JP6922864B2 - Pig iron manufacturing equipment and pig iron manufacturing method using it - Google Patents

Description

The present invention relates to a pig iron production facility using an oxygen blast furnace and a hot air blast furnace, and a pig iron production method using the same.

In recent years, steelworks are strongly required to save energy against the background of global environmental problems and fossil fuel depletion problems. In response to this, recent blast furnace operations have been strongly promoted with low reducing agent ratio (low RAR) operations.

Typical blast furnace, oxygen coke and pulverized coal and hot air (air is heated to about 1200 ° C.) is reacted in a tuyere, thereby generating a CO and H ₂ gas (reducing gas), these reducing gases It is reducing iron ore in the furnace. Previously, small blast furnaces with an internal volume of ^{about 100 m 3} were operated, but with the demand for productivity and the development of technology, the capacity of blast furnaces has increased year by year, and in recent years, ^{large blast furnaces of 5000 m 3} class have become mainstream. ing. However, as the size of the blast furnace increases, it becomes necessary to increase the strength of coke and sinter charged into the blast furnace, and as a result, agglomeration of raw materials has developed. On the other hand, in recent years, the quality of raw materials has been deteriorating, and it has become difficult to obtain high-strength raw materials as in the past. For this reason, technological development for a small blast furnace that can operate even with low-strength raw materials is required. In addition, due to the stricter safety requirements in recent years, it is required to reduce the size of not only the blast furnace but also its peripheral equipment as much as possible to improve maintainability.

As one of the blast furnace miniaturization technologies, there is research on oxygen blast furnaces. In a normal blast furnace, hot air (air heated to a high temperature of about 1200 ° C.) is blown from the tuyere, whereas in an oxygen blast furnace, pure oxygen is blown from the tuyere. Since this oxygen blast furnace can reduce the volume of reducing gas flowing inside the blast furnace by half as compared with a normal blast furnace, there is an advantage that the size of the blast furnace can be significantly reduced while maintaining the production amount. In addition, since a hot air furnace is not required, peripheral equipment can be significantly reduced in size.

However, in an oxygen blast furnace, since pure oxygen is blown from the tuyere, there is a problem that combustion by pure oxygen occurs at the tuyere and the flame temperature becomes extremely high. As described above, if the flame temperature is too high, troubles such as damage to the tuyere and the furnace wall and malfunction of loading in the blast furnace due to volatilization of the slag component occur. Therefore, in an oxygen blast furnace, it is essential to adopt a technique of blowing a tuyere coolant together with pure oxygen from the tuyere to control the flame temperature to an appropriate temperature (2000-2600 ° C.).

By the way, in Patent Document 1, in an oxygen blast furnace, CO ₂ or H ₂ O (steam) is blown from the tuyere as a tuyere coolant, and the flame temperature of the tuyere tip is lowered by using these endothermic pyrolysis reactions, which is appropriate. A technique for controlling the temperature to a high temperature is disclosed.

Further, Patent Document 2 discloses a method of blowing blast furnace top gas as a tuyere coolant together with pure oxygen and pulverized coal from the tuyere of an oxygen blast furnace. It is known that in this known method, CO ₂ contained in the furnace top gas causes endothermic thermal decomposition at the tuyere tip, so that the flame temperature can be lowered and controlled to an appropriate temperature.

Japanese Unexamined Patent Publication No. 60-159104 Japanese Unexamined Patent Publication No. 62-27509

By the way, the technique disclosed in Patent Document 1 is a _{method of blowing steam or CO 2} gas together with oxygen from the tuyere of an oxygen blast furnace. However, since the tuyere of a blast furnace is generally made of copper and has a water-cooled specification, the tuyere The surface is cooled to about several tens of degrees Celsius. Therefore, when water vapor is blown from the tuyere, a part of the water vapor is cooled at the tuyere, drained, and flows out as water, and the entire amount of water vapor cannot be used for the endothermic reaction. Therefore, in this case, it is difficult to control the flame temperature to the target value by steam blowing. In _{the case of CO 2} gas, the problem of drainage does not occur, but on the other hand, pure CO ₂ gas does not exist in nature. For example, from the top gas of an oxygen blast furnace containing about 50 vol% of _{CO 2 gas, the PSA method (} It is necessary to separate only _{CO 2 gas using a CO 2} separation facility based on the pressure fluctuation separation method). _{However, when CO 2} gas is blown from the tuyere of an oxygen blast furnace, a large amount of CO ₂ gas of ^{30,000 Nm 3 / h is required per blast furnace.} Therefore, in the case of an oxygen blast furnace, if a _{gas separation facility is used to generate a large amount of CO 2} gas that is only required to be blown from the tuyere, a huge gas separation facility is required, and the facility becomes large on the contrary. Occurs.

Further, since the method of Patent Document 2 is a method of recirculating and blowing the top gas of the oxygen blast furnace itself into the tuyere, a large ancillary equipment such as a gas separation equipment becomes unnecessary. However, since about half of the top gas of the oxygen blast furnace is CO and the other half is CO ₂ , only half of the blown gas contributes to the endothermic pyrolysis reaction. Therefore, in order to lower the flame temperature at the tip of the tuyere to an appropriate temperature, it is necessary to blow a large amount of furnace top gas of ^{10,000 m 3 / h per tuyere.} However, considering that the purpose of an oxygen blast furnace is to make it smaller than a normal blast furnace, it is desirable to reduce the gas flow rate blown from the tuyere as much as possible due to the equipment layout, and a large amount of gas is required. Blast furnace top gas circulation that blows tuyere cooling gas is not preferable.

An object of the present invention is a pig iron production facility using an oxygen blast furnace, which can reduce the flow rate of cooling gas to the oxygen blast furnace, can efficiently cool the tuyere temperature of the oxygen blast furnace without the need for ancillary equipment, and the pig iron production facility thereof. The purpose is to propose a method for producing pig iron using the above.

As a result of diligent research to solve the above-mentioned problems of the prior art and to realize the above-mentioned object, the inventors develop a new pig iron manufacturing facility described below and a pig iron manufacturing method using the same. It came to.

That is, the pig iron production facility of the present invention is a pig iron production facility that uses an oxygen blast furnace and a hot air blast furnace, in which pure oxygen, a reducing material, and a cooling gas for the tuyere are blown from the tuyere, and substantially from the top of the furnace. Air is generated by the heat generated when an oxygen blast furnace that generates nitrogen-free oxygen blast furnace gas and the oxygen blast furnace gas and an oxygen-containing gas that does not substantially contain nitrogen are burned to generate hot air furnace combustion exhaust gas. It is a pig iron production facility including a hot air furnace that heats up and supplies it to the hot air blast furnace, and is configured so that a part of the combustion exhaust gas of the hot air furnace becomes a cooling gas for a tuyere of the oxygen blast furnace. ..

In the pig iron manufacturing equipment according to the present invention configured as described above,
(1) Using pure oxygen gas as the oxygen-containing gas that does not substantially contain nitrogen.
(2) As the oxygen-containing gas containing substantially no nitrogen, a gas obtained by mixing the hot air furnace combustion exhaust gas with pure oxygen is used.
(3) As the oxygen-containing gas containing substantially no nitrogen, a gas obtained by mixing water vapor with pure oxygen is used.
Is considered to be a more preferable solution.

Further, in the pig iron production method of the present invention, in the pig iron production method using the pig iron production equipment, a part of the hot air furnace combustion exhaust gas generated in the hot air furnace and substantially free of nitrogen is used for the tuyere of the oxygen blast furnace. It is a pig iron production method characterized by being used as a cooling gas.

According to the iron iron production facility and the iron iron production method according to the present invention, oxygen blast furnace gas that is substantially free of nitrogen discharged from an oxygen blast furnace that uses pure oxygen is used, and nitrogen is also used in a hot air furnace without using air. Since it is possible to generate hot air by burning oxygen blast furnace gas using an oxygen-containing gas that does not contain oxygen, it is possible to generate hot air furnace combustion exhaust gas _{that is substantially free of nitrogen and is composed of almost only CO 2.} Will be.

Then, since a part of the combustion exhaust gas from the hot air furnace is blown from the tuyere of the oxygen blast furnace as cooling gas for the tuyere, a large amount of CO ₂ gas is _{blown without using a large-scale CO 2 separation facility such as PSA.} Since it can be blown into the mouth and the combustion exhaust gas from the hot air furnace is almost _{only CO 2} , the feathers can be blown with a small amount of tuyere cooling gas compared to the case where the blast furnace top gas is recirculated and blown into the tuyere. You will be able to properly control the mouth temperature. As a result, it is possible to reduce the size of the oxygen blast furnace and peripheral equipment because it is sufficient to provide a blowing equipment that can blow a small amount of tuyere cooling gas without adding extra equipment such as _{CO 2 separation.} Become.

Further, in a preferred example of the present invention, in a hot blast furnace facility, a part of the hot blast furnace combustion exhaust gas is recirculated without using air and mixed with pure oxygen to obtain an oxygen-containing gas substantially free of nitrogen. After that, it was made to burn with oxygen blast furnace gas. Further, in another preferred example of the present invention, steam is mixed with pure oxygen to obtain an oxygen-containing gas that is substantially free of nitrogen, and then burned with oxygen blast furnace gas.

As a result, the tuyere tip temperature can be controlled to an appropriate value simply by blowing a small amount of hot air furnace combustion exhaust gas into the tuyere. Furthermore, in the hot air furnace, a part of the hot air furnace combustion exhaust gas or steam is mixed and diluted without using pure oxygen alone, but this causes an abnormality that occurs in pure oxygen combustion while maintaining the nitrogen-less condition. It is possible to suppress the generation of high-temperature combustion flames, and it is possible to suppress damage to the fire-resistant material in the hot-air furnace while maintaining the effect of cooling the tuyere of the hot-air furnace combustion exhaust gas. Furthermore, according to the present invention, the portion of the combustion exhaust gas from the hot air furnace that has not been recirculated is discharged to the outside of the system, but the hot air furnace _{is substantially free of nitrogen and is composed of almost only CO 2.} Since combustion exhaust gas is generated, it can be applied to CCS (Carbon digest Capture and Storage, CO ₂ capture and storage) and CCU (Carbon capture and storage, CO ₂ utilization), and can also contribute to _{CO 2 emission reduction.} Is.

It is a figure which shows the structure of an example of the pig iron manufacturing facility of this invention. It is a figure which shows the structure of another example of the pig iron manufacturing facility of this invention. It is the schematic which shows the tuyere used for the oxygen blast furnace of the pig iron production facility of this invention together with the burner for a blast furnace tuyere. It is a figure which shows the structure of the other example of the pig iron manufacturing facility of this invention. It is a figure which shows the structure of the pig iron manufacturing facility of the comparative example 1. FIG. It is a figure which shows the structure of the pig iron manufacturing facility of the comparative example 2. It is a figure which shows the structure of the pig iron manufacturing facility of the comparative example 3. It is a figure which shows the structure of the pig iron manufacturing facility of the comparative example 4.

FIG. 1 is a diagram showing a configuration of an example of a pig iron manufacturing facility of the present invention. In the configuration shown in this figure, 1 is an oxygen blast furnace, 1'is a hot air blast furnace, and 2 is an oxygen blast furnace gas (OB gas) and an oxygen-containing gas (oxygen in this case) generated from the top of the oxygen blast furnace 1. A hot air furnace that generates hot air for blowing into the attached hot air blast furnace 1', 3 is a burner for blowing preheated gas generated by partially burning the oxygen blast furnace gas into the furnace, and 4 is oxygen, etc. in the oxygen blast furnace 1. The tuyere used to blow in 4'is the tuyere of a hot air blast furnace. In the operation of the oxygen blast furnace 1 having the above-described configuration, ore, coke and the like are charged from the top of the furnace, and pulverized coal and the like are blown together with oxygen from the tuyere 4 at the bottom of the oxygen blast furnace. Hot air blast furnace gas (B gas) is generated from the hot air blast furnace. Although not shown in the figure, the B gas of the hot air blast furnace is used as fuel for power generation in the steelworks in the same manner as a normal steelworks.

FIG. 2 is a diagram showing the configuration of another example of the pig iron manufacturing facility of the present invention. In the configuration shown in FIG. 2, the same members as those in the example shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. In the configuration shown in this figure, in addition to the configuration shown in FIG. 1, a hot air furnace combustion exhaust gas recirculation path 5 that mixes a part of the hot air furnace combustion exhaust gas generated from the hot air furnace 2 with pure oxygen supplied to the hot air furnace 2. Is provided. This makes it possible to dilute pure oxygen (for example, about 20 vol% of oxygen).

The feature of the present invention is that in the pig iron production facility shown in FIGS. 1 and 2, a part of the hot air furnace combustion exhaust gas generated from the hot air furnace 2 and substantially free of nitrogen is blown from the tuyere 4 of the oxygen blast furnace 1. The point is that it is used as a cooling gas. Hereinafter, the pig iron production facility of the present invention will be specifically described.

In a general blast furnace, a blow pipe and a blowing lance such as pulverized coal are attached to the tuyere, but in the oxygen blast furnace 1, pure oxygen is blown from the tuyere 4 instead of hot air, so that the pulverized coal has poor ignitability. I have a problem. Therefore, in the oxygen blast furnace 1, a burner for the oxygen blast furnace tuyere is attached to the tuyere 4 in order to promote ignition of the pulverized coal.

FIG. 3 is a schematic view showing a tuyere used in an oxygen blast furnace of a pig iron production facility together with a burner for an oxygen blast furnace tuyere. In the configuration shown in this figure, reference numeral 11 denotes an oxygen blast furnace tuyere burner attached to the tuyere 4. The oxygen blast furnace tuyere burner 11 is installed by pressing it against the tuyere 4 so as not to leak gas to the outside. Here, the burner 11 for the tuyere of the oxygen blast furnace is composed of a coaxial multiplex tube including a central tube 12-1, an inner ring tube 12-2, and an outer ring tube 12-3. As an example, cooling gas is blown from the central ring 12-1, pulverized coal is blown from the ring road between the inner ring road 12-2 and the central pipe 12-1, and the outer ring road 12-3 and the inner ring road 12-3 are blown. Pure oxygen is blown from the annular conduit between the annular tube 12-2 and the annular tube. Then, a raceway 6 in which pure oxygen and pulverized coal react with each other is formed in the oxygen blast furnace at the tip of the tuyere 4.

The oxygen blast furnace tuyere burner 11 having the above-described configuration strongly mixes these gases and pulverized coal in the tuyere 4, and enables rapid ignition and rapid combustion immediately after exiting the tuyere 4. Further, in the oxygen blast furnace, since the amount of gas in the furnace is small, there is a problem that the temperature rise of the charged material in the upper part of the furnace becomes insufficient. In order to avoid this, in the oxygen blast furnace 1, the oxygen blast furnace gas (OB gas) is partially burned by the burner 3 so as to be about 1000 ° C., and then the preheated gas is blown into the blast furnace shaft portion. There is.

In the oxygen blast furnace 1, oxygen is not blown from the tuyere 4 but oxygen is blown, so that almost no nitrogen is generated in the furnace. Therefore, the oxygen blast furnace gas (OB gas) discharged from the oxygen blast furnace 1 is nitrogen-free. That is, the composition of the top gas of a normal hot air blast furnace is about 50% nitrogen, _{25% CO + H 2 and} 25% CO ₂ + H ₂ O, whereas the oxygen blast furnace 1 has 50% _{CO + H 2 and CO.} The composition is about 50% of ₂ + H _{2 O.} Therefore, as in the hot metal production facility shown in FIG. 1, if the oxygen blast furnace gas of the oxygen blast furnace 1 is burned with pure oxygen and used for the operation of the hot air furnace 2 for the attached hot air blast furnace 1', The blast furnace combustion exhaust gas is also oxygen-free. Further, since the steam can be naturally separated by cooling the hot air furnace combustion exhaust gas to room temperature, the hot air furnace combustion exhaust gas discharged from the hot air furnace 2 as a result is _{only CO 2} or the hot air furnace is operated with excess oxygen. In some cases, the hot blast furnace combustion exhaust gas contains only _{CO 2 and oxygen and does not contain nitrogen.}

In the hot air furnace, the temperature must be set to about 1100 ° C. to 1500 ° C. due to the heat resistance restriction of the refractory. On the other hand, when pure oxygen and oxygen blast furnace gas generated from an oxygen blast furnace are burned, combustion gas having an extremely high temperature exceeding 3000 ° C. may be generated, and it may not be possible to pour it into a hot air furnace as it is. Therefore, it is preferable to use a method of lowering the flame temperature by mixing and diluting pure oxygen with another gas. However, it is not preferable that nitrogen is contained in the diluting gas as shown below. Therefore, in the preferred example of the present invention shown in FIG. 2, the hot air furnace combustion exhaust gas of the hot air furnace 2 itself is recirculated and used as a nitrogen-free dilution gas.

Here, since the hot air furnace combustion exhaust gas generated from the hot air furnace 2 using the oxygen blast furnace gas and the oxygen-less oxygen-containing gas also does not contain nitrogen, even if this method is used, almost no nitrogen is contained, which is substantially the same. It is possible to generate hot air furnace combustion exhaust gas composed only of CO _2. When mixing the hot air furnace combustion exhaust gas with the pure oxygen here, as shown in FIG. 2, the pure oxygen and the hot air furnace combustion exhaust gas may be mixed in front of the combustor of the hot air furnace 2, or the hot air furnace. Since the combustion exhaust gas itself does not contribute to the combustion reaction, the oxygen blast furnace gas and pure oxygen may be burned in the combustor and then mixed with the hot air furnace combustion exhaust gas. Moreover, you may use both together.

Further, as the tuyere coolant to be blown into the tuyere 4 of the oxygen blast furnace 1, a substance that causes a thermal decomposition reaction at the tuyere tip at a high temperature is preferable. The tip of the tuyere is filled with coke. For example, CO ₂ and H ₂ O react with coke to cause the following endothermic pyrolysis reaction, so that they also have a large cooling effect.
C (coke) + CO ₂ = 2CO-172.42kJ / mol
_{C (coke) + H 2 O} = CO + H 2 -131.27kJ / mol
However, CO, since H _2, N ₂ gas does not cause thermal decomposition reaction, there is only a small effect of cooling the corresponding sensible be blown into the tuyere. Therefore, the tuyere coolant blown into the tuyere is preferably a substance that causes thermal decomposition as much as possible, that is, a substance having a high concentration of _{CO 2} and H _{2 O.} The hot air furnace combustion exhaust gas shown above contains almost no nitrogen and is _{composed of almost only CO 2} , so it is suitable as a tuyere cooling gas.

In the present invention, there are oxygen blast furnace gas substantially free of nitrogen, oxygen-containing gas substantially free of nitrogen, and hot air furnace combustion exhaust gas substantially free of nitrogen, but these are when blown into the tuyere tip. In addition, the amount of nitrogen may be reduced to such an extent that it does not interfere with the heat absorption and thermal decomposition reaction at the tip of the tuyere, and it is not always necessary that the amount of nitrogen is zero. For example, if the nitrogen concentration is controlled so that the nitrogen concentration is 10 vol% or less, preferably 3 vol% or less, a sufficient endothermic pyrolysis reaction occurs at the tip of the tuyere due to the hot air furnace combustion exhaust gas blown from the tuyere. The invention holds.

Examples 1 and 2 and Comparative Examples 1 and 4 were prepared as shown below, and Examples 1 and 2 and Comparative Examples 1 and 4 were compared. 2 and 4 show the configurations of the pig iron manufacturing facilities of Examples 1 and 2, and FIGS. 5 to 8 show the configurations of the pig iron manufacturing facilities of Comparative Examples 1 to 4. However, in the examples shown in FIGS. 4 to 8, FIG. 1 The same members as those shown in the above are designated by the same reference numerals, and the description thereof will be omitted.

<Example 1>
As a first example conforming to the present invention, in the oxygen blast furnace 1 in which oxygen is blown from the tuyere 4, as shown in FIG. 2, the oxygen blast furnace gas containing almost no nitrogen in the oxygen blast furnace 1 is poured into the hot air furnace 2. Based on the example. Further, in the hot air furnace 2, an oxygen-containing gas in which oxygen and the combustion exhaust gas of the hot air furnace are mixed is generated, and is mixed with the oxygen blast furnace gas in the hot air furnace 2 and burned. The hot blast furnace combustion exhaust gas of the hot blast furnace 2 was almost _{only CO 2} , and the hot blast furnace combustion exhaust gas was sent to the tuyere 4 of the oxygen blast furnace 1, and oxygen gas was blown from the tuyere 4 together with pulverized coal.

<Example 2>
As a second example conforming to the present invention, an oxygen blast furnace gas containing almost no nitrogen in the oxygen blast furnace 1 is poured into the hot blast furnace 2, and the hot blast furnace 2 generates an oxygen-containing gas in which oxygen and steam are mixed. Inside the hot air furnace 2, it is mixed with the oxygen blast furnace gas and burned. Since the water vapor blown into the hot air furnace 2 is naturally liquefied and separated when the exhaust gas is cooled, the hot air furnace combustion exhaust gas is almost _{only CO 2} , and the hot air furnace combustion exhaust gas is sent to the tuyere 4 of the oxygen blast furnace 1 and at the same time. Oxygen gas was blown from the tuyere 4 together with pulverized coal.

<Comparative example 1>
Patent are those disclosed in Document 1, as shown in FIG. 5 performs CO ₂ separation by CO ₂ separation equipment 21 from an oxygen blast furnace gas (OB gas) using a PSA, wings separated CO ₂ as the cooling gas The oxygen blast furnace 1 was operated by blowing through the mouth 4.
<Comparative example 2>
Similarly, in the example shown in Patent Document 1, as shown in FIG. 6, steam was blown from the tuyere 4 as a cooling gas to operate the oxygen blast furnace 1.
<Comparative example 3>
This is an example shown in Patent Document 2, and as shown in FIG. 7, the oxygen blast furnace gas was circulated from the tuyere 4 and blown as cooling gas to operate the oxygen blast furnace 1.
<Comparative example 4>
As shown in FIG. 8, as the oxygen-containing gas of the hot air furnace, air is used instead of pure oxygen, and the oxygen blast furnace gas (OB gas) and air generated from the top of the oxygen blast furnace 1 are used in the hot air furnace 2. The oxygen blast furnace 1 was operated by burning it in a boiler and blowing the hot air furnace combustion exhaust gas generated in the hot air furnace 2 as cooling gas from the tuyere 4.

First, in comparing Examples 1 and 2 and Comparative Examples 1 to 4 conforming to the present invention described above, the specifications of the oxygen blast furnace were unified. That is, the amount of tapped iron was 10,000 t / day, the number of tuyere was 40, the coke ratio was 375 kg / t, and the pulverized coal ratio was 200 kg / t. In addition, as a preheating gas injection, the blast furnace gas was partially burned with pure oxygen so as to reach 1000 ° C., and the blast furnace gas was blown at ^{135,000 Nm 3 / h from the blast furnace shaft portion.} Further, various tuyere coolants (cooling gas) are blown in an amount such that the tuyere tip temperature becomes 2400 ° C.

The results of comparing Examples 1 and 2 and Comparative Examples 1 to 4 are shown in Table 1 below.

As can be seen from the results shown in Table 1, in Examples 1 and 2, the tuyere temperature ^{was adjusted by blowing 781 Nm 3} / h of hot air furnace combustion exhaust gas (nitrogen-less) as the temperature control gas (cooling gas) into each tuyere. It was confirmed that the temperature can be controlled to 2400 ° C and that it can be carried out without any special ancillary equipment.

On the other hand, in _{Comparative Example 1 using CO 2 separation, the flow rate of CO 2} gas as the temperature control gas was the same as that in Example, and the tuyere temperature could be controlled with a relatively small amount of temperature control gas. However, in Comparative Example 1, since a large amount of CO ₂ must be generated from the oxygen blast furnace gas, a large-scale PSA-based CO ₂ separation facility is required, and it can be confirmed that this is not preferable in terms of excessive incidental facilities. rice field.

Further, in Comparative Example 2 in which water vapor is blown from the tuyere, the flow rate of water vapor as the temperature control gas is 906 Nm ³ / h, which is slightly higher than that of the example, but there is an advantage that a relatively small flow rate of water vapor is sufficient. It could be confirmed. However, in Comparative Example 2, it was found that there was a problem from the viewpoint of controllability of the tuyere tip temperature because water vapor had a problem of draining on the tuyere surface.

Further, in Comparative Example 3 in which the oxygen blast furnace gas was recirculated and blown from the tuyere, it was confirmed that the embodiment could be implemented without any special ancillary equipment. However, in Comparative Example 3, about half of the oxygen blast furnace gas is CO and the other half is CO ₂ , so the concentration of _{CO 2} that causes endothermic pyrolysis is low. As a result, the amount of oxygen blast furnace gas blown was as high as 1260 Nm ³ / h, so that the blowing equipment around the tuyere became huge and it was found that it was difficult to implement due to the layout around the tuyere.

Furthermore, in Comparative Example 4 when air was used instead of pure oxygen as the oxygen-containing gas of the hot air furnace, more than half of the exhaust gas from the hot cloth furnace became nitrogen, so the concentration of _{CO 2 causing endothermic thermal decomposition.} Has decreased. As a result, it was found that, as in Comparative Example 3, there was a problem that the flow rate of the hot air furnace combustion exhaust gas blown into the tuyere became huge.

From the above results, it was confirmed that the methods of Examples 1 and 2 of the present invention have no drawbacks and can perform significant operations as compared with the methods of Comparative Examples 1 to 4.

According to the pig iron production facility of the present invention, _{blast furnace combustion exhaust gas, which is substantially free of nitrogen and is composed of almost only CO 2} , is generated, so that pure oxygen, a reducing material, and cooling gas are blown from the tuyere. An oxygen blast furnace that generates an oxygen blast furnace gas that is substantially free of nitrogen from the top of the furnace, an oxygen blast furnace gas that is generated from the top of the oxygen blast furnace, and an oxygen-containing gas that is substantially free of nitrogen are used side by side. It is operated using not only the pig iron production equipment consisting of a hot air furnace that generates hot air to the hot air blast furnace, but also the pig iron production equipment that consists of a hot air furnace that generates hot air to the attached hot air blast furnace. It can be applied not only to pig iron manufacturing equipment consisting of a furnace, but also to CCS (Carbon dioxide Capture and Storage, CO ₂ recovery and storage) and CCU (Carbon capture and utilization, CO ₂ utilization), and contributes to _{CO 2 emission reduction.} It is possible to do.

1 Oxygen blast furnace 1'hot air blast furnace 2 hot air furnace 3 burner 4 tuyere 4'hot air blast furnace tuyere 5 hot air furnace combustion exhaust gas recirculation path 6 raceway 11 blast furnace tuyere burner 12-1 center tube 12-2 inner ring tube 12-3 Outer ring pipe 21 CO ₂ separation equipment

Claims (5)

This is a hot iron blast furnace that uses an oxygen blast furnace and a hot air blast furnace. Pure oxygen, a reducing material, and a cooling gas for the tuyere are blown from the tuyere, and oxygen blast furnace gas with a nitrogen concentration of 10 vol% or less is generated from the top of the tuyere. An oxygen blast furnace and a hot air furnace that heats air by heat generated when the oxygen blast furnace gas and an oxygen-containing gas having a nitrogen concentration of 10 vol% or less are burned to generate hot air furnace combustion exhaust gas and supplies the hot air blast furnace to the hot air blast furnace. A hot iron production facility comprising a part of the combustion exhaust gas from a hot blast furnace so as to be a cooling gas for a tuyere of the oxygen blast furnace. The pig iron production facility according to claim 1, wherein pure oxygen gas is used as the oxygen-containing gas having a nitrogen concentration of 10 vol% or less. The iron iron production facility according to claim 1, wherein a gas obtained by mixing pure oxygen with the hot air furnace combustion exhaust gas is used as the oxygen-containing gas having a nitrogen concentration of 10 vol% or less. The pig iron production facility according to claim 1, wherein a gas obtained by mixing water vapor with pure oxygen is used as the oxygen-containing gas having a nitrogen concentration of 10 vol% or less. In the pig iron manufacturing method using the pig iron manufacturing equipment according to any one of claims 1 to 4.
A method for producing pig iron, which comprises using a part of the combustion exhaust gas of a hot blast furnace having a nitrogen concentration of 10 vol% or less generated in the hot blast furnace as a cooling gas for a tuyere of the oxygen blast furnace.

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