JP2002250592A - Heater at discharge opening of furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heater at the discharge opening of a furnace exhibiting excellent corrosion resistance through which any kind of object to be heated can be discharged stably. SOLUTION: The heater at the discharge opening of a furnace comprises a furnace body 1 into which the object 5 to be heated is thrown in, discharge openings 7 and 17 for discharging the object 5 heated in the furnace body 1, heating members 13 and 23 exposed inward on the entire or partial circumference of the discharge openings 7 and 17, and induction heating means 15 and 25 for heating the heating members 13 and 23 wherein the heating members 13 and 23 are formed of ceramics containing 50% by mass of zirconium boronate (ZrB2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace outlet heating apparatus, and more particularly to a furnace outlet heating apparatus which is excellent in corrosion resistance and can discharge stably regardless of the type of an object to be heated.

[0002]

2. Description of the Related Art In recent years, gasification and melting furnaces have attracted attention because of energy saving and environmental measures against dioxins and the like. Also,
The demand for a single melting furnace is increasing because it can render the incineration ash discharged from the incinerator harmless. Since waste such as incinerated ash is generally melted at a high temperature of 1300 ° C to 1500 ° C, dioxin in the ash is decomposed at a high temperature, and harmful metals are dissolved in glass to make them harmless. The heating means of the melting furnace main body is a gasification melting furnace for burning gasified gas, and a single melting furnace is for burning gas or heavy oil or electric heating (plasma, resistance, arc, etc.).

[0003]

The slag outlets of the melting furnace are all remote from the melting furnace body. Also,
Generally, the temperature decreases because of facing the slag bath, and slag tends to stick at the outlet. If the slag adheres, the discharge of the slag is hindered, which hinders continuous operation, and in the worst case, the operation has to be stopped. Further, there is a problem that the slag is solidified in a lower part of the discharge nozzle in the form of a slag, and the slag must be removed when the slag is stopped.

[0004] To solve such a problem, a gas or heavy oil burner is conventionally used to locally heat the vicinity of the discharge nozzle to prevent sticking. However, this method requires the use of a separate fuel, and operation control is troublesome. In addition, since combustion gas is generated, the capacity of the exhaust gas treatment device is increased.

[0005] On the other hand, Japanese Patent Application Laid-Open No. 8-327042 proposes that an induction coil be installed around a furnace material (non-conductive material) at a slag outlet, assuming that the solidified material is a metal. . Also, Japanese Patent Application Laid-Open No. 7-127826 proposes a method in which a coil is arranged around a nozzle (non-conductive) at an outlet of a molten metal to perform induction heating.

However, when the amount of metal components in the melt is small, there is a problem that induction heating does not work.
Japanese Patent Application Laid-Open No. 8-61645 specifies that the downflow nozzle has conductivity, but also includes the furnace bottom electrode and the downflow nozzle control means at the same time. Was limited. In addition, there were no durable, conductive materials that could actually be used in commercial scale plants.

[0007] In addition, even in a melting furnace of iron or non-ferrous metal or a glass kiln, there is a problem in that the temperature of the outlet of the melt decreases, so that the viscosity increases and the outflow of the melt stops. Further, there is a problem that a target product cannot be obtained due to a decrease in quality or a change in quality due to a decrease in temperature or stagnation. For this reason, a method of heating with a burner or the like has been adopted.

The present invention has been made in view of such conventional problems, and has as its object to provide a furnace outlet heating apparatus which is excellent in corrosion resistance and can stably discharge regardless of the type of an object to be heated. And

[0009]

According to the present invention (claim 1), a furnace body into which an object to be heated is charged, and the object to be heated which has been subjected to heat treatment in the furnace body, are provided in the furnace body. A discharge port, a heating member exposed inward around the entire circumference or a part of the discharge port, and induction heating means for heating the heating member, wherein the heating member is zirconium boride. (ZrB2) is formed of ceramics containing 50% or more by mass.

The furnace body includes a furnace for melting at a high temperature, such as a waste melting furnace such as a gasification melting furnace, and a melting furnace for melting metal or glass. The heating method of the furnace is not limited, such as gas combustion, heavy oil combustion, electric heating (plasma, resistance heating, arc, induction heating, etc.). An object to be heated is a material to be melted or a material to be melted which is put into a waste melting furnace or the like. Ceramics containing at least 50% by mass zirconium boride (ZrB2) have conductivity and can be induction heated by induction heating means. Also, it has excellent corrosion resistance. The shape of the outlet may be vertical or sloped, and it may be applied in the form of a pipe or a gutter. Furthermore, it is not affected by the device disposed at the end of the outlet.

Further, the present invention (claim 2) is characterized in that the heating member is provided with a plurality of heating elements made of the ceramics at predetermined intervals.

[0012] The heat generating element can also constitute a heat generating member as an integral body. However, when the heating element is formed as an integral body, if the heating element is damaged for any reason, there is a possibility that an induced current does not flow and no heat is generated. For this reason, a plurality of heating elements are arranged at predetermined intervals to form a heating member. When a plurality of heating elements are formed, it is assumed that the induced current flows in each of the heating elements while forming a loop.

Thus, even if a part of the heating element is damaged, the effect can be stopped at that part and the heat generation can be continued. In addition, in the case of a one-piece structure, when the size is large, the production is difficult and the production cost is high,
The division makes production easy and inexpensive.

Further, the present invention (claim 3) is characterized in that an insulating member is provided between the heating elements.

By disposing the insulating member, it becomes difficult for the induced current to interfere between the heating elements.

[0016]

Embodiments of the present invention will be described below. FIG. 1 shows a cross-sectional view of the first embodiment of the present invention. This figure considers a gasification and melting furnace. However, the present invention is applicable to other than gasification and melting furnaces. In FIG. 1, waste is melted in a melting furnace 1. The bottom 3 in the melting furnace 1 is formed with a slope, and the molten slag 5 flows down the slope, passes through the slag discharge port 7, and falls into the slag device 9. The slag discharge port 7 is disposed vertically below the melting furnace 1 in a cylindrical shape. The melting furnace 1 is formed in a U shape, and the exhaust gas 11 generated in the melting furnace 1 flows to downstream equipment along the U shape. A heating member 13 is exposed on the inner periphery of the slag discharge port 7, and an induction coil 15 is arranged around the heating member.

FIG. 2 shows a detailed structural sectional view of the heat generating member 13. In FIG. 2, trapezoidal heating elements 31 are circumferentially arranged at equal intervals, and an insulating member 33 is interposed between the heating elements 31. Heating element 31 and insulating member 33
A heat insulating material 35 is mounted on the outer periphery of the device, and an outer furnace body 37 is further mounted on the outer periphery thereof. The outer periphery of the outer furnace body 37 is in contact with the inside of the induction coil 15.

Next, the operation of the first embodiment of the present invention will be described. The heating member 13 includes zirconium boride (ZrB2)
At least 50% by mass. Preferably, zirconium boride (ZrB2) is contained in an amount of 80% or more, more preferably 90% or more. As such zirconium boride, a sintered body is preferable, but castable may be used in combination.
The heat generating member 13 has conductivity, and the material itself generates heat by induction heating, so that the molten slag 5 flowing inside can be heated. Here, the temperature of the slag discharge port 7 tends to decrease because the lower surface of the slag discharge port 7 faces the slag device 9. However, the heating member 13 can be heated by appropriately operating the induction coil 15. For this reason, the molten slag 5 is re-melted and can be easily dropped. Therefore,
The presence or absence of the slag device 9 has no effect on the present invention.

It is not necessary to constantly heat the heat generating member 13, and it is not necessary to heat the molten slag 5 when the molten slag 5 is flowing normally. The heating member 13 is heated when there is a problem in the continuation of operation due to the molten slag 5 being fixed little by little over a long period of time, or the melting point being changed due to a change in the components of the molten slag 5, and the molten slag 5 being fixed. May be removed.

If the heating element 31 is damaged for some reason, there is a possibility that the induced current does not flow and no heat is generated. For this reason, as shown in FIG. 2, a plurality of heating elements 31 are arranged at predetermined intervals to form the heating member 13. When a plurality of heating elements 13 are formed, each heating element 13
It is presumed that the induced current flows in each of the loops. Thus, even if a part of the heating element 13 is damaged, its influence can be stopped at that part and the heat generation can be continued.

The optimal range of the size of the heating element 31 varies depending on the frequency of the induced current, the specific resistance of the material, the relative magnetic permeability of the material, and the like. With 100% zirconium boride, 30 ~
A square of 50 mm and a diameter of about 30 to 50 mm are appropriate. If the size is too small, the induced current interferes and does not flow well, so that heat cannot be generated. Conversely, if the size is too large, the divided effect cannot be obtained.

Assuming that the size of the heating element 31 is D, where D is the trapezoidal shape, based on the penetration depth δ (mm), which indicates the depth to which the induced current flows from the surface, D> 5δ
Is set as one standard. Preferably, D> 10
δ.

However, the penetration depth δ (mm) is the specific resistance ρ
(Ω · cm), relative magnetic permeability (ZrB2 is a non-magnetic material is 1), and f is given by Formula 1 by the frequency (Hz) of the induced current.

[0024]

Δ = 5.03 × 10 ⁴ × (ρ / μ / f) ^0.5

The number of the heating elements 31 is at least two.
The number is preferably 6 or more, more preferably 12 or more. The sectional shape of the divided heating element 31 is preferably as close to a circle as possible, but a trapezoidal shape close to a square allows the heating element 31 to be assembled with a protruding structure, which facilitates positioning and manufacturing when forming a nozzle. There are advantages such as becoming.

As the insulating member 33, a silicon carbide refractory, a zirconia refractory, an alumina refractory, a magnesia refractory or the like can be used. Note that the thickness of the insulating member 33 is preferably 5 to 50 mm. If the thickness is not sufficient, a part of the current flows between the divided heating elements 31, so that it is difficult to generate heat. On the other hand, when the thickness is large, the heating element 31 is small and the amount of heat generation cannot be increased, which is not preferable.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a heat generating member 13, zirconium boride (Z
A pipe of zirconium boride containing 98% of rB2) (trade name of SELABOREX CR, Asahi Glass Co., Ltd.) was used. And the size of the pipe is 100mm in outer diameter, 78mm in inner diameter, 150mm in total length
And When a 30 KW, 3 KHz induction heating power supply was used as a power supply, the temperature was raised to 1400 ° C. in about 4 minutes, and the solidified molten slag 5 in the pipe was melted.

Zirconium boride (ZrB2) has conductivity and is excellent in corrosion resistance to molten slag and molten metal. Table 1 shows the ratio of the amount of erosion between zirconium boride (ZrB2) and molten slag when carbon + SiC, which is generally used as a conductive material, is used for the heat generating member 13.

[0029]

[Table 1]

Table 2 shows the amount of erosion when brought into contact with the molten slag at a high temperature without using the heating member 13 by heating, which is generally used for zirconium boride (ZrB2) and a melting furnace. It shows the ratio of the amount of corrosion resistance to a refractory containing chromium.

[0031]

[Table 2]

In each case, zirconium boride (ZrB2) exhibits excellent corrosion resistance as compared with conventional materials, and can be made practically usable even when incorporated in a long-term used system such as a melting furnace.

Next, a second embodiment of the present invention will be described. The same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 3, the slag discharge port 17 is formed at the inclined end of the bottom 3 in the melting furnace 1, unlike the slag discharge port 7 which is vertically arranged in a cylindrical shape in the first embodiment. . A heating member 23 made of zirconium boride (ZrB2) is provided inside the inclined end.
Are arranged. An induction coil 25 is buried under the heat generating member 23.

Also in this configuration, by heating the heating member 23, the molten slag 5 can be re-melted and dropped. In addition, fluctuations in the attained temperature due to a change in the metal component, which has been a problem in the conventional system for heating the metal component in the melt by induction heating, are eliminated, and the melt can be stably heated.

Further, since a material containing at least 50% of zirconium boride (ZrB2) is used for the heat generating members 13 and 23, the material has conductivity and can perform induction heating.
Because of its excellent corrosion resistance to molten slag and molten metal, induction heating of the melt outlet, which has not been possible so far, has come into practical use on a commercial scale.

In the past, heating was locally performed with a burner to prevent sticking. However, such equipment is not required, and combustion exhaust gas can be reduced, and equipment costs such as gas treatment can be reduced. Can bring.

Further, the temperature control by induction heating requires only control of the output, so that it is easy and easy to automate, and complicated operation such as flame control of a burner as in the prior art is not required. In addition, by performing local heating, problems such as melting and damage of the refractory and cracking due to thermal stress can be avoided. The heating member 2
It is preferable that the heating element 3 is formed by dividing the heating element as in FIG.

[0038]

As described above, according to the present invention, the heating member is made of ceramics containing at least 50% by mass of zirconium boride (ZrB2). Induction heating is possible. Excellent corrosion resistance.

[Brief description of the drawings]

FIG. 1 is a sectional view of a melting furnace according to a first embodiment of the present invention.

FIG. 2 is a detailed cross-sectional view of a heat generating member.

FIG. 3 is a sectional view of a melting furnace according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Melting furnace 3 Melting furnace bottom 5 Melting slag 7, 17 Slag discharge port 9 Slag device 11 Exhaust gas 13, 23 Heating member 15, 25 Induction coil 31 Heating element 33 Insulating member 35 Heat insulating material 37 External furnace body

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroshi Maeno 5-6-1 Umai, Takasago City, Hyogo Prefecture Asahi Glass Co., Ltd. F-term (reference) 3K059 AA08 AB04 AD28 AD34 CD52 CD79 4G001 BA45 BB45 BD07 4K055 BA05 JA01 4K063 AA04 BA13 CA05 CA06 FA33 FA36

Claims (3)

[Claims] 1. A furnace body into which an object to be heated is charged, an outlet through which the object to be heated subjected to heat treatment in the furnace body is discharged from the furnace body, and an entire periphery of the outlet. A heating member exposed partially inward toward the inside; and an induction heating means for heating the heating member, wherein the heating member is formed of ceramics containing 50% or more by mass of zirconium boride (ZrB2). Furnace outlet heating device. 2. The furnace outlet heating device according to claim 1, wherein a plurality of heating elements made of the ceramics are arranged at predetermined intervals on the heating member. 3. The furnace outlet heating device according to claim 2, wherein an insulating member is provided between the heating elements.