KR100931166B1 - Ventilation control method in blast furnace - Google Patents

Abstract

The present invention relates to a blast furnace control method that can improve the ventilation in the blast furnace by analyzing the change in the air permeability of the blast furnace, so that the blast furnace operation can be performed stably.

According to the present invention, a load measuring device using a load cell is mounted on the rear end of the tuyere probe to detect a load when the lance is moved forward. It provides a ventilation control method in the blast furnace to determine the, the load measurement value and the lance entry speed in real time to determine the breathable bad zone in the furnace, and to control the blowing energy in the optimum range according to the strength of the coke charged.

According to the present invention, it is possible to precisely estimate the structure of the core packed layer according to the fluctuation of the blowing conditions by using the coke sampling lance through the tuyere, thereby selecting an appropriate tuyere diameter for good ventilation. In addition, by controlling the blowing energy in the optimum range in accordance with the strength of the coke to be charged, there is an effect such as to improve the ventilation in the blast furnace, stabilize the blast furnace operation.

Blast furnace ventilation, ventilation control method, probe lance, load measuring device, displacement measuring device

Description

A CONTROL METHOD OF PERMEABILITY OF LOWER PART IN BLAST FURNACE

1 is an explanatory diagram showing a coke charging structure of a blast furnace according to the prior art;

2 is an explanatory diagram showing the structure of a probe lance to be applied in the present invention;

3 is a graph showing the change of the core state of charge according to the distance from the wind hole obtained in the ventilation control method in the blast furnace of the present invention;

4 is a diagram showing changes in gas flow rate and gas flow rate at the tip of the tuyere according to the wind diameter obtained in the ventilation control method in the blast furnace of the present invention;

A) b) of FIG. 5 is a graph showing the change in the airflow resistance index according to the change in the blowing energy obtained in the ventilation control method in the blast furnace of the present invention.

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

10 .... Tuyere Probe

12 ... Lance 20 ... Load measurement device

30 .... Displacement Measurement Device 40 .... Notebook Computer

100 ... blast furnace 103 ... ore

105 ... Coke 107 ... Charter

108 ... slag 110 ... exit                 

112 ... Blowhole 120 ... Burning zone

130 ... Core

The present invention relates to a blast furnace operation method for improving the air permeability of the bottom of the blast furnace, and more specifically, by analyzing the structural change of the core packed bed according to the change in the blowing conditions, and analyzing the air permeability change of the actual blast furnace, The present invention relates to a method for controlling ventilation in a blast furnace that can be improved and, accordingly, enables stable operation of the blast furnace.

In the steel industry, the blast furnace is a high-temperature, high-pressure reactor for producing molten iron by reducing the iron ore charged from the top of the furnace by hot air supplied from the bottom.

1 shows the filling structure under the blast furnace 100, the furnace interior is filled with ore 103 and coke 105, the molten iron 107 and the slag 108 through the air gap between the coke 105 ) Is dropped into the outside of the furnace through the outlet 110. Hot air of about 1200 ° C. and 5 atmospheres introduced through the tuyere 112 forms a cavity at the tip of the tuyere 112 and generates reducing gas. This combustion space is referred to as the combustion zone 120 and the tip of the tuyere 112. The distance from the end of the combustion zone 120 to the combustion zone 120 is defined as the depth of the combustion zone 120.

The combustion zone 120 is a factor that is important in operation as a reaction field that governs the heat and gas supply to the blast furnace 100. And, the coke 105 filling layer located closer to the furnace center than the combustion zone 120 is commonly referred to as the coke layer (or core) of the core 130.

In general, the molten iron 107 and the slag 108 are known to be dripped most of the area within 1 to 2.5 m in front of the tuyere 112, so the coke 105 filled state of the core 130 at this portion prevents melt discharge. This is an important factor.

The molten iron 107 and slag 108 melted and dripped at the fusion zone 132 inside the blast furnace 100 are discharged to the outlet 110 through the coke 105 packed bed, and to the tuyere 112. The supplied high temperature hot air also passes through the core 130 packed bed and is discharged to the top.

If the coke layer of the core 130 is lowered due to the unburned pulverized coal or the differentiated coke 105, the amount of passage of the hot gas into the core 130 is reduced, thereby lowering the core 130 temperature. It causes unstable operation such as delay in departure due to deterioration of melt fluidity.

Therefore, in order to perform stable blast furnace 100 operation, it is essential to accurately determine the state of charge of the coke 105 layer of the core 130 and take appropriate operation measures to maintain good ventilation.

Sonde equipped with a thrust measuring device from the Bosch part of the upper part of the tuyere 112 to the upper portion of the combustion zone 120 during operation of the blast furnace 100 to grasp the coke 105 layer structure of the core 130. ) Is described in Japanese Patent Laid-Open No. 10-192122.

However, this method is difficult to analyze the radial state of charge because the sonde is inserted in the inclined direction, and since the coke 105 of the core 130 cannot be collected, the accuracy through feedback of the actual result is obtained. Difficult to improve Therefore, in an actual operation, an operation method of increasing the blowing flow rate may be used for the purpose of increasing the temperature of the coke 105 layer of the core 130 to increase breathability.

This method is a method performed to increase the depth of the combustion zone 120 by increasing the blowing energy, to increase the amount of heat transfer to the core (130). However, this method has an effect when the strength of the level coke 105 of the tuyere 112 is large enough to withstand the increased blowing energy, but when it is not, the coke by activation of the turning motion of the coke 105 is rather effective. 105) Differentiation is promoted to increase the amount of generated coke 105. Therefore, contrary to the original intention, the air permeability of the hot gas is lowered, resulting in destabilization of operation.

On the other hand, as another conventional operation method, as shown in Japanese Patent Laid-Open No. 2000-192122, the shape of the inner surface of the tuyere 112 is adapted to shrink-enlarge to adjust the inner ratio of the contraction-enlarged portion. It is reported that the shape control and the pressure loss of the combustion zone 120 can be reduced by this. Although this method is a new attempt, the effect of increasing the depth of the combustion zone 120 is insignificant, and the shape of the tuyere 112 is complicated, which makes it difficult to manufacture.

The present invention is to solve the above conventional problems, the purpose is to improve the ventilation in the blast furnace by analyzing the structural change of the core filling layer according to the change in the blowing conditions, and the change in the air permeability of the actual blast furnace It is to provide a ventilation control method in the blast furnace to derive a plan that can perform the blast furnace operation in a stable manner.

In order to achieve the above object, the present invention is to measure the change in the filling structure of the furnace according to the blowing conditions, and through the correlation analysis of the actual blast furnace ventilation characteristics while maintaining the air permeability good blast furnace in the blast furnace In the breathable control method,

Mounting a load measuring device using a load cell at a rear end of the tuyere probe, and detecting a load transmitted directly to the rear end when the probe lance is advanced;

At the rear end of the probe lance is equipped with a displacement measuring device capable of measuring the displacement by converting the increase and decrease length of the wire drawn out in accordance with the advance of the lance into an electrical signal, and measures the lance entry speed when the probe lance is advanced Step; and

The load measured value from the load measuring device and the lance entry speed are analyzed in real time, and the load measured value is rapidly increased, and the air permeability bad zone is judged from the position where the entry speed is rapidly reduced and blown according to the strength of the coke charged. By controlling the energy in the optimum range; by providing a ventilation control method in the blast furnace comprising a.

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

Ventilation control method in the blast furnace according to the present invention analyzes the lance entry speed in real time to increase the load measurement value, and determine the ventilation area in the furnace from the position where the entry speed decreases rapidly blown energy in accordance with the strength of the coke charged By controlling the to an optimum range, it is possible to improve the ventilation in the blast furnace and to stabilize the blast furnace operation.                     

2 is a schematic diagram of the tuyere probe 10 used in the present invention, while performing the conventional coke 105 sampling function, the lance 12 of the tuyere probe 10 so as to analyze the filling structure in the furnace. A load measuring device 20 using a load cell is mounted at the rear end, and a displacement measuring device 30 capable of measuring the insertion length of the lance 12 is provided.

In the above, the load cell has a hollow cylindrical structure, and is capable of directly receiving the force applied to the rear end of the sampling lance 12 and is designed to withstand a load of up to 20 tons.

In addition, the displacement measuring device 30 provided at the rear end of the lance 12 may measure the displacement by converting the increase and decrease length of the wire drawn out according to the advancement of the lance 12 into an electrical signal, and measure the maximum measurement. The distance is 5.6m. The measured force and displacement values are converted into digital signals through an A / D converter (not shown) and stored in the notebook computer 40 in real time.

And, according to the present invention by using the load measuring device 20 mounted to the rear end of the lance 12 of the tuyere probe 10, detecting the load transmitted directly to the rear end when the probe lance 12 is advanced Is done. At the same time, through the displacement measuring device 30 provided at the rear end of the probe lance 12, the length of the wire drawn out in accordance with the advance of the lance 12 is converted into an electrical signal, so that the lance at the time of the advance of the probe lance 12 is transformed. (12) The step of measuring the entry speed is made.

As such, according to the analysis results of the tuyere probe 10 during the blast furnace 100 according to the present invention, the coke 105 in the lower part of the blast furnace 100 is less dense in the combustion zone 120 region, From the point where the combustion zone 120 ends and the core 130 starts, the powder begins to accumulate and becomes dense.

Therefore, when the lance 12 is inserted from the tip of the tuyere 112, the load value applied to the lance 12 is small due to the low insertion resistance when passing through the combustion zone 120 region, and thus the core 130 is formed. The load value starts to rise from the point when it reaches.

In addition, if the propulsion force for pushing the lance 12 is made constant, the entry speed of the lance 12 is fast because the insertion resistance is small in the combustion zone 120, and starts to slow down from the point of contact with an area with a dense state of charge. . Therefore, the state of the core 130 can be determined by measuring the change in the force applied to the lance 12 and the insertion speed of the lance 12.

When the measurement of the load and the forward speed of the lance is completed as described above, the load measurement value and the lance entry speed are analyzed in real time to determine that the load measurement value is rapidly increased, and to determine a poor ventilation area in the furnace from the position at which the entry speed decreases. The blowing energy is controlled to an optimum range according to the strength of the coke charged.

Meanwhile, the present invention analyzes the load measurement value from the load measuring device 20 and the entry speed of the lance 12 in real time, so that the load measurement value increases rapidly and the in-vehicle breathability bad zone from the position where the entry speed decreases rapidly. Determining and further comprising the step of selecting and installing the optimum tuyere 112 diameter.

3 shows the change in the instantaneous entry speed (dx / dt) of the lance 12 when sampling the blast furnace coke 105 according to the invention according to the distance from the tuyere 112.

Here, one tuyere 112 has a diameter of 120mm, the other tuyere 112 is 130mm in the case of a change in the entry speed of each other can be seen to be significantly different.

Where the 130Φ blowhole 112 is used in the place where the lance 12 has entered the depth up to about 3.5m, the entry speed is also relatively high, while when using the 120Φ blowhole 112 the depth of entry of the lance 12 is also about Only about 2.8m was entered, and from about 1m or more, the entry speed of the lance 12 can be seen to decrease rapidly.

This means that the core 130 coke layer in the front part is very dense when the 120Φ air vent 112 is used, and therefore, it can be expected that the gas breathability will be very poor under such conditions.

FIG. 4 shows the gas flow rate and the gas flow rate passing through the tip of the tuyere 112 for the blast furnace 100 in operation by mixing 120Φ and 130Φ tuyeres 112 in order to verify the result shown in FIG. I got it.

Although the detected gas flow rate is calculated at the same level in both cases, it can be seen that the gas flow rate is about 14% less than that of the 120Φ air vent 112. This is a phenomenon that occurs due to the characteristics of the fluid to be preferentially drawn through the 130Φ blowhole 112 that takes less pressure resistance than passing through 120Φ blowhole 112, which is a high pressure resistance when the gas passes through the blowhole 112.

On the other hand, the structure of the core 130 filling layer in the blast furnace 100 depends largely on the blowing energy. The blowing energy is an item calculated as mv ² /(2×9.8), where m is the gas mass and v is the gas flow rate.

Comparing the blowing energy in the case of the 120 Φ to 130 Φ air vent 112, it can be seen that the blowing energy is about 13% less in the case of 120 Φ. As a result, the depth itself of the combustion zone 120 is shortened, and the amount of heat transfer to the center of the furnace is reduced, and it is interpreted that the air permeability / permeability decreases while the temperature decreases.

Therefore, the state of filling the core 130 is periodically determined by measuring the entry speed of the lance 12, and a vent hole 112 having an appropriate diameter is installed for each circumferential direction to optimally manage the blowing energy to maintain good ventilation. shall.

5 is a drawing of the ventilation resistance index in the blast furnace 100 according to the change in the blowing energy. The ventilation resistance index is calculated as (blow pressure ² -nominal pressure ² ) / (bosch gas amount) ^1.7 , where the pressure is absolute pressure and the unit is g / cm 2 and the unit of bosch gas amount is Nm 3 / min. In other words, the high airflow resistance index means that the pressure loss is high in the blast furnace 100 and the airflow is bad.

In order to maintain the ventilation in the furnace, it was explained that the blowing energy should be properly maintained. In the background of this, if the strength of the coke 105 charged in the furnace is high, the ventilation energy in the furnace can be improved by increasing the blowing energy and increasing the amount of gas passing through the furnace and the heat transfer, whereas the strength of the furnace coke 105 is increased. If it is low, it is because the differentiation of the coke 105 is promoted by the increase of the blowing energy, rather the phenomenon that the air permeability may deteriorate.

Therefore, it can be predicted that the management range of the blowing energy should be different according to the strength of the charging coke 105. When the cold strength DI of the charging coke 105 is 87.3 or more, as shown in FIG. 5A, it can be seen that air permeability is improved by increasing the blowing energy. Therefore, by maintaining the cold strength (DI) of the charging coke 105 to be charged into the blast furnace 100 to 87.3 or more, and controlling the blowing energy in the range of 12000 ~ 13000kg · m / s, good ventilation of the furnace is maintained And the molten iron 107 will be able to stably increase the production.

However, if the cold strength (DI) is shown in Figure 5b) 87.3 or less, it can be seen that the air permeability slightly decreases as the blowing energy increases. Therefore, after inspecting the strength of the charged coke 105, and operating in the range of blowing energy according to it, it is possible to stably produce the molten iron 107 while maintaining good breathability.

As described above, according to the present invention, it is possible to accurately estimate the structure of the core 130 packed bed according to the fluctuation of the blowing conditions using the coke sampling lance 12 through the tuyere, thereby providing a good ventilation The aperture 112 may be selected.

In addition, by controlling the blowing energy in the optimum range according to the strength of the coke 105 is charged, there is an effect such as to improve the ventilation in the blast furnace 100, stabilize the operation of the blast furnace 100.

Claims (3)

In the blast furnace air permeability control method that can measure the change in the filling structure of the furnace according to the blowing conditions and maintain the air permeability while maintaining a good ventilation through the correlation analysis with the actual blast furnace air permeability, Mounting a load measuring device (20) using a load cell at a rear end of the lance (12) of the tuyere probe (10), and detecting a load transmitted directly to the rear end when the probe lance (12) is advanced; At the rear end of the probe lance 12 is equipped with a displacement measuring device 30 that can measure the displacement by converting the increase and decrease length of the wire drawn out in accordance with the advance of the lance 12 into an electrical signal, the probe lance ( Measuring the rate of entry of the lance 12 upon advancing 12); and The load measurement value and load lance 12 from the load measuring device 20 are analyzed in real time, and the load measurement value is rapidly increased, and the air permeability defective zone is charged from the position where the entry speed is rapidly reduced. And controlling the blowing energy to an optimum range according to the strength of the coke. After measuring the entry speed of the probe lance 12, the load measurement value from the load measuring device 20 and the entry speed of the lance 12 are analyzed in real time to increase the load measurement value and the entry speed decreases rapidly. The air permeability control method of the blast furnace further comprises the step of selecting and installing the optimum air hole (112) diameter by determining the in-vehicle ventilation poor zone. delete According to claim 1, The step of controlling the blowing energy in the optimum range according to the strength of the coke is to manage the cold strength (DI) of the charging coke 105 charged to the blast furnace 100 to 87.3 ~ 100% And controlling the blowing energy in the range of 12000 to 13000 kg · m / s, thereby maintaining the furnace air permeability and stably increasing the amount of molten iron.

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