JPS62228873A - Preheated core shifter to fluidized-bed spare reducing furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an apparatus for transferring preheated ore from an ore preheating furnace to a fluidized bed prereduction furnace when iron ore is prereduced for use in a smelting reduction method. .

(Prior art) In order to reduce iron ore to produce hot metal, methods such as using a blast furnace and melting iron ore reduced in a shaft furnace in an electric furnace have been conventionally adopted. A large amount of coke is used as a heat source and reducing agent.In addition, iron ore, which is an iron source, is usually sintered to improve air permeability and reducibility in the furnace, and is converted into sintered ore and used in a 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. The blast furnace method requires not only large equipment costs but also
energy and labor are required. For this reason, the blast furnace method has the disadvantage of high processing costs. Furthermore,
Strong coking coal is scarce worldwide, and its distribution is regionally uneven, making its supply unstable.

On the other hand, the method of reducing iron ore using a shaft furnace requires pre-treatment of turning the iron ore into pellets, and also 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 smelting method is attracting attention. The smelting reduction furnace used in this method is not limited by the raw materials used.
It was developed for the purpose of producing molten iron-based alloys using smaller-scale equipment.

As one such melt reduction method, the present inventors previously proposed a method consisting of the flow shown in FIG. 5 in Japanese Patent Application No. 59484056.

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

In the fluidized bed pre-reduction furnace 6, coal 7 and oxygen or oxygen-containing gas 8 are blown into the preheated ore and quicklime in a fluidized state. Coal 7 is exchanged and thermally decomposed by partial combustion due to reaction with oxygen.As a result, coal 7 generates reducing gas and becomes char 9.

On the other hand, the gas generated in the smelting reduction furnace IO or the reducing gas 11 obtained by decarboxylating the gas is reduced to 700 to 90% by heat exchange with the fuel gas 12 from the fluidized bed preliminary reduction furnace 6.
After being heated to 00°C, it is blown into a fluidized bed pre-reduction furnace 6. Reducing gas 11 blown into the fluidized bed preliminary reduction furnace 6
is mixed with reducing gas generated by thermal decomposition of coal 7, reduces high temperature granular iron ore in a fluidized state, and reduces [
Generate 13.

Moreover, the quicklime 14 produced in the fluidized bed preheating furnace 3 is charged into the fluidized bed prereduction furnace 6 together with the preheated ore, and the gas in the fluidized bed prereduction furnace 6 is desulfurized.

Next, the quicklime 14 is discharged from the fluidized bed preliminary reduction furnace 6 together with the reduced ore 13 and the char 9.

Reduced ore thus obtained 13. Carbon materials such as coal and coke necessary for the heat balance in the smelting reduction furnace 10 are added to the char 9 and quicklime 14 from the outside and kneaded.Next, the mixture is transferred to an agglomeration device 15 such as a briquette machine. After being formed into briquettes 16 by
The material is charged into the melt reduction furnace 10 by the charging device 17 .

In this melting reduction furnace 10, oxygen 19 is blown toward the bath from a top blowing lance 18, and oxygen and carbonaceous material are blown into the bath from a bottom blowing tuyere 20. Then, the charcoal material contained in the briquette 16, the bottom blowing tuyere 2
Carbon material being blown in with oxygen from 0, charging device 17
The carbonaceous materials such as coke 21 supplied from the top blowing lance 18 react with the oxygen supplied from the top blowing lance 18, and generate a large amount of heat in the melting reduction furnace 10.

This generated heat causes the semi-reduced ore 1 in the briquette 16 to
3 melts and reduction progresses to become hot metal 22.

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 its amount increases as time passes.Therefore, the slag 23 is intermittently or continuously discharged out of the furnace.

[Problem that the invention seeks to solve]

In this type of smelting reduction method, as is clear from the development process, low grade fine ore is produced.

It is assumed that steam coal, etc. will be used. Therefore, it is necessary to efficiently collect and reuse the dust generated during the treatment process.

For the purpose of collecting and reusing this dust, JP-A-Sho, 56-
In Publication No. 105409, a cyclone and a gas trap are installed in the external circulation path of a fluidized bed pre-reduction furnace, and suspended dust contained in exhaust gas is collected by a cyclone installed at the furnace outlet, and the collected dust is collected by a gas trap installed below the cyclone. is cut into the furnace through a downcomer pipe.

However, since the gas seal of the gas trap is metal-touch, the seal is incomplete. However,
In the fluidized bed pre-reduction furnace used in the smelting reduction method, reducing gas is blown into the furnace at a superficial velocity high enough to scatter the iron ore charged into the furnace. For this reason, a large fluid pressure drop occurs within the fluidized bed pre-reduction furnace, which is applied to a gas trap provided in the powder transfer path outside the fluidized bed pre-reduction furnace. Therefore, when the seal of this gas trap is incomplete, reducing gas blows out of the system. Furthermore, since the atmosphere is at a high temperature, the gas trap is likely to be deformed, and the gas seal becomes even more complete.

When reducing gas blow-through occurs in the powder transfer path in this way, unreacted reducing gas in the lower part of the fluidized bed pre-reducing furnace directly leaks out of the system, reducing the reducing gas utilization rate. Furthermore, the fluidization state of the powder in the fluidized bed pre-reduction furnace becomes unstable, and the reduction reaction that effectively utilizes the fine ore cannot be carried out smoothly.

Therefore, an object of the present invention is to make the reduction reaction in the fluidized bed pre-reduction furnace smooth by completely sealing the gas in the powder transfer path.

[Means for solving problems]

In order to achieve the object, the preheating ore transfer device of the present invention connects the lower part of the ore preheating furnace and the fluidized bed prereduction furnace in the prereduction equipment consisting of the ore preheating furnace and the fluidized bed prereduction furnace. The present invention is characterized in that a pressure equalizing header is provided in the middle of the pipe, and the pressure equalizing header is connected to the inside of the fluidized bed pre-reducing furnace via a pressure guiding pipe.

[Effect]

In the fluidized bed pre-reduction furnace used in the smelting reduction method,
Fine ore with a large specific gravity is used as the raw material to be fluidized, and the fine ore is dispersed and fluidized at a high particle concentration. Further, in order to promote the reduction reaction, it is necessary to maintain a high pressure atmosphere inside the furnace. For this reason, the fluidization pressure drop of raw material particles in the fluidized bed pre-reduction reactor is extremely large (from several thousand liters of water to tens of thousands of liters of water). Since the gas is directly applied to the preheated ore transfer pipe, the preheated ore transfer pipe is required to have excellent gas sealing properties.

At this time, it is also conceivable to powder-seal the preheated ore transfer pipe with fine ore flowing down the preheated ore transfer pipe toward the fluidized bed pre-reduction furnace. However, when simply powder-sealing a preheated ore transfer tube, the transfer tube is required to be quite long in order to obtain the powder pressure necessary for sealing.

Therefore, in the present invention, a pressure equalization header is provided in the middle of the preheated ore transfer pipe, and the internal pressure of the pressure equalization header is released into the fluidized bed pre-reduction furnace, thereby reducing the pressure necessary for sealing by 4.
This also prevents the preheating ore transfer pipe from becoming excessively long.

〔Example〕

Hereinafter, the features of the present invention will be specifically explained with reference to Examples.

FIG. 1 schematically shows the connection relationship between the ore preheating furnace and the fluidized bed prereduction furnace in this embodiment.

In this example, a fluidized bed preheating furnace 3 is employed as the ore preheating furnace. This fluidized bed preheating furnace 3 is charged with iron ore, limestone, and other raw materials for iron making, and coal. Fluidized bed preheating furnace 3
Coal is combusted in the furnace, and raw materials for iron making such as iron ore 9 and limestone are heated by this combustion heat, and the preheated ore mixed with coal, char, etc. is transferred to the fluidized bed pre-reduction furnace 6 .

The fluidized bed pre-reduction furnace 6 employs a pressurized fluidized bed in order to fluidize the fine ore having a large specific gravity and increase the reactivity. Therefore, the internal pressure of the fluidized bed pre-reducing furnace 6 is maintained at a value higher than the internal pressure of the fluidized bed preheating furnace 3 by several kg/cd. Therefore, this pressure difference is applied to the preheated ore transfer pipe 24 that connects the fluidized bed preheating furnace 3 and the fluidized bed prereduction furnace 6. At this time, if the gas sealing property of the preheated ore transfer pipe 24 is poor, the ore transfer ability of the preheated ore transfer pipe 24 will be reduced, and the reducing gas will leak from the preheated ore transfer pipe 24, resulting in a reduction in the efficiency of use of the reducing gas. do.

Therefore, the preheated ore transfer pipe 24 is required to have excellent gas sealing properties.

Therefore, in this example, a pressure equalizing header 25 is provided in the middle of the preheated ore transfer pipe 24, and the pressure equalizing header 25 and the freeboard of the fluidized bed pre-reducing furnace 6 are connected by a pressure guiding pipe 26.

Inside the pressure equalizing header 25, as shown in detail in FIG. 2, powder a remains at a predetermined angle of repose.

That is, a space 27 is formed between the powder a and the inner wall of the pressure equalizing header 25. Therefore, the reducing gas 11 rising inside the lower preheated ore transfer pipe 24b flows into the pressure equalizing header 25 and is collected in the space 27. However, since the impulse pipe 26 opens into this space 27,
The reducing gas 11 collected in the space 27 is returned to the free board above the fluidized bed pre-reduction furnace 6 via the pressure conduit 26, and is reused for reducing iron ore in the fluidized bed (R reduction furnace 6).

On the other hand, the pressure required for powder sealing is thus released from the pressure equalization ladder 25 to the fluidized bed pre-reduction furnace 6 via the impulse pipe 26, so the preheated ore transfer above the pressure equalization header 25 It does not join the pipe 24a. Therefore, gas sealing from the preheating ore transfer pipe 24b to the pressure equalization ladder 25 is completely performed, and the flow characteristics within the fluidized bed preheating furnace 3 are not adversely affected.

In addition to the pressure equalizing header used here, in addition to the one in which the diameters of the upper and lower preheated ore transfer pipes 24a and 24b are changed as shown in FIG. In other words, FIG.
This is an example in which the pressure impulse pipe 26 is opened into the space 27 created in the preheated ore transfer pipe 24 by 8. Figure fb) shows its internal state.

Further, in FIG. 1, a pneumatic feeder 29 is employed as a fine ore carrying device for feeding fine ore in the external circulation path into the fluidized bed preliminary reduction furnace 6. However, this fine ore carrying device is not limited to the pneumatic feeder, and for example, a rock feeder 30 as shown in FIG. 4 can also be adopted.

〔Effect of the invention〕

As explained above, in the present invention, a pressure equalization header is provided in the middle of the preheated ore transfer pipe that connects the fluidized bed preheating furnace and the fluidized bed prereduction furnace. This allows the pressure required for sealing to be maintained in the downcomer pipe below the pressure equalizing header, without transmitting that pressure to the downcomer pipe above the pressure equalizing header. Therefore, even if the pressure required for sealing is increased, the fluid state in the fluidized bed preheating furnace is not adversely affected, and the preheated ore transfer pipe can be shortened. Furthermore, since the reducing gas sent into the preheated ore transfer pipe at high pressure is sent into the fluidized bed pre-reduction furnace via the impulse pipe, it is possible to increase the utilization rate of the reducing gas while preventing leakage to the outside of the system. I can do it.

[Brief explanation of drawings]

Fig. 1 shows an outline of the connection relationship between the ore preheating furnace and the fluidized bed pre-reduction furnace in the embodiment of the present invention, Fig. 2 shows details of the pressure equalizing header arranged at the connection part, and Fig. 3 Another example of the pressure equalizing header is shown, and FIG. 4 shows another example of a fine ore carrying device. Moreover, FIG. 5 shows the flow of the melting reduction method previously developed by the present inventors.

Claims (1)

[Claims] 1. In a pre-reduction facility consisting of an ore preheating furnace and a fluidized bed pre-reduction furnace, a pressure equalizing header is provided in the middle of a preheated ore transfer pipe that connects the lower part of the ore preheating furnace and the fluidized bed pre-reduction furnace. A preheated ore transfer device to a fluidized bed pre-reduction furnace, characterized in that the pressure equalization header is connected to the inside of the fluidized bed pre-reduction furnace via a pressure conduit.