JPS62263906A - Method for blowing pulverized coal from blast furnace tuyere - Google Patents

Abstract

PURPOSE:To decrease the amt. of the costly coke for a blast furnace to be used and to stabilize a blast furnace operation by forming a pulverized coal blowing nozzle at the tuyere of the blast furnace into specific double constructions for the pulverized coal and oxygen and blowing a specific amt. or above of the pulverized coal by said nozzle. CONSTITUTION:The pulverized coal blowing nozzle 11 provided in the tuyere 1 of the blast furnace is constituted of the pulverized coal blowing part 12 and the oxygen blowing part 13 formed on the outside thereof and is horizontally installed in a blast branch pipe 3 for hot wind. The top end of the oxygen blowing part 13 is closed and is provided with blowing holes 16 at 3 points. The pulverized coal of >=150kg per ton of a molten iron is blown at >=30% oxygen concn. during blasting while the distance between the top end of the pulverized coal blowing nozzle made into the double construction for the pulverized coal and oxygen and the top end of the blast furnace tuyere is maintained at <=300mm. The use amt. of the costly coke for the blast furnace to be supplied from the blast furnace top is reduced and the cost of producing the molten iron is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method of injecting pulverized coal from a blast furnace tuyere.

(Prior Art) In recent years, in blast furnace operation, a method has been adopted in which pulverized coal is injected from the blast furnace tuyere in a highly oxygen-enriched state using hot air.

In this case, as shown in FIG. 4, the pulverized coal is blown obliquely into the blast branch pipe section and carried into the raceway by hot air. However, in such a method, since there is a considerable distance from the injected position to the tip of the blast furnace tuyere 1 and the inside of the raceway, in some cases, the injection may come into contact with the inside of the blast furnace tuyere 1, or In some cases, the coal burns before reaching the raceway, and its ash accumulates in the blast furnace tuyere 1, impeding the blowing of air and the injection of pulverized coal.

In addition, in FIG. 4, 2 is a pulverized coal injection nozzle, 3 is a blowing branch pipe, and 4 is an iron shell.

Furthermore, enrichment of oxygen was conventionally carried out in the blast pipe at the inlet of the hot air stove, so that after the oxygen was heated to about 1000° C. or higher in the hot blast furnace, it was blown in from the blast pipe. Therefore, in such a method of enriching oxygen at the inlet of a hot air stove, there is a safety limit to the amount of oxygen enriched, and the oxygen enrichment is only a few percent at most.

Therefore, as a means for solving the former of these problems, Japanese Utility Model Application Publication No. 61-24449 has been disclosed. In this method, the main body of the lance is horizontally buried in the lining of the blowpipe through a protective tube, and the discharge port at the tip of the lance is placed in the direction of the blast furnace tuyere so that the direction of injection approximately coincides with the axis of the blast furnace tuyere. It is characterized in that it opens at the same time.

(Problems to be Solved by the Invention) The device disclosed in the above-mentioned Utility Model Application Publication No. 61-24449 is a useful device that can solve the former problem, but the injection of pulverized coal in these conventional methods is limited to 150% at most. kg/P
, T, and was intended solely to maintain heat balance in the circumferential direction of the blast furnace.

For this reason, pulverized coal has only been blown in using an inert gas such as CO□ or N2 as a carrier gas, and oxygen enrichment has not been carried out at the relevant portions.

Furthermore, the latter oxygen enrichment was limited to a few percent in order to improve the productivity of the blast furnace and for safety reasons.

The present invention has been made in view of these problems,
The purpose is to provide a method for injecting pulverized coal from the blast furnace tuyere, which can reduce the unit consumption of coke charged from the top of the furnace and replace it with low-quality pulverized coal.

That is, coke charged from the top of the furnace uses expensive coking coal as a raw material and requires 15 to 30 hours to coke, resulting in a high cost of the coke obtained.

On the other hand, the pulverized coal injected from the blast furnace tuyere does not need to be of special quality, and cheap, low-grade, non-caking coal can be used and does not need to be processed into coke. That's because there isn't.

The reason why expensive coking coal is used as a raw material for coke is that the coke is charged from the top of the furnace together with raw materials such as ore, so it must be maintained at a certain level of strength to prevent the coke from pulverizing. This is because stable blast furnace operation cannot be achieved if the coke becomes powder.

(Means for Solving the Problems) The present invention provides a method for blowing pulverized coal by installing a pulverized coal injection nozzle horizontally in a blowing branch pipe, in which the pulverized coal injection nozzle is used to inject pulverized coal and oxygen into the air. In addition, the distance between the tip of the blast furnace tuyere and the tip of the pulverized coal injection nozzle was set to 3.
This is a method of injecting pulverized coal from a blast furnace tuyere, which aims to keep the oxygen concentration in the blast at 30% or more while maintaining the pulverized coal at 150 kg/P, T or more while maintaining the oxygen concentration at 0.00 Tsuru or less.

In the present invention, the reason why pulverized coal of 150 kg/P and 7 or more is injected is to achieve the purpose of reducing the amount of coke charged from the top of the furnace to the furnace. This is to set the concentration to 30% (9% enrichment) or higher and burn the 150 kg/P, T pulverized coal. That is, according to the experiments conducted by the present inventors, the fact as shown in FIG. 3 was confirmed.

Furthermore, the reason why the distance between the tip of the blast furnace tuyere and the tip of the pulverized coal injection nozzle is kept at 300 mm or less is that, as mentioned above, in the method of the present invention, a large amount of oxygen is injected so that the oxygen concentration is 30% or more.
Correspondingly, a large amount of pulverized coal is also injected, so the front end of the pulverized coal injection nozzle becomes extremely hot, and if this high temperature area occurs inside the blast furnace tuyere or blower branch pipe, it may cause melting or damage. , combustion ash of pulverized coal adheres to the inner wall surface of the blast furnace tuyere, causing problems such as the inner diameter becoming smaller.
The high temperature part in front of the tip of the pulverized coal injection nozzle is intended to be located in the raceway inside the furnace. Therefore, if this distance exceeds 300ts, the above problem will occur.
It was set to 0n or less.

(Function) The present invention provides a method in which a pulverized coal injection nozzle is provided horizontally in a blowing branch pipe to inject pulverized coal, in which the pulverized coal injection nozzle has a double structure for blowing pulverized coal and oxygen. At the same time, the distance between the tip of the blast furnace tuyere and the tip of the pulverized coal injection nozzle is
This method reduces the unit consumption of coke charged from the top of the furnace because the oxygen concentration in the air is maintained at 30% or higher and pulverized coal is injected at 150 kg/P or higher while maintaining the temperature at or below 0.00 Tsuru. be able to.

(Example) The present invention will be explained below based on FIGS. 1 and 2.

FIG. 1 is an explanatory diagram of the method of the present invention, FIG. 2(A) is a front view of a central vertical section of the pulverized coal injection nozzle used in the present invention, and FIG. 2(B) is a side view of (A).

That is, the pulverized coal injection nozzle 1 used in the method of the present invention
1 has a pulverized coal injection part 12 and an oxygen injection part 13 formed on the outer periphery of this pulverized coal injection part 12 as the main part of the structure, and this structure and this pulverized coal injection nozzle 11 By providing it horizontally within the blast branch pipe 3, it serves to transfer the combustion of pulverized coal to the furnace core side.

Further, the pulverized coal injection nozzle 11 is provided with a cooling water passage 14 on its outermost periphery so as to be able to withstand high heat, and an optical fiber 15 is provided in the oxygen injection part 13.
It is designed so that the condition inside the raceway can be monitored by inserting it through the raceway.

In this embodiment, the front surface of the oxygen blowing part 13 is closed, and three blowing holes 16 are provided in this closed part. In addition, this blast furnace tuyere is based on injection of a large amount of pulverized coal in a highly oxygen-concentrated state;
It also makes it possible to perform so-called super-compound blowing in which flux such as limestone, steam, etc. are also blown.

Therefore, the pulverized coal injection nozzle 11 configured as described above
The method of the present invention is carried out by installing the blast furnace horizontally within the blast pipe 3 so that the tip thereof is within 3 oools from the tip of the blast furnace tuyere 1.

Results when the method of the present invention was carried out under the following conditions (■, ■
) are shown in the table below. For comparison, the results of the conventional method (
■) are also shown in the table below.

Experimental conditions Experimental furnace type: Small high-pressure melting furnace Hearth diameter: φ900 mm Height: 3.5 m Internal volume: 2.4 m Number of tuyeres = 3 Hot air temperature: 1000°C Pulverized coal type: Lithgow coal Pulverized coal particle size: - 200 mS, 80% or more * Distance between the tip of the blast furnace tuyere and the tip of the pulverized coal injection nozzle As is clear from the above table, the method of the present invention was able to reduce the coke consumption rate with stable blast furnace operation.

(Effects of the Invention) As explained above, the present invention provides a method for blowing pulverized coal by horizontally installing a pulverized coal injection nozzle in a blower branch pipe.
The pulverized coal injection nozzle is divided into two for pulverized coal and oxygen injection.
In addition to having a heavy structure, the distance between the tip of the blast furnace tuyere and the tip of the pulverized coal injection nozzle is maintained at 300 mm or less, the oxygen concentration in the blast is 30% or more, and the pulverized coal is 150 kg/
Since it is a method of injecting more than P and T, it is possible to reduce the basic unit of coke charged from the top of the furnace, and also to enable stable blast furnace operation.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the method of the present invention, Figure 2 (a) is a central vertical sectional view of the pulverized coal injection nozzle used in the present invention, (b) is a side view of (a), and Figure 3 is a pulverized coal injection nozzle. FIG. 4 is a diagram showing the relationship between charcoal and oxygen concentration and the combustion status in the blast furnace, and is an explanatory diagram of the conventional method. 1 is a blast furnace tuyere, 3 is a blower branch pipe, and 11 is a pulverized coal injection nozzle. Patent Applicant: Sumitomo Metal Industries, Ltd. Figure 1 14 1986-263906 (4) Figure 3 Dorei + 15 lights, S1 degree (Masu Figure 4

Claims (1)

[Claims] (1) In a method of blowing pulverized coal by installing a pulverized coal injection nozzle horizontally in a blowing branch pipe, the pulverized coal injection nozzle has a double structure for blowing pulverized coal and oxygen, and The distance between the tip of the mouth and the tip of the pulverized coal injection nozzle is 300.
mm or less, the oxygen concentration during blowing is 30% or more, and the pulverized coal is 150 kg/P. A method for injecting pulverized coal from a blast furnace tuyere, which is characterized by injecting at least T.