JPS63140020A - Fluidized bed reducing device for iron ore - Google Patents

Abstract

PURPOSE:To accelerate high-speed fluidized reduction reaction and to improve the efficiency of reduction by providing an external particle circulating device to a fluidized bed reduction furnace and providing expanding and reducing parts to the furnace to increase the amt. of the stagnating particles. CONSTITUTION:A cyclone 31 is connected to the upper part of the fluidized bed reduction furnace 6 to capture the fine particles entrained in a reducing gas 11 and thereafter, the gas is returned through a hopper 33 to the furnace 6. The reducing part 30 and the expanding 31 are formed in the height direction of the furnace 6 to introduce the reducing gas 11 into the furnace 6 by which the iron ore particles are fluidized at high speed. The concn. of the particles is improved by the vortexes generated in the expanding part 31 and the decrease in the superficial velocity of the gas at this time. The slip speed of the reducing gas and the particles is increased by the vortexes, by which the reactivity of the iron ore and the reducing gas is improved and the rate of utilizing the reducing gas is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an iron ore reduction apparatus for reducing iron ore in a fluidized bed reduction furnace for use in a smelting reduction method, a blast furnace method, etc.

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

In the method using a blast furnace, a large amount of coke is used as a heat source and a reducing agent, and the iron ore, which is the iron source, is usually sintered to improve air permeability and reducing properties in the furnace, and is processed as sintered ore. It is charged into the blast furnace. For this reason, the blast furnace method requires coke oven equipment for dry distilling highly caking coal and sintering equipment for producing sintered ore. Therefore, the blast furnace method requires a large amount of energy and labor as well as a large amount of equipment cost. For this reason, the blast furnace method has the disadvantage of high processing costs.

Furthermore, the supply of strong coking coal is unstable because there is only a small amount of it available worldwide and its distribution is regionally uneven.

On the other hand, the method of reducing iron ore using a shaft furnace requires pretreatment to pelletize the iron ore, and has the disadvantage that it consumes a large amount of reducing agent, expensive natural gas, etc. as a heat source.

As an alternative to such conventional hot metal production technology, the smelting reduction scouring 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.

As an example of the above-mentioned melt reduction method, the present inventor previously proposed a method consisting of the flow shown in FIG.
It is proposed as No. 56.

According to this method, hot metal is produced as follows. That is, iron ore 1 and limestone 2 are heated in a fluidized bed preheating furnace 3 by heat generated by a combustion reaction between coal 4 and air 5. As a result, limestone 2 (CaCO2) becomes quicklime (CaCO2).
b) and is supplied to the fluidized bed reduction furnace 6.

In the fluidized bed reduction furnace 6, coal 7 and oxygen or oxygen-containing gas are blown into the preheated ore and quicklime in a fluidized state. This coal 7 exchanges heat with the preheated ore in the fluidized bed reduction furnace 6 and is thermally decomposed by partial combustion due to reaction with oxygen. As a result, the coal 7 generates reducing gas, and
It becomes char 9.

On the other hand, the gas generated in the melting reduction furnace 10 or the reducing gas 11 obtained by decarboxylating the gas is transferred to the fluidized bed reduction furnace 6.
700-900 by heat exchange with fuel gas 12 from
After being heated to 0.degree. C., it is blown into a fluidized bed reduction furnace 6. The reducing gas 11 blown into the fluidized bed reduction furnace 6 is mixed with the reducing gas generated by thermal decomposition of the coal 7, reduces the hot powdery iron ore in a fluidized state, and produces reduced *13.

In addition, the quicklime 14 produced in the fluidized bed preheating furnace 3 is charged into the fluidized bed reduction furnace 6 together with the preheated ore, and the gas in the fluidized bed reduction furnace 6 is desulfurized.Then, the quicklime 14 is It is discharged from the fluidized bed reduction furnace 6 together with the reduced ore 13 and the char 9.

To the reduced ore 13, char 9, and quicklime 14 obtained in this way, carbonaceous materials such as coal and coke necessary for the heat balance in the smelting reduction furnace 10 are added from the outside and kneaded. The mixture is formed into briquettes 16 by an agglomeration device 15 such as a brisket machine, and then charged into the smelting reduction furnace 10 by a charging device 17.

This melting reduction furnace lO is supplied with oxygen 1 from the top blowing lance 18.
9 is blown toward the bath, and the bottom blowing tuyere 2
Oxygen and carbonaceous material are blown into the bath from zero. Then, the charcoal material contained in the briquette 16, the bottom blowing tuyere 20
The carbonaceous material such as coke 21 supplied from the charging device 17 is blown in with oxygen from the top blowing lance 1.
It reacts with the oxygen supplied from 8 and generates a large amount of heat in the melting reduction furnace 10. Due to this generated heat, Brikent 1
The reduced ore 13 in 6 is dissolved, and the reduction progresses to become hot metal.

On the other hand, the gangue in the reduced ore 13 reacts with the carbon material and the quicklime 14, and slag 23 is generated. This slag 23 is stored in the melting reduction furnace 10 and increases in amount as time passes, so the slag 23 is intermittently or continuously discharged outside the furnace.

(Problems to be solved by the invention) In this smelting reduction method, as is clear from the development process, it is important to expand the range of usable raw materials, improve the efficiency of heat recovery, and improve the smelting reduction furnace. The future challenge is how to accelerate the scouring reaction.

However, in the high-speed fluidized bed used in iron ore reduction equipment, the distribution of iron ore in the furnace becomes more dilute as the furnace height increases. The rate decreases exponentially with the height of the furnace.

Therefore, even if iron ore is reduced under such conditions, the reactivity between the iron ore and the reducing gas is poor, the reduction rate is low, the gas utilization rate is low, and the scale of production equipment is increased.

Therefore, in the present invention, we decided to change the shape of the fluidized bed reduction furnace itself to increase the internal retention amount of particles in the fluidized bed reduction furnace, thereby promoting the high-speed fluid reaction by ensuring the particle concentration in the furnace height direction. .

(Means for Solving the Problems) The iron ore reduction apparatus of the present invention includes an external particle circulation device attached to a fluidized bed reduction furnace in equipment for producing reduced ore used in the smelting reduction method. A plurality of enlargement/contraction parts are provided inside the furnace in the direction of the furnace height.

(Function) The present invention is configured as described above, and the fluidized bed reduction furnace is equipped with powder ore.
A raw material such as coal is charged, and reducing gas is blown through a gas injection nozzle to fluidize the raw material particles at high speed.

Particles are scattered along with the reducing gas and flow at high speed in the fluidized bed reactor, but the fluidized bed reduction reactor has multiple expansion/contraction sections in the furnace height direction, and the generation of vortices in these enlarged sections causes the particles to The downward flow is increased, causing collisions between particles and walls, friction, etc., and a brake is applied to the scattering speed of particles.

In addition, due to the expansion, the superficial velocity of the reducing gas decreases and the particle scattering rate decreases, so the amount of particles staying in the fluidized bed reduction furnace increases, and the porosity increases as shown by the dotted line in Figure 3. Improvements can be made.

In addition, by forming a reduced part and an enlarged part in the fluidized bed reduction furnace 6, the slip speed of particles and reducing gas increases, and the particle concentration increases due to a significant improvement in the porosity in the furnace.
It can promote fast flow reduction reaction.

(Example) An example of the present invention will be described in detail below with reference to a schematic diagram of the basic configuration shown in FIG.

A reduced portion 30 and an enlarged portion 31 are formed in the furnace height direction of the fluidized bed reduction furnace 6.

The embodiment shown in FIG. 1 has a structure in which the middle of the fluidized bed reduction furnace 6 is enlarged, and the embodiment in FIG. 2 has a structure in which the middle of the fluidized bed reduction furnace 6 is reduced.

Note that in this embodiment, the diameters of the respective reduced portions 30 or the diameters of the enlarged portions 31 are made equal; however, the diameter is not limited to this, and these diameters may be gradually enlarged or reduced. Although the sizes of the reduced portion 3o and enlarged portion 31 are not particularly limited, in the embodiment shown in FIG.
The diameter of the reduced part 30 is d, the height is h5, and the diameter of the enlarged part 31 is D.
, the height is H, then D/d-1 Imaichi, h-d/2, D-
It is formed by the relationship d. Further, the enlargement angle is 45°.

The configuration of the external particle circulation device attached to the fluidized bed reduction furnace is such that a cyclone 32 is connected to the outlet provided at the top of the fluidized bed reduction furnace 6 to capture the fine particles that are scattered along with the reducing gas 11. .

The trapped particles are returned to the fluidized bed reduction furnace 6 through a hopper 33 in the lower part of the cyclone 32, which temporarily stores the captured particles.

On the other hand, gas outlets are formed at appropriate positions in the fluidized bed reduction furnace 6 to introduce reducing gas 11.

When the reducing gas 11 is introduced into the furnace of the fluidized bed reduction furnace 6, the iron ore contained in the fluidized bed reduction furnace 6 is fluidized at high speed by the reducing gas, and the zero particles are scattered together with the reducing gas. Although the fluidized bed flows at high speed, the fluidized bed reduction furnace 6 is formed with a contracting section 30 and an expanding section 31, and due to fluctuations in the cross-sectional area of the furnace, vortices are generated at the expanding section and the superficial gas velocity is reduced. The concentration of particles is improved by the reduction, and the slip velocity between the reducing gas and the particles is increased by this vortex flow, so that the reactivity between the iron ore and the reducing gas is improved and the reduction rate gas utilization rate is also increased.

The above-mentioned slip velocity refers to the difference between the superficial gas velocity and the particle rising velocity.

Note that this equipment is not limited to those used for producing reduced ore for smelting reduction. It is also possible to reduce iron ore and supply it to a blast furnace.

(Effects of the Invention) As described above, in the present invention, since the reduction part and the enlargement part are formed in the fluidized bed reduction furnace, the internal circulation amount of iron ore in the fluidized bed reduction furnace is improved. Coupled with an increase in the slip speed of the reducing gas 11 and particles in the furnace, it is possible to promote a high-speed flow reduction reaction, promoting reduction efficiency, and creating a compact reduction equipment with a high reaction rate and improved gas utilization rate. It has an equivalent effect that can provide the following.

Furthermore, when used in a blast furnace method, it is possible to improve the productivity of the blast furnace and to downsize ancillary equipment such as sintering equipment and coke oven equipment.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the basic configuration of the present invention, Fig. 2 is an explanatory diagram showing another embodiment of the invention, and Fig. 3 is the height of the furnace height of the fluidized bed reduction furnace and the distribution of iron ore. FIG. 4 is an explanatory diagram showing an outline of the melt reduction method previously proposed by the present inventors. 6 is a fluidized bed reduction furnace, 11 is a reducing gas, 30 is a reduction section, 3
1 is an enlarged part, 32 is a cyclone, and 33 is a hopper. Spear 1 Picture Spear 2 Picture Spear 3 Picture 1 Sora Q5 Missing 4 Eyes Amended Document for Busy Procedures January 13, 1985 Commissioner of the Patent Office Black 1) Akio Tono 1, Indication of Case Patent Application No. 1986-286600 2 , Title of the invention: Iron ore fluidized bed reduction device 3, Person making the amendment Relationship to the case Patent applicant (665) Nippon Steel Corporation 4, Agent 1-1-18 Toranomon, Minato-ku, Tokyo 5, Amendment Contents of the Amendment As stated in Column 6 of the Scope of Claims in the Target Specification, Contents of Amendment Application Number: Japanese Patent Application No. 61-286600 The scope of claims in the specification is amended as follows. rClaims

Claims (1)

[Claims] A fluidized bed reduction of iron ore, which is a facility for producing reduced ore, characterized in that a fluidized bed reduction furnace is equipped with an external particle circulation device, and a plurality of expansion/contraction sections are provided in the furnace height direction. Device.