JP3465295B2 - Operation method and specification setting method of coke packed bed type smelting reduction furnace - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operating method and specification setting method for a two-stage tuyere type coke packed bed smelting reduction furnace.

[0002]

2. Description of the Related Art FIG. 4 shows a two-stage tuyere type coke packed bed smelting reduction furnace. The coke 1 is supplied from the upper hopper, hot air is blown from the annular pipe (hot air pipe) 3 through the upper tuyeres 5 and the lower tuyeres 6, and the powder raw material is fed from the powder raw material blowing lance 4 to be melted and reduced. . The exhaust gas 2 is discharged from the rising pipe, and the hot metal and slag 8 are discharged to the tap pipe 9 through the tap hole 7. Raceways 11 and 12 which are coke combustion regions are formed in front of the upper tuyeres 5 and the lower tuyeres 6.

Japanese Unexamined Patent Publication (Kokai) No. 58-204110 discloses a technique relating to the height of the upper tuyeres and the lower tuyeres, and found the conditions for forming a stable coke packed layer between the upper and lower tuyeres. It is a thing. However, heretofore, the mutual gap size between the two-way tuyere raceways has not been studied at all, and there is no device or literature.

[0004]

DISCLOSURE OF THE INVENTION The present invention is a device for preventing a raceway formed in front of a plurality of tuyere provided in the circumferential direction from interfering with an adjacent raceway. The raceway formed in front of the upper tuyeres burns while the coke swirls due to the hot air blown from the tuyeres.
In the coke packed bed type smelting reduction furnace, since a powdery metal oxide that is melted and reduced together with hot air is blown into this raceway, it is important that each raceway for each tuyere exists independently, and the present invention is , It aims at providing the technology regarding the operating method and apparatus therefor.

[0005]

According to the present invention, the operation of a coke packed bed type smelting reduction furnace having a plurality of tuyere, one set of upper and lower two stages, in the circumferential direction of the lower part of the furnace is carried out, Depending on the equipment conditions such as the number of tuyeres and the inner diameter of the tuyere, it is arranged in the circumferential direction.
The upper gap of the upper tuyeres was 300.
The method for operating a coke packed bed smelting reduction furnace is characterized by selecting the tuyere blowing gas flow rate and the coke diameter so as to be not less than mm, and operating under these operating conditions.

A second aspect of the present invention is a coke-filled bed type smelting reduction furnace having a plurality of tuyeres, each of which is a set of two upper and lower stages, arranged in the circumferential direction of the lower part of the furnace. Depending on the operating conditions such as the coke grain size used, it is arranged in the circumferential direction.
The specification setting method of the coke packed bed type smelting reduction furnace is characterized in that the diameter of the hearth and the number of tuyere are determined so that the clearance dimension of the raceway of the upper tuyeres is 300 mm or more. .

A third aspect of the present invention is to arrange the elements in a circumferential direction.
The method for operating a coke packed bed type smelting reduction furnace is characterized in that the coke particle size is selected so that the mutual gap dimension of the upper raceway is 12 times or more of the average particle size of the charged coke .

[0008]

In order to carry out the present invention, it is first necessary to grasp the size of the raceway. It is well known that the size of the raceway is determined by the following formula (1) depending on the amount of hot air blown from the tuyere, the tuyere inner diameter, and the like.

D _R = 8.81 × 10 ⁻³ × U · D _H / √ (D _p ) ... (1) U: Velocity (m / s) of hot air blown from the tuyere D _H : Tuyere inside diameter (m) D _P: average diameter of the coke to be filled (m) D _R: Raceway depth (m) the present inventors furnace the Kanabo from tuyeres during operation of the coke packed layer type smelting reduction furnace And the distance to the hard coke layer corresponding to the wall of the raceway was actually measured, and it was confirmed that it was in good agreement with the value obtained by the above-mentioned equation (1). At the same time, the width of the raceway was (2 ) Found that it can be obtained by the formula.

D _W = 0.75D _R (m) (2) D _W : Raceway width (m) As a result of repeating these measurement tests, smelting reduction is stably performed using a coke packed bed. In order to find out, the following critical conditions must be met. In other words, the condition that a raceway group formed by a plurality of tuyere arranged in the circumferential direction should have is that each raceway must function as a high-temperature reaction vessel surrounded by red hot coke. If there is too little space between the adjacent tuyere raceways, the raceways will interfere with each other. This means that a part of the reaction container is broken, and the raw material powder blown into the reaction container is in the same state as when it leaked out of the container, and the smelting reduction reaction cannot be performed stably.

In a more extreme case, the coke wall between the raceways collapses and the adjacent raceways are merged into one, so the air flow rate for each tuyere fluctuates significantly, and the entire furnace is changed. The pressure loss of fluctuates, and the stability deteriorates significantly. As a result of systematically conducting experiments, the present inventors found that in order for adjacent raceways to function independently of each other, the size of the raceway obtained by the above equations (1) and (2) should be satisfied. It has been found that the mutual gap dimension (L) of the raceway is required to be 300 mm or more.

Further, it has been found that this value also changes depending on the particle size of the coke charged. It has been found that even when the mutual gap dimension (L) is less than 300 mm, stable operation can be performed if the coke particle diameter is 12 times or more. Mutual gap size L of the raceway, said depending on the operational conditions (1), (2) determine the D _R, D _W by equation 1 elliptical to each major axis and minor axis D _R, D _W and It can be geometrically obtained by drawing like ~ 3.

As an index for evaluating the stability of operation, the content (%) of MnO in the slag discharged from the smelting reduction furnace
The experimental results are summarized as shown in FIGS. 5 and 6 using the reciprocal of FIG. 5 shows the relationship between the mutual gap dimension L of the raceways and (1 / MnO%).
%) Area of 0.9 or less is recognized as a poor stability area,
It is stable in a region where the mutual gap dimension L of the raceways is 300 mm or more. FIG. 6 shows the ratio (L / Dp) of the mutual gap size L of the raceways and the average particle size Dp of the coke (1 / MnO).
%), It became clear that there exists a minimum raceway gap size corresponding to the coke grain size. This means that the raceway gap size L is 30
When the operating condition is less than 0 mm, there is an advantage that stable operation can be performed using this coke condition.

[0014]

1 to 3 are cross-sectional views of the two-stage tuyere type coke packed bed type smelting reduction furnace shown in FIG. Figure 1
3 to 3 respectively show examples of three arrangements in the cross-sectional view (cross-sectional view taken along the line AA in FIG. 4) at the upper tuyere level. The depth D _{R of the} raceway and its width D _W are calculated by the formula (1),
It is obtained in (2). The horizontal cross-sectional shape of the raceway is approximately elliptical. The reason why there is a minimum value in the mutual gap dimension L is summarized below. The minimum value of L is the minimum gap for maintaining the independence of each of the upper tuyere raceways. The walls of the coke between the raceways must be self-sustaining against the impact of the swirling coke and the wind from both raceways. Experiments have found that the minimum thickness of the wall also depends on the coke particle size, and that a gap of 300 mm or more or 12 times the coke average particle or more is sufficient.

Table 1 shows the results of an operation test in which the amount of air blown (total hot air blown from each tuyere) was the same under the three experimental conditions shown in FIGS. Under the operating condition 1 (FIG. 1) of the raceway mutual gap L = 100 mm, MnO in the slag is 5 to 50 compared with the operating condition 2 (FIG. 2, L = 300 mm) and the operating condition 3 (FIG. 3, L = 500 mm). Many times. That is, it indicates that the reduction yield of Mn is poor and the operation of the furnace is unstable under the operating condition 1 as compared with the operating conditions 2 and 3.

Table 2 shows operation tests conducted for comparison.
Operating conditions 4 to 7 are shown. In operating condition 4, the diameter of the furnace under operating condition 1 was increased from 4 m to 4.2 m, and the raceway mutual gap L was 300 mm, so the operation was stable. As for operating condition 5, the operating condition of operating condition 4 was changed to reduce the average coke particle size from 22 mm to 20 mm. As a result, even with the same air flow as operating condition 4, the raceway increased and the raceway mutual gap decreased to 230 mm. Became unstable.

The operating condition 6 is a test result in which the diameter of the furnace is further increased to 4.3 m in order to improve the operating condition 5, and the raceway mutual gap is determined by the coke average particle diameter (2
The operation was stable at 250 mm, which is 12 times more than 0 mm). Operating condition 7 is the result of the test in which the amount of air blown was increased and the raceway was enlarged in the conditions of operating condition 2. As expected, the raceway mutual gap was too small and the operation became unstable.

In operating condition 8, the chorus average particle size was further reduced to 18 mm in order to improve operating condition 5, and as a result, the raceway gap was reduced to 220 mm, but it was more than 12 times the coke average particle size (18 mm). The operation was stable.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

EFFECT OF THE INVENTION In the two-stage tuyere type coke packed bed smelting reduction furnace, it was found that the mutual gap dimension (L) between raceways has the minimum value. When the value is smaller than the value (L = 300 mm), the operation is not stable and the reduction yield of metal is poor. For example, MnO is discharged as slag in an unreduced state.
The number of n minutes increases by 5 to 50 times. This value (L = 300
mm) (operating condition 3, L = 500 mm)
Operation is stable, and the reduction yield of metal is (operating condition 2,
(L = 300 mm), but the size of the raceway was small, so the amount of raw material blown in could only be less than in operating condition 2.

There is an optimum value for the gap size between raceways, and if it is smaller than this value, the stability of the raceway is lost and the reduction yield of metal deteriorates. On the contrary, if it is too large, productivity deteriorates. In other words, by optimizing the gap size between the raceways in accordance with the coke grain size and the air flow rate, not only the reduction yield of metal can be maximized, but also the productivity can be maximized.

[Brief description of drawings]

FIG. 1 is a sectional view of a raceway of a coke packed bed type smelting reduction furnace.

FIG. 2 is a sectional view of a raceway of a coke packed bed type smelting reduction furnace.

FIG. 3 is a sectional view of a raceway of a coke packed bed type smelting reduction furnace.

FIG. 4 is a vertical sectional view of a coke packed bed smelting reduction furnace.

FIG. 5 is a graph showing the relationship between the mutual gap dimension of raceways and MnO%.

FIG. 6 is a graph showing the relationship between (raceway gap size) / (coke average particle size) and MnO%.

[Explanation of symbols]

1 Coke 2 Exhaust gas 3 Annular tube (hot air tube) 4 Powder material injection lance 5 Upper stage tuyeres 6 Lower stage tuyeres 7 Iron tap hole 8 Hot metal / slag 9 Hot tap gutter

Continuation of front page (56) Reference JP-A-63-128108 (JP, A) JP-A-6-128617 (JP, A) JP-A-6-65621 (JP, A) JP-A-63-311080 (JP , A) Japanese Unexamined Patent Publication No. 5-302107 (JP, A) Actual Development No. 5-54527 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) C21B 11/02

Claims (3)

(57) [Claims] To 1. A furnace bottom of the furnace circumferential direction, hit the operation of the coke packed layer type smelting reduction furnace provided with a plurality of tuyeres of a set of two upper and lower stages, upper tuyere arranged in the circumferential direction Coke packed bed type characterized by selecting the upper stage tuyere blowing gas flow velocity and coke diameter according to the equipment conditions such that the mutual gap dimension of the raceway is 300 mm or more, and operating under these operating conditions Operation method of smelting reduction furnace. 2. In a coke packed bed type smelting reduction furnace having a plurality of tuyeres, one set of upper and lower two stages, provided in the circumferential direction of the lower part of the furnace, the race of the upper stage tuyere arranged in the circumferential direction. The diameter of the hearth and the top of the way should be 300mm or more
A method for setting specifications of a coke packed bed smelting reduction furnace, characterized in that the number of stage tuyeres is determined according to operating conditions . 3. A coke filling method, characterized in that the coke grain size is selected so that the mutual gap size of the upper raceways arranged in the circumferential direction is 12 times or more the average grain size of the charged coke. Operation method of layered smelting reduction furnace.