JPH05117727A - Method for manufacturing and supplying reduced ore into blast furnace - Google Patents

Abstract

PURPOSE:To reduce coke ratio and to improve ratio of consumption of steam coal and powdery ore by injecting the powdery ore reduced in fluidized bed reduction equipment in the separate system into the lower part of a blast furnace. CONSTITUTION:Powdery coal 19 and gas 24 for combustion are injected to the tangential direction from the side surface of a cylindrical reducing gas generating furnace 23 and circularly burnt to generate the high temp. reducing gas. This reducing gas is introduced into the fluidized bed reduction apparatus, and the powdery ore 16 introduced in this apparatus is fluidizing-reduced to produce the reduced ore 33. This fluidized bed reduction apparatus is formed with a riser 18 forming the fluidized bed and a down-comer 30 connecting the top part of the riser 18 with the lower part of the riser 18 through a solid-gas separator 29. Then the reduced ore 33 is injected into the blast furnace 15 through an injecting device 35 and further, reduced to obtain molten iron.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing and supplying reduced ore for supplying reduced ore to a blast furnace.

[0002]

2. Description of the Related Art In order to reduce iron ore to produce hot metal, a method of using a blast furnace is often adopted. The blast furnace uses a large amount of coke as a heat source and a reducing agent. Further, iron ore as an iron source is powdered ore sintered and charged into a blast furnace in order to maintain air permeability and reducing property in the furnace.

Therefore, the conventional blast furnace requires a large-scale facility such as a coke oven facility for carbonizing carbonized coal to produce coke and a sintering facility for sintering fine ore. Therefore, the blast furnace costs a lot of equipment. Moreover, it requires a limited amount of raw material resources, and the supply of strong coking coal is unstable because the amount of strong coking coal is small globally and the distribution is unevenly distributed locally. Further, in the case of iron ore, powdered ore has not been used in many cases because the processing cost is high.

However, due to the deterioration of the existing coke equipment, it is now necessary to rebuild the coke oven, and a technique for using a large amount of steam coal or powdered ore is being considered in view of the problem of coke reduction and raw material circumstances. For this reason, for the purpose of reducing the coke ratio and increasing the steam coal usage ratio to reduce the hot metal production cost, steam coal is pulverized and blown from the tuyere at the bottom of the blast furnace. As one of the methods, there is Japanese Patent Publication No. 51-29684, which is configured by the flow shown in FIG.

According to this method, it is possible to feed an equal amount of pulverized coal to a plurality of blowing tuyere of a blast furnace. This method will be briefly described with reference to FIG.

[0006] The pulverized coal finely pulverized in the fine pulverization equipment 1 is cut out and stored in a storage tank 3 via a valve 2. The valve 4A is opened to one of a plurality of supply tanks 5 (here, temporarily 5A) which repeats pressurization and depressurization periodically, and pulverized coal is supplied by its own weight. Next, the valve 4A is closed and high-pressure N ₂ gas is introduced into the supply tank to increase the pressure in the supply tank 5A according to the blast pressure of the blast furnace.

When the supply of the pulverized coal from the other supply tanks is completed, the valve 6A is opened to guide the pulverized coal to the distributor 7 with a pressing force. On the other hand, a high-pressure transfer gas is made to communicate with the distributor 7 through the valve 8, and the pulverized coal is transferred by the pneumatic tube 9 to the distributor 10 installed near the blast furnace.

Further, the gas is distributed to the tuyere 12 of the blast furnace 15 by the distributor 10 via the pneumatic tube 11. The pulverized coal is mixed with the hot air supplied through the hot air annular pipe 13 and the blower branch pipe 14 and burned. This method is aimed at reducing the coke ratio and improving the steam coal usage ratio.

[0009]

In such a pulverized coal blowing method, as the coke ratio is reduced, the reducing action to the ore and the sintered ore in the upper part of the blast furnace is reduced, and even up to the vicinity of the tuyere. However, the reduction is not completed, and an excessive reduction and dissolution capacity is required after the tuyere, which causes the operation of the blast furnace to be sluggish and reduces productivity. Therefore, the coke ratio reduction by blowing pulverized coal is naturally limited, and the amount of pulverized coal blowing is limited. Therefore, there is an upper limit for reducing the coke ratio and improving the steam coal usage ratio.

On the other hand, in order to improve the usage ratio of powdered ore, it is necessary to increase the sintering equipment, which requires a large amount of equipment cost, and in order to maintain a uniform gas flow in the blast furnace, the sintered ore is used. Due to reasons such as the inability to use a large amount, it has not been gradually improved.

With such a method, it is impossible to dramatically reduce the coke ratio, and it is not possible to expect a large improvement in the usage ratio of steam coal and powdered ore. Therefore, it cannot be expected that the situation of raw materials will improve due to the reduction of coke facilities and the expansion of use of steam coal and powdered ore, and the reduction of pig iron production cost cannot be obtained.

Therefore, the present invention efficiently reduces powdered ore using a fluidized bed reduction facility and blows the reduced ore together with pulverized coal near the tuyere, thereby significantly reducing the coke ratio and steaming coal. The purpose is to increase the use ratio of fine ore.

[0013]

The method for producing reduced ore of the present invention and supplying it to the vicinity of tuyere of a blast furnace is a method for producing reduced ore in a fluidized bed to produce pulverized coal and combustion gas.
A riser that forms a fluidized bed by blowing and combusting a tangential direction from the side of a cylindrical reducing gas generation furnace to form a high-temperature reducing gas, and the riser and the top of the riser and the lower part of the riser are a solid-gas separator. Introduced into a fluidized bed reducing device consisting of a downcomer connected via, to produce reduced ore by fluidizing and reducing the powdered ore charged in the fluidized bed reducing device, the reducing ore through a blowing device It is characterized by blowing into the bottom of the blast furnace.

[0014]

In the present invention, steam coal is crushed to a size of several mm or less and blown into a cylindrical swirl-type reducing gas generator together with oxygen-enriched air in a tangential direction away from the core. . This pulverized coal is burned while flowing in a cylindrical furnace inner wall while swirling to ash (slag), and at the same time it becomes a molten slag state due to high temperature and flows down the wall surface and is discharged to the outside of the furnace. It

On the other hand, the generated gas rises while swirling upward and is blown into the lower part of the fluidized bed (riser). This generated gas suppresses the supply air amount to about 20 to 80% of the theoretical oxygen amount, and burns coal in a reducing atmosphere to produce C
It is a reducing gas rich in reduction of iron ore containing O and H ₂ .

As described above, since most of the ash content in the coal is melted and slagged to be removed as described above, a clean reducing gas is obtained, the ash content of the low melting point in the reducing gas becomes small, and the conduit in the middle Less ash adheres to the surface, and adhesion problems can be avoided. The degree of reduction of the reducing gas can be adjusted by adjusting the amount of supply air.

The high-temperature reducing gas generated by this reducing gas generator is introduced into the lower part of the riser to fluidize and reduce the fine ore in the riser. Fine ore is continuously fed to the riser. A part of the fine ore flows upward while flowing in the riser.

Therefore, at the outlet of the fluidized bed, a dust collector such as a cyclone is attached to collect the particles, and an external circulation device (downcomer) for recirculating the particles in the furnace is attached to the riser to circulate and flow the powdered ore. It is devised so that the powdered ore is reduced almost uniformly.

By adjusting the concentration of the fine ore in the riser to control the required residence time of the fine ore to reach a predetermined average reduction rate, the reduced ore is discharged from the lower part of the riser.

This reduced ore is conveyed to a distributor arranged near the blast furnace, and is distributed to the tuyere of the blast furnace by the distributor.
Pulverized coal is also injected from the tuyere together with this reduced ore.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the present invention will be specifically described below with reference to the embodiment of FIG. The iron ore 16 is loaded into the riser 18 of the fluidized bed reducing apparatus via the hopper 17. Coal 19
Is pressurized by the combustion gas 22 in the blowing device 21 through the hopper 20, and is blown into the swirl combustion furnace 23. The combustion gas is oxygen-enriched air.

As shown in FIG. 2, coal and the combustion gas 24 are blown tangentially into the swirl combustion furnace and burned while forming a swirl flow in the furnace. Coal burns while being pressed against the wall by centrifugal force. The inside of the furnace is maintained at a high temperature of one thousand and several hundred degrees Celsius, and the ash content in the coal is melted into slag, flows down the wall surface, and is discharged from the lower part 25 of the furnace.

A high-temperature reducing gas is generated by supplying the oxygen in the combustion gas in an amount smaller than the amount for completely burning the coal to partially burn the coal and creating a reducing atmosphere in the furnace. The reducing gas rises while swirling in the swirling combustion furnace and is introduced into the reducing gas header 26 below the riser.

The riser is blown into the riser through a nozzle 27. The gas composition of this reducing gas is adjusted by the supply ratio of coal and the amount of combustion gas. Further, the combustion gas is an oxygen-enriched gas obtained by adding oxygen to air, and the oxygen enrichment rate is adjusted by the temperature and the degree of reduction of the reducing gas.

The iron ore charged in the riser is mixed with the iron ore in the riser and fluidized and reduced by the reducing gas supplied from the nozzle. The iron ore floats in the riser and is reduced by CO, H _{2 and the} like contained in the reducing gas. The flow velocity of the reducing gas in the riser is increased so that the iron ore floats and scatters in the riser. This improves the reduction reactivity.

Therefore, a part of the iron ore is scattered along with the gas above the riser. This scattered iron ore is gas-solid separated by a cyclone 29 connected to the riser outlet with a connecting pipe 28, and the iron ore descends a downcomer 30 below the cyclone, and an ore circulation adjuster 31 provided below the downcomer 30. Circulated under the riser.

Carrier gas 32 is blown into the ore circulation regulator to regulate the circulation amount of iron ore. On the other hand, the gas is discharged to the outside of the system through the exhaust pipe 36.

Then, the reduced iron ore is discharged from the lower part of the downcomer to the reduced ore distributor 33, and is distributed to the vicinity of the tuyere of the blast furnace. The reduced ore distributed near the tuyere is pressurized by the high-pressure carrier gas 34 and blown into the blast furnace through the nozzle 35. In this case, the reduced ore blowing nozzle is separated from the hot air and the tuyere that blows the pulverized coal, and they are separately supplied into the furnace of the blast furnace.

[0029]

According to the method for producing and supplying reduced ore to a blast furnace of the present invention, a reduced ore is efficiently produced by combining a swirling combustion furnace for coal, a fluidized bed reduction furnace and a system for supplying reduced ore to the blast furnace. , It becomes possible to supply to the blast furnace.

When the coal is partially burned at a temperature higher than the melting point of the coal ash by using a swirl combustion furnace, the ash content in the coal is melted and slagged to flow down the inner wall surface of the furnace, and is effectively removed. By using inexpensive steam coal, the production cost of the reducing gas is reduced.

Since the reducing gas is clean, it is possible to avoid troubles such as adhesion of ash in the reducing gas blowing portion to the fluidized bed reducing apparatus. Coal powder, which was not completely gasified in the process of producing reducing gas, vaporizes volatile components and turns into char,
It is blown into the riser by riding the reducing gas flow. This char acts as a reducing agent for iron ore in the riser, is discharged together with the reducing ore, is blown into the blast furnace, and is effectively used as a reducing agent in the blast furnace.

Therefore, the efficiency of reducing the iron ore of the reducing gas producing coal is high. Further, by directly injecting the high-temperature reduced ore, the thermal compensation near the tuyere of the blast furnace is reduced.

By blowing the reducing ore and the coal from the tuyere of the blast furnace in this way, the reducing load at the upper part of the blast furnace can be reduced, and it is expected that the coke ratio will be greatly reduced and a large amount of powdered ore will be used. As a result, the auxiliary equipment such as coke equipment and sintering equipment can be saved, and equipment costs, operating costs, etc. can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention.

FIG. 2 is a sectional view of a swirl combustion furnace of the present invention.

FIG. 3 is a schematic view of a conventional pulverized coal supply device for a blast furnace.

[Explanation of symbols]

 1 Coal fine crushing equipment 2 Cut-out valve 3 Tank 4 Cut-out valve 5 Tank 6 Cut-out valve 7 Distributor 8 Valve 9 Air tube 10 Distributor 11 Air tube 12 Tuyere 13 Hot air annular tube 14 Air blow pipe 15 Blast furnace 16 Iron ore 17 Hopper 18 Riser 19 Coal 20 Hopper 21 Blow-in device 22 Combustion gas 23 Swirling combustion furnace 24 Combustion gas 25 Lower swirling furnace bottom 26 Reducing gas header 27 Nozzle 28 Connecting pipe 29 Cyclone 30 Downcomer 31 Ore circulation regulator 32 Carrier gas 33 Reduction Ore Distributor 34 Carrier Gas 35 Nozzle 36 Exhaust Pipe

Claims (1)

[Claims] 1. A method for producing reduced ore and supplying it to a blast furnace, in which pulverized coal and a combustion gas are blown in a tangential direction from a side surface of a cylindrical reduction generation furnace to perform swirl combustion to generate high-temperature reducing gas, This gas is introduced into a fluidized bed reduction apparatus comprising a riser for forming a fluidized bed and a downcomer connecting the top and the lower portion of the riser through a solid-gas separator, and charged into the fluidized bed reduction apparatus. A method for producing and supplying reduced ore to a blast furnace, characterized in that the reduced ore thus produced is fluidized and reduced to produce reduced ore, and the high-temperature reduced ore is blown into the lower part of the blast furnace through a blowing device.