JPH08260007A - Simultaneous blowing operation of pulverized coal and waste plastic in blast furnace - Google Patents

Abstract

(57) [Abstract] [Purpose] Promote the combustion of waste plastic blown from the tuyere, achieve complete combustion within the raceway, ensure the air permeability of the blast furnace, and maintain the production volume and fuel ratio. . [Structure] 50 to 50 of waste plastic blowing position
Blow pulverized coal from 0 mm before. Further, the pulverized coal blowing position and / or the waste plastic blowing amount is adjusted according to the volatile matter content of the pulverized coal. [Effect] 1500-2 formed by blowing pulverized coal
By blowing the waste plastic into the temperature field of the high temperature atmosphere of 000 ° C., the combustion promotion of the waste plastic is promoted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention, when blowing waste plastic from the tuyere of a blast furnace, ensures the combustibility of the waste plastic to maintain the air permeability of the blast furnace, improving the productivity and improving the fuel ratio. The present invention relates to a blast furnace operating method for reducing and solving a waste plastic treatment problem.

[0002]

2. Description of the Related Art In blast furnace operation, as an alternative to coke, an inexpensive fuel with good combustibility and high calorific value (pulverized coal, petroleum, heavy oil, naphtha, etc.) is blown from the tuyere to reduce the hot metal production cost. , Is trying to improve productivity,
The technology is disclosed in Japanese Patent Publication No. 23763. In particular, the injection of pulverized coal has become the mainstream in recent years from the viewpoint of price, which greatly contributes to reduction of fuel ratio (cost reduction) and improvement of productivity.

The pulverized coal thus blown burns in the blast furnace instead of a part of the coke, and because of its good combustibility and high calorific value, it produces a large amount of reducing gas at high temperature and is efficient. Various reduction reactions. Therefore, the iron ore charged from the furnace top is quickly reduced to a metal state and is melted to form high-temperature hot metal, so that the furnace heat of the blast furnace is high and the productivity is improved.

On the other hand, there is a large amount of waste plastics in municipal wastes or industrial wastes, and in reality, there is no treatment method other than the wastes that are sent to landfill as difficult-to-treat wastes. If this waste plastic can be recycled as resources, it will lead to the reduction of municipal waste, and if it can be effectively used as fuel, it will lead to energy saving. If it can be safely treated, it will be a pollution-free treatment technology.

[0005]

By the way, in the conventional blast furnace operation, the operation of blowing the waste plastic from the tuyere is not performed, but since the particle size is large and the ignitability is poor as compared with pulverized coal, Unburned, it enters the blast furnace combustion zone (raceway) into the blast furnace (lower dropping zone and core) and accumulates in the furnace due to the large particle size, which improves the air permeability of the blast furnace and the liquid permeability of the molten pig iron. There is a possibility that it will hinder the production of blast furnaces. Therefore, there seems to be an upper limit to the amount of waste plastic blown.

The term "waste plastic" as used in the present invention refers to a material obtained by crushing a material such as an electric wire coating material, a PET bottle, and a residual material which is melted for recycling into 10 mm or less in industrial waste. Therefore, the present invention improves the combustibility of the waste plastic, and eliminates the waste plastic that enters the lower dropping zone and the core from the raceway of the blast furnace while remaining unburned, thereby canceling the upper limit of the waste plastic blowing amount. The purpose is to secure ventilation and liquid permeability of the blast furnace and maintain the production volume and fuel ratio.

[0007]

Means for Solving the Problems The present invention is to solve the above problems, in which iron ore and coke are alternately charged in layers from the top of a blast furnace, and auxiliary fuel is supplied from a lance installed at the tuyere. In the operating method of the blast furnace, the waste plastic is blown from the waste plastic blowing lance installed on the air duct of the tuyere, and it is installed 50 to 500 mm before the waste plastic blowing position in the air blowing direction of the air duct. It is characterized in that pulverized coal is blown from the pulverized coal blowing lance.

Further, the position of the lance for blowing pulverized coal is adjusted within the range of the following formula (1) according to the content of the volatile component of the pulverized coal blown from the tuyere. When the volatile matter content of pulverized coal,% ≧ 40: (Position of the lance for blowing pulverized coal, mm) ≧ 50 (When the volatile matter content of pulverized coal,%) <40: ( Position of lance for blowing pulverized coal, mm) ≧ 450-10 × (content of volatile component of pulverized coal,%) (1)

Further, the amount of the waste plastic blown from the waste plastic blowing lance is adjusted within the range of the formula (2) according to the content of the volatile component of the pulverized coal blown from the tuyere. To do. (Content of volatile matter of pulverized coal,%) ≧ 10: (amount of waste plastic blown, kg / t) ≦ 2 × (content of volatile matter of pulverized coal,%) (volatile matter of pulverized coal When content,%) <10: (amount of waste plastic blown, kg / t) ≦ 20 (2)

[0010]

In the present invention, the pulverized coal blowing position is set before the blowing position of the waste plastic. That is, FIG. 1 is a cross-sectional view of the tuyere of the blast furnace, in which waste plastic and pulverized coal are blown from the lance inserted from the side wall of the blower branch pipe 2 attached to the tuyere 1, but the waste plastic blowing lance 3 is used. And the lance 4 for blowing pulverized coal,
As shown in FIG. 1, the blowing position is shifted and installed. FIG. 1
5 is an iron skin and 6 is a brick.

Usually, the temperature of the hot air blown from the tuyere of the blast furnace is about 1200 to 1250 ° C., and even if a waste lance is blown into this temperature field by inserting a lance from the side wall of the blast branch pipe, the grain size is large. Due to poor ignitability, desorption of volatile components in the waste plastic does not proceed, resulting in poor flammability. For this reason, the combustion progresses slowly even if it enters the raceway, and it is released outside the raceway in an unburned state.

On the other hand, since pulverized coal has a fine particle size and good ignitability, when a lance is inserted from the side wall of the blast branch pipe and blown into a temperature field of 1200 to 1250 ° C, desorption of volatile components proceeds. Then, the combustibility becomes good, and the temperature of the blown atmosphere rises to 1500 to 2000 ° C. As a matter of course, the combustion progresses quickly even when entering the raceway,
It will not be released outside the raceway unburned. In the present invention, 1500 to 2000 formed by pulverized coal blown from before the waste plastic blowing position
By blowing waste plastic into the temperature field of ℃,
Due to the high temperature, the desorption of volatile components from the waste plastic progresses and the combustibility is improved. The combustion progresses quickly even when entering the raceway, and the waste plastic is released outside the raceway without burning. Disappears.

The pulverized coal blowing lance preferably has a pulverized coal blowing lance 50 to 500 mm in front of the waste plastic blowing lance. At a position of less than 50 mm, the atmospheric temperature near the blowing position due to the combustion of pulverized coal is not sufficiently raised, and the effect of promoting waste plastic combustion is small. Again 50
If it exceeds 0 mm, the temperature rise is sufficient and the effect of promoting waste plastic combustion is large, but it is structurally difficult to install a lance to be inserted into the side wall of the blower branch pipe, which is not practical.
The pulverized coal blowing position is changed by adjusting the amount of the pulverized coal blowing lance installed in the blast branch pipe of the tuyere into the blast branch pipe.

Further, the progress of desorption of volatile matter differs depending on the volatile matter content of the pulverized coal, and the ambient temperature near the blowing position differs, which affects the combustion of the waste plastic blown later. Therefore, in the present invention, the pulverized coal blowing position is adjusted according to the volatile matter content of the pulverized coal. FIG. 2 shows the relationship between the volatile matter content of the pulverized coal and the pulverized coal injection position before the waste plastic injection position, which are found by the present invention. In FIG. 2, as the volatile matter content of the pulverized coal increases, the desorption of the volatile matter proceeds, so the combustion of the volatile matter is promoted, and the temperature of the blown atmosphere rises further. Therefore, the pulverized coal blowing position before the waste plastic blowing position may have a short distance. Figure 2
The distance shown in indicates the minimum required distance, 50 to 500 mm
The distance may be long as long as the distance is between.

Further, in order to eliminate the influence on the combustion of the waste plastic blown afterward, the progress of desorption of volatile matter differs depending on the volatile content of the pulverized coal, and the ambient temperature near the blowing position differs. In the present invention, the amount of waste plastic blown is adjusted according to the volatile matter content of the pulverized coal. FIG. 3 shows the relationship between the volatile matter content of pulverized coal and the amount of waste plastic injected, which was found by the present invention.
Shown in In FIG. 3, as the content of volatile matter in the pulverized coal increases, desorption of the volatile matter proceeds, so that the combustion of the volatile matter is promoted and the temperature of the blown atmosphere is further increased. Therefore, the amount of waste plastic blown can be increased. The amount of waste plastic blown in shown in FIG. 3 shows the maximum value, and if it is less than this value, any amount can be blown.

Further, in the present invention, the combustibility of the waste plastic is further promoted by adjusting both the pulverized coal injection position and the waste plastic injection amount according to the volatile matter content of the pulverized coal. When a problem occurs in the air permeability of the blast furnace, the air permeability can be improved by adopting the method of the present invention.

[0017]

EXAMPLES The features of the present invention will be specifically described with reference to the following examples. Table 1 shows the operation results. (Example 1) Volatile content 32%, average particle size 0.10 m
For the operation in which pulverized coal (m) was blown at 155 kg / t (per ton of hot metal), the blown wire was crushed to 10 mm or less as the waste plastic. The minimum required value for blowing pulverized coal with respect to the waste plastic blowing position shown in FIG. 2 is 130 mm, and the maximum amount of waste plastic blowing shown in FIG. 3 is 65 kg / t. Place the pulverized coal injection position before the waste plastic injection position 15
Installed at 0 mm (at this time, the temperature of the blown atmosphere is 1
700 ° C), the amount of waste plastic blown is 35k
This is an example of operation with g / t. In comparison with Comparative Example 1 described later, the blast pressure indicating the air permeability of the blast furnace is low, the amount of tapped iron is large, and the fuel ratio is low.

(Example 2) Pulverized coal having a volatile content of 15% and an average particle size of 0.08 mm was blown at 130 kg / t (per ton of hot metal), while a plastic bottle was crushed to 8 mm or less as waste plastic. What was done was carried out. The minimum required value of pulverized coal injection for the waste plastic injection position shown in FIG. 2 is 300 mm.
The maximum amount of waste plastic blown in is 30 kg / t. This is an example of operation in which the pulverized coal blowing position is set 350 mm before the waste plastic blowing position (the temperature of the atmosphere blown at this time is 1850 ° C.) and the waste plastic blowing amount is 20 kg / t. Compared with Comparative Example 2 described later, the blast pressure showing the air permeability of the blast furnace is low, the amount of tapped iron is large, and the fuel ratio is low.

[0019]

[Table 1]

In Comparative Example 1, 155 kg / t of pulverized coal having a volatile content of 32% and an average particle size of 0.10 mm and a wire coating material as waste plastic crushed to 10 mm or less 3
This is an example of operation in which 5 kg / t was blown from the same lance. Compared to Example 1, the blowing pressure is high, the amount of tapping is small, and the fuel ratio is high. Comparative Example 2 has a volatile content of 15
%, 130 kg / t of pulverized coal having an average particle size of 0.08 mm and 20 kg / t of a plastic bottle crushed to 8 mm or less as waste plastic are blown from the same lance. Compared with Example 2, the blowing pressure is high, the amount of tapped iron is small, and the fuel ratio is high.

[0021]

As described above, in the present invention, when blowing waste plastic, pulverized coal is blown from before the blowing position to form a high temperature atmosphere of 1500 to 2000 ° C. By blowing waste plastic into the field, it is possible to accelerate the combustion of waste plastic and achieve complete combustion within the raceway. In addition, the waste plastic is completely burned by performing detailed operations by adjusting the pulverized coal injection position and the waste plastic injection amount according to the volatile matter content of the pulverized coal. As a result, blast furnace air permeability can be secured, production can be increased, and a low fuel ratio can be maintained.

[Brief description of drawings]

FIG. 1 is a sectional view of a tuyere of a blast furnace for explaining a method for carrying out the present invention.

FIG. 2 is a diagram showing a relationship between a volatile matter content of pulverized coal and a pulverized coal injection position before a waste plastic injection position when the present invention is carried out.

FIG. 3 is a diagram showing the relationship between the volatile content of pulverized coal and the amount of waste plastic blown when the present invention is carried out.

[Explanation of symbols]

 1 Tuyers 2 Blower branch pipe 3 Waste plastic blowing lance 4 Pulverized coal blowing lance 5 Iron crust 6 Brick

Claims (3)

[Claims] 1. A method for operating a blast furnace in which iron ore and coke are alternately charged in layers from the top of a blast furnace and auxiliary fuel is blown from a lance installed at the tuyere, which is installed at a blower branch pipe at the tuyere. Waste plastic is blown from the waste plastic blowing lance, and pulverized coal is blown from the pulverized coal blowing lance which is installed 50 to 500 mm before the waste plastic blowing position in the blowing direction of the blower branch pipe. Method for Simultaneous Injection of Pulverized Coal and Waste Plastic in a Blast Furnace. 2. The position of the lance for blowing pulverized coal is set according to the following (1) according to the content of volatile matter in the pulverized coal blown from the tuyere.
The method for simultaneously blowing pulverized coal and waste plastic in a blast furnace according to claim 1, wherein the method is adjusted within the range of the formula. When the volatile matter content of pulverized coal,% ≧ 40: (Position of the lance for blowing pulverized coal, mm) ≧ 50 (When the volatile matter content of pulverized coal,%) <40: ( Position of lance for blowing pulverized coal, mm) ≧ 450-10 × (content of volatile component of pulverized coal,%) (1) 3. The amount of waste plastic blown from the waste plastic blowing lance is adjusted within the range of the following formula (2) according to the content of volatile components of the pulverized coal blown from the tuyere. The method for simultaneously blowing pulverized coal and waste plastic in a blast furnace according to claim 1 or 2. (Content of volatile matter of pulverized coal,%) ≧ 10: (amount of waste plastic blown, kg / t) ≦ 2 × (content of volatile matter of pulverized coal,%) (volatile matter of pulverized coal When content,%) <10: (amount of waste plastic blown, kg / t) ≦ 20 (2)