JPH0254706A - Method for operating blast furnace - Google Patents

Abstract

PURPOSE:To easily execute blast furnace operation matching to the aimed operating condition by charging while adjusting mixed material of ore kind and coke kind when the layer thickness ratio of the ore kind and the coke kind at the furnace wall side exceeds the specific value at the time of executing in order layer charge of only the ore kind and layer charge of only the coke kind. CONSTITUTION:A furnace top bunker 2a for the ore kind, furnace top bunker 2b for the coke kind and a furnace top bunker 2c for the mixed material of the ore kind and the coke kind are arranged so as to be possible to charge in the blast furnace 1 with a swing chute 4 through flow adjusting gates 3, respectively. By this constitution, the coke kind and the ore kind are charged into the blast furnace 1 in order layer by layer and the average layer thickness in the range of <= about 700mm from the wall side in the blast furnace is measured with the measuring instruments 5, 5a. When the ratio (Lo/Lc) of the ore layer thickness (Lc) and the coke layer thickness (Lc) exceeds 1.20, the charging quantity and charging position of the mixed material of the ore kind and the coke kind are adjusted and charged in accordance with the layer thickness ratio. By this method, the stable and good blast furnace operation is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a method of operating a blast furnace in which a mixture of coke and ore is charged using a rotating chute.

[Conventional technology 1] In blast furnace operation, one of the important elements for stable and good operation is to maintain the gas flow distribution and gas permeability in the furnace in an appropriate state. −Solid heat・
One example is efficient exchange and reduction of raw materials.

For this purpose, in order to control the gas flow in the furnace by utilizing the difference in gas ventilation resistance between ores and coke, when charging the furnace in layers, ore and coke are separated in the radial direction of the furnace. The layer thickness ratio has been adjusted, and in blast furnaces with rotating chutes inside the furnace, when ore and coke are charged in more than a dozen turns, they are charged using different combinations of tilting angles of the rotating chutes. The above layer thickness ratio is adjusted by inputting the above.

However, recent blast furnace operations have strict requirements such as production adjustment, hot metal composition control, and adjustment to a target fuel ratio based on the energy balance within the steelworks, and the above method of adjusting the layer thickness ratio alone is not sufficient to ensure stability. It was difficult to carry out the blast furnace I%￥ business.

Therefore, in order to add a new burden distribution means, in Japanese Patent Application Laid-Open No. 52-96916, a mixture of coke and ores is transferred from the furnace wall on the surface of the top charge when charging raw materials to a blast furnace having a rotating chute. A method of charging blast furnace raw materials has been proposed in which the blast furnace raw materials are charged inside concentric circles at a distance of 500 mm to reduce ventilation resistance in the cohesive zone region where the ore is in a semi-molten state.

[Problem to be solved by the invention 1 However, the furnace wall on the surface of the type M charge is simply 6500 mm.
The charging method in which mixed raw materials are repeatedly charged inside concentric circles at a distance of , has the following problems.

(1) Although there is an effect of lowering the ventilation resistance in that area and lowering the overall ventilation resistance, if the ventilation resistance in that area is unnecessarily reduced significantly, the gas flow rate increases and the gas and solid Heat exchange and ore reduction efficiency may decrease and the fuel ratio may increase.

■ In the radial gas flow distribution in the furnace, the gas flow toward the furnace wall is extremely suppressed, leading to a lack of heat and the formation of an inert region on the furnace wall, which prevents the stable descent of the charge and its failure. There are concerns that the tuyeres may be damaged when active materials fall.

(2) Therefore, the mixed charging method, which is an effective charging method, cannot be used effectively in order to reduce the ventilation resistance in the cohesive zone portion.

[Means for solving the problem] In order to solve the above-mentioned drawbacks, we analyzed past blast furnace operation data and found that in layered charging of coke and ore, the ore layer thickness (LO) on the furnace wall side Coke layer thickness (Lc)
When the layer thickness ratio (L o / L c ) exceeds 1.20, slippage, so-called irregularity in the descent of the charge, increases, fluctuations in the top gas composition increase, and the amount of gas passing through the furnace increases. Proper distribution in the radial direction cannot be obtained, etc.
It was discovered that blast furnace operations were rapidly becoming unstable.

Therefore, in the present invention, when the value of L o / L c is less than 1.20, it can be dealt with by normal layer thickness adjustment of L o / L c, but when it is 1.20 or more, it is impossible to increase the layer thickness of the ore. There is a limit, and in order to stabilize operation, L0/L near the wall
Since the conventional distribution control wholesaler that adjusts By adjusting the charging amount and charging position, it is possible to easily optimize gas distribution control, which was conventionally difficult to do by simply adjusting L o / L c near the wall.

That is, the present invention provides a blast furnace operating method in which raw materials are charged using a rotating chute, and stratified charging of only ores, stratified charging of only coke, and stratified charging of a mixture of coke and ores is performed. When the layer thickness ratio of ore and coke on the furnace wall side exceeds 1.20 in layered charging of only ores and layered charging of only coke, charging of the mixture according to the layer thickness ratio. It is characterized by adjusting the amount and charging position.

FIG. 1 is an explanatory diagram of the operating method of the present invention.

The blast furnace 1 is equipped with a top bunker 2 for coke, ores, and a mixture, and each top bunker is provided with a flow control gate 3 for adjusting the charging amount of each raw material. By setting the tilt angle θ of the chute of the rotating seat 4 that charges each charge into the furnace, each charge can be charged at any position in the radial direction of the furnace. It is.

The furnace contents layer thickness measuring device 5.5a measures the average layer thickness within a range of 700 mm from the wall inside the blast furnace. As long as the layer thickness can be measured at least at one fixed point within the above range, the zero layer thickness measuring device 5.5a may be a mechanical sounding meter or micrometer that measures the distance from a certain level to the surface of the charge. A general device such as a wave-type sounding meter may be used, but a microwave type that can continuously measure each charge is preferable.

Fixed temperature sonde 6 is a measuring device for detecting gas flow distribution within the furnace. This device is not limited to the fixed temperature sonde 6, but can also measure gas components in the radial direction with a shaft sonde and heat extraction from a stave.

Any measuring device that detects the gas flow in the furnace, such as a furnace body thermometer, may be used, and it is preferable to combine these measurement results to determine the gas flow distribution in the furnace.

In the present invention, a table as shown in Table 1 is prepared in which the charging action of the charging mixture is determined according to the value of Lo/Lc near the wall, and the charging action is carried out in accordance with the table. 1st
The boundary values and action 1 in the table are the size of the blast furnace being operated,
0 Normal L that requires modification depending on the properties of the raw fuel used
If o/Lc is not a large value, the charging mixture should be placed in the center of the furnace as much as possible, with the minimum amount required.
The coke ratio in the mixture is preferably 15 or more, considering the amount consumed by the solution loss reaction up to the cohesive zone and the effect of reducing ventilation in the cohesive zone.A+ Layer thickness measuring device 5.5a Based on the layer thickness measurement results, actions are taken according to Table 1, but one layer thickness measurement is performed for each charge (each batch), and the mixture charging action,
An average value of at least 10 charge measurements is used to perform the reversal action. When charging a mixed charge, it is preferable not to change the total amount of coke and ore in one charge (coke, raw ore, raw mixture) as this will reduce fluctuations in blast furnace operation. .

For mixed charging, as shown in Fig. 1, in addition to the ore top bunker 2a and the coke top bunker 2b, a mixed charging top bunker 2C is provided to transfer the pre-mixed mixture to the type m bunker. Alternatively, the lower flow control gates 3 of the coke top bunker 2a and the ore top bunker 2b may be simultaneously opened as many times as necessary to allow mixing.

Needless to say, the position at which the mixture is introduced into the blast furnace is adjusted by adjusting the tilting angle θ of the rotating chute 4.

[Example 1 An example of an embodiment of the present invention is shown.

The internal volume of the blast furnace used was 4,500 rrl', and a microwave level meter was installed at the top of the furnace to measure the thickness of the charge layer at a position 6,500 mm inside the furnace wall. In order to determine the gas flow distribution, a fixed temperature probe was installed in the furnace to measure the gas temperature in the radial direction. are measured continuously.

The blast furnace used was a bellless type blast furnace with a rotating chute.
The three furnace bunkers make it possible to charge only coke, only ore, and a mixture of coke and ore.

FIG. 2 shows the operational history in which charge distribution control was performed using the present invention. Charge distribution action is carried out in the area marked with 1 in Figure 2.

Blow rate: 600 ONITll/min Ores: 1141;/Charge coke=34/Charge was charged in a layered manner. The charge distribution control action will be explained below.

(1) ■The amount of heat removed from the action stave is the control value (400 to 600 x 10'
kCal/H) was below the lower limit, so the amount of gas passing through the furnace wall decreased.

This is a normal action taken by reducing the amount of ore charged near the furnace.

(2) Action (2) In order to cope with the large increase in the amount of heat removed from the stave due to the increase in the amount of air blown, this action is to charge a large amount of ore to the furnace wall side in order to suppress the gas passing through the furnace wall ll111. (114 tons for ores only, 34 tons for charge and coke only)
/Charge) (3) Action of ■ With the action of ■, the ore layer thickness on the furnace wall side increases, and L
Since o/Lc exceeded 1.2 and the amount of heat extracted from the tape exceeded the control upper limit, a mixture was charged in accordance with Table 1 to increase the amount of gas passing through the center of the furnace. (Ores only 106t/charge, coke only 32t/charge, mixture 10t/charge, (
8t of ore/charge, 2t of coke/charge)) Charge the mixture as shown in Table 1! The tilting angle θ of the rotating chute 4 was set to 0 so that <0.2.

(4) Action ■ From the action ■, L o / L c was around 1.20 and the amount of heat extracted from the stave was stable within the control value, but as the air flow rate further increased, it became necessary to remove the stave. fever rises,
As a solution to this problem, more ores were charged near the wall in order to suppress the amount of gas passing through the furnace wall.

(5) Action ■ In the action ■, L o / L c exceeds 1.30 and the amount of heat extracted from the stave is still high, so in order to increase the gas in the center of the furnace, the charging of the mixture at the center position is started. Increased according to Table 1.

(f, stone only 98t/charge, coke only 30t
t/charge, mixture 20t/charge, (ore 16t
, /charge, coke 4t/charge)) Due to the increase in the charging amount of the mixture, when charging the mixture into the furnace, the tilting angle of the rotating chute θ = O as in the action of Charging was carried out at 0=5 degrees, and the charging was carried out uniformly within the range of ε<0.4 shown in Table 1 to prevent segregation in the center portion.

(6) Due to the effect of the action ■, the amount of heat extracted from the stave was reduced, so the amount of ore charged near the wall was reduced.

(7> Action of ■ As a result of the action of ■, the amount of heat removed from the stave increased slightly, but since L o / L c decreased to 1.20 within the control value, the amount of charge of the mixture in the center of the furnace was reduced. It was (■
action).

(8) Actions of ■ and ■ This is a return action similar to ■ and ■ actions.

The above is an example of operation, and stable blast furnace operation is continued by controlling the charge distribution according to the present invention.

The contents of the mixture charging actions shown in Table 1 are reviewed periodically as operations continue.

[Effect of the invention 1: In a blast furnace with an internal volume of 4500 rn', the air blowing temperature is set at 850°C.
~900℃, set air flow rate 6000~6300 Nrn'
Foil operation was carried out at a fuel ratio that matched the in-plant energy balance under the operating conditions of 22 OxlO3 t/min and a pig iron output of 22 OxlO3 t/month, and the following effects were obtained by the present invention.

■ Furnace [100] Fluctuations in gas components are small (and the variation in gas utilization rate + 7 CO2 CO2/ (CO2 + CO) at the top of the furnace is reduced as shown in Figure 3. Also, fluctuations in operation are reduced, The fourth factor is the variation in the difference between blast pressure and furnace top pressure.
It decreased as shown in the figure.

(2) As a result, the variation in the degree of [Si]in in the hot metal was reduced as shown in Figure 5, and the quality of the hot metal was stabilized.

By reducing operating fluctuations in this way, it has become easier to operate blast furnaces in accordance with target operating conditions.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the present invention, Fig. 2 is an example of an operating method using the present invention, Fig. 3 is a reduction in fluctuation in the furnace top gas utilization rate, Fig. 4 is a reduction in fluctuation in blowing pressure, Figure 5 shows hot metal [5i
It is a figure showing the fluctuation reduction of la degree. l... Blast furnace 2... Furnace rI bunker 2a... Furnace top bunker 2b for ore type 6... Furnace m bunker 2c for coke... Furnace top bunker 3 for a mixture of ore and coke. ...Flow control gate 4...Swivel chute 5.5a...Layer thickness measuring device 6...Fixed? Sonde for goods

Claims (1)

[Claims] 1. In the blast furnace operation method in which raw materials are charged using a rotating chute and stratified charging of ores only, stratified charging of coke only, and stratified charging of a mixture of coke and ores is carried out, In layered charging and layered charging with only coke, the layer thickness ratio between ore and coke on the furnace wall side is 1.20.
A method for operating a blast furnace, which comprises adjusting the charging amount and charging position of the mixture according to the layer thickness ratio when the ratio exceeds the layer thickness ratio.