JP2963422B2 - Pulverized coal burner for blast furnace operation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a pulverized coal burner used in blast furnace operation.

[0002]

2. Description of the Related Art In the operation of a large blast furnace currently in operation, a part of coke as a reducing agent is usually replaced with pulverized coal along with hot air at 1100 to 1300 ° C. and blown from a tuyere. Even when performing oxygen-enriched operations, the normal oxygen enrichment rate is only a few percent, and the pulverized coal injected is 100 kg / t.
In recent years, a technique has been proposed in which the basic unit of coke charged from the furnace top is further reduced, and more pulverized coal is injected from tuyeres instead of low-quality pulverized coal. I have. These technologies operate at an oxygen enrichment rate several times or more than the conventional ones.However, due to the large amount of pulverized coal to be injected, usually, the straight pipe section of the blower branch pipe in front of the tuyere is inclined. In the method of injecting from the direction (FIG. 5), pulverized coal burns before reaching the tuyere raceway, and obstacles such as accumulation of molten ash at the tuyere have been observed.
For example, in Japanese Patent Application Laid-Open No. 62-263906 (FIG. 6), in order to avoid these obstacles, a pulverized coal injection nozzle is provided horizontally in a blower branch pipe, and a burner has a double structure for pulverized coal and oxygen injection. It has also been proposed to specify the distance between the tuyere tip and the pulverized coal injection nozzle.

[0003]

SUMMARY OF THE INVENTION The aforementioned Japanese Patent Laid-Open Publication No. Sho 62-2
Blast furnace operation method No. etc. 63 906, as is clear from the examples, there is a much higher rate than normal oxygen Tomikaritsu, O ₂ concentration is assumed about 37%, O ₂ concentration Under the operating conditions of an oxygen blast furnace in which the temperature is set to 40% or more, the above-mentioned degree of improvement is still insufficient, and the use of a tuyere temperature adjusting gas is indispensable in order to stably and permanently continue the operation with high-concentration oxygen. There are many unresolved issues such as grasping the combustion situation at the tuyere tip is extremely important. The present invention has been made in view of such a situation, and it is possible to stably burn a large amount of pulverized coal without deteriorating the furnace condition and without shortening the life of the tuyere. It is intended to provide a device.

[0004]

Means for Solving the Problems (1) A tuyere is connected to a tip of a burner provided with a pulverized coal injection pipe, a tuyere temperature adjusting gas injection pipe, and an oxygen injection pipe, and the pulverized coal is mixed with various fluids. Blast furnace operation characterized in that the jetting angle of the nozzle is determined so that the position where the mixed fluid comes into contact with the inner surface of the tuyere is inward from the tip portion by a length equal to or less than 1/2 of the tuyere outlet diameter. For pulverized coal burners.

[0005]

The pulverized coal burner of the present invention uses cold oxygen instead of hot air as in the conventional blast furnace operation, and therefore has the following two structural features. a) The tuyere was connected to the tip of the burner where the pulverized coal blowing pipe, the tuyere temperature adjusting gas blowing pipe and the oxygen blowing pipe were installed. b) The jet angle of the nozzle such that the mixed fluid of the pulverized coal and the various fluids comes into contact with the inner surface of the tuyere from the tip end by a length of 1/2 or less of the tuyere exit diameter. Decided.

A) The nozzle having a tuyere at the tip is composed of a pulverized coal blowing pipe, a tuyere-tip temperature adjusting gas blowing pipe and an oxygen blowing pipe, and is controlled by the adjusting gas from the tuyere-tip temperature adjusting gas blowing pipe. It is intended to suppress the expansion of combustion of the pulverized coal injected to prevent the tuyere from being damaged, and to improve the mixing of oxygen and pulverized coal for efficient pulverized coal combustion. The tuyere temperature control gas above the water vapor, a blast furnace gas, coke oven gas, or N ₂ gas, CO ₂ gas, accompanied gas inert gas or decomposition endothermic reaction of equal,
There is no particular limitation as long as there is no adverse effect on the reduction of iron ore.

As for b), since a considerably large amount of pulverized coal is burned in an atmosphere having a high oxygen concentration as compared with a tuyere of a normal oxygen-enriched operation, it is necessary to strictly examine the obstacle to the tuyere. is there. As an obstacle, there is a problem that the mixed fluid containing unburned pulverized coal collides with the inner surface of the tuyere and wears the inner surface, or a problem that occurs due to accumulation of burned and molten Ash on the inner surface or the tip of the tuyere. Therefore, the position where the outer edge of the mixed fluid of the pulverized coal and the various fluids described above comes into contact with the tuyere projecting and connected to the tip of the burner provided with the pulverized coal blowing pipe, the tuyere tip temperature adjusting gas blowing pipe, and the oxygen blowing pipe. The above-mentioned trouble is effectively prevented at a specific position from the tuyere tip.

[0008] In addition, the above-described method effectively mixes the pulverized coal with the temperature control gas and oxygen, thereby appropriately burning a large amount of the pulverized coal. The burner body and the sliding tube must be kept in airtight contact with each other so that the burner body and the mechanism for preventing gas leakage and fixing the small tuyere to the furnace body are separated so that the stress applied to the small tuyere does not reach the burner body. However, it is preferable to be able to slide, and since high-concentration oxygen at room temperature is used, it is not always necessary to provide a cooling water pipe outside the pulverized coal burner, and use a corrosion-resistant steel pipe such as SUS outside the slide. be able to. Further, the surface of the sliding seat 17 formed at the end of the pulverized coal burner or at the end of the sliding pipe which is in air-tight contact with the rear end of the small tuyere is formed as a spherical or conical curved surface and can follow the movement of the small tuyere. It is preferable to do so.

[0009]

FIG. 1 shows a vertical section of a base side of a pulverized coal burner for blast furnace operation according to the present invention. An in-furnace monitoring tube 1 is arranged at the center, and extends from the base to the tip of the burner. Cleaning air for blowing off pulverized coal and the like blown into the pipe from the air inlet 2 is intermittently introduced into the inside of the furnace monitoring pipe 1. The furnace monitoring pipe 1 is communicated with a viewing window 4 through a gate valve 3.
From here, information can be obtained from inside the furnace with the naked eye or with a measuring instrument. A pulverized coal blowing pipe 5 is provided concentrically outside the monitoring pipe 1 as described above, and pulverized coal is fed into the blowing pipe 5 from a pulverized coal supply port 6. Similarly, a tuyere temperature adjusting gas injection pipe 7
And a gas (steam in this embodiment) is supplied from the tuyere temperature adjusting gas supply port 8. An oxygen pipe 9 is provided outside the tuyere tip temperature adjusting gas blowing pipe 7 and oxygen is supplied from an oxygen supply port 10. The outermost burner is a cooling water pipe 11 and a cooling water supply port 1 is provided.
2. A cooling water outlet 13 is provided.

FIG. 2 shows a longitudinal section of the tip of the pulverized coal burner shown in FIG. 1. The furnace monitoring pipe 1, the pulverized coal injection pipe 5, the tuyere temperature adjusting gas injection pipe 7, the oxygen injection pipe. 9 are shown concentrically. In this embodiment, outside the pulverized coal blowing nozzle 14 having a discharge port parallel to the axis of the burner, a tuyere temperature adjusting gas blowing nozzle 15 having a tip opening inclined inward with respect to the axial direction of the burner, oxygen, An outlet nozzle 16 is provided to prevent the mixed fluid exiting the burner from affecting the tuyere 18. Tuyere 18 at the outer periphery of the tip of the burner
A sliding seat 17 is formed for hermetically contacting the rear end.

FIG. 3 shows a sliding pipe 19 made of heat-resistant steel slidably provided instead of using the above-mentioned water-cooled jacket. A sliding seat 17 is similarly formed at the tip end. .

FIG. 4 shows an example in which the tip opening of the pulverized coal blowing nozzle 14 is provided to be inclined outside the axis of the burner, unlike the case of the previous figure, and is a mixed fluid of pulverized coal and various fluids. The position where the outermost edge is in contact with the inner surface of the tuyere 18 is shown, and the portion entering the inside from the tip portion by a length H which is １ ／ or less of the tuyere outlet diameter D becomes the outermost edge of the mixed fluid. The ejection angle of the nozzle 14 is determined at
And the fluid from 16.

[0013]

As described in detail above, when the pulverized coal burner of the present invention is used in an oxygen blast furnace, the furnace condition is impaired when operating with pure oxygen or high-concentration oxygen as the air blow. A large amount of pulverized coal can be burned safely and with little effect on the small tuyere, and a pulverized coal injection pipe is effectively combined with a pulverized coal injection pipe, a tuyere temperature adjusting gas injection pipe, and an oxygen injection pipe. It has characteristics such as preventing the tuyere from being damaged by preventing the pulverized coal injected from the tank from expanding and improving mixing with the pulverized coal for efficient pulverized coal combustion. Can be expected to be high.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a base side of a pulverized coal burner for blast furnace operation of the present invention.

FIG. 2 is a longitudinal sectional view of a tip portion of the burner.

FIG. 3 is a view of another embodiment (longitudinal section at the tip) of the present invention using a sliding pipe instead of a cooling water pipe.

FIG. 4 is an explanatory diagram showing a contact point of a mixed fluid with a small tuyere in the present invention.

FIG. 5 is a view of a conventional ventilation branch pipe.

FIG. 6 is a view showing a conventional example of a ventilation branch pipe at the time of high oxygen enrichment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace monitoring pipe 2 Air inlet 3 Gate valve 4 Viewing window 5 Pulverized coal injection pipe 6 Pulverized coal supply port 7 Tuyere tip temperature adjustment gas injection pipe 8 Tuyere tip temperature adjustment gas supply port 9 Oxygen injection pipe 10 Oxygen supply port 11 Cooling Water pipe 12 Cooling water supply port 13 Cooling water discharge port 14 Pulverized coal blowing nozzle 15 Tuyere temperature adjusting gas blowing nozzle 16 Oxygen blowing nozzle 17 Sliding seat 18 Tuyere 19 Sliding pipe

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masahiro Matsuura 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Masayuki Watanabe 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Incorporated (72) Inventor Saburo Sakurai 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Hiroyuki Nakamura 2-18-37, Minami-Doshibori, Yokohama-shi, Kanagawa (72) Inventor Masao Kawamoto 5-10-1-206 Isogo, Isogo-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Seigo Genban 47-67, Nakao-cho, Asahi-ku, Yokohama-shi, Kanagawa Prefecture (72) Naototake Yamada 748- Isshiki, Hayamacho, Miura-gun, Kanagawa 6 (56) References JP-A-63-171818 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C21B 7/00 309 F23D 1/00 F23L 7/00

Claims (1)

(57) [Claims] 1. A tuyere is connected to a tip of a burner provided with a pulverized coal injection pipe, a tuyere tip temperature adjusting gas injection pipe and an oxygen injection pipe, and a mixed fluid of the pulverized coal and various fluids is supplied to an inner surface of the tuyere. The pulverized coal burner for blast furnace operation , characterized in that the jetting angle of the nozzle is determined such that the position in contact with the inside of the tuyere outlet is not more than 1/2 of the tuyere outlet diameter.