KR20020040505A - Method for managing air velocity of tuyere by coal injection ratio - Google Patents

Abstract

PURPOSE: A method for controlling a flow rate of tuyere according to pulverized coal injection ratio is provided which efficiently performs high pulverized coal operation by gradually increasing the flow rate of the tuyere as the pulverized coal injection ratio is being increased, thereby guiding improvement of blowing energy. CONSTITUTION: The method for controlling a flow rate of tuyere according to pulverized coal injection ratio comprises the steps of determining a pulverized coal injection amount according to production in a blast furnace; reducing a diameter of the tuyere so as to increase the flow rate of the tuyere proportionally to the pulverized coal injection amount by controlling diameters of tuyeres(31) a plurality of which are installed on the outer circumference of the blast furnace after the step of determining the pulverized coal injection amount; and constantly controlling an overall air volume supplied into the blast furnace in the process of performing the step of reducing a diameter of the tuyere by controlling diameters of tuyeres(31), wherein the diameter of the tuyere is controlled by attaching or detaching tuyere rings(32) having various diameters to or from the tuyere in the step of controlling a diameter of the tuyere, and the tuyere rings(32) are symmetrically installed on the plurality of tuyeres(31) around the center of the blast furnace.

Description

How to manage wind speed according to pulverized coal injection cost {METHOD FOR MANAGING AIR VELOCITY OF TUYERE BY COAL INJECTION RATIO}

The present invention relates to a method for managing the wind tunnel flow rate according to the coal dust injection rate to efficiently carry out the high pulverized coal operation by increasing the wind tunnel flow rate step by step when increasing the coal dust injection rate.

As shown in FIG. 1, fuels charged during pulverized coal operation in blast furnace operations include coke (1) and pulverized coal (2). Coke (1) is charged in a lumped state and plays an important role in maintaining breathability in the blast furnace. I am in charge.

However, coke 1 has been replaced by pulverized coal recently because of its high cost and complicated manufacturing process.

Since the pulverized coal is blown into the blast furnace in powder (powder) state, as the amount of blowing increases, the coke (1) is relatively reduced, resulting in deterioration of air permeability, increase in wind pressure, and unstable yellowing.

Conventionally, in order to prevent such an increase in wind pressure, as the pulverized coal injection ratio increases, an operating method of keeping the wind hole flow rate constant or slightly increasing the wind pressure rises is suppressed.

If the pulverized coal injection ratio is drastically increased, a large amount of pulverized coal is injected into the furnace, and thus the combustibility is lowered and the coal is not burned in the furnace, and the sediment layer 3 is particularly distributed around the tuyere.

This is called a bird nest (4) and forms a hard layer that can not penetrate the blowing energy (5).

Therefore, since the amount of air blown in from the tuyere does not penetrate smoothly to the center of the furnace, the blowing energy cannot be effectively transmitted to the hearth of the core, thereby lowering the temperature of the core 6, which brings about a temperature decrease of the tuyere tip 7, thereby pulverizing coal dust. When a large amount of blowing is caused, the combustibility is remarkably lowered due to the decrease in the ambient temperature.

In addition, the injected pulverized coal is not efficiently burned and is deposited 3 on the wall around the tuyere, resulting in a furnace wall heat load.

In order to solve this problem, it is necessary to increase the molten iron temperature (8) or to increase the oxygen enrichment amount to increase the tuft tip temperature (7) or to physically destroy the bird nest during the blast furnace airflow. As it bears the cost increase due to the increase in fuel cost and oxygen increase, it is not preferable and adversely affects the aging.

The present invention has been made in view of the above-mentioned problems in the prior art, and while increasing the pulverized coal injection ratio, at the same time increasing the windball flow rate proportionately, effectively removing the bird nest at the tip of the windball and cored blowing energy. Its purpose is to provide airflow flow rate management method according to the pulverized coal injection ratio, which efficiently delivers the core temperature to secure core temperature, secure the combustibility of pulverized coal and control the furnace wall heat load efficiently.

The above object of the present invention comprises the steps of determining the amount of pulverized coal blown according to the output amount to be produced in the blast furnace; Reducing the diameter of the balloon to increase the flow velocity of the balloon in proportion to the amount of pulverized coal by adjusting the balloon diameter of each of the balloon holes installed in the outer periphery of the blast furnace after the step; In the course of performing the above steps, the overall air volume supplied to the blast furnace is achieved by including a step of adjusting to be constant.

1 is a schematic diagram showing the internal furnace conditions during the operation of pulverized coal in a typical blast furnace operation,

2 is a perspective view of the tuyere and tuyere ring according to an embodiment of the present invention,

3 is a perspective view showing a test apparatus for implementing the present invention,

Figure 4 is a graph showing the wind flow velocity criteria according to the pulverized coal ratio established in the present invention.

Explanation of symbols on the main parts of the drawings

1: coke, 2: pulverized coal,

31: airball, 32: airball ring,

42: pipe, 42,44: records.

Hereinafter, a preferred embodiment according to the present invention will be described in more detail on the basis of the accompanying drawings.

Figure 2 illustrates a balloon opening and a balloon opening for increasing the diameter of the tuyere in order to achieve the management method according to the present invention.

According to Figure 2, it is mounted to the tuyere 31 is provided with tuyere ring 32 for efficiently increasing the tuyere flow rate.

The tuyere ring 32 is a truncated cone-shaped hollow inside, the diameter of one end is formed narrower than the diameter of the other end, the narrowly formed portion is inserted and fixed toward the front end side of the tuyere 31.

In addition, the tuyere ring 32 is preferably formed of a copper material.

As such, the reason for using the tuyere ring 32 is to increase the flow rate of hot wind through the tuyere by reducing and adjusting the tuyere diameter of the tuyere 31.

That is, in the present invention, the above-mentioned conventional problems can be solved by performing the operation by reducing the bulge diameter by increasing the bulge diameter as the blowing ratio increases.

Of course, it is possible to adjust the diameter of the tuyere 31 itself without using the tuyere ring 32, but this is not cost effective, manufacturing.

The flow velocity of the tuyere should be increased in proportion to the blowing ratio of the pulverized coal, which can be calculated by the experimental value and can be easily adjusted through the variable diameter of the tuyere ring (32).

Therefore, the tuyere ring 32 may have a variety of diameters and shapes according to the operating conditions, the pulverized coal injection ratio through the bird nest depth measurement recorder 42 and the core temperature measurement recorder 44 as shown in FIG. The proper wind speed can be determined according to

In this case, when adjusting the wind diameter to increase the wind flow velocity, the air flow rate should be maintained at the same level to prevent operation variables caused by other factors.

The air flow velocity can be calculated by Equation 1 below, and the influence factors are factors such as air volume, air pressure, oxygen, humidity, wind temperature, and wind diameter factors. In addition, there are factors that change fuel costs, such as increase and decrease of fuel costs.

It is most efficient to reduce the wind diameter in order to increase the flow velocity with the same air volume, wind temperature, oxygen and humidity.

Therefore, except for the adjustment of the diameter, all the means act as a variable in the operation, in the present invention, the method for increasing the flow rate of the wind through the diameter adjustment.

[Equation 1]

Appropriate windball flow rate according to the pulverized coal injection ratio applied to the present invention was determined through the results of the test operation, and as a result of the test operation, the same result as the birdest thickness measurement (hereinafter referred to as "raceway depth") at the rise of the windball flow rate, the core temperature measurement result , Furnace bottom temperature measurement results, furnace wall heat load measurement results, and fuel ratio comparison, which is a measure of combustibility, are possible.

EXAMPLE

In the present invention, a balloon ring was used in order to reduce the balloon diameter, and a balloon diameter ring having a thickness of 10 mm was inserted into the inner surface of the balloon diameter of 140 mm to reduce the balloon diameter to 120 mm, thereby reducing the overall diameter.

In addition, according to Equation 1, when the air flow rate was kept the same, it was found that the air flow velocity increased by 1.2% when the wind diameter decreased by 1%.

The result of the test operation by reducing the wind diameter as described above is as follows.

As shown in FIG. 3, a device for measuring the bird nest thickness 43 by inserting the pipe 41 through the tuyere and attaching a recorder 42 for changing the difference in thrust into a current signal was used. In other words, the greater the raceway depth, the more combustible operation results were obtained without the formation of a layer around the wind hole when the pulverized coal increased.

In addition, a pipe was attached to the tip of the thermometer to measure the temperature of the raceway tip, that is, the core part (44) was attached to the operation of the airflow flow rate was confirmed that the result of the core temperature rises.

The test operation conditions were to adjust the wind diameter by attaching the tuyere rings according to the conditions shown in Table 1 below, and to perform the operation by the pulverized coal injection ratio per molten ton (hereinafter referred to as "PCR"). The core temperature was measured using the length measurement using the raceway length measuring device and the core temperature measuring device in the raceway.

In addition, the test operation was confirmed by comparing the furnace bottom temperature, the furnace heat load, and the fuel cost during the test operation period.

PCR (kg / T-P) 120 130 140 150 160 170 180 Fenggu Ring Mounting 0 4 8 12 16 20 24 Opening area (m ² ) 0.523 0.507 0.491 0.474 0.458 0.442 0.425 Wind flow velocity (m / s) 210 218 226 234 242 250 258

The test results are shown in Table 2 below.

Here, the flow velocity of the tuyere was adjusted by symmetrically adding the tuyere rings to each tuyere arranged in a plurality, for example, 24 arranged along the outer periphery of the blast furnace.

PCR (Kg / T-P) 120 130 140 150 160 170 180 Raceway Depth (m) Before Invention 1.7-2.2 After Invention 2.5 2.65 2.54 2.50 2.50 2.57 2.61 Core temperature (℃) Before Invention 1210-1310 After Invention 1350 1355 1344 1352 1348 1345 1389 Lower part temperature (℃) Before Invention 87-150 After Invention 95 105 118 108 117 109 114 Furnace Wall Heat Load (Mcal / H) Before Invention 7450-15000 After Invention 8500 8657 9235 8970 9150 8950 8880 Fuel Cost (Kg / T-P) Before Invention 477-515 After Invention 479 488 491 485 488 484 487

As can be seen from Table 2, as a result of operation by increasing the windball flow rate according to the increase in the pulverized coal blowing ratio, the combustibility is improved by suppressing the formation of bud nest at the tip of the windball when the blowing ratio is increased compared to before the invention. Sediment can be prevented, raceway length can be extended, and stable operation can be maintained without lowering core temperature even when high coal dust is blown.

Based on the embodiment, as shown in the graph of FIG. 4, after determining the air flow velocity by adjusting the air diameter based on the amount of fine coal injection per molten ton, high coal dust operation is carried out to control the furnace bottom temperature and the furnace wall heat load. You will be able to operate.

As described in detail above, the present invention provides an effect that can efficiently perform the high pulverized coal operation by increasing the blowing energy by gradually increasing the wind mouth flow rate when the pulverized coal injection ratio is increased.

Claims (3)

Determining the amount of pulverized coal blown according to the output amount to be produced in the blast furnace; Reducing the diameter of the balloon to increase the flow velocity of the balloon in proportion to the amount of pulverized coal injected by adjusting the balloon diameter of each of the nozzles 31 installed on the outer periphery of the blast furnace after the step; Wind flow velocity management method according to the pulverized coal injection ratio, characterized in that the overall amount of air supplied to the blast furnace in the process of performing the step comprises adjusting to be constant. The method of claim 1, wherein in the step of adjusting the size of the wind blowing, the wind blowing flow rate management method according to the pulverized coal injection ratio, characterized in that the adjustment by the insertion and removal of the wind blowing ring (32) having a variety of diameters. The method of claim 1 or 2, wherein the tuyere ring (32) is installed symmetrically with respect to the center of the blast furnace in the plurality of tuyere (31).