KR100395096B1 - Blast furnace pulverized coal injection method using lignite - Google Patents

Abstract

PURPOSE: A blast furnace pulverized coal injection method is provided which is capable of using lignite that is not usually used as pulverized coal during blast furnace operation through selection of proper coke breeze. CONSTITUTION: The blast furnace pulverized coal injection method using lignite comprises a step of obtaining the minimum average heating value (Qm) according to mixed coal injection quantity in the state that the lignite and coke breeze are mixed with each other in a ratio of 1:1 using heat balance and material balance in blast furnace race way in advance and obtaining a correlational expression between the minimum average heating value and the mixed coal injection quantity of arbitrary lignite and coke breeze through regression analysis by plotting the obtained minimum average heating value; a step of actually measuring heating value (Q2) of lignite to be injected into blast furnace; a step of obtaining the minimum heating value of coke breeze required in the blast furnace using the actually measured heating value of lignite to be injected into the blast furnace and the obtained correlational expression between the minimum average heating value and the mixed coal injection quantity of lignite and coke breeze; a step of analyzing ash content (A) of various types of coke breeze in advance, measuring heating value (Q1) of the various types of coke breeze, and obtaining a correlational expression between the heating value and the ash content of the coke breeze; a step of estimating required ash content of the coke breeze by substituting the obtained minimum heating value of the coke breeze for the correlational expression between the heating value and the ash content of the coke breeze; a step of analyzing the ash content of the coke breeze to be injected into the blast furnace, and comparing the analyzed ash content with the estimated ash content; and a step of selecting a coke breeze in which the analyzed ash content is the same as or less than the estimated ash content so that the selected coke breeze is used as blast furnace injecting coke breeze.

Description

Blast-pulverized coal injection method using lignite

The present invention relates to a method for blowing pulverized coal into the blast furnace blast furnace, and more particularly, to a method for blowing pulverized pulverized coal, which makes it possible to use Dongtan, which is not generally used as pulverized coal during blast furnace operation, by selecting appropriate coke coke. .

Currently, in the blast furnace manufacturing process using blast furnace, pulverized coal injection operation injecting pulverized coal as auxiliary fuel through lance is performed worldwide. The pulverized coal used in the blast furnace pulverized coal injection is limited due to the shape conditions of the blast furnace combustion zone and the characteristics of the process factors, and therefore the properties of coal that can be used in the blowing operation are limited due to high efficiency within a very short combustion time. It is known that coal has a high volatile content in the real industry because the higher the volatile content of coal, the better the combustibility, and practically 30% of the volatile content of coal is used in the pulverized coal blowing operation.

However, in the case of lignite having a very high volatilization content, despite the excellent combustibility in the blast furnace combustion zone, due to the disadvantages in terms of management of calorific value in the combustion zone, the possible blow amount is very low, it is not applied to practical operation. Because the thermal behavior in the blast furnace is quantified in terms of the theoretical combustion temperature in the combustion zone, when the coal dust is blown, the drop in the theoretical combustion temperature according to the blowing is the calorie consumption required for the elevated temperature of the blown coal and the calorific value of the pyrolysis of the pulverized coal. The lowering of the calorific value due to the double pyrolysis is different depending on the inherent compositional differences in the pulverized coal. This is because the consumption of energy is significantly higher than that of the existing coal briquettes, and it causes a significant drop in the theoretical combustion temperature in the blast furnace tip combustion zone. As such, if the theoretical combustion temperature in the tip of the blast furnace drops, the lack of calories at the bottom of the blast furnace lowers the ventilation and liquidity of the bottom of the furnace. This makes the blast furnace operation difficult. Moreover, as the amount of coal dust is increased, the amount of coke charged from the blast furnace is reduced, so that the amount of coal is also required to improve the economic efficiency of the blowing operation due to pulverized coal, and in the case of the use of lignite as described above Due to the limitations of the amount of blown water, the actual blown operation is not performed. Therefore, in order to realize pulverized coal injection operation by using lignite, it is important to develop a technology that can increase the absolute value of pulverized coal injection by preventing the drop in theoretical combustion temperature in the combustion zone when using lignite.

Accordingly, the present invention provides a suitable powdered coke so that the coal is blown through the blowing lance at the same time because the amount of blowing is limited due to the calorie reduction effect of the lower part of the blast furnace blowing operation into the blast furnace blowing zone. The purpose of the present invention is to provide a fine coal blowing method in which lignite can be used by increasing the blowing limit of lignite by maintaining the theoretical combustion temperature.

1 is a graph showing the relationship between the blowing amount of coal pulverized coal species and the theoretical combustion temperature

2 is a graph showing the relationship between the blowing amount of lignite and the theoretical combustion temperature

3 is a graph showing the relationship between the blowing amount and theoretical combustion temperature when lignite and powdered coke are blown in a 1: 1 ratio.

4 is a graph showing the relationship between the blowing amount and the minimum average calorific value when lignite and powdered coke are blown in a 1: 1 ratio.

5 is a graph showing the relationship between the ash content of any powdered coke and the calorific value

In the present invention for achieving the above object in the blast furnace coal injection method,

The minimum average calorific value (Q _m ) according to each mixed blown amount (PCR) is obtained in a state where the lignite and the powdered coke are mixed 1: 1 by using a heat resin and a material resin in the blast furnace combustion zone. (plotting) to obtain a correlation between the minimum average calorific value (Q _m ) and the mixed blowing amount (PCR) of any lignite and powdered coke through regression analysis;

Measuring calorific value Q _{2 of} lignite to be blown into the blast furnace;

Using the correlation between the measured calorific value (Q ₂ ) of lignite to be blown into the blast furnace and the minimum average calorific value (Q _m ) between the lignite and powdered coke obtained above and the mixed blowing amount (PCR), Obtaining a minimum calorific value of the;

Analyzing the ash content (A) of a variety of coke minutes in advance, and also obtaining a correlation between the heat value (Q ₁₎ and the measurement, the heat value of coke minutes (Q ₁₎ and the ash content (A);

Estimating the ash content of the required coke powder by substituting the obtained minimum calorific value of the coke powder into the correlation between the calorific value of the coke generated ash (Q ₁ ) and the ash content (A); Analyzing the ash content of the powdered coke to be injected into the blast furnace and comparing the analyzed ash content with the estimated ash content; And

The present invention relates to a blast furnace pulverized coal blowing method for selecting and using powdered coke for blast furnace blowing, wherein the analyzed ash content is equal to or smaller than the estimated ash content.

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

First, in order to find a relationship between various pulverized coals blown into the blast furnace and the theoretical combustion temperature which can maintain the maximum temperature of the combustion zone according to these pulverized coals, arbitrary coal species having the composition shown in Table 1 below were used.

TABLE 1

In Table 1, coal A is a coal type (coal) that is actually used for blowing in the blast furnace industry, and coal B is lignite which is not blown into the blast furnace due to its high volatilization content, and coal C is simultaneously blown with lignite. Powdered coke for

Figure 1 shows the change in the theoretical combustion temperature in the blast furnace combustion zone according to the injection of A-coal currently used in the actual industry. The theoretical combustion temperature was calculated using the heat balance and mass balance in the combustion zone. In the case of pulverized coal blowing operation, the theoretical combustion temperature decreases as the blowing amount increases, which limits the maximum blowing amount of pulverized coal. In other words, whether or not the theoretical combustion temperature is maintained determines the maximum blowing amount of pulverized coal. As can be seen in Figure 1 when using the A-coal in the blowing range of up to about 200kg per ton of molten iron because it can be maintained at a temperature of more than 2100 ℃ the minimum management level of theoretical combustion temperature in the blast furnace operation is possible stable operation.

2 shows the change in theoretical combustion temperature in the blast furnace combustion zone for the case of blowing only lignite (Sample B) which is not currently used. As can be seen in Figure 2, when blowing the lignite as in the case of Figure 1, the theoretical combustion temperature drops as the amount of fine coal injection increases, as in the above case, but the theoretical combustion temperature according to the increase in blowing amount For the operation of maintaining the theoretical combustion temperature of 2100 ° C in the blast furnace management due to the large drop width, it can be seen that only a low injection of about 100 kg / TP per ton of molten iron is possible, which is very low compared to the case of A injection. This acts as an impediment to preventing the injection of lignite in blast furnace operations. In this way, if a method for solving the problem of the theoretical combustion temperature drop that hinders the blowing of lignite is proposed, the blowing operation using lignite may be substantially performed.

On the contrary, when the lignite and the powdered coke are blown at the same time, the amount of the lignite and the powdered coke that can maintain the theoretical combustion temperature of the combustion zone may be increased.

That is, in Fig. 3, when the lignite (sample B) and the powdered coke (sample C) are mixed and mixed at the same time, the theoretical combustion temperature is changed according to the blowing amount, as shown in Fig. 3. Simultaneous blowing of and coke can reduce the theoretical combustion temperature drop according to the increase of blowing amount, and it can be seen that the theoretical burning temperature can be increased significantly than the case of using only the same blowing amount lignite. Specifically, in case of simultaneous blowing with lignite and powdered coke at 1: 1, the theoretical combustion temperature is maintained up to 180Kg / TP while maintaining the theoretical combustion temperature above 2100 ℃, which is the lowest management level in the blast furnace operation. Could increase.

In this way, the coal and the high calorific value coke are blown at the same time to reduce the degree of theoretical combustion temperature drop, thereby lowering the aeration and liquid permeability of the furnace from the blast furnace combustion zone to the softening fusion zone due to the lack of calories. Preventing the overall instability of the bleeding allows for the actual blowing of lignite.

On the other hand, from the above results, it can be seen that lignite and powdered coke blown to maintain a theoretical combustion temperature of about 2100 ° C. can be up to about 180 Kg per ton of molten iron, while maintaining a theoretical combustion temperature of about 2100 ° C. in various blowing ranges. In case of operation, the minimum average calorific value required for each blowing amount needs to be derived.

For this purpose, when random lignite and powdered coke are blown at a time of 1: 1, the result of plotting the minimum average calorific value required when the blowing amount is increased by using heat and material resin is plotted in FIG. 4. Indicated.

Based on the theoretical data thus obtained, the correlation between the mixed blowing amount of lignite and powdered coke and the minimum average calorific value was calculated through regression analysis as follows.

Qm: Minimum average calorific value of any lignite and powdered coke (Kcal / Kg)

PCR: Mixed blown amount of lignite and powdered coke (Kg / T-P)

In this case, the minimum average calorific value of lignite and powdered coke required to maintain the theoretical combustion temperature control value of 2100 ° C in the blast furnace operation can be easily determined when lignite and powdered coke are mixed in a 1: 1 ratio. have.

In addition, since the minimum average calorific value of lignite and powdered coke is an average of the calorific value of lignite and powdered coke, it may be expressed as follows.

Q ₁ : Calorific value of any coke blown into the blast furnace (Kcal / Kg)

Q ₂ : Calorific value of any lignite injected into blast furnace (Kcal / Kg)

Therefore, if the calorific value Q ₂ is analyzed for any lignite species to be used for simultaneous blowing from the value of the minimum average calorific value obtained in the above formula (1), the arbitrary blowing amount generally set during the blast furnace operation is known. Since is determined, the value of the calorific value of the powdered coke required for blast furnace operation can be easily determined through the above equation (1) (2). In other words,

As a next step, if the size of ash content, which is the most common index of the quality index of powdered coke, can be used as a selection criterion for the selection of powdered coke with the minimum required amount of heat generated, the selection of powdered coke for simultaneous blowing operation It becomes very easy. In the case of powdered coke, the difference of elemental components except ash is insignificant, and it is confirmed that the ash content can be used as a simple selection criterion because it is considered that the excessive amount of ash will act as a factor governing the calorific value. 5 shows the relationship between the ash content of the various types of powdered coke and the calorific value. As shown in FIG. 5, a good correlation was obtained between the ash content of the coke and the calorific value, and the following empirical formula was derived between them by the medium-term analysis.

Q: Arbitrary coke calorific value (Kcal / Kg)

A: arbitrary content of powdered coke ash (%)

As a result, when the calorific value (Q ₂ ) of any lignite species simultaneously blown into the blast furnace is measured and operated with a predetermined pulverized coal injection amount (PCR) of the blast furnace, the value of the maximum allowable ash content of the powdered coke required is given by It can be estimated by.

Therefore, the calorific value (Q ₂ ) of any lignite species simultaneously blown into the blast furnace is measured, and the ash content of the powdered coke blown into the blast furnace is analyzed when operating with a predetermined pulverized coal injection amount (PCR) of the blast furnace. If the value is smaller than or equal to the ash content value estimated in Equation (5), it means that it can be blown into the blast furnace together with lignite to have a sufficient theoretical combustion temperature.

In this way, the present invention is the lignite and the selected lignite once selected to enable the use of lignite which is not practically blown because the amount of blowing is limited due to the calorie reduction effect of the lower part in the pulverized coal blowing operation to the blast furnace blowing mouth The powdered coke suitable for the blowing amount can be selected simply by the ash content, so that the theoretical combustion temperature of the combustion zone can be easily maintained, thereby increasing the blowing limit of lignite and enabling the use of lignite.

As described above, when the blowing operation according to the present invention is carried out, it is possible to reduce the cost of molten iron production by blowing lignite, which has abundant reserves and low cost, into the blast furnace worldwide.

Claims (4)

In the blast furnace coal injection method, The minimum average calorific value (Q _m ) according to each mixed blown amount (PCR) is obtained in a state where the lignite and the powdered coke are mixed 1: 1 by using a heat resin and a material resin in the blast furnace combustion zone. (plotting) to obtain a correlation between the minimum average calorific value (Q _m ) and the mixed blowing amount (PCR) of any lignite and powdered coke through regression analysis; Measuring calorific value Q _{2 of} lignite to be blown into the blast furnace; Bunkers required for the blast furnace by using the correlation between the measured calorific value (Q ₂ ) and the minimum average calorific value (Q _m ) between the lignite and powdered coke obtained above and the mixed blowing amount (PCR) Obtaining a minimum calorific value of the; Analyzing the ash content (A) of a variety of coke minutes in advance, and also obtaining a correlation between the heat value (Q ₁₎ and the measurement, the heat value of coke minutes (Q ₁₎ and the ash content (A); Estimating the ash content of the required coke powder by substituting the obtained minimum calorific value of the coke powder into the correlation between the calorific value of the coke generated ash (Q ₁ ) and the ash content (A); Analyzing the ash content of the powdered coke to be injected into the blast furnace and comparing the analyzed ash content with the estimated ash content; And The blast furnace pulverized coal injection method using lignite, characterized in that for selecting the blast furnace blowing powder coke is less than or equal to the estimated ash content. The method of claim 1, wherein the correlation between the minimum average calorific value (Q _m ) and the mixed blowing amount (PCR) between the lignite and the powdered coke is Blast pulverized coal injection method using lignite, characterized in that represented by. The method according to claim 1, wherein the correlation between the calorific value Q ₁ and the ash content A is Blast pulverized coal injection method using lignite, characterized in that represented by. According to claim 1, Estimation formula for the ash content of the powdered coke required for the blast furnace injection Blast pulverized coal injection method using lignite, characterized in that the display.