KR930004473B1 - Process for making iron in the blast furnace - Google Patents

Abstract

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Description

Method for manufacturing iron in the furnace

1 is a vertical sectional view of the furnace according to the invention.

2 is a horizontal end view of the furnace of the present invention taken along line II-II of FIG.

3 is a graph showing the relationship between the fuel cost of the blast furnace and the relative position of the tuyeres according to the present invention.

4 is a graph showing the relationship between the silicon content in the molten iron and the relative position of the tuyere.

5 is a schematic cross-sectional view of a burner according to the invention.

* Explanation of symbols for main parts of the drawings

11: furnace body 12: air vent

13: air vent 14: laminated line

28: burner body 29: pilot burner

The present invention relates to a method for producing iron in a steelmaking furnace, and more particularly to a blowing of gas for preheating the charges introduced into the furnace.

In conventional blast furnace operations for making iron ore into pig iron, the blowing of hot air has relied mainly on blowing through the tuyere, with almost no exception. Nitrogen, which occupies 79% of the blowing gas content, does not contribute to the reduction but contributes enormous heat to the charge accumulated between the height of the furnace and the lamination line, thereby accelerating gas reduction. In other words, nitrogen serves as a heat source and aids the coke to act as a reducing agent.

This is therefore very effective in preheating the charge present on top of the no shaft, eliminating the need for heat supply to preheat the charge.

Recently, various methods have been proposed for the operation of furnaces in which blowing gas through the tuyere consists mainly of oxygen, in order to improve the productivity of the furnace operation or to enable the use of the furnace government gas in the material of synthetic chemicals. . For example, one method is described in Japanese Patent Application Publication No. 159104/85 as follows.

(1) Through the Roh's government, the charge, mainly iron ore and coke, is charged into the furnace.

(2) Blow through the furnace vents with pure oxygen, pulverized coal and temperature-controlled gases to prevent flame temperatures from rising at the vents.

(3) Through the middle height of the furnace, nitrogen-free preheating gas is blown to preheat the charge.

(4) With the pure oxygen blown, the coke contained in the charge is burned to melt and reduce the charged iron ore and to generate nitrogen free gas from the government of the furnace.

However, this method is very difficult to sustain stable furnace operation with low fuel costs over a long period of time.

It is an object of the present invention to provide a method for producing iron in a smelting furnace which can sustain stable operation with low fuel costs over a long period of time.

For this purpose, a method for producing iron in the furnace according to the present invention, providing a furnace having a tuyere 12 in the lower portion of the furnace body, and a furnace having a tuyere for the preheating gas (13). And arranging the tuyeres 13 in a range of 0.15 to 0.60 downward from the stacked line 14 of the furnace main body, where the distance between the stacked line and the height 15 of the tuyere 12 is 1.0. In the method for producing iron in the furnace consisting of the step of injecting preheating gas into the furnace through the tuyere 13, the furnace is a mixture of coal and flame temperature control agent pulverized with a mixture of more than 40% by volume of oxygen It is characterized in that the supply through (12).

The objects, further objects and advantages of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings.

An embodiment of the furnace according to the present invention will be described with reference to FIG.

1 is a vertical sectional view illustrating the furnace of the present invention. The load consisting of iron ore, coke and solvent is charged into the furnace to load up to a certain level of stacking line 14. The blast furnace 12 is provided in the furnace main body 11. More than 40% by volume of oxygen gas, pulverized coal and flame temperature regulators are introduced into the furnace through the tuyere 12. The tuyeres 13 for introducing the preheating gas are provided at a height separated by 0.50 from the lamination line when the distance from the lamination line to the tuyere is 1.0. The tuyeres consist of a set of 16 entrances at the same height, which are inclined 25 ° downward from the horizontal. Preheating gas is introduced into the furnace to preheat the charges through these tuyeres 13. Thus, the blowing gas having more than 40% by volume of oxygen causes the coke and pulverized coal to be completely burned, and the iron ore is melted and reduced to pig iron and slag because the generated reducing gas has a high temperature. 2 is a horizontal end view taken along the line II-II of FIG. Sixteen air vents 13 are provided on the circumference at equal intervals.

[Location of blowhole]

In the embodiment, the position of the tuyere is provided at a height of 0.05 below the lamination line when the distance between the height of the tuyere entrance and the lamination line is 1.0. However, the position may be set at any point in the range of 0.15 to 0.60 below the lamination line. A more preferred range of positions is 0.30 to 0.55 from the lamination line.

We will describe the reasons for limiting the range of these locations.

3 is a graph showing the relationship of the relative position of the tuyeres 13 with respect to the fuel cost during the operation of the furnace. When the distance between the height of the air inlet opening and the lamination line is 1.0 in the abscissa, the ratio of the distance from the lamination line to the position of the tuyeres is indicated. FIG. 4 graphically shows the relationship between the silicon in the molten pig iron and the relative positions of the tuyeres 13 for introducing the preheating gas. Similarly to Fig. 3, in the abscissa, when the distance between the height of the tuyere and the stacking line is 1.0, the ratio of the distance between the position of the tuyere and the stacking line is represented.

As can be seen in FIG. 3, if the distance between the height of the air inlet and the stacking line is 1, in the range of 0.15 to 0.60 below the stacking line, the fuel cost is sufficiently low, in the range of 500 to 600 kg per ton of molten pig iron, Also, there is almost no defect. If the tuyeres are installed below 0.15 below the lamination line, a reduction in the melting temperature or damage to the cladding may occur if the furnace is operated at a fuel rate of less than 650 kg per tonne of molten pig iron. If the tuyeres are located at 0.60 or more above the lamination line, a decrease in the molten iron temperature or a congestion of the molten iron may occur. It is not possible to maintain stable furnace operation for long periods of time unless the tuyeres are installed below 0.15 or above 0.60 from the lamination line, unless the furnace is operated at a fuel cost of more than 700 kg per tonne of molten pig iron.

As can be seen in FIG. 4, the silicon content in the molten iron is reduced to almost 0.30 wt% or less when the position of the tuyeres is set at 0.15 to 0.60 below the lamination line. This is a significant advantage for the operation of the furnace since it eliminates the need for desilicon work after tapping of the molten iron.

The position of the tuyeres for the preheating gas is more preferably in the range of 0.33 to 0.55 below the lamination line. This range further reduces the fuel cost and the silicon content in the molten iron.

By limiting the position range of the tuyeres of the preheating gas as described above, it is possible to reduce the fuel cost, to prevent the operation disaster, and to produce the low silicon molten iron.

[The height of the tuyeres and the number at each height]

The preheating gas is blown in accordance with the result of measuring the charge temperature or the gas temperature by the probe provided in the middle part of the furnace side. Blowing of the preheating gas is via a single height or multiple height vents. In the case of blowing through multi-height tuyeres, the tuyeres of each height installed on the circumference of the furnace wall are divided into groups of several zones, and at the same time between the upper group and the lower group, which are located vertically in the same volume of gas volume and gas temperature If changed, the effect of preheating is much faster than with air conditioning through a single height vent. In the case of multiple height tuyeres, in the case of a tuyer, it is preferable that the equipment of the tuyeres is designed such that the amount of gas or the gas temperature varies between each tuyer or between adjacent tuyeres at the same height. This is because a variety of selective adjustments can be made in these installations. In addition, in the case of the blowing through the multi-height tuyere, each tuyere is preferably positioned so as to be parallel to each other with respect to the vertical height in terms of allowing the uniformly flowing up along the periphery of the furnace wall.

When the same amount of gas is blown without temperature change, it is preferable to blow the hot preheating gas through the branch pipe derived from the ring-shaped pipe. It is not necessary to particularly limit the number of the blowholes at each of these heights. 8 to 18 tuyeres are preferred in order to make the gas composition and the temperature governing around the furnace wall near the stack line height almost uniform. Also, the number of tuyeres having different heights is preferably 1 to 4.

[Angle of tuyeres]

The downward inclination angle of the tuyeres to be installed in the furnace main body is preferably larger than the stabilization angle of the charge. This is because the powder particles of the charge block the opening of the tuyeres. The downward slope of the tuyeres to the furnace with respect to the horizontal height is preferably in the range of 20 ° to 50 °. If the downward slope is less than 20 °, the powder particles of the charge block the opening of the tuyeres. On the other hand, considering that the stability angle of the charge is up to 45 ° to 50 °, the downward slope need not be more than 50 °. In addition, a downward inclination of more than 50 ° is undesirable in terms of assisting the main body because the blow hole must be widened due to its acute angle.

[Preparation of Preheating Gas]

Two methods can be considered to prepare the preheating gas. One method is to produce combustion furnaces installed around the furnace by furnace gas and oxygen from the furnace. In the practice of the present invention, in order to uniformly blow the preheating gas into the furnace, the hot blast induction pipe is brought up to the height of the no shaft and then connected to the fire resistant heavy ring-shaped pipe, which is also connected to each tuyer by many branch pipes. Let's go. Another method is a gas burner having a fuel gas supply pipe 21, an oxygen supply pipe 22 and a gas temperature control gas supply pipe 25 is installed in the tuyeres to introduce preheating gas into the furnace. Each burner independently adjusts the amount and temperature of the preheating gas by controlling the amount of fuel gas and the amount of oxygen gas. Such conveying pipes leading to the burners need not be fireproof. Unlike the first method, the hot air is blown out from the large-scale combustion, the burners are installed at each tuyeres, and the gas temperature and quantity can be freely and simply controlled at each tuyeres. In addition, there is no need to install a heavy ring hot air blowing pipe on the no shaft. In operation there is a rapid response to changes in furnace conditions.

5 schematically illustrates a cross section of a burner to be used in the present invention. The pilot burner 29 is provided at the position where oxygen is injected. The outer side of the burner body is covered with a shell made of steel sheet. The gas supply pipe 25 is also coupled to the burner body to freely adjust the temperature of the gas generated in the burner. The cooling water pipe is composed of a water supply pipe 23 and a drain pipe 24.

Claims (6)

(Correction) providing a furnace having a tuyere 12 in the lower part of the furnace body, providing a furnace with a tuyeres 13 for preheating gas, and between the stacked line and the height 15 of the tuyere 12. Arranging the tuyeres 13 in a range of 0.15 to 0.60 downward from the stacking line 14 of the furnace main body at a distance of 1.0, and injecting preheating gas into the furnace through the tuyeres 13. In the method for producing iron in the furnace, the furnace is produced in the furnace, characterized in that the coal and flame temperature control agent pulverized with a mixture of more than 40% by volume of oxygen is supplied through the tuyere (12). How to. (Correction) The method according to claim 1, wherein the tuyeres are set in a range of 0.30 to 0.55 of the distance. (Correction) The method according to claim 1 or 2, characterized by setting the tuyeres to a single range of the furnace body. (Correction) The method according to claim 1 or 2, characterized by setting the tuyeres to at least two different ranges of the furnace body. (Correction) The method for producing iron in a furnace according to claim 1 or 2, characterized in that the tuyeres are set at an inclination angle of 20 to 50 ° with respect to the horizontal height. (Correction) The furnace according to claim 1 or 2, characterized in that it is arranged with respect to the tuyeres to include a gas burner having a fuel gas supply pipe, an oxygen supply pipe, and a gas induction pipe to control the gas temperature. Method for manufacturing iron in

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