JP3439059B2 - Reduced iron production equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing reduced iron, in which a target object made of iron ore powder containing coal is placed on a circular type rotary hearth and the target object is reduced in a high temperature atmosphere. .

[0002]

2. Description of the Related Art An example of a conventional reduced iron manufacturing apparatus is shown in FIGS.
Shown in. 5 is a conceptual diagram of the reduced iron manufacturing apparatus, FIG. 6 is a schematic plan view of the reduced iron manufacturing apparatus, and FIG. 7 is a sectional view taken along the line VII-VII of FIG.

As shown in the figure, an annular rotary hearth 2 is rotatably arranged in a furnace wall 6 of a circular reduction furnace 1, and an object 10 is placed on the rotary hearth 2. The object 10 to be processed is heated and reduced. That is, drive wheels 5 are arranged below the rotary hearth 2 and the rotary hearth 2 is supported by the drive wheels 5 via rails 4. The rotary hearth 2 is driven by the drive wheels 5 as shown in FIG. Turn in the direction of the dotted arrow at a slow speed of 2-10 rph.

A charging port 11 is provided in the upper part of the reduction furnace 1, and the pellet-shaped object to be processed 10 charged from the charging port 11 is formed in a plurality of layers (1 to 3) on the rotary hearth 2 in the furnace wall 6. layer)
Be spread over. The object 10 to be treated has a diameter of 10 or less obtained by adding coal to powdery or granular iron ore and mixing it with a binder.
The pellets are hardened into pellets of about 20 mm and dried in advance by a dryer 12 provided separately.

A plurality of combustion burners 3 are attached to the inner peripheral surface of the furnace wall 6 of the reduction furnace 1, and the radiant heat of the high-temperature gas generated by the combustion burners 3 heats the object to be treated 10 to cause a reduction reaction. A sealing device 7 for high temperature gas is provided on the side wall of the rotary hearth 2. Further, an ejector 8 is provided at a certain location of the reducing furnace 1, and the object 10 to be subjected to the reduction reaction is ejected from the ejector 8 after about one rotation.

In the reduced iron manufacturing apparatus as described above,
After the object to be processed 10 is dried by the dryer 12 separately installed, the object to be processed 1 is placed on the rotary hearth 2 by continuously charging the dried object 10 from the charging port 11.
Since 0 is slowly swirled and the temperature is raised until it is heated and reduced, the thermal energy for drying the object 10 and the thermal energy for raising the temperature are separately required, and the thermal efficiency is not good. .

[0007]

The conventional reduced iron manufacturing apparatus as described above has the following problems. (1) When the reduction furnace 1 is a single-stage hearth, the dryer 12
However, since it is installed separately from the reduction furnace 1, heat energy for the dryer is required. (2) When the dryer 12 is installed independently of the reduction furnace 1, the object to be processed 10 that has been dried and preheated by the dryer 12
Since it is cooled while passing through the transport path, it is necessary to raise the temperature after it has been charged into the reduction furnace 1, and this thermal energy has been lost.

The present invention solves the problems in the conventional reduced iron production apparatus and constructs the inside of the reduction furnace into the upper and lower stages, so that the heating exhaust gas in the lower stage is guided to the upper stage and utilized for drying and preheating. It is an object of the present invention to provide a reduced iron manufacturing apparatus which is compact as a whole and has good thermal efficiency.

[0009]

In order to achieve this object, in the present invention, an object to be treated made of iron ore powder containing coal is placed on a rotary hearth that swirls in a circular reduction furnace. In a reduced iron manufacturing apparatus for heating and reducing an object to be processed in a high temperature atmosphere to obtain iron, the rotary hearths are constructed by stacking the upper and lower rotary hearths in two stages, and the upper rotary hearths are smaller than the lower rotary hearths. It is rotated at a high speed in a shape, and the upper rotary hearth is provided with an inlet for introducing the object to be processed and a transfer means for transferring the object to the lower rotary hearth, and the lower rotary hearth is provided with the object to be processed. An object to be processed on the upper rotary hearth is provided by providing a discharger for discharging outside and a combustion device for heating the object to be processed, and introducing the combustion gas generated in the lower rotary hearth to the upper rotary hearth. Is dried.

Further, a radiant heat conversion body of a porous material or a combustion catalyst body obtained by coating a catalyst on the radiant heat conversion body is interposed in a combustion gas flow passage for guiding combustion gas from a lower rotary hearth to an upper rotary hearth. It is also characterized.

[Operation] According to the reduced iron manufacturing apparatus of the present invention, the rotary hearths that swirl in the circular reduction furnace are configured by stacking the upper and lower two stages. When charged into the small-sized rotary hearth from the charging port, the rotary hearth on which the object to be processed is swirled at a high speed is dried and preheated by the heating gas, and is conveyed from the position where it is rotated about once to the lower stage.

Next, the object to be treated on the rotary hearth, which has been conveyed to the lower stage, receives radiant heat in a high-temperature gas atmosphere while slowly rotating at a low speed to complete the reduction reaction, and then is conveyed from a position where it has rotated approximately once. The object to be processed is discharged to the outside of the system by the machine. Further, the object to be treated in the lower stage is heated by the radiant heat of the high temperature gas from the combustion device provided in the lower stage to cause a reduction reaction. Then, the high-temperature exhaust gas used and exhausted in the lower stage is introduced from the lower stage to the upper stage, and by drying and preheating the object to be treated in the upper stage, the thermal energy can be effectively utilized and the thermal efficiency can be improved.

Further, since the radiant heat converter of the porous material or the combustion catalyst is interposed in the combustion gas passage for guiding the combustion gas from the lower rotary hearth to the upper rotary hearth, the combustible components exhausted from the lower rotary hearth are disposed. The high-temperature gas having the above-mentioned properties can be converted into radiant heat or burned by passing through the radiant heat converter or the combustion catalyst, and heat energy can be efficiently supplied to the object to be processed.

[0014]

DETAILED DESCRIPTION OF THE INVENTION

[Structure] An embodiment of the present invention will be described with reference to FIGS. 1 is a vertical cross-sectional view of the reduced iron manufacturing apparatus, FIG. 2 is a plan view of FIG. 1, FIG. 3 is an operation explanatory view of the reduced iron manufacturing apparatus, and FIG.
FIG. The same parts as those in the conventional example shown in FIGS.

In the reduced iron producing apparatus of this embodiment, the conventional dryer 12 is abolished, the rotary hearth (grade) in the reduction furnace is composed of two upper and lower stages, and the upper grade 22 is used for drying and preheating. It is configured by stacking a small-sized upper stage hearth 31 and a large-sized lower stage hearth 32 that heats and reduces with a lower stage grade 24. The high temperature combustion gas from the combustion burner 3 provided in the lower stage hearth 32 is used to process the object. 10 is used for heating and reduction reactions, and its high temperature exhaust gas is introduced into the upper stage hearth 31 so that it can be used for drying and preheating.

The object 10 to be used in this embodiment is, for example, powdery or granular iron ore to which coal is added, mixed with a binder, and solidified into pellets having a diameter of 10 to 20 mm. is there. As shown in FIGS. 1-2, the upper grade 22 is rotatably arranged in the upper hearth 31 of the reduction furnace 20, and the object 10 to be processed is placed on the upper hearth 31 so that the upper grade 22 can swirl at a high speed. ing.

That is, a supporting member 25 is attached to the lower portion of the upper grade 22, and turning rails 4 are rotatably fixed to both ends of the supporting member 25, while below the rail 4. Drive wheels 5 are arranged, and the rails 4 can ride on the drive wheels 5 and turn. The upper grade 22 is a rotary hearth having a continuous divided pan, is formed of a perforated plate or a wire mesh, and is capable of passing combustion gas. Each of the divided trays can be tilted by rotating the support member 25. The upper grade 22 is
As will be described later, it is located above the combustion burner 3, and the object 10 to be processed can be dried and preheated by the high-temperature exhaust gas introduced from the combustion burner 3.

On the ceiling of the upper hearth 31, the object to be processed 10 is placed.
And an exhaust duct 9 are provided. A floor plate 23 is disposed below the upper hearth 31, and an introduction hole 2 for guiding the heating gas from below is provided in the floor plate 23.
Many 7 are provided. Into the introduction hole 27, a radiant heat converter made of a mesh-like or honeycomb-like porous material or a combustion catalyst body obtained by coating the radiant heat converter with a catalyst such as platinum is interposed.

In the present embodiment, the radiant heat converter or the combustion catalyst is provided in the introduction hole 27, which is a combustion gas flow path, but the invention is not limited to this. A passage may be formed, or a radiant heat converter made of a porous material may be attached to the surface of the passage. The floor plate 23 of the upper grade 22 is partially inclined and is formed as a descending chute 26 that conveys the object 10 to the lower grade 24.

The lower grade 24 is rotatably arranged in the lower hearth 32 of the reduction furnace 20 and the lower grade 2 is used.
An object to be processed 10 is placed on the rail 4, a rail 4 is installed under the lower grade 24, and drive wheels 5 are arranged below the rail 4. Therefore, the rail 4 is attached to the drive wheel 5.
The lower grade 24 can turn in the lower hearth 32 at a low and slow speed. Combustion burners 3 are installed at a plurality of locations on the furnace wall of the lower stage hearth 32, and an exhauster 8 is provided at the lower stage grade 24, and the object 10 to which the reduction reaction is completed is passed through a hopper 28 outside the apparatus to the next stage. It is designed to be discharged into the process.

Therefore, the high temperature gas from the combustion burner 3 provided on the side wall of the lower stage hearth 32 is used for heating and reduction reaction in the lower stage grade 24 rotating at a low speed and then introduced into the upper stage grade 22 rotating in a high speed. Then, the object 10 to be processed is dried and preheated, sucked from the upper part of the upper hearth 31 to the exhaust duct 9, and discharged to the outside of the system.

FIG. 4 shows the condition of the object to be processed 10 placed on the upper grade 22 and the lower grade 24 and heated.
As shown in FIG.
Are arranged in almost one layer so that the radiant heat from the combustion burner 3 is sufficiently transmitted, the objects 10 to be treated are arranged in multiple layers on the upper grade 22, and the exhaust gas from below is introduced into the floor plate 23. After passing through 27, the upper grade 22 object 10 to be processed is dried and preheated.

Experimental Example The experimental conditions are shown below. Two-stage circular grade; upper grade diameter D = 10 m, width W = 1.2 m Lower grade diameter D = 50 m, width W = 5 m Grade rotation speed; upper stage 25 rph, lower stage 6.8 rph. Input speed of the object to be treated: 80 ton / h (reduced substance conversion). Object to be treated: A sphere with a diameter of 15 mm consisting of iron ore powder 77%, coal 18%, Ca (OH) ₂ 3.6% and binder 1.4%. Combustion burner: Multiple pulverized coal burning burners are installed on the lower side wall. Furnace atmosphere temperature: upper 300 ° C, lower 1300 ° C.

According to the experiment under these conditions, the object to be treated, which was charged from the charging port in the upper stage, was dried and preheated in the upper stage,
When the product was heated and reduced in the lower stage and then discharged, it was taken out as pellets with a reduction rate of 90% or more, and it was confirmed that this is a highly economical reduced iron production apparatus.

[Operation / Effect] According to the reduced iron manufacturing apparatus as described above, the small-sized upper stage hearth 31 and the large-sized lower stage hearth 32 are configured by being stacked in two upper and lower stages. The object 10 to be processed is the upper hearth 31
When it is thrown into the upper grade 22 from the charging port 21 of
The upper grade 22 on which the object 10 is placed is, for example, 20
The object to be processed 10 is dried by the heated exhaust gas rising from the lower stage while turning at a high speed of ˜30 rph, and when it reaches a position where it is rotated about once, it slides down due to the inclination of the divided pan due to the rotation of the support member 25, and the descending shoot It is conveyed from 26 to the lower grade 24.

Then, the object 1 to be processed on the lower grade 24
0 is a high temperature gas (for example, 1300 ° C.) from the combustion burner 3 while slowly turning at a low speed of 2 to 10 rph.
After being heated by receiving the radiant heat from the sheet and causing a reduction reaction, the sheet is discharged by the carry-out machine 8 from a position where it is rotated approximately once. Further, the heated exhaust gas, which is used in the lower stage hearth 32 and then guided to the upper stage, rises to the upper stage from the exhaust gas introduction hole 27 provided in the floor plate 23, and as shown in FIG. By preheating, the thermal energy is effectively used and the thermal efficiency is increased.

Further, since the radiant heat converter or the combustion catalyst which is a porous material is interposed in the introduction hole 27, the radiant heat conversion or combustion is carried out by the passage of the high temperature gas having the combustible component rising from the lower stage. The heat energy can be efficiently supplied to the object to be processed 10.

According to the apparatus for producing reduced iron as described above, the grades in the reduction furnace are arranged in upper and lower two stages, the upper stage is small and rotates at high speed, and the lower stage is large and rotates at low speed. The device is more compact than that of
The installation area can be reduced. Further, since the high-temperature exhaust gas in the lower stage is guided to the upper stage and used for drying and preheating, the exhaust loss of thermal energy is reduced and the thermal efficiency of the device is increased.

[0029]

As described above in detail with reference to the embodiments, according to the reduced iron manufacturing apparatus of the present invention, the iron ore powder containing coal is removed from the rotary hearth rotating in the circular reduction furnace. An apparatus for producing reduced iron, in which an object to be treated is placed, and the object is heated and reduced in a high-temperature atmosphere to obtain iron content, which is configured by stacking the rotary hearths in two upper and lower stages and The rotary hearth is rotated at a higher speed with a smaller shape than the lower rotary hearth, and the upper rotary hearth is provided with an inlet for introducing the object to be processed and a transport means for transporting the lower rotary hearth to the lower rotary hearth. The hearth is provided with a discharger for discharging the object to be processed and a combustion device for heating the object to be processed, and the combustion gas generated in the lower rotary hearth is introduced into the upper rotary hearth to allow the upper object Since the processing body is configured to dry, the device can be made compact. , Small heat loss or heat dissipation area by miniaturization of the upper is reduced, and the thermal energy of the hot exhaust gas generated in the lower, it is possible to increase the effective use heat efficiency drying and preheating at upper.

Further, in the combustion gas passage for introducing the combustion exhaust gas from the lower rotary hearth to the upper rotary hearth, a radiant heat converter made of a porous material or a combustion catalyst body obtained by coating the radiant heat converter with a catalyst is interposed. Since the high temperature gas having a combustible component exhausted from the lower stage passes through the radiant heat converter or the combustion catalyst, radiant heat conversion or combustion is performed, and heat energy is efficiently supplied to the object to be processed. You can As described above, according to the present invention, the entire apparatus becomes compact and heat energy can be used efficiently, so that it is possible to provide a reduced iron manufacturing apparatus with good economical efficiency.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a reduced iron manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is an operation explanatory view of the reduced iron manufacturing apparatus according to the embodiment of the present invention.

FIG. 4 is an explanatory view of a main part of FIG.

FIG. 5 is an explanatory diagram showing the concept of a conventional reduced iron manufacturing apparatus.

FIG. 6 is a schematic plan view of a conventional reduced iron manufacturing apparatus.

7 is a sectional view taken along the line VII-VII of FIG.

[Explanation of symbols]

3 combustion burner 4 rails 5 drive wheels 8 ejector 9 exhaust duct 10 Processing object 20 Reduction furnace 21 Input port 22 Upper grade 23 Floorboard 24 Lower grade 25 Support material 26 down shoot 27 introduction hole 31 Upper Hearth 32 Lower Haas

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP 10-204514 (JP, A) JP 1-152225 (JP, A) JP 47-4251 (JP, A) JP 58- 207307 (JP, A) JP 10-30106 (JP, A) JP 58-153088 (JP, A) JP 62-26487 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C21B 13/08 F27B 9/16 F27B 17/00 F27D 17/00 101

Claims (2)

(57) [Claims] 1. An object to be treated made of iron ore powder containing coal is placed on a rotary hearth rotating in a circular reduction furnace, and the object is heated and reduced in a high temperature atmosphere to obtain iron. In the reduced iron manufacturing apparatus, the rotary hearths are stacked in two layers, and the upper rotary hearth is rotated in a smaller shape and at a higher speed than the lower rotary hearth, and the upper rotary hearth has an object to be treated. A charging means for charging and a transporting means for transporting to the lower rotary hearth are provided, and further, in the lower rotary hearth, an ejector for discharging the object to be processed out of the furnace and a combustion device for heating the object to be processed. And a combustion gas generated in the lower rotary hearth to be introduced into the upper rotary hearth to dry the object to be processed on the upper rotary hearth. 2. A radiant heat converter of a porous material or a combustion catalyst body obtained by coating the radiant heat converter with a catalyst is provided in a combustion gas passage for introducing combustion gas from a lower rotary hearth to an upper rotary hearth. The reduced iron manufacturing apparatus according to claim 1, wherein