JPH0674448B2 - Blast furnace powder raw material injection lance - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a structure of a lance used for blowing a powder raw material and / or a fuel into a blast furnace.

[Conventional technology]

As the raw material in the blast furnace operation, in order to secure the air permeability in the furnace and obtain a smooth unloading of the raw material, ore and coke with a certain particle size or more are used, and use of powdered ore and coke is avoided. Therefore, powdered ore and powdered coke have not been conventionally used as raw materials in blast furnace operation, but recently, the powdered raw material is blown from the tuyere to adjust the components of the hot metal and slag in the furnace and the powder raw material. Blast furnace operation began to be carried out for the purpose of effective use. However, blowing the powder raw material from the tuyere causes abrasion on the inner surface of the blow pipe tuyere compared to the conventional heavy oil blowing, which in turn causes a serious accident due to damage to the blow pipe and tuyere. Therefore, it is necessary to take various measures when injecting powder.

As shown in FIG. 2, Japanese Patent Application Laid-Open No. 60-402 has a multi-cylinder structure, and a central cylinder forms a powder feeding passage 1 forming a solid-gas two-phase flow.
The intermediate cylinder 2 and the outer cylinder 3 serve as cooling medium passages, and the powder injection lance tip 4 has a tapered tapered outer shape that satisfies the following conditional expression. It's Lance.

θ ≦ 1400L ₁ ² −1290L ₁ +295 0.1 <L ₁ ≦ 0.35 0 <θ <180 where θ: taper angle of lance tip (°) L ₁ : distance from tuyere and blow pipe boundary to lance tip (M).

This blow lance has the following problems.

Since the cooling medium passage for preventing lance melting damage is installed side by side, the lance has a large outer diameter and the air passage is narrowed.

Since the cooling medium for preventing lance melting damage is used, the blast temperature is lowered.

At the tip of the lance, the formation of a vortex flow is suppressed by mounting the taper cap, but since the outside diameter D ₁ of the part other than the tip inserted into the blow pipe is large, a large vortex flow is generated at the rear part of the lance. You can Therefore, the powder blown particles and the ash content collide with the blow pipe and the inner wall of the tuyere due to the turbulent flow due to the vortex flow, and adhere to the blow pipe and the inner wall of the tuyere. Due to this phenomenon, the inner wall of the tuyere is abraded by the abrasive powder.

[Problems to be solved by the invention]

In a heavy oil blowing burner which is arranged so as to penetrate through the wall of a blow pipe for blowing hot air connected to a conventional blast furnace tuyere, the powder blowing raw material is the blow pipe and the tuyere inner wall. Collides with and causes wear.

On the other hand, when the burner is projected near the tip of the tuyere so that the blown raw material does not collide with the blow pipe and the inner surface of the tuyere, the radiant heat from the raceway softens or melts the burner tip.

Therefore, it is necessary to select a lance arrangement that does not cause the blown powder to collide with the inner wall of the tuyere and that does not cause the lance tip to soften or melt due to radiant heat.

The present invention relates to a lance used for blowing powder from the tuyere of a blast furnace, does not hinder the blowing of air from the tuyere, continues the stable blowing of the powder, and powders the inner wall of the tuyere. The purpose is to provide a properly shaped lance so as not to collide with the lance.

[Means for solving problems]

The lance of the present invention has an insertion angle of 10 with respect to the tuyere axis.
° to 60 °. The opening surface at the tip of the lance is in the range of 0 ° ± 30 ° with respect to the tuyere axis, and the center of the lance opening is on the tuyere axis and the distance l from the tuyere tip is The condition defined by the following formula shall be satisfied.

Where, Wf: powder injection rate (kg / sec) Ustr: blast air velocity (m / s) Wa: mass flow rate of air (kg / m ² · sec) De: eddy diffusion coefficient (m ² / sec) l: Distance from tip of tuyere to center of lance opening (m) D: Tuyere diameter (m) [Operation] The lance of the present invention has the following features.

(1) A lance structure that continues stable blowing of powder and prevents the powder from colliding with the tuyere inner wall.

(2) The lance is not softened by the radiant heat from inside the raceway.

FIG. 1 is a layout drawing of a powder raw material blowing lance 4 which is adapted to penetrate into a hot air blowing blow pipe 7 connected to a blast furnace tuyere 6 through a wall 7 of the blow pipe. In FIG. 1, the hot air 10 has a temperature of 900 to 1200 ° C., a pressure of 3 to 5 kg / cm ² G, and a velocity of 200 to 250 m / s.
The tuyere 6 has a structure in which the inside is water-cooled in order to allow hot air 10 to flow and to be exposed to high heat by being projected into the blast furnace. Further, the tuyere 6 is normally installed downward at an angle θt with respect to the central axis of the blow pipe 7. And the material is Cu. The inner wall surface of the blowing lance 4 is coated with ceramics or a metal having heat resistance and abrasion resistance, since abrasion powder 11 such as dust collection dust and iron ore powder passes therethrough. Alternatively, the blowing lance 4 itself may be made of ceramic or a material having heat resistance and abrasion resistance. The abradable powder raw material passing through the blow-in lance is jetted from the tip of the lance and is carried in the tuyere 6 direction by the hot air 10 flowing in the blow pipe. The abrasive powder material 11 is carried in the tuyere direction, and the lance tip is made into a groove to prevent it from colliding with the inner wall of the tuyere, and the surface of this groove faces the air flow direction and is parallel to the air flow. Position the lance so that the angle is close to.

Further, when the lance 4 is projected to the tip of the tuyere, the lance bends and melts due to radiant heat from the raceway.

Therefore, the shape and arrangement of the lance are determined as follows in order to prevent the abrasive powder from colliding with the inner wall of the tuyere and to prevent the softening of the lance.

First, regarding the lance shape, when abrasive powder is ejected from the tip of the blowing lance, it is carried toward the tuyere tip by the hot air 10 flowing in the blow pipe 7 and is swirled to the third position.
It gradually expands as shown in the figure.

This phenomenon occurs in JTDavies: Turbulence Phenomena, (197
2) Of [Academic Press] P.86 to P.89, P.88 (2.1
As clearly stated as a general formula in Eq. (8), a fluid 1 flows into a pipe 1 in a turbulent state and a fluid 2 flows into the pipe.
Is equivalent to the case where air is continuously blown at a constant flow rate, and the fluid 2
Can be understood as a behavior of riding on the flow of the fluid 1 and flowing down while mixing / diffusing with the fluid 1 by the turbulent vortex of the fluid 1.

And this mixing / diffusion process, eddy diffusion coefficient, fluid 1
And the blowing speed of the fluid 2.

The inventors of the present invention described the fluid 2 in the equation (2.18) 2
It was confirmed that the present invention can be applied even in the case of a jet of fine powder as in the present invention.

That is, the diffusion of the powder at this time is given by the equation (1).

φ = {Wf ・ Ustr / 4πWa ・ De ・ s} × exp {−Ustr (s−1) / 2De} …… (1) De ＝ 0.015μ (Re) ^0.875 / ρ Re ＝ ρD ・ Ustr / μ where φ: powder amount / air amount ratio [-] Wf: powder blowing amount (kg / sec) Ustr: blast air velocity (m / sec) Wa: mass flow rate of air per unit area (kg / m ² sec) ) De: Eddy diffusion coefficient (m ² / sec) l: Distance from tuyere tip to center of lance opening (m) s: Bus length (m) μ: Air viscosity (kg / msec) ρ: Air density (kg / m ³ ) Re: Reynolds number (−) Diffusion of powder ejected from the tip of the lance depends on the shape of the lance. Fig. 4 shows a 1380 m ³ blast furnace 1/2 model device, and the angle θ between the tuyere center axis and the lance insertion is kept constant at 30 ° and the lance shape and powder particle diffusion at 100 mm from the injection point are shown. Show the relationship.

From FIG. 4, the diffusion coefficient Dp of the blown particles is lowest when the aperture surface at the tip of the lance is the same as the central axis of the tuyere. Therefore, it is best for the shape of the lance to match the angle at which it enters the blow pipe and to face the opening surface of the lance, facing the air blowing direction, and to be the same as or parallel to the tuyere central axis so that blown particles do not diffuse. Is the way.

Next, the position of the lance tip from the tuyere tip becomes a problem. When the tip of the lance is projected to the tip of the tuyere, the blown powder with abrasion does not collide with the inner wall of the tuyere, but the lance may be melted and damaged by the radiant heat in the raceway. From this point, it is necessary to separate from the tuyere tip as much as possible. However, on the other hand, if the powder particles ejected from the tip of the lance are separated from the tip of the tuyere, the powder particles may collide with the inner wall of the tuyere and cause abrasion of the inner wall of the tuyere. The equation (1) is expanded to determine the limit range, and the following equation (2) is given.

4πWa ・ De ・ s ・ φ / Wf ・ Ustr = exp {-Ustr (s-1) ・ 2De} (2) Here, the lance position is located at the tuyere center axis when the distance is 1 from the blowing point. In this case, it is sufficient that the powder particles do not collide with the inner wall at the tip of the tuyere at a position D / 2 away from the axis.

In this case, s = {l ² + (D / 2) ² } ^1/2 where D: tuyere inner diameter (m), and equation (2) can be rewritten as equation (3).

4πWa ・ De ・ {l ² + (D / 2) ² } ^1/2・ φ / Wf ・ Ustr = exp {-Ustr ({l ² + (D / 2) ² } ^1/2 -l) / 2De} (3) Here, the smaller the powder amount / air amount ratio φ, the less the abrasion of the tuyere inner wall. In the 1/2 model experiment, powder injection was performed and the wear limit position of the tuyere inner wall was measured. By substituting this measurement result into the equation (3), φ = 0.0001 was obtained.

Therefore, the wear of the tuyere inner wall can be prevented by setting the position l from the tip of the tuyere to the tip of the lance where φ = 0.0001 or less under various actual operating conditions with the set equipment. This position l is calculated from equation (3), Is obtained as l satisfying the condition of.

As a numerical solution of the upper limit of l, y ₁ = 4πWa · De · {l ² + (D / 2) ² } ^1/2 · φ / Wf · Ustr …… (4) y ₂ = exp {− Ustr {(l ² + (D / 2) ² ) ^1/2 −l} / 2De (5) Here, y ₁ = y ₂ , so l is substituted into equations (4) and (5). , Y ₁ , y ₂ is the upper limit position 1 from the tuyere tip to the lance tip.

Next, consider the softening position l'of the lance. The tip of the lance is heated in the raceway by radiative heat transfer generated during coke combustion.

The radiant heat transfer Q ₁ from the raceway to the lance is Q ₁ = (α / 2π) ・ A (Tc ⁴ −Tr ⁴ ) …… (6) Also, the radiant heat transfer Q ₂ from the lance to the ambient temperature is Q ₂ = (Α / 2π) ・ A (Tr ⁴ −To ⁴ ) …… (7) where α: Solid angle [degree] A: Area receiving radiant heat [m ³ ] Tc: Raceway temperature [° K] Tr : Lance softening and melting temperature [° K] To: Atmospheric temperature [° K].

The solid angle α is expressed by equation (8).

α = {(1-cosβ) / 2} × 4π (8) where β is the incident angle of the radiant heat, and equation (8) is expanded to equation (9).

cos β = (1− (α / 2π)) (9) Therefore, l ′ at the tuyere radius D / 2 is obtained as in the following equation (10).

tan β = D / 2l ′ (10) From the above, if the material of the lance to be used is determined and the softening and melting temperatures thereof are determined, the limit position l ′ for bending and melting loss of the lance can be calculated.

The lance softening limit position 1'and the tuyere wear limit position 1 were calculated for the actual blast furnace by substituting the conditions in Table 1 using the above formula.

Table 1 (Operating conditions) Furnace volume V 1380m ³ Blade diameter D 0.12m Air temperature BT 1000 ℃ Air pressure BP 3000g / cm ² Airflow velocity U 200m / s Powder injection rate WS 100g / Nm ³ −air Powder transportation Gas velocity Uw 20m / s Lance softening temperature Tr 1100 ℃ Raceway temperature Tc 2000 ℃ Atmospheric temperature To 30 ℃ Regarding tuyere inner wall wear, from equations (4) and (5), l = 580m
Calculated as m. Also, the softening limit position l'of the sensor is 63 mm.
Is calculated. The lance groove hole surface angle is 0 °.
The above equation is expressed by the following equation in relation to the tuyere diameter.

0.53 ≦ l / D <4.83 where, l: Lance tip position from tuyere tip (mm) D: Tuyere diameter (mm).

However, the softening limit position 1'may vary greatly depending on the lance material, and it is possible to select a material that does not substantially soften to the tuyere.

〔Example〕

Under the operating conditions of the blast furnace shown in Table 1, the angle θB to insert through the wall into the hot-air blowing blow pipe connected to the blast furnace tuyere, the angle θd to the tuyere central axis of the opening surface of the lance
(See FIG. 1), and the lance position from the tip of the tuyere were changed variously, and the shape and position of the lance for blowing the powder raw material from the tuyere were examined.

Here, the angle θR of the groove surface of the lance has the following relationship.

θR = θB−θt where θt is the installation angle (°) of the tuyere to the blow pipe.

Examples are shown in Tables 2 and 3.

In Table 2, when the position of the lance is 400 mm from the tip of the tuyere, the arrangement of the lance in which the blown powder did not collide with the inner wall of the tuyere is indicated by a circle.

From Table 2, it is possible to determine a suitable condition in which the tuyere inner wall is not worn. Table 3 shows that the insertion angle into the blow pipe is 30 ° and the angle between the groove surface of the lance and the tuyere center axis is 0 °.
And 30 ° (the groove hole surface is parallel to the tuyere center axis), the relationship between the lance position from the tuyere tip and the collision position of the blown powder to the tuyere inner wall was carried out and shown. It was

From Table 3, when the groove surface angle is 0 °, 50mm from the tuyere tip
As described above, it was confirmed that the tip of the lance was bent due to heat, and that the tip of the tuyere was worn by the powder-blown raw material.

Also, at the 600 mm position, the distance from the tip of the tuyere was long, so the spread due to the diffusion of blown particles increased, and wear on the tuyere inner wall was confirmed.

When the groove surface angle is + 30 °, the lance limit position at which the inner wall is worn becomes shorter than when the lance limit position is 0 °.

〔The invention's effect〕

In a 1380 m ³ blast furnace, the lance insertion angle into the blow pipe was 30 °, the cutting angle of the lance groove hole surface was 30 °, and the lance position was 200 mm from the tuyere tip. Powder injection from the mouth was performed.

The shape and arrangement of the lance according to the present invention does not hinder the blowing of air from the tuyere, does not cause wear and softening of the lance, does not melt, and causes no tuyere damage due to blown powder. It was possible to continue the stable blowing of.

As a result, it was possible to obtain a great effect on the stable operation of the blast furnace.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the arrangement of lances according to an embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view of a conventional lance (a) blow pipe.
(B) A longitudinal sectional view of the tip of the lance, FIG. 3 is a schematic view showing the spread of blown particles ejected from the tip of the lance, and FIG. 4 shows the relationship between the shape and arrangement of the lance and the diffusion coefficient of the blown particles. It is a graph. 1 ... Inner cylinder, 2 ... Middle cylinder, 3 ... Outer cylinder, 4 ... Lance, 5 ... Taper cap, 6 ... Tuyer, 7 ... Blow pipe, 10 ... Hot air, 11 ... Powder blowing raw material θ …… Taper angle of burner tip θt …… Installation angle of tuyere θR …… Aperture angle of powder injection lance l …… Lance position from tip of tuyere D ₁ …… Lance diameter D ₂ …… Diameter of taper tip L ₁ ...... Distance from the boundary between blast furnace tuyere and blow pipe to the tip of the lance

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliography Sho 58-189147 (JP, U) Japanese Patent Sho 39-806 (JP, B1)

Claims (1)

[Claims] 1. A powder material blowing lance which penetrates through a wall of a hot air blowing blow pipe connected to a blast furnace tuyere and obliquely projects to the center of the tuyere. The groove surface has a groove hole surface whose angle is in the range of 0 ° ± 30 ° with respect to the tuyere axis, and the center of the lance opening is on the tuyere axis and the distance from the tip of the tuyere. A lance for injecting blast furnace powder raw material, wherein l satisfies the condition defined by the following formula. Where, Wf: powder injection rate (kg / sec) Ustr: blast air velocity (m / s) Wa: mass flow rate of air (kg / m ² · sec) De: eddy diffusion coefficient (m ² / sec) l: Distance from tuyere tip to center of lance opening (m) D: Tuyere diameter (m)