JPH07126642A - Blast furnace coke manufacturing method - Google Patents

Abstract

(57) [Summary] [Purpose] When coal was carbonized in a coke oven to produce blast furnace coke, the carbonization temperature was lowered and the carbonization time was shortened for reasons such as improving the productivity of the coke oven. Coke quality is restored with a dry fire extinguisher (CDQ). [Composition] During dry fire extinguishing treatment of coke whose dry distillation temperature is lower than 900 ° C, red hot coke is charged through a disperser installed at the upper entrance of the fire extinguishing equipment, and the red hot coke contains combustible gas. A method for producing coke for a blast furnace, which comprises blowing hot air produced by combustion of a circulating gas for heat exchange in a dry fire extinguisher to reheat red hot coke to a temperature higher than the carbonization temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a blast furnace coke by carbonizing carbon in a coke oven to improve the quality of coke in a dry fire extinguishing facility (hereinafter referred to as CDQ).

[0002]

2. Description of the Related Art A general coke manufacturing method comprises the following steps. Up to a coal storage tank called a coal tower installed on the furnace of a coke oven, which is prepared by mixing several or about 10 types of raw coal having a water content of 8 to 10% in a predetermined ratio and a predetermined particle size Carry on a belt conveyor.
Coal equivalent to one kiln of a coke oven (hereinafter referred to as “charging coal”) is weighed from the coal storage tank and delivered to a coal car. The coal car runs over a furnace to a predetermined kiln, and the entire amount of charged coal loaded from a coal charging port of 4 to 5 holes provided on the furnace of the coke furnace is charged into the carbonizing chamber. Charging coal is indirectly heated from the combustion chambers on both sides through the brick walls of the carbonization chamber, and carbonized to about 1000 ° C for about 24 hours. After that, it was discharged outside the furnace as coke,
It is charged into a fire extinguishing facility, where it is extinguished by wet cooling with water sprinkling or dry cooling with an inert gas to obtain blast furnace coke.

Since the coke oven is operated at a very high temperature in this way, a large amount of energy, for example, the amount of heat of about 500 to 600 kcal is necessary for carbonizing 1 kg of coal. Since the reduction of the input energy brings about the improvement of the economical efficiency, that is, the reduction of the coke manufacturing cost, the heat source has been conventionally effectively used such as charging the preheated coal and recovering the heat. On the other hand, technological developments have been made to lower the carbonization temperature, shorten the carbonization time, and reduce the input energy.

However, the lowering of the carbonization temperature means the quality of coke.
(Strength, reactivity) decrease. Figure 1 shows the change in coke strength with respect to the carbonization temperature. Strength is JIS K2151
Rotational strength index DI ₁₅ ¹⁵⁰ specified in 6.3 of 1
5 mm index). It can be seen that the strength is constant above the dry distillation temperature of 950 ℃, but linearly decreases with the temperature decrease below 900 ℃. That is, when the same raw coal is used, the strength of the coke produced is inevitably decreased with the decrease of the carbonization temperature, and therefore, 900 ℃
In order to use the following coke that has been carbonized at medium temperature for blast furnaces that require high quality, it is essential to make some efforts.

The conventional coke having a dry distillation temperature of about 950 ° C. or higher is discharged from a high temperature dry distillation coke and the coke of about 900 ° C. or lower from a medium temperature dry distillation coke or a coke oven.
It is called red hot coke when it has heat.

As an example, there is a method of improving the coke quality by upgrading the blended raw material, but this is not preferable because it causes a large increase in raw material cost. As described above, in the production of coke that requires high quality, it is difficult to significantly lower the carbonization temperature.

In order to solve such a problem, Japanese Patent Laid-Open No. 63-8480
In the gazette, medium-temperature dry-distilled coke discharged from a coke oven is charged into a CDQ, and at the same time, hydrocarbon compounds such as tar are blown into the CDQ at the same time, so that pyrolytic carbon is vapor-deposited on the red hot coke to obtain coke quality. Techniques for improving the are disclosed. Although the coke quality is certainly improved by this method, the added tar does not completely react, and unreacted tar is mixed in the heat exchange circulation gas and introduced into the boiler side, where it is cooled and condensed. It will adhere to pipes and the like, and as a result, various troubles will be induced.

Further, Japanese Patent Application Laid-Open No. 2-194087 discloses a method in which air is blown into a pre-chamber, oxygen in the air is reacted with a gas mainly generated from coke, and the temperature is raised by the heat of reaction. . This method is very simple and attractive in terms of equipment, but this is a test using coke from a 1/4 ton batch coke oven and a steel box, which is the subject of the present invention. The batch is about 30 tons and cannot be used when CDQ is used.

The problem in this case is whether or not the air and the gas are in sufficient contact with each other. That is, in the method of the known example, the gas generated from the coke flows substantially upward and the air flows substantially downward, so that the air and the gas contact and burn.

However, in the CDQ which is the object of the present invention, since the gas is finally guided to the flue, both the air and the gas generated from the coke basically flow downward in the prechamber. In such a flow, it is very questionable whether the air and the gas are in sufficient contact with each other and burned to uniformly heat the coke.

That is, in actual CDQ, it is highly likely that the air first comes into contact with the coke on the upper layer surface, and in this case, almost all the amount of oxygen in the air instantaneously reacts with the carbon in the coke. When this reaction occurs, the following problems occur.

The coke on the surface of the top of the CDQ furnace burns out.・ Only coke in the area where air is blown locally burns and local heating occurs. As described above, when air is introduced into the CDQ, which is the object of the present invention, a rapid combustion reaction with coke occurs, the risk of wastefully burning out the product coke, and the risk of causing local heating are extremely high. Since it becomes large, it is difficult to apply it to the actual process.

[0013]

DISCLOSURE OF THE INVENTION An object of the present invention is to reduce the carbonization temperature for economical reasons such as productivity improvement of the coke oven when carbonizing carbon in the coke oven to produce coke for blast furnace. We provide a method to improve the coke quality by recovering the coke quality that has deteriorated due to the shortening of the carbonization time by efficiently reheating the red hot coke in a dry fire extinguishing facility (CDQ) and recovering it to the level of high temperature carbonization coke. That is. As a result, even in the production of blast furnace coke, which requires high quality, it is possible to lower the carbonization temperature and the carbonization time.

[0014]

[Means for Solving the Problems] The present inventors have examined various problems concerning a method for improving the quality of medium temperature carbonization coke by CDQ. As a result the coke CD by the disperser
It was found that the coke quality can be improved by adjusting the particle size distribution in the radial direction in the Q and blowing the low-reactivity hot air generated by the combustion of the circulating gas for heat exchange in the CDQ containing combustible gas into the red hot coke. The method of the present invention has been completed, which is economical and can exert remarkable effects without causing troubles in the apparatus.

That is, the gist of the method of the present invention is that during the dry fire extinguishing treatment of the red hot coke discharged from the coke oven, the red hot coke is charged through a disperser installed at the upper entrance of the fire extinguishing equipment, and the red hot coke is charged. A method for producing coke for a blast furnace, which comprises blowing hot air generated by combustion of a circulating gas for heat exchange in a dry-type fire extinguishing equipment containing a combustible gas into the coke to reheat the red hot coke to a temperature above the carbonization temperature.

More preferably, in the above method, the dry distillation temperature of the red hot coke charged into the dry fire extinguishing equipment in the coke oven is lower than the average dry distillation temperature of 900 ° C.

The coke, the quality of which has been improved by the method of the present invention, is then contacted with the circulating gas for heat exchange in the cooling section in the CDQ to perform heat exchange by a known method.
It will be cooled below 0 ° C, and finally it will be extracted from the bottom of CDQ. On the other hand, the hot circulating gas is introduced into the boiler, where it is heat-exchanged and cooled, and then circulated again below the CDQ. Further, a part of the circulating gas is burned to reheat the coke as a reheating gas (hot air).

[0018]

The function and effect of the constituent elements will be described in detail below. About the disperser Since the red hot coke charged to the CDQ generally has a wide particle size distribution, particle size segregation occurs depending on the charging method.
It affects the passage of heating or cooling gas and thus the temperature distribution of red hot coke in the CDQ.

In a typical case where there is no disperser or the like, the coke charged from above deposits in a mountain shape. In this case, the coke having a larger grain size is more likely to roll down the slope of the mountain, and thus is more likely to be deposited on the outer peripheral portion far from the center, and on the contrary, the coke having a smaller grain size is unevenly distributed in the central portion. Therefore,
Inside the CDQ, fine grain coke is deposited near the center, and coarse grain coke is mainly deposited on the outer periphery.

In this case, since the outer peripheral portion has a lower ventilation resistance, the reheating gas introduced from the upper portion of the CDQ tends to flow to the outer peripheral portion, while the fine coke is segregated to have a higher ventilation resistance than the surroundings. The phenomenon that gas does not flow easily in the part occurs. This reheating gas flows from the upper part to the lower part of the pre-chamber part, then merges with the heat exchange circulating gas rising from the lower part in the central part and is extracted from the CDQ central outer peripheral part to the flue. It will be. In this way, the reheating gas will eventually flow to the outer peripheral portion. Therefore, when it is easy to flow in the outer peripheral portion in terms of particle size distribution, the reheating gas passes through and is heated only in the outer peripheral portion. The tendency will be promoted.

Therefore, when the reheating gas is blown into the upper portion of the CDQ without using a disperser or the like, the temperature of the red hot coke on the outer peripheral portion rises, but the temperature of the central portion is hard to pass through, and conversely the temperature does not rise easily. become. That is, the coke temperature becomes uneven in the radial direction inside the CDQ, and as a result, the coke quality greatly varies.

On the other hand, when the disperser is installed as in the present invention, the particle size distribution of the red hot coke in the CDQ in the radial direction can be adjusted. For example, as one preferable form, the coarse coke is preferentially present in the center. It is possible to realize such a particle size distribution. As a result, the reheating gas also passes through the coke in the central portion, eliminating the above-mentioned inconvenience and allowing uniform heating.

The disperser used in the present invention may be any one which is already well known in the technical field of powder processing, and its kind and specific shape do not impose any restrictions on the method of the present invention. For example, a conical disperser or a chute with a variable input position may be used. By using such a disperser, for example, by depositing red hot coke from the outer peripheral portion of the CDQ and forming it into a mortar shape, it becomes possible to preferentially allow the coarse coke to exist in the central portion. In other words, as long as it exerts such an action, it is not limited to a particular one.

The reheated gas for reheating gas is blown from the CDQ upper, passed through a red-hot coke immediately after turned on, reheating coke. Methods of reheating the coke include a method of using reaction heat between oxygen in the gas and red hot coke or a gas generated from the coke, and a method of blowing hot air having no oxygen or the like and having low reactivity to transfer the heat. As described above as a drawback of the known technique, in large-scale equipment using CDQ, local heating of coke and burnout are problems. Is preferable because it can heat a wider range of red hot coke more uniformly. Therefore, the present invention heats by the method. That is, the reheating gas component has a low oxygen concentration and a low reactivity with the red hot coke, and a gas having a temperature not lower than the carbonization temperature is used.

The components of the reheating gas, the heat source, and the manufacturing method are various in detail, and there is no technical problem as long as the above conditions are satisfied (for example, the total amount of the reactive gas such as N ₂ is In the present invention, it is produced by burning the circulating gas for heat exchange in the CDQ, which contains a combustible gas.

The reheating gas produced by combustion of the circulating gas of the present invention will be described in detail below. The circulating gas for heat exchange that circulates inside the CDQ is, for example, about 1500 Nm ³ per ton of coke charged, and this circulating gas generally contains a considerable amount of combustible components. The combustible components are carbon monoxide produced mainly by the carbon dioxide in the circulating gas attacking the carbon of the red hot coke at high temperature, and hydrogen produced in the process of reheating and raising the temperature of the medium temperature carbonization coke. .

In the present invention, the combustion of the combustible components in the circulating gas is used as a heat source to heat the reheating gas and the red hot coke. For example, by supplying hot air produced by burning about 150 Nm ³ of circulating gas per ton of coke to the medium-temperature carbonization coke charged to the CDQ prechamber part with an average temperature of 850 ° C as reheating gas, red heat is generated. It is possible to raise the coke temperature to around 950 ° C. As a result, the coke quality is sufficiently improved.

The reheating gas blown into the pre-chamber section joins the circulating gas under the CDQ after heating the coke,
The heat is recovered by introducing it from the flue to the boiler section. It should be noted that the method of burning the circulating gas and the burning place do not impose any restrictions on the method of the present invention, and it is possible to produce a reheating gas in advance outside the CDQ and blow it into the CDQ. It is also possible to combust the circulating gas to produce a reheating gas.

Reheating temperature The present invention utilizes the fact that the higher the temperature, the higher the strength of coke up to 950 ° C. Even if the temperature is not sufficiently raised in the coke oven, the coke quality is raised by the CDQ. (Strength, etc.) is improved. Therefore, when reheating,
The reheating temperature must be higher than the carbonization temperature. In the examples, data is shown in which no improvement in coke quality (strength) is observed when the reheating temperature is lower than the dry distillation temperature in the coke oven.

Regarding the carbonization temperature The quality of the medium temperature carbonization coke will be safely and economically improved by the method of the present invention, but as the coke to be used here, those having an average carbonization temperature of 900 ° C. or less are preferable. .

When the method of the present invention is applied to coke which has been carbonized at a temperature of 900 ° C. or higher, the quality is improved, but from the viewpoint of ensuring the quality equivalent to that of the existing blast furnace coke, it is troublesome. However, it is not economically advantageous to target such coke because the required quality improvement and improvement are small. Furthermore, in coke having a higher carbonization temperature than this, the amount of pyrolysis gas containing hydrogen as a main component at the time of reheating decreases, and thus there is a high possibility that the combustible components in the circulating gas become insufficient.

Therefore, the present invention is preferably directed to coke having an average carbonization temperature of 900 ° C. or less in order to sufficiently exert the economic effect and further maintain the stability of the process, and the carbonization temperature thereof is preferable. The lower the value, the greater the effect and the more preferable. However, if the carbonization temperature is too low, there is a problem in discharging the coke cake from the coke oven (for example, it cannot be extruded), so the carbonization temperature is 750.
C. or higher is preferable.

[0033]

EXAMPLE FIG. 2 illustrates a CDQ for carrying out the present invention. A specific description will be given using this. First, a basic operation will be described based on an embodiment of the present invention. Average carbonization temperature 85
Red hot coke 1, which is medium temperature dry distillation coke discharged from the coke oven after carbonization at 0 ° C, was charged into the prechamber part 4 of the coke dry fire extinguishing system (CDQ) 2 via the disperser 3, and the circulating gas inside the CDQ was charged into it. The high temperature combustion waste gas (reheating gas) 17 produced by burning the above in a combustion furnace 16 at a predetermined air-fuel ratio was sprayed to raise the coke temperature to 950 ° C. Then CDQ
The coke is cooled by the circulating gas in the cooling unit 5, and 175
Cold coke 6 whose temperature had dropped to ℃ was cut out from the lower part of CDQ.

On the other hand, the circulating gas for recovering the sensible heat of the coke and the reheating gas supplied to the pre-chamber are CD
It is discharged from Q and is introduced from the flue 11 through the dust remover 12 into the boiler 13 where heat is exchanged and then the cyclone 14 removes the coke dust and then again as the circulating gas 15 at the bottom of the CDQ, or part of it. It was introduced into the combustion furnace 16. CD at this time
The specifications in Q are as follows.

[0035]

[Table 1]

The cold coke 6 cut out from the lower part of the CDQ at this time was subjected to a drum strength test by the method specified in JIS K 2151 6.3 to determine DI ₁₅ ¹⁵⁰ . (Example 1) The presence or absence of reheating, the presence or absence of a disperser, and the conventional method (method of sufficiently heating in a coke oven) were compared. The results are summarized in Table 2. As is clear from this table, the drum strength of conventional coke discharged at an average carbonization temperature of 950 ° C is 85.9, while the strength of medium temperature carbonized coke discharged at 850 ° C is 81.3. It turns out that is inferior. Meanwhile, medium temperature carbonization coke
In the method of the present invention reheated to 950 ° C, the strength is
At 85.8, the improvement was almost comparable to that of high temperature carbonization coke, and the effect of the method of the present invention is clear. Further, in this case, the strength is 83.9 when the disperser is not installed, and it can be confirmed that it is meaningful to install the disperser as in the method of the present invention.

Example 2 The coke was reheated by changing the dry distillation temperature variously, and the strength of the coke after the treatment was measured. The results are shown in Table 3. As is clear from the table, even if the carbonization temperature in the coke oven is low, by blowing the gas for reheating to reheat it to 950 ° C, the quality is greatly improved, and it approaches that of high temperature carbonization coke. I know that On the other hand, the effect of reheating is small for coke having a dry distillation temperature of 900 ° C or higher, and it is not advisable to subject such coke to reheating.

(Example 3) The reheating temperature of red hot coke in CDQ was variously changed to reheat the coke, and the strength of the coke after the treatment was measured. The results are shown in Table 4. As is clear from the table, when the reheating temperature is lower than the carbonization temperature in the coke oven, no improvement in coke quality is observed, and it can be understood that the reheating temperature must be higher than the carbonization temperature.

[0039]

[Table 2]

[0040]

[Table 4]

[0041]

According to the method of the present invention, when coal is carbonized in a coke oven to produce blast furnace coke, the carbonization temperature is lowered for economic reasons such as improvement in productivity of the coke oven.
Reduced coke quality due to shortening of carbonization time,
Can be recovered with a dry fire extinguisher (CDQ). This makes it possible to lower the carbonization temperature and shorten the carbonization time even during the production of blast furnace coke, which requires high quality.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between carbonization temperature and coke quality (strength).

FIG. 2 is an explanatory diagram showing an example of a CDQ for implementing the present invention.

[Explanation of symbols]

1: Red hot coke 2: Dry fire extinguisher (CDQ) 3: Disperser 4: Prechamber 5: Cooling part 6: Cold coke outlet 11: Flue 12: Dust remover 13: Boiler 14: Cyclone 15: Circulating gas 16: Combustion furnace 17: Gas for reheating

Claims (2)

[Claims] 1. When performing dry fire extinguishing treatment on the red hot coke discharged from the coke oven, the red hot coke is charged through a disperser installed at the upper entrance of the fire extinguisher, and the red hot coke is charged into the fire extinguishing equipment. A method for producing coke for a blast furnace, which comprises blowing hot air generated by combustion of a circulating gas for heat exchange in a dry-type fire extinguishing facility containing a combustible gas into red hot coke to reheat the red hot coke to a temperature higher than carbonization temperature. 2. The average carbonization temperature of the red hot coke charged into the dry fire extinguishing equipment is 900 in the coke oven.
The method according to claim 1, which is lower than ° C.