JP5320833B2 - Vertical furnace operation method and vertical furnace charging coke in-furnace prevention equipment - Google Patents

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 a vertical furnace charging coke in-furnace prevention equipment that enables smooth and stable vertical furnace operation.

The features of the present invention for solving such problems are as follows.
(1) Using a plurality of sieving devices arranged with steps, the coke is dropped from a sieving device having a sieving mesh at a higher position to a sieving device having a sieving mesh at a lower position. A method for operating a vertical furnace, wherein the coke is separated into a lump part and a powdery part, and the lump part collected as a sieve is inserted into a vertical furnace and used.
(2) The method for operating a vertical furnace as described in (1), wherein a sieve having a particle diameter of 6 mm or more is charged into a vertical furnace for use.
(3) The method for operating a vertical furnace according to (1) or (2), wherein the coke subjected to the drying treatment is separated into a lump part and a powdery part.
(4) A coke supply device that is used when charging coke into a vertical furnace and supplies coke to a sieving device, a plurality of sieving devices arranged with steps, and sieving with the sieving device An apparatus for preventing in-furnace pulverization of coke for vertical furnace charging, comprising a charging device for charging the divided sieves from above the vertical furnace.
(5) The sieving device has an expandable and contractible sieving mesh and a vibration mechanism for deforming the sieving mesh, and prevents in-furnace coking of the vertical furnace charging coke according to (4) Facility.

  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.

  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, By using the separated lump part in a vertical furnace, it is possible to prevent in-furnace pulverization, and in addition to frictional force, drop impact is applied to not only the weak part of the coke surface, but also inside the coke. We found that it is possible to promote the destruction of coke due to the cause of existing cracks, generate a larger amount of powdery parts and separate them, and for this purpose, a plurality of sieving devices arranged with steps are arranged. Used, with a sieving net at a higher position The present invention was completed by finding that it is effective to separate the coke from the sieving device to the sieving device having a sieving net at a lower position while dropping the coke into a lump part and a powdery part. . Furthermore, it has been found that a larger amount of powdery portions can be generated and separated by applying an impact caused by vibration of a sieve screen.

  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.

  In order to impart frictional force and impact to the coke, the coke may be rubbed together, and a certain effect can be obtained just by dropping from the hopper or the like, but in order to promote powdering of the fragile part, Applying frictional force and drop impact to coke by using a plurality of sieving devices arranged with such steps and moving through a continuous sieving mesh, and further impact caused by vibration of the sieving mesh Is particularly effective.

  A coke supply device that is used when charging coke into a vertical furnace to apply frictional force or impact to the coke and separate and remove the powdery part. A plurality of sieving devices arranged side by side and a charging device for charging the top of the sieving sieve screened by the sieving device from the upper part of the vertical furnace. In-furnace powdering prevention equipment can be used. The sieving screen of the sieving device preferably has a structure in which the screen can be changed easily. Further, it is preferable that the step between the sieving screens of each sieving device can be changed.

  Furthermore, it is preferable that the sieving device has an expandable / contractible sieving net and a movable mechanism for deforming the sieving net. As such a sieving device, for example, a special screen having a vibrating screen that can expand and contract, and a vibrating mechanism that conveys the raw material while deforming it in conjunction with the upper, lower, left and right, such as a jumping screen (registered trademark), is used. Can do. With Jumping Screen (registered trademark), it is possible to expect the effect that the raw material is bounced up by giving repeated movements of pulling and loosening to the urethane mesh, and impact is given when falling. Further, since the mesh is always deformed, clogging is unlikely to occur even when a wet raw material is used.

  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, a coke bed type 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 the blast furnace, and sifting while applying sufficient frictional force and impact to each other. We thought that fragile parts could be removed by dividing. Then, as shown in FIG. 1, in the path from the coke plant or from the coke product yard to the storage tank, the screens are arranged so that the height of the sieve mesh decreases from the upstream side to the downstream side of the coke transport line. And a continuous sieving device 1 (in FIG. 1, sieving devices 1a, 1b, 1c) are dropped from the sieving device 1a to the sieving device 1b and from the sieving device 1b to the sieving device 1c, By sieving while applying sufficient frictional force and impact to the slag, it was adjusted to a predetermined particle size (for example, 30 to 75 mm) and then sent to a blast furnace storage tank. At that time, a coke sample is collected after passing through the sieve mesh 2c, the strength test of the coke sample is performed, and the frequency data of the vibration mechanism that deforms each sieve mesh 2 is feedback-controlled using the strength data, and the sieve mesh frequency is obtained. While adjusting the mesh, adjust the mesh between the sieve mesh 2 and the level difference between the sieve meshes 2 to obtain coke that satisfies the charging standards (for example, in-house standards) regarding strength and particle size, via the storage tank The blast furnace 7 was charged.

  Here, as an example of the sieving device, one having a configuration as shown in FIG. 1 is used. That is, the sieving meshes 2 are continuously arranged at different heights, and the sieving powder storage hopper 3 is installed below the sieving meshes 2. Coke is supplied to the uppermost sieve mesh 2a on the upstream side, the sieve mesh 2a is vibrated, further dropped continuously to the sieve mesh 2b and the sieve mesh 2c, and vibrated in each sieve mesh, Impacts due to friction and dropping, and impacts due to sieve screen vibration are applied to the coke. The sieve mesh 2 is disposed so as to be inclined downward by about 15 to 30 ° from one end for supplying coke to the other end for discharging the coke, and the coke is a frictional force generated between the impact of the sieve mesh vibration and the coke. It moves on the sieve net 2 while receiving. If the next sieve mesh 2b is installed on the other end side of the sieve mesh 2a, the coke moves to the next sieve mesh 2b while receiving a drop impact. Further, the coke discharged from the sieving net 2b passes through the next sieving net 2c, and the entire amount of the coke is sent to the subsequent process by the belt conveyor 5. 4 is a coke supply belt conveyor, and 6 is a belt conveyor for extracting powdery parts.

  In the above embodiment, the case where there are three sieving devices has been shown, but an appropriate number of two or more can be installed according to the equipment situation. The larger the step distance between the sieving devices, the more effective, but the step distance that can be set in the equipment situation is limited. For example, in a normal coke factory, the amount of coke processed is about 150 t / H (tons / hour) to 250 t / H. In the above case where the continuous sieving apparatus is used as three stages, the size of one sieving mesh is 3 About 10 m is appropriate.

  When the vibration as described above is repeated with the continuous sieving device, 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 continuous sieving apparatus is arrange | equalized with the particle size used with a blast furnace. A strength test is performed by sampling a part of the coke on the exit side of the sieving net 2c. This strength test method may be a test method appropriately determined individually 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 frequency of the sieve mesh 2 is reduced. If the result of the strength test is higher than the upper limit of the target control value even if the vibration frequency of the sieving mesh 2 is lowered, the mesh size of the sieving mesh 2 is increased within the specified value range, or The level difference is adjusted so as to reduce the maximum level difference between the level difference or the sieve mesh 2 and the belt conveyors 4 and 5. Moreover, when it is lower than the lower limit of the management value of the target strength, the frequency of the sieving net 2 is increased. Further, if the strength test result is higher than the lower limit of the target control value even if the frequency of the sieve mesh 2 is increased, the mesh size of the sieve mesh 2 is reduced within a specified value range, or the sieve mesh 2 The level difference is adjusted so as to increase the maximum level of the level difference between the steps or the sieve net 2 and the belt conveyors 4 and 5.

  By adjusting the degree of destruction of the coke fragile portion in the continuous sieving equipment in this way, the coke strength can be adjusted to a certain value or more smoothly without changing the composition of raw coal during the production of coke. In addition, stable blast furnace operation is possible. In the present invention, when the strength of the obtained coke is higher than the upper limit of the target strength, the frequency of the sieve mesh is decreased, the mesh size of the sieve mesh is increased within a specified value range, In addition to adjusting the step so as to lower the maximum value of the step between the meshes or the sieve mesh and the belt conveyor, the blending of coal supplied to the coke oven may be changed to make the blending cheaper. Also, actively increase the frequency of the sieve mesh, or increase the mesh size of the sieve mesh within the specified value range, and reduce the maximum level difference between the sieve meshes or between the sieve mesh and the belt conveyor. If a strength higher than the target is obtained even if the step is adjusted, the composition can be made inexpensive so that the strength decreases to the target strength.

  As described above, it is very effective to use a continuous sieving device as a means for forcibly removing a weak portion of coke. As in the present invention, if the fragile part is removed in advance, the amount of powder coke under sieving that cannot be used in a blast furnace increases, but generally in steel mills, powder coke is effectively used as a fuel for sintering raw materials, etc. Since it can be used, it is not 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.

  When the frictional force is applied to the surface of the coke or when the impact is applied to the coke, the coke powder is generated when the coke used contains a large amount of water. When a sieve is used 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 water content, such as inhibiting the stable gas flow, there is a concern that the effects of the present invention cannot be sufficiently exhibited.

  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 this purpose, when passing through a continuous sieve that imparts frictional force or impact to the surface of the coke, it is possible to reduce the amount of coke-containing water by adding a certain amount of heat to the coke in advance. Therefore, it is preferable to dry the coke before carrying out sieving.

  In FIG. 2, 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) having a particle size of 6 mm or less is 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.

Using a facility similar to that shown in FIG. 1, a test was conducted in which a coke treatment of 190 to 250 t / H was performed and conveyed to a blast furnace. Each sieve mesh 2 had a length of 5.0 m, and the entire three sieve meshes had an effective sieve length from the charging end to the discharge end of coke: 15.0 m. The level difference of each sieve mesh was 1.0 m. Sampling was performed on the belt conveyor 5 at regular intervals, and the coke strength was measured. In addition, a belt conveyor that bypasses the continuous sieving device 1 and conveys coke to the belt conveyor 5 is provided separately, and even when not passing through the continuous sieving device, sampling is performed on the belt conveyor 5 to measure the coke strength. It was set as a comparative example. 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 2 has a mesh size of 6 mm.

  When coke was processed by the continuous sieving device, the drum strength of the coke increased by 0.5 as compared to the comparative example in which the processing by the continuous sieving device was not performed. That is, the strength of the coke charged into the blast furnace can be increased by 0.5 points by removing the weak portion of the coke by the processing of the continuous sieving device.

  In the case of the operation test using the present invention in which the coke after the treatment by the continuous sieving apparatus is charged into the blast furnace, compared with the normal operation in which the coke not subjected to the treatment by the continuous sieving apparatus is charged into the blast furnace. Because coke pulverization in the furnace of the blast furnace was suppressed, the air permeability of the blast furnace was improved, the gas flow distribution in the furnace was maintained properly, the furnace condition was stabilized, smooth operation was possible, The amount of brewing increased by 3% under the same operating conditions.

Schematic which shows one Embodiment of the in-furnace powdering prevention equipment. The graph which shows the effect of drying of coke.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Continuous sieving apparatus 1a, 1b, 1c Sieving apparatus 2 Sieve net 2a, 2b, 2c Sieve net 3 Under-sieve powder storage hopper 3a, 3b, 3c Under-sieve powder storage hopper 4 Coke supply belt conveyor 5 Belt conveyor 6 Powdery Part extraction belt conveyor 7 Blast furnace

Claims (4)

Using a plurality of sieving devices arranged with steps, the sieving device of each sieving device is vibrated, and the sieving device having a sieving mesh at a lower position is changed from a sieving device having a sieving mesh at a higher position. The coke is separated into a lump part and a powdery part while dropping the coke, and the operation method of the vertical furnace using the lump part in a vertical furnace,
Conduct a strength test of the coke sample that becomes part of the lump collected on the sieve ,
When the strength data of the coke sample is higher than the upper limit of the control value of the target strength, the frequency of the sieve mesh is decreased, and when the strength data is lower than the lower limit of the control value of the target strength, the frequency of the sieve mesh Raise
A method of operating a vertical furnace, comprising using a sieve having a particle size of 6 mm or more in a vertical furnace. The method for operating a vertical furnace according to claim 1, wherein the coke subjected to the drying treatment is separated into a lump portion and a powdery portion. It is the equipment used for the operating method of the vertical furnace of Claim 1 or Claim 2, Comprising:
A plurality of sieving devices arranged with steps,
And coke feed device for supplying to said sieving apparatus coke,
Furnace powdering prevention equipment of the vertical RoSo needful coke, characterized in that it comprises a charging device for charging the top of the shaft furnace upper sieve that sieved by the sieving device. The equipment for preventing in-furnace pulverization of coke for vertical furnace charging according to claim 3 , wherein the sieving device has a stretchable sieving mesh and a vibration mechanism for deforming the sieving mesh.

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