JPH0772286B2 - Topless charging method for bellless blast furnace - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for charging a furnace top of a bellless blast furnace, which reduces distribution deviation of furnace interior charges in the furnace circumferential direction, and particularly to charging of raw materials. It relates to a method for charging the top of a bellless blast furnace in which coke and ore are charged in layers by changing the charging positions and types by 3 or more.

[Conventional technology]

FIG. 2 is a vertical cross-sectional view of the top of the blast furnace showing an example of the occurrence state of the ore / coke (O / C) distribution deviation in the circumferential direction of the blast furnace caused by charging the raw material of the blast furnace shown in FIG.

The raw material charging of the conventional blast furnace is performed by using a plurality of furnace top bunkers 1 and 2 which are installed to face each other, a vertical chute 3 and a swiveling chute 4 which can be turned.

The raw material passing through the vertical chute 3 is selected as a dropping route at different positions in the vertical chute depending on which of the top bunkers 1 and 2 is discharged. As a result, a drift occurs and the distribution deviation in the circumferential direction of the furnace occurs. Cause That is, since the falling raw material falls to different positions on the swirling chute 4, the moving distance on the chute fluctuates as d ₁ and d ₂ due to the difference in the drift, which causes the moving time and the raw material leaving the chute. The fall velocity and the trajectory of the fall fluctuate, and finally the deposit position in the furnace fluctuates, and the distribution deviation of the charge in the peripheral direction of the charge layer, especially as seen in the profile of FIG. It leads to deviation of O / C distribution. In this case, a large deviation appears especially when the charging position of the raw material is extremely biased or when the type (particle size etc.) of the raw material is greatly changed.

As can be seen from the above description, when charging one kind of coke and one kind of ore, if the ore is cut out from one of the two furnace top bunkers 1 and 2 and the coke is cut out from the other, the alternating operation is continued. , Causes a large deviation in O / C distribution in the furnace circumferential direction.

In order to solve these problems, Japanese Utility Model Publication No. 59-5725 discloses a charging device in which two hoppers having discharge ports are vertically arranged on the central axis of the furnace. This device eliminates the circumferential unbalance but reduces the charging speed. Further, since the height of the device becomes high, there is a problem that equipment cost increases.

In Japanese Patent Publication No. Sho 61-30993, a cut gate is provided to restrict the flow in the vertical chute so that the raw material falls on the central axis of the furnace. Japanese Patent Laid-Open No. 53-102808 discloses a method in which a cone is provided above a vertical chute to prevent drift. All of these techniques attempt to control the trajectory of the raw material by narrowing the flow path through which the raw material falls.

[Problems to be Solved by the Invention]

It is not easy to completely eliminate the distribution deviation in the furnace with the method of adding a device to prevent uneven flow in the falling flow path of the raw material, and if a preventive device is added to the extent that it becomes complete, it will be on the cut gate and cone. The problem of causing shelving arises. That is, in order to effectively drop the raw material on the concentric shaft, it is necessary to significantly narrow the flow passage so that the raw material flows in the falling flow passage in a clogged state. Therefore, if the water content of the raw material fluctuates and the flow of the raw material deteriorates, clogging easily occurs, and it becomes difficult to control the charging of the raw material in a stable manner.

The present invention does not provide a drift prevention device in the flow path of the raw material, but tries to eliminate the distribution deviation in the furnace by changing the raw material charging cycle.

[Means for Solving the Problems]

The present invention is a bell-less blast furnace top blasting method in which three bunker tops are provided in parallel, and raw material is charged four times with 2 coke 2 ore 2 or coke 2 ore 3 or coke. 3 charge ore 2 charge any of 5 times, the above 3
It is a method for charging the top of a bellless blast furnace, wherein the raw materials are sequentially charged in the same order into individual bunker and then charged into the blast furnace.

This will be described in more detail with reference to FIG. FIG. 1 schematically shows a plane of three roof top bunker provided in parallel. Coke (C) and ore (O) were charged to the three bunkers L, M and N four times, one for coke 1 and one for ore 1 and 2 for ore 2 and coke 2. Or, if the charging of coke is 2 times and the charging of ore is 3 times, C and O entering the bunker L, M and N are as follows.

(A) When the number of times of charging is two, the bunker charge I II L C O M O C N C O (b) When the number of times of charging is four, the bunker charge I II III IV L C C O C M C C C O O N O C C O (c) When the charging number is 5, the bunker charge I II III IV V L C O C O O M C O O C O N O C O C O [Action] Three bunker L, M, N are sequentially charged into the bunker and discharged sequentially into the blast furnace. Except for 3 as shown in Fig. 1, 2 4 and 5, one cycle is obtained by repeating the charging times three times in succession, and in this one cycle, the bunker has the phases C and O in the same order in the mutually different phases.
Will be accepted and discharged. Therefore, at the time of each charging,
Even if there is a drift due to each bunker, the distribution of the contents in the furnace interior is homogenized in each direction when viewed from one cycle.

Furthermore, the number of furnace top bunker is set to 3 for the following reason. Normally, two furnace bunkers are installed 180 ° diagonally and symmetrical about the discharge direction. With two bunker, the number of times of charging is (C ↓ C ↓ O ↓) (coke 2 charged ore 1 charged) or (C ↓ O ↓ O ↓) (coke 1 charged ore 2 charged) 3 times Then, the distribution of C and O fractions is made uniform, but quantitative non-uniformity remains every 180 °. On the other hand, if three or four furnace top bunkers are installed, the unevenness can be eliminated every 120 ° and 90 °. On the other hand, if four bunkers are provided on the top of the furnace, it is difficult to fit the space for installing the bunkers on the top of the furnace and the exhaust valve, and the equipment cost becomes excessive. Also, with two bunker, the number of times of charging is limited, and C ↓ O during high production.
↓ O ↓ (1 charge of coke, 2 charges of ore) becomes difficult.
For the above reasons, the number of furnace top bunker must be three.

Charge number 4 (C ↓ C ↓ O ↓ O ↓) (coke 2 charge, ore 2 charge) compared to charge number 2 (C ↓ O ↓) (coke 1 charge, ore 1 charge) More charging modes are possible, which is a more desirable form. That is, it is possible to use different charging materials in the first and second coke charging C ↓. For example, in the first coke charging C ↓, a large particle size high quality coke and a second coke charging are used. It is possible to reduce the cost of raw materials by selectively using small particle size and low quality coke for C ↓. The same applies to ore.

Charges 5 (C ↓ C ↓ O ↓ O ↓ O ↓) (2 coke charges, 3 ore charges), or (C ↓ C ↓ C ↓ O ↓ O ↓)
Although (coke 3 charging, ore 2 charging) is desirable as a charging method, it has a problem that the number of charging is reduced by setting the number of times to 5 depending on the production amount. At least 3 bunkers are needed to achieve such multi-functionality.
A more desirable form is 4 and 5 times.

〔Example〕

The present invention was carried out in a blast furnace having a furnace volume of 4300 m ^{3 with} the number of charging times being 4 in one cycle. FIG. 3 (b) shows changes in the deviation σ of the eight skin flow thermometers 6 representing the circumferential uniformity of the upper part of the blast furnace 5 shown in FIG. 3 (a).

After implementing the present invention, the deviation sharply decreases to about 1/3. Further, as shown in FIGS. 3 (b), (c), and (d), the changes in the hot metal temperature and [Si] are reduced, and it can be seen that the non-uniformity in the circumferential direction is eliminated. Moreover, since the fluctuation of the hot metal temperature is reduced, the average hot metal temperature can be lowered, and the hot metal temperature is lowered to about 1493 ° C. As a result, [Si]
It has decreased by 0.2%, and the economic effect of this is remarkable.

〔The invention's effect〕

According to the present invention, it is possible to eliminate the non-uniformity of the temperature in the circumferential direction of the blast furnace, which is peculiar to the bellless blast furnace, and as a result, it is possible to eliminate the deviation between the hot metal [Si] and the hot metal temperature for each tap hole. .

[Brief description of drawings]

FIG. 1 is an explanatory view showing the contents of a cycle of an embodiment of the method of the present invention, FIG. 2 is a vertical sectional view of the vicinity of the top of a bellless blast furnace, and FIG. 3 is a graph showing the effect of the present invention. 1, 2 …… Burker on the top of the furnace, 3 …… Vertical chute 4 …… Swirl chute 5 …… Blast furnace 6 …… Skinflow thermometer L, M, N …… Bunker, C …… Coke O …… Ore

Front Page Continuation (72) Inventor Takeshi Uchiyama 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Technical Research Headquarters (56) Reference JP-A-63-100113 (JP, A)

Claims (1)

[Claims] 1. A method for charging a bell-less blast furnace, wherein three furnace bunkers are provided in parallel, and raw materials are charged four times by charging two cokes and two ores, or charging two cokes and two ores. Alternatively, the coke 3 charging ore 2 charging is performed 5 times, and the raw materials are charged in the same order in the same order in the 3 bunker and charged into the blast furnace. How to enter.