JP6977739B2 - Method of blowing granular solid reducing agent - Google Patents

Description

The present invention relates to a blast furnace tuyere for blowing a granular solid reducing agent into a blast furnace, a blast furnace tuyere facility, and a method for blowing a granular solid reducing agent using these.

In recent years, energy saving has been strongly demanded in steelworks due to global environmental problems and fossil fuel depletion problems. In response to this, in recent blast furnace operations, low reducing agent ratio (low RAR) operations are being strongly promoted. In a typical blast furnace, blowing the pulverized coal and 1200 ° C. about hot air from tuyere and oxygen react coke and pulverized coal and hot air, to produce a reducing gas such as CO and H ₂ gas, these reducing Iron ore in the blast furnace is reduced by gas. Previously, the mainstream operation was to use only coke or heavy oil blown from coke and tuyere as a reducing agent, but nowadays, fine pulverized coal that is finely pulverized to 100 μm or less is blown from the tuyere. Has been established, and some of the reducing agents have been replaced from coke to pulverized coal. Furthermore, in recent years, as will be described later, a technique for blowing reducing materials such as waste plastic into a blast furnace has been established. With the development of these tuyere blowing technologies, the amount of energy used in the ironmaking process has been significantly reduced.

In the blast furnace, the reducing agent such as pulverized coal blown from the tuyere causes a combustion reaction with the oxygen-containing gas blown together. The oxygen remaining without reacting with the reducing agent, carbon dioxide (CO ₂ ) and water vapor (H ₂ O) generated by the combustion reaction with the reducing material react with the coke in the coke packed bed in front of the tuyere. Finally, it becomes a high-temperature reducing gas (hereinafter referred to as bosh gas) composed of carbon monoxide (CO), hydrogen (H ₂ ), and nitrogen (N _2). The larger the amount of the blown reducing agent burned at the tuyere tip, the smaller the amount of coke consumed. Therefore, improving the burning rate of the blown reducing agent at the tuyere tip is extremely important for energy saving in the ironmaking process.

The Bosch gas generated at the tip of the tuyere is a gas that has the function of reducing iron ore, and at the same time, it pushes out the coke in front of the tuyere and plays a role of forming a combustion space called a raceway in front of the tuyere. The raceway is a space that is indispensable for sufficiently burning the reducing material such as pulverized coal blown from the tuyere, and if the raceway cannot be formed, the combustion rate of the reducing material blown from the tuyere will drop significantly. do. Therefore, in order to achieve energy saving in the blast furnace and the ironmaking process, it is important to form a raceway in front of the tuyere and to stably supply the reducing agent to the raceway.

With the progress of blast furnace technology, technology for blowing various raw materials other than pulverized coal from the tuyere has been developed. The general tuyere blowing material is the above-mentioned pulverized coal, but another typical tuyere blowing material is plastic blowing technology. In Patent Document 1, a chlorine-containing polymer resin material is separated and removed from a film-like resin and then melt-solidified to be processed into a granular synthetic resin, and for non-film-like resins, the chlorine-containing polymer resin is separated and removed and crushed. A method of treating, granulating, and air-transporting the granules to the blast furnace is disclosed.

Japanese Unexamined Patent Publication No. 9-170009

In the technique disclosed in Patent Document 1, waste plastic is processed into granules of about 6 mm and blown into a blast furnace from a 25 mm blowing lance. However, according to the results of long-term waste plastic blowing operation in an actual blast furnace, waste plastic with a large particle size has a high wear force with respect to pulverized coal. Causes wear on the tuyere and lance. Furthermore, when a large amount of waste plastic is transported by airflow, clogging occurs in the lance and piping at a certain frequency. If the amount of waste plastic blown in is increased with the current tuyere and lance equipment specifications, troubles due to wear and clogging of the tuyere and lance will increase, making it practically difficult to operate the blast furnace.

The present invention has been made in view of the above-mentioned problems, and is a blast furnace tuyere that can suppress an increase in tuyere wear and tuyere clogging, a blast furnace tuyere facility, and a granular solid reducing agent blowing using these. The purpose is to provide a crowding method.

The features of the present invention for solving such a problem are as follows.
[1] A blast furnace tuyere for blowing a granular solid reducing agent into a blast furnace, the main flow hole for blowing a gas containing oxygen into the blast furnace, and the granular solid reducing material installed above the main flow hole. The sub-flow hole is provided at a position where the granular solid reducing agent can be blown into the raceway formed by the gas containing oxygen blown from the main flow hole. Blast furnace tuyere.
[2] The blast furnace tuyere according to [1], wherein the distance L between the centers of the discharge port of the main flow hole and the discharge port of the sub flow hole satisfies the following equation (1).
L ≦ 0.48 × {(ρf × V ² ) / (ρp × d)} ^1/4 -1 / 2D ... (1)
In the above equation (1), L is the distance (m) between the centers of the discharge port of the main flow hole and the discharge port of the sub flow hole, ρf is the Bosch gas density (kg / m ³ ), and V. Is the bosh gas flow rate per tuyere (m ³ / s), ρp is the apparent density of coke (kg / m ³ ), d is the particle size of coke (m), and D is the main flow hole. Is the inner diameter (m) of.
[3] A blast furnace tuyere facility for blowing a granular solid reducing agent into a blast furnace, which is installed above the mainstream tuyere and a mainstream tuyere having a main flow hole for blowing a gas containing oxygen into the blast furnace. The side flow tuyere has a side flow tuyere having a secondary flow hole for blowing the granular solid reducing material, and the side flow tuyere is formed in a raceway formed by a gas containing oxygen blown from the main flow hole. , A blast furnace tuyere facility provided at a position where the granular solid reducing agent can be blown from the sub-flow hole.
[4] The blast furnace tuyere equipment according to [3], wherein the distance L between the centers of the discharge port of the main flow hole and the discharge port of the sub flow hole satisfies the following equation (1).
L ≦ 0.48 × {(ρf × V ² ) / (ρp × d)} ^1/4 -1 / 2D ... (1)
In the above equation (1), L is the distance (m) between the centers of the discharge port of the main flow hole and the discharge port of the sub flow hole, ρf is the Bosch gas density (kg / m ³ ), and V. Is the bosh gas flow rate per tuyere (m ³ / s), ρp is the apparent density of coke (kg / m ³ ), d is the particle size of coke (m), and D is the main flow hole. Is the inner diameter (m) of.
[5] The method for blowing a granular solid reducing agent using the tuyere for a blast furnace according to [1] or [2], in which a gas containing oxygen is blown into the blast furnace from the main flow hole to form a raceway. , A method of blowing a granular solid reducing agent into the raceway from an auxiliary flow hole.
[6] A method for blowing a granular solid reducing agent using the tuyere equipment for a blast furnace according to [3] or [4], in which a gas containing oxygen is blown into the blast furnace from the main flow hole to form a raceway. A method of blowing a granular solid reducing agent into the raceway from a secondary flow hole.
[7] The method for blowing a granular solid reducing agent according to [5] or [6], wherein the gas containing oxygen is a gas containing 60% by volume or more of oxygen.
[8] The method for blowing a granular solid reducing agent according to any one of [5] to [7], wherein the granular solid reducing material is a waste plastic.

In the blast furnace tuyere and the blast furnace tuyere facility according to the present invention, a gas containing oxygen is blown into the blast furnace from the main distribution hole to form a raceway, and a granular solid is formed in the raceway from a secondary distribution hole different from the main distribution hole. Blow in the reducing agent. In this way, by blowing the granular solid reducing agent into the raceway from the sub-flow hole different from the main flow hole for blowing the oxygen-containing gas forming the raceway, the blowing speed of the granular solid reducing agent can be slowed down. It is possible to suppress the increase in tuyere wear due to the granular solid reducing agent. Further, since the granular solid reducing agent is blown from the secondary flow hole, the occurrence of tuyere clogging does not increase even if the diameter of the main flow hole is reduced in order to strengthen the formation of the raceway.

It is sectional drawing of the blast furnace tuyere 10 which concerns on this embodiment. It is a graph which shows the relationship between the Froude number (Fr), the height (H) of a raceway 30, and the ratio (H / D) of the inner diameter (D) of a main flow hole 12. FIG. 3 is a schematic cross-sectional view of the tuyere equipment 20 for a blast furnace according to another embodiment. FIG. 4 is a schematic cross-sectional view of the blast furnace 40 corresponding to Example 1, Comparative Example 1 and Comparative Example 2. It is sectional drawing of the blast furnace 50 corresponding to Example 2, Comparative Example 3 and Comparative Example 4.

Hereinafter, the present invention will be described in detail through embodiments of the present invention. The embodiment shown below is an embodiment in which a blast furnace tuyere having a main flow hole and a sub flow hole is provided in the blast furnace.

As described above, when the granular solid reducing agent is blown from the blast furnace tuyere, it is important to form a raceway in front of the tuyere to sufficiently burn the granular reducing agent and gasify it. At this time, if the granular solid reducing agent blown from the tuyere for the blast furnace is not rapidly gasified, it will be deposited in the coke packed bed and the air permeability will be deteriorated. That is, in order to ensure the air permeability of the blast furnace, the granular solid reducing agent blown from the tuyere for the blast furnace is promptly supplied to the raceway, heated by high temperature gas and high temperature radiation, ignited and burned to gasify. Is important.

FIG. 1 is a schematic cross-sectional view of the blast furnace tuyere 10 according to the present embodiment. The tuyere 10 for a blast furnace is provided above the main flow hole 12 for blowing oxygen-containing gas (in a normal blast furnace, oxygen-enriched hot air) and a secondary for blowing a granular solid reducing agent. It has a distribution hole 14. The main flow hole 12 is a flow hole into which an oxygen-containing gas is blown, and a bosh gas is generated by a combustion / gasification reaction between the blown oxygen-containing gas and coke to form a raceway 30. The sub-flow hole 14 is a flow hole different from the main flow hole 12, and is a flow hole into which the granular solid reducing agent is blown. Along with the granular solid reducing agent, the conveyed gas flows through the sub-flow hole 14 at a flow rate of, for example, about 2 to 20 m / s. Since the gas flow rate of the sub-flow hole is small, the raceway 30 is not formed by injecting gas from the sub-flow hole. Therefore, in order to promptly supply the granular solid reducing material blown from the secondary distribution hole to the raceway 30, the secondary distribution hole 12 is formed at a position where the granular solid reducing material can be directly blown into the raceway 30. The distribution hole 14 may be installed.

Therefore, in the blast furnace tuyere 10 according to the present embodiment, the sub-flow hole 14 is provided so that the discharge port of the sub-flow hole 14 is below the upper end of the raceway 30. As a result, the granular solid reducing agent can be quickly supplied to the raceway 30 from the sub-flow hole 14. On the other hand, the shape of the raceway 30 changes depending on the shape of the tuyere and the blast furnace operating conditions.

It is known that the shape of the raceway 30 has a strong correlation with the Froude number Fr. The Froude number Fr is a dimensionless number represented by the following equation (2).

Fr = (ρf / ρp) ^1/2 × U / (g × d) ^1/2 ... (2)
Here, ρf is the Bosch gas density (kg / m ³ ), and U is the Bosch gas flow velocity (m / s) at the discharge port of the main flow hole 12 assuming that Bosh gas is blown from the main flow hole 12. Ρp is the apparent density of coke in front of the tuyere (kg / m ³ ), d is the particle size of coke in front of the tuyere (m), and g is the gravitational acceleration (= 9.81 m / s ^2). ).

The Bosch gas flow velocity U (m / s) is expressed by the following equation (3).
^{U = V / (π · D} 2/4) ··· (3)
Here, V is the Bosch gas flow rate (m ³ / s) per tuyere, and is the gas such as oxygen-containing gas and furnace top gas blown into the raceway 30, the granular solid reducing material, and the front of the tuyere. coke cause combustion and gasification reactions in the raceway 30, CO, is a volume flow rate when converted as heated to a high temperature gas consisting of only H _2, N 2. The Bosch gas density ρf is the gas density in the above state. The Bosch gas flow rate V and the Bosch gas density ρf are the temperature, composition, flow rate of the oxygen-containing gas and the granular solid reducing material blown from the main flow hole 12, the calorific value when changing to the Bosch gas, and the pressure in the raceway 30. If you know it, you can calculate it. Further, π is the circumference ratio, and D is the inner diameter (m) of the main flow hole 12. The pressure in the raceway 30 can be replaced by a measured value obtained by installing an in-furnace pressure gauge at the height at which the tuyere 10 for the blast furnace is installed. Alternatively, the pressure in the raceway 30 may be a value obtained by calculating and subtracting the pressure loss of the flow path to the blast furnace tuyere 10 based on the original pressure of the oxygen-containing gas blown into the main flow hole 12.

In order to measure the height of the raceway 30 under various conditions, a small similarity model of 1/79 scale of the actual furnace, which is mechanically similar to the actual blast furnace, is used, and the raceway 30 is used under various conditions. Height was measured. The small similarity model, diameter instead of coke 3.44Mm, the plastic particles of density 900 kg / ^{m 3} was filled, using compressed air instead of the oxygen-containing gas. The inner diameter of the main flow hole 12 is changed in the range of 2.8 mm to 18.0 mm, and the amount of compressed air blown from the main flow hole 12 is changed in the range of 200 to 3000 L / min, and the height of the raceway 30 is changed under each condition. Was measured.

FIG. 2 is a graph showing the relationship between the Froude number (Fr) and the ratio (H / D) of the height (H) of the raceway 30 and the inner diameter (D) of the main flow hole 12. When the height H of the raceway 30 was measured under the above-mentioned conditions, as shown in FIG. 2, the Froude number shows a strong correlation with the ratio between the height of the raceway 30 and the inner diameter of the main flow hole 12. understood. From FIG. 2, the ratio (H / D) of the height of the raceway 30 and the inner diameter of the main flow hole 12 can be expressed by the following equation (4) using the Froude number.

H / D = 0.75 x Fr ^0.5 ... (4)
Here, H is the height (m) of the raceway 30 from the inner peripheral end surface of the main distribution hole 12. Further, D is the inner diameter (m) of the main distribution hole 12.

From the above equations (2), (3) and (4), the following equation (5) is derived.

H = 0.48 × {(ρf × V ² ) / (ρp × d)} ^1/4 ... (5)

In order to quickly supply the granular solid reducing material blown from the sub-flow hole 14 to the raceway 30, the main flow hole 12 is located at a distance between the centers of the discharge port of the main flow hole 12 and the discharge port of the sub-flow hole 14. The distance including half of the inner diameter D of the raceway 30 must be less than or equal to the height H of the raceway 30. Therefore, the following equation (6) is derived.

L + 1 / 2D ≦ 0.48 × {(ρf × V ² ) / (ρp × d)} ^1/4 ... (6)
Here, L is the distance (m) between the centers of the discharge port of the main flow hole 12 and the discharge port of the sub flow hole 14.

From this equation (6), the following equation (1) is derived. By providing the main flow hole 12 and the sub flow hole 14 so as to satisfy the equation (1), the granular solid reducing agent can be quickly supplied to the raceway from the sub flow hole 14. On the other hand, when the above equation (1) is not satisfied, the raceway 30 is not formed in front of the sub-flow hole 14, so that the blown granular solid reducing agent is not burned or gasified and the gap between the coke packed layers is not satisfied. I get stuck in. As a result, the granular solid reducing agent blown from the sub-flow hole 14 fuses with the coke in the coke-filled layer, causing operational troubles such as deterioration of air permeability and poor unloading.

L ≦ 0.48 × {(ρf × V ² ) / (ρp × d)} ^1/4 -1 / 2D ... (1)

Further, if the distance between the center of the discharge port of the main distribution hole 12 and the discharge port of the sub-flow hole 14 is too close, the space between the two holes penetrates, a jet is not formed in the main distribution hole 12, and the raceway 30 may not be formed. Therefore, it is preferable that the center-to-center distance L between the discharge port of the main flow hole 12 and the discharge port of the sub-flow hole 14 satisfies the following equation (7).

L> (D + E) / 2 ... (7)
Here, E is the inner diameter (m) of the sub-flow hole 14.

Further, the sub-distribution hole 14 is preferably provided directly above the main distribution hole 12, but does not have to be directly above the main distribution hole 12. Since the raceway 30 having at least the width of the inner diameter of the main flow hole 12 is formed by the main flow hole 12, the main flow hole 12 and the sub flow hole 14 can be separated from each other as long as the distance to the inner diameter of the main flow hole 12 is long. The position may shift in the circumferential direction of the blast furnace.

Since a large flow rate of oxygen-containing gas flows from the main flow hole 12 to form the raceway 30, the gas flow rate is high. Therefore, when the granular solid reducing agent is blown from the main flow hole 12, the granular solid reducing agent collides with the pipe at high speed, and the tuyere wear becomes remarkable. On the other hand, since it is not necessary to form the raceway 30 in the sub-flow hole 14, the flow velocity may be any as long as it can convey the granular solid reducing material. Therefore, by blowing the granular solid reducing material from the sub-flow hole 14, the blowing speed of the granular solid reducing material can be slowed down, so that the tuyere wear is not increased. In particular, since the maximum particle size of the waste plastic molded into pellets is about several mm, when the waste plastic is blown into the blast furnace, it cannot be blown from the main distribution hole 12 and the auxiliary distribution hole. It is essential to blow in from 14. On the other hand, when fine particles having a maximum particle size of 1 mm or less, such as pulverized coal, are used, they may be blown from the main distribution hole 12 because the wear force is not so large. However, even pulverized coal having a maximum particle size of 1 mm or less wears the tuyere, so from the viewpoint of suppressing tuyere wear, even pulverized coal is preferably blown from the sub-flow hole 14.

As shown in FIG. 1, in the blast furnace tuyere 10, the main distribution hole 12 and the sub distribution hole 14 are provided in the same tuyere, but the present invention is not limited to this, and as shown in FIG. A main flow hole and a sub flow hole may be provided in separate tuyere. FIG. 3 is a schematic cross-sectional view of the tuyere equipment 20 for a blast furnace according to another embodiment. The blast furnace tuyere facility 20 has a mainstream tuyere 22 having a main flow hole 24 for blowing a gas containing oxygen, and an auxiliary flow hole 28 installed above the mainstream tuyere 22 for blowing a granular solid reducing material. It has a sidestream tuyere 26 and.

Even in the blast furnace tuyere facility 20, in order to promptly supply the granular solid reducing agent from the sidestream tuyere 26 to the raceway 30, the raceway 30 formed by blowing oxygen-containing gas from the mainstream tuyere 22 The sidestream tuyere 26 may be provided at a position where the granular solid reducing agent can be directly blown into the furnace. That is, if the mainstream tuyere 22 and the sidestream tuyere 26 are provided so that the distance L between the center of the discharge port of the main flow hole 24 and the discharge port of the sub-flow hole 28 satisfies the above equation (1). good.

The above equation (1) is an equation in which the upper limit of L changes depending on the operating conditions such as the amount of gas from the tuyere and the type of granular solid reducing agent. Whether it is 10 or the tuyere facility 20 for a blast furnace shown in FIG. 3, the center-to-center distance L is determined and the blast furnace is installed in the blast furnace. Therefore, in reality, when the operating conditions satisfy the equation (1) with respect to the center-to-center distance L of the blast furnace tuyere 10 or the blast furnace tuyere facility 20 installed in the blast furnace, the particles are granular from the sub-flow hole. The operation is to blow in solid reducing material. Under normal operating conditions, the blast furnace tuyere 10 and the blast furnace tuyere facility 20 may be designed with the upper limit of the center-to-center distance L being about 0.5 m.

Further, the blast furnace tuyere according to the present embodiment has been described with an example in which the blast furnace tuyere 10 is applied to a general hot air blast furnace, but the present invention is not limited to this, and pure oxygen or oxygen at room temperature is described from the blast furnace tuyere 10. It may be applied to an oxygen blast furnace in which a gas containing 60% by volume or more of is blown. In particular, since the amount of Bosch gas produced is small in an oxygen blast furnace, it is necessary to narrow the tuyere diameter in order to increase the blowing speed and form the raceway 30. Therefore, in the oxygen blast furnace, the occurrence of tuyere wear and tuyere clogging due to the granular solid reducing agent becomes more remarkable than in a normal blast furnace. Therefore, it can be said that by applying the blast furnace tuyere according to the present embodiment to an oxygen blast furnace, it is possible to further suppress the occurrence of tuyere wear and tuyere clogging as compared with the case where it is applied to a normal blast furnace.

Further, it is preferable to use waste plastic having a particle size larger than 1 mm as the granular solid reducing material blown from the sub-flow hole 14. While there is a demand for waste plastics to be easily available and blown into a blast furnace in large quantities, it is difficult to crush them into fine particles. Therefore, since the waste plastic has a larger particle size and a higher wear force than the pulverized coal, the tuyere wear becomes remarkable when a large amount of the waste plastic is blown from the main distribution hole 12. On the other hand, by using the blast furnace tuyere 10 according to the present embodiment, the gas for forming the raceway 30 is blown from the main distribution hole 12 at high speed, and the waste plastic is blown from the sub-flow hole 14 into the blast furnace. Since it can be put in, tuyere wear is greatly suppressed even if a large amount of waste plastic is blown in.

Next, an example in which the blast furnace tuyere according to the present embodiment is applied to a general hot air blast furnace will be described. Table 1 shows the assumed specifications, Bosch gas, coke, and tuyere / raceway conditions of Examples and Comparative Examples.

FIG. 4 is a schematic cross-sectional view of the blast furnace 40 corresponding to Example 1, Comparative Example 1 and Comparative Example 2. In Example 1, Comparative Example 1 and Comparative Example 2, the blast furnace 40 having a pig iron output of 10000 t / d and a tuyere number of 40 was operated by applying the tuyere 10 for a blast furnace. In Example 1, oxygen blast furnace top gas (B gas) recirculated together with pure oxygen is blown from the main flow hole 12 of the blast furnace tuyere 10, and pulverized coal and waste plastic are used as granular solid reducing agents from the sub-flow hole 14. Infused. The basic unit of the pulverized coal blown in is 270 kg / t-pig, and the basic unit of the waste plastic is 30 kg / t-pig.

In Comparative Example 1, under the same operating conditions as in Example 1, pulverized coal and waste plastic of the same basic unit as in Example 1 were blown from the main distribution hole 12. Further, also in Comparative Example 2, under the same operating conditions as in Example 1, pulverized coal and waste plastic of the same basic unit as in Example 1 were blown from the sub-flow hole 14. However, in Comparative Example 2, the main distribution hole 12 and the sub-distribution hole 14 are arranged so that the distance between the center of the discharge port of the main distribution hole 12 and the discharge port of the sub-distribution hole 14 becomes long, and the main distribution hole 12 and the sub-distribution hole 14 are abolished in the raceway 30. The position was set so that plastic could not be blown. Comparative Example 2 does not satisfy the above formula (1).

Using the above-mentioned small similarity model of 1/79 scale of the actual furnace, under these conditions, the colored fine particle plastic with a diameter of 1.0 mm can be transferred to the sub-flow hole 14 or the main at an air flow transport rate of 3.6 m / sec. A test of blowing through the flow hole 12 was carried out. The fine particle plastic that was blown in was photographed with a high-speed camera, and its behavior was scrutinized. As a result, in Comparative Example 1, the fine particle plastic could be supplied to the raceway 30. However, since the blowing speed of the gas blown from the main flow hole 12 is faster than the airflow transport speed of the fine particle plastic in order to stably form the raceway 30, the fine particle plastic is used in the main flow hole 12. It was colliding with the inner wall of the car at high speed. This collision causes tuyere wear in the actual machine. Therefore, it can be seen that the tuyere wear cannot be suppressed in Comparative Example 1.

Further, in Comparative Example 2, it was confirmed that the fine particle plastic blown from the sub-flow hole 14 could not be blown into the raceway 30, and the fine particle plastic stagnated in the vicinity of the sub-flow hole 14. In this state, the air permeability in the furnace deteriorates in the actual machine. In addition, the blown fine particle plastic is not completely burned and the combustion rate is lowered, so that it cannot contribute to energy saving in the ironmaking process.

On the other hand, in Example 1, the fine particle plastic can be supplied to the raceway 30, and the fine particle plastic is conveyed at the air flow transport speed in the sub-flow hole 14, so that the fine particle plastic does not collide with the pipe at high speed. .. From these results, in Example 1, there is no concern about deterioration of air permeability in the furnace and decrease in the combustion rate of the blown fine particle plastic, and there is no concern about increase in tuyere wear and tuyere clogging. confirmed.

FIG. 5 is a schematic cross-sectional view of the blast furnace 50 corresponding to Example 2, Comparative Example 3, and Comparative Example 4. In Example 2, Comparative Example 3 and Comparative Example 4, the blast furnace tuyere equipment 20 was applied to the blast furnace 50 having a pig iron output of 10000 t / d and 40 tuyere ports for operation. In Example 2, oxygen-enriched hot air was blown from the main flow hole 24 of the main stream tuyere 22, and pulverized coal and waste plastic were blown from the sub flow hole 28 of the side stream tuyere 26 as a granular solid reducing agent. The basic unit of the pulverized coal blown in is 140 kg / t-pig, and the basic unit of the waste plastic is 10 kg / t-pig.

In Comparative Example 3, under the same operating conditions as in Example 2, pulverized coal and waste plastic of the same basic unit as in Example 2 were blown from the main distribution hole 24 of the mainstream tuyere 22. Further, also in Comparative Example 4, under the same operating conditions as in Example 2, pulverized coal and waste plastic of the same basic unit as in Example 2 were blown from the secondary distribution hole 28 of the sidestream tuyere 26. However, in Comparative Example 4, the mainstream tuyere 22 and the sidestream tuyere 26 are arranged on the raceway 30 so that the distance between the centers of the discharge port of the main flow hole 24 and the discharge port of the sub-flow hole 28 becomes long. The position was set so that waste plastic could not be blown. Comparative Example 4 does not satisfy the above formula (1).

Under these conditions, using the small similarity model described above, a test was conducted in which colored fine particle plastic with a diameter of 1.0 mm was air-transported at a speed of 3.6 m / sec and blown from the mainstream tuyere 22 or the sidestream tuyere 26. gone. The fine particle plastic that was blown in was photographed with a high-speed camera, and its behavior was scrutinized. As a result, in Comparative Example 3, the fine particle plastic could be supplied to the raceway 30. However, since the blowing speed of the gas blown from the main flow hole in order to form the raceway 30 is faster than the airflow transport speed of the fine particle plastic, it seems that the fine particle plastic collides with the pipe at high speed. confirmed. This collision causes tuyere wear in the actual machine. Therefore, in Comparative Example 3, it can be seen that tuyere wear cannot be suppressed.

Further, in Comparative Example 4, it was confirmed that the fine particle plastic blown from the sidestream tuyere 26 could not be blown into the raceway 30, and the fine particle plastic stagnated in the vicinity of the sidestream tuyere 26. In this state, the air permeability in the furnace deteriorates in the actual machine. In addition, the blown fine particle plastic is not completely burned and the combustion rate is lowered, so that it cannot contribute to energy saving in the ironmaking process.

On the other hand, in the second embodiment, the fine particle plastic can be supplied to the raceway 30, and the fine particle plastic is conveyed at the air flow transport speed in the sub-flow hole 28, so that the fine particle plastic does not collide with the pipe at high speed. .. From these results, in Example 2, there is no concern about deterioration of air permeability in the furnace, decrease in the combustion rate of the blown fine particle plastic, and there is no concern about increase in tuyere wear or tuyere clogging. confirmed. From the above, by using the blast furnace tuyere 10 or the blast furnace tuyere equipment 20 according to the present embodiment, the raceway 30 can be used without causing wear of the tuyere, increase in tuyere clogging, or deterioration of air permeability. It was confirmed that a large amount of granular solid reducing material could be supplied.

10 Blast furnace tuyere 12 Main distribution hole 14 Secondary distribution hole 20 Blast furnace tuyere equipment 22 Mainstream tuyere 24 Main distribution hole 26 Secondary flow tuyere 28 Sub-distribution hole 30 Raceway 40 Blast furnace 50 Blast furnace

Claims (4)

A method of blowing a granular solid reducing agent into a blast furnace using a tuyere for a blast furnace.
The blast furnace tuyere has a main distribution hole for blowing a gas containing oxygen into the blast furnace, and
A sub-flow hole installed above the main flow hole and for blowing the granular solid reducing agent,
Have,
Assuming that the distance between the centers of the discharge port of the main flow hole and the discharge port of the sub flow hole is L, the gas is blown into the blast furnace from the main flow hole so as to satisfy the following equation (1) and the raceway. A method for blowing a granular solid reducing agent, in which the granular solid reducing material is blown from the secondary flow hole while forming the above.
L ≦ 0.48 × {(ρf × V ² ) / (ρp × d)} ^1/4 -1 / 2D ... (1)
In the above equation (1), L is the distance (m) between the centers of the discharge port of the main flow hole and the discharge port of the sub flow hole, ρf is the Bosch gas density (kg / m ³ ), and V. Is the bosh gas flow rate per tuyere (m ³ / s), ρp is the apparent density of coke in front of the discharge port of the main flow hole (kg / m ³ ), and d is the particle size of the coke (m). ), And D is the inner diameter (m) of the main flow hole. It is a method of blowing a granular solid reducing agent into a blast furnace using a tuyere facility for a blast furnace.
The blast furnace tuyere facility includes a mainstream tuyere having a main distribution hole for blowing a gas containing oxygen into the blast furnace.
A sidestream tuyere that is installed above the mainstream tuyere and has a secondary flow hole for blowing the granular solid reducing agent.
Have,
Assuming that the distance between the centers of the discharge port of the main flow hole and the discharge port of the sub flow hole is L, the gas is blown into the blast furnace from the main flow hole so as to satisfy the following equation (1) and the raceway. A method for blowing a granular solid reducing agent, in which the granular solid reducing material is blown from the secondary flow hole while forming the above.
L ≦ 0.48 × {(ρf × V ² ) / (ρp × d)} ^1/4 -1 / 2D ... (1)
In the above equation (1), L is the distance (m) between the centers of the discharge port of the main flow hole and the discharge port of the sub flow hole, ρf is the Bosch gas density (kg / m ³ ), and V. Is the bosh gas flow rate per tuyere (m ³ / s), ρp is the apparent density of coke in front of the discharge port of the main flow hole (kg / m ³ ), and d is the particle size of the coke (m). ), And D is the inner diameter (m) of the main flow hole. The method for blowing a granular solid reducing agent according to claim 1 or 2 , wherein the gas containing oxygen is a gas containing 60% by volume or more of oxygen. Wherein the particulate solid reducing material is a waste plastic, blow method of the particulate solid reducing material according to any one of claims 1 to 3.

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