JP2897392B2 - Preliminary reduction furnace in smelting reduction facility of iron ore - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a preliminary reduction furnace in a smelting reduction facility for iron ore.

[Conventional technology]

In the smelting reduction of iron ore, it is economical to use a smelting reduction furnace and a fluidized bed type pre-reduction furnace, and to use the exhaust gas generated in the smelting reduction furnace as a fluidized bed of the pre-reduction furnace and as a reducing gas Above. As the fluidized bed, a bubbling fluidized bed is particularly advantageous because it has a high degree of technical perfection and can suppress powdering caused by preheating and reduction of the ore.

This pre-reduction furnace is provided with a dispersion plate having a number of nozzle holes (gas through holes) for gas ejection therein, and iron ore is charged into a pre-reduction chamber formed above the dispersion plate. Then, exhaust gas (reducing gas) from the smelting reduction furnace is introduced into a gas injection chamber (wind box) below the dispersion plate. This reducing gas is
It is blown out to the upper pre-reduction chamber through the nozzle holes of the dispersing plate, whereby a fluidized bed is formed, and the pre-reduction and pre-heating of the iron ore are performed.

[Problems to be solved by the invention]

In such a pre-reduction furnace, the adhesion of dust contained in the exhaust gas to the dispersion plate becomes a major problem.

That is, the exhaust gas generated from the smelting reduction furnace contains a large amount of dust. Of these, the fine dust of 10 μm or less cannot be removed by a dust remover such as a cyclone in many cases, and the exhaust gas containing such fine dust Is directly introduced into the preliminary reduction furnace.

Since the dust contains a large amount of alkali compounds such as S, Na, and K, the dust has a sticky property in an exhaust gas having a temperature exceeding 900 ° C. It will adhere to the inner surface of the nozzle hole.
In particular, the exhaust gas introduced into the gas injection chamber is contracted when passing through the nozzle hole, and the gas flow rate in the nozzle hole becomes extremely high (flow rate: several tens m / sec or more). Particularly, it is easily adhered firmly. Such deposits due to dust gradually grow, and eventually hinder the smooth flow of the reducing gas, so that an appropriate fluidized bed cannot be formed. FIG. 4 shows such a situation, wherein 1 is a fluidized bed, 2 is a dispersion plate,
Reference numeral 3 denotes a gas blowing chamber below the dispersion plate, and reference numeral 4 denotes dust that has adhered and grown.

The present invention has been made in view of such a conventional problem, and adheres dust to the dispersion plate, particularly to the inner surface of the nozzle hole.
It is an object of the present invention to provide a preliminary reduction furnace capable of effectively preventing growth.

[Means for solving the problem]

Therefore, the present invention provides a fluidized bed type pre-reduction furnace having a dispersion plate having a large number of nozzle holes penetrating therein, wherein the nozzle holes are formed of a metal cylinder having a closed double tube structure, and a plurality of nozzle holes are formed. As a group of nozzle holes, the metal cylinders of the plurality of nozzle holes constituting the nozzle hole group are sequentially connected by a communication pipe communicating with the inside of the double pipe structure, thereby being constituted by a plurality of metal cylinders and a communication pipe. A flow path is formed, and a cooling fluid introduction pipe is connected to the metal pipe at one end of the flow path, and a cooling fluid discharge pipe is connected to the metal pipe at the other end of the flow path.

[Action]

The plurality of nozzle holes provided in the dispersion plate are divided into one or more groups, and a cooling fluid flow path including a plurality of metal cylinders and a connecting pipe is formed for each group. The cooling fluid (eg, N ₂ gas, water, oil, etc.) supplied through the inlet pipe connected to the metal pipe on one end side of each flow path is supplied to the metal pipe of each nozzle hole forming a group via the connecting pipe. After flowing inside (inside the double pipe structure) and cooling the inner surface of the nozzle hole and the inlet of the nozzle hole, it is discharged to the outside of the dispersion plate through a discharge pipe connected to a metal tube at the other end of the flow path. Due to the cooling by the cooling fluid, the temperature of the inner surface of each nozzle hole formed by the metal cylinder decreases, and even if dust in the reducing gas adheres to these surfaces, it rapidly solidifies and is easily separated. Usually, the temperature of the reducing gas introduced into the preliminary reduction furnace is about 1000 to 1200 ° C, but by cooling the surface temperature of the inner surface of the nozzle hole to about several hundred degrees Celsius, the dust can be easily separated. Become.

〔Example〕

1 to 3 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view, FIG. 2 is a schematic view showing a horizontal section of a dispersion plate, and FIG. It is an expanded longitudinal sectional view.

In the figure, reference numeral 5 denotes a dispersion plate which vertically partitions the inside of the preliminary reduction furnace, and reference numeral 6 denotes a plurality of nozzle holes penetrating through the entire surface of the dispersion plate. The pre-reduction furnace partitioned by the dispersion plate 5 constitutes a pre-reduction chamber 12 above and a gas injection chamber 13 below. The gas injection chamber 13 is provided with a gas inlet 14 to which a gas conduit 15 from the smelting reduction furnace is connected. An ore outlet 16 is provided at the center of the dispersion plate, and an outlet pipe 17 penetrating the gas injection chamber is connected to the outlet 16.

As shown in FIG. 3, each of the nozzle holes 6 is a metal tube 8 of a closed double tube structure embedded in a refractory dispersing plate main body 7.
It consists of.

Such nozzle holes are divided into the nozzle hole group A ₁ to A ₆ comprising a plurality of nozzle holes 6 as shown in FIG. 2, for each nozzle hole group A, a plurality of nozzle holes constituting these metal The tubes 8 are connected in series by a connecting pipe 9 communicating with the inside of the double pipe structure. As a result, the nozzle hole groups A ₁ to
For each A ₆ , a flow path B ₁ to a plurality of metal cylinders 8 and a connecting pipe 9.
B ₆ is formed. A cooling fluid inlet 10 is provided in the metal cylinder 8 at one end of each flow path B, and a cooling fluid outlet 11 is provided in the metal cylinder 8 at the other end of the flow path B. The fluid introduction pipe 18 and the discharge pipe 19 are connected.

In addition, the nozzle holes 6 of the dispersion plate 5 can be divided into one or two or more arbitrary number of nozzle hole groups A. For convenience in manufacturing the dispersion plate, for example, the dispersion plate is divided into a plurality of blocks in the circumferential direction. And it is preferable that the plurality of nozzle holes for each block be one nozzle hole group.

 Next, the operation of the above embodiment will be described.

For each of the nozzle hole groups A _{1 to} A ₆ , a cooling fluid such as N ₂ gas is supplied into the flow paths B _{1 to} B ₆ through the introduction pipe 18. The cooling fluid flows through the connecting pipe 9 into the metal cylinder 8 (inside the double pipe structure) of each of the nozzle holes 6 constituting the group, and cools the inner surface of the nozzle hole and the inlet of the nozzle hole in the middle thereof. It is discharged out of the dispersion plate through a discharge pipe 19 connected to the metal tube 8 on the end side. Due to the cooling action by the cooling fluid, the temperature of the inner surface of each nozzle hole 6 formed by the metal cylinder 8 decreases, and even if dust in the reducing gas adheres to these surfaces, it quickly solidifies and easily separates. Will be.

〔The invention's effect〕

According to the present invention described above, dust is effectively prevented from adhering and growing on the inner surface of the nozzle hole and the inlet of the nozzle hole of the dispersion plate, so that the exhaust gas can be stably blown into the fluidized bed. be able to.

[Brief description of the drawings]

1 to 3 show an embodiment of the present invention.
FIG. 1 is a longitudinal sectional view, FIG. 2 is a drawing schematically showing a horizontal section of a dispersion plate, and FIG. 3 is an enlarged longitudinal sectional view of a nozzle hole.
FIG. 4 is an explanatory view showing the state of adhesion of dust in a conventional preliminary reduction furnace. In the figure, 5 is a dispersion plate, 6 is a nozzle hole, 8 is a metal cylinder,
9 connecting tube, 18 inlet tube, exhaust tube 19, A ₁ to A ₆ is the nozzle hole group, B ₁ .about.B ₆ is the flow path.

Continuation of the front page (72) Inventor Yoshiyuki Kitano 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Sakae Arakawa 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Tatsuro Ariyama 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) C21B 11/00-13/14 F27B 15 / 00-15/20

Claims (1)

(57) [Claims] 1. A fluidized bed type pre-reduction furnace having a dispersion plate having a large number of nozzle holes penetrating therein, wherein the nozzle holes are constituted by a metal cylinder having a closed double tube structure, and a plurality of nozzle holes are formed. As one nozzle hole group, a metal tube of a plurality of nozzle holes constituting the nozzle hole group is sequentially connected by a communication tube communicating with the inside of the double tube structure, thereby being constituted by a plurality of metal tubes and a communication tube. A flow path is formed, and a cooling fluid introduction pipe is connected to the metal pipe at one end of the flow path, and a cooling fluid discharge pipe is connected to the metal pipe at the other end of the flow path. Preliminary reduction furnace in smelting reduction equipment.