Method and device for blast furnace to blow coal powder

Abstract

The invention puts forward a method and device for a blast furnace to blow coal powder. Characterized by employment of several short spray guns, a large incidence angle, accurate positioning of spray guns, small heat radiation and long life of blowpipes, and adoption of ceramic nozzles, the new method and new device of the invention aims to eliminate various defects in prior art, such as small coal powder incidence angle, restriction by high speed hot airflow, inadequate mixing with hot air, long length and long service life of spray guns, large heat radiation and short service life of blowpipes, and hard use of oxygen-coal lances, etc. According to the invention, on the blowpipes of each air ports, each short spray gun is inserted into each installation seat, and coal powder blown into a blast furnace enters from blowing inlets positioned on a lateral side of each installation seat, then reaches the inside of each short spray gun through coal spraying holes that are disposed on tube walls of the short spray guns and are over against the blowing inlets, and is finally blown into the furnace through each short spray gun. The device of the invention at least comprises: a blowpipe with a coal powder precombustion function, short spray guns, installation seats, ball valves, locking devices, coal conveying branch pipes, a distributor, a small ball valve, a coal conveying pipe, and an inlet connecting piece.

Description

technical field [0001] The invention belongs to the technical field of ironmaking, and relates to blast furnace coal injection technology, in particular to a method and device for blast furnace pulverized coal injection. Background technique [0002] As we all know, the existing method of blast furnace pulverized coal injection is: on the straight blowing pipe of each tuyere, one or two spray guns are obliquely inserted into the straight blowing pipe at an angle of 10-13° between the center line and the straight blowing pipe center line. The blowpipe, the end of the spray gun exposed outside the pipe is used as the coal injection inlet, and the coal powder is directly injected into the straight blowpipe through this inlet, and then enters the blast furnace through the tuyeres together with the hot air. This method of injecting pulverized coal has caused the following problems: [0003] (1) The incident angle of pulverized coal is small, and it is restricted by the high-spee...

AI Technical Summary

Problems solved by technology

[0003] (1) The incident angle of pulverized coal is small, constrained by the high-speed hot air flow, and the mixing with the hot air is not sufficient

The angle between the existing pulverized coal spray gun and the direct blow pipe is very small. Usually, in order to prevent the tuyere from being worn out, the head of the spray gun is slightly bent at a certain angle to align with the center, so that the actual incident angle of coal injection is kept parallel to the center line of the direct blow pipe. At the same time, the initial velocity of pulverized coal sprayed from the spray gun is mostly 18-30m / s, while the velocity of hot air is higher than 200m / s. It is difficult for the pulverized coal to diffuse through the hot air stream, and the mixing of the pulverized coal and the hot air is not sufficient, which is one of the main reasons for the low combustion rate of the pulverized coal injection in the current blast furnace

[0004] (2) The spray gun is long and the service life is short

As we all know, the spray gun is a stainless steel pipe with a length of more than 2m, and its lifespan is less than 3 months in hot air at a temperature of 1150-1300°C.

Especially in the case of high oxygen enrichment, the service life is even less than 10 days, requiring frequent replacement and high cost of use

[0005] (3) The position of the gun head cannot be fixed, causing the tuyere to wear

When encountering repeated use or poorly made spray guns, it is difficult to insert the gun head into the best position

At the same time, in the normal production process, due to the long-term high temperature and oxidation of the gun head, there will be damage such as natural bending, so even if the gun head is inserted in the best position, it will deviate during the production process.

It can be seen that the existing method of injecting coal powder makes the position of the gun head unable to be accurately positioned, and has instability, which is the direct cause of the wear of the tuyeres

Relying on artificial inspection and adjustment can only alleviate the occurrence of tuyere wear, but it is impossible to fundamentally eliminate the tuyere wear

[0006] (4) Straight blowing pipe has large heat dissipation and short service life

Under the existing pulverized coal method, inserting the gun at a small angle causes the intersecting line between the gun hole and the refractory material of the straight blow pipe to be very long; while the position of inserting the gun is at the outlet of the straight blow pipe, where the refractory material is the weakest, and it is necessary to increase the Large opening diameter, these factors have seriously damaged the integrity of the straight blow pipe lining refractory material

In order to overcome the weak refractory material, it is necessary to increase the protective sleeve, which increases the size of the shell, increases the surface area, and increases the heat loss

Therefore, under the existing coal injection method, the direct blowing pipe not only has a large heat dissipation, but also has a short life

[0007] (5) It is difficult to use the oxygen coal gun, which hinders the progress of coal injection technology

But unfortunately, the existing method of injecting pulverized coal has brought fatal life problems to the oxygen-coal gun, making this simple technology unable to obtain the reliability of production practice so far, and all kinds of beneficial attempts cannot be produced. accepted by

The reason is: under the conditions of the existing gun insertion operation, the oxygen-coal gun can only be made of metal materials, and in the local high-oxidizing high-temperature environment formed by it, the oxidation speed of the oxygen-coal gun is significantly accelerated, and the service life Greatly shortened; although various protective measures to slow down the oxidation rate were applied, the oxygen coal gun failed because it could not be made of non-metallic ceramic materials and could not meet the requirements of the highly oxidizing high-temperature environment produced by itself.

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