JPH0730374B2 - Method for generating high temperature hot air in a metallurgical furnace - Google Patents

Description

The present invention relates to a method for generating high-temperature hot air in a metallurgical furnace, and more specifically to a high-temperature hot air in a metallurgical furnace that uses both a conventional hot-air stove and a continuous heating furnace. It depends on the generation method.

2. Description of the Related Art Conventionally, a hot blast stove used in a metallurgical furnace such as a blast furnace is a hot blast stove that alternately repeats heat storage and heat radiation as shown in FIG. 4, and the combustion chamber and the heat storage chamber are divided into two types. There are an external combustion type, which is used, and an internal combustion type, in which both are integrated. In the case of the external combustion type, it is generally composed of 4 hot stoves,
Some are made up of three units. FIG. 5 is an explanatory diagram of the external combustion type. First, the conventional hot blast stove will be described with reference to FIGS. 4 and 5. In FIG. 4, the hot blast stoves of A and B are burning and C and D are radiating heat (blowing). Blower 16
The air whose pressure has been increased by the cold air tube 1 is stored in the C and D heat storage chambers 2c.
And 2d, the heat is exchanged with the glitter bricks 3 in the heat storage chamber, the temperature reaches a predetermined temperature, the hot air tube 4 is passed through, and the heat is supplied to a metallurgical furnace 18 such as a blast furnace. The hot blast stoves of A and B are in the process of burning (accumulating heat), and the combustion gas is supplied to the combustion chambers 6a and 6b by the gas pipe 5. Exhaust gas that has undergone heat exchange with the glitter bricks in the heat storage chamber 2 is discharged from the chimney 8 into the atmosphere through the exhaust gas flue 7. At this time, the cold air valve 9a of the hot blast stoves A and B during combustion,
9b and hot air valves 10a and 10b are closed. The temperature 11 at the top of the getter brick depends on the blast temperature, but it is 1200 to 1500 ℃, and the temperature 12 at the bottom of the getter brick is 200 to 300 ℃, and the temperature difference between the top and bottom is very large. Therefore, the upper half of the gitter brick uses silica stone bricks that are resistant to high temperatures, and the lower half uses alumina bricks. Is managed by.

The problems that such hot blast stoves currently have are: (1) Degradation and collapse of bricks due to the transformation point of silica stone-gitter bricks (abnormal thermal expansion due to transformation occurs in the temperature range of 150 ° C to 300 ° C). In order to avoid the danger of, the lower end temperature of silica gitter brick is controlled to operate at 400 ℃ or more, but this limits the hot-air stove operation range (low-temperature blasting silica lower end control temperature).

(2) The conventional hot-blast stove system consists of three to four units, but the brick cost accounts for about 30% of the construction cost, which is a bottleneck for reducing construction cost.

(3) Silica brick is used in the upper part of the heat storage chamber and alumina brick is used in the lower part, but the price of alumina brick is higher than that of silica brick.

There is a problem such as.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention aims to solve these problems, and specifically, by using a continuous heating furnace together, eliminates the disadvantages of low-temperature air blowing and ensures the flexibility of air blowing temperature. And again
It is an object of the present invention to provide a high-temperature hot air generation method capable of reducing brick costs.

<Structure of Invention> Means for Solving Problems and Actions Thereof The present invention relates to two or more heat storage type hot air stoves that alternately repeat heat storage and heat dissipation, and an air heating furnace that can continuously perform heat exchange. In the high temperature hot air generating method in combination with, in the heating furnace, the air for metallurgical furnace blowing is preheated to a temperature equal to or higher than the transformation point of the silica brick by exchanging heat with the exhaust gas of the regenerative hot air furnace in a combustion state, and this preheating air is used. Is supplied to the heat storage type hot-air stove in the heat storage state,
It is characterized in that it is heated to a predetermined temperature by exchanging heat with a high-temperature gitter brick and then blown into a metallurgical furnace.

The structure and operation of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing a hot air generating method according to the present invention, FIG. 2 is an explanatory view of an example of a continuous heating furnace used in the present invention, and FIG. 3 shows a hot air generating method in an embodiment. It is an explanatory view shown, Drawing 4 is an explanatory view showing the conventional hot-air generation method, and Drawing 5 is an explanatory view of the conventional outside heating type hot-blast stove.

The method for generating high temperature hot air according to the present invention will be described with reference to FIGS. 1 and 2.

Reference numeral 14 is a conventional external heat type hot air stove which uses at least two units (Fig. 1 shows an example of using two units). Reference numeral 15 is a continuous heating furnace, an example of which is shown in FIG. Further, 18 is a metallurgical furnace, 8 is a chimney, and 16 is a blower.

The air blown by the blower 16 is a hot air stove in a burning state.
14a exhaust and enter the continuous heating furnace 15 which is kept at a predetermined temperature by a burner 24 if necessary, preheated by heat exchange in a large number of heat transfer tubes 23, assembled in a header 25, and passed through a valve 9b. It enters the hot-air stove 14b in the heat storage state, is further heated to a higher temperature by heat exchange with the gitter brick 3b heated to a high temperature, and is 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 exhausted from the chimney 8.

At this time, the preheating temperature of the air is adjusted by the combustion of the burner 24, if necessary, and is supplied to the hot-blast stove 14b at a transformation temperature (150 to 300 ° C.) of the silica gitter brick 3 or higher, for example, 400 ° C. Therefore, all the gitter bricks of the hot-blast stove heat storage chamber used in the present invention can use silica stone bricks,
Since it is not necessary to use expensive alumina bricks as in a conventional furnace, it is extremely cost effective.

The method of adjusting the temperature of the air blown to the metallurgical furnace 18 is as follows: (1) The exit side preheating temperature is controlled by adjusting the burner combustion gas amount of the continuous heating furnace.

(2) Mix the preheated air 17 at the hot air outlet side.

(3) Mixing grooved air at temperature levels supplied by 3 to 4 hot stoves.

And the like.

Examples Hereinafter, examples will be further described.

FIG. 3 shows an embodiment of the present invention in which two hot blast stoves and one continuous heating stove are combined.

The hot blast stoves 14a and 14b were used for one combustion and one blast, and the continuous heating furnace 15 was continuously used. That is, in FIG. 3, the hot blast stove 14a is in the process of burning (while storing heat) and the hot blast stove 14b is in the process of blowing air (dissipating heat).
The heat was exchanged with the air supplied to the blower 15, blown by the blower 16, and 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 hot-air stove 14b, and heat-exchanges with the silica stone-gitter brick stored at high temperature to become hot air, which is mixed with the preheated air 17 and heated to 1200 ° C. As a metallurgical furnace.

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

As mentioned above, the preheated air supplied to the hot stove is 500 ° C.
Since it is supplied by the above, it was possible to operate for a long time without any trouble without considering the transformation point of the silica gitter brick.

<Effects of the Invention> As described above, the present invention combines two or more heat storage type hot-air stoves that alternately repeat heat storage and heat dissipation with an air heating furnace that can continuously perform heat exchange. In the hot air generation method, the air for metallurgical furnace blowing is heat-exchanged with the exhaust gas of the regenerative hot air stove in the combustion state to preheat it to a temperature above the transformation point of the silica brick, and the preheated air is stored in the heat storage state. Type hot blast stove, which is heated to a predetermined temperature by exchanging heat with a high-temperature gitter brick, and then blown into a metallurgical furnace. is there. That is, 1) The total construction cost is lower than that of the conventional hot stove method. In the case of the method of the present invention, the total number of hot-air stoves can be reduced, the brick weight can be reduced accordingly, and the cost-effective silica bricks can be fully adopted. Cost reduction.

2) Since it is not necessary to consider the transformation point of the silica stone brick, which has been a problem in the conventional method, it is possible to operate with flexibility from high temperature air blowing to low temperature air blowing.

3) Brick drying equipment is indispensable when starting the hot-air stove from a cold state, but in the case of the present invention, since a continuous heating oven is an alternative, brick drying equipment is unnecessary and cost reduction is achieved. Contribute.

4) When it is necessary to increase the capacity of the hot blast stove by upgrading the capacity of the blast furnace at the time of refurbishment, the existing hot blast stove can be utilized and the objective can be achieved by adding and combining continuous heating furnaces. Construction costs are cheaper.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a hot air generating method according to the present invention, and FIG.
FIG. 4 is an explanatory view of an example of a continuous heating furnace used in the present invention, FIG. 3 is an explanatory view showing a hot air generating method in an embodiment, and FIG.
FIG. 5 is an explanatory view showing a conventional hot air generating method, and FIG. 5 is an explanatory view of a conventional external heating hot air stove. Reference numeral 1 ... Cold air pipe, 2 ... Heat storage chamber 3 ... Gitter brick, 4 ... Hot air pipe 5 ... Fuel gas, 6 ... Combustion chamber 7 ... Exhaust gas valve, 8 ... Chimney 9 ... Cold air valve, 10 …… Hot air valve 11 …… Gitter brick top temperature 12 …… Gitter brick bottom temperature 13 …… Quartz stone Gitter brick bottom temperature 14 …… Hot air oven, 15 …… Continuous heating furnace 16 …… Blower, 17 …… Preheated air 18 …… Metallurgical furnace 19 …… Fuel gas amount control valve 21 …… Combustion air, 23 …… Heat transfer tube 24 …… Burner, 25 …… Header

Claims (1)

[Claims] 1. A method for producing high-temperature hot air, which comprises a combination of two or more heat-storage type hot air stoves that alternately repeat heat storage and heat dissipation and an air heating furnace capable of continuously performing heat exchange, wherein air for blowing in a metallurgical furnace is provided. In the heating furnace, preheat to a temperature above the transformation point of the silica brick by exchanging heat with the exhaust gas of the heat storage type hot stove in the combustion state, and supplying this preheated air to the heat storage type hot stove in the heat storing state, the high temperature getter A method for generating high-temperature hot air, which comprises heat-exchanging with bricks, heating to a predetermined temperature, and then blowing the air into a metallurgical furnace.