KR100212026B1 - Method for comtrol coke according to input volume of pulverized coal - Google Patents

Abstract

The present invention relates to a coke management method according to the change of the pulverized coal injection amount, in particular to the coke management method according to the change of the pulverized coal injection amount to adjust the amount of coke changes according to the amount of pulverized coal injected into the blast furnace. And (1,2) deriving a relationship in which the gas composition and temperature distribution in the furnace and the dropping rate of the charge can be set in advance according to the change in the blast furnace operating conditions such as the change in the amount of pulverized coal injection. Simulation (4,5) of the differentiation characteristics of the coke in the blast furnace according to the different quality according to the coke differentiation index of the blast furnace according to the change in the amount of pulverized coal and the coke quality change using the simulation step (4,5) Step (6) to prepare a relation and diagram that can calculate the and to be charged into the blast furnace when the pulverized coal injection amount changes using the relation and diagram prepared in the step (6) Step 7 is to set the appropriate coke quality to be done.

Description

How to manage coke according to the change of pulverized coal injection

1 is a schematic diagram of the blast furnace.

2 is a Bosch coke particle size estimation flowchart in accordance with the present invention.

3 is a graph showing simulated experimental conditions for practicing the present invention.

4 is a schematic diagram of a simulation test apparatus for implementing the present invention.

5 is a graph showing the change of coke differentiation index different from the amount of pulverized coal blown and the coke quality change in the simulation results through the embodiment of the present invention.

Figure 6 is a graph showing the change in the coke average particle size according to the change in the amount of fine coal injection and coke quality of the simulation results through the embodiment of the present invention.

FIG. 7 is a graph showing the relationship between changes in the coke differentiation index according to the change of CSR and the amount of pulverized coal blown using the simulated experimental results through the embodiment of the present invention.

8 is a graph showing the relationship between the change in the coke differentiation index according to the DI change and the amount of pulverized coal blown by using the simulation results through the embodiment of the present invention.

9 is a graph showing the relationship between the change in coke differentiation index according to the change in the average particle diameter of the charged coke and the amount of pulverized coal injection made using the simulation results through the embodiment of the present invention.

10 is a graph showing the relationship between the coke differentiation index and the combustion furnace depth measurement results according to the present invention.

11 is a graph showing the relationship between the coke differentiation index and the airflow resistance index according to the present invention.

* Explanation of symbols for main parts of the drawings

1: route 2: coke

3: iron ore 4: softening fusion zone

5: core 6: burning zone

7: slag 8: molten iron

9: bosch part 10: windball

11: exit port 12: container

13: reaction tube 14: heating portion

15 gas inlet 16 gas discharge

17: motor 18: chain

The present invention relates to a coke management method according to the change of the pulverized coal injection amount, in particular to the coke management method according to the change of the pulverized coal injection amount to control the amount of coke changes according to the amount of pulverized coal injected when pulverized coal is injected into the blast furnace. It is about.

In general, coke is produced by carbonizing raw coal, and its main component is carbon, which is a reducing agent for reducing the heat source and iron ore required for blast furnaces. Used. In addition, it serves to ventilate and liquidize the blast furnace.

As described above, fine coal is used as a source of heat and a reducing agent among the main roles of the conventional coke, thereby replacing the role thereof. That is, by directly injecting auxiliary fuel such as pulverized coal through the wind hole (風口, 10), the amount of coke charged through the road (爐 頂, 1) is reduced.

This causes a problem that the role sharing of the coke becomes larger because a passage through which the gas and the melt (slag 7 and the molten iron 8) in the blast furnace can pass with a relatively small amount of coke.

However, in order to obtain economic effects by using pulverized coal which is relatively inexpensive compared to the price of coke, and to maintain stable blast furnace operation, a blast furnace operation method capable of maintaining good ventilation and liquidity in blast furnaces is required.

By the way, the coke is reduced in size and lowered in strength due to physical causes caused by friction between chemical reactions and charges in the blast furnace. The differentiation and deterioration of the coke in the blast furnace will have a direct effect on the aeration and liquid permeability described above, and will interfere with stable operation and smooth production. For this reason, the quality of coke charged into the blast furnace should be managed according to the appropriate standards according to the change of blast furnace operation conditions such as pulverized coal injection.

Conventionally, in accordance with the change in conditions of blast furnace operation such as pulverized coal injection, the criteria for managing coke are set in consideration of the environment that coke is received in the blast furnace, or the standard is set through a fragmentary experimental operation. For example, in order to maintain the same combustion zone depth by measuring the depth of the combustion zone when all the operating conditions are kept constant, and the amount of pulverized coal injection is increased, the coke's cold strength index (DI, Drum Index, etc.) may be adjusted to some extent. Coke management criteria have been proposed to be improved and managed (CAMP-ISIJ., Vol. 6, p. 26 (1993)). In addition, coke that is charged to maintain the coke particle size of the Bosch part 9 at a certain level was also managed (for example, Skantrofu blast furnace of British Steel Corporation). However, in the former case of this method, other operating conditions, for example, production speed, quality of iron ore excluding coke, and blowing conditions should be kept constant in order to derive the management criteria. It is very difficult to maintain. In addition, the actual operation blast furnace proposed in these methods has a problem that it is very difficult to maintain such conditions. In addition, there is a big problem in that separate equipment is required to measure the depth of the combustion zone 6 and the coke particle size of the Bosch part in the actual operation blast furnace proposed in these methods, and the process is very cumbersome.

In addition, as an index indicating the quality of the coke, DI, a rotational strength characteristic value, is used to represent the mechanical differentiation characteristics of the coke in a low temperature zone, that is, the upper part of the blast furnace. This is a certain amount of rotation (usually 10 kg) and a certain particle size (typically 50 mm or more) of coke in a fixed size rotating cylinder (回轉 筒, drum, diameter 1.5Φ, length 1.5m) and then rotates for a certain time (usually 15rpm, 10 Coke strength after Reaction (CSR) is used as an index for evaluating the quality of coke in the high temperature zone of the blast furnace. Sometimes. In the reaction tube 13, carbon dioxide (CO ² ) is 100 ( After reacting 200 (g), 20 (mm) coke with 2 ℃ under 1100 ℃ using reactant gas which is), it is set as Coke Reaction (CRI) based on the weight loss of coke. One sample is placed in a rotating tube and rotated at 20 (rpm) for 30 minutes, and then the CSR is expressed as a percentage of the weight ratio of coke 10 (mm) or more. However, the method of managing the coke quality was limited to a certain condition so that there was a limit in accurately estimating the differentiation characteristics of the coke according to the change in blast furnace operation and managing the coke based on that.

The present invention improves the conventional coke management problem as described above, and provides a different coke management method to the change of the amount of fine coal injection that can manage coke efficiently in the blast furnace injecting pulverized coal in a simpler way. have.

The present invention is configured to achieve the above object.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings.

First, the schematic diagram of the blast furnace is shown in FIG. Iron ore 3, which is a raw material of the molten iron, 8 and coke 2, which is a fuel, are charged into the layer in the furnace 1, and hot air is blown through the tuyere 10 located at the bottom of the blast furnace. Blow the wind and burn the coke (2). At this time, the pulverized coal as an auxiliary fuel may be blown together with the blowing through the tuyere 10. This combustion reaction generates heat and reducing gas, whereby iron ore is dissolved and reduced. The molten iron 8 and the slag 7 which are produced | generated are accumulated in a furnace, and are discharged | emitted out of a blast furnace periodically through a tap opening 11. Iron ore in the solid state charged into the top 1 is reduced and softly fused in the process of descending to the lower part of the furnace, and finally exists as a melt below the softened fusion zone 4. However, coke forms a core 5 in the core as well as in the bulkhead, which is the upper portion of the softened fusion zone 4. In other words, coke exists in the solid state not only in the bulk, but also in the bottom, and for this reason, the coke plays an important role in the breathability and liquidity in the blast furnace.

Bosch coke is coke that flows into the combustion zone (6) as coke existing in the bosch part (9).

FIG. 2 is a flowchart showing the flow of the coke amount management method according to the change in the blast furnace pulverized coal injection amount according to the present method. Hereinafter, the coke management method will be described with reference to FIG.

① Coke quality index change

Coke quality indexes are typically managed by DI, CRI and CSR, and are targeted to two or more types of coke with such quality index changes.

② Setting of operating conditions

Considering the blast furnace of the object to be estimated, establish operating conditions that may affect the coke differentiation. That is, the operating conditions such as the amount of pulverized coal injection or the production amount are set.

③ setting of furnace gas composition, temperature distribution and charge drop rate;

Set the gas composition and temperature distribution as the operating conditions change. The setting method may be theoretically possible, but it is preferable to use the vertical sonde measurement equipment as a reference for the measured result. In addition, the rate of descent in the blast furnace of the charge varies with the operating conditions. In other words, when the production volume is large, the charging speed is increased accordingly, and thus the dropping speed of the charge in the blast furnace is also increased. In addition, when the amount of pulverized coal injection increases, the dropping speed of the charged material decreases even in the same production amount. It is preferable that such a load drop speed is also based on the result measured using the measurement equipment.

④ Setting of simulation experiment conditions

Based on the physicochemical situation in which the coke set in steps ① to ③ is received in the blast furnace and the quality of the coke charged at this time, the experimental conditions for simulating the behavior of the coke in the blast furnace are set.

⑤ Coke differentiation simulation experiment

A simulation test is performed on the differentiation behavior of the coke blast furnace under the experimental conditions set in step ④ above. The test apparatus should be configured to simulate, as far as possible, the coke behavior in the blast furnace under similar conditions.

⑥ Measurement of coke differentiation

After the experiment of step ⑤, measure the degree of differentiation of coke. The degree of differentiation is based on changes in coke weight, particle size, and powder generation during the course of the experiment.

⑦ Coke quality control standard setting

In consideration of the change of various operating conditions for one kind of coke quality, a simulation experiment is carried out for the differentiation characteristics according to the procedure of ② to ⑥ above, and the differentiation characteristics of the coke different from the blast furnace operation change for the same quality coke are summarized. do. In the same way, differentiation of coke samples with different quality is carried out in the order of ① ~ ⑥ to simulate the coke differentiation characteristics. As a result of the changes in the coke quality and operating conditions, the result of the change of the coke differentiation characteristics in the blast furnace is derived from an appropriate analysis method such as correlation analysis. Through this relation, it is possible to estimate the quality index of coke to be charged in order to keep the air permeability and liquidity constant in the furnace in the case of changing operation conditions such as the change of coal dust injection.

As described above, if the differentiation characteristics of the coke in the blast furnace is set in advance according to the quality of the charged coke and the change in the blast furnace operating conditions, the quality index of the charged coke can be easily calculated according to the change in the blast furnace operating conditions such as the change in the amount of pulverized coal.

Hereinafter, the method for setting the coke management criteria according to the present method will be described in detail with reference to the following examples.

EXAMPLE

Through this example, the blast furnace having an internal volume of 3800 (m 2) was targeted. The embodiment according to the flowchart shown in FIG. 2 will be described in detail.

① Coke quality change

The quality of the coke used through the examples was shown by comparing the typical quality in Table 1 in the following two types. As can be seen from the table, the quality of the sample coke was chosen to have a relatively large difference.

② Setting of operating conditions

Only the change in the pulverized coal injection amount was considered as a change in the operating conditions considered in this embodiment. The case where no pulverized coal was blown at all and the situation which changed the pulverized coal injection amount into 50, 100, 150, and 200 (kg / ton-melt | melt) were set.

③ setting of furnace gas composition, temperature distribution and charge drop rate;

Using the vertical sonde, the change trend of the situation was measured several times as pulverized coal injection changed, and the change tendency was quantified. As a result of the measurement, the changes in the gas composition and the temperature distribution in the furnace did not appear clearly as the amount of pulverized coal injection changed. Table 2 simplifies the results for convenience of calculation. In other words, the gas and temperature distribution in the furnace furnace direction is a heat preservation zone where the temperature is maintained at 1000 ° C. from 10 to 20 (m) from the surface of the charge, and the gas composition is 12 , Co is 32 Is assumed. In addition, the temperature and gas composition above and below such a heat storage zone change linearly. The temperature and gas composition at the top were assumed to be the same as those at the charge surface.

On the other hand, as the amount of pulverized coal blown in the actual blast furnace operation described above increased, the charge drop rate decreased, and the change amount of the charge drop rate according to the change in the amount of pulverized coal satisfied the following equation.

Where v _d is the charge drop rate (m / min) and PCR is the change in pulverized coal injection (kg / ton-melt).

As described above, in the present embodiment, the change in the furnace situation according to the change of the operation was measured using a measuring device, and the result was quantified according to the change of the operation.

④ Setting of simulation experiment conditions

The change in the furnace condition according to the pulverized coal injection amount was set, and the differentiation behavior of the coke was simulated using the coke rotation differentiation test apparatus.

Based on the above furnace temperature and gas composition analysis and descent rate, the simulated experimental conditions of the pulverized coal injection amount are shown in FIG. 3.

Table 3 compares the temperature at each position in the actual blast furnace set in step (3) described above, the distribution of gas composition, the residence time of the coke and the experimental conditions in the present example which simulated this.

⑤ Coke differentiation simulation experiment

The differentiation of coke in the blast furnace is largely due to chemical reactions and physical friction. In order to simulate the situation close to the coke's blast furnace behavior, an experimental apparatus was devised to rotate the reaction tube 13 at a constant speed so that the physical culture and the chemical reaction proceed simultaneously. 4, the schematic diagram of the rotation differentiation experiment apparatus used by the present Example was shown. The coke sample was rotated in a container 12 having a predetermined shape. For this purpose, four wings in the circumferential direction were attached to the reaction tube 13 in the longitudinal direction. At this time, the driving force of the motor 17 was rotated at a constant speed through the chain 18, the reaction tube 13 was maintained at a constant temperature by the heat generating portion (14). During the reaction, the mixed gas was introduced (15) at a constant rate and the gas was discharged (16) after the reaction. The particle size of the sample coke used in the simulation experiment was based on 20 (mm), and the loading amount was 200 (g).

⑥ Measurement of coke differentiation

FIG. 5 shows the results of measuring the differentiation characteristics of three kinds of coke samples under simulated experimental conditions up to 200 (kg / t-melt molten iron). The Coke Degradation Index (CDI) represents the weight ratio of coke 10 or more (mm) of coke after the reaction to the weight of coke before the reaction charged into the simulation apparatus.

As the amount of pulverized coal blown increased, the residence time of coke in the furnace increased, and thus the CDI tended to decrease. Also, as the amount of pulverized coal blown increased, the amount of coke eruption accelerated. The results obtained from the correlations of the regression analysis of the experimental results using the three types of samples by the least-squares method are shown as solid lines. The correlations are as follows.

Here, the subscripts A20, A23 and B20 mean 20 (mm) coke sample A, 23 (mm) coke sample A and 20 (mm) coke sample B, respectively. At this time, the correlation coefficients of the correlations of the formulas (2) to (4) were all 0.9 or more.

⑦ Setting Coke Management Standard

In FIG. 6, the result of having calculated the change of the average particle size after a rotation differentiation experiment is shown. At this time, the coke particles before and after the test were spherical, and it was calculated using the following relationship assuming that all particles were evenly differentiated.

Where MD ₁ is the average particle size (mm) of the sample before the experiment, and MD ₂ is the calculated average particle size (mm) of the sample after the rotation differentiation experiment. In the results of this simulation, we tried to evaluate the differentiation characteristics of coke based on the CDI, the differentiation index.

The solid line in FIG. 7 is obtained from a correlation of regression analysis of the experimental results. The correlation is as follows.

Using the CDI measurement results of the samples of the same particle size A and B, the CDI, which is the quality and differentiation characteristics of the two samples, is assumed to change linearly, and then the coke quality control index, CSR, DI, and the differentiation characteristics index according to the change of the particle size Changes in the CDI can be interpolated or extrapolated according to the change in the amount of pulverized coal injection. In other words, using the results of this simulation, based on the CDI of 20mm particle size of A sample, the CDI according to the change of coke quality and particle size can be calculated as follows.

Here, the subscript _X means coke of arbitrary quality and particle size, and base means the reference particle size of the charged particle size. Q represents the coke management index such as DI and CSR. Equation (9) is summarized below for representative CSR and DI among the coke quality as shown in Table 1.

If there is no change in the particle size of the charged coke using the formulas (10) and (11), the CSR is 60 to 74. To increase the change in CDI, the differentiation index according to the amount of pulverized coal blown, and the DI to 80 ~ 90 In case of change, it is shown in FIG. 7 and 8 according to the amount of pulverized coal injection.

9 shows the coke quality of the sample coke A, when the particle size of the charged coke is increased to 46 to 56 (mm) under a constant condition.

According to the examples, the equation for calculating the coke differentiation index CDI in the blast furnace according to the change in the amount of pulverized coal and the coke quality charged therein, and the method for preparing the related charts 7 to 9 using the same are shown through the examples. . Through the above examples, in order to verify the adequacy of relations and related diagrams, which can easily calculate and manage the coke quality to be charged according to the operation change, such as the proposed change of coal dust injection, the air blast in the above-described capacity of the actual blast furnace is examined. Through the results of analyzing the sample collected by using a coke sampler (Coke Sampler) that can collect and analyze the contents of the furnace through the results of this example was compared with the results of this example.

In FIG. 10, CDI calculated using equation (10), which is a relational equation which can calculate the coke differentiation index according to the change of particle size and pulverized coal incorporation, among CSR proposed in the present embodiment. This is the change in furnace depth measured in the furnace. As can be seen from the figure, the depth of the combustion zone increases as the CDI increases, i.e. under the condition that the coke is less differentiated. This means that the depth of the combustion zone is increased under the condition that the amount of fine coal injection which is less coke is differentiated and the quality of the charged coke is good. In other words, the lower the coke, the more the zone will increase in depth and thus the less aeration resistance as it passes through the zone, making it an advantageous condition for blast furnace operation. The relationship between the coke differentiation index CDI and the airflow resistance index is shown in FIG. For example, if it is necessary to maintain the furnace depth at 1.7 (m) in FIG. 10 and the in-vehicle insulation resistance index at 2.9 in FIG. 11, the correlations such as Eq. (10) and (11) are required. The CDI value, the coke differentiation index calculated from the relational equation, is about 81 Becomes Ie coke quality CDI 81 Assuming that it needs to be managed so that it can be maintained, the quality of coke to be charged can be derived from Eqs. (10) and (11) or from 7 to 9 degrees. For example, when operating blast furnaces that increase the pulverized coal injection to 100 (kg / t-melt) from Eq. (11) or 8, CDI is 81. If the particle size of the coke to be charged is constant, the DI of coke is 85.2 From 89.5 It means that it should be increased by charging.

As described above, according to the present invention, it is possible to easily set and manage the quality of coke to be charged into the blast furnace in accordance with the change in the blast furnace operation, such as the change in the amount of pulverized coal injection according to the preset criteria.

Claims (1)

Deriving the relationship in which the gas composition and temperature distribution in the furnace and the dropping rate of the charge can be set in advance according to the change in the blast furnace operating conditions such as the change in the amount of pulverized coal injection, and the quality according to the step (1,2) Simulation of the different coke blast furnace differentiation characteristics (4,5) and the simulation experiments (4,5) can be used to calculate the coke differentiation index in the blast furnace according to the change in the pulverized coal injection and the coke quality change. A step (6) of creating a relational equation and a diagram, and a step (7) of setting an appropriate coke quality to be charged into the blast furnace when the pulverized coal injection amount changes by using the relational equation and the chart prepared in the step (6). A method of managing coke according to a change in the amount of pulverized coal injection.