KR20010054887A - A method for balancing amount of the coal feeded into the blast furnace - Google Patents

Abstract

PURPOSE: Provided is a circumference balancing method for the amount of fine coal injected to a blast furnace, which distributes the fine coal equally according to directions of the circumference and controls effectively the temperature of a part having a low molten iron temperature. CONSTITUTION: The circumference balancing method comprises the steps of: installing fine coal flow controlling valves(46)(46') to fine coal injecting lines(48)(48') mounted along the outer circumference of the blast furnace; dividing the fine coal injecting lines into at least two zones; if one zone increase in temperature, controlling differently the fine coal flow controlling valve of the zone and opening size of the other zone.

Description

A method for balancing amount of the coal feeded into the blast furnace}

The present invention relates to a circumferential balancing method for blast furnace pulverized coal injection, in particular, by installing a flow-type flow control valve capable of adjusting the opening degree immediately after the distribution valve of the pulverized coal injection pipe and setting four zones for each outlet. It is related with the blast furnace coal injection quantity circumferential balancing method which adjusts the valve of the three zones of the high side to the prescribed valve opening, and supplies pulverized coal additionally to the side with a low temperature.

In general, the blast furnace operation is an operation to produce molten iron and slag by charging iron ore and coke in the upper part of the blast furnace, blowing hot hot air through the hot blast holes in the blast furnace, and reducing molten iron ore by reducing gas. At this time, the charged iron ore is mainly used sintered ore, pellets, grain ore, coke, pulverized coal and the like as a fuel.

Iron ore at room temperature is charged to the blast furnace, and it takes about 5.5 to 6.0 hours to get to the molten iron through chemical reaction with coke and pulverized coal.

While the iron ore descends, the hardened iron ore at the upper part of the blast furnace contacts the reducing gas to initiate a reduction reaction, and the contents of the blast furnace start to soften and melt. In the lower part of the blast furnace, the charge is completely melted and lowered in the form of molten iron, and then discharged through the tap.

On the other hand, when the contents are unevenly distributed in the blast furnace, or when the mixing ratio of iron ore and coke is unbalanced locally, a reduction in the circumferential direction occurs. And, due to this cause, the molten iron temperature varies due to the difference in reducing ability in each circumferential direction at the moment when iron ore melts through the reduction process and comes out as molten iron. Therefore, the reduction reaction of iron ore does not proceed sufficiently at the low temperature region.

On the other hand, such a variation in the molten iron temperature causes a deviation in the tap opening temperature. Although there is no difficulty in drawing work at the molten iron temperature of about 1510 ~ 1520 ℃, the unbalance occurs in the circumferential direction. Becomes difficult. The reason is that when molten iron temperature decreases, slag fluidity decreases, so it is difficult to separate the wire rod (melting iron and slag), and the low level rise due to poor slag discharge and the discharge due to delayed expansion of the exit port. Defects and exit troubles due to excessive increase in silicon [Si] during molten iron make the blast furnace operation difficult.

Figure 1 shows the basic concept and the temperature deviation phenomenon according to the circumferential direction in the blast furnace operation in general.

In the blast furnace operation, the basic concept of molten iron temperature control is generally to increase the coke charge amount (1) through the upper part of the furnace or to increase the amount of fine coal injection (2) through the air vent at the bottom of the furnace, or to temporarily reduce the air volume (3), The operating means, such as the temporary reduction of the blowing amount 4, is utilized.

Above all, as an effective means when the temperature in a specific direction decreases, a means of increasing the coke charge amount or increasing the amount of pulverized coal injection in the lower part is utilized.

However, as indicated by the arrow 5, when the coke is charged into the upper part of the furnace, it acts as heat after about 5 to 6 hours, and in this case, it is delayed in time and overlaps the thermal action, which is economically desirable. I can't. In addition, the current charging method does not have a system capable of intensively charging coke in a specific direction of low temperature.

In general, the thermal deviation phenomenon, as a rule of thumb, decreases the temperature at a particular outlet side, which is one of the four outlets, and adversely affects the starting operation when the temperature decreases.

2 is a method of increasing the molten iron temperature when the fine coal injection amount of the conventional blowhole is temporarily increased. That is, according to this method, although responsiveness may be faster in 2 to 3 hours (22) in time than in case of charging (21) (5 to 6 hours) in the bottom of the coke, only in the direction of low temperature (25) There is a drawback that it is not possible to intensively input calories.

In the current ARMCO pulverized coal system, there is no flow control function for each branch, so the blowing amount needs to be increased (27) for the blowhole, and the low temperature part (25) can raise the temperature in this way. Although the high temperature part (23, 24, 26) has the same amount of calorific input, the molten iron temperature is higher. In this case, one of the conventional methods is to close the pulverized coal intake pipe valve at the high temperature side and to ground the coal at the lower temperature. It is about increasing the molten iron temperature by making more distribution.

That is, as shown in FIG. 3, when the temperature of the # 3 exit port 33 is low, the 3-4 blowing pipes 35 of the exit # 2 exit port 32 having the highest temperature are locked and the remaining 1 This is to increase the pulverized coal to the 3,4 starting port.

This method also has a temporary temperature increase effect, but there is a limit that it is not possible to intensively inject calories into a specific portion 33 having a low temperature, and when the injection of pulverized coal is temporarily stopped at a high temperature portion 32, The temperature may drop, resulting in further breakdown of the circumference.

Normally, the temperature deviation for each exit port does not occur over several days, but over at least one month to as many as three months. Thus, the above method may be possible as one operation action factor, but may not be the ultimate solution.

As described above, when molten iron temperature deviation by circumference occurs due to pulverized coal circumferential balance deviation, conventionally, the amount of coke is charged from the top of the blast furnace or the amount of pulverized coal blown through the blast furnace is increased by temporarily increasing the heat input from the outside. A method of increasing instantaneously or cutting 3 to 4 pieces of pulverized coal on the side of high molten iron temperature was used.

However, these methods have a temporary effect to solve the temperature deviation, but there is a drawback of not being able to intensively input heat only in a specific direction where the temperature decreases. There is a problem such as quality instability due to the rise of the silicon.

Therefore, there are three methods that have been used conventionally to solve the temperature drop in a particular direction. One of them is to add more coke as a heat source at the top of the furnace when the temperature decreases in a specific direction, and it can act to raise the molten iron temperature by increasing the reduction reaction when it descends to the bottom of the furnace, but it takes more than 5. 5 hours. Another method is to increase the input calorie through the air vents in the lower part of the furnace to temporarily increase the pulverized coal injection ratio, but this method also increases the heat input even in the high temperature direction as well as the specific direction where the temperature is high. have.

Another method is the selective pulverized coal blowing operation method, which closes the valve between the pulverized coal blowing (3-4 flutes of 34 flutes) in the direction of high temperature, and supplies the pulverized coal to the remaining flares by the amount. This method is also effective temporarily, but circumferential unbalance occurs when the temperature is lowered in the direction where the pulverized coal is not blown when used for two days or more.

Therefore, all three methods have problems in terms of economics and blast furnace management, and have the following specific problems when using the conventional methods.

First, in general, when the coke charge amount is increased in order to increase the input calorie in the upper part of the furnace, it takes about 5 to 6 hours or more for the coke to descend to the lower part and act thermally.

Therefore, the charge should be made 5 to 6 hours before the opening of the corresponding opening, and even if the opening is changed, the opening order may not be effective.

In fact, if the furnace adjustment action is taken in the blast furnace operation, it is most effective 2 to 3 hours ago.

If the heat is excessively reduced, the action for raising the heat is too slow 5 hours ago, and before the heat rise is already taken through other means, the result is a duplicate heat action, which is disadvantageous in terms of economic feasibility. Reduced operating efficiency

Second, there is a method of increasing the amount of heat input at the low temperature part by temporarily increasing the amount of pulverized coal blown 2 to 3 hours before the time of the start of the corresponding low temperature exit port. This method also has a temperature raising effect, but the problem of increasing the fuel input as a whole by increasing the heat input not only in a specific direction of low temperature but also in a direction of high temperature, and there is a problem of raising the blast furnace fuel cost in addition to the high temperature direction.

In case of additional heat input in the direction of high temperature, molten iron (Si) increases due to excessive rise in molten iron temperature (1540 ℃), and the slag basicity increases and slag fluidity decreases, making it difficult to work out.

In addition, if the silicon rises during the molten iron, the expansion of the tapping port is delayed, so it is difficult to improve the speed of tapping. If the molten silicon is different from each tap, the preliminary processing time increases and efficiency in the steelmaking pretreatment process. Problems such as deterioration occur.

Third, the pulverized coal blast furnace system of the Gwangyang blast furnace is a system that cannot control the flow rate by blowing branch as amco type, and it is impossible to control the flow rate by the circumferential direction.

The method of adjusting the pulverized coal injection is effective in the short term when the method of closing the valve of the pulverized coal injection in the direction of high temperature (usually 3 to 4 blowholes of the blowholes) and increasing the amount of pulverized coal to the remaining blowholes by that amount. However, there is a disadvantage that can not be used in the long term.

In the case of closing the pulverized coal branch at the higher temperature, the pulverized coal will be distributed to the lower branch. However, this method does not concentrate heat in a specific direction where the temperature is lower, but is distributed to the remaining 30 air vents. The lower temperature can be shifted to a lower temperature, which may cause additional temperature unbalance in the circumferential direction.

Thus, this may be a temporary solution but not a long-term solution.

The present invention is to solve the above problems, when the molten iron temperature deviation in the circumferential direction is effectively controlled by the pulverized coal injection amount by direction to evenly distribute the pulverized coal without unbalance in the circumferential direction, through the gas flow distribution adjustment It is an object of the present invention to provide an operation method for effectively controlling the temperature of a portion having a low molten iron temperature.

The above-mentioned object is to provide a pulverized coal injection amount circumferential balancing method in the circumferential balancing method. A blast furnace comprising a second step of dividing into at least two zones and a third step of differently adjusting the opening ratios of the pulverized coal flow control valve and the other zones when the temperature of one of the respected zones increases. The pulverized coal injection amount is the main balancing method.

1 is a view showing a calorie input and heat adjustment method in the blast furnace operation.

Figure 2 is a view showing a conventional circumferential balance cancellation method.

Figure 3 is a view showing a conventional circumferential balancing method.

Figure 4 is a view showing the pulverized coal flow control valve position and valve configuration of the present invention.

5 is a schematic diagram of a method for pulverizing pulverized coal circumference balance of the present invention.

6 is a view showing a heat adjustment system of the present invention.

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

41, 41 ': Pulverized coal transfer line

42, 42 ': Pulverized coal distribution valve

43, 43 ': Punggu

44, 44 ': manual valve

46, 46 ': Pulverized coal flow control valve

45, 45 ': trilateral

47, 47 ': Blowing pipe air purge line

48, 48 ': Branch pipe line

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

Figure 4 is a pulverized coal flow control valve position and valve configuration diagram of the present invention, Figure 5 is a view showing a pulverized coal circumferential balance deviation solution of the present invention, Figure 6 is a view showing a furnace adjustment system of the present invention.

It shows the position and configuration of the flow control valve among the pulverized coal blowing equipment, and the pulverized coal blowing equipment manufactures pulverized coal from the manufacturing equipment and collects them into distribution valves 42 and 42 'located at the top of the blast furnace through the transfer lines 41 and 42'. . The distribution valve is divided into 34 blowing pipes into 2 series, with odd number 17 A-style (# 1 to # 33), and even number 17 B-number (# 2 to # 34).

When pulverized coal is blown into the blast furnace from the distribution valve, it passes through two valves, namely, manual valves 44 and 44 'and three-way valves 45 and 45', respectively. The three-way valve is a valve for passing through the blocked portion by purging the air (47, 47 ') when the injection pipes 48, 48' are blocked, and is normally positioned to allow the pulverized coal to pass through. On the other hand, reference numerals 43 and 43 'are air holes.

Therefore, the present invention is to attach the pulverized coal flow control valves 46 and 46 'which are located at the rear end of the three-way side and whose opening degree is adjustable. The reason why this valve should be located immediately after the distribution valve is that pulverized coal is supplied from the PCI installation to the distribution valve through the 125mm pulverized coal transfer line (41, 41 ') and 40mm underground line (48,48') is again supplied from the distribution valve. It is divided into each wind hole (43, 43 '). Because of the characteristics of the ARMCO system, adjusting immediately after the distribution valve is good in terms of flow control and is optimal in terms of safety.

The valves of the existing PCI line are ball valve type, and the high pressure (5.5Kg / ㎠) fluid and pulverized coal (specific gravity about 1.0) pass at high speed. It is easy to wear due to its characteristics, and experienced many breakages of the branch pipe line.

Therefore, the valve is not a conventional ball valve or gate-type valve, but a valve-type valve that can maintain a circular shape even when the valve is closed.

The material of the valve is not a cast steel product but is made of a valve disc made of materials of abrasion-resistant and high-strength Hi-Cr system, or made of a special rubber (RUBBER) product to withstand abrasion. Pulverized coal feed pipe) is also made of wear-resistant steel pipe.

5 is a perspective view of a method for eliminating pulverized coal column drift deviation using the present invention.

Basically, the pulverized coal intake pipe is composed of 34 pieces, and the flow deviation 51 is generated for each branch pipe as shown in the figure.

Error limit is ± 5. 0% but in severe cases ± 10. Sometimes it exceeds 0%.

The cause of the flow difference is caused by the difference in distance from the distribution side to the wind hole, which is the difference factor in the input of pulverized coal in the specific direction of each pipe (52, 53), and in severe cases, it causes the breakage of the cylinder balance and the molten iron temperature. . Therefore, when the clearance-type high wear-resistant valve developed in the present invention is attached as shown in FIG. 4, it is possible to effectively improve the flow rate variation for each branch pipe.

The flow deviation measurement for each branch can be confirmed through manual measurement and flow meter (measured at the position of 48,48 ') as shown in FIG. 4, and the flow rate of each branch can be optimized by adjusting the flow control valve. ) can do.

FIG. 6 is a schematic diagram of a thermal drift reduction system using the present invention, and the pulverized coal ARMCO system employed in Gwangyang is a system designed to not allow individual control of flow rate for each branch pipe in order to increase the heat input amount by controlling the flow rate in a specific direction. It should be provided with a system for controlling the pulverized coal flow as shown in FIG.

In this method, four zones are set for each exit direction, and each zone (61, 62, 63, 64) is composed of seven branch pipes, and the first zone (31) is a branch pipe (28, 29, 30, 31, 32). , 33, 34), and the second zone consists of the intake pipes (1, 2, 3, 4, 5, 6, 7), and the third zone contains the blown pipes (11, 12, 13, 14, 15). , 16, 17), and the fourth zone consists of blown pipes (18, 19, 20, 21, 22, 23, 24).

Assuming 200Kg / T-P blown, one branch is 5. 8Kg / T-P, and the amount of blown in one zone is about 40.6Kg / T-P. Therefore, the total amount of blown in three zones is 121.8Kg / TP, and when the temperature of one zone decreases, the three-zone blow valve is closed by a certain degree, and the amount of heat in one zone is increased by that amount. You can increase the input.

According to the temperature drop width, the valve opening can be attached as a type that can be adjusted. If the temperature of the outlet # 3, which is a specific outlet, decreases, the opening degree of zones # 1, 2, and 4 can be adjusted at a constant ratio.

When the temperature of # 3 exit port 63 decreases by 10 ~ 15 ℃, the openings (61,62,64) of # 1,2,4 zones are closed by 5%, and when the temperature decreases by 25 ~ 30 ℃, # 1,2,4 zones Closes the valve opening of 10% and decreases the temperature of 45 ~ 50 ℃ by 15% and closes the opening of the # 1,2,4 zone by 15%. 20% closing and blowing the pulverized coal can solve the temperature deviation.

For reference, the blowing ratio of 1Kg / T-P has a calorific value that increases the molten iron temperature by about 3 ° C. The adjustment of the valve opening in each of the four zones is motorized and systemized so that it can be adjusted in the cab, and functions to be adjusted in one zone unit and individual branch pipes.

Branch numbers # 8, 9, 10, 25, 26, and 27, however, are excluded from the adjustment system because they have a minimal effect on the heat since they are separated from the starting position.

In this method, it is possible to raise the total blowing amount effectively to raise the temperature of any specific outlet area without excessive increase in fuel cost, and make the best use of the existing ARMCO system.

Another difference from the conventional method is that it can raise the temperature of the low temperature exit port without maintaining the pulverized coal injection in the specific high temperature direction and maintain the circumferential balance evenly.

For reference, in the case of a ride in a foreign country that is different from Gwangyang, the pulverized coal injection pipe and the air pipe for transport are separately installed for each blown pipe to adjust the blown flow rate of each pipe. (Control) A system is required.

The operation of the present invention will be described in detail with reference to the accompanying drawings.

First, the playable high wear resistance valve according to the present invention is attached to 34 developments of pulverized coal injection pipes, the flow rate is measured for each branch pipe by using a flow meter, and the passage flow rate is equally adjusted through the valve opening adjustment.

This maintains the amount of pulverized coal injection in the circumferential direction evenly, and provides a function to prevent instability such as fluctuations in gas in the furnace.

Then, during normal blast furnace operation, when the temperature drops excessively at a certain outlet (-15 to -50 ° C), the temperature deviation is increased by adjusting the opening degree for each blowing pipe direction installed in the pulverized coal distribution valve. I can solve it.

As a specific method for solving the temperature deviation, four zones are set for each exit direction, and seven blown pipes are set in each zone.

Zone # 1 is the blowing branch # 28,29,30,31,32,33,34, # 2 consists of # 1,2,3,4,5,6,7 and # 3 is 11,12,13, 14,15,16,17 # 4 consists of 18,19,20,21,22,23,24.

Assuming 200Kg / T-P blown, one branch is 5. 8Kg / T-P, and the amount of blown in one zone is about 34.8Kg / T-P. Therefore, the total amount of blown in three zones is 100. 4Kg / TP, and when the temperature of one zone decreases, the three-zone blow valves are closed by a certain degree, and the amount of heat input to a specific part is increased by that amount. Let's go.

Depending on the temperature drop, the valve opening should be adjusted by type. If the temperature of the exit # 3, which is a specific outlet, decreases, open the # 1, 2, or 4 zones at a constant ratio.

On the other hand, when the input calorific value is increased in the furnace for temperature balance, it takes about 5 to 6 hours or more until COKE is charged to affect the heat. Therefore, the charge should be made 5 to 6 hours before the opening of the corresponding opening, and even if the opening is changed, the opening order may not be effective.

Therefore, in the present invention, a tool for controlling the amount of pulverized coal injection, which is the most responsive among the rising operation operations, is applied, so that the result can be known in 2 to 3 hours when the thermal adjustment action is taken compared to the conventional method. .

In addition, unlike the existing method, there is no need for overlapping thermal action, it is advantageous in terms of economic efficiency, and it can solve problems such as rising fuel costs.

In addition, the present invention is a method for increasing the heat input to a specific part of the low temperature, by increasing the heat input in the direction of high temperature as well as the specific direction of the low temperature, which is the existing method to increase the heat input as a whole to increase the furnace heat excessively This can solve the problem. In case of additional heat input in the direction of high temperature, molten iron (Si) increases due to excessive rise in molten iron temperature (153 ° C), gradation of alkalinity, increase in slag fluidity, etc. In this case, it is possible to minimize the variation of molten iron silicon by intensively injecting heat in the low temperature area and to prevent the variation in molten iron temperature.

When closing the valve of the pulverized coal injection pipe in the high temperature direction and increasing the pulverized coal to the remaining air vents by the amount, it is possible to resolve the temperature deviation, but this is not limited to intensively injecting heat in a specific direction where the temperature is low. have.

In addition, when the three to four valves of the blowing pipes in the high temperature direction are locked, the heat input decreases in that direction, which may further cause unbalance in the circumferential direction.

Therefore, in the present invention, thermal compensation can be effectively performed without breaking the circumference balance by a method of slightly reducing the amount of blowing at the higher temperature and increasing the amount of calorie injection at the lower temperature.

When the temperature unbalance for each circumferential direction occurs according to the present invention, there is an effect of quickly correcting this to maintain a constant temperature balance for each circumferential direction.

The foregoing is merely illustrative of the preferred embodiments of the present invention and those skilled in the art to which the present invention pertains may make modifications and changes to the present invention without departing from the spirit and gist of the invention as set forth in the appended claims. have.

Claims (2)

In the blast furnace pulverized coal injection amount column balancing method, An installation step of respectively installing a pulverized coal flow control valve in each pulverized coal intake pipe which is provided in the circumferential direction outside the blast furnace, A division step of dividing the plurality of pulverized coal injection pipes into at least two zones; The pulverized pulverized coal injection amount circumferential balancing method of the blast furnace pulverized coal injection characterized in that the three steps of adjusting the opening degree of the pulverized coal flow control valve and the other zone in the corresponding zone when the temperature of one of the respective zones increases. The method of claim 1, wherein each of the zones is divided around the exit of the blast furnace blast furnace pulverized coal injection amount circumferential balancing method.