric resistance heating heater attached to the lid while closing the opening of the ladle with the lid, so that heat can be prevented from escaping to the outside. . Therefore, the inside of the ladle can be efficiently heated and heated by energizing the electric resistance heating type heater, so that it is possible to prevent a significant deterioration of the working environment which is a concern during heating by the burner. Moreover, since it can heat in air | atmosphere, it is not necessary to make the inside of a ladle into inert gas atmosphere like the heating by arc discharge. In addition, since the electrical resistance heater is surrounded by the protective cover, it can be prevented that the electrical resistance heater hits something and is damaged when the ladle heating device is transported or attached to the ladle. .

It is a perspective view of the ladle heating device concerning one embodiment of the present invention. It is a schematic sectional drawing of a ladle. It is a top view of the ladle heating apparatus of FIG. FIG. 4 is a schematic sectional view taken along line AA in FIG. 3. FIG. 4 is a schematic sectional view taken along line BB in FIG. 3. It is a schematic sectional drawing at the time of attaching the ladle heating apparatus to the ladle. It is a perspective view of a support stand.

Hereinafter, a ladle heating apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings. The ladle heating apparatus 1 is for heating the ladle 10 which conveys a molten metal (molten metal) from a melting furnace or a molten metal holding furnace (not shown) to a casting site. That is, the ladle 10 is preheated and kept warm so that the temperature of the high temperature molten metal does not drop rapidly in the ladle 10 when the molten metal is transferred from the melting furnace at the molten metal production site to the ladle 10. As shown in FIG. 1, the ladle heating apparatus 1 includes a lid 2, at least one electric resistance heating heater 3, and a protective cover 4.

First, as shown in FIG. 2, the ladle 10 is a bottomed cylindrical container having an internal space in which molten metal can be accommodated and having an opening 11 at the top. The ladle 10 is made of a metal casing 10A such as steel, a heat insulating material 10C such as heat insulating brick, ceramic fiber, heat insulating board and mortar, and a heat resistant heat insulating material 10B made of a heat resistant material such as a castable refractory or a plastic refractory. It is formed with a lining. The ladle 10 is provided with a pouring part 12 capable of pouring the molten metal accommodated in the internal space to the outside. By tilting the ladle 10, the molten metal in the ladle 10 can be discharged to the outside from the opening (spout port) at the tip of the pouring part 12. The upper opening 11 of the ladle 10 is closed by a lid (not shown) as necessary.

As shown in FIGS. 1 and 3 to 6, the lid portion 2 is formed in a size that can cover the upper opening 11 of the ladle 10, and closes the upper opening 11 of the ladle 10. The space is sealed as much as possible so that the heat is not released outside the ladle 10 when the ladle 10 is heated. In addition, the inner space of the ladle 10 does not need to be completely sealed. The lid 2 is formed by lining a heat insulating material 21 on an outer skin 20 made of metal such as steel. The heat insulating material 21 is disposed on the surface of the lid portion 2 on the side in contact with the ladle 10. As the heat insulating material 21, for example, ceramic fiber, heat insulating castable, or the like can be used. By making the lid part 2 into a two-layer structure of the outer skin 20 and the heat insulating material 21, when the ladle 10 is heated, the heat can be effectively confined in the internal space of the ladle 10 and the ladle 10 can be efficiently heated. . The lid 2 is appropriately formed with various through holes 23 through which a part of the electric resistance heater 3 and a part of the protective cover 4 penetrate. In addition, a pair of insertion portions 22 having fork pockets for inserting a fork portion of a forklift are provided on the upper surface of the lid portion 2.

As shown in FIGS. 1 and 6, the electric resistance heater 3 is a heating means formed by a heating element made of a conductive material that generates heat by Joule heat when energized, and is attached to the lid 2. In the present embodiment, three electric resistance heaters 3 are attached to the lid portion 2 and are arranged at equal intervals along the circumferential direction. The electric resistance heater 3 is formed in a U shape having a pair of

end portions

30a and 30b in the present embodiment, and both

end portions

30a and 30b pass through the lid portion 2 and are exposed on the lid portion 2. , And is fixed to the lid portion 2 via the mounting base 32. Metal terminals (not shown) are provided at both

ends

30a and 30b of the electric resistance heater 3, and a heat-resistant lead wire 31 is connected to the terminals. The lead wire 31 connects one end 30 a and the other end 30 b of the adjacent electric resistance heater 3. In addition, each lead wire 31 is connected to a power supply device (not shown), and can be energized to each electric resistance heater 3.

The heating element forming the electric resistance heater 3 can be formed of a metal material such as iron, copper, and stainless steel, or a ceramic material such as silicon carbide and molybdenum disilicide. If the heating element is made of a ceramic material, the amount of heat generated per unit area can be increased, so that the heater can be used at a higher temperature. However, when the heating element is made of a ceramic material, the heater is more easily damaged than when it is made of a metal material. Therefore, in this embodiment, since the heater can be prevented from being damaged by using the protective cover 4 described below, the heater is safely heated to a higher temperature by using a ceramic material for the heating element. Became possible.

The protective cover 4 is attached to the lid 2 so as to surround the electric resistance heater 3 as shown in FIGS. 1 and 6. Since the electric resistance heating heater 3 is easily broken when it is made of ceramic, for example, the protective cover 4 surrounds and protects the electric resistance heating heater 3, so that the ladle heating device 1 is transported or the ladle 10. The electric resistance heating type heater 3 is prevented from colliding with something and being damaged at the time of attachment to the head. In this embodiment, the protective cover 4 has a frame shape, and is disposed so as to surround the electric resistance heating type heater 3. The plurality of vertical frame members 40 extending in the vertical direction and horizontally on the plurality of vertical frame members 40. It is comprised with the crossed horizontal frame material 41 spanned. The electric resistance heater 3 is accommodated in a vertically extending space surrounded by the plurality of vertical frame members 40. The vertical frame member 40 has, for example, a steel rod shape or a pipe shape, and in the present embodiment, three vertical frame members 40 are arranged at equal intervals along the circumferential direction. An upper end portion 40 a of the vertical frame member 40 penetrates the lid portion 2 and is exposed on the lid portion 2, and is fixed to the lid portion 2 via an attachment base 42. The lower end portion 40 b of the vertical frame member 40 extends below the lower end portion of the electric resistance heating heater 3. The horizontal frame member 41 is also, for example, a steel rod shape or a pipe shape. In this embodiment, the horizontal frame member 41 having a ring shape in plan view is fixed to the plurality of vertical frame members 40 by welding or the like in three stages in the vertical direction. Yes. Further, the lowermost horizontal frame member 41 is fixed to the lower end portions 40b of the plurality of vertical frame members 40, and the ladle heating device 1 can stand on its own by the lowermost horizontal frame member 41.

The protective cover 4 surrounding the electric resistance heater 3 needs to be arranged at an appropriate position between the refractory heat insulating material 10B lined in the ladle 10 and the electric resistance heater 3. If it is too close to the electric resistance heating type heater 3 side, the protective cover 4 becomes high temperature due to radiant heat from the electric resistance heating type heater 3 and the strength is lowered. On the other hand, if it is too far from the electric resistance heating type heater 3 side, various shapes are formed. This is because it cannot be used for the ladle 10. Moreover, it is preferable that the protective cover 4 surrounding the electric resistance heating heater 3 has a shape with many openings so as not to block the radiant heat from the electric resistance heating heater 3 to the refractory heat insulating material 10B on the inner surface of the ladle 10. .

Next, a method for heating the inside of the ladle 10 using the ladle heating apparatus 1 having the above-described configuration will be described. First, the lid 2 to which the electric resistance heater 3 is attached is lifted using a hoist or a forklift and placed above the ladle 10, and then the lid 2 is lowered to set the electric resistance heater 3. Set in the ladle 10 and close the upper opening 11 of the ladle 10 with the lid 2. At this time, between the lid 2 and the ladle 10, a heat-resistant (for example, carbon-based) sealing material or a ceramic fiber cushioning material is used to substantially seal between the two. preferable. And the ladle 10 is heated from the inside by energizing the electrical resistance heating type heater 3 from a power supply device (not shown) and making the electrical resistance heating type heater 3 high temperature. In addition, the heating temperature of the ladle 10 can be measured by attaching a thermocouple or the like to the outer peripheral surface of the ladle 10, and by adjusting the voltage applied to the electric resistance heater 3, The heating temperature can be controlled.

According to the ladle heating device 1 having the above-described configuration, the ladle 10 is heated by the electric resistance heating heater 3 attached to the lid portion 2 while closing the upper opening 11 of the ladle 10 with the lid portion 2. Escape to the outside of the ladle 10 can be suppressed. Therefore, since the ladle 10 can be efficiently heated and heated by energizing the electric resistance heater 3, the working environment such as high temperature, noise, and environmental pollution, which is a concern during heating by the burner, is remarkable. Deterioration can also be prevented. Moreover, since it can heat in air | atmosphere, it is not necessary to make the internal space of the ladle 10 into an inert gas atmosphere like the heating by arc discharge.

Table 1 shows the heating temperature of the ladle 10 when the ladle 10 is heated with the ladle heating device 1 of the present embodiment (Example) and when the ladle 10 is heated with a gas burner (Comparative Example). Is the time until the temperature rises to a predetermined temperature (150 ° C., 200 ° C., 250 ° C.) and the amount of energy used. The ladle 10 has an upper end diameter of 750 mm, an upper opening 11 diameter of 610 mm, a lower end diameter of 650 mm, an inner space bottom diameter of 510 mm, a height of 980 mm, and a casing thickness of 16 mm. The total thickness of the lining heat insulating material and refractory material is 70 mm. The electric resistance heater 3 is made of ceramic and has a height of 1200 mm and a thickness of 25 mm. The ladle 10 is heated using three U-shaped electric resistance heaters 3. The amount of power is 37 kWh and the amount of energy is 31835.5 kcal / h. In addition, the gas burner uses city gas, the heat amount is 46 MJ / m ³ , the gas usage amount is 4 m ³ / h, and the energy amount is 43977.1 kcal / h. In addition, the heating temperature of the ladle 10 measured the temperature in the position where the height from the upper end part of the ladle 10 is 450 mm, and the depth from the inner surface of the ladle 10 is 36 mm.

According to Table 1, as in the ladle heating device 1 of the present embodiment, the heating using the electric resistance heating heater 3 takes more time to reach a predetermined heating temperature than the heating using the gas burner. It is confirmed that the time is short and the internal temperature of the ladle 10 can be quickly raised. In addition, when comparing the amount of energy used, heating using the electric resistance heater 3 requires less than half the amount of energy used for heating using the gas burner, and the gas burner is used as the heating temperature increases. It is confirmed that the ratio of the amount of energy used to the heating that has been reduced. Therefore, the ladle heating apparatus 1 of the present embodiment can realize good thermal efficiency and energy saving.

In addition, since the electric resistance heater 3 is surrounded and protected by the protective cover 4, the electric resistance heater 3 is changed to something when the ladle heating device 1 is transported or attached to the ladle 10. It can be prevented from being damaged by hitting.

Moreover, since the heat insulating material 21 is arrange | positioned at the surface on the side which touches the ladle 10 of the cover part 2, at the time of the heating of the ladle 10, heat is effectively confine | sealed in the internal space of the ladle 10 and the ladle 10 is made. It can be heated efficiently.

Also, by using a ceramic heater as the electric resistance heating type heater 3, the amount of heat generated per unit area can be increased, so that the ladle 10 can be heated more efficiently.

As mentioned above, although one embodiment of the present invention was described, the concrete mode of the present invention is not limited to the above-mentioned embodiment. For example, in the above embodiment, the electric resistance heater 3 is U-shaped, but may have various shapes. Moreover, in the said embodiment, although the cover part 2 is equipped with the heat insulating material 21, it does not need to be equipped with the heat insulating material 21. FIG. Moreover, in the said embodiment, although the lowermost frame material 41 of the protective cover 4 adheres to the lower end part 40B of the some vertical frame material 40, the ladle heating apparatus 1 can be made self-supporting, The horizontal frame member 41 is not necessarily fixed to the lower end portions 40B of the plurality of vertical frame members 40, and may be fixed at a position above the lower end portions 40B. Moreover, the shape of the protective cover 4 can also be made into various shapes as long as it has an opening so as not to block the radiant heat from the electric resistance heater 3 to the refractory material on the inner surface of the ladle 10. Moreover, you may make it provide the safety fence which surrounds the electrical resistance heating type heater 3 etc. on the upper surface of the cover part 2, and prevents the contact from the outside.

Further, the ladle heating device 1 may further include a support stand 5 that supports the lid 2 from below and holds the electric resistance heater 3 in a suspended state as shown in FIG. This support stand 5 is for making the ladle heating device 1 stand by itself when not using the ladle 10 when not heating (standby), and is attached to the frame 50 and the frame 50 that can stand independently. And a support member 51 that supports the lid 2 from below. The frame 50 includes a pair of upper and lower horizontal frames 52 in plan view, and a plurality of vertical frames 53 that connect the pair of upper and lower horizontal frames 52. The frame 50 is vertically surrounded by the plurality of vertical frames 53. The protective cover 4 is accommodated in the extending space. The vertical frames 53 are, for example, steel rods or pipes, and in the present embodiment, six vertical frames 53 are arranged at equal intervals along the circumferential direction. The length of the vertical frame 53 is set to be longer than the length of the vertical frame member 40 of the protective cover 4. The horizontal frame 52 is also made of, for example, a steel rod or pipe, and its outer shape is slightly smaller than the outer shape of the lid 2. The support members 51 are fixed to the upper horizontal frame 52, and in this embodiment, three support members 51 are arranged at equal intervals along the circumferential direction. The support member 51 has a shape bent in an L shape in a longitudinal sectional view, and has a vertically oriented guide portion 54 that is curved along the outer peripheral surface of the lid portion 2, and a vertical direction with respect to the guide portion 54. And a side pedestal 55 formed sideways. By placing the lid portion 2 on the pedestal portion 55 of the support stand 5, the ladle heating device 1 can be made independent when not in use (standby) when the ladle 10 is not heated.

DESCRIPTION OF SYMBOLS 1 Ladle heating apparatus 2 Cover part 3 Electric resistance heating type heater 4 Protective cover 5 Support stand 21 Heat insulating material 40 Vertical frame material 41 Horizontal frame material

Claims

A lid for closing the opening of the ladle having an opening at the top;
An electric resistance heating heater attached to the lid and heating the inside of the ladle;
A ladle heating device comprising: a protective cover attached to the lid so as to surround the electric resistance heater.
The protective cover is
A plurality of vertical frame members, which are arranged so as to surround the electric resistance heater, and extend in the vertical direction;
The ladle heating apparatus according to claim 1, wherein the ladle heating device is configured by a plurality of horizontal frame members that are horizontally stretched over the plurality of vertical frame members.
The ladle heating apparatus according to claim 2, wherein the horizontal frame member is bridged to lower ends of the plurality of vertical frame members.
The ladle heating apparatus according to claim 1, further comprising a support stand that supports the lid portion from below and holds the electric resistance heater in a suspended state.
The ladle heating apparatus according to claim 1, wherein a heat insulating material is provided on a surface of the lid portion on a side in contact with the ladle.