JPH0248830B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a metal melting and refining device that is applied to producing steel materials from molten metal lumps and/or iron scraps and/or sponge iron. It is related to.

[Prior art]

A variety of melting equipment are used in steel production. Steel is produced in Siemens Martin furnaces, converters, or electric arc furnaces, depending on the available starting materials and to some extent due to historical factors.

In the European region, Siemens Martin furnaces have been largely replaced by economically operated converters, but one of the disadvantages of converters is their high investment costs. Also, if a Siemens Martin reactor is replaced by a converter, the shed must be rebuilt because the converter does not have the necessary shed room. Furthermore, melting relatively large amounts of iron scrap in converters has presented other difficulties. This problem is discussed, for example, in West German Publication No. 27 29 982.

Arc furnaces are hardly suitable for the use of molten metal ingots. Also, energy costs are high and electrical energy is not always available in the desired amount.

[Problem that the invention seeks to solve]

The aim of the invention is to make available a melting device which is unbiased with respect to charge material and energy source and is characterized by low investment costs. The melting equipment can replace Siemens Martin furnaces in existing steel mills and is suitable for processing desired mixtures of scrap iron, sponge iron, solids and molten metal lumps. Furthermore, if a preheating device is used to preheat the material charged into a general melting device,
A guarantee is provided that when the material is charged into the furnace chamber, the first and second nozzles opening into the furnace chamber are protected from mechanical damage in order to be able to operate.

[Means for solving problems]

In order to achieve the above object, the present invention provides a furnace chamber body into which charging material is charged from an upper opening, and a method for preheating the charging material charged into the upper opening of the furnace chamber main body. It is installed in the upper part of the furnace chamber body and is closed to hold and preheat the required amount of charging material, and in its closed state, the high temperature exhaust gas generated during the melting process inside the furnace chamber body passes upward. a preheating device equipped with an iron grate at its bottom that can be opened and closed;
The object of the present invention is to provide a metal melting and refining apparatus comprising driving means for opening and closing the iron grate of the preheating apparatus.

〔Effect of the invention〕

The operating costs of the inventive melting apparatus described above are lower compared to the Siemens-Martin furnace, allowing for faster charging of iron scrap, increasing production per unit time, and reducing energy costs. It is possible to replace Siemens Martin furnaces in existing steel mills with the melting apparatus of the invention at modest investment costs.

Compared to electric arc furnaces, a larger charge of molten metal ingots up to 90% of the charge capacity is possible, lower energy costs, lower investment costs and a simpler method for the production of low carbon steel. The carbon content is reduced. In combination with an arc electrode, the melting device of the invention is rather more flexible in its application. The power supply does not need to reach a peak level and can be limited to an intermediate level. This is because other power sources can be used depending on the power supply.

In comparison with converters, higher scrap iron contents can be used, investment costs are substantially reduced and better utilization of electrical power is possible.
Additionally, a continuous process is possible, allowing for analysis during the process, and by varying process conditions and adding fine powder solids through the nozzle, the desired final product can be obtained. Also, alloy steels of desired compositions can be produced more easily than in converters or arc furnaces.

In the melting and refining apparatus of the present invention, any mixture of solid metal lumps, molten metal lumps, iron scraps, and sponge iron is suitable as the charging material.
In addition, oil, coal, gas,
Or electric power may be used. If the melting equipment is configured without electrodes, the required height of the shed is lower and the equipment is easier to replace, repair and repair.
can be managed. Furthermore, due to the low investment costs, the existing melting equipment can be easily retrofitted with other melting equipment and can also be adapted to changing conditions of the charge material or energy supply. In addition, when a preheating device for charging material is provided in the above-mentioned melting and refining equipment, iron grates forming the bottom of the preheating device are provided at several locations opening from the center of the furnace. Lump of charge material during operation,
In particular, the risk of damaging the nozzle due to falling large chunks of iron scrap, which is posed by the shape of the furnace chamber, is eliminated. This allows for control of the operation of the furnace and ensures that no lumps of iron scrap fall into the central area of the furnace and damage the nozzle.

〔Example〕

A metal melting apparatus 1 to which the present invention is applied shown in FIGS.
This apparatus 1 is for producing steel materials from iron scraps and/or sponge iron, and is configured as a circular furnace. The furnace chamber main body 2 is configured as follows. The ratio of the inner diameter d and height h of this furnace chamber is
It is 0.8-2.5, preferably 1.0-2.0. The lower part of this furnace chamber main body is made of brick, and the upper wall is formed by a water-cooled chamber in a known manner, and this water-cooled chamber is protected by a heat-resistant material 5 inside the furnace. . For example, when compared with a conventional arc furnace equipped with a water cooling chamber as described in West German Publication No. 2659827,
In the present case, the brickwork is stacked slightly higher, due to the provision of nozzles through which the oxygen-containing gas and fuel are jetted. In this case, there are two types of nozzles: the first nozzle 6 is for blowing out gas containing oxygen, and is installed at the bottom of the furnace chamber body 2 with a horizontal or slightly downwardly inclined axis; They are each provided inside a bench 7 made of a heat-resistant material. These nozzles 6 discharge oxygen-containing gas into the furnace chamber at a height of approximately 10 to 20 cm above the melting surface 9, that is, the hearth 12 formed by the heat-resistant lining 11. These nozzles include, for example, in a known manner a central passage for passing oxygen or an oxygen-containing gas, and at least two annular passages concentrically surrounding this central passage for passing a protective fluid such as propane, petroleum, etc. Consists of two concentric tubes. The passages mentioned above are connected by pipelines to an oxygen supply source and a protective fluid supply source, not shown, respectively. A nozzle bench 7 is provided on each side of the tap opening 10, within which the nozzle 6 is supported substantially radially inward. This arrangement not only ensures thorough mixing of the melt, but also creates a high temperature in front of the tap spout 10, which prevents tap spout scaling outward from the furnace.

The second nozzle 8 is configured as a burner and is supported by the side wall of the furnace chamber body 2 above the melting surface 9 indicated by the dashed line. These nozzles 8 are supplied with fuel, such as petroleum or coal powder and oxygen-containing gas or oxygen, from a suitable fuel source through connecting pipelines. If oxygen is supplied in excess, reburning of the combustible gases rising in the furnace chamber can be achieved by these nozzles. Additionally, additional material may be ejected through the first and/or second nozzles if necessary. The gutter of the furnace chamber is indicated by 13, and the arc electrode inserted through the lid is indicated by 14.

The metal melting and refining apparatus 21 of the present invention shown in FIG.
The fuel is ejected below the melting surface shown by 3, and the second nozzle 25 ejects the fuel above the melting surface. Note that the second nozzle is connected to the furnace chamber main body 2.
It is supported at four points around it through the peripheral wall of No. 2. On the other hand, the bottom of the furnace chamber main body 22 is made of brick and covered with a refractory material, and the upper recessed wall 26 is made up of a fan-shaped cooling box.

Above the furnace chamber main body 22 is a preheating device 2 for preheating the material charged into the melting and refining device.
7 is provided, in this case a preheating device 2
7 is an iron scrap preheating device equipped with a hood 28 connected to a chimney 29 for exhaust gas. Note that the preheating device 27 has a volume required for completely charging the furnace chamber.

The floor of the iron scrap preheating device 27 is formed by an iron grate consisting of two parts 30, 31, which are of identical construction and are inwardly and outwardly insulated by hydraulic cylinders 32. will be moved. Iron scrap charged into the furnace chamber is held inside each iron grate and preheated to a desired temperature by high temperature exhaust gas generated during the melting process inside the furnace chamber. By retracting the iron grate parts 30 and 31 by the action of the hydraulic cylinder 32, the temperature is 80℃~1000℃.
Iron scrap preheated to ℃ is charged into the furnace chamber.
This saves the energy required for preheating the iron scrap. Thus, the iron grate sections 30, 31
When they are pulled apart, a gap is created in the center, which widens, and the iron scraps fall in a controlled manner from the preheater into the furnace chamber. The size of the opening formed by the gap can be controlled, and the controlled charging of iron scrap into the furnace chamber reliably prevents mechanical damage to the two nozzles 25. . For this purpose, the first nozzle 24 is embedded in a bench 33 made of refractory material in the floor of the furnace chamber 22, thereby ensuring a longer service life. This bench extends to the center of the furnace chamber 22, which is configured as a circular furnace. By the way, it is advantageous to bulge the furnace chamber outward at the position of the first nozzle 24 so that a bench of sufficient length in the axial direction of the first nozzle 24, that is, a brick wall can be provided in that part. It has been proven that. Note that one nozzle bench 33 is formed on each side of the tap opening 10. (See FIG. 4) The chimney hood 28 can be pulled out laterally or pulled upwards onto the furnace platform for charging material. The exhaust gas chimney is designed as a bench chimney, with which the exhaust gases are discharged from the furnace chamber through a preheating device for scrap iron. A heat exchanger can be provided in the exhaust gas stack, which heat exchanger is used to preheat the gas, in particular the combustion air, required for the process in the melting chamber.

As shown in the cross-sectional view of FIG. 3 shown in FIGS.
It has a plurality of parallel lattice bars 34 on which are supported. The frame 35 consists of an upper front cross beam 36, a lower rear cross beam 37, and two cross beams 38 and 39 when viewed from the center of the furnace. A pair of wheels 44 are attached to each point 40 to 43 of the cross beam, and each of these wheels 44 is connected to the rail 4.
5,46. The hydraulic cylinder 32 is provided with one end connected to the iron scrap preheating device 27 and the other end connected to the frame 35,
By this hydraulic cylinder 32, the rails 45, 4
The frame body is moved along 6. In this case, each rail is designed as an I-beam, so that the forces exerted by the charge material via the iron bars on the frame 35 are received by the rails 45,46.

The iron lattice bars 34 fixed to the frame body 35 each have a trapezoidal cross section that tapers downward, and have passages for cooling water. In this embodiment, these bars are hollow and reinforced internally by longitudinal webs 47. The web 47 extends the length of the grate bar and does not extend to each end of the grate. As a result, two wires are connected to each other at the end of the iron grate extending toward the inside of the furnace.
Two passages 48, 49 are formed. At the other end of the iron grate, cooling water is supplied to one passage and discharged from the other passage. In addition, as shown in one iron grid bar in FIG. 5, two longitudinal webs 4
7a and 47b may be provided. In this case, the cooling medium is supplied through the central passage and returns through the two outer passages. Thus, the iron grate is cooled uniformly on both sides, with the greatest cooling occurring in the area below the section experiencing the highest temperatures.

In order to prevent the hot gas rising from the melting chamber from escaping between the iron grate bars, the iron grate portions 30,3
1 penetrates the wall of the preheating device, a side plate is provided, which closes the gap between the solid iron grate bars. Such a side plate is attached, for example, to the water-cooled upper end region 50 of the furnace chamber and has a trapezoidal upwardly narrowing cross section which engages the gap between the iron bars.

In FIG. 6, another arrangement of the iron grate is shown schematically, in which four grate sections 51-54 are branched at an angle of 90° to each other and are connected by pins 55-58. Can be moved axially.

Suitable charge materials are in particular scrap iron and/or sponge iron, and the preheating device 27, in particular the grate sections 30, 31, should be configured according to the charge material used.

In the embodiments described above, the iron grate section is configured to be movable in the longitudinal direction, but the iron grate section can also be opened and closed by tilting the iron grate section. In this case, the grate sections do not have to be aligned with each other; for example, they can be tilted slightly downwards towards the center of the melting device. It is also advantageous with respect to the convertibility of the melting and refining device if the entire preheating device can be moved horizontally to open the furnace chamber.

[Brief explanation of drawings]

FIG. 1 shows a longitudinal section of an embodiment of a melting device to which the present invention is applied, and FIG. 2 shows a cross-sectional view of the same. FIG. 3 shows a longitudinal section of an embodiment of the melting device according to the present invention, FIG. 4 is a partially cutaway representation of the cross section taken along the line --- in FIG. 3, and FIG. The iron grid is shown in cross section, and FIG. 6 schematically shows the arrangement of four iron grids which can be displaced relative to each other. Explanation of symbols 2, 22...Furnace chamber body, 10...
Tap port, 6, 24... 1st nozzle, 8, 25...
...Second nozzle, 27...Preheating device, 30,3
1... Closing means (iron grate).

Claims (1)

[Scope of Claims] 1. A furnace chamber body into which charging material is charged from the upper opening, and an upper part of the furnace chamber body for preheating the charging material charged into the upper opening of the furnace chamber main body. An openable and closable iron grate is provided in the furnace chamber and is closed to hold and preheat the required amount of charge material, and in its closed state allows the hot exhaust gas generated during the melting process inside the furnace chamber body to pass upwards. A metal melting and refining apparatus comprising a preheating device provided at the bottom thereof and a driving means for opening and closing the iron grate of the preheating device. 2. Metal melting according to claim 1, characterized in that the iron grate of the preheating device is constituted by a plurality of iron grate sections that are joined to each other at the center of the preheating device in the closed state. Purification equipment. 3. The metal melting and refining apparatus according to claim 2, wherein the iron grate portion is configured to be actively cooled by a cooling medium flowing therein. 4. The iron grates of the preheating device are joined to each other,
Claim 1, characterized in that it is constituted by two opposing lattice portions that are separated.
The metal melting and refining equipment described in . 5. Metal melting and refining according to claim 1, characterized in that the iron grate of the preheating device is constituted by four 90° branched iron grate sections that can move backward or forward in the radial direction, respectively. Device. 6. The metal melting and refining apparatus according to claim 4 or 5, wherein each of the iron grid portions is constituted by a plurality of iron grid bars each having a cooling medium passage therein. 7. The metal melting and refining apparatus according to claim 6, wherein each of the iron lattice bars has a trapezoidal or triangular cross section that tapers downward. 8. The metal melting and refining apparatus according to claim 6, wherein each of the iron lattice bars is a hollow bar having a cooling medium passage therein and reinforced by a web. 9. The metal melting and refining device according to claim 1, wherein the preheating device is provided with an exhaust gas chimney formed as a bench lily chimney in the upper part thereof. 10. The metal melting and refining apparatus according to claim 1, wherein at least one burner for discharging fuel gas is provided in the upper region of the furnace chamber body. 11. According to claim 1 or 10, there is provided at least one nozzle for discharging oxygen or oxygen-containing gas into the molten metal in the bottom region of the furnace chamber body. The metal melting and refining equipment described. 12. The metal melting and refining device according to claim 1, wherein the entire preheating device is provided so as to be movable in the lateral direction. 13 The furnace chamber body has a ratio of its inner diameter d to height h.
The metal melting and refining apparatus according to claim 1, characterized in that it is configured as a furnace chamber body having a round hearth with a diameter of 0.8 to 2.5 (preferably 1.0 to 2.0). 14. The metal melting and refining apparatus according to claim 1, wherein the furnace chamber body is configured as a reactor for melting and refining charged materials such as scrap or sponge iron.