JP3546843B2 - Arc electric furnace for steelmaking - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to an arc light type electric furnace for steelmaking, in which a material to be melted as a cold material is melted and refined using heat of an electric arc (or arc light) generated between electrodes.
[0002]
[Prior art]
The arc type electric furnace includes an indirect type arc furnace and a direct type arc furnace. The indirect arc furnace is used for melting and refining a material to be melted by radiant heat of arc light generated between upper electrodes, and includes a radiation arc electric furnace such as a stassano furnace or a Lenner felt furnace. A direct arc furnace is one in which the material to be melted is melted and refined by the heat of the arc light generated between the electrode and the material to be melted, and an electric current flows from one electrode through the steel slag, the molten steel, and the steel slag to the other. An arc-type electric furnace, such as an Aeru-type electric furnace, which melts and scours by the heat of the arc light generated when flowing to the electrodes, and the electric current flowing from the upper electrode passes through steel slag and molten steel to enter the lower hearth electrode. There is a hearth-type arc light electric furnace such as an electric furnace. Such an arc-type electric furnace is capable of easily adjusting the temperature of molten steel because of obtaining heat at a high temperature (1800 to 1900 ° C.), having high heat efficiency, and changing the atmosphere in the furnace to either oxidizing or reducing. From the advantages of easy adjustment, removal of impurity elements such as P and S in molten steel, less restrictions on raw materials, small installation area of furnace, and low equipment cost, ordinary steel It is widely used from to steel alloy manufacturing.
[0003]
The furnace body structure of the arc-light type electric furnace is such that refractory bricks such as chrome or magnesia brick, magnesia clinker, dolomite clinker, etc. A water-cooled panel having a structure with a built-in cooling water flow passage is lined with an upper surface on the furnace wall side above the irregular-shaped refractory. On the side of the furnace shell, there is a tap hole with a door and a tap hole. At the top of the furnace, there are many kinds of materials to be melted such as cold materials such as scrap iron and pig iron, hot metal or molten steel, solvents such as lime and fluorite, and reducing agents such as coke and ferrosilicon. A charging port and a furnace lid for opening and closing the charging port are provided. In addition to the many types of auxiliary equipment required for operating the furnace, such as the furnace tilting device and the electrode lifting and lowering device, oxygen or oxygen and fuel are simultaneously exposed to shorten melting time and improve productivity. An oxygen lance or an oxygen burner for injecting the molten material or the steel bath surface is provided above the furnace wall.
After charging the material to be melted, such as cold material or solvent, into the arc-type electric furnace with such a structure from the charging inlet, an electric current is passed through the electrodes charged in the furnace to generate an electric arc with the material to be melted. Then, the material to be melted is melted by the heat of the arc and the heat of oxidation reaction between the oxygen injected into the furnace and the carbon and silicon contained in the melted material and the injected or injected fuel. A large amount of CO gas generated from the steel bath during melting of the material to be melted is partially burned in the furnace by oxygen in the air entering the furnace, and the heat of combustion accelerates the melting of the material to be melted. The furnace temperature is raised, but the rest is discharged from the furnace. The exhausted CO gas is completely burnt in the combustion tower of the CO gas draft recovery device and turned into exhaust gas because of the problem of deteriorating the working environment and causing pollution problems. The heat of the exhaust gas is partially used for preheating the material to be melted, but in this method, much of the heat of combustion of the CO gas is taken away by the air entering the furnace or the cooling water of the combustion tower, so that a large heat loss occurs. . Therefore, a method of installing a secondary combustion oxygen lance for burning CO gas in the furnace, burning the CO gas as much as possible in the furnace with oxygen ejected from the lance, and increasing heat recovery in the furnace has been adopted in recent years. It is becoming.
[0004]
[Problems to be solved by the invention]
However, the conventional secondary combustion lance is used by inserting it into the through hole of the water-cooled panel from the upper part of the furnace shell, but in order to efficiently burn the CO gas generated from the steel bath, it is necessary to use the furnace. Since it is better to inject oxygen as uniformly as possible from around the body, a plurality of furnaces are often installed so as to divide the periphery of the furnace substantially evenly. The arc-light type electric furnace provided with the secondary combustion oxygen lance in this way burns CO gas generated in the furnace in the furnace, and the combustion heat is effectively used as heat for melting the material to be melted. Can be evaluated. However, the number of secondary combustion oxygen lances mounted on the furnace wall is usually four, and at most about eight. Attaching a larger number of secondary combustion oxygen lances to the furnace wall will reduce the holding strength of the furnace body, making it difficult to withstand high-temperature heat and tilting operation of the furnace body, thus shortening the life of the furnace body. And the cost of repairing the furnace body increased. Although such a problem can be avoided by installing a small number of secondary combustion oxygen lances, in order to sufficiently combust the generated CO gas and reuse it for the heat of melting of the material to be melted, one secondary combustion oxygen lance is required. A large amount of oxygen gas must be ejected vigorously from the oxygen lance, which causes a problem that the supply of oxygen gas is partially interrupted, causing uneven heating unevenness called cold spots or hot spots on the material to be melted. There was a problem that the phenomenon of delay of the rise temperature appears.
[0005]
The present invention has been made to solve the above-described problems, and uniformly increases the temperature to the melting temperature of the material to be melted and accelerates without lowering the furnace strength, thereby shortening the melting and refining time. To provide an arc light type electric furnace.
[0006]
[Means for Solving the Problems]
The present invention has achieved the object, and the gist of the present invention is that a refractory layer is lined on a lower surface of a hearth side of a furnace shell of an arc light type electric furnace, and further, a refractory layer is formed on a furnace wall side of the furnace shell. An oxygen gas supply chamber having a built-in refrigerant flow furnace on the side and connecting an oxygen gas supply pipe penetrating the furnace wall steel shell and having a large number of oxygen gas outlets perforated in the furnace circumferential direction directed toward the material to be melted is provided. This is a steelmaking arc-type electric furnace constructed by lining a refrigerant distribution panel provided at an arbitrary position.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the arc-type electric furnace for steelmaking of the present invention will be described in detail with reference to the drawings.
FIGS. 1 and 2 show an embodiment of an arc electric furnace for steelmaking of the present invention. FIG. 1 is a longitudinal sectional view of the present invention, and FIG. 2 is a sectional view taken along line XX of FIG. In FIG. 1, reference numeral 1 denotes a furnace shell of an arc electric furnace. The furnace shell 1 is used to support the furnace body of an arc-light type electric furnace. The furnace wall side upper surface A is formed into a cylindrical shape by welding or tacking a thick steel plate such as ordinary steel or special steel. The lower surface B on the hearth side is formed into a dish shape and, if necessary, is a unitary steel shell using reinforcing materials at various places to prevent deformation due to high temperature. The furnace body is generally circular, but may have any shape such as an elliptical shape or a rectangular shape. 2 is a refractory layer. The refractory layer 2 is formed by stacking various refractory bricks such as chrome bricks and magnesia bricks on the hearth side lower surface B of the furnace shell 1 or disposing an irregular refractory material such as magnesia clinker and dolomite on the refractory bricks. It is applied to the heat-resistant structure of the refractory lining by hardening it into a shape. Numeral 3 is a refrigerant distribution panel which is provided so that an upper surface A of the furnace shell 1 on the furnace wall side is stuck in the furnace. As shown in the cross-sectional view of each part in FIG. 3, the refrigerant distribution panel 3 is provided with a distribution guide wall 5 (shown by a dotted line) inside a panel box 4 having an arbitrary shape having a space inside, for example, a rectangular cross-sectional shape. In this structure, a refrigerant such as water or a low-temperature gas meanders so as to cool the entire box and has a built-in refrigerant flow passage 6 flowing in the same direction (internal perspective view in FIG. A). Reference numeral 7 denotes a refrigerant inlet, which is connected to a refrigerant supply device (not shown), and reference numeral 8 denotes a refrigerant outlet, which is connected to a refrigerant supply source recovery device (not shown). Further, the refrigerant distribution panel 3 is provided with an oxygen gas dispersion supply chamber 9 at an arbitrary position. FIG. 3 shows an embodiment (FIGS. A, b, and c) in which an oxygen gas dispersion supply chamber 9 is provided on the lower surface B side of the hearth side of the refrigerant distribution panel 3. An oxygen gas supply pipe 10 connected to an oxygen gas supply source (not shown) penetrates through the furnace shell 1 and connects to the oxygen gas dispersion supply chamber 9. A large number of oxygen gas outlets 11 are formed in the furnace circumferential direction (FIG. D). FIG. 2 shows an example in which a large number of oxygen gas outlets 11 are formed in the furnace circumferential direction. Reference numeral 12 denotes a tapping outlet, and reference numeral 13 denotes a tapping outlet. That is, the refrigerant distribution panel 3 according to the present invention has a structure in which the refrigerant distribution passage 6 is built in, and the oxygen distribution and supply chamber 9 for introducing and ejecting oxygen gas from an arbitrary position is provided at an arbitrary position. I have.
[0008]
In FIG. 1, reference numeral 14 denotes an electrode. The electrode 14 is supported by a vertically movable electrode gripper (not shown) that moves up and down as the material to be melted advances and conducts current, and the material to be melted and the electrode 14 The material to be melted is melted and refined by utilizing the high temperature of the arc light heat while generating arc light between. Reference numeral 15 denotes a furnace lid, which has a different structure depending on the charging method of the material to be melted and the structure of the furnace body. Is often used. Further, the furnace lid 15 is provided with a loading opening for the electrode 14, and since heat resistance is required, a refractory brick is lined or a water-cooled structure is constructed.
[0009]
The arc-type electric furnace for steelmaking of the present invention constructed as described above uses a cold material such as scrap iron and pig iron, a material to be melted which is usually used such as quick lime and coke in addition to hot metal and molten steel, and a furnace top. Of the material to be melted (not shown). When the charging of the material to be melted is completed, the furnace cover 15 is put on, the electrode 14 is lowered and charged into the furnace. Then, an arc is generated while gradually increasing the voltage and current, and the material to be melted is heated by the arc heat. Dissolve and scour. During the melting and refining, the oxygen gas outlet 11 provided in the refrigerant distribution panel 3 of the present invention while blowing oxygen gas into the steel bath from a consumable oxygen pipe (not shown) or a water-cooled oxygen lance (not shown). Oxygen gas into the furnace. Oxygen gas blown into the steel bath from a consumable oxygen pipe or a water-cooled oxygen lance burns silicon and carbon contained in the material to be melted and coke and other fuels blown simultaneously with oxygen into the furnace. To promote the melting of the material to be melted, but at the same time generate a large amount of CO gas from the steel bath. The oxygen gas blown into the furnace also from the oxygen gas ejection port 11 provided in the refrigerant distribution panel 3 of the present invention is supplied from the oxygen gas supply source to the oxygen gas dispersion supply chamber 9 via the oxygen gas supply pipe 10. After the gas is once stored and adjusted to a uniform gas pressure and flow rate, as shown in FIG. 2, CO gas generated from the steel bath is discharged from a large number of oxygen gas blowout ports 11 formed in the furnace inner circumferential direction. Burn gas. Since most of the combustion heat is used as heat for accelerating the melting of the material to be melted, the CO gas draft recovery device may also have a low capacity, and has the effect of significantly reducing the possibility of deteriorating the work environment and causing pollution problems. . At the end of refining, steel slag containing harmful oxidizing slag (slag) is scraped out from the slag port 13 and then a carbonized material is added to adjust the amount of C in the molten steel, or to use ferrosilicon or ferromanganese. After completion of the deoxidation reaction accelerating work by adding lime or the like, slag making work is performed by adding quick lime or fluorite, and molten steel is taken out from the tap hole 12 to complete a series of work.
[0010]
The melting and refining operation as described above is an example of the operation in the arc-type electric furnace for steelmaking of the present invention, and it goes without saying that the melting and refining operation of any operation can be used.
[0011]
【The invention's effect】
According to the arc light type electric furnace for steelmaking of the present invention as described above, the secondary combustion rate of CO gas generated from, for example, a 100-ton electric furnace is an average value of CO ₂ / (CO + CO ₂ ), which is the conventional value (4). (The use of the secondary combustion lance of the book) from 40% to 60%. Also, the power consumption rate has been reduced from 400 kwh / t to 370 kwh / t. Further, the material to be melted was melted at a uniform rate without the phenomenon of uneven melting of the material to be melted, and the melting and refining time was reduced from 80 minutes to 74 minutes.
Further, in the arc-type electric furnace for steelmaking of the present invention, even if the oxygen gas outlet is provided on the inner circumference of the furnace, the holding strength of the furnace body does not decrease, and the oxygen gas outlet is provided in the refrigerant distribution panel. Since it is provided in the device, there is a feature that it can be used for a long time without damage by heat.
[Brief description of the drawings]
FIG. 1 shows an embodiment of an arc light electric furnace for steelmaking of the present invention.
FIG. 2 is a sectional view taken along line XX of FIG.
FIG. 3 is an enlarged view of the internal structure of the refrigerant distribution panel according to the present invention, which shows a perspective view of the furnace shell side (FIG. A), a cross-sectional view taken along the line YY (FIG. B), and FIG. A sectional view taken along the line ZZ (FIG. C) and a front view inside the furnace (FIG. D) are shown.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Furnace shell 2 Refractory layer 3 Refrigerant distribution panel 4 Panel box 5 Distribution guide wall 6 Refrigerant flow passage 7 Refrigerant inlet 8 Refrigerant outlet 9 Oxygen gas dispersion supply chamber 10 Oxygen gas supply pipe 11 Oxygen gas outlet 12 Outlet Steel port 13 Slag port 14 Electrode 15 Furnace wall A Upper surface on furnace wall side B Lower surface on furnace wall side

Claims (1)

The refractory layer (2) is lined on the lower surface (B) of the hearth shell (1) of the arc light type electric furnace, and the upper surface (A) of the furnace shell (1) on the furnace wall side. And an oxygen gas supply pipe (10) penetrating through the furnace shell (1) and connected to the furnace shell (1), and an oxygen gas outlet (11) directed toward the material to be melted is provided around the furnace. An arc-type electric furnace for steelmaking, characterized in that a refrigerant distribution panel (3) in which a large number of oxygen gas dispersion supply chambers (9) perforated in the direction are provided at optional positions.

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