JPH01195231A - Fluidized-bed reducing device for iron ore - Google Patents

Abstract

PURPOSE:To efficiently reduce iron ore in a bent downcomer and to improve the productivity of a fluidized-bed reducing furnace by collecting the iron ore grains generated in the furnace, returning the grains to the furnace through the downcomer, and providing a means for blowing a reducing gas into the downcomer. CONSTITUTION:The iron ore grains discharged from the outlet of the fluidized- bed reducing furnace 1 are collected by a cyclone 2, and stored in a hopper 3. The grains are sent downward to an iron ore feeder 5, then sent downward to an iron ore return device 9 through bent downcomers 6 and 7 while forming a moving bed, and returned to the furnace 1. A reducing gas blowing port 8 is provided at the midway of the downcomer 6. A reducing gas 11 is sent upward in the downcomer 6, and introduced into the furnace 1 from a specified position of the feeder 5 through a lead pipe 10. Meanwhile, a working gas is blown into the feeder 5 from the return device 9, and introduced into the furnace 1 through the lead pipe 10. The solid iron ore grains descend dispersedly in the downcomer 6, and are brought into sufficient contact with the reducing gas ascending in the downcomer 6 and efficiently reduced.

Description

[Detailed Description of the Invention] [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, etc. have been conventionally adopted. has been done.

As an alternative to such conventional hot metal production techniques, the smelting reduction method is attracting attention. The smelting reduction furnace used in this method was developed for the purpose of producing molten iron-based alloys using smaller-scale equipment without being restricted by the raw materials used.

The present inventors previously proposed one of such melt reduction methods in JP-A-61-e4goy.

Furthermore, the present inventors have disclosed in Japanese Patent Application No. 61-286599 that the reducing gas blown into the fluidized bed reduction furnace forms three layers: a high-speed fluidized bed, a bubbling fluidized bed, and a packed bed. A device to obtain circulating flow characteristics was proposed.

FIG. 5 shows the flow.

That is, an external particle circulation device is attached to the fluidized bed reduction furnace, and a cyclone 2 is connected to the outlet provided at the top of the fluidized bed reduction furnace 1 to capture the fine particles that are scattered along with the reducing gas 11. .

A hopper 3 for temporarily storing the captured particles is connected to the lower part of the cyclone 2, and a predetermined amount of the captured particles is temporarily stored in the hopper 3 and returned to the fluidized bed reduction furnace 1 by a circulating cutting device 16.

On the other hand, there are a plurality of gas outlets 23 inside the fluidized bed reduction furnace 1.
．． 21 is formed. These gas outlets 23, 21
A bubbling fluidized bed 22 is formed in the middle part of the particle circulation device, and a circulation outlet of the external particle circulation device is provided in this bubbling fluidized bed 22.

In addition, a packed bed 17 is formed at the bottom of the fluidized bed reduction furnace 1,
A furnace bottom blowing nozzle 18 is provided within the packed bed 17 .

In the figure, 24 is a cut-off valve for charging raw materials 25 such as fine ore and limestone into the fluidized bed reduction furnace 1, 19, 26, and 27 are flow rate control valves for adjusting the amount of reducing gas blown out, and 15 is a Fine-grained reduced ore cutting valve 20 is a fine-grained reduced ore cutting valve.

Next, raw materials 25 such as fine ore and limestone are charged into the fluidized bed reduction furnace 1 from the cutting valve, and the reducing gas 11 is passed through the flow rate control valves 19 and 28.
．． When the gas is blown from the gas outlet 23.21.18 through the gas blowing nozzle 27, the blowing amount of all the gas blowing nozzles is added to the uppermost gas blowing nozzle 23, and the final velocity of the fine raw material particles is lower than the final velocity Ut. The speed becomes high, and the fine raw material particles are scattered above the fluidized bed reduction furnace while reacting with the reducing gas.

On the other hand, coarse grained raw materials have a higher terminal velocity Ut than fine grained raw materials, so they do not scatter at the gas outlet 23, and the bubbling fluidized bed 2 located between the two gas outlets 23 and 21
2, the coarse particles descend to the packed bed 17 at the bottom of the furnace.

The coarse particles in the packed bed 17 are reliably reduced by a proper flow rate of reducing gas through the furnace bottom blowing nozzle 18 located at the bottom of the furnace, and the coarse reduced ore is discharged from the cutting valve 20 to proceed to the next process. Sent.

On the other hand, the fine particles are scattered in the fluidized bed reduction furnace 1, captured by the cyclone 2 from the outlet at the top of the furnace, and circulated through the bubbling fluidized bed 22 via the hopper 3 and the circulation cutting device 1B, where they are reduced again.

The fine-grained reduced ore that has achieved the desired reduction is discharged from the cut-off valve 15 and sent to the next process.

[Problem to be solved by the invention H In a reduction device in which an external particle circulation device is attached to a fluidized bed reduction furnace, in the fluidized bed reduction furnace, reducing gas and iron ore are effectively catalytically reacted to perform reduction. , a reduction reaction cannot be expected in the downcomer pipe that connects the hopper and the circulating cutting device.

For this reason, if you try to actively blow reducing gas into the downcomer to promote the reduction reaction, the vertical downcomer will not work as shown in Figure 4 (a).
), the generation of large bubbles in the downcomer causes slagging, which impedes the downward transport of particles and causes variations in the amount of particle circulation. It cannot promote reduction reactions.

Furthermore, the upflow of the reducing gas that rises in the downcomer pipe and flows into the cyclone from the lower part of the cyclone deteriorates the collection efficiency of the cyclone, resulting in poor iron ore yield.

There is a method of using an inclined downcomer pipe to prevent slagging, but in this method, the injected reducing gas is
As shown in b), since the iron ore flows above the inclined downcomer separately from the iron ore, a good solid-gas contact reaction is not carried out, and therefore reduction is not carried out efficiently.

Moreover, upflow to the cyclone cannot be prevented even in an inclined downcomer pipe.

Therefore, the present invention also applies to the downcomer pipe of the external particle circulation device.
The present invention provides an iron ore fluidized bed reduction device that efficiently and stably reduces iron ore.

[Means for Solving the Problems] In the present invention, a cyclone 2 is provided at the outlet of the fluidized bed reduction furnace 1 to collect iron ore particles generated within the fluidized bed reduction furnace 1.

Next, an iron ore cutting device 5 for cutting out iron ore particles is connected to the cyclone 2. A bent descending pipe 6.7 is provided to connect the iron ore extraction device 5 and transport the iron ore particles.

Next, an iron ore return device 9 for returning iron ore particles to the fluidized bed reduction furnace 1 is connected to the bent downcomers 6 and 7. Then, the device for transferring iron ore particles such as the bent downcomer pipe 6 and/or the iron ore cutting device 5 and the fluidized bed reduction furnace 1 are connected to the pressure conduit 10.
Connect at.

[Function] Iron ore particles generated in the fluidized bed reduction furnace 1 are collected by the cyclone 2 disposed at the outlet of the fluidized bed reduction furnace 1. The collected iron ore particles are transferred to an iron ore cutting device 5 connected to the cyclone 2, and from this cutting device 5 to a bent downcomer pipe 6.
The iron ore is transferred to the iron ore return device 9 via the iron ore 7, and then returned to the fluidized bed reduction furnace 1.

To be more specific, the iron ore particles discharged from the iron ore extraction device 5 and flowing out into the bent downcomer pipes 6 and 7 are separated into iron ore particles at the bent part of the bent downcomer pipe 6, as shown in FIG. 4(C). The group descends while dispersing due to the dispersion phenomenon, and the reducing gas blown into the bent downcomer pipe 6 rises without forming large bubbles, so the iron ore descends stably and is efficient due to a good solid-gas contact reaction. will be returned to you.

Further, the reducing gas rising in the bent downcomer pipe 6 passes through the pressure pipe 10 disposed in the bent downcomer pipe 6, the iron ore cutting device 5, etc.
By flowing into the fluidized bed reduction furnace 1, deterioration of the particle collection efficiency of the cyclone can be prevented, so that the reducing gas can be actively blown into the bent downcomer pipe 6.

Furthermore, at the inclined part of the bent downcomer pipe, the powder added to the iron ore is reduced due to the slope effect, and at the bent part, particle movement becomes active due to the impact and dispersion effect of iron ore particles, preventing the occurrence of sticking and dispersing the iron ore. Since the downward transportability and circulating fluidity of the stones are maintained, stable circulating fluidic reduction can be performed.

Note that a plurality of gas inlets 8 and a plurality of solid-gas separators 12 are provided in the middle of the bent downcomer pipe 6, and the solid-gas separators 12 and the fluidized bed reduction furnace 1 are connected by a pressure impulse pipe 10. The iron ore in the bent downcomer pipe 6 can be reduced by high-quality reducing gas, the gas flow rate rising in the bent downcomer pipe 6 can be suppressed, and the downward transportability of the iron ore can be stabilized.

[Example] In FIG. 1, a reducing gas 11 is blown into a fluidized bed reduction furnace 1 at a superficial velocity increased to such an extent that iron ore is scattered within the furnace. The scattered iron ore particles are discharged from the outlet of the fluidized bed reduction furnace 1 together with the exhaust gas.

The discharged iron ore particles are collected by a cyclone 2 provided at the outlet of the fluidized bed reduction furnace 1 and temporarily stored in a hopper 3 located below the cyclone 2.

Next, the iron ore particles are transferred from the hopper 3 to the iron ore cutting device 5.
The iron ore particles cut out from the iron ore cutting device 5 form a moving layer in the bent downcomer pipe 6.7 and flow down to the iron ore return device 9. is returned to the fluidized bed reduction furnace 1.

On the other hand, a reducing gas inlet 8 provided in the middle of the bent downcomer pipe 6
The reducing gas 11 blown from the iron ore extraction device 5 rises in the bent downcomer pipe 6 and flows into the fluidized bed reduction furnace 1 from a predetermined position of the iron ore cutting device 5 via the pressure impulse pipe 10.

Furthermore, the working gas blown into the iron ore cutting device 5 from the iron ore return device 9 also flows into the fluidized bed reduction furnace 1 via the pressure guiding pipe 10 .

At this time, the iron ore particles disperse and descend within the bent downcomer pipe 6, making good solid-gas contact with the reducing gas blown in from the reducing gas inlet 8 and rising within the bent downcomer pipe 6, resulting in efficient reduction. do.

In this way, the iron ore particles are reduced while circulating between the fluidized bed reduction furnace 1 and the external particle circulation path. here,
A bent downcomer refers to a downcomer pipe in which two inclined pipes are connected at a bent part, and the shape of the bent part is not limited.

A hopper 3 located below the cyclone 2 and a downcomer pipe 4 connecting the hopper 3 and the iron ore extraction device 5 are filled with flowing iron ore and sealed with powder, and are bent downward. The reducing gas injected from the middle of the pipe 6 and the gas injected into the iron ore extraction device 5 and the iron ore return device 9 as working gas flow into the fluidized bed reduction furnace 1 via the impulse pipe 10, so that the lower part of the cyclone 2 Since there is no upflow from the cyclone 2, there is no adverse effect on the particle collection efficiency of the cyclone 2.

Cyclone 2 allows the injected gas to escape through the impulse pipe.
Needless to say, powder sealing between the iron ore cutting device 5 and the iron ore extraction device 5 is reduced.

In addition, powder sealing is also performed in the bent downcomer pipe 7, and the fluidized reducing gas blown from the lower part of the fluidized bed reduction furnace 1 flows into the particle circulation path, and the fluidized bed reduction furnace 1 is operated and
has no adverse effect on

FIG. 2 shows that a plurality of reducing gas inlets 8 and a plurality of solid-gas separators 12 are provided in the middle of the bent downcomer pipe 6 in FIG. An example in which the parts are connected by a pressure pipe 10 is shown.

The reducing gas injected from the reducing gas inlet 8 is separated from iron ore in a solid-gas separator 12, and flows into the fluidized bed reduction furnace 1 via a pressure impulse pipe 10.

At this time, the flow of the reducing gas is controlled by adjusting the pressure regulating valves 13, 14, respectively.

FIG. 3 shows details of the iron ore extraction device 5 in FIG. 1 as an example of an iron ore extraction device.

Iron ore stored in a downcomer pipe 4 connecting a hopper 3 and an iron ore cutting device 5 shown in FIG. 1 is cut out by being blown away by working gas a'.

The reducing gas a that has ascended through the bent downcomer pipe 6 and the working gas a' are separated into solid and gas in the space C, and only the gas flows into the fluidized bed reduction furnace 1 through the pressure impulse pipe 10. Also, the second
The iron ore extraction device 5 may be used as the solid-gas separator 12 in the figure.

[Effects of the Invention] As described above, the present invention makes it possible to effectively utilize the dead space of the reduction reaction in the particle downcomer of the particle circulation system of the iron ore fluidized bed reduction apparatus, thereby improving the productivity of the reduction apparatus.

Furthermore, since there is no generation of coarse clusters due to slagging and sticking, the amount of particles transferred is stabilized, control of circulation 2 and reduction rate is stabilized, and controllability as a reduction device is improved.

Furthermore, since there is no upflow of gas from below the cyclone, the collection efficiency in the cyclone is high and the product yield is improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the basic configuration of the iron ore fluidized bed reduction apparatus of the present invention, and FIG. 2 is a detailed explanatory diagram of the downcomer section of the present invention.
Figure 83 is an explanatory diagram of the iron ore extraction device, Figure 4 (a), (
b) and (c) are vertical downcomers, inclined downcomers, respectively;
Explanatory diagram of the action showing gas flow in a bent downcomer, No. 5
The figure is an explanatory diagram of a conventional iron ore fluidized bed reduction apparatus. 1...Fluidized bed reduction furnace 2...Cyclone 3.
... Hopper 4 ... Downcomer pipe 5 ... Iron ore cutting device 6.7 ... Bent downcomer pipe 8 ... Reducing gas inlet 9 ... Iron ore return device 10 ... Impulse pipe it. ...Reducing gas 12...Solid gas separator 13.14...Pressure control valve type
Person Patent Attorney Tatsuo Chanoki Figure 5

Claims (1)

[Claims] 1. A cyclone (2) for collecting iron ore particles generated in the fluidized bed reduction furnace (1) is disposed at the outlet of the fluidized bed reduction furnace (1), and the cyclone (2) An iron ore cutting device (5) for cutting out the iron ore particles is connected to the iron ore cutting device (5).
A bent downcomer pipe (6) for transferring iron ore particles is connected to the iron ore return device (6) for returning the iron ore particles to the fluidized bed reduction furnace (1) to the bent downcomer pipes (6) and (7). 9), and a device for transferring iron ore particles such as the bent downcomer pipes (6), (7) and/or the iron ore cutting device (5), and the fluidized bed reduction furnace (1) are connected to the pressure pipe (1). 10) An iron ore fluidized bed reduction apparatus, characterized in that the iron ore fluidized bed reduction apparatus is connected to 2. Claim 1, characterized in that a reducing gas inlet (8) and a solid-gas separator (12) are arranged at predetermined positions of the bent downcomer pipes (6) and (7). iron ore fluidized bed reduction equipment.