JP2013170779A - Cooling structure for rotary kiln - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling structure for a rotary kiln, capable of extending, with respect to a rotary kiln shell body under high-temperature operation, the period until a first repair or replacement is needed after the operation start, or the life of a kiln end of the rotary kiln shell body by efficiently cooling the kiln end of the rotary kiln having a high thermal load.SOLUTION: A cooling structure for a rotary kiln includes: a hollow cylindrical shell body; a heat transfer fin formed on the outer circumferential surface of the shell body; and a cooling water storage portion disposed at a position through which the heat transfer fin is passed according to the rotation of the shell body. The kiln end is cooled with cooling water in the cooling water storage device.

Description

  The present invention relates to a cooling structure for a rotary kiln.

  For example, ISP and smelting methods can be used to remove fluorine and chlorine in crude zinc oxide dust collected by a reduction culture kiln or rotary hearth furnace that volatilizes and reduces valuable metals such as zinc contained in steelmaking electric furnace dust and blast furnace dust. A rotary kiln having a hollow cylindrical rotary furnace is widely used in order to reduce the grade to be usable as an oxide ore raw material for a zinc smelter employing an electrolytic smelting method.

  In particular, the smelting ore for electrolytic smelting has a fluorine content to suppress the progress of corrosion of the aluminum permanent cathode used in the electrowinning process, and a chlorine content to prevent elution of lead in the anode. Needs to be reduced to several hundred ppm. Since most of chlorine and fluorine contained in the raw material are lead chlorofluoride, it is necessary to maintain and control the calcination temperature at 1100 to 1150 ° C. in order to decompose this. For this reason, a very high heat load is applied to the furnace end that is the discharge part of the rotary kiln, and therefore, the furnace end of the rotary kiln is required to have high heat resistance.

  In addition, this furnace end may discharge high-temperature fired products, and the surrounding area is often exposed to particularly high heat, so this part is an irregular refractory that can be easily applied to the outer periphery of the shell body. There is also a method of coating. However, unlike the inner peripheral side, the irregular refractory is difficult to fix because there is no gap between the refractories, and it is difficult to install the refractory sufficiently thick. Has been proposed.

  For example, as a furnace end part structure of a rotary kiln with improved heat resistance, an air-cooled furnace end structure in which a cooling space is formed at the furnace end part (see Patent Document 1), or a furnace end part having a water cooling structure A furnace end structure of a rotary kiln that improves heat resistance has been proposed by adding some cooling structure to the kiln body separately (see Patent Document 2).

JP 2001-227870 A JP-A-9-287718

  However, the air-cooled outlet side structure described in Patent Document 1 has a complicated structure because an air cooling path is formed in the rotating shell body itself, and the cooling effect is insufficient due to air cooling. On the other hand, in the case of the water-cooled outlet side structure described in Patent Document 2, the structure is complicated because a water channel is formed in the rotating shell body itself, and safety considerations such as measures against water leakage are required.

  The present invention solves the above-mentioned problems and efficiently cools the rotary kiln furnace end, which is subjected to high heat load, with a simple structure, so that the rotary kiln shell main body under high temperature operation is repaired or replaced for the first time from the start of operation. It is an object of the present invention to provide a cooling structure of a rotary kiln that can extend the period until the time is required, that is, the life of the rotary kiln shell body.

  The present inventors provide a cooling structure for a rotary kiln with a heat transfer protrusion provided circumferentially on the outer peripheral surface in the vicinity of the furnace end of the shell body of the rotary kiln, within a cooling water storage device arrangement disposed below the shell body. It is found that the end of the rotary kiln shell that is subjected to high heat load can be efficiently cooled by adopting a structure that directly cools with the cooling water of this, which can extend the life of the rotary kiln shell body under high temperature operation. The invention has been completed. More specifically, the present invention provides the following.

  (1) A cooling structure of a rotary kiln, which is a hollow cylindrical shell body, a heat transfer fin formed on an outer peripheral surface of the shell body, and a position through which the heat transfer fin passes as the shell body rotates. A cooling structure for a rotary kiln comprising a cooling water storage section disposed on the rotary kiln.

  (2) The rotary kiln cooling structure according to (1), wherein the heat transfer fin is formed in a bowl shape on a plane parallel to the kiln rotation direction along the outer periphery of the shell body.

  (3) The cooling structure of the rotary kiln according to (1), wherein the heat transfer fin is formed in a bowl shape on a plane orthogonal to the kiln rotation direction along the outer periphery of the shell body.

  (4) The rotary kiln cooling structure according to any one of (1) to (3), wherein the heat transfer fin is formed in the vicinity of a furnace end of the shell body.

  In the present invention, the cooling structure of the rotary kiln is a structure in which the heat transfer fin formed circumferentially on the outer peripheral surface of the shell body is directly cooled by the cooling water in the cooling water reservoir disposed below the shell body. It was. As a result, the rotary kiln can be efficiently cooled with a simple structure, and the life of the rotary kiln shell body can be extended in the heating operation using a rotary kiln for drying and firing, etc. Can increase the sex.

It is a cross-sectional schematic diagram which shows the whole structure and usage mode of a rotary kiln provided with the cooling structure of this invention. It is the front view and cross-sectional schematic diagram of the shell main-body part and the heat-transfer fin which comprise the cooling structure in one Embodiment of the rotary kiln of this invention. It is the typical fragmentary enlarged view for demonstrating the front view of a shell main-body part and the heat-transfer fin which comprise the cooling structure in other embodiment of the rotary kiln of this invention, a heat transfer fin, and the fin shape seen from C direction. is there.

  Hereinafter, although embodiment of this invention is described, this invention is not limited to the following embodiment at all. Hereinafter, an embodiment in which the cooling structure of the present invention is applied to a large-sized rotary kiln for drying and firing intended for metal purification will be described. However, the cooling structure of the present invention is a cylindrical rotary heating furnace. It can be applied to the furnace end of any other heating furnace.

<Rotary kiln>
First, with reference to FIG. 1, an overall configuration and usage mode of a rotary kiln 1 which is an embodiment of the cooling structure of the present invention will be described. As shown in FIG. 1, the rotary kiln 1 includes a shell body 10, heat transfer fins 20 formed in a bowl shape on the circumference of the outer periphery of the shell body 10, a cooling water storage unit 30 disposed below the shell body 10, A burner section 40 that blows hot air for heating the inside of the shell body 10, a drive gear 50 that transmits a rotational force in the R direction in the figure to the shell body 10, and a shell body for preventing diffusion of exhaust gas etc. The rotary heating furnace includes a fixed hood 60 formed so as to cover the furnace end and a kiln support (not shown) that supports the shell body 10. In use, the shell body 10 is usually 1 with respect to a horizontal plane in a direction in which the material to be fired moves from an input port 11 serving as an input port for the material to be fired toward a discharge port 12 for discharging the material to be fired. Installed with ~ 4% slope.

  The shell body 10 is a kiln made of a hollow cylindrical structure made of carbon steel (ordinary structural steel) having a thickness of 15 to 30 mm, and a refractory for improving heat resistance is provided on the inner peripheral wall surface. Is preferably installed. In the shell body 10, the periphery on the discharge port 12 side for discharging the high-temperature fired product is often exposed to particularly high heat. Therefore, the heat transfer fins 20 are provided near the furnace end or the furnace end on the discharge port 12 side. It is preferable. About the shape of the heat transfer fin formed in a bowl shape on the circumference, shapes such as the heat transfer fin 20A shown in FIG. 2, the heat transfer fin 20B shown in FIG. Details of the heat transfer fins 20 and the cooling water reservoir 30 will be described later.

  In the rotary kiln 1 having the above-described configuration, the inside of the shell body 10 is heated to a high temperature by the burner unit 40 and the shell body 10 is rotated in the R direction by the drive gear 50, while the object to be fired is a Throw in the direction. The object to be baked moves along the inclination of the shell body 10 while being stirred and baked, and moves in the shell body 10 toward the discharge port 12. From the discharge port 12, a high-temperature fired product is discharged in the b direction. Is done. Further, the vicinity of the discharge port 12 is also exposed to the radiant heat of the flame from the burner section 40, sulfurous acid gas generated from the fuel, and corrosive gas generated in the furnace. For this reason, the peripheral edge of the discharge port 12, that is, the furnace end of the shell body 10, is exposed to a particularly strong heat load or corrosive gas.

  In this way, in the rotary kiln 1 that is exposed to a harsh environment, particularly at the furnace end, the overall configuration includes the heat transfer fins 20 and the cooling water storage unit 30 and has a novel configuration that has not been achieved in the past. The feature of the present invention is that the life of the furnace end of the rotary kiln 1 can be greatly extended with a simple structure.

<Cooling structure of rotary kiln>
Next, the cooling structure of the rotary kiln 1 of the present invention will be described with reference to FIGS. 1 and 2. Fig.2 (a) is a front view of the shell main body 10 and the heat transfer fin 20A which comprise the cooling structure in one Embodiment of the rotary kiln of this invention, FIG.2 (b) is sectional drawing in the AA line | wire. It is.

  As shown in FIGS. 2A and 2B, the heat transfer fin 20A is a protruding structure formed on the outer peripheral surface of the shell body 10 so that the shell body 10 can be cooled by cooling water. As shown in FIG. 1, the shell body 10 is formed on the outer peripheral surface so that at least a part thereof passes through the cooling water 31 stored in the cooling water storage section 30 as the shell body 10 rotates. .

  The heat transfer fin 20A is a protruding structure made of a metal having high thermal conductivity. The material is not particularly limited as long as it has a thermal conductivity sufficient to exhibit the cooling effect of the shell body 10 by the cooling water. However, carbon steel (ordinary structure) can be used because it is easy to process and costs can be reduced. Steel) can be preferably used.

  The shape of the heat transfer fin 20 is not necessarily limited to a specific shape. For example, as shown in FIGS. 2A and 2B, the shape of the shell body 10 extends along the circumference of the outer periphery of the shell body 10. What is formed in a bowl shape on a plane parallel to the rotation direction R can be given as a preferred example. By making the heat transfer fin into a shape like the heat transfer fin 20 </ b> A, a part of the heat transfer fin 20 is always kept in contact with the cooling water 31, and the cooling effect on the shell body 10 can be enhanced.

  The shape of the heat transfer fin 20A is not limited to the ring shape as shown in FIG. 2, and various modifications can be made to increase the heat transfer area. For example, it is possible to freely apply deformation for enlarging or reducing the contact area with the cooling water, such as making the surroundings uneven, thereby obtaining a desired cooling effect. Those having such shaped fins are also a preferred embodiment of the present invention and are within the scope of the present invention.

  As shown in FIGS. 3A to 3C, the shape of the heat transfer fin 20 is a bowl shape on a plane perpendicular to the rotation direction R of the shell body 10 along the outer periphery of the shell body 10. It can also be formed. Fig.3 (a) is a front view of the shell main body 10 and the heat transfer fin 20 which comprise the cooling structure in other one Embodiment of the rotary kiln of this invention, FIG.3 (b) is in the BB line | wire. It is sectional drawing. Moreover, FIG.3 (c) is a typical fragmentary enlarged view for demonstrating the shape at the time of seeing the heat-transfer fin 20 from the C direction of a figure. By forming the heat transfer fins in the shape of the heat transfer fins 20 </ b> B, the heat transfer fins 20 move in the cooling water storage unit 30, so that deposits due to dust and the like remain in the center of the cooling water storage unit 30. Can be prevented. Furthermore, as will be described later, in the case where the cooling water reservoir 30 is a bowl-shaped water channel that circulates the cooling water 31, the heat transfer fins 20 can appropriately promote the inflow and outflow of the cooling water 31. .

  In addition, about the cooling effect in the case of making the heat-transfer fin 20 into the shape as shown in FIG. The contact area of 31 can be freely adjusted, and thereby a desired cooling effect can be obtained.

  Although the installation position of the heat transfer fin 20 is not particularly limited as long as it is the outer periphery of the shell body 10, as shown in FIG. 1, it is preferable to install the heat transfer fin 20 at or near the furnace end where a particularly high heat load is applied. Thereby, the cooling effect with respect to the shell main body 10 can be heightened more than the case where the heat-transfer fin 20 is installed in another position. Further, the heat transfer fins 20 are not limited to a single installation form as shown in FIGS. A desired cooling effect can be obtained by adopting a multiple installation form in which a plurality of heat transfer fins are appropriately provided. One having such multiple heat transfer fins is also a preferred embodiment of the present invention and is within the scope of the present invention.

  The cooling water storage unit 30 is a component that stores the cooling water 31. As the shell body 10 rotates, at least a part of the water surface side of the cooling water 31 needs to be open so that at least a part of the heat transfer fins 20 is immersed in the cooling water 31, but other parts As for, the shape is not particularly limited as long as the required amount of cooling water 31 can be stored or circulated. The bowl-shaped thing which stores the cooling water 31 may be sufficient, or the bowl-shaped water channel which can recirculate the cooling water 31 may be sufficient.

  The cooling water reservoir 30 is disposed at a position through which the heat transfer fins 20 pass as the shell body 10 rotates. More specifically, at the time of the rotation, at least a part of the heat transfer fins 20 is disposed at a position that passes through the cooling water 31 stored in the cooling water storage unit 30. Although it is preferable to install the heat transfer fins 20 near the furnace end, in this case, the cooling water reservoir 30 is disposed inside the fixed hood 60 to effectively cool the portion with the highest heat load. I can do it.

  In order to cope with the position fluctuation of the heat transfer fin 20 due to expansion and contraction of the metallic shell main body 10 in the direction of the rotation axis, the cooling water reservoir 30 has the above-described rotation axis about the open surface on the water surface side of the cooling water 31. It is preferable that the expansion width is greater than the expected width of the direction. Further, particularly when such a fluctuation range is large, for example, the cooling water storage unit 30 may be movably installed on a rail laid in the rotation axis direction so that it can be appropriately moved to a desired range. It can be mentioned as an example of a preferred embodiment of the invention.

  According to the above cooling structure of the rotary kiln, the following effects can be obtained.

  (1) Since the shell body of the rotary kiln is subjected to an extremely high heat load, damage due to the heat load is likely to occur. Accordingly, the cooling structure of the rotary kiln of the present invention is arranged at a position where the hollow cylindrical shell main body, the heat transfer fin formed on the outer peripheral surface of the shell main body, and the heat transfer fin pass as the shell main body rotates. And a cooling water reservoir. Thereby, the shell main body of the rotary kiln which requires a high heat load can be effectively cooled while having a simple structure that is easy to manufacture. Therefore, the life of the rotary kiln shell body is extended, the frequency of repairs due to thermal damage is reduced, and the productivity of operations using the rotary kiln can be significantly increased.

  (2) The cooling structure of the rotary kiln has a structure in which the heat transfer fins are formed in a bowl shape on a plane parallel to the kiln rotation direction along the outer periphery of the shell body. Thereby, the contact time between the heat transfer fin and the cooling water can be maximized. Therefore, the productivity of the operation using the rotary kiln can be further enhanced with a higher cooling effect.

  (3) The cooling structure of the rotary kiln has a structure in which the heat transfer fins are formed in a bowl shape on a plane orthogonal to the kiln rotation direction along the outer periphery of the shell body. Thereby, the arrangement | positioning space | interval of a heat-transfer fin can be adjusted suitably, and a cooling effect can be adjusted appropriately. Further, it is possible to prevent accumulation of dust and other deposits from staying in the central portion of the cooling water reservoir, and to appropriately promote inflow and outflow of cooling water. Therefore, it is possible to adjust the cooling effect more appropriately according to the operation conditions, and it is possible to further increase the productivity of the operation using the rotary kiln.

  (4) The cooling structure of the rotary kiln has a structure in which heat transfer fins are formed in the vicinity of the furnace end of the shell body. As a result, the vicinity of the furnace end where a particularly high heat load is applied can be intensively cooled. Therefore, the productivity of the operation using the rotary kiln can be further enhanced with a higher cooling effect.

  As mentioned above, although embodiment of this invention was described, this invention is not restricted to embodiment mentioned above. The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

  As a more specific example, when the cooling structure of the rotary kiln of the present invention is applied to a conventional rotary kiln, for example, in the mode shown in FIGS. 1 and 2, the operation of the conventional rotary kiln is about every six months. The period from the start of operation of the rotary kiln to the start of repair requiring operation interruption can be extended to about twice as long. Thus, the rotary kiln cooling structure of the present invention can significantly increase the productivity of the rotary kiln by extending the life of the rotary kiln shell body.

DESCRIPTION OF SYMBOLS 1 Rotary kiln 10 Shell main body 11 Input port 12 Discharge port 20 Heat transfer fin 30 Cooling water storage part 31 Cooling water 40 Burner part 50 Drive gear 60 Fixed hood

Claims (4)

The cooling structure of the rotary kiln,
A hollow cylindrical shell body;
Heat transfer fins formed on the outer peripheral surface of the shell body;
The cooling structure of a rotary kiln provided with the cooling water storage part arrange | positioned in the position where the said heat-transfer fin passes with rotation of the said shell main body.   The cooling structure of the rotary kiln according to claim 1, wherein the heat transfer fin is formed in a bowl shape on a plane parallel to the kiln rotation direction along the outer periphery of the shell body.   The cooling structure for a rotary kiln according to claim 1, wherein the heat transfer fin is formed in a bowl shape on a plane perpendicular to the kiln rotation direction along the outer periphery of the shell body.   The rotary kiln cooling structure according to claim 1, wherein the heat transfer fin is formed in the vicinity of a furnace end of the shell body.

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