JPH05156329A - Method for operating powder injection from tuyere in blast furnace - Google Patents

Abstract

PURPOSE:To stabilize a blast furnace operation and to remarkably reduce costs of raw material and fuel by injecting pulverized coal and powdery iron raw material from tuyeres in the blast furnace and adjusting an opening degree of a hot blast valve and gas quantity for controlling powder injecting quantity in each tuyere. CONSTITUTION:By screening sintered ore from a sintering plant 1 with sieves 3-7, the sintered ore is charged into the blast furnace 19 and the sintered ore powder in minus sieve is injected from the tuyere 17 through a nozzle 18 with carrier gas 15 through a blowing tank 13. On the other hand, a coal 20 is made to the pulverized coal together with slag-making agent 21 with a pulverizer 26 and injected together with carrier gas 32 from the tuyere 34 through a nozzle 35. In the above blast furnace operation, the opening degree of the hot blast valve arranged at a blast branching pipe (not shown in the figure) and/or the gas quantity for controlling powder injecting quantity arranged at a powder feeding pipe (not shown the figure) in each tuyere 17, 34, are adjusted. By this method, the blasting quantity and the pulverized coal injecting quantity, the blasting quantity and the powdery iron raw material injecting quantity in the tuyeres 34 and consumption of coke at the front of the tuyere are controlled so as to always come in the prescribed ranges.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is to blow a large amount of pulverized coal and / or pulverized iron raw material from a tuyere into a blast furnace to alleviate the raw material restriction of the coal / iron raw material and to increase the blast furnace tap ratio. The present invention relates to a blast furnace tuyere powder blowing operation method capable of controlling hot metal components.

[0002]

2. Description of the Related Art Conventionally, as a blast furnace operation mode, a liquid fuel injection operation has been aimed at for achieving a low coke ratio and a high tap ratio by injecting a large amount of liquid fuel such as heavy oil and tar from a tuyere. However, as the price of crude oil soared in the first half of 1975, the energy price system changed drastically, and as a result, all coke operation has become the mainstream of blast furnace operation.

Compared with the liquid fuel injection operation, this all-coke operation has a lower fuel cost, but the theoretical combustion temperature before the tuyere is higher, and the amount of hydrogen input to the blast furnace is also lower, so that the unloading is not impossible. It becomes stable and slips frequently, and the Si concentration in the hot metal rises. This problem has been solved by using a large amount of humidity control, but instead, the problem of coke oven production capacity due to an increase in the coke ratio and the maximum blow-through limit due to an increase in the blast basic unit There is a new problem that the tap ratio decreases.

Therefore, the number of blast furnaces that employ pulverized coal as an inexpensive tuyere-blown fuel has increased, and in such blast furnaces, the reduction of the coke ratio has been achieved and the maximum tap ratio has increased. Today, there are blast furnaces operating in Japan at a pulverized coal ratio of 100 kg / pt or more. For example, "Iron and Steel" vol.73
(1988) s783, Japan Iron and Steel Institute Proceedings, "Materials and Processes" vol.1 (1988) pp.72).

On the other hand, today, as a blast furnace charging material, sinter is used in a large amount of 70 to 95% of the total amount of ore used, and due to its good reducibility and high temperature properties, high iron output of the blast furnace. It contributes to specific operation and low fuel ratio operation.

Here, in the sinter ore manufacturing process, after sintering the sinter, the fine sinter ore under the sieve, that is, the sinter, is returned in the process of crushing and sieving the sinter into a particle size range suitable for use in a blast furnace. Ore is generated and returned to the sintering machine. Usually, the amount of this returned ore accounts for 20 to 30% of the compounding raw material for sintering, and the amount of sinter ore firing is increased by the amount that is not effectively utilized.

[0007] As one of the methods for reducing the amount of sinter ore returned and improving the pot yield of the sinter (product / (new raw material + return ore) * 1000), the re-sieve is installed. , It has been reported that the amount of small-sized sinter in the blast furnace was increased. Proceedings of the Iron and Steel Institute of Japan "Materials and Processes" vol.11
0 (1988) pp. 110).

According to this method, the amount of returned ore was reduced, and the yield of the sinter pot was improved from 75% to 83%. But,
Sintered ore under sieving and re-sieving in the sinter plant is returned to the sinter machine as return ore, so zero return ore is not achieved, and there is an allowance for reduction of firing energy for sinter.

On the other hand, in a blast furnace operating method in which sinter ore is sieved with a particle size of 5 mm and the sinter on the sieve is charged from the top of the blast furnace, the sinter ore under the sieve has a certain particle size, for example, 2 mm. Re-sieving according to the standard and classifying into fine sinter ore and small lump sinter, fine sinter ore is blown into the blast furnace from the blast tuyere, and small sinter ore from the furnace top together with sieve sinter There has also been proposed a method of using a sieving sinter ore in a blast furnace, which is characterized in that it is charged into the furnace. JP 61
See −6204 publication. According to this method, the amount of sinter ore returned ore is reduced to zero, which leads to reduction of the sinter ore firing energy.

Further, as a method for producing low-Si hot metal in a pulverized coal blowing operation, an operating method of blowing fine ore together with pulverized coal has been proposed. See JP-A-57-137402. According to this method, at a pulverized coal ratio of 30 to 150 kg / pt, 5 or more powdered ores consisting of pellet feed or sinter crushed powder are produced.
Degassing reaction (Si ＋ 2FeO ＝ Si by blowing 50kg / pt
Si in the hot metal is reduced by O ₂ + 2FeO).

Furthermore, low Si in pulverized coal blowing operation
-As a method for producing low S hot metal, an operation method has also been proposed in which basic substances such as limestone and dolomite are blown together with pulverized coal. See JP-A-57-137403.

Further, a method has been proposed in which the stock line level for each azimuth in the circumferential direction is adjusted and the deviation for each azimuth of the taphole is alleviated by controlling the amount of pulverized coal blown together with the control of the amount of pulverized coal by the hot air valve. .. See JP-A-1-177307.

[0013]

However, these methods have the following two problems. When injecting a large amount of pulverized coal and / or powdered ore,
In a tuyere with a large amount of powder blown in, the combustion resistance of powder and smelting reduction cause a large air flow resistance and the amount of hot air decreases, so combustion of pulverized coal and / or smelting reduction of powdered ore progresses sufficiently within the raceway. However, it was difficult to continue stable operation because there was a risk that the air flow rate of the branch pipe of the specific tuyere would decrease and the blown powder would flow back and damage the blower branch pipe refractory.

When a large amount of pulverized coal and / or powdered ore is blown in, the temperature distribution in the height direction in the blast furnace rises because the pre-tuyere coke consumption is small and the unloading speed is small at the tuyere with a large amount of powder injection. When the heat pattern in the circumferential direction in the blast furnace becomes unbalanced and the amount of fall of the charge into the raceway increases due to the fall of raw mine, etc., the air flow rate of the branch pipe of the specific tuyere decreases and the blown powder It was difficult to continue stable operation because there was a risk that the air would flow backwards and damage the blast branch pipe refractory.

Thus, the object of the present invention is to monitor and suppress the condition of powder injection for each tuyere in order to solve the above problems in the powder injection operation of a blast furnace in which a large amount of pulverized coal and sintered ore powder are injected. To achieve stable operation of the blast furnace,
Therefore, it is to provide a blast furnace tuyere powder blowing operation method for significantly reducing raw fuel costs.

[0016]

Here, the present inventors
As a result of conducting many experiments in order to achieve the above object, the following findings were obtained.

A blow-branch flow meter and a hot-air control valve are installed in each blow-branch, and the branch-wind volume is adjusted by changing the hot-air valve opening degree in a specific direction in which the branch-branch flow rate instruction value is below a set value. A powder flow meter and a powder flow rate adjusting means are installed in the powder flow pipe to the tuyere to adjust the amount of powder blown in the relevant direction, so that the diametrical deviation of pulverized coal combustion and powder ore smelting reduction And the deviation of the unloading speed in the circumferential direction is alleviated, so that the backward flow of the blown powder to the blast branch pipe can be prevented and stable operation can be continued.

The present invention was made on the basis of such findings, and the gist of the present invention is from the tuyere of a blast furnace.
In the operation of blowing powder that is pulverized coal and / or pulverized iron raw material, the blown air amount and pulverized coal blown amount of each tuyere, the blown air amount and pulverized iron raw material blown amount, and the pre-tuyere coke consumption amount are always within the specified range To adjust the opening of the hot air valve installed in the blower branch pipe of each tuyere and / or the amount of gas for controlling the amount of powder blown in the powder feeding pipe of each tuyere. It is a feature of the blast furnace tuyere powder blowing operation method.

Here, the "powdered iron raw material" includes not only powdered iron ore but also powdered sintered ore. According to a preferred aspect of the present invention, when pulverized coal is blown, slag forming agents such as dolomite and limestone may be blown at the same time.

The above "predetermined range" is not particularly limited thereto, but when the steady value is 100%, it may be within a range of 70%, more preferably 90%.
The range is from ~ 110%. Stable operation is realized by constantly maintaining the operation within this range at each powder blowing tuyere.

The powder injection amount of the pulverized coal and / or the powdery iron raw material from each tuyere can be changed by adjusting the powder injection amount control gas amount. Air is generally used as the control gas, but gases such as nitrogen and oxygen may be used.

[0022]

Therefore, according to the present invention, in the operation of blowing the pulverized coal and / or the powdered iron raw material from the tuyere of the blast furnace,
By monitoring and controlling the powder blowing condition for each tuyere, stable operation was confirmed, and the situation of completely stopping the blown powder was avoided, and the raw fuel cost was significantly reduced under stable operation of the blast furnace. Bring about a reduction.

[0023]

Embodiments of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory diagram of a blowing path performed through pulverized coal, raw iron oxide powder, and tuyere of a slag forming agent in a blast furnace, and FIG. 2 is an enlarged view of a part thereof.

The right side of the center line of the blast furnace 19 shows the blowing process of the sintered ore powder. The sintered ore produced by the sintering machine 2 is a hot screen or cold installed in the sintering plant 1. It is screened by a plurality of screens 3 such as a screen, and the bottom of the screen is supplied to a service hopper 11. On the other hand, the upper sieve is screened by a plurality of sieves 4 to 7 installed in the ironmaking plant, and finally the lower sieve of the sieve 6 is supplied to the service hopper 11, and the upper sieves of the sieves 5 to 7 are , It is charged as a lump material from the top of the blast furnace.

The powder supplied to the powder blowing system is stored in the service hopper 11 and then introduced into the blowing tank 13 via the intermediate tank 12. Blow tank 13
The powder in the inside is fluidized by the gas 14 introduced from the bottom of the tank, is transported by the carrier gas 15, passes through the distributor 16, and is blown into the blast furnace 19 through the blowing nozzle 18 attached to the tuyere 17. Is blown in.

Although not shown in the drawing, the powder blowing nozzles 18 are installed at each air blowing tuyere 17, and a plurality of distributors 16 may be installed, if necessary, in multiple stages, The number of stages of the sieves 4 to 7 in the ironmaking factory may be increased or decreased as necessary.

Next, the left half of the center line of the blast furnace 19 shows the pulverized coal and slag blowing process. The coal 20 loaded in the yard is stored in the coal hopper 22, and then a predetermined amount is continuously supplied to the crusher 26 by the rotary feeder 24 installed in the lower part of the hopper. In the crusher 26, it is crushed and mixed, and dried by hot air having a predetermined temperature within the range of 150 to 500 ° C., which is sent from a hot air oven 27 attached to the crusher 26. As this hot air, one obtained by burning B gas or the like generated in the steel mill may be used.

Coal pulverized to a particle size not larger than a predetermined size is a hot air stove.
Gas is transported to the tuyere 34 toward the tuyere 34 by the hot air from 27, and further distributed to each tuyere 34 via the distributor 33.
Gas is transported. And the blowing nozzle 35 from the tuyere 34
It is blown into the blast furnace 19 through. In this case, if necessary, in the blowing system after the crusher 26, the pipe 32
It is also possible to add hot air and / or cold air via.

If necessary, the slag forming agent 21 such as dolomite and limestone loaded in the yard is stored in the slag forming agent hopper 23, and then a predetermined amount is stored by the rotary feeder 25 installed at the bottom of the hopper. Crusher with coal continuously
It is also possible to supply to 26 simultaneously. The coal and the slag-forming agent, which are simultaneously supplied in a predetermined ratio, are crushed and mixed in the crusher 26 and blown from the tuyere 34 of the blast furnace.

Although not shown, the powder blowing nozzles 35 are installed in each air blowing tuyere 34, and a plurality of distributors 33 may be installed, if necessary, in multiple stages. Although not shown, the system from the yard of the slag-forming agent 21 to the hopper 23 is also installed according to the number of types of the slag-forming agent to be used.

As the slag forming agent, dolomite, limestone and the like are used in the examples, but they may contain other MgO source or CaO source. Further, it may be a slag forming agent containing both an MgO source and a CaO source.

As shown in FIG. 2, a blast branch pipe flow meter 36 and a hot blast valve 37 are installed in each blast branch pipe.
A powder flow meter 38 is installed in the powder injection system for each tuyere, and a powder amount adjusting gas 39 is introduced immediately before the powder injection nozzle 18 of each tuyere to inject the pulverized coal. /
When the amount of air blown, the amount of blown powder ore / the amount of blown air, and the amount of coke consumption in front of the tuyere are out of the predetermined ranges, the opening degree of the hot air valve 37 of the blower branch pipe is adjusted and / or the amount of powder blown in By adjusting the flow rate adjusting valve 40 of the powder amount adjusting gas 39, it is possible to bring them into a predetermined range.

Here, as the powder flow meter 38, either a capacitance type or a differential pressure measuring type (venturi or bend) may be installed. The coke consumption in front of the tuyere is calculated from time to time by a calculator using the blowing conditions (blowing amount, blowing moisture, oxygen, pulverized coal blowing amount / composition, powdered ore blowing amount / composition) and coke composition as input. Is displayed.

The explanation of FIG. 2 is the same for all tuyere, and the same equipment is installed in each blow branch pipe for both the powder ore blowing system and the pulverized coal blowing system.

[0035]

EXAMPLES Below, the experimental results of performing the powder blowing operation of the blast furnace in the A blast furnace (internal volume of 2700 m ³ ) according to the present invention will be explained in comparison with the experimental results based on the conventional method. First, in carrying out the method of the present invention according to FIGS. 1 and 2,
The lower limit set value of the blast branch pipe flow meter 36 was determined from the operation results of the conventional A blast furnace.

FIG. 3 and FIG. 4 show the results, and the fluctuations in the normal operation are constant in all of the blown air amount / pulverized coal blown amount, blown air amount / powdered ore blown amount, and pre-tuyere coke consumption amount. While the value is within 90 to 110% of the value, in the case of Fig. 3, the downfall of the raw mine occurs due to the increase in the amount of pulverized coal injected into the branch pipe. It suddenly dropped to less than%, and an accident occurred in which the blown powder flowed back into the blast branch pipe, resulting in a sudden blast. In addition, in the case of FIG. 4, it is a case where the downfall of the raw ore occurs due to the increase in the amount of the branch powder ore blown in.
The amount of fine ore blown in suddenly dropped to less than 10% of the steady value, and an accident occurred in which blown powder flowed back into the blast branch pipe, leading to sudden breeze. From these results, the lower limit set values for branch air flow / fine coal injection, branch air flow / fine ore injection, and pre-tuyere coke consumption were set to 70% of their steady values.

The experimental results of the blast furnace tuyere powder blowing operation thus carried out are shown in Table 1. Table 2 shows the particle size distribution of the under-sieved sinter and the particle size distribution of pulverized coal used in the experiment. The powder used in this example is sinter -3 mm for ore and -200mesh 90% for pulverized coal, but if necessary, further for ore pellet feed, iron oxide-containing raw material such as blast furnace dust, pulverized coal. As for the above, coarse particles may be blown in.

First, the test period A in Table 1 is an operation example by the conventional method, and the test period B is an application example of the method of the present invention. During the test period A, N
At o.16 and No.22 tuyere, a backflow accident of blown powder to the blast branch pipe due to falling of raw ore occurred, and a sudden break was forced, so stable powder injection operation could not be maintained.
The plan could not be achieved for both powder injection rate and tap ratio.

On the other hand, in the test period B, which is an application example of the present invention, the amount of air blown / the amount of pulverized coal blown and the amount of coke consumed in front of the tuyere at No. 12 and No. 18 tuyeres accompanying the powder blowing. Both were found to be less than the set values, and the pulverized coal blowing amount and hot air valve opening in the relevant direction were adjusted, and the blast amount / pulverized coal blowing amount, blast amount / fine ore blowing amount, and pre-tuyere coke consumption were both set values. Since it was controlled up to, powder injection was continued stably. Further, after a predetermined time, the air flow rate / powdered coal injection rate, air flow rate / powdered ore injection rate and pre-tuyere coke consumption for all blower branch pipes are 90 to 11% of the set value.
It was determined whether or not it was within the range of 0%, and the hot air valve opening and the powder injection amount were finely adjusted. As a result, stable blast furnace operation was continued, both the amount of powder blown and the tap ratio were achieved as planned, resulting in a significant reduction in raw fuel costs.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

As described above, according to the present invention, stable operation can be continued in the blast furnace powder blowing operation in which the pulverized coal and the under-sieved sinter are blown from the blast furnace tuyere by gas transportation. And relaxed coke oven production restrictions,
It is possible to achieve industrially very useful effects such as reduction of sinter ore firing energy and improvement of production elasticity by increasing blast furnace tap ratio.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a device configuration suitable for implementing the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a graph showing changes in relative values of air flow rate / pulverized coal and pre-tuyere coke consumption amount obtained by a preliminary test in an example.

FIG. 4 is a graph showing changes in relative values of air flow / powder ore and pre-tuyere coke consumption obtained by a preliminary test in Examples.

[Explanation of symbols]

1: Sinter plant 2: Sintering machine 3 to 7: Sieve 11: Service hopper 12: Intermediate tank 13:
Blow tank 14: Gas 15: Carrier gas 16:
Distributor 17: Tuyere 18: Nozzle 19: Blast furnace 20: Coal 22: Coal hopper 24: Rotary feeder 26: Grinder 27: Hot air stove 34: Tuyere 35: Nozzle 36: Blower branch flow meter 37:
Hot air valve 38: Powder flow meter 39: Gas for adjusting powder amount 40:
Flow control valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Horisaka 4-53-3 Kitahama, Chuo-ku, Osaka Sumitomo Metal Industries Co., Ltd.

Claims (1)

[Claims] 1. In an operation of blowing powder of pulverized coal and / or pulverized iron raw material from a tuyere of a blast furnace, the blowing amount and the pulverized coal blowing amount of each tuyere, the blowing amount and the pulverized iron raw material blowing amount, and The opening of the hot air valve installed in the blower branch pipe of each tuyere and / or the powder injection installed in the powder feeding pipe of each tuyere so that the consumption of coke before the tuyere always falls within the specified range. A blast furnace tuyere powder blowing operation method characterized by adjusting the amount of gas for controlling the amount.