Rotation shaft seal structure

Abstract

To provide a rotation shaft seal structure which can be used under high pressure without requiring a maintenance for a long time.SOLUTION: A seal structure includes: a first seal member 25 for sealing a gap between a rotor 23 and a casing 21; a second seal member 26 positioned on an outer side of the first seal member 25 and for sealing a gap between a rotation shaft 24 and the casing 21; a steam introduction space 212 in which the steam from a steam inlet port 211 is introduced; and a condensation pressure-reduction chamber 216 which cools by the coolant from a coolant inlet port 214. The introduction of steam from the steam inlet port 211 to the steam introduction space 212 allows the steam introduction space 212 to have the pressure equivalent to or higher than the pressure in a pressurizing space 22, and prevents materials and steam in the pressurizing space 22 from transferring into the steam introduction space 212 and prevents a leakage of steam to outside of the casing 21 by condensing and pressure-reducing the steam leaked from the second seal member 26 in the condensation pressure-reduction chamber 216.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a rotary shaft seal structure of a device having a rotating body that rotates integrally with a rotary shaft in a pressurized space pressurized by steam.

Background Art

[0002] Conventionally, a rotary valve for transferring raw materials to the inlet of a pressurized cooking device has been known (for example, Patent Document 1 below). Since the rotary valve has high airtightness, raw materials can be transferred to the inlet while maintaining the pressure inside the pressurized cooking device. In the rotary valve, a rotating body (vanes and side walls) rotates integrally with the rotary shaft inside the casing. Also, in a device that employs a screw device for conveying raw materials as the main body of the pressurized cooking device, a rotating body (screw vanes) rotates integrally with the rotary shaft inside the casing of the device.

[0003] In both the rotary valve and the screw device, the rotary shaft penetrates the casing, and the space between the casing and the rotary shaft is sealed with a sealing member such as a gland packing to ensure airtightness. More specifically, by sealing with the sealing member, raw materials and steam inside the rotary valve and the screw device are prevented from leaking outside the casing. For this reason, in both the rotary valve and the screw device, sealing between the casing and the rotary shaft has been indispensable.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since seal members such as gland packings harden after a certain period of time and their sealing performance deteriorates, it was necessary to replace the seal members regularly. For this reason, in a pressure cooking apparatus that performs cooking with high-pressure steam, the frequency of maintenance also increases. In addition, there was a limit to improving the sealing performance with only a sealing structure in which a seal member is interposed between the casing and the rotating shaft as described above.

[0006] The present invention solves the above-described conventional problems, and an object thereof is to provide a rotating shaft seal structure that can cope with use under pressure, particularly use under high pressure, and does not require long-term maintenance.

Means for Solving the Problems

[0007] In order to achieve the above object, a rotating shaft seal structure of the present invention is a rotating shaft seal structure of an apparatus having a rotating body that rotates integrally with a rotating shaft in a pressurized space pressurized by steam, the rotating shaft, the rotating body, a casing through which the rotating shaft passes, a first seal member that seals between the rotating shaft or the rotating body and the casing, a second seal member that is located outside the first seal member in the axial direction of the rotating shaft and seals between the rotating shaft or the rotating body and the casing, a steam inlet provided in the casing, a steam inlet space that is located between the first seal member and the second seal member in the axial direction of the rotating shaft and is provided so as to surround the rotating shaft or the rotating body in the casing and into which steam from the steam inlet is introduced, a refrigerant inlet provided in the casing, and a condensation decompression chamber that is located outside the second seal member in the axial direction of the rotating shaft and is provided so as to surround the rotating shaft or the rotating body in the casing and is cooled by refrigerant from the refrigerant inlet. By introducing steam from the steam inlet into the steam inlet space, the pressure in the steam inlet space is made equal to or higher than the pressure in the pressurized space to prevent the raw materials and steam in the pressurized space from moving to the steam inlet space side, and by condensing and decompressing the leaked steam that has leaked from the second seal member in the condensation decompression chamber, leakage of steam to the outside of the casing is prevented.

Advantages of the Invention

[0008] According to the rotating shaft seal structure of the present invention, in addition to the first seal member and the second seal member, by providing a steam injection space and a condensation decompression chamber, leakage of raw materials and steam to the outside of the casing can be prevented. As a result, the rotating shaft seal structure of the present invention can cope with use under high pressure and eliminates the need for long-term maintenance.

[0009] Specifically, by injecting steam from the steam injection port into the steam injection space, the steam injection space is made to have the same pressure or higher than the pressurized space, thereby preventing the raw materials and steam in the pressurized space from moving to the steam injection space side. Further, even if steam leaks from the second seal member, this leaked steam is condensed and decompressed in the condensation decompression chamber to become steam condensation drain and is discharged, so that direct leakage of steam to the outside of the casing can be prevented.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0011] The present invention relates to a rotary shaft seal structure of an apparatus having a rotating body that rotates integrally with a rotary shaft in a pressurized space pressurized by steam. There is no particular limitation on the type of apparatus that employs this rotary shaft seal structure. For example, as an apparatus that employs the same structure, there are a rotary valve that transfers raw materials to the inlet of a pressurized cooking apparatus, a screw apparatus that conveys cooked raw materials, a conveyor apparatus, and the like.

[0012] In the present embodiment, first, an embodiment in which the rotary shaft seal structure according to the present invention is employed in a rotary valve will be described with reference to FIGS. 1, 2, and 3. Next, an embodiment in which the rotary shaft seal structure according to the present invention is employed in a screw apparatus will be described with reference to FIGS. 4 and 5.

[0013] FIG. 1 shows a configuration diagram of a pressurized cooking apparatus 1 to which the rotary shaft seal structure according to an embodiment of the present invention is applied. The pressurized cooking apparatus 1 cooks raw materials (for example, cereal raw materials) in a steam atmosphere under pressure. An input rotary valve 13 is attached to the raw material inlet 121 of the screw apparatus 12 of the pressurized cooking apparatus 1, and an output rotary valve 14 is attached to the raw material outlet 122.

[0014] The input rotary valve 13 includes a rotor 132 formed by a rotary shaft 24, blades 231, and side walls 232 (see FIG. 2) and a plurality of pockets 133 formed by the rotor 132 in a casing 131, and the rotor 132 rotates in the casing 131. The output rotary valve 14 has a similar configuration and includes a casing 141, a rotor 142, and pockets 143.

[0015] The screw device 12 is provided with a screw 124 for conveying raw materials inside a casing 123. The screw 124 has screw blades 1241 attached to a rotating shaft 1242. A joint portion 1242a of the rotating shaft 1242 is connected to a motor (not shown), which is a power source, via a joint (not shown). The screw device 12 is provided with a pressurized steam supply port 125, and pressurized steam is injected into the casing 123 from the pressurized steam supply port 125 (arrow b). As a result, the raw materials are pressure-cooked in a steam atmosphere inside the casing 123.

[0016] In FIG. 1, the raw materials are supplied toward the input rotary valve 13 (arrow a), and the raw materials supplied to the input rotary valve 13 are supplied to the opened pockets 133. Subsequently, by the rotation of the rotor 132, they are transferred toward the input port 121, pass through the input port 121, and are input toward the screw 124. By the rotation of the screw 124, the raw materials are conveyed horizontally, and after being input to the discharge port 122, they are discharged by being transferred by the discharge rotary valve 14.

[0017] In the pressure-cooking device 1 shown in FIG. 1, when pressurized steam is injected into the casing 123 from the pressurized steam supply port 125, the inside of the casing 123 becomes a pressurized space pressurized by the steam. Along with this, a part of the inside of the casing 131 of the input rotary valve 13 connected to the screw device 12 also becomes a pressurized space pressurized by the steam. Similarly, a part of the inside of the casing 141 of the discharge rotary valve 14 also becomes a pressurized space pressurized by the steam.

[0018] Although not shown in FIG. 1, in the input rotary valve 13, the rotating shaft 24 (see FIG. 2) penetrates the casing 131. The same applies to the discharge rotary valve 14. As described above, the inside of each casing of the screw device 12, the input rotary valve 13, and the discharge rotary valve 14 becomes a pressurized space pressurized by the steam. Therefore, in order to prevent the raw materials and steam from leaking outside the casing, a sealing structure is required between the rotating shaft or the rotating body and each casing.

[0019] Specifically, if the raw material in the form of water candy leaks from the gap between the rotating shaft or the rotating body and the casing, the raw material will adhere to the rotating shaft or the rotating body and the casing, so maintenance for removing the raw material is required. In addition, the leakage of steam outside the casing and the fall of the condensed water formed by the leakage of steam outside the device may damage the environment around the equipment. Even if these problems are solved by adopting a seal member, the seal member hardens and the seal performance deteriorates, so periodic replacement is required. In addition, when the device is used under high pressure, it may not be possible to ensure the seal performance. The rotating shaft seal structure according to the present invention can also be used under high pressure and does not require maintenance for a long time. Hereinafter, it will be described in detail with reference to FIG. 2.

[0020] FIG. 2 is a cross-sectional view showing a rotating shaft seal structure 2 according to an embodiment of the present invention, and corresponds to a cross-sectional view taken along line AA of the input rotary valve 13 shown in FIG. 1 (a cross-sectional view in the central axis direction of the rotor 132). The rotating shaft seal structure 2 also has the structure of the input rotary valve 13 and the discharge rotary valve 14 shown in FIG. 1, but for the sake of convenience of explanation, it will be described as the rotating shaft seal structure 2. However, for simplicity, the rotor is not shown in cross-section. Hereinafter, in FIG. 2, the structure on one side of the pair of rotating shafts 24 will be described, but the structure on the other side of the rotating shaft 24 is the same.

[0021] The rotating shaft seal structure 2 is externally configured by a casing 21, and a pressurized space 22 is formed inside the casing 21. Inside the casing 21, a rotating body 23 that rotates inside the pressurized space 22 is provided. The rotating body 23 is composed of blades 231 and side walls 232 provided at both ends of the blades 231. The rotating body 23 rotates integrally with the rotating shaft 24. The rotating shaft 24 penetrates the casing 21.

[0022] Between the side wall 232 and the casing 21, it is sealed by the first seal member 25. Between the rotating shaft 24 and the casing 21, it is sealed by the second seal member 26. That is, in the axial direction of the rotating shaft 24, the second seal member 26 is located outside the first seal member 25.

[0023] Examples of the materials of the first seal member 25 and the second seal member 26 include fluororesin, fluororesin containing glass, and PEEK (Poly Ether Ether Ketone) resin.

[0024] The casing 21 is provided with a steam inlet 211, a steam inlet space 212, and a steam drain outlet 213. The steam inlet space 212 is located between the first seal member 25 and the second seal member 26 in the axial direction of the rotating shaft 24, and is provided so as to surround the rotating shaft 24. Steam from the steam inlet 211 is introduced into the steam inlet space 212 (arrow e), and the condensed steam drain is discharged from the steam drain outlet 213 (arrow f).

[0025] The casing 21 incorporates a water-cooled jacket 27. The water-cooled jacket 27 is located outside the second seal member 26 in the axial direction of the rotating shaft 24. The water-cooled jacket 27 is a cylindrical body, and a space 271 is formed inside the cylindrical body. Refrigerant from the refrigerant inlet 214 provided in the casing 21 is introduced into the space 271 (arrow g). The refrigerant introduced into the space 271 is discharged from the refrigerant outlet 215 provided in the casing 21 (arrow h).

[0026] A condensation decompression chamber 216 is formed so as to surround the rotating shaft 24 in the space inside the water-cooled jacket 27 which is a cylindrical body. The inside of the condensation decompression chamber 216 is cooled by the water-cooled jacket 27 through which the refrigerant introduced from the refrigerant inlet 214 flows. Although details will be described later, leaked steam leaking from the second seal member 26 flows into the condensation decompression chamber 216, and this leaked steam is condensed and decompressed in the condensation decompression chamber 216 and discharged from the steam condensation drain outlet 217 (arrow i).

[0027] Although not shown in Fig. 2, in order to improve the heat exchange efficiency between the condensation decompression chamber 216 and the water-cooled jacket 27, the condensation decompression chamber 216 may have a structure with fins inside. Also, in the embodiment shown in Fig. 2, indirect cooling is adopted to cool the inside of the condensation decompression chamber 216 by the water-cooled jacket 27, but it is not limited to this. For example, a structure in which a refrigerant such as water is directly introduced into the condensation decompression chamber 216 may also be used.

[0028] The rotating shaft seal structure 2 configured as described above is a structure for preventing the raw material and steam from leaking outside the casing 21. This will be specifically described below with reference to Fig. 2.

[0029] In Fig. 2, a motor (not shown), which is a power source, is connected to the joint portion 24a of the rotating shaft 24 via a coupling (not shown). When the rotating shaft 24 is rotationally driven by the motor, the rotating body 23 rotates within the pressurized space 22. Therefore, the raw material is introduced into the rotating shaft seal structure 2 (arrow c), passes through the rotating body 23, and is discharged from the rotating shaft seal structure 2 (arrow d).

[0030] The inside of the pressurized space 22 is pressurized by steam. For this reason, there is a possibility that the raw material in a water-ame state may leak in the direction of the rotating shaft 24 through the gap between the casing 21 and the side wall 232. This leakage is mainly prevented by the first seal member 25 and the steam introduction space 212.

[0031] Specifically, by introducing steam from the steam inlet 211 into the steam introduction space 212, the steam introduction space 212 is made to have the same pressure or higher than that of the pressurized space 22, preventing the raw material and steam in the pressurized space 22 from moving to the steam introduction space 212 side. That is, in addition to the first seal member 25, by providing the steam introduction space 212, leakage of the raw material and steam from the pressurized space 22 can be prevented.

[0032] On the one hand, in this embodiment, since steam is introduced into the steam introduction space 212, if there is no sealing structure outside the steam introduction space 212, the steam in the steam introduction space 212 will leak out of the casing 21 along the rotating shaft 24. This leakage is prevented by the second seal member 26, the condensation decompression chamber 216, and the oil seal 218.

[0033] By providing the second seal member 26, it is possible to suppress the steam in the steam introduction space 212 from leaking outside the second seal member 26. The leaked steam from the second seal member 26 is condensed and decompressed in the condensation decompression chamber 216 to become steam condensation drain, and is discharged from the steam condensation drain outlet 217 (arrow i). Therefore, it is possible to prevent the leaked steam from the second seal member 26 from leaking outside the casing 21.

[0034] In this embodiment, an oil seal 218 is provided outside the condensation decompression chamber 216. However, since the pressure inside the condensation decompression chamber 216 is close to atmospheric pressure, the outside of the condensation decompression chamber 216 can be sufficiently sealed with a simple seal such as the oil seal 218. In other words, even if the oil seal 218 is not provided, it is possible to prevent the leaked steam from leaking outside the casing 21, so a configuration without the oil seal 218 may be used.

[0035] According to the above, the rotating shaft seal structure 2 includes the steam introduction space 212 and the condensation decompression chamber 216 in addition to the first seal member 25, the second seal member 26, and the oil seal 218, thereby preventing the raw material and steam from leaking outside the casing 21. As a result, the rotating shaft seal structure 2 can also be used under high pressure and does not require maintenance for a long period of time.

[0036] As described above, one embodiment of the present invention has been explained. However, the above embodiment is an example and may be appropriately modified. FIG. 3 is a cross-sectional view showing another embodiment of the rotating shaft seal structure 2. In FIG. 2, the first seal member 25 is interposed between the casing 21 and the side wall 232 constituting the rotating body 23. However, as shown in FIG. 3(a), the first seal member 25 may be interposed between the casing 21 and the rotating shaft 24. The same applies to the case of a structure without the side wall 232.

[0037] Also, as shown in FIG. 3(b), the first seal member 25, the second seal member 26, and the steam injection space 212 may be interposed between the casing 21 and the side wall 232 constituting the rotating body 23. Further, in FIG. 2, the condensation decompression chamber 216 is provided so as to surround the rotating shaft 24. However, as shown in FIG. 3(c), it may be provided so as to surround the side wall 232 constituting the rotating body 23.

[0038] FIG. 4 is a cross-sectional view showing a rotating shaft seal structure 2' according to another embodiment of the present invention. The rotating shaft seal structure 2' is also the structure of the screw device 12 shown in FIG. 1. However, for the sake of convenience of explanation, it will be described as the rotating shaft seal structure 2'. However, for simplicity, the screw is not shown in cross-section. In the rotating shaft seal structure 2' shown in FIG. 4, those having the same configuration as the rotating shaft seal structure 2 shown in FIG. 2 are given the same numbers and the description is appropriately omitted.

[0039] The rotating shaft seal structure 2' has an appearance formed by the casing 21, and a pressurized space 22 is formed inside the casing 21. Inside the casing 21, a rotating body 28 (screw blade) that rotates inside the pressurized space 22 is provided. The rotating body 28 rotates integrally with the rotating shaft 29. The rotating shaft 29 penetrates the casing 21.

[0040] In FIG. 4, a motor (not shown), which is a power source, is connected to the joint portion 29a of the rotating shaft 29 via a joint (not shown). When the rotating shaft 29 is rotationally driven by the motor, the rotating body 28 rotates within the pressurized space 22. Therefore, the raw material is introduced into the rotating shaft seal structure 2' (arrow j), conveyed horizontally by the action of the rotating body 28, and discharged from the rotating shaft seal structure 2' (arrow k).

[0041] FIG. 5 shows an enlarged view of the main part of the rotating shaft seal structure 2' shown in FIG. 4. Hereinafter, among both ends of the rotating shaft 29, the structure on one end side will be described, but the structure on the other end side is the same. In FIG. 5, the inside of the pressurized space 22 is pressurized by steam. For this reason, there is a possibility that the raw material in a water-like state leaks outside the casing 21 through the gap between the casing 21 and the rotating shaft 29. This leakage is mainly prevented by the first seal member 25 and the steam introduction space 212.

[0042] Specifically, by introducing steam from the steam inlet 211 into the steam introduction space 212, the steam introduction space 212 is made to have the same pressure or higher than the pressurized space 22, preventing the raw material and steam in the pressurized space 22 from moving to the steam introduction space 212 side. That is, in addition to the first seal member 25, by providing the steam introduction space 212, similar to the rotating shaft seal structure 2, leakage of the raw material and steam from the pressurized space 22 can be prevented.

[0043] On the other hand, also in this embodiment, since steam is introduced into the steam introduction space 212, if there is no seal structure outside the steam introduction space 212, the steam in the steam introduction space 212 leaks outside the casing 21 along the rotating shaft 29. These leakages are prevented by the second seal member 26, the condensation decompression chamber 216, and the oil seal 218, similar to the rotating shaft seal structure 2.

[0044] By providing the second seal member 26, it is possible to suppress the leakage of the steam in the steam introduction space 212 to the outside of the second seal member 26. The leaked steam leaking from the second seal member 26 is condensed and depressurized in the condensation and depressurization chamber 216 to become steam condensation drain, and is discharged from the steam condensation drain outlet 217 (arrow i). Therefore, it is possible to prevent the leaked steam from the second seal member 26 from leaking to the outside of the casing 21.

[0045] Similar to the above-described embodiment shown in FIGS. 2 and 3, in the present embodiment, an oil seal 218 is provided outside the condensation and depressurization chamber 216. However, since the pressure inside the condensation and depressurization chamber 216 is close to the atmospheric pressure, the outside of the condensation and depressurization chamber 216 can be sufficiently sealed with a simple seal such as the oil seal 218. In other words, even if the oil seal 218 is not provided, since it is possible to prevent the leaked steam from leaking to the outside of the casing 21, a configuration in which the oil seal 218 is omitted may be employed.

[0046] According to the above, the rotating shaft seal structure 2' includes, like the rotating shaft seal structure 2, in addition to the first seal member 25, the second seal member 26, and the oil seal 218, a steam introduction space 212 and a condensation and depressurization chamber 216, thereby preventing the raw material and steam from leaking to the outside of the casing 21. As a result, the rotating shaft seal structure 2' can also be used under high pressure and does not require maintenance for a long period of time.

[0047] The apparatus provided with the rotating shaft seal structure according to the present invention can cope with the pressure as described above, and in particular, can also be used under high pressure. Specifically, it can be used at 1.00 MPaG or less. Generally, it is considered difficult to seal the rotating shaft under a high pressure of 0.30 to 1.00 MPaG. However, according to the rotating shaft seal structure of the present invention, even in such a high pressure condition, it is possible to prevent the raw material and steam from leaking to the outside of the casing, and there is no need for maintenance for a long period of time. Therefore, the rotating shaft seal structure of the present invention can exhibit more advantages when used under a high pressure of 0.30 to 1.00 MPaG.

[0048] In addition, the rotational speed of the device equipped with the rotating shaft seal structure according to the present invention is not particularly limited. Generally, a labyrinth seal is used for the seal member of the rotating shaft of a high-speed rotating device, but the labyrinth seal is not suitable for a low-speed rotating device with a rotational speed of about several hundred revolutions per minute (rpm). As devices adopting the same structure, the rotary valve for transferring raw materials to the inlet of the pressurized cooking device, the screw device for conveying the cooked raw materials, and the conveyor device, which were described above, are devices that operate at a low rotational speed of 500 rpm or less. By applying the rotating shaft seal structure of the present invention, more advantages can be demonstrated.

Explanation of Signs

[0049] 1 Pressurized cooking device 2, 2’ Rotating shaft seal structure 21 Casing 211 Steam inlet 212 Steam inlet space 213 Steam drain outlet 214 Refrigerant inlet 215 Refrigerant outlet 216 Condensation and decompression chamber 217 Steam condensation drain outlet 218 Oil seal 22 Pressurized space 23 Rotating body 231 Blade 232 Side wall 24 Rotating shaft 25 First seal member 26 Second seal member 27 Water-cooled jacket 28 Rotating body 29 Rotating shaft

Claims

【Claim 1】 A rotary shaft seal structure of an apparatus having a rotating body that rotates integrally with a rotary shaft in a pressurized space pressurized by steam, comprising: the rotary shaft; the rotating body; a casing through which the rotary shaft passes; a first seal member that seals between the rotary shaft or the rotating body and the casing; a second seal member that is located outside the first seal member in the axial direction of the rotary shaft and seals between the rotary shaft or the rotating body and the casing; a steam inlet provided in the casing; a steam inlet space that is located between the first seal member and the second seal member in the axial direction of the rotary shaft, is provided so as to surround the rotary shaft or the rotating body in the casing, and into which steam from the steam inlet is introduced; a refrigerant inlet provided in the casing; a condensation decompression chamber that is located outside the second seal member in the axial direction of the rotary shaft, is provided so as to surround the rotary shaft or the rotating body in the casing, and is cooled by refrigerant from the refrigerant inlet; and when steam is introduced from the steam inlet into the steam inlet space, the steam inlet space is made to have a pressure equal to or higher than that of the pressurized space to prevent the raw material and steam in the pressurized space from moving to the steam inlet space side, and the leaked steam leaking from the second seal member is condensed and decompressed in the condensation decompression chamber to prevent steam from leaking to the outside of the casing. A rotary shaft seal structure characterized by this.

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