JPS63140009A - Method for generating high-temperature hot air for metallurgical furnace - Google Patents

Abstract

PURPOSE:To assure flexibility of a blast temp. and to reduce brick costs by combining hot stoves which alternately repeat heat regeneration and radiation and continuous heating furnace. CONSTITUTION:The continuous heating furnace 15 is used in combination with at least two units of the external heat type hot stoves 14. The air held at a prescribed temp. by a fan 16 enters the continuous heating furnace 15 maintained at the prescribed temp. by the exhaust gas from the hot stove 14a in the combustion state and a burner 24 at need. Said air is preheated by a heat exchange and is collected by a heater from which the air enters the hot stove 14b in the heat regeneration state. The air is further heated up by the heat exchange with gitter bricks 3b heated to a high temp. and is fed to a metallurgical furnace 18. On the other hand, the exhaust gas from the heating furnace 15 is discharged from a chimney 8. The preheating temp. of the air at this time is controlled by the combustion of the burner 24 at need and the air is supplied at the transformation temp. of the bricks 3 and is supplied to the hot stove 14b. Silica bricks are, therefore, usable for all the checker bricks in the regeneration chamber of the hot stoves.

Description

[Detailed Description of the Invention] <Object of the Invention> Industrial Application Field The present invention relates to a method for generating high-temperature hot air in a metallurgical furnace, and more particularly, the present invention relates to a method for generating high-temperature hot air in a metallurgical furnace that uses both a conventional hot-air furnace and a continuous heating furnace. It concerns the method of occurrence.

BACKGROUND OF THE INVENTION Conventionally, hot blast furnaces used in metallurgical furnaces such as blast furnaces are hot blast furnaces that alternately store and release heat, as shown in Figure 4, and are separated into a combustion chamber and a heat storage chamber. There are two types: the external combustion type, which is a combination of both, and the internal combustion type, which is a combination of both. In the case of an external combustion type, it generally consists of four hot air stoves, but
Some are composed of three units. FIG. 5 is an explanatory diagram of an external combustion type. First, a conventional hot-blast stove will be explained using FIGS. 4 and 5. In FIG. 4, hot-blast stoves A and B are combusting, and C and D are dissipating heat (blowing air). Air blower fj
The air pressurized at 116 enters the heat storage 'J2c and 2d of C and D from the cold air pipe 1, exchanges heat with the Gitter bricks 3 in the heat storage chamber, reaches a predetermined temperature, passes through the hot air pipe 4, and is sent to metallurgical equipment such as blast furnaces. is supplied to the furnace 18. The hot air stoves A and B are in the process of combustion (heat storage), and fuel gas is supplied to the combustion chambers 6a and 6b through the gas pipe 5. The exhaust gas that has undergone heat exchange with the bricks in the heat storage chamber 2 passes through the exhaust gas flue 7 and is released into the atmosphere from the chimney 8. At this time, the cold air valves 9a and 9b and the hot air valves 10a and 10b of the hot air stoves A and 8 are closed. The temperature 11 at the upper end of the Gitter brick is 1200 to 1500°C, depending on the blowing temperature, and the temperature 12 at the lower end of the Gitter brick is 200 to 300°C, and the temperature difference between the upper and lower ends is very large. For this reason, the upper half of the Gitzter cooking tiles is made of silica brick, which is resistant to high temperatures, and the lower half is made of alumina brick, but in order to avoid the transformation temperature of silica brick,
The lower end temperature 13 of the silica brick is controlled at 400°C or higher.

The current problems faced by hot air stoves such as the
In the temperature range of , abnormal thermal expansion occurs due to transformation.

) In order to avoid the risk of brick deterioration and collapse due to low-temperature blasting, the lower end temperature of the silica gitter bricks is controlled at 400°C or higher. lower end control temperature).

(2) The conventional hot air stove system consists of three or four units, but the brick cost accounts for a large proportion of the construction cost (approximately 30%), which is a bottleneck in reducing construction costs.

(3) The upper part of the heat storage chamber uses silica bricks, and the lower part uses alumina bricks, but alumina bricks are more expensive than silica bricks.

There are other problems.

Problems to be Solved by the Invention The present invention aims to solve these problems. Specifically, by using a continuous heating furnace in combination, the disadvantages of low temperature air blowing can be eliminated, and The purpose of the present invention is to provide a method of generating high-temperature hot air that can reduce the cost of bricks.

<Structure of the Invention> Means for Solving the Problems and Their Effects The present invention provides two or more regenerative hot blast furnaces that alternately repeat heat storage and heat release, and an air heating furnace that can continuously perform heat exchange. In the method for generating high-temperature hot air in combination with is supplied to a regenerative hot blast stove in a heat storage state,
It is characterized in that it is heated to a predetermined temperature by exchanging heat with high-temperature Gitter bricks, and then air is blown into a metallurgical furnace.

Hereinafter, the structure and operation of the means of the present invention will be explained with reference to the drawings.

FIG. 1 is an explanatory diagram showing the hot air generation method according to the present invention, FIG. 2 is an explanatory diagram of an example of a continuous heating furnace used in the present invention, and FIG. 3 is an explanatory diagram showing the hot air generation method in the embodiment. FIG. 4 is an explanatory diagram showing a conventional hot air generation method, and FIG. 5 is an explanatory diagram of a conventional external heating type hot air stove.

The high temperature hot air generation method of the present invention will be explained with reference to FIGS. 1 and 2.

Reference numeral 14 denotes a conventional external heating type hot air stove, and at least two units are used (FIG. 1 shows an example in which two units are used).

15 is a continuous heating furnace, an example of which is shown in FIG. In addition, 18 is a metallurgical furnace, 8 is a chimney, and 16 is a sending pipe.
It is a machine.

The air blown by the blower $111G enters the continuous heating furnace 15 which is maintained at a predetermined temperature by the exhaust of the hot air stove 14a in a combustion state and by the burner 24 as necessary,
It is preheated by heat exchange in a large number of heat transfer tubes 23, collected in a header 25, passes through a valve 9b, enters a hot blast furnace 14b in a heat storage state, and is further heated to a high temperature by heat exchange with a Gitter brick 3b heated to a high temperature. and sent to the metallurgical furnace 18 through the hot air valve 10b. On the other hand, the exhaust gas from the heating furnace 15 is discharged from the chimney 8.

At this time, the preheating temperature of the air is adjusted fl15 by combustion in the burner 24 as necessary, and the air is supplied to the hot blast furnace 141) at a temperature higher than the transformation temperature (150 to 300°C) of the silica ginter brick 3, for example, 400°C. . Therefore, silica bricks can be used for all the Gitter bricks in the hot blast furnace heat storage chamber used in the present invention, and there is no need to use expensive alumina bricks as in conventional furnaces, which is extremely advantageous in terms of cost.

In addition, the method for adjusting the temperature of the air sent to the metallurgical furnace 18 is (1)
The outlet preheating temperature is controlled by adjusting the amount of burner combustion gas in the continuous heating furnace.

(2) Mix preheated air 17 on the outlet side of the hot air stove.

(3) Mixing the air in the grooves at the temperature level supplied by three to four hot air stoves.

This is done by methods such as

Example This will be further explained below with reference to Examples.

FIG. 3 shows an embodiment of the present invention using a combination of two hot blast stoves and one continuous heating furnace.

One hot air stove IAa and 14b is used for combustion and one for blowing,
The continuous heating furnace 15 was used continuously. That is, in FIG. 3, the hot air stove 14a is in the process of combustion (“heat storage”)
b indicates that air is being blown (during heat dissipation), and the exhaust gas from the hot stove 14a is supplied to the continuous heating furnace 15 at 600°C, exchanges heat with the air blown by the blower 1G, and is discharged from the chimney 8 at 150°C. . On the other hand, the air preheated to 500°C in the continuous heating furnace 15 is supplied to the heat 11#514b, exchanges heat with the silica gitter bricks stored at high temperature, becomes hot air, mixes with the preheated air 17, and reaches 1200°C. It was supplied to the metallurgical furnace as hot air.

Although the temperature of the hot air coming out of the hot air furnace decreases over time, the temperature of the hot air supplied to the metallurgical furnace could be kept constant by changing the mixing ratio with the preheated air 17.

In addition, as shown below, the preheated air supplied to the hot air stove is 50%
Since it was supplied at 0°C, it was possible to operate for a long time without any problems without considering the transformation point of the silica Gitter brick.

<Effects of the Invention> As explained above, the present invention combines two or more regenerative hot blast furnaces that alternately repeat heat storage and heat radiation, and an aerodynamic zero-heat furnace that can continuously perform heat exchange. In the method for generating high-temperature hot air, the metallurgical furnace air is preheated in the heating furnace to a temperature higher than the transformation point of the silica brick by exchanging heat with the exhaust gas of the regenerative hot blast furnace in a combustion state, and this preheated air is used for heat storage. This is a method of generating high-temperature hot air, which is characterized by an opening that supplies the air to a regenerative hot air furnace, exchanges heat with high-temperature Gitter bricks, heats it to a predetermined temperature, and then blows the air into the metallurgical furnace. It has the following advantages. In other words: 1) The total construction cost is lower than the conventional hot stove method. In the case of the method of the present invention, the number of hot blast stoves can be reduced, the weight of bricks can be reduced accordingly, and silica bricks, which are low in cost efficiency, can be fully adopted, even taking into account the cost increase associated with the addition of continuous heating furnaces. This results in a total cost reduction.

2) Since there is no need to consider the transformation point of silica bricks, which was a problem in the conventional method, flexible operation from high-temperature to low-temperature ventilation is possible.

3) Brick drying equipment is always required when starting up a hot air stove from a cold state, but in the case of the present invention, a continuous heating furnace is used as an alternative, so brick drying equipment is not required, resulting in cost reduction. Contribute.

4) When renovating a blast furnace, if it is necessary to increase the capacity of the hot blast furnace due to increased capacity, etc., the purpose can be achieved by utilizing the existing hot blast furnace and adding a continuous heating furnace and combining them. Construction costs will be lower.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the hot air generation method according to the present invention, Figure 2 is an explanatory diagram showing the hot air generation method according to the present invention;
The figure is an explanatory diagram of an example of a continuous heating furnace used in the present invention, FIG. 3 is an explanatory diagram showing a hot air generation method in an embodiment, and FIG.
The figure is an explanatory diagram showing a conventional heat III generation method, and FIG. 5 is an explanatory diagram of a conventional external heat type hot air stove. Code 1... Cold air pipe 2... Heat storage chamber 3... Gitter brick 4... Hot air pipe 5... Fuel gas 6... ...Burning to 7
...Exhaust gas valve 8...Chimney"...
...Cold air valve 10...Hot air valve 11.
... Gitter brick upper end temperature 12 ... Gitter brick lower end temperature 13 ... Silica stone gitter brick lower end temperature 14 ... Hot stove 15 ...
・Continuous heating furnace 1G... Delivery machine 17.
...Preheating air 18 ...Metallurgical furnace

Claims (1)

[Claims] Two or more heat storage type hot air stoves that alternately repeat heat storage and heat radiation,
In a method for generating high-temperature hot air in combination with an air heating furnace capable of continuous heat exchange, air for blowing the metallurgical furnace is heat-exchanged with exhaust gas from a regenerative hot air furnace in a combustion state in the heating furnace to form silica bricks. The preheated air is preheated to a temperature above the transformation point of A method for generating high-temperature hot air.