JPH0343220Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The invention relates to the structure of a blast furnace tuyere.
This prevents melting of the heat insulating ring attached to the inner surface of the tuyere and further improves the heat insulating effect, and is used in blast furnace tuyeres for pulverized coal injection operations, etc.

(Conventional tuyere structure) As for fuel injection in blast furnace operations, due to the effects of soaring oil prices, heavy oil injection has been overshadowed, and all-coke operation has become mainstream.

Recently, injection of pulverized fuel such as pulverized coal has been frequently implemented in order to alleviate the difficulty of all-coke operation and to save expensive coke.

However, pulverized coal and other pulverized fuels (hereinafter simply referred to as pulverized fuels) have disadvantages in that they have a slower combustion rate than heavy oil and contain unburned matter such as ash.

In other words, in conventional heavy oil injection in which the tip of the burner is placed near the boundary point between the blast furnace tuyere and the blow pipe, the injected fuel is not completely burned out in the raceway immediately after the blast furnace tuyere. I can't do it,
As a result, the combustion rate deteriorates.

In addition, powdered fuel contains a small amount of ash to varying degrees, and this ash melts due to the heat of combustion, but this molten material collides with the inner surface of the blow pipe and adheres to and accumulates there. This not only makes it difficult to continue the stable injection of fuel, but also makes the blowing of hot air from the blast furnace tuyeres unstable. As a result of various investigations, the applicant discovered that, as in the invention previously filed (Registration No. 1376420, Japanese Patent Publication No. 60-53081), the location of the powder fuel injection burner is within the blow pipe, and the blow pipe and blast furnace blade are 100-350mm upstream from the border with the mouth (optimal position 200-350mm)
We attempted to solve the problem by injecting fuel at a position of 350mm).

As mentioned above, the optimal injection position of powdered fuel has been solved, but there are some problems such as heat loss at the blast furnace tuyere or melting of the insulation ring attached to the inner surface of the tuyere. has become apparent.

That is, as shown in Fig. 4, the blast air from the blow pipe 2 reaches a temperature of approximately 1050 to 1200°C and is blown into the furnace through the blast furnace tuyere 3. A water cooling chamber 5 for high-speed flow of cooling water is installed inside for the purpose of extending the life of the cooling water itself, and a fourth
As shown in the figure, the entire inner surface of the tuyere is coated with heat insulating material (insulating ring 4
It is commonly installed as ) has been done.

The heat loss at the blast furnace tuyere 3 is slightly improved by coating the inner surface with a heat insulating material, but the material used for the heat insulating material is the same as the refractory used in the blast furnace (for example, refractory bricks, refractory mortar, castable refractories, etc.). may be done.

Furthermore, in addition to the above-mentioned heat-insulating coating made of a refractory material, there are also those in which the heat-insulating ring is made of a metallic material (for example, a high-alumina material) that does not react with the ash in the powdered fuel.

(Problems to be solved by the invention) As mentioned above, when injecting powdered fuel into the blast furnace, the blow pipe 2 of the powdered fuel injection burner 1
By setting the installation position upstream, in other words, 100 to 350 mm from the boundary between the blast furnace tuyere 3 and the blow pipe 2, the molten powder fuel collides with and adheres to the inner peripheral surface of the blow pipe 2. However, it has also been found that improving the heat insulation effect of powdered fuel, especially at the blast furnace tuyere in all-coke operation, is an important factor in this type of technology.

This is because, as described above, the blast furnace tuyere 3 is equipped with a water cooling mechanism inside the tuyere to protect the tuyere, and a blow pipe connected to the tuyere The hot air from the
For example, the temperature is approximately 1200°C, and for this reason, with the intention of further protecting the blast furnace tuyere, a heat insulating ring made of refractory or metallic material is installed to increase the heat insulation effect.

However, problems caused by attaching this heat insulating ring 4 have also become apparent.

That is, when the constituent material of the heat insulating ring 4 attached to the inner surface of the tuyere is a refractory material, the ash in the powdered fuel and the composition of the refractory material react, and a product is produced on the downstream side b of the insulating ring (this There have been accidents in which the ring has adhered to the tip of the tuyere (the downstream side refers to the tip side of the tuyere), or the ring has been melted and damaged by the low melting point compound. (Refer to Figure 5) When the material of the heat insulating ring is made of metal, if the material has a high thermal conductivity, the heat insulating effect will be small; on the other hand, if the thermal conductivity is low, the cooling Since the effect is inhibited, defects occur that are melted away by the high temperature flame of the pulverized coal of the powdered fuel.

Based on the above knowledge, the erosion of the heat insulating ring occurs at the downstream side of the tuyere.

Therefore, in pulverized fuel, especially pulverized coal injection operations, it is important not only to set the pulverized coal injection position (combustion efficiency, ash deposition rate), but also to adjust the blast air from the blow pipe 2 through which the pulverized coal fuel is sent. It is necessary to blow air into the blast furnace without heat loss.

Specifically, the goal is to avoid accidents such as melting of the insulation ring at the blast furnace tuyere and to have a high insulation effect.

(Means for solving the problems) Based on the above-mentioned viewpoint, as a means to solve the problems in the conventional blast furnace tuyere, it is necessary to prevent melting of the heat insulating ring attached to the inner surface of the blast furnace tuyere and to In order to increase the effect, the structure of the blast furnace tuyere is connected to a blow pipe that delivers powdered fuel injected from a powdered fuel injection burner and hot air from a hot blast furnace, and cooling water is circulated inside. In the blast furnace tuyere, the length of the heat insulating ring is 220 mm toward the downstream side from the boundary position between the blow pipe and the blast furnace tuyere. It is designed to be installed within a range of 150 mm to 150 mm, and attempts to solve the problem.

The tuyere structure of the present invention is as described above, but the reason why the installation length of the insulation ring is set to 220 mm to 150 mm is as follows.
It is as follows.

Regarding the appropriate range of the heat insulating ring to be installed on the inner surface of the blast furnace tuyere, we focused on this point because it is caused by the adhesion and accumulation of ash in the powdered fuel, which causes melting damage, and conducted experiments and tests in actual blast furnace operation. Because the investigation was difficult, a simulated device was used.

That is, an apparatus with the related structure shown in the schematic diagram shown in Fig. 1 was used, and the experimental conditions were as follows: Powder fuel: Volatile content: 20-45% by weight Powder injection amount: 100 Kg/hour Injection speed: 10-25 Nm/sec Transportation fuel solid-air ratio: 5-25Kg/Kg Hot air temperature: Approximately 1200℃ Same pressure: 200mmAq Same tuyere tip flow velocity: 250m/sec Blow pipe diameter: 130mm-180mm Tuyere diameter: 120mm Tuyere length: 500mm (However, (including the tuyere socket), and measured the range in which ash content in the powdered fuel did not adhere to the insulation ring and the combustibility was good.

As mentioned above, Fig. 1 simulates the relationship between the position of the pulverized fuel injection burner and the length of the heat insulating ring.
is the upstream side from the boundary position a where the burner passes through and connects the blow pipe 2 located at the center of the flow path and the blast furnace tuyere 3 (here, the upstream side refers to the direction toward the blast furnace tuyere 3). 100mm to 350mm to the downstream side, and conversely, the direction away from the tuyere is the upstream side.
When the ring was installed at a position of mm (preferably 200 mm to 350 mm) (l ₁ ) and the relationship with the position of ash adhesion on the heat insulating ring 4 was investigated, the results shown in the graph of FIG. 2 were obtained.

The graph in the same figure shows blow pipe 2 and blast furnace tuyere 3.
The connection point with the is the boundary position (point a), the horizontal axis is the position of the fuel injection burner from this point at a distance of 0 mm to 350 mm (l ₁ ), and the vertical axis is the installation of the insulation ring 4. This figure shows the melting loss of the heat insulating ring 4 and the adhesion of ash in the range (l ₂ ).

As can be seen from the same graph, the installation range in which insulation ring 4 did not melt was 280 mm to 150 mm (), but this is related to the position of fuel injection burner 1 (as mentioned above, 100 to 350 mm is optimal). From this perspective, the optimal burner position is between 200 mm and 350 mm (area of the same graph), where the risk of ash adhesion and accumulation is minimal.

In other words, the range corresponding to the area ( ) (hatched area) where there is no melting damage of the heat insulating ring 4 and no adhesion/accumulation of ash in the powdered fuel, that is, the mounting range of the heat insulating ring 4 is 220 mm to 150 mm, preferably 200mm~180
It was found that by setting the diameter to mm, there was no melting loss of the heat insulating ring and the heat insulating effect was large.

Therefore, the installation range of the heat insulating ring on the inner surface of the blast furnace tuyere was set to be 220 mm to 250 mm.

In addition, the position of fuel injection burner 1 should be adjusted from 100mm to 350mm.
The reason why mm was chosen as optimal is that the same applicant applied first,
This is based on the knowledge of the prior application (Registration No. 1376420), and the detailed reason will be omitted.

(Example) Although the present invention is as described above, an example thereof will be explained based on FIG. 3.

FIG. 3 is an enlarged sectional view of the blast furnace tuyere 3. The entire tuyere is usually made of pure copper, and in order to extend the life of the tuyere itself, a high-speed flow of cooling water and multiple water cooling chambers 5 are formed inside. , its length is about 500 in total
In addition to being configured to have a length of mm, a fuel blowing port 6 with a diameter of 120 mm is bored through the inner surface.

The inner circumferential surface of the tuyere 3 facing the air outlet 6 is made of high alumina (generally Al ₂ O ₃ 93-96%, SiO ₂ 3
~5%, Fe ₂ O ₃ 0.2~0.5% and other components)
The heat insulating ring 4 made of
It was configured to be installed over a range of 200 mm downstream from the junction point between 2 and the blast furnace tuyere 3 (indicated by a dashed line in FIG. 3), that is, the boundary position (point a) between the two.

Next, for the tuyere in this example, the insulation effect was determined on the temperature of the waste water inside the cooling chamber 5, and when comparing the case where the insulation ring 4 was installed in the tuyere 3 and the case where it was not installed, it was found that approximately There was a temperature difference of 3°C.

That is, when the water supply temperature was 30°C, depending on whether or not the heat insulating ring 4 was installed, the drainage temperature was 30.5°C when it was installed, and 33.5°C when it was not installed.

Therefore, the difference in wastewater temperature is 3°C, which, when converted into heat quantity, is the result of suppressing heat dissipation by 25°C due to wind temperature.

(Effects of the invention) As described above, the tuyere structure of the invention has a mounting range of the mounting ring on the inner peripheral surface of the tuyere of 220 mm to 150 mm downstream from the boundary between the blow pipe and the blast furnace tuyere.
Since the structure is such that the ring is installed within the area, there is no erosion of the insulation ring itself, and since the ash in the powdered fuel can be deposited, it has a high insulation effect with no heat loss from the hot air sent from the blow pipe. can do.

Therefore, in addition to being able to stably inject fuel, it can also greatly contribute to stable blast furnace operation.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the relationship between the position of the powder fuel injection burner and the length of the insulation ring of the tuyere, and Figure 2 is a diagram showing the relationship between the length of the insulation ring and the distance between the position of the powder fuel injection burner. Graph showing the relationship between heat insulating ring erosion and ash adhesion; Figure 3 is an enlarged sectional view of a blast furnace tuyere that is an embodiment of the present invention; Figure 4 is a sectional view showing a conventional tuyere structure; The figure is a sectional view showing the melted portion of the heat insulating ring. The name of the code is as follows. 1...Powdered fuel injection burner, 2...Blow pipe, 3...Blast furnace tuyere, 4...Insulation ring, 5...Cooling water chamber, point a...
…Joining boundary position between blast furnace tuyere and blow pipe, l ₁
...Distance from the boundary position to the burner position, l ₂ ...
Length of insulation ring.

Claims (1)

[Scope of utility model registration request] It is connected to a blow pipe that supplies powdered fuel injected from a powdered fuel injection burner and hot air from a hot blast furnace, forming a cooling chamber through which cooling water flows, and the inner surface is insulated with heat insulating material. A blast furnace tuyere equipped with a ring is characterized in that the length of the heat insulating ring is installed in a range of 220 mm to 150 mm downstream from the boundary between the blow pipe and the blast furnace tuyere. Structure of blast furnace tuyere.