JPH11325740A - Grate kiln iron ore pellet firing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the occurrence of a material, such as the coal ash, etc., adhering to the internal wall of a preheating chamber and, at the same time, to raise the temperature in the preheating chamber in the optimum heating pattern, by arranging a plurality of burners on the facing longitudinal walls of the preheating chamber at prescribed intervals in the longitudinal direction as means for raising the temperature of the exhaust combustion gas of a rotary kiln. SOLUTION: As exhaust combustion gas temperature raising means which are provided for raising the temperature of the exhaust combustion gas of a rotary kiln 9, for example, three burners 21A which are used for burning fuel injected into a preheating chamber 5 together with the residual oxygen in the exhaust combustion gas in the kiln 9 are arranged in rows on the facing longitudinal walls of the chamber 5 closely to a continuous fire gate 2 along the longitudinal direction of the chamber 5. In addition, a wind box group 6 composed of a plurality of wind boxes is arranged in parallel with each other against the preheating chamber 5. The temperature of a gas for heating immediately below the fire grate 2 is maintained at a target value by detecting the temperature of the gas by means of a temperature sensor, and adjusting the opening of each damper of a suction fan 7 based on the output of the sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for firing iron ore pellets of a great kiln system in which raw pellets are fired to produce iron ore pellets as a raw material for a blast furnace.

[0002]

2. Description of the Related Art A sintering process for producing iron ore pellets includes drying, preheating, sintering, and cooling processes. As a firing device), a device as shown in a vertical sectional view of FIG. 8 is conventionally known. As shown in the figure, this great kiln type firing apparatus includes a traveling great furnace 1, a preheating chamber burner 8 as a kiln combustion waste gas heating means, a rotary kiln 9, and an annular cooler 11.

In the traveling great furnace 1, raw pellets GP laid on a pallet of the grate 2 by an endless continuous moving grate 2 are converted into a drying room 3, a water separation room 4, and a preheating room 5.
Are dried and preheated by downward ventilation of a heating gas, which will be described later, while moving in the longitudinal direction of each chamber in this order. The water separation chamber 4 is installed when the ore contains compound water.

[0004] Reference numeral 6 denotes a group of wind boxes for a preheating chamber. The space below the continuously moving grate 2 is partitioned into a plurality of rooms along the pellet moving direction, and these rooms are called wind boxes. In other words, the preheating chamber wind box group 6 is composed of a plurality of wind boxes. For example, nine wind boxes are arranged in a line with respect to the preheating chamber 5 along the longitudinal direction (pellet moving direction). ing. Reference numeral 7A denotes a suction fan for a preheating chamber, which has a fan damper (not shown) for adjusting a suction air flow rate (downward ventilation flow rate), and a high-temperature kiln combustion waste gas used for pellet firing from a rotary kiln 9 described later. Preheating chamber 5 as a heating gas
The heating gas is sucked downward through the pellet layer on the pallet of the grate 2 and the wind box group 6 and sent out into the next water separation chamber 4.

[0005] Each wind box has a structure that branches off on both sides with respect to the longitudinal axis (great furnace axis) of the preheating chamber 5 (see FIG. 3). The side part communicates with one preheating chamber suction fan 7A via an individual duct and an integration manifold, and in the same manner,
The other side communicates with the other preheating chamber suction fan 7B (not shown) through an individual duct and an integration manifold (see FIG. 2). And these suction fans 7A,
Fan dampers (not shown) are provided at positions immediately before 7B.

The rotary kiln 9 is directly connected to the great furnace 1 and is a cylindrical rotary furnace having a gradient. The rotary kiln 9 is provided with a preheating chamber of the great furnace 1 by combustion by a kiln burner 10 provided at an outlet side. While the dried and preheated pellets charged from Step 5 are fired, the high-temperature combustion waste gas used for firing the pellets is fed into the preheating chamber 5 as a heating gas. In this example, pulverized coal and coke oven gas are blown into the rotary kiln 9 by the kiln burner 10 and burned together with combustion air. Annular cooler 11 cools the fired pellets from rotary kiln 9 into cooling fan 1.
The high-temperature chamber 11a on the rotary kiln 9 side and the low-temperature chamber 11b on the side near the mining section are separated by the cool air from the rotary kiln 9, and the waste gas from the high-temperature chamber 11a is sent to the kiln 9 to recover heat. And soaking in the inclined kiln 9 in the longitudinal direction.

Further, the preheating chamber 5 is provided with a preheating chamber burner 8 as a kiln combustion waste gas heating means for raising the temperature of the kiln combustion waste gas from the rotary kiln 9. The preheating chamber burner 8 is provided at a center position in the preheating chamber width direction of the preheating chamber outlet wall 5c extending in the preheating chamber width direction perpendicular to the pellet moving direction, and includes a single burner that blows fuel into the preheating chamber 5. It becomes. In this example, coke oven gas is blown into the preheating chamber 5, and the coke oven gas is burned with residual oxygen in the kiln combustion waste gas.

In the great kiln type sintering apparatus constructed as described above, as described above, a single preheating chamber burner 8 is installed on the preheating chamber outlet wall 5c, and the pellet strength at the preheating chamber 5 outlet is set to a required value. In this case, the temperature of the kiln combustion waste gas from the kiln 9 is increased by blowing coke oven gas as fuel in the preheating chamber 5 with the burner 8 in this example. By doing so, the generation of kiln rings in the rotary kiln 9 (thing in which powdered pellets adhere to the brick wall of the kiln inner wall), which causes unstable operation, is prevented.

[0009]

However, in the conventional iron ore pellet baking apparatus described above, the preheating chamber burner 8 for raising the temperature of the kiln combustion waste gas is provided with the kiln combustion waste gas from the kiln 9 as shown in FIG. Is disposed so that the burner frame is positioned in the flow obliquely upward, so that a part of the burner frame of the burner 8 moves toward the ceiling of the preheating chamber 5. Ceiling wall and exit wall 5c
In addition, there is a problem that pellet fine powder or coal ash in pulverized coal fired by the kiln burner 10 is fused and adhered.
When this deposit grows, it falls off and the Great Furnace 1
Therefore, it is necessary to stop the apparatus and remove the deposits since the equipment may be caught by the outlet chute.

Another problem is that the temperature difference of the heating gas in the width direction of the preheating chamber is large, and the degree of preheating varies greatly. That is, in general, the filling state of the pellets to be preheated loaded on the continuously moving grate 2 or the grate 2
Due to the meandering state of the air conditioner, the amount of downward ventilation in the width direction of the preheating chamber 5 (width direction of the grate 2) is not uniform. By doing so, the temperature immediately below the continuously moving grate 2 is set to a constant target value. However, in the conventional apparatus, since the preheating chamber burner 8 is not a distributed heat source but a single point heat source disposed at one place, when the temperature of the kiln combustion waste gas is increased by the burner 8, a grate is used. The temperature difference in the width direction of the preheating chamber 5 just below 2 may be too large to the extent that it cannot be adjusted by the opening degree of the fan damper,
At this time, there is a problem that the temperature of the kiln combustion waste gas must be lowered to reduce the production amount. Further, the preheating chamber burner 8 has a problem that the relationship between the pellet residence time in the preheating chamber 5 and the pellet temperature (pellet heating pattern) cannot be sufficiently adjusted.

An object of the present invention is to feed raw pellets from a rotary kiln as a heating gas into a preheating chamber which is preheated by downward ventilation of a heating gas while moving the raw pellets in the longitudinal direction of the preheating chamber by a continuously moving grate. In a great kiln-type iron ore pellet baking apparatus equipped with a means for raising the temperature of kiln combustion waste gas, the preheating chamber is heated without generating any deposits such as coal ash due to overheating of the ceiling wall on the ceiling wall of the preheating chamber. Temperature to the required temperature,
In addition, it is possible to substantially eliminate the temperature difference of the heating gas in the preheating chamber width direction perpendicular to the pellet moving direction in the preheating chamber and realize an optimal heating pattern also in the preheating chamber longitudinal direction. An object of the present invention is to provide a stone pellet firing apparatus.

[0012]

In order to achieve the above object, a great kiln-type iron ore pellet firing apparatus according to the present invention is characterized in that raw pellets are continuously moved by a grate in the order of a drying chamber and a preheating chamber in the order of the length of each chamber. While moving in the direction, a traveling great furnace for drying and preheating by downward ventilation of the heating gas, and burning the dried and preheated pellets charged from the great furnace by burning with a kiln burner, while the pellets are fired. A rotary kiln for feeding the kiln combustion waste gas used for firing to the preheating chamber as the heating gas, and a rotary kiln provided in the preheating chamber of the great furnace for raising the temperature of the kiln combustion waste gas from the rotary kiln. Kiln combustion waste gas heating means, and an annular cooler for cooling the fired pellets from the rotary kiln In a great kiln-type iron ore pellet firing apparatus for firing raw pellets to produce iron ore pellets as a blast furnace charging raw material, the kiln combustion waste gas heating means is provided on each of opposed longitudinal walls of the preheating chamber, A plurality of burners for injecting fuel into the preheating chamber to burn residual oxygen in the kiln combustion waste gas are located in proximity to the continuously moving grate in the height direction of the longitudinal wall, and It is characterized by being arranged at predetermined intervals along the direction.

In the great kiln-type firing apparatus according to the present invention, as the kiln combustion waste gas heating means, fuel is blown into each of the opposed longitudinal walls of the preheating chamber to the kiln combustion waste gas. Preheating in which a plurality of burners to be burned with residual oxygen are located close to the continuously moving grate in the height direction of the longitudinal wall, and are arranged at predetermined intervals along the longitudinal direction of the preheating chamber. Since the preheating chamber burner row was positioned close to the continuously moving grate in the height direction of the longitudinal wall, the continuous heating grate was suctioned by the suction fan for the preheating chamber. The burner frame of the preheating chamber burner row is located in the flow of the incoming heating gas which is substantially vertically downward with respect to the grate, so that the coal ash caused by overheating of the preheating chamber ceiling wall or the like. Without hardly generate deposits, it can raise the temperature of the heating gas preheating chamber to the required temperature. In this case, the preheating chamber burner row is continuously arranged so that the distance h between the continuously moving grate in the height direction is equal to or less than half the height H of the preheating chamber (the distance between the continuously moving grate and the preheating chamber ceiling). It is desirable to be located close to the moving grate.

In addition, since the preheating chamber burner rows are provided on both longitudinal walls of the preheating chamber in opposition to each other with a pellet moving path (continuous moving grate) therebetween, the preheating chamber is perpendicular to the pellet moving direction. The temperature adjustment of the heating gas in the width direction is performed in addition to the adjustment of the opening degree of each fan damper of the preheating chamber suction fan disposed on both sides of the preheating chamber with the preheating chamber therebetween.
By adjusting the fuel injection amount of the two preheating chamber burner rows, this can be easily performed, and the temperature difference of the heating gas in the width direction of the preheating chamber can be substantially eliminated. Further, since the preheating chamber burner row is formed by arranging a plurality of burners at predetermined intervals along the longitudinal direction of the preheating chamber, by adjusting the fuel injection amount of each burner, in the longitudinal direction of the preheating chamber. Also, an optimum pellet heating pattern can be realized.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a great kiln type iron ore pellet firing apparatus according to an example of the present invention, FIG. 2 is a plan view showing a main part of the firing apparatus shown in FIG. 1, and FIG. FIG. Here, in this example, the structure is the same as that of the conventional apparatus shown in FIG. 8 except that the kiln combustion waste gas temperature raising means is different, and therefore the same parts are denoted by the same reference numerals as in FIG. Are omitted, and different points will be described.

As shown in FIG. 1 to FIG. 3, as a kiln combustion waste gas heating means for raising the temperature of the combustion waste gas from the rotary kiln 9, the preheating chamber 5 has two opposed longitudinal directions. In this example, three burners are used to inject fuel (in this example, coke oven gas) into the preheating chamber 5 to burn residual oxygen in the kiln combustion waste gas into the walls 5a and 5b, respectively. Preheating chamber burner rows 21A and 21B which are located in the height direction of the continuously moving grate 2 and are arranged in a line at predetermined intervals along the longitudinal direction of the preheating chamber 5 are provided. I have. Figure 2
As shown in FIG. 3, each burner of one burner row 21A and each burner of the other burner row 21B are provided so as to face each other with the continuously moving grate 2 therebetween.

In this embodiment, the preheating chamber 5 has an effective width W
Is 4.7 m, and the effective length L in the longitudinal direction is 27.45 m. And the grate 2 and the burner row 21 in the height direction
The distance h between the A and 21B is about 1/3 of the height H of the preheating chamber 5.
And A preheating chamber wind box group 6 including a total of nine wind boxes No. 12 to No. 20 is arranged in a line along the longitudinal direction of the preheating chamber 5 with respect to the preheating chamber 5.
As shown in FIG. 4, three burners constituting 1A are 12.2 m, 21.35 m, and 27.4 m from the preheating chamber 5 inlet.
Are arranged at the respective positions. The other burner row 21
The same applies to B.

In the great kiln type firing apparatus having such a configuration, the kiln combustion waste gas from the rotary kiln 9 is guided to the preheating chamber 5 of the great furnace 1 by the suction fans 7A and 7B, and the preheating chamber burner rows 21A and 21B. Temperature. The heated gas for heating is sucked downward by the suction fans 7A and 7B to heat the raw pellets on the continuously moving grate 2 to a required temperature. At this time, the amount of coke oven gas blown into the preheating chamber burner rows 21A and 21B is determined by the pellet strength at the outlet of the preheating chamber 5 and the temperature of the heating gas just below the continuously moving grate 2.

That is, the temperature of the heating gas immediately below the grate 2 is constantly detected by the temperature sensor, and is adjusted to the target value by adjusting the opening of each damper of the suction fans 7A and 7B. It is constantly being adjusted for this purpose. When the adjustment range based on the damper opening exceeds the range, the coke oven gas injection amount of the preheating chamber burner rows 21A and 21B is adjusted to adjust and control the temperature of the heating gas just below the grate 2. I have. When the pellet control at the outlet of the preheating chamber 5 actually measured by the batch method fluctuates from a predetermined value, the coke oven gas injection amount of the burner rows 21A and 21B is adjusted for the strength control. Is to be adjusted.

The preheating chamber burner rows 21A, 21
Great kiln type firing apparatus of the present invention having B,
For comparison, Table 1 shows the amount of fuel used so that the quality of the product is constant (the amount of heat contributing to firing is constant) in the conventional great kiln type firing device shown in FIG. The coke oven gas of a total of 6000 Nm ³ / h is blown into the preheating chamber burner rows 21A and 21B, and 50 is used in the conventional preheating chamber burner 8.
A coke oven gas of 00 Nm ³ / h was blown into the preheating chamber 5.
The temperature of the gas for heating just below the ceiling and the temperature of the gas for heating 1.2 m above the pellet layer on the grate 2 were measured.
The temperature measurement positions in the longitudinal direction of the preheating chamber 5 are positions corresponding to the wind box No. 12, the wind box No. 17, and the wind box No. 20.

[0021]

[Table 1]

FIG. 5A shows the measurement results of the apparatus of the present invention, and FIG. 5A shows the measurement results of the conventional apparatus (comparative example).
(B) of FIG. As can be seen from the results, according to the great kiln type firing apparatus of the present invention, the preheating chamber burner row 2
Since 1A and 21B are located close to the continuously moving grate in the height direction of the longitudinal walls 5a and 5b, the heating gas flowing toward the continuously moving grate 2 by suction by the preheating chamber suction fans 7A and 7B. The burner frames of the burner rows 21A and 21B are located in the flow almost vertically downward with respect to the grate 2 without overheating the ceiling wall of the preheating chamber 5 as compared with the conventional apparatus, that is, overheating the ceiling wall. Burner row 2 with almost no deposits such as coal ash
It was possible to heat the pellet by increasing the gas injection amount of the coke oven by 1A and 21B.

Next, the amount of coke oven gas blown into the preheating chamber 5 by the burner was varied in the great kiln type firing apparatus of the present invention and the conventional apparatus for comparison, and the continuously moving grate 2 was used. The temperature difference of the heating gas in the width direction of the preheating chamber immediately below was measured. FIG. 6 shows the results.

As can be seen from FIG. 6, according to the great kiln type sintering apparatus of the present invention, the temperature of the heating gas in the width direction of the preheating chamber is controlled by the preheating chambers arranged on both sides of the preheating chamber 5. In addition to adjusting the opening degree of each fan damper of the suction fans 7A, 7B, two preheating chamber burner rows 21A,
By adjusting the coke oven gas injection amount of 21B,
This was easily performed, and the temperature difference of the heating gas in the width direction of the preheating chamber could be extremely reduced to about 20 ° C. or less.

In the above-described great kiln-type firing apparatus of the present invention and the conventional apparatus for comparison, in both cases, a coke oven gas of 5000 Nm ³ / h was blown into the preheating chamber 5, and the grate in the preheating chamber 5 was used. The temperature in the pellet layer above 2 was measured, and the relationship between the pellet residence time in the preheating chamber 5 (longitudinal position in the preheating chamber) and the pellet temperature, that is, the pellet heating pattern was examined. FIG. 7 shows the results.

As can be seen from FIG. 7, according to the apparatus of the present invention, a plurality of preheating chamber burner rows 21A, 21B, in this example, three burners are arranged at predetermined intervals along the longitudinal direction of the preheating chamber. By adjusting the amount of fuel injected into each burner, the time required to reach the pellet temperature for obtaining pellets of the required strength at the outlet of the preheating chamber 5 can be shortened as compared with the conventional apparatus. Thus, an optimum pellet heating pattern can be realized. As shown in FIG. 7, for example, to reach 1000 ° C., the conventional apparatus requires up to the position of wind box 19, whereas the apparatus of the present invention obtains it at the position of wind box 17.

[0027]

As described above, according to the iron ore pellet firing apparatus of the present invention, the raw pellets are preheated by the downward ventilation of the heating gas while moving the raw pellets in the longitudinal direction of the preheating chamber by the continuously moving grate. In a great kiln-type iron ore pellet firing apparatus provided with a means for raising the temperature of kiln combustion waste gas sent from a rotary kiln as a heating gas to the preheating chamber to be heated, the kiln combustion waste gas heating means includes a preheating chamber A plurality of burners for blowing and burning fuel into the preheating chamber are positioned on the opposed longitudinal walls, respectively, in the height direction of the longitudinal walls, in the vicinity of the continuously moving grate, and in the longitudinal direction of the preheating chamber. Because it is arranged at a predetermined interval along
The heating gas in the preheating chamber can be heated to a required temperature without substantially generating deposits such as coal ash due to overheating of the ceiling wall in the preheating chamber ceiling wall, and preheating perpendicular to the pellet moving direction in the preheating chamber. The temperature difference of the heating gas in the chamber width direction can be substantially eliminated, and the optimum heating pattern can be realized also in the longitudinal direction of the preheating chamber.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a great kiln type iron ore pellet firing apparatus according to an example of the present invention.

FIG. 2 is a plan view showing a main part of the firing apparatus shown in FIG.

FIG. 3 is a transverse sectional view for explaining a preheating chamber in FIG. 2;

FIG. 4 is a view for explaining a row of preheating chamber burners arranged on a longitudinal wall of the preheating chamber.

FIG. 5 is a diagram showing a measurement result of a temperature of a heating gas in a preheating chamber.

FIG. 6 is a diagram showing a measurement result of a temperature difference of a heating gas in a width direction of a preheating chamber immediately below a continuously moving grate.

FIG. 7 is a diagram showing a measurement result of a pellet heating pattern in a preheating chamber.

FIG. 8 is a longitudinal sectional view showing a conventional great kiln type iron ore pellet firing apparatus.

[Explanation of symbols]

1 ... traveling great furnace 2 ... continuous moving grate 3
... drying room 4 ... water separation room 5 ... preheating room 5a, 5b ... preheating room longitudinal wall 5c ... preheating room outlet wall 6 ... preheating room wind box group 7A, 7B ... preheating room suction fan 8 ... preheating room burner 9 ... Rotary kiln 10 Kiln burner 11 Annular cooler 11a High temperature room 11b Low temperature room 1
2: Cooling fans 21A, 21B: Preheating chamber burner row

Claims (1)

[Claims] The raw pellets are dried by a continuously moving grate in a drying room.
While moving in the longitudinal direction of each chamber in the order of the preheating chamber, a traveling great furnace for drying and preheating by downward ventilation of the heating gas, and the drying and preheating loaded from the great furnace by burning by a kiln burner. A rotary kiln that feeds the kiln combustion waste gas used for firing the pellets to the preheating chamber as the heating gas while firing the pellets, and a kiln from the rotary kiln that is provided in the preheating chamber of the great furnace. A kiln for raising the temperature of the combustion waste gas, a heating device for raising the temperature of the combustion waste gas, and an annular cooler for cooling the fired pellets from the rotary kiln; In a great kiln-type iron ore pellet baking apparatus for producing stone pellets, the kiln combustion waste gas heating means comprises: A plurality of burners for blowing fuel into the preheating chamber and combusting residual oxygen in the kiln combustion waste gas on each of the opposed longitudinal walls of the preheating chamber, the continuously moving grate in the height direction of the longitudinal walls. A great kiln-type iron ore pellet firing apparatus characterized in that the iron ore pellet firing apparatus is positioned close to the preheating chamber and arranged at predetermined intervals along the longitudinal direction of the preheating chamber.