JPS6036575Y2 - Burner with tip for injecting powdered fuel into blast furnace - Google Patents

Description

[Detailed description of the invention] The present invention is a burner used for injecting powdered fuel into a blast furnace, which improves the combustibility of powdered fuel and reduces ash adhesion inside the blow pipe as much as possible. It is related to a burner that can be used.

More specifically, there is a burner with a tip that has a cooling structure, can freely adjust the shape and dimensions of the powder fuel jet nozzle, and can easily replace the jet nozzle in case of burnout, etc. It is related to.

As for the injection fuel used in blast furnace operations, due to the effects of high oil prices, heavy oil injection alone has faded, and all-coke operation has become the mainstream.

However, in order to alleviate the difficulty of all-coke operation and save on expensive coke, injection of pulverized fuel such as pulverized coal is being considered or implemented.

However, pulverized coal and other pulverized fuels (hereinafter collectively referred to as pulverized fuels) have the drawbacks of having a slower combustion rate than heavy oil and containing unresolved components such as ash.
Various measures must be taken when blowing.

This will be explained more specifically as follows.

In conventional heavy oil injection, the tip of the burner is placed near the boundary between the blast furnace siding and the blowpipe, and the injected heavy oil is almost completely burned within the tuyere and within the raceway immediately after the tuyere. If powdered fuel is injected from the same position, it will not be able to be completely combusted within the lining or raceway, resulting in a poor combustion rate.

As a result of further investigation, in order to improve the combustion rate, it was found that if the blowing position was moved upstream and the air was blown into the blowpipe, then ignited and burned within the blowpipe, almost complete combustion would occur within the raceway. Knowing this, we determined the optimal blowing position within the blowpipe and filed a separate patent application.

On the other hand, powdered fuel contains some ash to varying degrees, and this ash melts due to the heat of combustion, but when this molten material collides with the inner surface of the blowpipe, it adheres and accumulates there. Not only does it become difficult to continue the stable injection of fuel by narrowing the air passage, but there is also the danger that the injection of hot air from the siding becomes unstable.

Therefore, in the patent application mentioned above, the optimum blowing position was determined and an appropriate blowing control method was established so that ash adhesion and accumulation would not occur or progress even if the combustibility was improved. We have made efforts to prevent ash adhesion accidents by devising methods.

By the way, the inventors of the present invention have investigated various problems in powdered fuel injection from other angles, and one of them is to improve the durability of the burner.

In the case of solid-gas two-phase flow, the cooling effect of the gas is weak, so when exposing the burner to the blowpipe, it is necessary to take measures such as selecting a heat-resistant material as the burner material or adding a cooling structure. there were.

In this invention, we decided to add a cooling structure,
We came up with a burner with a multi-tube structure, but since such a burner has a cooling medium passage around the powder fuel feed passage, it would have to be a burner with a large outer diameter.
There were problems as described below.

Figure 1 is a sectional view of a burner with a triple tube structure for water cooling. It is integrated with a semicircular cap 4 in the shape of a letter, and a solid-gas two-phase flow is formed inside the inner cylinder 1 in the direction of the arrow, and between the inner cylinder 1 and the intermediate cylinder 2, and between the intermediate cylinder A cooling medium flow path as shown by the chain arrow is formed between the outer cylinder 2 and the outer cylinder 3.

When the solid-gas two-phase flow consisting of powdered fuel and carrier gas is released at the burner outlet, it is ejected as shown by 5 along with the hot air flowing around it at high speed, and undergoes ignition combustion. Since the outer diameter of the entire burner is large, the jet flow 5
It was found that a pocket portion 6 was formed between both side portions of the cap 4 and the cap 4, and this portion became a negative pressure zone and formed a vortex flow 7.

If the jet stream 5 spreads widely due to this background, the flame will come into contact with the inner surface of the blowpipe, causing a problem in which some of the ash melted by the heat of the flame will adhere and accumulate there, causing the burner to become damaged. It has been found that this has a negative effect on the meritorious advantage of improving combustibility by moving the powdered fuel jet from the blow pipe to the upstream side of the blow pipe.

The present invention was developed in light of these circumstances, and the purpose is to provide a burner that has a cooling structure such as water cooling or air cooling, and is capable of suppressing the spread of flame as much as possible. It is something to do.

The burner of the present invention, which has achieved the above objectives, consists of a burner body with a multi-tube structure and a removable tip attached to the tip of the burner body, and the central tube of the burner body forms a solid-gas two-phase flow. The outer cylinder side is used as a powder fuel feeding path, and the outer cylinder side is a cooling medium passage, and the inner diameter of the tip is not smaller than the inner diameter of the center cylinder of the burner body, and the outer diameter of the tip is in contact with the burner body. The main point is that the structure is tapered from the part to the distal end.

Next, the configuration and effects of the present invention will be explained based on the embodiment drawings. However, any modifications to the chip, cooling structure, or their mounting structure, etc., to the extent that does not contradict the spirit of the above and below are not included in this book. included in the scope of invention.

FIG. 2 is a sectional view of the tip B screwed onto the burner body A. The structure of the burner body A is generally the same as that in FIG. It is distinctive in that it is engraved with

However, the cooling structure of the burner body A and the joint structure with the tip B are not interpreted in a limited manner in this invention. For example, regarding the cooling structure, a double pipe or quadruple pipe structure, or an air cooling structure may be used. Various modifications can be made, such as providing outer fins on the outer surface of the inner cylinder 1 to the extent that they do not substantially impede the flow of the refrigerant, etc., and of course there is freedom in the selection of the material.

Furthermore, the connection structure with tip B is not limited to the screwing method as shown in the figure, but it is desirable that it be as easy to attach and detach as possible, and bayonet methods, flange methods, wedge methods, etc. can be adopted. .

As for the chip B itself, the inner diameter is the inner diameter d of the inner cylinder 1.
It is necessary that it is not substantially smaller than 1,
And the tip outer diameter D2 is the tip outer diameter of the burner body A,
It is necessary to form a tapered structure so that it becomes smaller, that is, D2<Dt.

The reason for these is that if d2<dt, the powder fed inside the burner will collide with the chip B, accelerating its wear and tear, and the condition of D2<D□ must be maintained. For example, the formation of the negative pressure zone as explained in FIG. 1 is not eliminated, and the jet stream 5 spreads, causing adhesion and accumulation of ash.

In order to satisfy these conditions, the inner surface of the tip B should be tapered with d1≦d2 (preferably d, = d2), and the outer surface should be tapered or stepped, or a combination of a taper and a step. There is a need.

The chip shown in the figure has a flat part 9 with an outer diameter one step smaller than the outside diameter of the chip body A, followed by a tapered taper 10, but it is also possible to omit the flat part and form a taper over the entire length. good.

The reason why the tip B is made detachable in this way is not only to replace the tip B itself due to wear and tear, but also to replace the burner (12 in FIG. 3) in the blow pipe (12 in FIG. 3).
1) The flammability of the powder fuel and the degree of adhesion and accumulation of ash vary depending on the tip position, the type of powder fuel, and the injection conditions of the powder fuel. This is because it needs to be replaced with the most suitable one.

For example, it has been confirmed that by increasing the protrusion length of the tapered tip B, the jet stream becomes narrower and less ash adheres, but the combustibility also decreases slightly. Do this.

FIG. 3 shows that the burner 11 of the present invention is inserted diagonally into the blow pipe 12, and powdered fuel is supplied to generate the jet flow 5.
13 is a cross-sectional view of the situation in which a blast furnace is formed.

Since the present invention is constructed as described above, the following effects can be obtained.

(1) Cooling of the burner is ensured and the frequency of replacing the burner itself is reduced, improving the safety of work in front of the furnace.

(2) Since the chip is in close contact with the water-cooling cap, sufficient durability can be achieved without using special heat-resistant metals.

(3) Since adhesion and accumulation of ash inside the blow pipe can be suppressed as much as possible, the combustibility improvement effect of powdered fuel can be enjoyed as is, and therefore, large-scale injection of powdered fuel can be operated. can be performed stably.

(4) The chip can be freely replaced with the optimal chip according to changes in the type of powdered fuel or the injection conditions.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a possible burner with a cooling structure;
The figure is a sectional view of the burner of the present invention, and FIG. 3 is a sectional view showing how it is used. 1... Inner cylinder, 2... Intermediate cylinder, 3...
...outer tube, B...chip, 12...
Blowpipe, 13...tuyere.

Claims (1)

[Scope of utility model registration request] A burner for blowing powdered fuel is arranged so as to penetrate through the wall of the blow pipe for blowing hot air connected to the blast furnace wall, and the burner is a burner having a multi-tube structure. It consists of a main body and a removable tip attached to the tip of the main body, and the center cylinder of the burner main body serves as a powder fuel supply path that forms a solid-gas two-phase flow, and the outer cylinder side serves as a cooling medium passage. The inner diameter of the tip is not smaller than the inner diameter of the center cylinder of the burner body, and the outer diameter of the tip is tapered from the contact part with the burner omelet to the tip side. Burner with tip.