KR0146794B1 - Furnace coke diameter managing method - Google Patents

Abstract

The present invention relates to a particle size management method of coke, a fuel used in the blast furnace refining process, by operating a coke sampler that collects coke in the furnace through a blast furnace at the time of regular blast furnace repair. Sampling the coke in the blast furnace for each condition, and then obtained the average particle diameter to perform the symptom tube analysis, and then to create a mouthball location coke particle diameter formula, and to provide a method for managing the particle size of the blast furnace location coke using this purpose, have.

The present invention for achieving the above object is to calculate the falling rate of the charge according to the powdered coal injection amount and the molten iron production amount using the following formula (I, II, III); And,

Descent speed by ore

= (Ore loading / ore density + coke loading / coke density) / blast furnace cross section ... (Ⅰ)

Dropping speed due to coke = (coke loading / coke density) / blast furnace cross section ... (II)

Descent rate of charge = descent rate by ore + descent rate by coke ... (Ⅲ)

Making a regression equation such as the following equation (IV) using the dropping rate of the charge and the coke quality after reaction, mechanical strength, average particle size before loading

Fine-cured coke particle size = -0.0423RT + 1.2MS + 1.5DI + 0.48CSR-196 ... (Ⅳ)

(Here, RT: Coke furnace residence time, MS: Charged coke average particle diameter

DI: Charge coke mechanical strength CSR: Strength after charge coke reaction)

The gist is to provide a particle size management method of the blast furnace location coke comprising a.

Description

How to manage particle size of blast furnace coke in blast furnace

1 is a schematic view showing the general behavior of the blast furnace charge.

2 is a graph showing the relationship between the descent rate of blast furnace charges, (a) molten iron production, and (b) pulverized coal injection rate.

3 is a graph showing the relationship between the average particle diameter of the blast furnace coke in the blast furnace and the residence time.

4 is a graph showing the relationship between the particle size of the blast furnace coke in the blast furnace, (a) the strength after the charging coke reaction, and (b) the average particle size of the charging coke.

FIG. 5 is a graph showing changes in coke characteristics, furnace ventilation index, and furnace passage gas volume as an example to which the method of the present invention is applied.

* Explanation of symbols for main parts of the drawings

1: Coke layer in blast furnace 2: Iron ore layer in blast furnace

3: blast furnace charging mouth 4: pulverized coal injection lance

5: ventilation pipe 6: core

7: lead and fusion zone 8: combustion zone

9: coke sampler

The present invention relates to a particle size management method of coke, which is a fuel used in the blast furnace refining process, and more particularly, to a method for managing the particle diameter of the blast furnace location coke for ensuring the ventilation in the furnace through the appearance management of the coke. .

In general, in blast furnace operations, coke is sampled from the tuyere by operation conditions and charged coke properties, and the particle size is analyzed to obtain the average particle diameter of the coke-shaped coke. The formula is formulated and used to manage the particle size of the coke flakes to promote stable operation of the blast furnace.

1 is a schematic view showing the behavior of the blast furnace charges, iron ore (2) raw material for the production of pig iron and coke (1) fuel is charged into the layer at the top of the blast furnace, and the high temperature through the air vent located in the bottom of the blast furnace Hot air is blown in and the coke 1 is burned. At this time, pulverized coal, which is auxiliary fuel, is blown through the tuyere with blowing air. The iron ore (2) charged to the top is continuously reduced, and is heated and reduced, semi-melted in the fusion fusion zone (7), and is present in the molten state below the fusion fusion zone (7) so that there is almost no volume. The coke (1), which is a fuel, continuously descends and is burned (8) in the cavity of the wind bulb, and the reducing gas generated therethrough passes between the charges in the blast furnace to reduce the iron ore (2) and is discharged to the furnace.

On the other hand, according to the results of the dismantling investigation (iron and steel, 70, 16, p2216-2223), the coke (1) showed a rapid decrease in particle size from the soft fusion zone (7) or less, and the soft fusion zone (7). In the center below, there appeared to be a core 6 consisting of coke with little movement. Thus, the charging coke passes between the core and the furnace walls. The role of coke in blast furnaces can be divided into three categories.

The first is to serve as a heat source for melting iron ore in the blast furnace. The coke burns in the blast furnace cavity and generates heat.

Iron ore requires a reducing agent to reduce iron as it exists as an oxide, and the second of the role of coke serves as a source of reducing agent required for this. At present, however, steel mills replace coke's role as a heat source and reducing agent by injecting pulverized coal through a tuyere to reduce the amount of molten iron.

Increasing the amount of pulverized coal injection decreases the consumption rate of coke in the furnace, and the delay of the consumption rate of cocos according to the pulverized coal injection means that the residence time in the blast furnace is increased and the probability of relative fragmentation increases. Therefore, it is difficult to secure the air permeability of the gas, molten molten iron, slag in the blast furnace due to the increased amount of coal dust blown.

Therefore, in the case where the amount of pulverized coal injection increases, appropriate coke size management is required to ensure ventilation in the furnace.

In order to examine the behavior of coke in the furnace, steelworks in various countries such as Pohang Iron and Steel have conducted the demolition investigation by cooling the blast furnace, and another method is to collect and analyze the coke with the coke sampler through the blast furnace during regular repair. The characteristics of coke depending on the conditions are examined.

In the Japanese steel pipe (Japan Ogyo Kobo, No. 60, 1990), blast furnace decommissioning investigations reported that the reduction of coke size increased the fraction of coke, which increased air permeability and increased melt retention such as slag and molten iron. Specifically, when the coke particle diameter decreased by 2 mm, the ventilation resistance increased from 3.1 to 3.3.

As described above, in the blast furnace operation, cocos plays a role of reducing gas and heat source, and maintaining breathability. Breathability is an essential item to be managed for stable operation of blast furnaces, and there are many other factors that will change. Among them, the coke particle size plays a decisive role, and if the coke particle size is effectively managed, the blast furnace operation can be stably maintained.

Conventional methods for managing the particle size of the lower blast furnace coke are based on the results of experiments at constant temperature and gas composition without considering changes in temperature and gas composition in the blast furnace, and changes in temperature and gas composition experienced by coke in the furnace. In the case of experimenting on the change of coke properties based on the pattern, there is a method according to the Korean Patent Application No. 94035002.

Among the various methods described above, the result of the test at the constant temperature and gas composition has a problem in that coke property management cannot be performed due to the change in the amount of pulverized coal injection and the molten iron production, without considering the influence of the operating conditions.

In the case of investigating changes in the blast furnace temperature and gas composition by operating conditions and patterning them to simulate the differentiation of coke on the basis of this, the management of coke is more accurate than the above-mentioned constant temperature and gas composition. Evaluating the degree of differentiation after chemical change such as gasification reaction has the disadvantage that the error occurs according to the experimental estimation of the physical force.

In addition, the method of Korean Patent Application No. 94-35002 excludes the degree of differentiation of coke by mechanical force, so it is not possible to accurately evaluate the degree of differentiation according to the overall characteristics of coke before charging, and thus it is not possible to accurately manage the coke size. have.

As a means of demonstrating the above results, there is a dismantling investigation method that examines the condition of the furnace by cooling the blast furnace with an inert gas, but this is only possible once at the end of the blast furnace life. There is this.

Thus, the present inventors have conducted research and experiments to solve the above problems and proposed the present invention based on the results. The present invention operates a coke sampler which collects the coke in the furnace through the blast furnace during regular repair. Sampling coke in the blast furnace blast furnace by operating conditions such as pulverized coal injection ratio, molten iron production, etc. To provide a way to manage the particle size of the purpose is to.

Hereinafter, the present invention will be described.

In order to achieve the above object, the present invention provides a blast furnace operation method for preparing iron ore and coke into the hearth part and blowing pulverized coal from the tuyere, to set an optional ore loading amount and coke loading amount according to the operating conditions;

Obtaining a dropping rate of the charge by the following formulas (I ~ III) using the set amount of ore and coke;

[Descent rate due to ore

= (Ore loading / ore density + coke loading / coke density) / blast furnace cross section] ... (Ⅰ)

[Descent velocity by coke = (coke loading / coke density) / blast furnace cross section] ... (II)

[Deposition rate of charge = descent rate by ore + descent rate by coke] ... (III)

Obtaining the residence time (RT) of coke by the following equation (IV) using the dropping rate of the charge obtained as described above;

[Dwell time in coke furnace = furnace height / load drop rate] ... (IV)

Obtaining the charging coke average particle size (MS), the charging coke mechanical strength (DI) and the strength after charging coke reaction (CSR) in a conventional manner; And substituting the coke furnace residence time (RT), the charged coke average particle diameter (MS), the charged coke mechanical strength (DI), and the strength after charging coke reaction (CSR) obtained by the above equation (V). It relates to the particle size management method of the blast furnace location coke in the blast furnace, characterized in that it comprises a step of adjusting the charging conditions so that the obtained, and the obtained bulbous coke particle size is maintained at an appropriate level.

[Bubble Coke Particle Size = -0.0423RT + 1.2MS + 1.5DI + 0.48CSR-196] ... (Ⅴ)

Hereinafter, the present invention will be described in more detail.

In order to achieve the above object, in the present invention, as a result of the blast furnace dismantling investigation, it was found that the coke differentiation in the furnace occurs mostly below the soft fusion zone. This differentiation is largely CO ₂ carbon coke consumption by the reaction: takes place by _{(Carbon Solution loss CO 2 + C} → 2CO) and two kinds of factors of the mechanical strength due to the own weight of water charged. After all, the factors that determine this differentiation depend on the length and duration of coke residence time in the furnace.

In the present invention, the following method was used to calculate the residence time by using the results of the above blast furnace decommissioning investigation. The solid ore melts in the fusion zone and turns into a liquid, so there is no volume of melt at the bottom of the fusion zone. That is, only the ore is consumed in the upper part of the blast furnace, and thus the loading drop speed can be represented by the following equation (I-III).

Descent speed by ore

= (Ore loading / ore density + coke loading / coke density) / blast furnace cross section ... (Ⅰ)

Dropping speed due to coke = (coke loading / coke density) / blast furnace cross section ... (II)

Descent rate of charge = descent rate by ore + descent rate by coke ... (Ⅲ)

The sum of the drop rates of the charges obtained by the above formulas (I) and (II) gives the drop rates of all the charges of the formula (III).

Figure 2 shows the relationship between the dropping rate of the total load, the amount of molten iron production and the fine coal injection, wherein the increase of the amount of molten iron increases the rate of falling of the charged material, and the increase of the fine coal injection reduces the coke consumption rate. It can be seen that it reduces the rate of descent of water.

Since the coke charge and ore charge are both related to the residence time of coke in the furnace, the above-mentioned fuel charges (coke, ore) are charged and the residence time is converted into the following equation (IV). ) Was investigated in the coke particle diameter of the blast furnace and the results are shown in FIG.

[Dwell time in coke furnace = furnace height / load dropping speed] ... (Ⅳ)

FIG. 3 shows the descent velocity by the above formula (I) (II) with the amount of fine coal blown and molten iron produced at the time of coke sampling, and converts the retention time of the charge based on 25 m of the labor, and collects the wind collected by the coke sampler. The average particle diameter of the spherical coke was obtained and the relationship between the residence time and the diameter of the spherical coke was shown.

As can be seen in FIG. 3, the particle size correlates with the residence time of the charge, but it can be seen that the large variation has other factors that determine the coke particle size. Among these factors, the coke appearance of the charge is an important factor.

FIG. 4 shows the relationship between the coke properties of charged materials and the blast furnace coke size.The relationship between the strength after the reaction of charged coke (CRS) and the average particle size (MS) of the coke before charging and the size of the coke sized coke It is shown.

As can be seen from FIG. 4, it can be seen that the improvement of the characteristic value of the coke before charging causes an increase in the coke particle size on the tuyere.

Therefore, the characteristics of the coke with the post-reaction strength, the average coke size before loading, and the mechanical strength (DI) of the charged coke are shown in FIG. A cross-correlation analysis was conducted to investigate. At this time, the reaction rate of coke in the characteristic value of coke was excluded from the correlation analysis because it has a completely inverse correlation with the strength after the reaction of coke.

As a result of heavy correlation analysis by the conventional method as described above, a regression equation was obtained as in the following formula (V).

Weather-like coke particle size = -0.0423RT + 1.2MS + 1.5DI + 0.48CSR-196 ... (V)

(Here, RT: Coke furnace residence time, MS: Charged coke average particle diameter

DI: Charge coke mechanical strength CSR: Strength after charge coke reaction)

In the present invention, when the blast furnace is operated, the particle diameter of the furnace-shaped coke according to the operating conditions is estimated by using the above formula (V), and then control is performed to the desired coke particle size. Coke particle size control to a desired degree is common by controlling the compounding ratio of the coke to be blended to control MS, DI, CSR and the like. By such adjustment, the particle size of the tuyere position coke is controlled to facilitate the management of air permeability at the lower part of the blast furnace, thus enabling stable blast furnace operation.

Hereinafter, the present invention will be described in more detail with reference to Examples.

EXAMPLE

The present invention is used to estimate the bottom coke particle size and to accurately manage in-vehicle breathability. Ergun (Chem. Eng. Prog., 48, 1952) and others have a constant airflow resistance when gas passes through a fluidized bed filled with solid particles, such as blast furnaces.The main factor is the particle size of the charged particles, which reduces the particle size by 2mm. The air flow resistance increased by 1.2 times.

In order to confirm the air permeability of the furnace by the method of the present invention, as shown in FIG. 5, the coke furnace residence time (RT), the charged coke average particle diameter (MS), the strength after charging coke reaction (CSR) and the charged coke mechanical strength (DI) After calculating the blast furnace coke particle diameter according to the above equation (V), substitute the result into Ergun eq. Indicated by dotted lines.

As can be seen in FIG. 5, it can be seen that the change value of the airflow index to which the method of the present invention is applied is substantially the same as the change value of the airflow index by actual measurement. From this, it was proved that the equation for estimating the bottom coke particle size according to the change of coke shape proposed by the present invention is very accurate.

As described above, in the present invention, it is easy to manage the air permeability during the operation of the blast furnace by accurately measuring the particle diameter of the coke coke in the furnace according to the change of the particle size of the coke, and thus has excellent work stability.

Claims (1)

A blast furnace operation method for charging iron ore and coke into the hearth section and pulverizing pulverized coal from a tuyere, the method comprising: setting an ore loading amount and a coke loading amount according to operating conditions; Obtaining a dropping rate of the charge by the following formulas (I to III) using the set amount of ore and coke; [Descent rate due to ore = (Ore loading / ore density + coke loading / coke density) / blast furnace cross section] ... (I) [Descent velocity by cocos = (coke loading / coke density) / blast furnace cross section] ... (II) [Descent speed of charge = descent speed by ore + descent speed by coke] ... (III) Obtaining a residence time (RT) of coke by the following formula (IV) using the dropping rate of the charge obtained as described above; [Dwell time in coke furnace = furnace height / load drop rate] ... (IV) Obtaining the charging coke average particle size (MS), the charging coke mechanical strength (DI) and the strength after charging coke reaction (CSR) in a conventional manner; And substituting the coke furnace residence time (RT), the charged coke average particle diameter (MS), the charged coke mechanical strength (DI), and the loaded coke strength (CSR) in the following formula (V). Obtaining, and adjusting the charging conditions to maintain the obtained wind bulb coke particle diameter at an appropriate level, the particle size management method of the blast furnace position coke in the blast furnace. [Bubble Coke Particle Size = -0.0423RT + 1.2MS + 1.5DI + 0.48CSR-196] ... (V)