JP2004101178A - Melting furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a melting furnace such as a vertical shaft cupola and a blast furnace to reduce the dust discharged out of the system as much as possible. <P>SOLUTION: In the melting furnace such as a vertical shaft cupola and a blast furnace having a belly 4 to surround an upper portion of a hearth 1 having a hot metal hearth 2 and a slag hearth 3 and a shaft 5 thereabove, at least three stages of tuyeres 7 to feed air in the vertical direction are provided on a lower portion of the blast furnace, and the tuyere of the first stage out of the tuyeres 7 is a bottom tuyere located on a bottom of the blast furnace. The inside diameter of the shaft is at least two times the diameter of the hearth, and a large empty tank 25 to settle and collect the dust is formed inside the shaft above the layer of iron ores and cokes formed above the tuyeres 7. <P>COPYRIGHT: (C)2004,JPO

Description

(4) The present invention relates to a melting furnace such as a vertical shaft cupola and a blast furnace for extracting pig iron by melting iron ore.

As a conventional blast furnace melting furnace, as shown in FIG. 5, a hearth 1 in which refractory bricks are laid is formed, and a hot metal bed 2 is provided on the upper part so that molten pig iron is collected, and slag is provided on the upper part. A slag bed 3 to be separated is provided, and a furnace belly 4 formed of refractory brick is provided so as to surround them, and a refractory brick is piled up integrally therewith to form a shaft 5 on the upper part thereof. It is surrounded and protected by 6.

羽 Tubes 7 for sending hot air are opened at the same level in the furnace wall at several tens of places, and are formed so that heat passes through the raceway 8 in the furnace. The high-temperature hot air blown from here becomes a combustion gas passing between the iron ore raw material and the coke (for example, every 25 layers) in the multi-stage layer 9A, reduces the iron ore, dissolves and removes pig iron down. At the same time, gas is collected from the furnace top 10 to the blast furnace gas riser 11. In addition, the slag is structured to be taken out of the system.

The charging of the raw material 9 such as iron ore, coke, limestone and the like is carried to the upper furnace top 10 by the belt conveyor 12 and thrown into the hopper 13. It is replenished up to 15. The furnace temperature is higher in the lower part, and is as high as about 2,000 ° C. near the highest raceway.

16 is a blast furnace support, 17 is a hot blast tube, 18 is a gas ash dust settling device, 19 is a taphole, 20 is a torpedo car for carrying pig iron from there, 21 is a slag exit, 22 is a slag wheel, and 23 is a hot air ring Tube.

FIG. 6A shows the same level furnace bottom temperature distribution in the case of the conventional one-stage tuyere, and FIG. 6B shows the same level furnace bottom in the case of the two-stage tuyere. FIG.

In a conventional blast furnace, a multistage layer of iron ore and coke is clogged inside the shaft, and the air supplied from the tuyere burns coke at the raceway to produce high-temperature carbon monoxide and carbon dioxide at about 2,000 ° C. It becomes a gas mixture with the gas, and is discharged from the furnace top while passing through the upper multi-layer. When passing through the raw material packed bed, the fine powder is suspended and the gas ash dust sedimentation device (dust Catcher).

Therefore, a gas ash dust sedimentation apparatus is indispensable, and its gas cleaning accuracy must be high, so that there is a problem that equipment costs are high.

Therefore, if the raw material contains fine powder, there is also a problem that much of it is suspended in gas as dust and discharged. For this reason, the raw material containing a large amount of fine powder sometimes needs to be processed into sinter or pellet processing.

Also, since the tuyere level is usually one stage, that is, only one stage of the same level of the combustion zone called the raceway formed by the blast temperature and blast humidity from the tuyere, the temperature difference in the furnace bottom height direction However, there was a drawback that the The furnace heat temperature control at the furnace bottom was unstable.

Furthermore, there is a proposal to use two-tiered tuyeres, but they were not well connected to the raceway and did not exhibit the expected effect. Particularly, a sufficiently high temperature was not transmitted to the furnace bottom in some cases.

In view of the above-mentioned problems, the present invention provides a melting furnace that does not emit dust such as fine powder from the furnace as much as possible, and also has a function of a dust catcher inside the shaft.

Therefore, even if it uses fine powder to granular raw material, it provides an innovative melting furnace with less dust discharged from the furnace top, without installing a separate dust catcher or increasing the equipment cost. Is also cheaper. The result is a reduction in the amount of industrial waste dust that is emitted.

In order to solve the above-mentioned object, a melting furnace of the present invention is a melting furnace such as a vertical shaft cupola or a blast furnace having a furnace belly surrounding an upper part of a hearth having a hot metal bed and a slag bed and a shaft on the furnace belly. In the lower part of the furnace, there are provided three or more tuyeres for sending air in the vertical direction, and one of the tuyeres is a bottom tuyere located at the bottom of the furnace. The inner diameter of the shaft is twice or more the diameter of the hearth, and a large empty tank for sedimenting and collecting dust is formed inside the shaft above the layer of iron ore and coke formed above the tuyere. is there.

The surface of the raw material layer is positioned above the tuyere provided at the lower part of the furnace (morning glory) and as much as possible below the shaft, and the inner diameter of the shaft is twice or more the diameter of the hearth, and an empty tank can be formed at the upper part of the shaft. The inside of the shaft is used to reduce the gas velocity of the empty tank which rises as an empty tank, and settle and collect dust in the empty tank. Further, by setting the tuyere level to three or more stages, stable combustion in the vertical direction of the furnace bottom can be obtained.

In addition, the bottom tuyere preferably has a protruding nozzle brick tuyere structure or a porous brick tuyere structure.

ダ ス ト Further, in the present invention, dust is not emitted to the outside of the system, so that a raw material containing a large amount of fine powder is used as it is without sintering or pelleting.

の Since the present invention is configured as described above, it has the following effects.

The temperature difference in the raceway generated by the one-stage tuyere and the two-stage tuyere having the same level as the conventional one or the raceway generated by the upper, middle and lower three-stage tuyere increases in the furnace bottom height direction. Therefore, the molten pig iron or slag decreases while descending to the bottom of the furnace, and solidifies at the bottom of the furnace and cannot be discharged smoothly from the tap hole or the slag port, resulting in a so-called fecal clogging phenomenon. In this case, it becomes a serious problem in the production operation of the furnace.

In the present invention, the three-stage tuyere has three stages of high-temperature raceways, and the one-stage tuyere is a bottom tuyere. As a result, the molten iron or the molten slag does not solidify before reaching the furnace bottom as before, and the production operation of the furnace is greatly stabilized.

In particular, in the case of the three-stage tuyere level, the air blown from the upper and middle tuyeres and the lower tuyeres (bottom tuyeres) depending on the temperature condition of the furnace bottom and the temperature of the molten pig iron and molten slag, respectively ( 1) raising and lowering the temperature, (2) raising and lowering the oxygen enrichment, and (3) raising and lowering the temperature to control the hot uniform hot iron temperature and the molten slag temperature. It becomes possible.

In addition, since it has a configuration in which fine powder and the like are difficult to discharge, there is an advantage that, in addition to fine iron ore, steel dust such as converter dust, electric furnace dust, and oil-containing rolling scale powder can be used. In the case of a raw material having many fine powders, it is possible to omit the work of sinter or pellet processing.

転 Steel dust such as converter dust, electric furnace dust and oil-impregnated rolling scale powder generated as industrial waste in the iron mining industry can also be treated in the blast furnace. The ability to treat various types of dust has a great advantage in resource recycling.

In addition, low-grade shredder waste and shredder dust industrial waste of electric products such as automobiles and refrigerators can be used as recycled resources by using the melting furnace of the present invention. That is, due to the low gas flow rate in the space above the shaft (empty tank), dust particles of the shredder can be prevented from scattering outside the furnace, and the high temperature (1000 ° C.) of the furnace top gasifies metals such as zinc. This high temperature promoted the decomposition of dioxins and PCBs and made it a non-polluting gas.

Embodiments of the present invention will be described with reference to the drawings.

FIG. 3 shows an example of the configuration of the lower part of the shaft (hearth 1 and belly 4) which is the main part of a typical melting furnace according to the present invention.
A melting furnace having a main part shown in FIG. 3 is similar to the melting furnace shown in FIG. 1, in which a hearth 1 is formed by placing a refractory brick, and a hot metal bed 2 in which molten pig iron is accumulated is formed on the hearth 1. The furnace belly 4 is surrounded so that the slag bed 3 is formed. Above the furnace belly 4, there is a shaft 5 having a structure in which refractory bricks are piled up. are doing.

{Circle around (4)} Raw materials 9 such as iron ore, coke, and limestone are charged from a furnace top 10 of a blast furnace by a raw material charging belt conveyor 12. Reference numeral 13 denotes a charging hopper for sequentially charging iron ore, coke, and limestone in accordance with an instruction signal.

The main feature of the present invention is that, at the lower part of the furnace, three or more tuyeres for feeding air in the vertical direction, three tuyeres 7 in FIG. One of the tuyeres is a bottom tuyere located at the bottom of the furnace as shown in FIG. 3, and the inner diameter of the shaft is twice or more the diameter of the hearth, and the iron ore formed above the tuyere A large empty tank 25 for sedimentation and collection of dust is formed inside the shaft above the layer of stone and coke.

That is, by setting the inner diameter of the shaft to be at least twice the diameter of the hearth and providing a large empty tank 25 at the upper part of the shaft, the inside of the shaft is reduced as the empty tank gas velocity which rises as the empty tank 25 is reduced. To sediment and collect the dust, and effectively suppress the discharge of the dust to the outside of the system. Further, at the lower part of the furnace, there are provided three or more stages of tuyeres 7 for feeding air vertically, and The tuyere of one of the tuyeres is a bottom tuyere located at the bottom of the furnace, thereby generating a raceway at the bottom of the furnace, raising the temperature of the bottom and increasing the temperature of the bottom of the furnace. Stable combustion can be obtained so as to make the temperature distribution uniform at high temperature throughout.

Reference numeral 24 denotes a layer of raw iron ore and coke in the furnace, the lowermost position of which is formed above the tuyere 7, and an upper space, which is the surface of the raw material layer, has an empty tank 25 formed in the shaft. This becomes a settling tank for fine dust.

When hot air is sent from dozens of tuyeres 7 (for example, three upper stages, six middle stages, and six lower stages (bottom of the furnace) in this case) opened in the furnace wall, the raceway in the furnace will 8 so that the heat is completely distributed. The high-temperature hot air blown from here passes through the stepped raw material ore and the coke to reduce and melt the iron ore and drop pig iron down to be taken out.

鉱 The accumulated slag is also taken out of the system. Since there is a large empty tank 25 in the upper part of the furnace and there are only a few steps of iron ore and coke, the velocity of the combustion gas is about 1/3 to 1/10 or less than that of the conventional combustion gas. No dust is blown out of the furnace. That is, they float and circulate without reaching the furnace top, and settle in the lower raw material layer.

FIG. 2 is a schematic enlarged view of the temperature distribution of the tuyere when three tuyeres are provided in the vertical direction. In this case, control valves (see FIG. (Not shown), so that the upper and lower portions of the furnace bottom can be controlled so that a large amount of air is sent to places where the heat is low in the height direction.

According to this, the temperature at the furnace bottom is made more uniform as compared with the case of the one-stage tuyere as shown in FIG. 6A and the case of the two-stage tuyere as shown in FIG. However, the temperature distribution at the bottom of the furnace is not sufficiently uniform.

In the present invention, the lower one of the tuyeres is a bottom tuyere located at the bottom of the furnace as shown in FIG. 3, thereby generating a raceway also at the bottom of the furnace. The temperature of the bottom can be raised to a higher temperature. As a result, the temperature distribution at the bottom of the furnace can be made uniform at a higher temperature as compared with the case where three-stage tuyeres are provided only in the vertical direction shown in FIG. It was. In this case, a special furnace bottom brick structure and a bottom tuyere made of brick can generate a high-temperature raceway also at the bottom of the furnace and stabilize the high-temperature temperature distribution at the furnace bottom more uniformly. .

FIGS. 4A and 4B are partial cross-sectional views of a bottom tuyere portion. For example, FIG. 4A shows a protruding nozzle brick tuyere structure system, in which a protruding nozzle made of refractory brick from the furnace bottom. 31 is a new technology structure that prevents molten iron having a high specific gravity from flowing into the bottom tuyere. FIG. 4 (B) shows a porous brick tuyere structure system in which a bottom tuyere portion of a hearth brick is constructed of a special porous brick material 32, air passes through the porous brick, and an upper part thereof is formed. And a high-temperature raceway is formed.

In the present invention, it is possible to use a fine powder constituting most of the dust, a fine iron ore called a pellet feed, or a sintered ore-processed or pellet-processed one. In addition, a raceway is formed in the furnace by providing (1) blast temperature control, (2) oxygen enrichment control, and (3) blast humidity (g / Nm ³ ) control in each of the upper, lower, and lower tuyeres. It is also possible. Also, these raceways are designed to occur in combustion with coke.

の Since the present invention is configured as described above, it has the following effects.

The temperature difference in the raceway generated by the one-stage tuyere and the two-stage tuyere having the same level as the conventional one or the raceway generated by the upper, middle and lower three-stage tuyere increases in the furnace bottom height direction. Therefore, the molten pig iron or slag decreases while descending to the bottom of the furnace, and solidifies at the bottom of the furnace and cannot be discharged smoothly from the tap hole or the slag port, resulting in a so-called fecal clogging phenomenon. In this case, it becomes a serious problem in the production operation of the furnace.

In the present invention, the three-stage tuyere has three stages of high-temperature raceways, and the one-stage tuyere is a bottom tuyere. As a result, the molten iron or the molten slag does not solidify before reaching the furnace bottom as before, and the production operation of the furnace is greatly stabilized.

In particular, in the case of the three-stage tuyere level, the air blown from the upper and middle tuyeres and the lower tuyeres (bottom tuyeres) depending on the temperature condition of the furnace bottom and the temperature of the molten pig iron and molten slag, respectively ( 1) raising and lowering the temperature, (2) raising and lowering the oxygen enrichment, and (3) raising and lowering the temperature to control the hot uniform hot iron temperature and the molten slag temperature. It becomes possible.

In addition, since it has a configuration in which fine powder and the like are difficult to discharge, there is an advantage that, in addition to fine iron ore, steel dust such as converter dust, electric furnace dust, and oil-containing rolling scale powder can be used. In the case of a raw material having many fine powders, it is possible to omit the work of sinter or pellet processing.

転 Steel dust such as converter dust, electric furnace dust and oil-impregnated rolling scale powder generated as industrial waste in the iron mining industry can also be treated in the blast furnace. The ability to treat various types of dust has a great advantage in resource recycling.

In addition, low-grade shredder waste and shredder dust industrial waste of electric products such as automobiles and refrigerators can be used as recycled resources by using the melting furnace of the present invention. That is, due to the low gas flow velocity in the space above the shaft (empty tank), dust particles of the shredder can be prevented from scattering outside the furnace, and the high temperature (1000 ° C.) at the furnace top gasifies metals such as zinc. This high temperature promoted the decomposition of dioxins and PCBs and made it a non-polluting gas.

It is a model partial sectional view of a vertical shaft blast furnace of a reference example. It is a temperature distribution model enlarged view of the furnace bottom at the time of providing an upper middle lower lower tuyere. FIG. 4 is a partial cross-sectional view of a three-stage tuyere (of which one stage is a bottom tuyere) according to the present invention. (A) and (B) are cross-sectional views of main parts of another bottom tuyere portion according to the present invention. It is a model partial sectional view of the conventional general vertical shaft blast furnace. (A) is a temperature distribution diagram of the furnace bottom in the case of the conventional one-stage tuyere, and (B) is a temperature distribution diagram of the furnace bottom in the case of the conventional two-stage tuyere.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Furnace bed 2 Hot metal bed 3 Slag bed 4 Furnace belly 5 Shaft 7 Tuyere 8 Raceway 9 Raw material 15 Raw material charging surface 24 Layer of raw iron ore and coke in furnace 25 Empty tank

Claims (3)

In a melting furnace such as a vertical shaft cupola or a blast furnace provided with a shaft on the furnace belly surrounding the upper part of the hearth having a hot metal bed and a slag bed,
At the lower part of the furnace, three or more tuyeres for feeding air in the vertical direction are provided, and one of the tuyeres is a bottom tuyere located at the bottom of the furnace. A large empty tank for sedimentation and collection of dust is formed inside the shaft above the layer of iron ore and coke formed above the tuyere with a diameter of at least twice the floor. Furnace. 2. The melting furnace according to claim 1, wherein the bottom tuyere has a projection nozzle brick tuyere structure. 2. The melting furnace according to claim 1, wherein the bottom tuyere has a porous brick tuyere structure.

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