JP6504129B2 - Blast furnace operation method - Google Patents

Description

  The present invention relates to a blast furnace operation method.

  In recent years, in order to reduce the amount of coke used in a blast furnace, a method of operating a blast furnace in which a reducing material such as pulverized coal or a flammable reducing gas (natural gas, coke oven gas, etc.) is blown from a tuyere has been put into practical use. In a method of operating a blast furnace using pulverized coal or a flammable reducing gas, pulverized coal or a flammable reducing gas is supplied to the blast furnace together with the hot air through a blow pipe for supplying the hot air into the blast furnace.

  The blow pipe is provided with a blowing lance for blowing a material into the blow pipe, and the pulverized coal and the flammable reducing gas are blown into the hot air flowing in the blow pipe through the blowing lance. It has become. The pulverized coal and the flammable reducing gas function as a substitute for coke by being burned in a combustion space called a raceway in the blow pipe and the blast furnace.

  In order to greatly reduce the amount of coke used, efficient combustion and gasification of pulverized coal in a raceway is important. On the other hand, when the amount of pulverized coal blowing is increased, unburned pulverized coal intrudes into the furnace to cause a problem of deterioration of the blast furnace furnace condition.

  For this reason, various technologies have been developed to gasify as much pulverized coal as possible in the raceway while keeping the furnace conditions stable in the blast furnace and to lead to the reduction of the coke ratio.

  For example, in Patent Document 1, a lance for blowing a reducing material from a tuyere to promote combustion of pulverized coal in a raceway is a double pipe, and LNG is blown from one of the double pipe lances, and the other is A blowing method has been proposed, in which the combustion temperature of the raceway can be greatly increased by blowing pulverized coal, and the deformation of the lance can be prevented by setting the outlet speed of the outer pipe to 20 to 120 m / s. ing.

  Further, according to Patent Document 2, a gas reducing material or a liquid reducing material is blown into the blast furnace using high-crystal water ore from the tuyere so that the amount of hydrogen input to the blast furnace and tuyere falls within an appropriate range. A method has been proposed which can be used in blast furnaces while suppressing reduction and reduction of highly crystalline water ore.

  According to Patent Document 3, when the tar / heavy oil is blown into the blast furnace, the burning rate of the tar / heavy oil can be kept sufficiently high even under the condition where the hot air temperature is relatively low by blowing the gas fuel into the vicinity. A method that can be done is proposed.

  In the patent document 4, the tuyere pressure loss is reduced by blowing in the auxiliary fuel having good combustibility to the tuyere blowing reducing materials having different flammability such as pulverized coal, C heavy oil and coke oven gas from the inside of the furnace. A method has been proposed to keep the reactor condition deterioration equally.

JP, 2013-19007, A Patent No. 4759977 Japanese Patent Application Laid-Open No. 62-238307 JP-A-4-247818

The method of Patent Document 1 is an excellent method which can promote the temperature rise of the pulverized coal and keep the combustibility of the pulverized coal at a high level by simultaneously blowing in the flammable reducing gas together with the pulverized coal. In this method, the heat load on the lance is large, and the wear of the lance is a concern. Therefore, Patent Document 1 adopts a method of suppressing the wear of the lance by cooling the lance by setting the gas flow velocity of the outer tube to 20 m / s or more.
However, when the method of Patent Document 1 was carried out, it was found that the lance receives a thermal load depending on the conditions. Then, when it investigated in detail, when combustion of the pulverized coal was stable, the lance was not worn out and was very good, but when the combustion of the pulverized coal became unstable and the flame fluctuated, it was instantaneously strong It was found that wear of the lance occurred while receiving heat radiation.
That is, it turned out that the method of patent document 1 is not necessarily a sufficient method from a viewpoint of lance wear suppression.

  Moreover, the method of blowing in a liquid reducing material as a tuyere blowing and reducing material is proposed by patent document 2, 3, 4. However, in Patent Documents 2, 3 and 4, no consideration is given to the flammability and loss of lance when co-blowing pulverized coal and liquid reducing agent, and in principle these methods have sufficient lance protection. It is difficult to say that I can keep it.

  The present invention has been developed in consideration of the combustion state of pulverized coal in a blast furnace to solve the above-mentioned problems, and its summary constitution is as follows.

1. In a blast furnace operation method in which a solid reducing material and a liquid reducing material are simultaneously blown into the blast furnace from a blast furnace tuyere having a tuyere blowing lance, a multi-tube lance is used as the lance, and innermost and outermost tubes of the multitube lance are used. A blast furnace operation method characterized in that a solid reducing material is blown from one side and a liquid reducing material is blown from the innermost pipe or the outermost pipe of the multi-tube lance which is not blowing the solid reducing material.

2. 3. A blast furnace operation method comprising using a double pipe lance as the tuyere blowing lance in the above 1, and injecting a solid reducing material from the inner pipe and a liquid reducing material from the outer pipe.

3. In 1 and 2 above, when the blow rate unit of the liquid reducing material is LR (kg / t), the solid reducing material ratio is PCR (kg / t), and the volatile matter mass ratio in the solid reducing material is VM, these are , The following equation (1)
0.0060 <LR / {PCR × (1-VM)} (1)
The blast furnace operation method characterized by blowing in a liquid reducing agent on the conditions which satisfy | fill the relationship of (1).

4. In 1, 2 or 3, when the blow rate unit of the liquid reducing material is LR (kg / t), the solid reducing material ratio is PCR (kg / t), and the volatile matter mass ratio in the solid reducing material is VM, These are following Formula (2)
LR + PCR VM <110.0 (kg / t) ... (2)
The blast furnace operation method characterized by blowing in a liquid reducing agent on the conditions which satisfy | fill the relationship of (1).

According to the present invention, the blowout lance of the tuyere is a multiple tube, and the solid reducing material is blown from one of the innermost and outermost tubes of the multitube lance, and the multiple tube lance is not blowing such solid reducing material. Since the liquid reducing material is blown in from the innermost pipe and the outermost pipe, the lance can be strongly cooled by the strong cooling effect by the liquid contact, and as a result, the wear of the lance can be effectively suppressed. .
In addition, since the liquid reducing material burns faster than the solid reducing material, the early burning flame of the liquid reducing material accelerates the temperature rise of the solid reducing material by blowing it simultaneously with the solid reducing material according to the present invention. An improvement in the burn rate of the reducing material can also be achieved.

It is a schematic diagram of the pulverized coal combustion experimental furnace used in the Example. It is a principal part enlarged view of FIG.

Hereinafter, the present invention will be specifically described. In addition, the case where a double pipe lance is used as a multi-tube lance, and pulverized coal is used as a solid reducing material will be described.
In recent years, the combustibility of pulverized coal has been improved by various technological developments, so combustion of pulverized coal has come to occur immediately after injection by lance. However, the combustion site of pulverized coal is not always stable, and the flame becomes unstable particularly under the condition of high pulverized coal ratio. At this time, extremely large heat radiation may be emitted instantaneously according to the fluctuation of the combustion flame of pulverized coal.

Therefore, even if a lance having a cooling capacity sufficient to withstand the average heat load is used, the instantaneous large heat load may cause wear of the lance.
Therefore, in order to prevent lance wear and tear in the high-combustible pulverized coal blowing operation, a blowing method that takes into consideration both the stability of the combustion flame and the cooling capacity is required.

  Therefore, in the present invention, the blowing lance is a double pipe, and preferably the liquid reducing material is allowed to flow through the outer pipe. Since the liquid reducing material is still in the liquid state in the lance, the heat transfer coefficient with the lance wall is high, and it exhibits a very strong cooling effect. Therefore, a better lance wear suppression effect can be obtained as compared with the method in which the lance cooling ability is secured by flowing a gas through the lance as in Patent Document 1.

  By the way, the destabilization of the pulverized coal combustion flame is caused by the unburned char and ash which can not be burned in the raceway deteriorating the air permeability of the raceway end and the core. In addition, since volatile matter volatilizes and burns in a relatively short time, pulverized coal with higher volatile matter content has less unburned char and the combustion flame becomes stable. In other words, as the amount of char or ash blown into the tuyere increases, the flame becomes unstable, and a strong heat radiation is generated momentarily to cause the lance wear and tear. On the other hand, since the liquid reducing agent has the effect of cooling the lance, the more the amount of the liquid reducing agent injected, the more the loss of the lance is suppressed.

The total amount of char and ash blown into the tuyere is PCR (1-VM) [kg / t], where the pulverized coal ratio is PCR (kg / t) and the volatile matter mass ratio in pulverized coal is VM. Is represented by Therefore, assuming that the blowout unit of the liquid reducing material is LR (kg / t), the larger the ratio of LR to PCR (1-VM), that is, the larger the value of LR / {PCR × (1-VM)}, the lance It can be considered that the effect of suppressing wear and tear is high.
As described above, if the value of LR / {PCR × (1-VM)} is sufficiently large, lance wear and tear can be suppressed, but if the value of LR / {PCR × (1-VM)} becomes 0.0060 or less, the flame Since the instantaneous radiant heating derived from the instability becomes larger than the cooling effect of the liquid reducing agent, there is a possibility that the lance wear may occur.
Therefore, when blowing the liquid reducing material, when the blowing unit of the liquid reducing material is LR (kg / t), the pulverized coal ratio is PCR (kg / t), and the volatile matter mass ratio in pulverized coal is VM, These are the following equation (1)
0.0060 <LR / {PCR × (1-VM)} (1)
It is advantageous to blow in the conditions which satisfy the relation of.

In addition, when a large amount of the liquid reducing material is blown into the furnace, it becomes a soot from the top of the furnace and is not effectively used as the reducing material, and conversely, the ratio of the reducing material is increased. Since the soot tends to be generated if oxygen is insufficient when the liquid reducing material burns, under the condition that the liquid reducing material is blown simultaneously with the pulverized coal as in the present invention, oxygen deficiency further progresses and soot is generated. It becomes an easy environment. Although the char component of pulverized coal burns slower than the liquid reducing material, it does not affect the oxygen deficiency of the liquid reducing material, but the volatile matter competes with the burning of the liquid reducing material because it burns quickly, and the liquid reducing material burns Cause oxygen deficiency.
Therefore, in order to prevent the generation of soot, it is preferable to operate so that the total amount of the liquid reducing material and the volatile matter is less than or equal to a specified value.

Then, when the inventors examined this point, LR (kg / t), the pulverized coal ratio was PCR (kg / t), the volatile matter mass ratio in pulverized coal was VM, and the blowout unit of the liquid reducing material was LR and kg. When they are given by the following equation (2)
LR + PCR VM <110.0 (kg / t) ... (2)
It has been found that the generation of soot is avoided if the liquid reducing agent is blown in under the conditions satisfying the relationship of
On the other hand, under the condition that LR + PCR · VM is 110.0 kg / t or more, soot is generated from the top of the furnace, blowing utilization efficiency of the reducing material is deteriorated, and the reducing material ratio is increased.

The multi-tube lance according to the present invention includes double-tube lances, triple-tube lances, quadruple-tube lances, and the like, and further includes parallel lances.
Further, in the present invention, as the solid reducing material, in addition to pulverized coal, charcoal, wood waste, solid waste fuel, etc. can be considered. Furthermore, as the liquid reducing material, any material may be used as long as it is a liquid at normal temperature and causes a combustion reaction with oxygen. For example, heavy oil, light oil, tar, rapeseed oil, gasoline etc. can be considered.

  In addition, the liquid reducing material is slower in ignition than the gas reducing material such as natural gas, but is faster than the solid reducing material. For this reason, since the liquid reducing material burns earlier than the solid reducing material, there is also an effect of promoting the temperature rise of the solid reducing material and improving the combustion rate of the solid reducing material. Here, in order to extract the combustion promoting effect of the solid reducing material, it is advantageous to blow in the liquid reducing material at 1 kg / t or more.

Using the pulverized coal as the solid reducing material, a pulverized coal combustion experimental furnace as shown in FIG. 1 was used to carry out the verification experiment described below under the conditions simulating the actual aircraft tuyere. In the experiment, a double tube lance was used as a multiple tube lance. In addition, pulverized coal was investigated from the inner pipe of the double pipe lance, and a liquid reducing agent was injected from the outer pipe. In FIG. 2, the principal part of FIG. 1 is expanded and shown. In the figure, the code | symbol 1 is a double pipe lance, 2 shows the liquid reducing material which blows in the pulverized coal which blows in from a lance inner pipe, and 3 blows out from a lance outer pipe. Further, 4 is a blow pipe, 5 is a coke filling tank, and 6 is an exhaust gas.
In the experiment, the pulverized coal ratio was equivalent to 180 kg / t (60 kg / h in the experimental furnace). In addition, heavy oil was used as the liquid reducing agent. Pulverized coal was used in three experiments shown below, using three types of volatile fraction different.

[Experiment 1] Pulverized coal with a volatile content ratio of 0.19 Using a pulverized carbon with moderate volatile content (VM = 0.19), a test was conducted to gradually increase the amount of liquid reducing material blowing as shown in Table 1. went. In Table 1, pulverized coal ratio PCR (kg / t), liquid reducing agent ratio LR (kg / t), pulverized coal volatile matter ratio VM (-), and LR / {PCR × (1) in each condition -VM)} and LR + PCR · VM are shown. In addition, about liquid reduction agent ratio LR, a test furnace flow rate and an actual machine equivalent value are shown collectively.
Table 1 also shows the results of the combustion test conducted in the pulverized coal combustion experimental furnace under these conditions.

  When the lance after the experiment was examined, as shown in Table 1, under the condition (LR / {PCR x (1-VM)} = 0) where the liquid reducing agent was not injected, the lance received a large heat load. Although the damage mark was seen, when the liquid reducing agent was blown in a certain amount or more (LR / {PCR x (1-VM)}> 0.0060), no damage mark was found in the lance. Further, when the blowing amount of the liquid reducing material was further increased, when the amount reached 80 kg / t (at this time, LR + PCR × VM = 114.2 kg / t), spouting of soot from the coke packed bed was observed .

[Experiment 2] Pulverized coal with a volatile content ratio of 0.03 A similar experiment was attempted using pulverized coal with low volatile content (VM = 0.03). The conditions and results at that time are shown in Table 2. At this time, the combustion flame was somewhat unstable, and strong thermal radiation was occasionally observed.

  When the state of lance after the experiment was examined, as shown in Table 2, under the condition (LR / {PCR x (1-VM)} = 0 and 0.0057) where the blowing amount of the liquid reducing material is small, heat was applied to the lance. Although the damage mark which received load was seen, there was no damage of lance in the conditions (LR / {PCR x (1-VM)} = 0.1115) which increased the flow rate of liquid reductant. Moreover, in this experiment, since all the conditions satisfy | fill the conditions (LR + PCRxVM <110.0 kg / t) of eyelid development suppression, the balloon's blowout from the packed bed was not observed as expected.

[Experiment 3] Conditions of high volatile content pulverized coal A similar experiment was attempted using pulverized carbon of high volatile content (VM = 0.39). The conditions and results at that time are shown in Table 3.

  In this experiment, all conditions satisfied LR / {PCR x (1-VM)}> 0.0060, so when the condition of lance was examined after the experiment, as shown in Table 3, all the lances were healthy. Yes, it was confirmed that the lance did not wear out. In addition, when the liquid reducing agent blowing amount was increased, generation of soot from the packed bed was observed at 40 kg / t (at this time, LR + PCR · VM> 110.2 kg / t).

[Experiment 4] In the same manner as in Experiment 1, except that the blowing of the pulverized coal and the liquid reducing material from the double tube lance is reversed, the lance damage and the occurrence of soot in the blast furnace operation are investigated. However, even in this case, the same result as in Experiment 1 could be obtained.

  From the above-mentioned [Experiment 1]-[Experiment 4], it was confirmed that by simultaneously injecting the liquid reducing material and pulverized coal under the preferable conditions according to the present invention, it is possible to suppress the wear of the lance and the generation of wrinkles together. .

Reference Signs List 1 double pipe lance 2 pulverized coal blown from the lance inner pipe 3 liquid reducing material blown from the lance outer pipe 4 blow pipe 5 coke filled tank 6 exhaust gas

Claims (3)

In a blast furnace operation method in which a solid reducing material and a liquid reducing material are simultaneously blown into the blast furnace from a blast furnace tuyere having a tuyere blowing lance,
The multi-tube lance is used as the lance, and one of the innermost and outermost tubes of the multi-tube lance has a solid reducing agent having a volatile content ratio of 0.19 or less, and the other is not the solid reducing agent Liquid reductant from the innermost or outermost pipe of the pipe lance ,
Let LR (kg / t) be the blow rate unit of the liquid reducing material, PCR (kg / t) be the solid reducing material ratio, and VM be the mass ratio of volatile matter in the solid reducing material. (1)
0.0060 <LR / {PCR × (1-VM)} (1)
On the condition that satisfies
The blast furnace operation method characterized by blowing in each. According to claim 1, wherein the tuyere blowing using a double tube lance as the lance, the solid reducing material from the inner tube, blast furnace operation wherein the blowing said than the outer tube the liquid reducing agent, respectively. According to claim 1 or 2, the blowing intensity of the liquid reducing agent LR (kg / t), the solid reducing material ratio PCR (kg / t), and the volatiles mass ratio in the solid reducing material VM When these are the following equation (2)
LR + PCR VM <110.0 (kg / t) ... (2)
A blast furnace operation method comprising blowing the solid reducing material and the liquid reducing material under the condition satisfying the following relationship:

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