JP2003160805A - Method for blowing oxygen-containing powder from blast furnace tuyere - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for blowing oxygen-containing powder into a shaft furnace type high-temperature reactor such as a blast furnace. <P>SOLUTION: The method for blowing the oxygen-containing powder from the blast furnace tuyere comprises separately supplying the oxygen-containing powder from the inside of a central pipe, nitrogen from between the central pipe and an middle pipe, and oxygen from between an outer pipe and the middle pipe, when using a triple pipe lance in order to blow the oxygen-containing powder; or separately supplying the oxygen-containing powder from the inside of the inner pipe, and nitrogen from between the inner pipe and the outer pipe, when using a double pipe lance; and adjusting and controlling velocity or quantity of a nitrogen flow from the outer pipe, to allow a combustion focal position to freely change; and further using inert gas or air as an alternative to nitrogen. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an oxygen-containing powder blowing method for blowing oxygen-containing powder into a shaft furnace type high temperature reactor such as a blast furnace.

[0002]

2. Description of the Related Art A blast furnace for iron making can produce a large amount of pig iron and has a high thermal efficiency of 90%. Therefore, it is still the mainstream of pig iron production. However, since the blast furnace is a huge countercurrent moving bed, there are problems in productivity, production elasticity, etc.
Further improvement of controllability is desired in order to secure stable productivity and hot metal quality.

Further, in the blast furnace, from the viewpoint of strengthening the cost competitiveness of the iron source, a large amount of cheap raw fuel is used and a high pulverized coal specific high O / C operation is being implemented. For example, the pulverized coal ratio is 100 kg
/ T or more pulverized coal is blown from the blast furnace tuyere, and operation of high pulverized coal ratio high O / C such that the charge weight ratio (O / C) of ore and coke per charge is 4.0 or more Below, increase in the powder ratio in the furnace with an increase in the pulverized coal ratio and sagging of the cohesive zone with an increase in O / C occur, and in particular, the ventilation and liquid permeability of the blast furnace core are likely to decrease. . Decrease in ventilation and liquid permeability of the core of the blast furnace causes a problem of non-uniformity of hearth molten metal flow. Therefore, in order to continue stable and highly productive operation, a high pulverized coal ratio of high O / C is required. The establishment of an effective core activation technology during operation is desired.

As a countermeasure against the decrease in the air permeability and liquid permeability of the blast furnace core, there are several methods for activating the core in addition to the conventionally known increase in fuel ratio and addition of steam. Is disclosed. For example, JP-A-6-93319.
In Japanese Patent Laid-Open No. 6-93320, the characteristics of the blast furnace core are measured by measuring the characteristics of the core of the blast furnace through a plurality of tuyere when the blast furnace is in a blast, and the state of the core is determined and the core that needs to be heated. There is a method in which a hollow pipe is inserted from a tuyere in the vicinity of a part and a coke in the part is sampled to provide a vent hole.

Further, in Japanese Unexamined Patent Publication No. 7-268416, the core powder ratio is measured during blast furnace rest or during operation, and when the powder ratio is 20% or more, heating is required or removal of powder is required. A method has been proposed in which a hollow pipe is inserted from a tuyere in the vicinity of and a hollow vent is provided by sampling coke in the core.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
19, JP-A-6-93320, JP-A-7-
In the method disclosed in Japanese Patent No. 268416, that is, the method of sampling the coke in the core from the tuyere and providing the hollow vent hole in the core, the inside of the core formed by the coke sampling during blast furnace blast There is no guarantee that the hollow vents will be reliably maintained during blow-up.

Therefore, in the method for heating coke, metal, slag in the furnace core or removing coke powder by blowing a part of the high temperature gas into the furnace core through the vent holes of the furnace core as described above, Depending on the state of the vent holes in the core when the air is blown up, the effect may vary.
It is difficult to obtain stable and expected effects. In addition, even if the ventilation holes of the hollow formed in the core by this method are maintained reliably when the air is blown up and the temperature of the core part temporarily rises, ventilation / liquid passage of the core surface layer part Since the root cause of the deterioration of the gas permeability has not been eliminated, there is a high possibility that a region with poor air permeability and liquid permeability will be formed again in the core of the furnace during operation.

In view of the above-mentioned problems of the prior art, the inventors of the present invention have found that the ventilation / liquid-permeability of the furnace core surface layer portion is deteriorated, which causes a decrease in the furnace core temperature particularly during the operation of blowing pulverized coal in a blast furnace. We have developed a technology aimed at fundamentally solving the problem without increasing the fuel ratio as in the past, and have applied for a patent application 2001-040.
I am applying for No. 229. The invention resides in "in the operation of blowing pulverized coal, a method of heating the core by blowing oxygen-containing powder into the blast furnace together with pulverized coal from the tuyere of the blast furnace". Therefore, the present invention has been further developed for the purpose of efficiently carrying out the oxygen-containing powder to the core of the furnace in carrying out the above-mentioned invention.

[0009]

The present invention has been made in order to solve the problems in the above-mentioned conventional method, and the gist thereof is the following means. (1) When the oxygen-containing powder is blown, the oxygen-containing powder is supplied from the inside of the central tube using a triple tube lance, oxygen is supplied between the central tube and the intermediate tube, and nitrogen is supplied between the outer tube and the intermediate tube. Method for blowing oxygen-containing powder from tuyere of blast furnace. (2) When the oxygen-containing powder is blown, the oxygen-containing powder is supplied from the blast furnace tuyere using a double-pipe lance to supply the oxygen-containing powder from the inside of the inner pipe and nitrogen between the inner and outer pipes, respectively. How to blow.

(3) When the oxygen-containing powder is blown in, the speed of nitrogen supplied from the outer tube of the oxygen-containing powder supply pipe is made higher than the speed of heated air in the blow pipe (1).
Alternatively, the method of blowing oxygen-containing powder from the tuyere of the blast furnace according to (2). (4) The method for blowing oxygen-containing powder from tuyere of a blast furnace according to any one of (1) to (3), wherein an inert gas or air is used as a substitute for nitrogen used in blowing the oxygen-containing powder. (5) The method of blowing oxygen-containing powder from a tuyere of a blast furnace according to any one of (1) to (4), in which the oxygen-containing powder is mixed and blown with pulverized coal. (6) The method for blowing oxygen-containing powder from the tuyere of a blast furnace according to (5), wherein the pulverized coal mixed with the oxygen-containing powder and blown therein has a volatile content of 25 mass% or less.

(7) A method for injecting oxygen-containing powder from tuyere of a blast furnace for adjusting and controlling the flow velocity of a gas body supplied from the outer tube portion of a triple-tube lance or a double-tube lance used for blowing oxygen-containing powder. (8) A method for injecting oxygen-containing powder from tuyere of a blast furnace for adjusting and controlling the flow rate of a gas body supplied from the outer tube portion of a triple-tube lance or a double-tube lance used for blowing oxygen-containing powder. (9) A method for injecting oxygen-containing powder from tuyere of a blast furnace for adjusting and controlling the flow velocity and flow rate of a gas body supplied from the outer tube part of a triple-tube lance or a double-tube lance used for blowing oxygen-containing powder.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is premised on a pulverized coal blowing operation method into a blast furnace, and is a method for feeding oxygen-containing powder into a furnace core portion when carrying out the operation method. First, the installation state of the oxygen-containing powder blowing lance is shown in FIG. A tuyere 2 is provided on the furnace wall 1 of the blast furnace, and a blow pipe 3 is connected to the rear end of the tuyere 2. Gas such as heated air is supplied to the blow pipe 3 and is blown from the tuyere 2 into the furnace 4 through the blow pipe 3. In such a blowing tuyere, the lance 7 penetrates the blow pipe 3 and opens into the gas passage, and the oxygen-containing powder is blown into the gas passage through the lance 7. A jet flow 5 of gas is formed in front of 2, and a region where the coke filled in the furnace 4 burns while swirling, that is, a raceway 6 is formed.

Usually, the pulverized coal blown from the tuyere ₂ is the carbon (C) in the coke or the pulverized coal blown in the jet area 5 where SiO ₂ which is the component of Ash contained therein. Since it reacts with the carbon (C) in it to form SiO, the concentration of SiO ₂ in the pulverized coal Ash decreases and A
The l ₂ O ₃ concentration increases relatively. In this way, A
Ash in the pulverized coal having a high l ₂ O ₃ concentration and a high basicity (CaO / SiO ₂ ) adheres to and accumulates in the voids of the coke filling layer 31 at the back of the raceway 6 to form a high melting point and highly viscous dripping slag. Formed, and this becomes a cause of deteriorating ventilation and liquid permeability to the furnace core together with the coke powder. 3 in the figure
0 indicates flying oxygen-containing powder.

Under the above-described oxygen-containing powder blowing condition, after the oxygen-containing powder is blown from the lance 7 into the blast furnace interior 4, the oxygen-containing powder is thermally decomposed inside the jet flow 5 depending on the composition of the oxygen-containing powder. Oxygen-containing powder may disappear or decrease before it reaches the furnace core due to melting and reaction.
Therefore, when the oxygen-containing powder is blown into the raceway in order to reach the deep inside of the raceway in a high temperature atmosphere when the oxygen-containing powder is blown. Next, it was examined based on the view that it is most important not to eliminate or reduce the amount.

That is, how to cut off the oxygen-containing powder flying inside the raceway from the high temperature atmosphere, suppress the occurrence of the above-mentioned phenomenon as much as possible, and make the oxygen-containing powder reach the core of the furnace as much as possible. As for As a result, an inert gas such as nitrogen is supplied at the same time as the oxygen-containing powder is blown, and a curtain-shaped gas barrier film that wraps the oxygen-containing powder from the periphery is formed by the gas flow. It was found that the oxygen-containing powder can be transported to the core of the raceway by controlling the contact between the oxygen-containing powder and the outside atmosphere and adjusting the flow rate of this gas.

Therefore, in the present invention, due to the effect of the nitrogen gas described above, the decrease of the oxygen-containing powder in the raceway can be suppressed, so that the oxygen-containing powder reaches the intended furnace core. be able to. Although various methods of blowing oxygen-containing powder are conceivable, the method considered by the present inventors to be appropriate is as described in the means for solving the above-mentioned problems.

Next, the method of the present invention will be described with reference to the drawings. First, there is a method of using a triple pipe lance 8, and as an embodiment thereof, a sectional view and a side view of the lance are shown in FIGS. 2 (a) and 2 (b), respectively. Powder, nitrogen, and oxygen are simultaneously blown in. That is, in the lance 8, the intermediate pipe 11 is inserted inside the outer pipe 10, and the central pipe 12 is inserted inside the intermediate pipe 11.
It has a triple tube structure in which is inserted, and the gas body flow path has three passages, which is a feature. Between the intermediate tube and the outer tube (outer tube portion) 17, nitrogen is supplied so that carbon in the oxygen-containing powder can be supplied from each passage.
Appropriate amount of oxygen to be consumed by hydrogen (some oxygen-containing powders contain combustion components) and nitrogen that suppresses contact with the atmosphere of the oxygen-containing powder in the raceway as much as possible It is supplied at a constant flow rate.

The second method is to use a double tube lance 9, and FIGS. 3 (a) and 3 (b) show a sectional view and a side view of the lance, respectively. That is, the lance 9 has a double tube structure in which the inner tube 21 is inserted inside the outer tube 20 and has two gas body passages, and the oxygen-containing powder is supplied from the inside 25 of the inner tube. From between the inner pipe and the outer pipe (outer pipe portion) 26, nitrogen is supplied at an appropriate flow rate to suppress contact of the oxygen-containing powder with the atmosphere in the raceway as much as possible.

In the above, the method of using nitrogen in order to isolate the oxygen-containing powder from the atmosphere inside the raceway as much as possible when carrying the oxygen-containing powder to the coke powder depositing portion of the furnace core at the back of the raceway has been described. However, inert gas or air can be considered as an alternative to nitrogen. In the case of air, it is predicted that cold air (atmosphere) will be more effective in blocking the atmosphere inside the raceway.

Further, since the blast speed supplied to the blast furnace through the blow pipe is usually at most 250 m / sec,
Nitrogen gas needs to be considered so as to maintain a flow velocity having a higher velocity. Further, in the lance, in order to maintain the flow velocity of the nitrogen gas at a high speed, the tip of the nitrogen supply port has a throttle structure 13, and the length of the throttle portion is up to a predetermined distance in a laminar flow state of the nitrogen gas flow. It is necessary to give the length that can be reached. In this case, it is also necessary to previously design the passage interval so that the lance tube itself allows the nitrogen gas to flow in a laminar flow and keep the shape. In any case, it is essential to form a gas curtain of nitrogen gas to suppress the disappearance or decrease of the oxygen-containing powder in the raceway as much as possible.

Further, the oxygen-containing powder is adjusted by adjusting the flow rate and / or the flow rate of the nitrogen gas or its substitute gas supplied from the outer tube of the oxygen-containing powder blowing lance (double tube or triple tube). Since it is possible to freely adjust the combustion focal length from the tip of the blast furnace tuyere in the raceway due to the combustion of the body, the state of the core at the time of carrying out the present invention,
Alternatively, it is easy to adjust and control the position of the highest temperature point due to the combustion of the oxygen-containing powder in the raceway depending on the condition of the furnace.

That is, if the maximum temperature position within the raceway is to be located as far away from the tuyere tip as possible, the flow velocity or flow rate of the gas body from the outer lance tube is increased. It is possible to reach the goal easily. Although the composition of the oxygen-containing powder was not particularly mentioned, all of the oxygen-containing powders described in Japanese Patent Application No. 2001-040229, which is the invention of the present inventors, can be applied.

FIG. 4 shows an example of the present invention in which nitrogen was added during the blowing of oxygen-containing powder, together with a conventional example and a comparative example. (A) is the conventional pulverized coal only, and (b) is this. In addition to the above, the oxygen-containing powder is blown (Comparative Example), and (c) is the blow with the gas curtain (present invention) in (b) added. It is clearly seen from the figure that the high temperature region in the blast furnace raceway is gradually shifted to the furnace core side from a to c due to the difference in the blowing means (difference between a, b and c). In the above description, the blowing of the oxygen-containing powder was mainly described, but in the present invention, the same effect can be obtained by mixing and blowing the oxygen-containing powder with pulverized coal or other carbonaceous material. Even if the substance to be blown is not only the oxygen-containing powder alone, it can be sufficiently applied.

The pulverized coal mixed with the oxygen-containing powder and blown therein preferably has a volatile content of 25% by mass or less, and the combustion position of the pulverized coal in the raceway is toward the furnace core side. As it migrates, it helps the oxygen-containing powder reach the furnace core. Further, as carbonaceous materials other than pulverized coal, coke dust, toner waste materials, unburned char generated during gasification of coal, carbonaceous material generated during biomass treatment, etc. are considered. It is easy for the body to reach the core.

[0025]

EXAMPLES Examples in which the effects of the present invention are applied to an actual blast furnace will be described below. The tip of each of the oxygen-containing powder blowing lances used in the examples is 20 mm from the tuyere tip.
It was installed near the tip of the tuyere inside. (Example 1) An example in which an oxygen-containing powder (oxygen-containing waste plastic powder) was blown in using a triple tube lance as shown in FIG. 2 in a blast furnace of 3280 m ³ using the method of the present invention will be described. Amount of oxygen-containing powder blown in is 10 kg / t-pig
(Hereinafter, t-pig is simply referred to as tp), nitrogen is simultaneously supplied from the same lance at a flow rate of 220 m / sec at a flow rate of 5 m ³ / h /
(1 tuyere) Blows in and also oxygen is 3m ³ / h /
(1 tuyere) was blown from the same lance. as a result,
Compared with the conventional method, the arrival rate of oxygen-containing powder to the furnace core was improved, and the decrease rate of the powder rate was reduced by 20%.

Example 2 Using the method of the present invention, 3280
An example in which a double tube lance as shown in FIG. 3 is used in a m ³ blast furnace and nitrogen is added at the time of blowing oxygen-containing powder (manganese dioxide powder) will be described. The amount of oxygen-containing powder blown in is 8 kg / tp, and at the same time nitrogen flow rate is 2 from the same lance.
6 m ³ / h / (1 tuyere) was blown at 60 m / sec. As a result, the arrival rate of the oxygen-containing powder to the core of the furnace was improved compared to the conventional method, and the powder rate was reduced by 15% as compared with that before the implementation.

Example 3 Using the method of the present invention, 3280
An example in which a triple tube lance as shown in FIG. 2 is used in a m ³ blast furnace and air is added instead of nitrogen when the oxygen-containing powder is blown will be described. 4. The amount of oxygen-containing powder (oxygen-containing waste plastic powder) blown in is 12 kg / tp, and at the same time air at room temperature is flown from the same lance at a flow rate of 240 m / sec.
5m ³ / h / (1 tuyere) blown in and oxygen 4m ³
/ H / (1 tuyere) was blown. As a result, the arrival rate of the oxygen-containing powder to the furnace core was improved compared to the conventional method, and the powder rate was reduced by 20% as compared with that before the implementation.

(Embodiment 4) Using the method of the present invention, 3280
Using a double tube lance as shown in Fig. 3 in an m ³ blast furnace, oxygen-containing powder (manganese dioxide powder) and pulverized coal with a volatile content of 18% by mass are mixed and blown, and nitrogen is added at the time of blowing. An example will be described. The amount of oxygen-containing powder blown is 10
kg / t ・ p, pulverized coal injection rate is 150 kg / t ・
It was p. At the same time, the flow rate of nitrogen from the same lance is 250 m.
8 m ³ / h / (1 tuyere) was blown in at / sec. As a result, the arrival rate of the oxygen-containing powder to the furnace core was improved as compared with the conventional method, and the powder rate was reduced by 35% compared to that before the implementation.

[0029]

According to the present invention, the nitrogen gas, the inert gas or the air is used as the gas curtain when the oxygen-containing powder is simultaneously blown in the pulverized coal blowing operation. I was able to carry it all the way to the back of the raceway while maintaining that condition while suppressing the disappearance or decrease in the car. In addition, the present invention can use a gas that is easily available and inexpensive, and is easy to carry out, so that it has a beneficial effect on the operation of the blast furnace.

[Brief description of drawings]

FIG. 1 is a schematic view showing a cross section of a tuyere used for blowing air into a blast furnace.

FIG. 2 is a view showing a cross section of a triple pipe lance used in the present invention.

FIG. 3 is a view showing a cross section of a double pipe lance used in the present invention.

FIG. 4 is a diagram showing movement of a high temperature region within a raceway due to a difference in blowing means.

[Explanation of symbols]

1 Blast furnace wall 2 tuyere 3 blow pipe 4 inside the furnace 5 jets 6 raceways 7 Lance 8 Triple tube lance 9 Double pipe lance 10 outer tube 11 Intermediate tube 12 Central tube 13 Tube tip restriction 15 Inside the central tube 16 Between central pipe and intermediate pipe 17 Between middle pipe and outer pipe 20 outer tube 21 inner tube 25 Inside the inner tube 26 Between inner pipe and outer pipe 30 Oxygen-containing powder in flight 31 Coke packed bed

Claims (9)

[Claims] 1. When blowing oxygen-containing powder, a triple-tube lance is used to introduce the oxygen-containing powder from the inside of the central tube, oxygen between the central tube and the intermediate tube, and nitrogen between the outer tube and the intermediate tube. A method for injecting oxygen-containing powder from the tuyere of a blast furnace, characterized by supplying each of them. 2. A blast furnace blade characterized in that, when the oxygen-containing powder is blown, the oxygen-containing powder is supplied from the inside of the inner pipe and nitrogen is supplied from between the inner pipe and the outer pipe by using a double pipe lance. Method of blowing oxygen-containing powder from the mouth. 3. When blowing the oxygen-containing powder, the velocity of nitrogen supplied from the outer pipe of the oxygen-containing powder supply pipe is set to be higher than the velocity of heated air in the blow pipe. The method for blowing oxygen-containing powder from the tuyere of a blast furnace according to claim 2. 4. The blast furnace tuyere according to claim 1, wherein an inert gas or air is used as a substitute for nitrogen used when the oxygen-containing powder is blown. Method for blowing oxygen-containing powder. 5. The oxygen-containing powder from the tuyere of the blast furnace according to claim 1, wherein the oxygen-containing powder is mixed with pulverized coal or another carbonaceous material and then blown. Powder injection method. 6. The oxygen-containing powder blown from the tuyere of the blast furnace according to claim 5, wherein the pulverized coal mixed and blown with the oxygen-containing powder has a volatile content of 25% by mass or less. Method. 7. The oxygen-containing powder from the tuyere of the blast furnace, characterized in that the flow velocity of the gas body supplied from the outer tube portion of the triple-tube lance or the double-tube lance used when blowing the oxygen-containing powder is adjusted and controlled. Body blowing method. 8. An oxygen-containing powder from a tuyere of a blast furnace, characterized by adjusting and controlling a flow rate of a gas body supplied from an outer tube portion of a triple-tube lance or a double-tube lance used for blowing oxygen-containing powder. Body blowing method. 9. A method for controlling the flow velocity and flow rate of a gas body supplied from the outer tube part of a triple tube lance or a double tube lance used for blowing oxygen-containing powder, wherein the content from the tuyere of the blast furnace is controlled. Oxygen powder blowing method.