JPH0723492B2 - Iron ore fluidized bed reduction device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for reducing iron ore in a fluidized bed preliminary reduction furnace for use in a smelting reduction method.

[Prior Art] In order to reduce iron ore to produce hot metal, a method of using a blast furnace, a method of melting iron ore reduced in a shaft furnace in an electric furnace, and the like have been conventionally adopted.

The smelting reduction method has been attracting attention as an alternative to such conventional hot metal production technology. The smelting reduction furnace used in this method was developed for the purpose of producing a molten iron-based alloy by a smaller-scale facility without being restricted by the raw material used.

The present inventors previously proposed one of such smelting reduction methods in Japanese Patent Laid-Open No. 61-64807.

Furthermore, in the Japanese Patent Application No. 61-286599, the inventors of the present invention formed three layers of a high-speed fluidized bed, a bubbling fluidized bed, and a packed bed by a reducing gas blown into a fluidized bed reduction furnace,
An apparatus for obtaining stable high-speed circulating flow characteristics was proposed.

FIG. 3 shows the flow.

That is, an external particle circulation device is attached to the fluidized bed reduction furnace, and a cyclone 31 is connected to the outlet provided at the upper part of the fluidized bed reduction furnace 6 to capture fine particles that have been scattered along with the reducing gas 11.

A hopper 32 for temporarily storing the captured particles is connected to the lower part of the cyclone 31, and a predetermined amount is temporarily stored in the hopper 32 and returned to the fluidized bed reduction furnace 6 by the circulation cutting device 33.

On the other hand, a plurality of gas outlets 34, 3 are provided in the fluidized bed reduction furnace 6.
5 are formed. A bubbling fluidized bed 36 is formed in the middle of the gas outlets 34, 35, and the bubbling fluidized bed 36 is formed.
A circulation outlet of the external particle circulation device is provided therein.

Further, a packed bed 37 is formed at the bottom of the fluidized bed reduction furnace 6, and a furnace bottom blowing nozzle 38 is provided in the packed bed 37.

In the figure, 39 is a cutoff valve for charging the raw material 25 such as powdered ore and limestone into the fluidized bed reduction furnace 6, 40, 41, 42 are flow rate control valves for adjusting the amount of reducing gas blown out, and 43 is A fine-grained reduction ore cutoff valve, and 44 is a fine-grained reduction ore cutout valve.

Next, the raw material 25 such as powdered ore and limestone is charged into the fluidized bed reduction furnace 6 from the cut-out valve, and the reducing gas 11 is blown from the gas blow-out ports 34, 35, 38 through the flow rate control valves 40, 41, 42. And, above the uppermost gas blowing nozzle 34, the blowing amount of all the gas blowing nozzles is added, and the velocity becomes higher than the terminal velocity Ut of the fine granular raw material particles, and the fine granular raw material particles react with the reducing gas. Meanwhile, it scatters above the fluidized bed reduction furnace.

On the other hand, since the coarse-grained raw material has a higher terminal velocity Ut than the fine-grained raw material, it does not scatter at the gas outlet 34, and is further screened by the bubbling fluidized bed 36 located between the two gas outlets 34 and 35. The coarse particles descend to the packed bed 37 in the lower part of the furnace.

Coarse particles in the packed bed 37 are reliably reduced by a reducing gas at a proper flow rate by a furnace bottom blowing nozzle 38 located in the lower part of the furnace, and coarse particles of reducing ore are discharged from the cut-out valve 44 and sent to the next step. .

On the other hand, the fine particles are scattered in the fluidized bed reduction furnace 6, captured by the cyclone 31 from the outlet at the upper part of the furnace, circulated to the bubbling fluidized bed 36 via the hopper 32 and the circulation cutting device 33, and again reduced.

And the reduction ore of the fine particles that have obtained the desired reduction is cut out by the cut-off valve 43.
And discharged to the next process.

[Problems to be Solved by the Invention] The present invention obtains stable high-speed circulating fluidity characteristics, improves the uniformity of reduction of raw materials having a wide particle size distribution, and promotes efficient reduction reaction. A reduction device is provided.

[Means for Solving the Problems] In the facility for producing reduced ore, the present invention has an external particle circulation device attached to a fluidized bed reduction furnace, and a riser bottom of the fluidized bed reduction furnace and a downcomer bottom of the external particle circulation device. The inclined hearth is installed in the, and the carrier gas blowing port is installed in the inclined hearth,
A bubble flow zone is formed at the bottom of the riser, a fluidized gas inlet is provided above the bubble flow zone, a fine grain outlet is provided at the bottom of the downcomer, a coarse grain outlet is provided at the downstream end of the inclined hearth, and a coarse grain outlet is provided at the bottom of the riser. This is an iron ore fluidized bed reduction device in which intermediate grain discharge ports are provided above in the furnace height direction.

The present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram of the present invention. In the figure, the fluidized bed reduction furnace 1 has a riser 4 and an inlet 13 for a raw material 12 is provided. The external particle circulation device has a cyclone 10 connected to a riser 4 and a downcomer 3.

The present invention uses a tilted hearth 2 at the bottom of the riser 4 and downcomer 3.
This inclined hearth constitutes divided headers 2a, 2b, 2c. The divided headers 2a, 2b, 2c are the flow control valves 15a, 15b,
It has 15c and injects carrier gas 14.

An outlet 6 is provided at the lower end of the downcomer at the upstream end of the inclined hearth 2, and an outlet 5 is provided at the lower part of the riser 4 at the downstream end of the inclined hearth 2.

Further, according to the present invention, a bubbling area is formed in the bottom portion 7 of the riser 4, and the discharge port 9 is provided above this bubble flow area.

Further, a reducing gas injection nozzle group 14 is provided at the bottom of the riser 4.

That is, according to the present invention, the hearth 2 of the fluidized bed circulation furnace 1 is tilted, and the fluidized gas is blown into the furnace from the tilted hearth 2 to flow the furnace body particles. The superficial velocity of the flowing gas in the lower part of the downcomer 3 is made small, and the superficial velocity in the lower part of the riser 4 is adjusted by the flow rate adjusting valve so that the flowing gas is blown from the hearth 2.

Coarse particles with poor fluidity or cluster particles generated in the reduction reaction process are rolled in the inclined hearth and cut out from the coarse particle discharge port 5, and fine particles of semi-reduced ore are discharged from the discharge port 6 provided in the downcomer 3. Cut out from.

In the riser bottom portion 7, the particles are adjusted to a fluidized state of a bubble fluidized bed, which is easily done by the valves 15b and 15c.
That is, by changing the blowing speed, an internal circulation flow is generated,
The coarse particles easily move downward.

In addition, reducing gas is blown into the furnace from the lower region of the raw material inlet 13 through the blowing nozzle 8 to bring the particles into a high-speed flow state, but the intermediate size between the fine particles and the coarse particles of the powdered iron powder is obtained from the bubbling area. Particles overflow from the outlet 9 and are cut out.

Therefore, according to the present invention, the coarse particles are discharged to the outside of the system early by the carrier gas from the divided header of the inclined hearth, and the intermediate particles are well captured from the bubbling region and discharged to the outside of the system.

Another embodiment of the hearth structure at the bottom of the riser is shown in FIG.
Even if the hearths 2-1 and 2-2 are inclined like a brim, the effect is the same.

According to the experiment, coarse particles and intermediate particles of iron ore cause sticking (adhesion) when reduction proceeds due to the reduction reaction.
Or it creates clusters and interferes with flow properties,
The present invention does not address these disorders.

[Effects of the Invention] The present invention can improve the uniformity of reduction even in a raw material having a wide particle size distribution and can efficiently promote the reduction reaction. Further, since the powdered ore having a wide particle size distribution can be positively treated, the powdered ore and steam coal can be used as raw materials, and the cost of hot metal can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall explanatory view of the present invention, FIG. 2 is an explanatory view of another example of the present invention, and FIG. 3 is an explanatory view of a conventional example. 1: Fluidized bed reduction furnace, 2: Inclined hearth 3: Downcomer, 4: Riser 5,6,9: Discharge port, 7: Bubbling bed

Claims (1)

[Claims] 1. A facility for producing reduced ore, wherein a fluidized bed reduction furnace is provided with an external particle circulation device, and a riser bottom of the fluidized bed reduction furnace and a bottom of a downcomer of the external particle circulation device are provided with an inclined hearth, and a tilted bed is provided. A carrier gas injection port is provided in the hearth to form a bubble flow region at the bottom of the riser, a fluid gas injection port is provided above the bubble flow region, a fine grain discharge port is provided below the downcomer, and a coarse gas is provided at the downstream end of the inclined hearth. Iron ore fluidized bed reduction device with a grain discharge port and an intermediate grain discharge port at the bottom of the riser above the coarse grain discharge port in the furnace height direction.