JP2010047798A - Coke-charging tank and method for operating vertical furnace using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for operating a vertical furnace, which can stably operate a vertical furnace by reducing an amount of the powdered coke that has been charged into a vertical furnace such as a blast furnace and has been powdered in the furnace, without increasing the cost due to a change of the raw coal for the coke and needing a complicated pretreatment for a product coke, and to provide a coke-charging tank to be used in the method for operating the vertical furnace. <P>SOLUTION: The vertical coke-charging tank 4 to be installed in a line for transporting the coke from the coke furnace 1 to the vertical furnace 6 includes: mechanisms for charging the coke from the upper part of the coke-charging tank 4 and discharging the coke from the lower part; and a stirring device for stirring the coke in the coke-charging tank 4 and imparting a friction force onto the surface of the coke. The method for operating the vertical furnace includes: employing the coke-charging tank 4; imparting the friction force onto the coke by using the coke-charging tank 4 to increase the rotation strength of the coke; and then charging the coke into the vertical furnace 6. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a coke filling tank and a vertical furnace operating method in which coke treated using the coke is used in a blast furnace or the like.

  In molten iron production by a blast furnace, massive iron raw materials such as sintered ore and massive ore and massive coke serving as a heat source and reducing material source are charged from the top of the furnace. Then, the high-temperature air blown into the furnace from the tuyeres at the bottom of the furnace gasifies the blow-in reducing material such as coke and fine powder in the furnace to generate high-temperature reducing gas, and the high-temperature gas fills the furnace. The gap between the iron raw material and the coke particles is flowed 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 gaps between the particles are not properly secured, the ventilation resistance in the furnace is increased and abnormal phenomena such as unsuccessful charging and blowout occur, and stable operation cannot be performed. Productivity is reduced. That is, it is very important to ensure the air permeability of the packed bed for blast furnace operation. In particular, in the lower part of the furnace where the iron raw material is melted to form metal slag droplets, the packed bed is made of coke, and the quality of the air permeability greatly affects the operational stability.

  The main coke powder generation area in the blast furnace is in the furnace lower dropping zone and the raceway (see, for example, Non-Patent Document 1). This is presumably because the coke that had undergone reaction degradation in the blast furnace peeled off into brittle parts when subjected to mechanical wear in the moving packed bed or impact in the raceway.

  As a means for suppressing the generation of powder from coke, use of coke having high rotational strength (typically DI150 / 15 defined by JISK2151) can be mentioned. For example, Non-Patent Document 2 describes a reduction in the furnace core powder rate by increasing the coke rotational strength DI150 / 15, and the use of coke with a high rotational strength is effective in improving the air permeability of the blast furnace.

On the other hand, if processing that develops rotational strength can be added from the time coke is produced to the time it is charged into the blast furnace, the margin on the ventilation surface generated by improving the air permeability in the furnace can be increased. It can be transferred to increase, reduction of coke ratio, increase of pulverized coal ratio, etc., and the benefits to enjoy as blast furnace operation are great. As a method for producing high-strength coke, a technique is known in which cold strength is increased by blowing a high-boiling fraction of coal tar into red hot coke discharged from a coke oven (for example, Patent Document 1). reference.).
“Iron and Steel” 82, 1996, p. 641 “Materials and Processes” 6, 1993, p. 848 JP 7-11254 A

  As described above, it is known that the use of coke having a high rotational strength typified by DI150 / 15 defined in JISK2151 is effective in improving the air permeability of the blast furnace. However, coal suitable for producing high-strength coke is generally expensive and disadvantageous in terms of production cost. Therefore, considering the cost increase, there is a limit to the improvement of coke strength by improving the quality of coal used.

  On the other hand, in the technology to increase the cold strength by blowing high-boiling fraction of coal tar into red hot coke discharged from the coke oven, tar pretreatment, blowing equipment, exhaust gas treatment equipment at the blowing location, etc. There is a problem that it is necessary and requires operating costs.

  Therefore, the object of the present invention is to solve such problems of the prior art, and to be charged in a vertical furnace such as a blast furnace without increasing the cost by changing the coking coal, and complicated pretreatment for product coke. Another object of the present invention is to provide a vertical furnace operating method that enables stable vertical furnace operation by suppressing the pulverization of coke in the furnace.

  Another object of the present invention is to provide a coke filling tank used in the above-described method for operating a vertical furnace.

The features of the present invention for solving such problems are as follows.
(1) A vertical coke filling tank installed in the coke conveyance line from the coke oven to the vertical furnace, and a mechanism for charging coke from the upper part of the coke filling tank and discharging the coke from the lower part. And a coke filling tank having a stirring device for stirring the coke in the coke filling tank and applying a frictional force to the coke surface.
(2) A vertical furnace characterized in that, by using the coke filling tank according to (1), a frictional force is applied to the coke, and the rotational strength of the coke is increased and then charged into the vertical furnace. Operation method.
(3) The coke whose rotational strength has been increased by the method described in (2) is charged into a range including a radial center that is a range of 0 to 0.3 in the dimensionless radius of the vertical furnace. A vertical furnace operating method characterized by

  According to the present invention, it is possible to improve the rotational strength of coke without increasing the cost during the production of coke, and contribute to stable operation of the vertical furnace due to a decrease in ventilation resistance. It is possible to obtain the effect of increasing the freedom of vertical furnace operation, such as reducing the ratio and increasing the pulverized coal ratio.

  In order to solve the above-mentioned problems, the present invention suppresses the coke in-furnace pulverization by improving the rotational strength of the coke during the coke conveyance process and charging it into a vertical furnace such as a blast furnace. It is.

  If 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. It was thought that by charging, the rotational strength of coke could be improved and coke pulverization in the furnace could be suppressed. Hereinafter, the present invention will be described as a case where a blast furnace is used as a vertical furnace.

  A dry digestion facility (CDQ) is known as a processing facility before charging blast furnace with coke. This is a facility for the purpose of sensible heat recovery of the produced red hot coke. On the other hand, the effect of increasing the rotational strength is also exhibited by descending the packed bed during the sensible heat recovery process. This effect is believed to be an effect of wear.

  Therefore, it is considered that the rotational strength of the coke can be improved by adding wear to the coke as in the case of CDQ. In the present invention, a vertical coke filling tank of the same scale as the CDQ equipment is installed in the transfer process from the coke oven to the blast furnace, and the rotational strength improvement treatment due to wear during movement in the filling tank is performed between the coke oven and the blast furnace. By doing so, the quality of coke is improved. As long as the rotational strength of the coke at the time of charging the blast furnace increases, the ventilation resistance decreases and contributes to stable operation as described above, while increasing the output, reducing the coke ratio and increasing the pulverized coal ratio, etc. The benefits of blast furnace operation are great.

  As a vertical coke filling tank, for example, the coke is rubbed together using a hopper, and the coke is separated into a lump part and a powdery part by applying a frictional force to the surface of the coke. It is possible to prevent in-furnace pulverization by using the part in a vertical furnace.

  When using the hopper, the coke layered inside the hopper adds a compressive force to the coke below the hopper, and a frictional force is applied when cutting, so that cracks exist not only in the brittle part of the coke surface but also inside the coke. The destruction of coke due to the cause can be promoted, and a larger amount of powdery parts can be generated and separated. When the frictional force and the compressive force are added together, a better effect can be exhibited. In order to increase the compressive force, the hopper can be enlarged to increase the coke stacking height inside the hopper, but an expensive construction cost is required to increase the hopper size.

  Therefore, in the present invention, the coke is separated into a massive part and a powdery part by mainly applying a frictional force to the coke. In order to give frictional force or compressive force to coke, it is only necessary to rub the coke together, so even if it is dropped to a normal hopper etc., a certain effect can be obtained, but to promote pulverization of the fragile part Further, by providing a stirring device for stirring the coke stored in the hopper, it is possible to mainly increase the strength of the coke without adding a frictional force to the coke and increasing the size of the hopper.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 5 is an example of the prior art, and shows a coke conveyance line from the coke oven 1 to the blast furnace 6. FIG. 1 shows an embodiment of the present invention. By providing an arbitrary number of coke filling tanks 4 having a storage and discharge function on the way from the coke oven 1 to the blast furnace 6 in FIG. Rotational strength can be increased by wear when descending. When the CDQ 2 is already installed, it is desirable to install the coke filling tank 4 at an arbitrary location between the CDQ 2 and the blast furnace 6 as shown in FIG. The scale of the coke filling tank 4 is arbitrary, but considering the improvement in rotational strength due to wear in the moving bed, a scale similar to the CDQ with a diameter of 6 to 9 m and a height of 10 to 20 m of the cylindrical portion is desirable.

  FIG. 2 shows an embodiment of the stirring device for the coke filling tank 4, and FIG. 3 shows another embodiment of the stirring device for the coke filling tank 4. The coke filling tank 4 is installed in a coke conveyance line from the coke oven to the blast furnace, and has a mechanism for charging the coke from the upper part of the coke filling tank 4 and discharging the coke from the lower part. A stirring device 10 is provided for stirring the coke and applying a frictional force to the coke surface. In FIG. 2, the stirring device 10 includes a rod 11 and a rotary blade 12, and the coke 13 in the coke filling tank 4 is stirred by rotating the rod 11 as indicated by an arrow to apply a frictional force. Promotes powdering of fragile parts. In FIG. 3, the coke 13 is stirred by the stirring rod 14.

  As ancillary equipment of the coke filling tank 4, as shown in FIGS. 2 and 3, from the lower part of the coke filling tank 4, a transport device such as a bucket conveyor 15 that conveys coke from the upper part of the coke filling tank 4. A device such as a feeder 16 that discharges coke is required. Moreover, in this invention, since powder generate | occur | produces in the coke filling tank 4, it is necessary to remove them, before charging them into a blast furnace. A sieve 17 may be installed in the lower part of the coke filling tank 4, or a sieve may be installed between the coke filling tank 4 and the storage tank (coke storage tank) 5. When a sieve is installed between the coke oven and the storage tank 5, the coke filling tank 4 may be installed on the upstream side of the existing sieve and the existing sieve may be used. Further, a sieve under the existing storage tank 5 may be used. Although it is desirable to process the entire amount of coke conveyed to the blast furnace using the present invention, it is effective even when only a part of the coke is charged into the blast furnace, and the selection of the processing amount is arbitrary. It is.

  When only a part of the coke is treated, it is preferable to charge the coke in a range including a radial central portion which is a range of 0 to 0.3 in the dimensionless radius of the blast furnace. It is known that the core and hearth of a blast furnace are composed of coke charged in the center of the furnace. Pulverization is prevented and high-strength coke is supplied to the furnace center. This will stabilize the blast furnace operation. Accordingly, one of the operation methods is to selectively treat the coke charged to the furnace center according to the present invention.

The present invention was applied to a coke transport line in a blast furnace having an internal volume of 5000 m ³ . In operation with an output of 11000 T / day and a coke ratio of 380 kg / t, 25 mass% of the coke used is a blast furnace through a coke filling tank having a diameter of 9 m and a height of 18 m, similar to that shown in FIG. It was conveyed to. Since CDQ was already installed in this example, the coke filling tank was installed between CDQ and the blast furnace storage tank as shown in FIG.

Coke was sampled on the CDQ exit side and the coke filling tank exit side of the present invention, and the rotational strength DI _150/15 was measured under the same conditions for the operation of the coke oven and the coal used. The results are shown in Table 1.

  It was confirmed that the rotational strength of the coke was improved by processing in the coke filling tank.

  Next, blast furnace operation (operation Nos. 1 to 3) was performed using coke treated in a coke filling tank. Fig. 4 shows the distribution of ore 20 and coke 21 charged in the blast furnace at dimensionless radial positions. Operation No. No. 1 does not perform the treatment in the coke filling tank. When conventional coke is used as the coke 21, the operation No. 1 is performed. 2 and 3 are cases in which only coke 21b in FIG. 4 is treated with coke treated in a coke filling tank, and conventional coke is used for coke 21a. Table 2 shows the blast furnace operation results.

  By applying the present invention, the operation No. No. 1 (comparative example) under the same operating conditions. In 2 (invention example), the ventilation resistance index was reduced. As a result, since the operation was stabilized, the operation No. In operation 3, operation was performed with a reduced coke ratio. Operation No. In operation No. 3, operation No. Low coke ratio operation with a ventilation resistance index equivalent to 1 (comparative example) became possible.

Coke conveyance line (one embodiment of the present invention). One embodiment of the stirring apparatus of a coke filling tank. Another embodiment of the stirring apparatus of a coke filling tank. The graph which shows the distribution in the dimensionless radius position of the ore and coke charged to the blast furnace. Coke transport line (prior art).

Explanation of symbols

1 Coke oven 2 CDQ
DESCRIPTION OF SYMBOLS 3 Wet fire extinguisher 4 Coke filling tank 5 Storage tank 6 Blast furnace 10 Stirrer 11 Rod 12 Rotor blade 13 Coke 14 Stir bar 15 Bucket conveyor 16 Feeder 17 Sieve 20 Ore 21a, b Coke

Claims (3)

  A vertical coke filling tank installed in the coke conveyance line from the coke oven to the vertical furnace, having a mechanism for charging the coke from the upper part of the coke filling tank and discharging the coke from the lower part, A coke filling tank comprising a stirring device for stirring the coke in the coke filling tank to impart a frictional force to the coke surface.   A method for operating a vertical furnace comprising applying a frictional force to coke using the coke filling tank according to claim 1 and increasing the rotational strength of the coke and then charging the vertical furnace.   The coke whose rotational strength is increased by the method according to claim 2 is charged in a range including a radial central portion which is a range of 0 to 0.3 in a dimensionless radius of a vertical furnace. How to operate a vertical furnace.

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