KR20020027010A - Blast Furnace Operating Method Injecting Fine Coal - Google Patents

Abstract

PURPOSE: A blast furnace operating method for injecting pulverized coal is provided which easily relatively compares combustibilities and controls the injection conditions by deducing the relation capable of evaluating combustibilities for variations of inherent properties of coal and injection conditions of pulverized coal through tests in advance. CONSTITUTION: The blast furnace operating method for injecting pulverized coal comprises the steps of obtaining a standard burning rate predicting formula having volatile matter content of pulverized coal, ash content, particle sizes of pulverized coal, oxygen content during blowing and injection ratio of the pulverized coal as variables; setting standard blast furnace operating conditions; predicting a standard burning rate(η) in the blast furnace operation that is performed under the standard blast furnace operating conditions by the obtained standard burning rate predicting formula; and controlling one or more factors selected from operation factors consisting of volatile matter content of pulverized coal, ash content, particle sizes of pulverized coal, oxygen content during blowing and injection ratio of the pulverized coal so that the burning rate is within the tolerance range of the standard burning rate, or the same as or more than the standard burning rate when a burning rate predicted by the standard burning rate predicting formula is deviated from the tolerance range of the standard burning rate in the operation after prediction of the standard burning rate.

Description

Blast Furnace Operating Method Injecting Fine Coal}

The present invention relates to a blast furnace operating method for blowing pulverized coal through a blowhole in a blast furnace preliminary process (hereinafter, referred to as `` blast furnace ''), and more specifically The present invention relates to a blast furnace operating method for estimating the combustibility of pulverized coal in the blast furnace based on the intrinsic physical properties and the pulverized coal blowing conditions.

Coke is used in blast furnace operation. This coke is the main fuel in the blast furnace operation. The heat generated from combustion and CO gas not only play the role of the main heat source and reducing agent in the blast furnace operation, but are also unique throughout the blast furnace. Since it exists in the solid state, it also has the function of breathability in the upper part of the blast furnace and liquid permeability in the lower part of the blast furnace.

However, as the cocos furnace for manufacturing such coke is deteriorated, the amount of leakage of environmental pollutants is increased, and the burden of cocos furnace is lowered due to the huge investment cost due to the investment in environmental facilities when new facilities are installed. There is a search for a solution.

In view of this, in order to partially replace the role of the conventional coke, the pulverized coal blowing operation through the tuyere has emerged as the main operation technology, and each steel mill is making efforts to develop technologies to increase the pulverized coal blowing cost competitively. .

At present, the results of long-term stable operation with pulverized coal injection cost of about 200kg / t- molten iron, that is, about 40% or more of blast furnace coke usage, are reported.

In the pulverized coal operation, blast furnace operators are most interested in technology development that can inject such a large amount of pulverized coal stably and effectively.

To this end, various operating technologies are being developed in which pulverized coal injected into the blast furnace can be usefully consumed in the furnace.

First of all, the blown pulverized coal is completely burned in the combustion zone, or the unburned char is consumed completely as it rises in the furnace, ultimately representing the percentage of coke saved in terms of the amount of coke saved per unit blown coal dust. I) Operation at high conditions would be most desirable. To this end, a technique for estimating or estimating the combustibility of pulverized coal blown through the tuyere is essential.

As a conventional method for estimating the blast furnace combustion in pulverized coal, a method of estimating the luminance measured by installing a radiation temperature camera in a pit is statistically evaluated. Patent Publication No. 94-9667 (blast furnace pulverized coal combustion control system).

However, according to this method, expensive cameras for obtaining luminance information need to be attached to various air vents, and since reliability of measurement information due to contamination of the air vent observation zones is a problem, there is little track record of being useful in the present furnace. It is true.

On the other hand, a method for estimating the combustibility through the characteristics of the components in the combustion zone and its characteristics [Korean Patent Publication No. 95-18478 (Bulverized Coal Combustion Estimation Method), Korean Patent Publication No. 1997-43077 ( Pulverized coal combustion method) and Korean Patent Publication No. 99-2212 (pulverized coal combustion rate estimation method in blast furnace operation method).

The above methods are used to collect unburned coal, coke, slag, etc. by using a separate sampling device through a tuyere in operation or water purification, and then carefully separate them and perform necessary analysis. Is a method of estimating.

However, the above methods also require a separate sampling device, and there is a problem that the sample taken cannot represent the situation of the combustion zone, and it is possible to improve the combustibility by directly using in the operation using the estimated combustibility. There is a problem that is difficult to suggest.

Therefore. The present inventors have conducted research and experiments to solve the above-mentioned problems of the prior art, and based on the results, the present invention proposes the present invention. The purpose of the present invention is to provide a method for pulverized coal injection furnace operation that can compare the combustibility easily by deriving the relation that can be evaluated through a preliminary experiment and to control the pulverized coal injection operation condition using this.

1 is a partial side view of a blast furnace equipped with a blow pipe and pulverized coal injection lance;

2 is an example of a pulverized coal combustion test apparatus for evaluating the combustion rate according to the present invention

3 is a graph showing the relationship between the combustion rate predicted from the combustion rate prediction formula and the combustion rate measured through the combustion test according to the present invention.

4 is a graph showing the relationship between the combustion rate predicted by the present invention and the content of unburned fuel 노 in top dust;

Explanation of symbols on the main parts of the drawings

One . . . Blow Pipe 2. . . Pulverized coal blow lance, 3. . . Windball

4 . . . Combustion zone 5. . . Upper Furnace 6. . . Induction furnace

10. . . Vacuum container 20. . . blast furnace

The present invention is a blast furnace operation method for blowing pulverized coal,

Obtaining a reference combustion rate prediction formula including volatile matter content of pulverized coal, ash content, pulverized coal particle size, oxygen content during blowing, and pulverized coal injection ratio;

Setting a reference blast furnace operating condition;

Predicting a reference combustion rate (η) in the blast furnace operation performed under the reference blast furnace operating conditions by the reference combustion rate prediction equation obtained above; And

If the combustion rate predicted by the reference combustion rate prediction formula in the operation after the reference combustion rate prediction is outside the allowable range of the standard combustion rate, the volatile content of pulverized coal, ash content, The present invention relates to a pulverized coal injection blast furnace operating method comprising the step of controlling one or two or more selected from an operation factor consisting of pulverized coal particle size, oxygen content during blowing, and pulverized coal blowing ratio.

More preferably, the present invention provides a blast furnace operation method for blowing pulverized coal,

Setting a reference blast furnace operating condition;

Volatile content of pulverized coal (VM,%), ash content (ASH,%), pulverized coal particle size (Dp, μm), oxygen content during blowing (OX,%), and pulverized coal blowing ratio (PCR, kg / t-melt) Obtaining a reference combustion rate (η) prediction equation as a variable as shown in Equation 1 below;

η = 0.594VM-1.01ASH-0.049 Dp + 3.09OX-0.127PCR-14.5

Predicting, by Equation 1, the reference combustion heat? In the blast furnace operation performed under the reference blast furnace operating conditions; And

If the combustion rate predicted by Equation 1 in the operation after the reference combustion rate prediction is outside the allowable range of the standard combustion rate, the volatile ash content of the pulverized coal, ash content, pulverized coal, and the like are within the allowable range of the reference combustion rate or more than the reference combustion rate. The present invention relates to a pulverized coal blowing furnace operating method comprising the step of controlling one or two or more selected from the operating factors including particle size, oxygen content during blowing, and pulverized coal blowing ratio.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

In order to perform the pulverized coal injection blast furnace operation according to the present invention, it is necessary to first obtain a reference combustion rate prediction formula that can predict the reference combustion rate.

The standard combustion rate prediction formula in accordance with the present invention consists of the volatile content of pulverized coal, ash content, pulverized coal particle size, oxygen content in blowing, and pulverized coal blowing ratio.

A preferable example of the reference combustion rate prediction equation will be described.

1 schematically shows a blow pipe 1 and a pulverized coal blowing lance 2 provided in the blast furnace 20.

In FIG. 1, 3 represents a tuyere, and 4 represents a combustion zone.

As shown in FIG. 1, pulverized coal is supplied by a carrier gas through a pulverized coal blowing lance 2 inserted obliquely into a blow pipe 1 installed in a circumferential direction under the blast furnace 20. The silver flows into the combustion zone 4 through the tuyere 3 together with the high-temperature high-velocity gas (typically air) that has passed through the tip of the blow pipe 1. In this process, pulverized coal burns violently with oxygen in the gas.

In the present invention, combustion experiments were carried out under various blowing conditions on various types of coal using an experimental apparatus that can simulate the situation of the combustion zone.

2 schematically shows an example of a combustion zone simulated pulverized coal combustion testing apparatus.

This experimental device is designed to evaluate the combustibility during the passage of high temperature region in a very short moment by using the pressure difference and is designed to simulate the zone of combustion zone.

Referring to the method for evaluating combustibility using the experimental apparatus as follows.

The combustion gas was heated up to 1200 ° C. through the upper electric furnace 5, and a high temperature range of 1700 ° C. was maintained using the induction furnace 6. Through the sample input unit 7, the appropriate amount of sample coal was introduced based on the operating conditions of the blast furnace operation to simulate the ratio of pulverized coal injection ratio.

Once the preheating of the reaction gas supplied from the reaction gas storage tank 8 and the temperature rise of the combustion zone are completed, a certain amount of sample is charged and the vacuum pump 9 is operated to maintain the vacuum container 10 in vacuum. At this time, the pressure of the preheating gas is maintained at about 1.5 atm and the sample coal feeding pressure at 4.0 atm. When all of these conditions were completed, the solenoid valves 11 and 12 were simultaneously opened to allow the preheated air and the sample coal to rapidly pass through the high temperature section due to the pressure difference.

The electronic valves 13 and 14 were then designed to open quickly. The coal 석탄 after the reaction was to be contained in the sampling port (15) consisting of a plurality of stainless steel mesh, the burnability was calculated by the following equation based on the ash content (%) of the coal 회수 recovered after each experiment.

_{η = (1-ASH 1 /} ASH 2) / (1-ASH 1/100) × 100

Where η represents the combustion rate (%), ASH ₁ represents the ash content (%, db) of the sample coal, and ASH ₂ represents the ash content (%, db) of 후 after combustion.

At least three experiments were carried out for each condition, and if there were many deviations, the arithmetic mean value of the other three experiments was calculated except for two of the two results among the two experiments. It was set as the combustion rate.

There were 12 types of coal used in the experiment, and various coal types were selected, with volatile matter content of 7.2 ~ 32.6% and ash content of 6.5 ~ 17.1%. 3800m ³ of internal volume of pulverized coal injection operation are based on the change ratio of the actual blast furnace pulverized coal injection ratio was 120, 180, 240 kg / t- molten iron and oxygen content in the air flow was varied to 21, 22, 24 and 26%. The particle size of the pulverized coal was in the range of 21 to 315 µm.

Based on the experimental results, the intrinsic volatile matter content (VM,%), ash content (ASH,%), particle size (Dp, μm), and the oxygen content during blowing (OX,%) and pulverized coal blowing were used. As a result of the correlation analysis with the pulverized coal combustion rate (η,%) using the ratio (PCR, kg / t-molten iron) as an independent variable, a correlation equation (reference combustion rate prediction formula) as shown in Equation 1 was obtained.

(Equation 1)

η = 0.594VM-1.01ASH-0.049 Dp + 3.09OX-0.127PCR-14.5

3 shows the relationship between the combustion rate obtained using the reference combustion rate prediction equation and the actual combustion rate measured through the combustion experiment. As can be seen from this, the correlation is very excellent.

The reference combustion rate prediction equation is derived from an experiment that simulates combustion zone conditions and is not exactly the same as that of combustion conditions in an actual blast furnace.

However, the combustion rate may be relatively compared using only the information on the intrinsic physical properties of the coal blown and the operating conditions.

In addition, the results may be used to provide an operator with control information on adjustable operating factors to ensure appropriate combustibility or to improve combustibility.

In view of the above-described advantages, the present invention provides a reference combustion rate prediction formula obtained in the operation after the reference combustion rate prediction, preferably, when the combustion rate predicted by Equation 1 is outside the allowable range of the reference combustion rate, The pulverized coal injection blast furnace operation is controlled by controlling one or two or more selected from the operating factors including volatile matter content, ash content, pulverized coal particle size, oxygen content during blowing, and pulverized coal blowing ratio so as to be within an allowable range or higher than the standard combustion rate. .

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

(Example)

This experiment was conducted on a blast furnace with an internal volume of 3800m ^{3 during the} operation of pulverized coal injection.

When a new type of coal is blown in place of pulverized coal, which has been conventionally injected in a stable manner, it is possible to predict the combustibility of the conventional blast furnace operation from the correlation equation (Equation 1) derived from the present invention, and then approach the combustion value. The results of changing the controllable operating factors are summarized and the results are shown in Table 1 below.

Operating conditions Coal type VM (%) ASH (%) Dp (μm) OX (%) PCR (kg / t) η (%) 촤 (%) Existing operation A 30.1 8.8 103 24 154 44.2 4.3 Comparative Example 1 B 27.2 8.4 130 23.5 169 37.8 11.2 Inventive Example 1 B 27.2 8.4 89 24 171 41.2 8.3 Comparative Example 2 C 32.7 7.4 141 23 168 41.8 6.2 Inventive Example 2 C 32.7 7.4 141 24 162 44.0 0 Inventive Example 3 D 26.3 8.3 93 23.5 150 43.7 5.3

In Table 1, VM is the volatile content, ASH is the ash content, Dp is the particle size of pulverized coal, OX is the oxygen content during blowing, PCR is the pulverized coal injection ratio, η represents the combustion rate calculated from the above correlation. The numerical value expressed by 촤 represents the area ratio of unburned fuel 된 caused by pulverized coal by visual observation by separating the carbon component contained in the upper blast furnace gas and visual observation with an optical microscope. At this time, the carbon discharged through the top is composed of angled coke and spherical or rounded shape 촤 and measured after surface polishing by fixing at least 10g of sample. The reason why the ratio of char in the top discharge dust is measured is to compare with the combustion rate predicted value in the present invention in view of the fact that the amount of unburned char that is not consumed in the furnace and discharged to the top under the combustible conditions is large.

In Table 1, the existing operating condition was a period of maintaining a good blowing condition, and based on this pulverized coal blowing condition, the operating factors that could change the combustion rate estimation value at different blowing conditions were changed.

That is, as shown in Table 1, the condition of Comparative Example 1 is a blowing condition having a low volatile matter content and a high pulverized coal blowing ratio, and the combustion rate predicted value according to the present invention and the amount of unburned char discharged through the top were measured.

On the other hand, the condition of the invention example 1 was to reduce the particle size and increase the oxygen content in order to increase the combustion rate according to the present invention, the combustion rate predicted value was increased, and thus the amount of the top discharge 촤 could be greatly reduced.

Meanwhile, the conditions of Comparative Example 2 and Inventive Example 2 show the case of blowing coal C, and the case of Inventive Example 2 operated by setting the fine coal injection conditions by predicting the preliminary combustion rate rather than Comparative Example 2 is shown in Table 1 above. As a result, a good combustibility was obtained. The condition of Inventive Example 3 shows a case in which coal D having a low volatile content is blown, and even in this case, it can be seen that a smooth pulverized coal blowing operation can be carried out by predicting a preliminary combustion rate and presetting an appropriate oxygen enrichment rate and crushing particle size. have.

FIG. 4 summarizes the combustion rate calculated by the present invention shown in Table 1 and the content of char in dust contained in the top gas, and is shown in FIG. 4, as can be seen from the above. It can be seen that the amount of unburned 배출 emitted tends to decrease.

As described above, according to the present invention, the combustion rate can be easily estimated by the volatilization content, the ash content and the pulverized coal particle size, the oxygen content during blowing, and the pulverized coal blowing ratio, which are the intrinsic properties of coal. There is an effect to control the pulverized coal blowing operation for.

Claims (2)

In the blast furnace operation method of blowing pulverized coal, Obtaining a reference combustion rate prediction formula including volatile matter content of pulverized coal, ash content, pulverized coal particle size, oxygen content during blowing, and pulverized coal injection ratio; Setting a reference blast furnace operating condition; Predicting a reference combustion rate (η) in the blast furnace operation performed under the reference blast furnace operating conditions by the reference combustion rate prediction equation obtained above; And If the combustion rate predicted by the reference combustion rate prediction formula in the operation after the reference combustion rate prediction is outside the allowable range of the standard combustion rate, the volatile content of pulverized coal, ash content, The method for operating pulverized coal blast furnace comprising the step of controlling one or two or more selected from operating factors including pulverized coal particle size, oxygen content during blowing, and pulverized coal blowing ratio. The method of claim 1, wherein the reference combustion rate prediction formula is (Equation 1) η = 0.594VM-1.01ASH-0.049 Dp + 3.09OX-0.127PCR-14.5 Pulverized coal blowing blast furnace operation method characterized in that