JP2013032595A - In-furnace pulverization prevention apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vertical furnace operating method and an in-furnace pulverization prevention apparatus that can be applicable when any kind of coke is used, sufficiently suppress the pulverization of coke charged into a vertical furnace such as a blast furnace, and achieve a smooth and stable operation of the vertical furnace.SOLUTION: In one vertical furnace operating method, coke is separated into lump portions and pulverized portions by applying friction force to the surface of the coke, and the separated lump portions are charged into the vertical furnace for use. In another vertical furnace operating method, coke is separated into lump portions and pulverized portions by rotating the coke in a rotary drum, and the separated lump portions are charged into the vertical furnace for use. As an in-furnace pulverization prevention apparatus, an apparatus which is used in charging coke into the vertical furnace is used, comprising a rotary drum 1, a sieving device 2 for sieving the coke discharged from the rotary drum 1, and a charging device 11 for charging the oversize sieved out by the sieving device 2 from an upper part of the vertical furnace 16.

Description

  The present invention relates to a method for operating a vertical furnace, and more particularly to an in-furnace powdering prevention method and in-furnace powdering prevention equipment for vertical furnace charging coke used in a blast furnace or the like.

  In the blast furnace for producing hot metal, iron ore such as sintered ore and lump ore, and massive coke as a heat source and reducing material source are alternately charged from the top of the furnace, and the upper part of the furnace (shaft) Part) are deposited in layers. And the high-temperature air blown into the furnace from the tuyeres at the bottom of the furnace burns the coke accumulated in the furnace to generate high-temperature gas, and the high-temperature gas is between the iron ores and coke particles. The gap flows toward the top of the furnace, and the iron ore and coke are heated, and at the same time, the iron ore is reduced and melted. Therefore, if the gap between the particles is not properly secured, the distribution of the gas flow in the furnace becomes inappropriate for operation, the situation in the furnace becomes worse, and stable and smooth operation cannot be performed. Or, the productivity of the blast furnace decreases. That is, it is very important to ensure the air permeability of the raw material layer for blast furnace operation. When powder is mixed into the raw material charged from the top of the furnace, air permeability is hindered. Therefore, it is necessary to prevent the powder from being mixed as much as possible.

  In addition to the powder mixed into the raw material and charged into the furnace, there is also a problem of powder generated in the furnace. Coke exists in a lump until it is combusted by oxygen supplied from the tuyere at the bottom of the furnace after being charged from the top of the furnace, but lacks fragile parts due to physical contact with other raw materials. As a result, coke powder is generated. This powder becomes clogged between the raw material particles and causes deterioration of the stability and controllability of the gas flow in the furnace. For this reason, it is important to suppress pulverization while coke descends in the furnace.

  In order to prevent the occurrence of chipping of the fragile portion, many attempts have been made to keep the coke strength high. For example, even if a large amount of non-caking coal that causes coke strength to be reduced is added to the raw coal, the coke strength will not be reduced. A method of preventing strength reduction of the obtained coke by adding to caking coal and then charging and coking into a coke oven is known (see, for example, Patent Document 1). There is also a method for producing coke having a high porosity and a certain level of strength by adding a pore-forming agent and a binder during blending of raw coal and then charging and coking into a coke oven. It is known (for example, refer to Patent Document 2).

JP 2000-8047 A Japanese Patent Laid-Open No. 11-236573

  The methods described in Patent Document 1 and Patent Document 2 are techniques for improving coke strength by adding an additive to raw coal to improve the average substrate strength of the coke produced.

  However, even when the average substrate strength of coke is improved by blending such an additive, local blending variation (segregation) occurs in the raw material charged into the coke oven. Therefore, in part, coke with a weak substrate is manufactured, and when coke is charged into a blast furnace, the weak coke is pulverized in the furnace.

  Although it is conceivable to use only coal that can produce high-strength coke as the raw material for coke, such coal is expensive, and it is not practical to produce coke using only such varieties of coal. . Even if the strength of the produced coke is low, it is desirable to prevent the coke from being pulverized.

  Therefore, the object of the present invention is to solve such problems of the prior art, and can be applied to any kind of coke, and sufficiently suppresses the pulverization of vertical furnace charging coke such as a blast furnace. It is an object of the present invention to provide a vertical furnace operating method and furnace pulverization prevention equipment that enables smooth and stable vertical furnace operation.

The features of the present invention for solving such problems are as follows.
(1) In-furnace pulverization prevention equipment used when charging coke into a vertical furnace, to which a heated gas supply duct is connected, and a rotating drum having an inner diameter of 3 to 4 m, and the rotating drum A sieving device for sieving discharged coke, and a charging device for charging the top of the vertical furnace into the vertical furnace on the sieve that has been sieved by the sieving device, Heating gas for drying coke is supplied from the heating gas supply duct to the rotating drum, and the powdering prevention equipment in the furnace is characterized in that:
(2) The in-furnace powdering prevention apparatus according to (1), wherein a sieve mesh of the sieving device is 6 mm or more.
Furthermore, the above-described problems can be solved by the following means.
(1) The coke is separated into a lump part and a powdery part by applying a frictional force to the surface of the coke, and the separated lump part is charged into a vertical furnace and used. How to operate a vertical furnace.
(2) The method for operating a vertical furnace according to (1), wherein the coke is further separated into a lump part and a powdery part by applying a drop impact to the coke.
(3) Rotating coke in a rotating drum to separate the coke into a lump part and a powdery part, and charging the separated lump part into a vertical furnace for use. How to operate the mold furnace.
(4) The method for operating a vertical furnace according to any one of (1) to (3), wherein the sieve has a particle diameter of 6 mm or more is formed into a lump by sieving.
(5) The method for operating a vertical furnace according to any one of (1) to (4), wherein the coke subjected to the drying treatment is separated into a lump part and a powdery part.
(6) The method for operating a vertical furnace according to (3), wherein the coke is dried in a rotating drum.
(7) Used when charging coke into a vertical furnace, and a rotating drum, a sieving device for sieving the coke discharged from the rotating drum, and a sieve top screened by the sieving device. An in-furnace powdering prevention facility comprising a charging device for charging from the top of the vertical furnace.
(8) The coke is separated into a lump part and a powdery part by applying a frictional force to the surface of the coke, and the separated lump part is charged into a vertical furnace and used. Method for preventing in-furnace powdering of coke for vertical furnace charging.
(9) Further, the coke powder in the vertical furnace charging coke according to (8), wherein the coke is separated into a lump part and a powdery part by applying a drop impact to the coke. Prevention method.
(10) The method for preventing in-furnace pulverization of the coke for vertical furnace charging according to (8) or (9), wherein the sieve has a particle diameter of 6 mm or more to be a lump by sieving.
(11) In-furnace coke for vertical furnace charging coke according to any one of (8) to (10), wherein the coke that has been subjected to the drying treatment is separated into a lump part and a powdery part Prevention method.
(12) A method for preventing in-furnace pulverization of vertical furnace charging coke according to any one of (9) to (11), wherein frictional force and drop impact are applied to the coke in the rotating drum. .
(13) The method for preventing in-furnace powdering of coke for vertical furnace charging according to (12), wherein the coke is dried in a rotating drum.

  According to the present invention, pulverization of coke charged into a vertical furnace such as a blast furnace can be suppressed regardless of the strength of the coke used. This enables smooth and stable furnace operation, and improves the productivity of the furnace.

It is a flowchart which shows one Embodiment of the in-furnace powdering prevention method of the coke for vertical furnace charging. It is a longitudinal cross-sectional view which shows an example of the rotating drum used for this invention. It is a cross-sectional view which shows an example of the rotating drum used for this invention. Schematic which shows one Embodiment of the in-furnace powdering prevention equipment. The graph which shows the effect of drying of coke.

  Conventional handling of coke for vertical furnace charging has been made in order to minimize the impact on the coke and prevent coke pulverization. In other words, the handling that prevents the coke from being damaged due to the force applied to the coke during the process of conveying the coke to the vertical furnace has been considered good. However, when the coke has a fragile portion, pulverization occurs in the furnace no matter how small the impact applied to the coke before charging the vertical furnace. Therefore, the present inventors conversely increase the impact applied to the coke before charging the vertical furnace, thereby preliminarily pulverizing the fragile part of the surface of the coke, and removing the powdery part into the vertical furnace. By charging, it is considered that coke pulverization in the furnace can be suppressed, and the coke is rubbed together, and the coke surface is separated into cohesive parts and powdery parts by applying frictional force to the surface of the coke, The present inventors have found that powder separation in the furnace can be prevented by charging and using the separated lump in a vertical furnace and completed the present invention. In addition to the frictional force, by applying a drop impact, not only the brittle part of the coke surface but also the destruction of coke due to the cracks existing inside the coke is promoted, and a larger amount of powdery part is generated. Can be separated.

  Separation of the massive part and the powdery part is preferably performed using a sieve. The mass portion charged in the furnace preferably has a particle size of about 6 mm or more, and preferably has a screen size of 6 mm or more.

  If the water content of the coke is high, the sieving efficiency is reduced, and there is a case where the lumpy part and the powdery part are not sufficiently separated, so the coke that has been dried is separated into the lumpy part and the powdery part. It is preferable to do. It is efficient to dry the coke while applying a frictional force and a drop impact in a rotating drum described later.

  In order to apply frictional force or drop impact to coke, it is only necessary to rub the coke together, and even if it is dropped from a hopper etc., a certain effect can be obtained, but in order to promote pulverization of the fragile part, rotation It is particularly effective to stir the coke in the drum to give the coke a frictional force and a drop impact.

  Used to charge coke into a vertical furnace to apply frictional force and drop impact, and to separate and remove the powdery part. Sieve the rotating drum and the coke discharged from the rotating drum. In-furnace pulverization prevention equipment comprising: a sieving device to be charged, and a charging device for charging the top of the sieving screened by the sieving device from the upper part of the vertical furnace can be used. The rotating drum preferably has a stirring blade for lifting and dropping the coke inside the drum.

  In addition, it can be considered that the coke yield decreases and the coke cost increases by separating and removing the powdery part, but powdered coke is used in various applications as a high value-added product in steelworks and others. Therefore, the coke as a whole can be used effectively, and the cost increase does not become a problem.

  The vertical furnace used in the present invention is a blast furnace, a shaft furnace, a gasification melting furnace, or the like, and is used by charging massive coke from the top of the furnace.

  Hereinafter, an embodiment when the present invention is used in a blast furnace will be described based on the circumstances leading to the present invention.

  The red hot coke pushed out from the coke oven is lowered to a discharge place on a belt conveyor called a wharf after sprinkling fire. Then, after cutting out from the wharf, the mass is crushed with a coke cutter (a type of roll crusher) and then only the desired size is used in the blast furnace through a sieve under the hopper (storage tank) of the blast furnace. . In recent years, in view of energy saving and environmental measures, there is a case where reddish coke is cooled with gas and called “dry fire extinguishing” and then sent to the blast furnace through the same route.

  First, the present inventors consider that in such conventional coke treatment, the fragile portion of coke is not completely removed, but is charged into a blast furnace, and after applying sufficient frictional force between cokes, sieving is performed. I thought that the weak part could be removed by doing. As shown in FIG. 1, rotary drum type sizing means (hereinafter simply referred to as “rotary drum”) is further provided in the path from the coke factory or from the coke product yard to the storage tank. Therefore, the fragile part was separated and pulverized, passed through a sieve 2 and adjusted to a predetermined particle size (for example, 6 to 75 mm), and then sent to a blast furnace storage tank. At that time, a coke sample is collected between the rotating drum 1 and the sieve 2, the strength test of the coke sample is performed, and the strength data is fed back to the rotating drum 1 while adjusting the rotational speed of the rotating drum 1. The coke that satisfies the charging standards (for example, in-house standards) related to the strength and particle size was charged into the blast furnace.

  Here, as an example, the rotating drum 1 is configured as shown in FIG. That is, it is a cylindrical rotating drum 1, and coke is supplied to one end 1 a of the rotating drum 1. The coke is rotated around the cylindrical axis of the rotating drum 1, and the inner coke rolls in the circumferential direction while friction is generated. And impact the coke by dropping. The rotating drum 1 is disposed so as to be inclined downward by about 5 to 10 degrees from one end 1a for supplying coke to the other end 1b, and the coke moves to the other end 1b while rolling. On the other end side, there is a coke discharge port 3, and the entire amount of coke exiting the coke discharge port is sent by a belt conveyor 4 to a subsequent sieve 2.

  What is necessary is just to determine the dimension of the said rotating drum 1 suitably according to the quantity of the coke to process. For example, in a normal coke factory, the amount of coke processed is about 150 t / H (tons / hour) to 250 t / H. In this case, the inner diameter of the rotating drum 1 is 3 to 4 m, and the length is 25 to 30 m. The degree is appropriate. A plurality of stirring blades 5 are attached to the inner surface of the rotating drum 1 at regular intervals in the circumferential direction so as to promote destruction of the fragile portion by lifting and dropping coke. FIG. 3 shows an example in which a steel plate having a height of 50 mm is provided along the drum axis at intervals of 180 ° in the circumferential direction, and the coke is produced to some extent by the stirring blade 5 in accordance with the rotation of the cylinder. It repeats rolling to fall from where it has risen to an angle.

  When such rolling is repeated, the fragile portion in the coke structure is almost destroyed and becomes powder, and the portion remaining in a lump is almost free of the fragile portion.

  Moreover, in this embodiment, as above-mentioned, the coke discharged | emitted from the rotating drum 1 is sent to the sieve 2, and is arrange | equalized with the particle size used by a blast furnace, and before sending to the sieve 2, a part of coke is sent. The strength test is performed by sampling, and this strength test method may be a test method appropriately determined for each blast furnace. As an example, there is a drum strength defined in JIS K 2151 (Chapter 9, “Coke Test Methods”, 9.2: Drum Method). Of course, a tumbler method described in the same standard or the like, which is generally used as a test method for coke strength, may be used.

  When the result of this strength test is higher than the upper limit of the control value of the target strength in the blast furnace supplying coke, the rotational speed of the rotary drum 1 is reduced. If the lower limit of the target intensity management value is lower, the rotational speed of the rotary drum 1 is increased.

  By adjusting the degree of destruction of the weak portion of the coke in the rotating drum 1 in this way, the strength of the coke can be adjusted to a certain value or more without changing the blending of raw coal during the production of coke. And stable blast furnace operation is possible. In the present invention, if the coke strength is higher than the upper limit of the target strength even if the rotational speed of the rotary drum 1 is reduced, the blending of coal supplied to the coke oven may be changed to provide a cheaper blend. . In addition, when the rotational speed is positively increased and a strength higher than the target is obtained, the composition can be made inexpensive so that the strength decreases to the target strength.

  As mentioned above, the case where a rotating drum type facility is used as a means for forcibly removing the weak part of coke was taken as an example, but the function of removing the weak part of coke in advance by applying friction to the surface of the coke As long as the frictional force, drop impact strength, and time can be changed, any structure may be used. As in the present invention, if the fragile portion is removed in advance, the amount of powder coke below the sieve 2 that cannot be used in the blast furnace increases. Since it can be used, it will not be wasted.

  Next, separation of the coke that has been subjected to the drying process into a lump part and a powdery part will be described.

  The coke powder that is generated when a friction force is applied to the surface of the coke and when the drop impact is applied to the coke is a coke powder that is generated when the coke used contains a large amount of water. When using a sieve for separation, the powdery part cannot be sufficiently separated and removed by this sieve, or the sieve itself is clogged and the coke powdery part cannot be removed. . The powdery part that adheres to the coke lump and cannot be separated and removed by sieving is transported to the top of the vertical furnace while being attached to the coke lump, and is dried by the heat in the furnace. Since the coke lump is separated from the surface of the coke lump, a large amount of powdery coke is charged into the furnace, and the powdery part flows through the gap between the raw materials in the furnace and clogs the gap between the raw materials. When the present invention is used for coke having a high moisture content, there is a concern that it promotes pulverization rather than preventing pulverization in the furnace.

  It is known that a phenomenon in which a powdery part adheres to a coke-like part and separation thereof becomes difficult increases in proportion to the water content of the coke. Therefore, it is preferable to sieve the coke in a dry state, and it is preferable that the amount of water contained in the coke is as small as possible. For that purpose, when applying frictional force or drop impact to the surface of coke, it is arranged at the downstream side to reduce the coke-containing water content by applying constant heat to coke in advance, at the same time or after application. Therefore, it is preferable to dry the coke before sieving.

  The heating method for drying the coke is preferably performed by introducing a heating gas into a container containing coke, and various heating gases generated in a factory are preferably used. In order to remove moisture contained in coke, it is desirable to use hot-blast furnace combustion exhaust gas or heating furnace exhaust gas with low oxygen concentration. Can also be generated. In addition, as long as nitrogen for controlling the oxygen concentration is introduced, a heated gas such as a cooler exhaust heat of a sintering machine can be used.

  The temperature of the heated gas is sufficient if the coke can be dried, and 60 ° C. or higher is sufficient for drying the coke, and it is desirable to set it to 200 ° C. or lower. This is because moisture contained in coke, which is a carbonaceous material, is dried, so that it is difficult to prevent fire and explosion if the temperature of the heated gas is too high.

  FIG. 4 shows a rotating drum and a sieving device for sieving the coke discharged from the rotating drum, used when charging the coke into the vertical furnace when drying the coke in the rotating drum. 1 shows an embodiment of the in-furnace powdering prevention equipment comprising a charging device for charging the top of the sieve screened by the screening device from the upper part of the vertical furnace. In FIG. 4, the coke supplied into the rotary drum 1 via the supply conveyor 6 and the screw feeder 7 is stirred while being dried by the heated gas 9 sent from the heated gas supply duct 8 into the rotary drum 1, The fragile part is powdered by friction and drop impact. The coke discharged from the coke discharge port 3 is conveyed to the sieve 2 by the discharge conveyor 4 and separated into a lump part and a powdery part by sieving. The lump portion on the sieve is conveyed by the vertical furnace conveyer 10 and is charged from above the vertical furnace 16 by the charging device 11. The powdery part under the sieve is conveyed by the powder extraction conveyor 12 and used separately. 13 is a dust collecting bag filter, 14 is a dust collecting fan, and 15 is an exhaust gas chimney.

Using the same equipment as shown in FIGS. 1, 2, and 3, a test for coke treatment at 190 to 250 t / H and transporting to a blast furnace was performed. As the rotating drum 1, one having an inner diameter of 3.5 m and an effective drum length from the charging end to the discharging end of coke: 27.7 m was used. Further, a belt conveyor that bypasses the rotating drum 1 was provided, sampling was performed on the upstream side of the sieve 2 at regular time intervals, and a test of a comparative example in which only the coke strength was measured was also performed. Strength of the coke was measured at prescribed in JIS K 2151 "drum strength", the particle size of the coke sample when strength measurement 15 mm, as 150rpm rotational speed of the test drum, the so-called "drum intensity (symbol DI ^0.99 ₁₅ ) ”. The sieve mesh of the sieve 2 was 6 mm.

  In the case of the comparative example in which the treatment with the rotating drum 1 is not performed, the coke strength sampled on the upstream side of the sieve 2 is 84.3 on average, but the rotating drum 1 causes the coke to rotate at 5 rpm for 20 minutes. When processed, the coke drum strength increased to 85.1. That is, the strength of the coke charged into the blast furnace could be increased by 0.8 points by removing the weak portion of the coke by the treatment with the rotating drum.

  Compared to the normal operation of charging the sieve top of the sieve 2 into the blast furnace without performing the treatment with the rotating drum, the operation test of the present invention in which the sieve top of the sieve 2 is charged into the blast furnace after the treatment with the rotating drum. In this case, coke pulverization in the blast furnace was suppressed, so the air permeability of the blast furnace was improved, the gas flow distribution in the furnace was maintained properly, the furnace condition was stabilized, and smooth operation As a result, the amount of molten iron was improved by 5% under the same operating conditions.

  When using the same equipment as shown in FIG. 4 and applying a frictional force and a drop impact to the surface of the coke by the rotating drum, at the same time, constant heat is applied to the coke by a heating gas (combustion exhaust gas) of 150 ° C. In addition, the case where drying was performed with a reduced amount of coke-containing water and the case where drying was not performed were each processed and sieved. The separation of the coke and powdery coke after sieving was compared between the case where the moisture content of the coke on the rotating drum outlet side was 2 mass% or less and the case where the moisture content was high without applying heat. The results are shown in FIG. The vertical axis in FIG. 5 is the ratio of the powdery part having a particle size of 6 mm or less, which is the fraction under the sieve, mixed on the sieve when sieving with a sieve of 6 mm. When the black circle is dried, This is the case when it did not dry.

  In FIG. 5, for example, when the coke with a moisture content of more than 4 mass% when not dried is reduced to a moisture content of 0 mass% by drying, the separation situation differs greatly, and when a sieve with a mesh size of 6 mm is used, The mixing rate of coke (-6 mm) with a particle size of 6 mm or less was reduced from the 3 mass% range to about 0.5 mass%. The reduction in the water content of coke greatly affected the separation of the powdery portion of coke, and it was found that the drying treatment is very effective in preventing in-furnace powdering for coke having a high water content.

DESCRIPTION OF SYMBOLS 1 Rotating drum 1a, 1b End part 2 Sieve 3 Coke discharge port 4 Belt conveyor 5 Stirring blade 6 Supply conveyor 7 Screw feeder 8 Heating gas supply duct 9 Heating gas 10 Conveyor for vertical furnace 11 Loading device 12 Powder extraction conveyor 13 Dust collection bug filter 14 Dust collection fan 15 Exhaust gas chimney 16 Vertical furnace

Claims (2)

In-furnace powdering prevention equipment used when charging coke into a vertical furnace,
A rotating drum having an inner diameter of 3 to 4 m, to which a heated gas supply duct is connected;
A sieving device for sieving the coke discharged from the rotating drum;
A charging device for charging the top of the vertical furnace into the vertical furnace from the upper part of the vertical furnace;
In-furnace powdering prevention equipment, wherein heated gas for drying the coke is supplied to the rotating drum from the heated gas supply duct.   The in-furnace pulverization prevention facility according to claim 1, wherein a sieve mesh of the sieving device is 6 mm or more.

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