KR20010054885A - A method of judging a inactivity index and flowage at the lower part of blast furnace - Google Patents

Abstract

PURPOSE: A method for judging fluid permeability and inactivity index of the lower part of a blast furnace is provided to maintain stable operating conditions of the blast furnace by estimating a particle diameter of coke in the center of the blast furnace which is an index of the inactivity and fluid permeability of the lower part of the blast furnace so as to take a measure for improving quality of coke when the particle diameter of coke is decreased for a long period of time. CONSTITUTION: The method comprises a first step of detecting average particle diameter of charged coke, cold strength of charged coke, hot strength of charged coke and pulverized coal injection amount respectively; a second step of obtaining an average coke particle diameter at the tuyere level based on the average particle diameter of charged coke, cold strength of charged coke, hot strength of charged coke and pulverized coal injection amount detected in the first step; and a third step of judging fluid permeability and inactivity index by the average coke particle diameter at the tuyere level obtained in the second step.

Description

A method of judging a inactivity index and flowage at the lower part of blast furnace}

The present invention relates to a method for judging the liquid permeability and inertness of the bottom of the blast furnace, and particularly for estimating the core coke particle index, which is an indicator of inactivation and liquid permeability of the bottom of the blast furnace, when the coke particle size is lowered for a long time, The present invention relates to a method for determining the liquidity and inertness of the bottom of the blast furnace that can maintain a stable aging state by taking measures.

1 is a view showing a general blast furnace and peripheral equipment, Figure 2 is a view showing the internal situation during the operation of the blast furnace, generally blast furnace operation is economical operation is possible only if the ventilation and liquidity of the bottom of the blast furnace (1) is maintained. In addition, this can not only increase production, but also extend the life of the blast furnace in the long run.

However, in recent years, blast furnaces have increased the use of relatively inexpensive pulverized coal instead of expensive coke for economical operations, while increasing production at blast furnaces contributes to the economic operation of post-processes. In addition, there are problems such as uneconomic operation and fluctuation in charter quality due to unstable instability and charter temperature deviation.

The blast furnace is a high-temperature, high-pressure reactor for producing molten iron by reducing and melting iron ore and coke charged from the upper side by hot air supplied through the tuyere (1-2). In Gwangyang Blast Furnace, the temperature of molten iron (1-3) is controlled to 1510 ± 10 ℃. Sometimes, some of the molten iron temperature fluctuations are higher or lower than the other molten iron (3-3). This may occur. Once such a molten iron temperature is uneven, it takes a long time to recover, and in some cases even stops the blast furnace operation. At this time, when the temperature difference of molten iron occurs, the furnace rise measures are taken to raise the molten iron temperature based on the exit port that recorded the lowest molten iron temperature. However, this method may adversely affect the blast furnace operation by increasing the fuel cost of the blast furnace to increase the cost of the charter, and also to increase the overall heat level of the heart to promote low smoke and erosion.

Gwangyang Blast Furnace is operating high-exposure ratio and high PCR-oriented operation. In the case of high ship run operation, the level of melt in the furnace rises, and in the case of high PCR operation, unburned coal accumulates in the core, and the liquidity of the melt in the core deteriorates. Therefore, there is a need for derivation of control measures to resolve the temperature deviation of each exit port during operation and to secure good fluidity of the lower part.

In general, the blast furnace operation transfers the ore and sintered ore extracted from the raw material bins 6-4 and 6-5 to the top of the blast furnace through the charging belt conveyor 3, as shown in FIG. ) And the hopper upper sealing valve (2-3) to store in the top hopper (2).

Subsequently, coke (grain size: 35 to 55 mm) was charged and opposed sintered ore so as to be uniformly charged and distributed in the blast furnace, which is controlled at a tilt angle for each field set by the turning chute (2-2) that can be charged by particle size. Particle size: 12 to 50 mm) and small sintered ore (particle size: 5 to 12 mm) in the order of charging coke uniformly in the radial direction to ensure stable gas flow in the upper part of the blast furnace to maximize air permeability and gas utilization rate The uniformity of the gas flow of the part and the wall part makes softening fusion zone 1-1.

On the other hand, on the side of the furnace, a small sintered ore (6-3) having excellent reducibility and air permeability is seated to prevent the generation of inert zones of the furnace wall, and the furnace wall is alternately charged at the top of the blast furnace to form a layer. The hot hot air sent from the hot stove facility is blown into the blast furnace through the tuyere (1-2) to cause the reduction and melting of the iron ore, to produce the molten iron (1-3).

In the blast furnace operation, when the operation is started after the initial fire, and normal operation is achieved after about one month, most of the stamping material attached to the side wall part of the exit bottom is extinguished. The operation will begin.

And the molten iron | metal 5-2a and slag 5-2 which exist in the lower part of the blast furnace are four directions of 33 degree | times, 147 degree | times, 213 degree | times, and 327 degree | times at intervals of about 120 minutes by the taping work performed alternately in four directions. The melt is discharged intensively, and the melt produced at the blast furnace and the fusion zone is heated up through the core coke at the bottom of the blast furnace to be discharged to the outside of the furnace. The smaller the particle size of the core coke is, the smaller the amount of melt is mixed in the core coke layer, resulting in extremely poor air permeability and liquid permeability in the core coke particle diameter, thereby making it unacceptable to yellowing instability. Therefore, the particle size of coke charged from the top of the blast furnace during normal operation can be always determined by the data analyzed by the 8-hour cycle, but the core coke is not proportional to the particle size of the coke charged, but the ambient temperature of the coke coke itself at the time The results of coke sampling at the bottom of the blast furnace were found to depend on strength, hot strength, reactivity, and fine coal injection. Therefore, it is important to estimate the core coke particle size during normal operation, and to take prompt measures to improve the coke quality when the coke particle size decreases for a long time.

The prior art which can estimate the core coke particle size of such a blast furnace is as follows.

First, there is a method of estimating the core coke diameter by judging the particle size at the time of blast furnace coke. This method is judged by the logic that large, small and small simply by coke size at the time of charging of the blast furnace. Therefore, the impact factor is not considered at the time of charging, but the strength and reactivity and the pulverized coal injection cost at that time are not considered at all. Has not been a reasonable way to estimate core coke particle size.

Second, there is a method of determining the coke particle size by taking a coke sample with a radial direction in the coke furnace at the location of the blast furnace level at the bottom of the blast furnace during regular blast furnace maintenance, such as a periodical repair performed every 10 weeks, but it is limited to regular repairs. There is a lot of work and material consumption, there is a limit that can not be used in normal operation, it is not a fundamental solution for determining the core coke diameter of the blast furnace in normal operation.

Therefore, in order to determine the coke particle size of the lower blast furnace bottom part more reliably to determine the coke particle size of the lower part of the blast furnace, as a result of the study, as shown in Fig. Coke sampling from the bottom was performed. Based on the results, we developed an estimation formula for the bottom coke diameter determination based on the furnace conditions at that time, the room temperature strength and hot strength of the coke itself, and the reactivity and pulverized coal injection. Coke particle size is estimated and judged during normal operation, and it is managed to manage it by making it an important index so that coke quality improvement can be taken early when the coke particle size decreases for a long time, so as not to reach a large yellowing fault condition called core inactivation. By implementing the method, various problems listed above are solved.

The present invention is to achieve the above object, it is achieved by the method of determining the liquid permeability and inert index of the bottom of the blast furnace to obtain the mouthpiece level average coke particle diameter and indirectly determine the liquid permeability and inert index.

In the method for determining the liquid permeability and inertness index of the lower part of the blast furnace, the first step of detecting the average amount of charged coke, the charged coke cold strength, the charged coke hot strength, and the amount of pulverized coal injection respectively, and the charge detected in the step The second step of obtaining the mouthball level average coke particle size on the basis of the coke average particle diameter, the charged coke cold strength, the charged coke hot strength, and the amount of pulverized coal blown; It is achieved by the method of determining the liquid permeability and inert index of the bottom of the blast furnace, characterized in that it comprises a third step of determining the index.

1 is a view showing a typical blast furnace and peripheral equipment.

2 is a view showing an internal situation during blast furnace operation.

3 is a radial core coke particle size distribution in the radial direction according to the core coke sampling results at the tuyere level.

Figure 4 is a core coke particle size distribution of less than 3mm in the radial direction according to the core coke sampling results.

5 is a view showing the flow of molten iron at the time of generation and disappearance of the molten iron impermeable layer in the blast furnace bottom part.

6 is a graph showing the core coke particle diameter and the molten iron hold-up which are the molten iron impermeable layer forming factors.

<Description of the symbols for the main parts of the drawings>

1: blast furnace 1-1: softening zone

1-2: blowhole 1-3: molten iron

1-4: Charging Baseline 1-5: Block

1-6: Load Position Tracker 1-7: Chain

1-8: Chu 2: Top Hopper

2-1: Light control valve 2-2: Charge turning chute

2-3: Hopper sealing valve 2-4: Transfer chute

3-1: Titanium Ore Loading Area 3-2: Charging Baseline

3-3: Exit 5-2: Slags Stored in Nozer

5-2a: Charterer stored in the furnace 5-3: Core coke layer

5-4: Nozzle and 6: Conveyor Belt

6a: Raw material movement position sensor 6-1: Coke storage hopper

6-2: Sintered Allergy Storage Hopper 6-4: Coke Storage Tank

6-5: Ore Reservoir 6-2a: Opposing Ore Charged in Blast Furnace

6-3a: Small ore charged in the blast furnace

7-1: Center Charged Coke 7-2: Heavy Coke

8-1: molten iron impermeable layer 8-2: nozer slag

8-3: Melt-off Charter 8-4: Stagnation charter layer underneath

9-1: Average particle size of core coke 9-2: Allowance ratio stagnated between core coke

Hereinafter, the present invention will be described with reference to the accompanying drawings.

3 is a radial core coke particle size distribution in the radial direction according to the core coke sampling results at the tuyere level, Figure 4 is a core coke particle size distribution of less than 3mm in the radial direction according to the core coke sampling results, Figure 5 is a blast furnace bottom section It is a figure which shows the flow of the molten iron at the time of formation and annihilation of a molten iron impermeable layer, and FIG. 6 is a figure which shows the core coke particle diameter and molten iron hold-up amount which are a molten iron impermeable layer formation factor.

In order to maintain stable breathability and fluidity at the bottom of the furnace through smooth melt flow and discharge of the bottom of the furnace, which affects the lifetime of the furnace in the furnace, the core coke particle size at the bottom of the blast furnace must be maintained above the management range. Based on the results obtained through coke sampling at several times, the core coke particle size management is carried out every 8 hours during actual operation to maintain breathability and liquid stability through core coke layer maintenance, and to create a charter impermeable layer. The present invention relates to a method for determining core conditions by calculating core coke average particle size estimation equations based on actual industry performance in order to solve the deviation of the molten iron temperature and prevent core inertia through the preliminary prevention.

In the present invention, scientific core state segmentation and core impermeable layer through derivation and application of core particle index estimation equation which enables the core coke particle size to be determined at all times during operation by analyzing the physical properties of windball level coke collected by coke sampling. Through the analysis of fluidity and temperature distribution according to the shape of the filling layer due to the formation, this study aims to discharge the method of maintaining the bottom healthy coke layer and improving the lower liquid permeability.

In addition, in the blast furnace operation in which the opposite ore coke and the small sintered ore are alternately charged from the top of the road to form a layer, which is reduced and melted to produce molten iron, the coke sampling is performed at the bottom of the blast furnace, which has been carried out at the Gwangyang Blast Furnace for seven regular repairs. It was.

Based on the results, we developed an estimation formula for the bottom coke diameter determination, which is highly dependent on the furnace conditions at that time, the room temperature strength and hot strength of the coke itself, and the reactivity and the pulverized coal injection. The core coke particle size is estimated during normal operation. In addition, it should be managed by making an important index so that coke quality improvement can be taken early when the coke particle size decreases for a long time, so as not to reach the large yellowing defect state called core inactivation.

As a technical gist of the method for solving the various problems listed above, the coke loaded as shown in FIG. 2 is judged on the basis of the quality and the particle size, together with the operating opinion, to comprehensively determine the core coke layer 5-3. This study aims to promote economic operation and stabilize the stabilization of old age by using the estimation formula to judge the

In the blast furnace operation, the coke and the sintered ore discharged from the top hopper (2) are charged at 1.0m (3-2) in the normal operation, and are alternately charged by the rotation of the turning chute (2-2) to form a layer. .

Then, when hot coke is blown by blowing hot coke through the tuyere 1-2, a heat source and a reducing gas are generated, and the iron ore is reduced and melted by the heat source and the reducing gas, and finally a soft fusion zone (1-1-). 1) Below, the melt is present.

In order for the blast furnace operation to be performed smoothly, above all, the air permeability and liquid permeability of the blast furnace bottom part are maintained, and in particular, the core state should not reach an inert state. In order to draw, the coke particle size in the core part of the lower part of the tuyere should be maintained to some extent.

As shown in FIG. 3, the average particle diameter change of the coke according to the distance from the tip of the tuyere is drawn. The average particle diameter decreases to about 100cm at the tip of the tuyere. After that, it increases and then decreases in the core side, and the overall average particle diameter changes around 25mm.

As shown in Figure 4 shows the change in the fraction of -3mm in the coke, the -3mm fraction shows a rapidly increasing trend after 200 Cm. This is presumably because the generated coke was scattered to the hearth or the core along with the gas flow and accumulated in the space of 2-3m in front of the tuyere.

In this case, when the coke particle size (5-3) is maintained for a long time with a small degree or more, it shows a high melt ratio, that is, a ratio of molten iron + slag / coke, and a low softening fusion zone (1-1) formation. In the drooping state, the amount of molten material having low fluidity, which is not heated up, is stagnant in the coke layer 5-3 is increased (Fig. 6).

In this case, the molten iron temperature deviation occurs for each column, and the poor liquidity of the coke layer due to the sagging phenomenon of the fusion zone may appear, and the yellowing becomes more and more unstable.

It shows the amount collected in the core coke 5-3 of the melt according to the tuyere level coke particle diameter. Here, the melt retention amount was defined as the weight ratio occupied by the melt (molten iron + slag) in the total contents. As shown in the figure, the smaller the coke particle diameter, the larger the retention amount of the melt, and from this, it can be seen that the liquid permeability of the coke filling layer is poor.

In this study, Equation 1, which is the following estimation equation for coke grain size, was derived through coke particle size and co-factors obtained from coke grains.

Dc = 0.11MS + 2.91DI + 0.82CSR-0.019PCR-290

here,

Dc: Airball level average coke particle size (mm)

MS: Charged coke average particle diameter (mm)

DI: Charged coke cold strength (%)

CSR: charged coke hot strength (%)

PCR: Pulverized coal injection (kg / t-p)

As can be seen from the above equation, the coke particle size of the tuyere level can be seen to increase as the particle size, cold strength, and hot strength of the charged coke increase. Therefore, it is proving that it is important to improve the liquid permeability to secure the appropriate coke particle size at the tuyere level by improving the cold strength and hot strength of the charged coke.

Here, the core coke particle diameter according to the above formula is applied 3 days before, that is, 72 hours before the charged coke properties and particle diameter, 3 days or more (9 data continuous), and 7 days (21 data consecutively) less than 21mm In case of more than 5 days (more than 15 data), the quality of charging coke (6-1a) should be improved immediately and the core coke (5-3) should be reinforced.

Here, when the core coke (5-3) is determined using Equation 1, the reason for limiting the correlation with the charged coke (6-1a) before 72 hours is to derive the correlation. It begins to affect the size of about 72 hours after charging, more than 3 days (more than 9 data) and 21 days or less, and more than 5 days (more than 15 data) of 7 weeks (21 data) ) Is limited to the case.

The present invention estimates the core coke particle size index, which is indicative of inactivation of the blast furnace, and an indicator of air permeability and liquid permeability, and estimates the coke particle index that is accelerated when the coke particle size decreases for a long time. It is important to take measures such as quality improvement at an early stage, so that it can be effective by maintaining a stable yellowing state at all times.

In addition, by allowing the operator to monitor and judge, there is an effect of preventing the core inertness due to the operation of the high pulverized coal and the high shipping cost, as well as the determination of the formation of the low permeability layer of the molten iron as a previous phenomenon. .

Claims (4)

In the method of judging liquid permeability and inertness of the blast furnace, A first step of detecting the charged coke average particle diameter, the charged coke cold strength, the charged coke hot strength, and the pulverized coal injection amount, respectively; A second step of obtaining a mouthball level average coke particle size on the basis of the charged coke average particle diameter, charged coke cold strength, charged coke hot strength, and pulverized coal injection amount detected in the above step; And a third step of determining a liquid permeability and an inert index based on the windball level average coke particle size obtained in the second step. The method of claim 1, The liquid permeability and the inertness index determination method of the lower part of a blast furnace are judged that liquid flow property is judged to be low when the said mouthball level average coke particle diameter is small, and it is determined that fluid flowability will rise when the said mouthball level average coke particle size is large. The method of claim 1, The method for determining the liquid permeability and inertness index of the blast furnace bottom, characterized in that the mouthball level average coke particle diameter is calculated by the following equation (2). <Equation 2> Dc = 0.11MS + 2.91DI + 0.82CSR-0.019PCR-290 here, Dc: Airball level average coke particle size (mm) MS: Charged coke average particle diameter (mm) DI: Charged coke cold strength (%) CSR: charged coke hot strength (%) PCR: Pulverized coal injection (kg / t-p) The method according to claim 1 or 3, The coke particle size and properties applied to Equation (2) is a liquid permeability and inert index determination method of the bottom of the blast furnace, characterized in that the applied coke properties and particle size before 72 hours.