JPH0733511B2 - Blast furnace coke manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing blast furnace coke. More specifically, in a room-type coke oven, carbonization is carried out at a high flue temperature, and the coke temperature in the center of the carbonization chamber is 700 to 900 ° C, which is significantly lower than in the past, and early kiln removal is performed. The present invention relates to a method for producing a blast furnace coke, which comprises heating and firing the existing coke in a prechamber of a dry fire extinguishing facility (hereinafter referred to as CDQ) to complete the blast furnace coke.

[Conventional technology]

Blast furnace coke is manufactured by dry distillation of coal in a room coke oven. The coking chamber of this coke oven has a height of 4 to 7
It is a rectangular parallelepiped with a length of m, a length of 12 to 18 m, and a width of 0.4 to 0.55 m, and is structured so that it is indirectly heated by bulging brick walls of about 100 mm thickness from the flues on both sides of the carbonization chamber. The coal is gradually carbonized from the carbonization chamber wall side toward the center. This dry-distilled coke is extruded from the carbonization chamber after the coke temperature in the center of the carbonization chamber reaches 1000 ° C or higher in order to secure the strength for conventional blast furnaces and stabilize the discharge of coke cake from the carbonization chamber. It was The flue temperature is usually maintained at 1000 ° C or higher, and the time required for carbonization from the charging of coal to the formation of coke and extrusion is 16-
It takes 29 hours, and the time required for carbonization is mainly determined by the width of the carbonization chamber and the flue temperature. At the end of the dry distillation, the temperature difference between the coke and the flue in the carbonization chamber becomes smaller, and the heat transfer rate from the flue to the coke becomes slower, so the heating time per unit temperature is extended and equipment productivity and thermal efficiency are increased. Becomes worse.

If the coke is pushed out of the carbonization chamber when the coke temperature in the center of the carbonization chamber is still low, the dry distillation time at the end of dry distillation, which is inefficient, can be shortened, but the coke discharged from the kiln at low temperature is not yet strong enough. No examples have been implemented because of increased powdering in the transportation process and in the blast furnace. This is mainly because there was no heating / firing means that could improve the quality of coke after kiln removal. As a conventionally known document, iron and steel Vol 73 (1987) 12, S791 has a physicochemical property in the carbonization process of coal that has an inflection point near 800 ° C and is heated to 800 ° C or higher. For the first time, it is disclosed that the degree of graphitization Lc, which is a controlling factor of hot properties, starts to increase. Also, in Materials and Process Vol 1 (1988), 1004,
When the carbonization temperature near the center of the carbonization chamber is 670 ℃ to 1100 ℃ and the carbonization is completed and cooled, the lower the final carbonization temperature, the worse the physicochemical properties of the coke, and the larger the difference in the properties inside the coke mass. However, by reheating up to 1100 ° C under N ₂ gas atmosphere, all coke recovered to almost the same physicochemical properties as coke carbonized to the final temperature of 1100 ° C, and the properties inside the coke mass were also homogenized. Has been shown to do. These publicly known documents are those in which the temperature of the center of the coking chamber was 670 to 1100 ° C and the dry distillation was completed, and when it was considered that the coke was charged into the blast furnace (blast furnace), it was post-heated in the shaft portion of the blast furnace, With the hopeful goal that the coke properties will eventually be recovered and homogenized by the time it reaches the lower part of the blast furnace, which requires strength (actually, difficulty in low-temperature coke kiln removal, coke deterioration due to cooling, However, it is not realized due to the difficulty of handling the blast furnace and the opposition of the blast furnace engineer, etc.), but the purpose is to fundamentally examine the changes in the coke properties during the carbonization process. It is carried out in an N ₂ gas atmosphere, assuming that the above, and there is no description about the carbonization method for lowering the coke oven temperature. In addition, since the strength of coke having a low carbonization temperature is not yet sufficiently developed, minute cracks are generated by thermal stress during cooling, which adversely affects strength recovery due to reheating. Heating is not preferred.

Further, JP-A-61-103987 discloses that coal of 100-400
Preheat by air flow drying to ℃, then put in an indirect heating vertical continuous carbonization furnace and dry-distill to 800-900 ℃, then 1000-1200
A continuous production method of blast furnace coke in which direct heating and calcination is performed with a heating gas to 0 ° C is disclosed. This method is intended to avoid the use of current room coke ovens,
It cannot be a practical method because a continuous dry distillation maintenance, which is considered to be difficult to continuously descend due to thermal expansion between 400 and 500 ° C, must be newly developed.

Extinguishing of coke extruded from a room type coke oven at a temperature of 1000 ° C or higher replaces the conventional wet extinguishing method with sprinkling water, and in recent years, the sensible heat of red hot coke is recovered as steam.
For use, the dry fire extinguishing method using coke dry fire extinguishing equipment (CDQ) is widely used. Since this CDQ is aimed at extinguishing coke and recovering steam, it is disclosed that air is blown into the CDQ to burn a part of the coke in order to increase the recovery amount of steam and reduce fluctuation. (Example: JP-A-61-37893). In this publication, there is also an expression of flammable gas in the sense that there is no generated gas, but originally, since it is coke that has completed coking in a coke oven and is burnt out from the kiln, flammable gas is insignificant. Most of the generated heat is generated by burning a part of the coke. The partial combustion of this coke is intended to reduce the increase and fluctuation of the amount of vapor recovery.
No heating and firing for the purpose of improving the properties of coke have been carried out, and no such proposal has been found.

[Problems to be Solved by the Invention]

Conventionally, the coke in the carbonization chamber immediately before being taken out from the kiln is fired at a center temperature of 1000 ° C or higher. Therefore, at a flue temperature of 1000 ° C to 1300 ° C, the carbonization time required for coke production reaches 16 hours to 29 hours, and a huge amount of carbonization heat of 550 to 650 Kcal per kg of coal is required. And it is no exaggeration to say that the amount of heat from dry distillation occupies most of the coke production price.

Furthermore, the coke industry is an equipment industry, and the coke oven 1
A huge capital investment of about 200 million yen is required to construct one gate, and about 20 billion yen to construct one reactor group with 100 gates. For example, reducing the carbonization time in a coke oven by 15% means that the number of coking chambers can be reduced by 15% to produce the same amount of coke. Therefore, shortening the dry distillation time is an important technical issue for suppressing capital investment.

An object of the present invention is to provide a coke production technique that combines a room-type coke oven generally used in the production of blast furnace coke and a CDQ facility to improve the efficiency of the carbonization process, and obtain a low carbonization heat amount and high productivity. It is to be.

[Means for Solving the Problems]

If the coke has a strength that can withstand handling during the process from the kiln removal in the coke oven to the blast furnace charging, the coke is removed at the lowest possible temperature and reheated in the upper part of the blast furnace to make the physical properties of the coke. There is also an idea that the recovery of chemical properties should be measured. However, the coke as it is kiln-fired at low temperature has a large difference in properties within the coke mass, and the CSR index of hot properties (strength after CO ₂ reaction at high temperature)
However, it is extremely difficult to get this coke to be used in a blast furnace, and there is no case in which it is implemented.

Therefore, the inventors of the present invention significantly reduce the amount of dry distillation heat in the coke oven by early low temperature kiln removal and increase the equipment productivity by shortening the dry distillation time, and the deteriorated coke property has sensible heat after kiln removal. Coke with almost the same quality (DI, CSR, etc.) as the existing coke, which is recovered in advance by heating and firing it in the CDQ prechamber, that is, the coke that has been completely carbonized in the coke oven. The present invention has been completed as a result of earnest research on a manufacturing method for supplying slag to a blast furnace.

That is, the present invention reduces the flue temperature of a room coke oven to 11
The temperature is set in the range of 50 ℃ to 1350 ℃, and when the coke temperature in the center of the carbonization chamber reaches the range of 700 ℃ to 900 ℃, the coke is kiln-fired, and then the coke is placed in the pre-chamber of the dry fire extinguishing equipment. At least by charging and immediately after that, introducing air into the prechamber and burning gas generated mainly from coke in the prechamber.
A method for producing blast furnace coke, which comprises heating the coke to a temperature of 900 ° C. or higher and firing it.

The point of the present invention is to set the carbonization conditions of a coke oven capable of early kiln removal at a low temperature, in particular to set the flue temperature and the kiln discharge temperature, and the gas generated from the coke mainly in the coke chamber of the CDQ. It is to find the conditions for heating the coke to the coke having the same quality as the coke which has been subjected to the high temperature carbonization in the coke oven as in the conventional method.

First, as a result of examining the relationship between the flue temperature and the kiln discharge temperature, the coke quality deteriorates as the kiln discharge temperature decreases, but the degree of deterioration of the coke quality decreases as the flue temperature increases, and the flue temperature 1150 ° C to 1350 ° C. It was found that the conditions of the present invention can be sufficiently satisfied if the kiln discharge temperature (the coke temperature at the center of the carbonization chamber) is in the range of 700 ° C to 900 ° C.

If the flue temperature is less than 1150 ° C, the rate of temperature rise in the softening and melting temperature range of coal becomes slow and the quality of the coke matrix carbon deteriorates. Therefore, the drum strength (DI) is maintained even when heating and firing in the CDQ prechamber. However, the quality of coke such as strength after hot reaction (CSR) is not improved, which is not preferable (see Comparative Example). The higher flue temperature is not a problem in the present invention, but 1350 ° C is close to the upper limit of conventional coke oven equipment.

Next, the workability at the time of extrusion and in the CDQ prechamber and the improvement of coke quality were examined in relation to the kiln discharge temperature. As a result, 7
It was found that the amount of smoke emitted was about one-third of that at temperatures below 00 ° C, and there was almost no problem with heating (combustion) and cooling work in the dry fire extinguisher box. That is, if the temperature in the center of the carbonization chamber is less than 700 ° C, there is a large amount of smoke when the kiln is discharged, and the coke volatile content is reduced.
The true specific gravity is not sufficiently increased, and the pulverization due to the kiln removal and the subsequent handling is also increased, which is not preferable. The temperature in the center of the carbonization chamber can be obtained by direct measurement, but as a predicting method, the elapsed time of carbonization until the peak of the coke oven gas temperature measured in the riser and the core temperature of the coal column are specified. Knowing the relationship of the time required to reach the temperature in advance, installing a thermocouple on the riser pipe and measuring the change over time in the gas temperature, predict the core temperature of the coal column and determine the kiln discharge timing. You can also do it.

Furthermore, the temperature of the coke mass at the center of the coal pillar was 800 ° C, and the temperature difference in the coke mass at the time of the kiln discharge was between the wall side (head) and the center (tail).
Although the temperature was 200 ° C, the amount of gas generated from the tail was large, and the temperature of the tail rose sharply compared to the head due to combustion for about 30 minutes with air, and the coke temperature of the tail was 900 ° C or higher, and The temperature difference between the tails was also reduced to about 50 ℃, and the property difference in the lump coke was also equalized to that of conventional coke.

Based on the above results, the inventors of the present invention, high temperature carbonization in a coke oven, the coke that was early low temperature kiln, charged into the CDQ pre-chamber in the red hot state as it is without cooling,
The inventors have invented a method for producing blast furnace coke, which has quality comparable to that of the conventional method by continuously heating and firing.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples.
The method of the invention is in no way limited by this example.

Table 1 shows examples of the present invention, comparative examples and conventional examples. In carrying out the method of the present invention, dry distillation was performed using a 1 / 4t test coke oven, and CDQ treatment was performed by heating and cooling coke by blowing air and N ₂ gas into a steel box. In the coke oven, the temperature at the center of the carbonization chamber is measured,
As soon as the target temperature was reached, it was removed from the kiln and placed in a steel box. Immediately after the coke is charged into the steel box, air is introduced, and the gas generated from the coke is about 1
Burned for hours. The increase in coke temperature due to combustion differed slightly depending on the flue temperature and the temperature at which the kiln was discharged, but when the temperature at which the kiln was discharged was 800 ° C, it rose to over 900 ° C in 30 minutes. Then, simultaneously with the end of combustion, N ₂ gas was introduced and cooled. Table 1 shows the coke quality after cooling.

In the conventional example Compared to CSR = 55.5 to 57.5, in the method of the present invention, It was found that a quality level comparable to CSR = 57.0-57.5 can be obtained.

On the other hand, as comparative examples, one with a low flue temperature and a kiln starting temperature (Experiment No. 5), an example in which one with a high flue temperature and a kiln starting temperature was burnt with air and then cooled (Experiment No. 6) The firing temperature is low, but the firing temperature is low and combustion heating is performed with air, but the heating temperature is less than 900 ° C (Experiment No. 7) and the flue temperature is high, but the firing temperature is low and combustion heating by air introduction is Although there is no example (Experiment No. 8), Coke qualities such as CSR were considerably inferior in Experiment No. 5 and no difference in Experiment No. 6 as compared with the method of the present invention and the conventional method. In Experiment No. 7 and Experiment No. 8 And the deterioration of CSR was clearly recognized. As a result, in the case of low temperature kiln removal, the coke quality does not recover even if the flue temperature is low even if reheated, and the quality improvement effect is obtained even if the coke fired to a high temperature is heated by combustion with air. Turned out not to be. In addition, when the flue temperature is high, the low temperature kiln is discharged and there is no combustion heating due to air introduction, and the heating temperature is less than 900 ° C And the deterioration of CSR was clearly recognized.

It was feared that the coke dust rate (−15mm) would increase by firing the coke from the coke oven in the state where the temperature of the coke in the center was only fired at 800 to 900 ° C. Immediately after, a drop impact of about 6 m was applied to the red hot coke and the powder ratio was measured.
~ 7.5 (%), while the method of the present invention is 6.2-7.5.
It was almost the same as (%). On the other hand, the flue temperature of the comparison method and the firing temperature are 10.5
It became as high as (%). In addition, although the flue temperature and the kiln discharge temperature of the comparative method are not different from those of the method of the present invention and the conventional method, this is the result of coke immediately after the kiln discharge,
When air is burned and heated in the CDQ, it is considered that the coke burns because the amount of gas generated from the coke is small and the powder rate slightly increases. The powder ratio did not increase in the method of the present invention, the destruction by drop impact is mainly volume fracture starting from cracks and thermal strain in the coke lump, and in the method of the present invention, because of low temperature kiln, high temperature kiln It is presumed that the generation and growth of cracks in the coke lump due to the compaction during the high-temperature firing process were less than that of the out-coke. This allows
It was judged that there was no concern about pulverization during the CDQ charging process from the low temperature kiln discharge coke kiln removal.

From the above, in the present invention, appropriate carbonization conditions (furnace temperature) and kiln discharge temperature in the coke oven are set,
It was found that the proper heating and firing by introducing air into the CDQ pre-chamber is an important technical point.

[Action]

Conventionally, the introduction of air to reheat the coke that has been discharged from an early low-temperature kiln (although it has been difficult to discharge the low-temperature kiln itself) is inevitable as a result of burning a part of the coke. However, it was not implemented because it was considered that the quality of the coke deteriorated, such as the strength of the coke decreased and the ash increased. However, when the coke lump tail contains a large amount of combustible gas, low-temperature kiln is heated by introducing air into the upper space of the CDQ pre-chamber, the combustible gas burns preferentially and the It was found that the temperature of the coke was raised in a short time within the pre-chamber residence time without disturbing the cooling process, the coke itself was hardly burned, and the quality equivalent to that of the coke which was normally carbonized in the chamber furnace was obtained.

〔The invention's effect〕

The present invention pursues the functions of a room-type coke oven and a CDQ facility that are usually used in the production of blast furnace coke, and
By investigating the coke formation process in detail,
Combining two facilities, we have created a completely new method of carbonization for coke, which has never been seen before. That is, in the conventional method, the high temperature carbonization of the coke is carried out only in the room type coke oven, whereas the present invention minimizes the carbonization in the inefficient room type coke oven by indirect heating,
High-temperature carbonization required for coke quality is an efficient method for producing coke for a blast furnace, where it is directly heated in the CDQ prechamber. This significantly reduced the amount of dry distillation heat (heat consumption reduced by about 80 Kcal / kg), and increased productivity by shortening the dry distillation time (reduced by about 15% in dry distillation time) (that is, to produce the same amount of coke) The coke oven with 85% of the number of carbonization chambers in
Was achieved. The low-temperature kiln provided coke of the same quality as the regular dry-distilled coke that had been completely dry-distilled until the end, even though the coke was extruded during the dry-distillation, and at the same time, the cost of producing coke was significantly reduced. The reduction of heat consumption is due to the reduction of CO ₂ and C
By controlling the emission of O _X and NO _X , it will make a great contribution to global environmental problems. Furthermore, since the present invention is based on effectively utilizing the existing room-type coke oven and CDQ equipment, it is extremely practical and has great social significance, such as curtailment of investment in replacement of the coke oven. To have.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-61-103987 (JP, A) JP-A-61-37893 (JP, A) JP-A-52-85203 (JP, A) JP-B 57- 15788 (JP, B2) Materials and Processes, 1 [4] (1988), 1004

Claims (1)

[Claims] 1. The flue temperature of the chamber type coke oven is set in the range of 1150 ° C to 1350 ° C, and when the coke temperature in the center of the coking chamber reaches the range of 700 ° C to 900 ° C, the coke is kiln-fired. Then, the coke is charged into a pre-chamber of a dry fire extinguishing facility, air is introduced into the pre-chamber immediately after that, and gas generated mainly from the coke is burned in the pre-chamber so that at least 900 ° C.
A method for producing coke for a blast furnace, which comprises heating the coke to the above temperature and firing it.