Gas seal structure of rotary kiln

Abstract

To provide a gas seal structure of a rotary kiln which can increase durability even when a rubber member having low heat resistance is used.SOLUTION: Disclosed is a gas seal structure 30 in a rotary kiln 1 comprising: a kiln body 11; an object feed part 2; and a gas discharge part 20. The gas discharge part 20 comprises: an internal structural body 21 with an internal isolation wall 22 provided between the kiln body 11 and a feed pipe 4 of the object feed part 2; and an external structural body 25 with an external isolation wall 26 provided to sandwich the kiln body 11 with the internal isolation wall 22 of the internal structural body 21 and surround the kiln body 11. The gas seal structure 30 comprises: an internal seal part 32 having a labyrinth structure; an external seal part 31; and a cooling gas feed part 35 configured to feed a cooling gas into an external space 25h. A rubber member is used for a member constituting the external seal part 31.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a gas seal structure of a rotary kiln.

Background Art

[0002] There is a rotary kiln as an apparatus for processing objects to be processed such as various powders and producing processed products. The rotary kiln includes a cylindrical kiln body rotatably held and heating means such as a heater for heating the kiln body from the outside. Further, the rotary kiln is provided with a raw material supply section for charging the object to be processed into the kiln body from one end (charging end) of the kiln body, and a discharge section for discharging the processed product is provided at the other end (discharge end) of the kiln body. Further, a gas supply section for supplying an atmosphere gas such as hot air, oxygen gas, or nitrogen gas is provided at the discharge end of the kiln body of the rotary kiln to bring the atmosphere inside the kiln body to a predetermined state. Further, a gas discharge section for discharging the atmosphere gas that has flowed from the discharge end to the charging end inside the kiln body to the outside is provided at the charging end of the kiln body.

[0003] In such a rotary kiln, while the temperature inside the kiln body is raised to a predetermined temperature by the heating means, the object to be processed is supplied into the kiln body from the raw material supply section while the kiln body is rotated. Since the kiln body is installed inclined so that the height of the discharge end is slightly lower than the height of the charging end, the object to be processed supplied into the kiln body moves toward the discharge section while being stirred by the rotation of the kiln body, and is heated while being maintained in a predetermined atmosphere while moving toward the discharge section. Then, the object to be processed becomes a processed product processed to a predetermined state while moving to the discharge section, and the processed product is discharged from the discharge section.

[0004] In such a rotary kiln, in order to maintain a predetermined atmosphere inside the kiln body, it is necessary to prevent the intrusion of outside air. Between the raw material supply section, discharge section, gas supply section, gas discharge section and the kiln body, a sealing structure is provided to block the outside and the inside of the kiln body even when the kiln body rotates. For example, Patent Document 1 discloses providing a sealing structure such as a lip seal structure, a gland packing, or a mechanical seal between the kiln body and a hood provided to cover the kiln body. Further, as shown in FIG. 2, Patent Document 1 provides a circular tube 102 (supply-side circular tube or discharge-side circular tube) having a smaller diameter than the portion for processing the object to be processed at the end of the kiln body 101 in order to improve the sealing performance between the kiln body 101 and the hood 110, and a sealing structure 120 is provided between this circular tube 102 and the hood (supply-side umbrella-shaped cylinder or discharge-side umbrella-shaped cylinder).

[0005] In addition, Patent Document 1 also discloses a configuration in which the hood (supply-side umbrella-shaped cylinder or discharge-side umbrella-shaped cylinder) has a double-tube structure having an inner tube inserted into a tubular portion with a smaller diameter (supply-side circular tube or discharge-side circular tube) and an outer tube provided to cover the supply-side circular tube. And Patent Document 1 discloses that by providing a sealing portion between each tube (inner tube and outer tube) and the circular tube (supply-side circular tube or discharge-side circular tube) and supplying an atmosphere gas to the space surrounded by the sealing portion, the outer tube and the inner tube, the sealing reliability can be enhanced.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, although the technique disclosed in Patent Document 1 can enhance the sealing function between the kiln body and the hood, since the members constituting the seal structure are in contact with high-temperature atmospheric gas and reaction-generated gas, the members constituting the seal structure deteriorate due to use and need to be replaced regularly. In particular, when the seal material has a rubber member with low heat resistance, the seal material deteriorates early and needs to be replaced in a short period. On the other hand, since a rubber seal material has low heat resistance but excellent flexibility and a high sealing effect, there is a demand for a seal structure that can be used without replacement for a long period even when a rubber seal material with low heat resistance is used.

[0008] In view of the above circumstances, an object of the present invention is to provide a gas seal structure for a rotary kiln that can improve durability even when using a member made of rubber with low heat resistance.

Means for Solving the Problems

[0009] The gas seal structure of the rotary kiln of the first invention has a kiln body for heating an object to be processed, an object supply unit having a supply pipe for loading the object to be processed from the charging side end of the kiln body, and a gas discharge unit for discharging gas from the inside of the kiln body from the charging side end of the kiln body. The gas discharge unit has an internal structure body having an internal partition wall provided between the kiln body and the supply pipe of the object supply unit so as to surround the supply pipe of the object supply unit, and an external partition wall provided between the internal partition wall of the internal structure body so as to sandwich and surround the kiln body. An external structure body in which an external space surrounded by the external partition wall and the internal partition wall of the internal structure body is hermetically separated from an internal space inside the internal partition wall of the internal structure body, and a discharge pipe for discharging gas from the internal space of the internal structure body to the outside of the external structure body. The gas seal structure includes an internal seal part having a labyrinth structure for sealing between the internal partition wall of the internal structure body and the inner surface of the kiln body, an external seal part for sealing between the outer surface of the kiln body and the external partition wall of the external structure body, and a cooling gas supply part for supplying cooling gas into the external space. It is characterized in that a rubber member is used for the member constituting the external seal part. The gas seal structure of the rotary kiln of the second invention is characterized in that, in the first invention, the external seal part of the gas seal structure is provided so as to be located outside the internal seal part with respect to the kiln body. The gas seal structure of the rotary kiln of the third invention is characterized in that, in the first or second invention, the internal seal part has an annular member provided so as to surround the internal partition wall of the internal structure body, and the annular member is provided so as to have a gap between its inner surface and the outer surface of the internal partition wall of the internal structure body and / or between its outer surface and the inner surface of the external partition wall of the external structure body. The gas seal structure of the rotary kiln of the fourth invention is characterized in that, in the third invention, the cooling gas supply part supplies the cooling gas in an amount that generates a differential pressure such that gas does not leak through the gap from the inside of the internal space to the outside of the internal space between the inside of the external space and the inside of the internal space.

Advantages of the Invention

[0010] According to the first invention, the gas discharge part has an external structure having an internal space in an internal structure communicated with the kiln body and an external space hermetically separated from the internal space, and a labyrinth structure is adopted for the internal seal part between the internal structure and the supply pipe of the object supply part for loading the object to be processed. Therefore, the airtightness between the kiln body and the outside can be improved. Moreover, since the external seal part is not contacted by the atmospheric gas or the like, and a cooling gas is supplied to the external space facing the external seal part, even if a seal structure having a rubber member is adopted for the external seal part, the durability of the rubber member can be increased, so that the durability of the external seal part can also be increased. According to the second invention, it is easy to prevent damage to the external seal part due to heat. According to the third and fourth inventions, while maintaining the sealing performance of the internal seal part, the structure of the internal seal part can be simplified.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0012] The gas seal structure of the rotary kiln of the present embodiment is a structure for sealing between the kiln body and the outside in a rotary kiln for processing an object to be processed, and is characterized in that a member made of rubber having low heat resistance is used to improve durability.

[0013] <Rotary Kiln 1> As shown in FIG. 1, the rotary kiln 1 employing the gas seal structure of the present embodiment includes a kiln body 11 for heat-treating an object to be processed. This kiln body 11 is a structure having a processing space 11h surrounded by a cylindrical wall 11a. This kiln body 11 is provided so as to incline downward from the charging end where the object to be processed is supplied from the object supply unit 2 described later toward the discharge end where the processed object processed in the processing space 11h is discharged. This kiln body 11 is rotatably supported by a support device (not shown) and is configured to be rotated by a drive device (not shown). Further, a heating unit such as a heater (not shown) for heating the kiln body 11 is provided around the cylindrical wall 11a of the kiln body 11.

[0014] As shown in FIG. 1, a charging end wall 11b for closing the charging end is provided at the charging end of the kiln body 11. A supply-side tubular portion 12 that communicates between the processing space 11h and the outside and has a diameter shorter than that of the kiln body 11 is provided on this charging end wall 11b. The supply pipe 4 of the object supply unit 2 is inserted into the supply-side tubular portion 12 from its tip opening, and a hopper 3 for supplying the object to be processed to the supply pipe 4 is provided at the base end of this supply pipe 4. Further, a charging conveyor 5 for conveying the object to be processed supplied from the hopper 3 into the kiln body 11 is provided inside the supply pipe 4.

[0015] <Gas discharge unit 20> Also, as shown in FIG. 1, a gas discharge unit 20 is provided between the kiln body 11 and the object supply unit 2. This gas discharge unit 20 is a device for discharging gas such as hot air, oxygen gas, nitrogen gas, etc. in the atmosphere gas supplied into the processing space 11h of the kiln body 11 from a gas supply unit (not shown) and reactive gas generated in the process of processing the object to be processed. This gas discharge unit 20 has an internal structure 21, an external structure 25, and a gas seal structure 30.

[0016] <Internal structure 21> As shown in FIG. 1, the internal structure 21 includes an internal partition wall 22 disposed between the inner surface of the supply-side tubular portion 12 of the kiln main body 11 and the outer surface of the supply pipe 4 of the object supply unit 2. This internal partition wall 22 is provided so as to surround the supply pipe 4 of the object supply unit 2 and form a gap between its inner surface and the outer surface of the supply pipe 4. The tip of this internal partition wall 22 is provided so as to be located near the charging end wall 11b of the kiln main body 11 or within the processing space 11h of the kiln main body 11. On the other hand, a seal member 23 for hermetically sealing the space between the outer surface of the supply pipe 4 is provided at the base end of the internal structure 21. That is, an internal space 21h surrounded by the internal partition wall 22, the internal structure 21, the supply pipe 4, and the seal member 23 is formed within the internal structure 21. A discharge pipe 21s for communicating between the inside of the internal space 21h and the outside is provided in this internal partition wall 22. This discharge pipe 21s penetrates the external partition wall 26 of the external structure 25 described later and is provided so as to be located outside the external partition wall 26.

[0017] <External structure 25> As shown in FIG. 1, the external structure 25 includes an external partition wall 26 provided so as to sandwich the supply-side tubular portion 12 of the kiln main body 11 between it and the internal partition wall 22 of the internal structure 21. This external partition wall 26 is provided so as to surround the supply-side tubular portion 12 of the kiln main body 11 and form a gap between its inner surface and the outer surface of the supply-side tubular portion 12 of the kiln main body 11. The tip of this external partition wall 26 is provided so as to be located near the outer surface of the charging end wall 11b of the kiln main body 11. The base end of this external partition wall 26 is connected to the outer surface of the supply pipe 4 by a base end wall 27. That is, an external space 25h surrounded by the external partition wall 26, the supply-side tubular portion 12 of the kiln main body 11, and the base end wall 27 and hermetically isolated from the internal space 21h of the internal structure 21 is formed within the external structure 25.

[0018] <Gas seal structure 30> As shown in FIG. 1, the gas seal structure 30 includes an external seal portion 31, an internal seal portion 32, and a cooling gas supply portion 35.

[0019] <External seal portion 31> As shown in FIG. 1, the external space 25h of the external structure 25 communicates with the external space through a space 30a between the inner surface of the tip of the external partition wall 26 of the external structure 25 and the outer surface of the supply-side tubular portion 12 of the kiln body 11. An external seal portion 31 for sealing the space between the inner surface of the tip of the external partition wall 26 of the external structure 25 and the outer surface of the supply-side tubular portion 12 of the kiln body 11 is provided in this space 30a. That is, an external seal portion 31 for isolating the outside from the external space 25h of the external structure 25 is provided. This external seal portion 31 airtightly closes the space between the two. This external seal portion 31 has a known seal structure using a rubber member. The external seal portion 31 can adopt, for example, a seal structure such as a lip seal structure, a gland packing, or a mechanical seal.

[0020] <Internal seal portion 32> As shown in FIG. 1, the processing space 11h of the kiln main body 11 communicates with the external space 25h of the external structure 25 through the space 30b between the outer surface of the internal partition wall 22 of the internal structure 21 and the inner surface of the supply-side tubular portion 12 of the kiln main body 11. An internal seal portion 32 for sealing the space between the outer surface of the internal partition wall 22 of the internal structure 21 and the inner surface of the supply-side tubular portion 12 of the kiln main body 11 is provided in this space 30b. That is, an internal seal portion 32 for isolating the processing space 11h of the kiln main body 11 and the external space 25h of the external structure 25 is provided. This internal seal portion 32 has a labyrinth structure. Specifically, the internal seal portion 32 has an annular member 33 provided so as to surround the internal partition wall 22 of the internal structure 21. The outer cylindrical surface 33b of this annular member 33 is fixed to the inner surface of the supply-side tubular portion 12 of the kiln main body 11. Moreover, the annular member 33 is provided so that a gap 33h is formed between its inner surface 33a and the outer surface of the internal partition wall 22 of the internal structure 21. That is, a gap 33h for communicating between the external space 25h inside the external structure 25 and the processing space 11h inside the kiln main body 11 is formed in the annular member 33. This gap 33h is provided so that a predetermined pressure loss occurs in the gas passing through the gap 33h. For example, this gap 33h is provided to be 1 to 20 mm.

[0021] <Cooling gas supply section 35> As shown in FIG. 1, the gas seal structure 30 includes a cooling gas supply section 35 for supplying cooling gas to the external space 25h of the external structure 25. The cooling gas is not particularly limited, and examples thereof include air and oxygen.

[0022] As described above, the tip of the supply-side tubular portion 12 of the kiln main body 11 communicating with the processing space 11h of the kiln main body 11 is disposed within the external space 25h of the external structure 25, and the external space 25h of this external structure 25 is isolated from the outside by the external seal portion 31 of the gas seal structure 30. An internal structure 21 for discharging the atmosphere gas of the processing space 11h of the kiln main body 11 to the outside is provided within the external space 25h of this external structure 25, and the internal space 21h of the internal structure 21 and the external space 25h of the external structure 25 are hermetically isolated. Moreover, between the external space 25h of the external structure 25 and the processing space 11h of the kiln main body 11, they are isolated by the internal seal portion 32 of the gas seal structure 30. With such a structure, it is possible to prevent the external seal portion 31 from directly contacting the atmosphere gas. Therefore, even if a known seal structure using a rubber member is adopted for the external seal portion 31, the durability of the rubber member can be increased, and thus the durability of the external seal portion 31 can be increased.

[0023] Further, since the internal seal portion 32 for sealing between the external space 25h of the external structure 25 and the processing space 11h of the kiln main body 11 has a labyrinth structure, the sealing performance can be maintained at a certain level without using a rubber member. Moreover, since the labyrinth structure is formed only by installing the annular member 33, while simplifying the structure of the internal seal portion 32, a predetermined sealing performance can be exhibited.

[0024] <Regarding the gas seal structure 30> The relative positions of the external seal portion 31 and the internal seal portion 32 of the gas seal structure 30, that is, their relative positions in the axial direction of the supply-side tubular portion 12 of the kiln body 11 are not particularly limited. However, it is desirable to provide the external seal portion 31 so as to be positioned outward (to the right in FIG. 1) of the internal seal portion 32 with respect to the kiln body 11. If arranged in such a position, in the supply-side tubular portion 12 of the kiln body 11, the position where it contacts the external seal portion 31 becomes a portion that forms the external space 25h. Since this portion comes into contact with the cooling gas, the temperature can be kept lower compared to the portion where the atmospheric gas contacts. Therefore, it becomes easier to prevent damage to the external seal portion 31 due to heat.

[0025] In the above-described example, the case where the annular member 33 of the internal seal portion 32 has its outer surface 33b fixed to the inner surface of the supply-side tubular portion 12 of the kiln body 11 and a gap is formed between its inner surface 33a and the tip outer surface of the internal partition wall 22 of the internal structure 21 has been described. However, the annular member 33 of the internal seal portion 32 may be provided such that its inner surface 33a is fixed to the tip outer surface of the internal partition wall 22 of the internal structure 21 and a gap is formed between its outer surface 33b and the inner surface of the supply-side tubular portion 12 of the kiln body 11.

[0026] Also, in the above-described example, the case where one annular member 33 is provided for the internal seal portion 32 has been described, but a plurality of internal seal portions 32 may be provided along the axial direction (the left-right direction in FIG. 1) of the supply-side tubular portion 12 of the kiln body 11. When providing a plurality of annular members 33, it is desirable to provide the plurality of annular members 33 such that gaps are alternately formed along the axial direction of the supply-side tubular portion 12. That is, in adjacent annular members 33, one annular member 33 is provided so as to have a gap on the side of the internal partition wall 22 of the internal structure 21 (that is, between the inner surface 33a of the annular member 33 and the outer surface of the internal structure 21), and the other annular member 33 is provided so as to have a gap on the side of the supply-side tubular portion 12 of the kiln body 11 (that is, between the outer surface 33b of the annular member 33 and the inner surface of the external partition wall 26 of the external structure 25).

[0027] <Regarding the cooling gas supply portion 35> The amount (flow rate) of the cooling gas supplied from the cooling gas supply unit 35 to the external space 25h is not particularly limited. It is sufficient to supply the cooling gas in an amount that causes a differential pressure such that the atmospheric gas or the like does not leak from the processing space 11h into the external space 25h between the inside of the external space 25h of the external structure 25 and the inside of the processing space 11h of the kiln body 11 through the gap 33h.

[0028] Further, the external structure 25 may have a structure for discharging the cooling gas to the outside so that the inside of the external space 25h does not exceed a predetermined pressure when the cooling gas is supplied by the cooling gas supply unit 35. By providing such a structure, it is possible to prevent the cooling gas from flowing into the processing space 11h of the kiln body 11 and changing the processing atmosphere of the object to be processed.

[0029] <Regarding the kiln body 11> In the above-described example, the case where the supply-side tubular portion 12 is provided at the charging end of the kiln body 11 has been described. However, the kiln body 11 does not necessarily have to have the supply-side tubular portion 12. When the supply-side tubular portion 12 is not provided, the internal structure 21 may be configured such that the tip of the internal partition wall 22 is located in the processing space 11h of the kiln body 11, and the cylindrical wall 11a of the kiln body 11 is located between the outer surface of the internal partition wall 22 of the internal structure 21 and the tip of the external partition wall 26 of the external structure 25. In this case, the internal seal portion 32 of the gas seal structure 30 may be provided between the inner surface of the cylindrical wall 11a of the kiln body 11 and the outer surface of the supply pipe 4 of the object supply unit 2, and the external seal portion 31 may be provided between the outer surface of the cylindrical wall 11a of the kiln body 11 and the inner surface of the external partition wall 26 of the external structure 25.

Industrial Applicability

[0030] The gas seal structure of the rotary kiln of the present invention is suitable as a gas seal structure for a rotary kiln that requires discharging atmospheric gas, reactive gas, or the like to the outside from the processing space of the kiln body.

Explanation of Reference Numerals

[0031] 1 Rotary kiln 2 Object supply unit 3 Hopper 4 Supply pipe 5 Loading conveyor 5 11 Kiln body 11h Processing space 20 Gas discharge unit 21 Internal structure 21h Internal space 22 Internal partition wall 25 External structure 25h External space 26 External partition wall 30 Gas seal structure 31 External seal part 32 Internal seal part 33 Annular member 35 Cooling gas supply unit

Claims

1. A rotary kiln gas seal structure having a kiln body for heating an object to be processed, an object supply unit having a supply pipe for loading the object to be processed from the charging side end of the kiln body, and a gas discharge unit for discharging gas from the charging side end of the kiln body to the inside of the kiln body, wherein the gas discharge unit has an internal structure body having an internal partition wall provided so as to surround the supply pipe of the object supply unit between the kiln body and the supply pipe of the object supply unit, has an external partition wall provided so as to sandwich and surround the kiln body between the internal partition wall of the internal structure body, and an external space surrounded by the external partition wall and the internal partition wall of the internal structure body is hermetically separated from the internal space within the internal partition wall of the internal structure body, the gas seal structure has an internal seal portion having a labyrinth structure for sealing between the internal partition wall of the internal structure body and the inner surface of the kiln body, an external seal portion for sealing between the outer surface of the kiln body and the external partition wall of the external structure body, and is composed of a cooling gas supply unit for supplying a cooling gas into the external space, and a rubber member is used for a member constituting the external seal portion characterizing the gas seal structure of the rotary kiln.

2. The external seal portion of the gas seal structure is provided so as to be located outside the internal seal portion with respect to the kiln body characterizing the gas seal structure of the rotary kiln according to claim 1.

3. The internal seal portion has an annular member provided so as to surround the internal partition wall of the internal structure body, and the annular member is provided so as to have a gap between its inner surface and the outer surface of the internal partition wall of the internal structure body and / or between its outer surface and the inner surface of the external partition wall of the external structure body characterizing the gas seal structure of the rotary kiln according to claim 1 or 2.

4. The cooling gas supply unit supplies the cooling gas in an amount that generates a differential pressure such that gas does not leak through the gap from the inside of the internal space between the inside of the external space and the inside of the internal space characterizing the gas seal structure of the rotary kiln according to claim 3.

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