JPH049414A - Method for blowing pulverized coal to blast furnace - Google Patents

Abstract

PURPOSE:To attain a sufficient mixing state of hot wind and pulverized coal even with one piece of pulverized coal blowing lance and to exceedingly improve the combustion rate of the pulverized coal by forming the projections to be provided on the inside surface of a tuyere or blow pipes to a spiral or V shape. CONSTITUTION:The projections 6 having the spiral or V shape or further the combined shapes thereof are provided on the inside surface of the tuyere 1 and/or the blow pipe and the pulverized coal blowing lance 3 is so disposed that a mixed phase flow 4 composed of the pulverized coal and the carrier gas thereof comes into contact with the projections 6. The flow along the projections 6 is, therefore, formed, in addition to the axial flow of the hot wind 8, in the tuyere or the blow pipe. The mixed phase flow 4 is mainly intruded into the flow of the hot wind 8 along the projections 6 and while a part thereof is released as shown in Fig., the mixed phase flow moves along the projections 6. Consequently, the pulverized coal is dispersed into the outer peripheral part where the quantity of the hot wind flowing in the tuyere or the blow pipe is large. The combustion rate is thus exceedingly improved.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a technology for injecting pulverized coal into a blast furnace, and in particular, by improving the combustibility at the tip of the tuyere, it is possible to inject a large amount of pulverized coal, The present invention relates to a method of injecting pulverized coal into a blast furnace that can significantly reduce the coke ratio or the cost of producing pig iron.

<Prior Art> In order to make it possible to inject a large amount of pulverized coal into a blast furnace, it is essential to increase the combustion rate of the pulverized coal at the blowpipe, tuyere, or tuyere tip (raceway). If the combustion rate decreases, various problems will occur, such as ventilation obstruction due to the accumulation of unburned pulverized coal in the blast furnace, or a decrease in the W conversion rate between coke and pulverized coal due to oblique discharge as dust.

In order to avoid such problems, the following measures have been taken to improve the combustibility of pulverized coal.

■ High volatile content (selecting a type of coal with good ignitability, ■ Decreasing the particle size of pulverized coal, ■ Increasing the oxygen enrichment rate of the blast air, ■ Increasing the blast temperature.

Furthermore, in Japanese Patent Application Laid-Open No. 61-124510, a protrusion is provided on the inner surface of the tuyere or blowpipe, and a fuel injection nozzle is placed at the tip of the tuyere to inject fuel and mix the fuel and hot air. A method of promoting is disclosed.

A schematic diagram of general pulverized coal injection is shown in Figure 4 for reference.

<Problems to be Solved by the Invention> Among the prior art techniques shown above, (1) to (2) are measures taken during normal operation, and have certain effects.

However, to further improve combustibility, pulverized coal and hot air (
It is necessary to harden the mixing with oxygen), and in this sense, the method of JP-A-61-124510 is effective, but the local gas flow that is formed behind the protrusion is The purpose is to promote mixing of pulverized coal and hot air by utilizing the turbulence of the tuyere or blowpipe. ) is considered necessary, and is also expressed as such in the drawings of the official gazette.

The present invention has been made in order to solve the above-mentioned problems and to provide a technology in which a sufficient mixing state of hot air and pulverized coal can be obtained in the tuyere and/or blowpipe even with a single pulverized coal injection lance. It is.

<Means for Solving the Problems> In order to improve the combustion rate of pulverized coal, it is necessary to promote contact mixing between oxygen blown in as hot air and pulverized coal blown in from a lance.

If it were possible to disperse the pulverized coal injected from a single pulverized coal injection lance into the outer periphery, which accounts for the majority of the hot air flowing through the tuyere and/or blowpipe, it would be possible to dramatically increase the We thought that the combustion rate could be increased, and as a result of studying a method for injecting pulverized coal to achieve this, we came up with the present invention.

The present invention provides a spiral or inverted V-shaped protrusion on the inner surface of the tuyere and/or blowpipe, and a multiphase flow of pulverized coal and its carrier gas is blown into the protrusion from a pulverized coal injection lance. To the blast furnace characterized by making it hit? This is the Il'PA charcoal injection method.

<Function> According to the present invention, the tuyere 1 and/or the blow pipe 2
As shown in FIGS. 1 and 2, a protrusion 6 in the shape of a spiral, an inverted V-shape, or a combination thereof is provided on the inner surface of the pulverized coal injection lance 3. The pulverized coal injection lance 3 is arranged so as to be hit by the multiphase flow 4 of coal and its carrier gas.

Therefore, in addition to the axial flow of the hot air 8, a flow along the protrusions is formed within the tuyere or blowpipe. The multiphase flow of pulverized coal and its carrier gas injected from the pulverized coal injection lance is mainly caught in the flow of hot air along the protrusions, and some of it is released as shown in Figures 1 and 2. The pulverized coal moves along the protrusions on the inner surface of the tuyere and/or the blowpipe, and as a result, it becomes possible to disperse the pulverized coal in the outer circumference of the hot air flowing through the tuyere or blowpipe, where the amount is larger. This makes it possible to dramatically improve the combustion rate.

Even if the pulverized coal injection lance is set upstream of the protrusion and at the center of the cross section of the tuyere or blowpipe, the multiphase flow of the injected pulverized coal and its carrier gas will occur as shown in Figure 4. As it spreads further downstream, some of it collides with protrusions and flows along them. Further, if the installation section of the protrusion is long, even if the tip of the pulverized coal injection lance is placed within that section, the effect can be expected to some extent for the same reason.

In addition, the shape of the protrusion is not limited to a spiral shape, an inverted F-shape, or a combination thereof. Any shape that can be used will suffice.

<Example> In order to confirm the effects of the present invention, an experiment was conducted in a pulverized coal tP8 furnace that simulates the tuyere of a blast furnace.

The furnace shape and air blowing conditions are as follows.

Tuyere diameter: 56wφ, Furnace inner diameter: 600mφ, Furnace length: 4
000 deception, air flow rate: 3Nd/m, 0□:23-%, air temperature: 1100℃, pulverized coal: TC73wt%, VM32
wt%, pulverized coal injection amount: 0.4kg/sm (actual 1!
(equivalent to 150kg/tpig), air amount for conveying pulverized coal: 5ONZ/+m.

The distance between the tip of the pulverized coal injection lance and the tip of the tuyere is 200-
The second case is fixed at
Pulverized coal combustion experiments were conducted with and without protrusions of the type shown in the figure.

Figure 3 shows a developed view and a cross-sectional view of a tuyere with protrusions9.
As shown in the diagram, the protrusions are located 45 meters downstream from the tip of the pulverized coal injection lance 3, and the protrusions extend 45 meters to the left and right.
A projection with a height of 10 mm and a thickness of 20 mm is provided at an angle of 5 degrees over the entire circumferential angle of 320 degrees (160 degrees on one side).

Table 1 shows the experimental conditions and pulverized coal combustion rate.
The unburned char was sampled by a sampler at the tuyere axis position, and its chemical composition was determined by the following formula.

(SiO2%”+A/, O,%0) Here, α: Combustion rate (%), C,, SiO2%, JV z O* %: C of pulverized coal
, Sto! , Nt (h content (wt%), C'',
Si Island %", NtOx %": C, Sin! of sampled unburned char! .

A1. O, content (11E%) Note that the distance of 700 m5 from the tip of the tuyere roughly corresponds to the raceway depth in an actual blast furnace, and if a combustion rate of at least 80% or more can be obtained at this position, In a blast furnace, pulverized coal injection operation can be carried out without any problems, and it has been empirically known that if the ratio is less than 70%, there will be adverse effects such as ventilation obstruction.

As shown in the experimental results in Table 1, when a spiral protrusion is provided in the tuyere and the pulverized coal injection lance is set so that the multiphase flow of pulverized coal and its carrier gas hits this protrusion, a dramatic increase in The combustion rate has been improved. In addition, if there is a protrusion, the effect of improving the combustion rate can be obtained even when the pulverized coal injection lance is set in the center of the tuyere (Experiment No. 2). The effect is smaller than when set (Experimental floor 4).

<Effects of the Invention> According to the method of the present invention, the combustion rate of pulverized coal in the blast furnace raceway can be dramatically increased, thereby achieving a pulverized coal injection rate of 150 kg/[-ρig or more, which could not be achieved with the conventional technology. was completed.

[Brief explanation of the drawing]

FIGS. 1 and 2 show protrusions and W! according to the present invention. An explanatory diagram of the flow of a multiphase flow of powdered coal and its carrier gas, (a) is a cross-sectional view of the tuyere, (b) is a developed view of (a), (C) is a side cross-sectional view of (a), and Fig. 3 are explanatory diagrams of the protrusions used in the examples, where (a) is a cross-sectional view of the tuyere, (b) is a developed view of (a), and the fourth
The figure is a schematic diagram showing the state of pulverized coal injection into a blast furnace. ...Wings, 2...Flow pipe,...
...Pulverized coal injection lance, ...Multiphase flow of pulverized coal and its carrier gas, ...Raceway, 6.Protrusions, ...Furnace inner wall surface,
8...Hot wind. Patent applicant: Kawasaki Steel Corporation

Claims (1)

[Claims] A spiral or inverted V-shaped protrusion is provided on the inner surface of the tuyere and/or blowpipe, so that the multiphase flow of pulverized coal and its carrier gas blown from the pulverized coal injection lance is blown onto the protrusion. A method for injecting pulverized coal into a blast furnace, which is characterized by: