JP5254412B2 - Rotating shaft seal device - Google Patents

Description

  The present invention relates to a shaft seal device for a rotating shaft that penetrates a wall of a container, and more particularly to a shaft seal device for a rotating shaft in a stirrer that rotates at high speed under reduced pressure.

  In various fields such as chemistry, food, medical medicine and energy, a stirrer is widely used for kneading, drying and granulating powder materials. In a general stirrer, a material is loaded into a cylindrical stirring vessel, and the material is stirred by rotating a stirring blade provided on the bottom surface around a rotating shaft. In order to improve the kneading efficiency and the accuracy of granulation, many have side stirring blades such as chopper blades.

The stirrer may be connected to a decompression device for drying the material in a decompressed atmosphere, or may be connected to a spray device for adding a solvent. In order to dry or melt granulate at a high temperature, a stirring / heating container may be provided in the stirring vessel.
Moreover, when processing the material which is easy to oxidize, it may be processed by filling the stirring vessel with an inert gas such as N ₂ gas.

  A stirring blade and a chopper blade for stirring the material are rotationally driven by a rotating shaft connected to a driving mechanism provided outside the stirring container. Since the rotating shaft passes through the bottom and side surfaces of the container, the rotating shaft is provided with a sealing mechanism that isolates the inside and the outside of the stirring container, and prevents the material powder from biting around the shaft. Conventionally, a contact-type sealing material such as a gland packing or an oil seal is used for the sealing mechanism. However, when the sealing material comes into contact with the rotating shaft that rotates at a high speed, the sealing material is worn out, and there is a problem that the wear powder is mixed into the stirring vessel.

In particular, in the medical medicine field and fine chemical field, slight contamination due to abrasion powder of the sealing material adversely affects the quality of the product, and thus generation of abrasion powder is a major obstacle to the use of a stirrer. When the loaded material is abrasive powder or the like, the sealing material is polished by a rotating shaft that rotates at high speed, and a lot of wear powder is generated, so that contamination becomes remarkable. Moreover, the wear of the sealing material is accelerated, resulting in inconvenience such as frequent replacement of the sealing material.
When an oil seal is used for the seal mechanism, grease and oil used for lubrication are mixed into the material, so that the material of the lubrication oil may be restricted or the lubrication oil may not be used.

  Therefore, there may be a case in which a non-contact type air seal is used for the shaft seal portion of the rotating shaft. FIG. 5 is a sectional view of a shaft seal device using a conventional air seal. A stirring blade is provided in the stirring vessel, and the stirring blade is connected to a drive device (not shown) by a rotary shaft to form a stirrer. The rotating shaft is provided with a seal mechanism. In the sealing mechanism, an air chamber is provided around the rotation shaft, and a slight gap is provided between the rotation shaft and the stirring vessel wall so that the air chamber and the stirring vessel are communicated to form an air seal.

  In conventional air seals, compressed air is fed into the air chamber from the air supply pipe to form an air flow that blows from the air chamber to the stirring vessel through the gap between the seals, and the material powder that attempts to enter the shaft seal is By pushing back to the stirring container, the mixing of the material powder into the shaft seal is prevented. In the air seal structure of this embodiment, since the rotating shaft and the seal portion are not in contact with each other, the wear of the seal does not occur, and the wear powder does not enter the stirring vessel. Moreover, since grease and oil are not exposed to the material, the lubricant does not adhere to the material and the quality of the product does not deteriorate.

  On the other hand, the air chamber and the stirring container are shaft-sealed by an air seal. In order to maintain the airtightness of the air chamber, a contact-type seal is used for the shaft sealing portion on the drive device side, that is, the side opposite to the stirring container. Therefore, it is not possible to exclude the possibility that the seal material is worn at the shaft seal portion on the drive device side, and the abrasion powder gets on the airflow flowing from the air chamber to the stirring container and enters the stirring container. Further, when an oil seal is used as the contact seal, there is a possibility that the evaporated and scattered lubricating oil may be mixed into the stirring container due to heat and rotational energy generated from the rotating shaft rotating at high speed.

  Furthermore, when the stirrer is operated in a reduced pressure atmosphere, if the contact-type sealing material is worn out and the sealing performance is deteriorated, the air may flow from the sealing portion and the negative pressure may be impaired. When an operation is performed by filling an inert gas in order to process a material that easily oxidizes, if air flows from the seal portion, oxygen may be supplied to the stirring vessel and the material may ignite, which is very dangerous.

  In order to solve this problem, Patent Document 1 discloses a shaft seal device for a rotating shaft that uses an air seal and prevents contamination of foreign matters caused by loss or wear of the shaft seal material. As shown in FIG. 6, in the shaft seal device of the rotary shaft described in Patent Document 1, an air chamber is provided in a seal mechanism provided in the shaft seal portion of the rotary shaft connected to the rotary blade, and there are few air chambers and stirring containers. It communicates with a gap. An exhaust system including a vacuum ejector is connected to the air chamber, and the outside of the air chamber is sealed with an oil seal.

  In the shaft seal device of the prior art described in Patent Document 1, the air chamber existing between the stirring container and the oil seal is set to a negative pressure to isolate the stirring container and the oil seal. For this reason, wear powder and oil splashes generated by friction between the contact-type oil seal and the rotating shaft are sucked together with the air in the air chamber by the vacuum pump and discharged to the exhaust system, and foreign matter is mixed into the stirring container. Will not be contaminated.

  However, since the air chamber communicating with the stirring vessel is evacuated, the material powder is sucked from the stirring vessel into the air chamber and discharged from the exhaust system. Therefore, a loss occurs in the material and a bag filter must be provided in the exhaust system, resulting in an increase in equipment cost and running cost.

Further, since the material powder flows from the stirring container into the air chamber, for example, when the material powder has stickiness, the intruded powder may block the shaft seal portion. When the material powder is an abrasive material, there is a problem that the rotating shaft and the container wall are worn in the air seal gap and the sealing performance is deteriorated. Furthermore, there is a concern that the quality of the product may be deteriorated due to the material powder that has entered the gap is changed in frictional heat due to contact with the rotating shaft that rotates at a high speed and mixed with the object to be processed.
These problems are not limited to the stirrer, but commonly occur in various powder processing apparatuses having a rotating shaft penetrating the container wall, such as a reaction apparatus, a granulating apparatus, and a kneading apparatus that dislike mixing of materials and foreign substances. .

JP 2008-51160 A

  Therefore, the problem to be solved by the present invention is to prevent the contact-type seal wear powder from being mixed in the container in the shaft seal device of the rotating shaft that penetrates the wall of the container in a stirrer and the like. An object of the present invention is to provide a shaft seal device for a rotary shaft that can prevent the powder of the material from entering the seal mechanism.

In order to solve the above problems, the shaft seal device of the rotary shaft of the present invention is a first non-contact type from the container side with respect to the rotary shaft that penetrates the wall of the container of the powder processing device that operates under reduced pressure. A seal, a first air chamber, a second non-contact type seal, a second air chamber, and a first contact type seal are arranged in this order, and the second air chamber exceeds the pressure of the container. while it is operating so as to pressure, characterized in that in order to maintain higher than the gas pressure in the gas pressure and the second air chamber gas pressure in the vessel in the first air chamber.

  According to the shaft seal device of the rotating shaft of the present invention, the first air chamber is maintained at a pressure higher than that of the container and the second air chamber, so that the gas is discharged from the first non-contact seal and the second non-contact seal. Ejection and an air seal are formed. The first non-contact type seal prevents the material powder from being mixed into the shaft seal from the container, and the second non-contact seal is a case where the wear powder generated from the contact type seal is caused by the first air chamber and its tip. To prevent it from entering the container.

  Therefore, both the loss of the raw material powder due to the material powder entering the shaft seal portion and the contamination of the product due to the contact-type seal wear powder mixed into the material can be prevented.

  The first air chamber may be supplied with gas via a lantern ring having a ring-shaped groove opened on the outer periphery and provided with a plurality of holes on the inner peripheral wall. The lantern ring has a function of evenly distributing the gas supplied from the air supply system around the rotating shaft. By using the lantern ring, it is possible to avoid the possibility that the function of the air seal is impaired because the airflow is concentrated in the vicinity of the air outlet of the air supply system and the airflow is not distributed to the part away from the air outlet.

  Further, for a powder processing apparatus that operates under reduced pressure, it is preferable that the second air chamber be operated so as to have a pressure equal to or higher than the pressure of the container. In addition, the first vacuum device may be connected to the container, and the second vacuum device may be connected to the second air chamber so that the container and the second air chamber are decompressed independently.

  In a powder processing apparatus such as a stirrer, when processing a powder in a reduced pressure atmosphere by connecting a vacuum apparatus to the container, most of the gas supplied to the first air chamber flows out into the container according to the pressure difference, The amount of gas flowing into the second air chamber may be insufficient. If it does so, a 2nd non-contact seal may lose a function, and there exists a possibility that the abrasion powder discharge | released from a contact seal may pass a 2nd non-contact seal and may mix in a container.

  Therefore, even when the powder processing apparatus is operated in a reduced-pressure atmosphere, the gas pressure in the second air chamber is set to be higher than that in the first air chamber in order not to deteriorate the function of the first non-contact seal located on the container side. It is preferable to operate so as to be appropriately low and not lower than the gas pressure of the container. In this case, the exhaust system of the second air chamber is connected to a vacuum device that decompresses the container, and a throttle or a relief valve is inserted into the exhaust system so that the gas pressure in the second air chamber does not become lower than the pressure of the container. This adjustment is convenient because it is not necessary to provide a control device for managing the gas pressure.

Note that a second vacuum device different from the first vacuum device for depressurizing the container is connected to the second air chamber so that the gas pressure in the container and the second air chamber can be adjusted independently of each other. Good.
Since the pressure in the container changes depending on the evaporation amount of the raw material, the pressure loss due to the clogging of the bag filter, the state of peripheral equipment such as a vacuum device, etc., the second air chamber is provided by an independently provided second vacuum device. Stable sealing performance can be secured by controlling the pressure.

  Furthermore, when the first non-contact type seal, the first air chamber, and the second non-contact seal are unitized and formed so as to be removed as a unit, the material before and after the change can be removed by removing the unit and washing it when switching the material. Therefore, it is not necessary to disassemble and clean the entire bearing portion as in the prior art, and the labor for cleaning the equipment is greatly reduced.

It is a system flow figure in one example of the present invention. It is an expanded sectional view of the shaft seal device of a present Example. It is a top view of packing. It is sectional drawing of the shaft seal apparatus of the stirrer in the other Example of this invention. It is sectional drawing of the shaft seal apparatus using the conventional type air seal. It is sectional drawing of the shaft seal apparatus of a rotating shaft by another prior art.

  Hereinafter, a shaft seal device for a rotating shaft according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system flow diagram in one embodiment of the present invention. In this embodiment, the shaft seal device for a rotating shaft according to the present invention is applied to a high-speed stirrer. A stirring blade 2 is provided on the bottom surface of the container 1 of the stirrer, and the stirring blade 2 is connected to a driving device 4 by a rotating shaft 3. A pressure gauge 5 and a bag filter 6 are provided on the upper portion of the container 1. A vacuum pipe 36 connected to a vacuum device such as a vacuum pump 7 is connected via a bag filter 6.

  Around the rotating shaft 3, in order from the container 1 side, a first air seal using a first air seal ring 8, a first air chamber 9, a second air seal using a second air seal ring 10, a second air chamber 11, An oil seal 12 is disposed. An air supply system 34 is connected to the first air chamber 9, and a flow meter 13, a pressure adjustment valve 14, and a pressure gauge 15 are incorporated in the air supply system 34. The air supply system 34 is connected to a compressed air source.

  An exhaust system 35 is connected to the second air chamber 11, and a pressure gauge 16, a flow meter 17, a throttle valve 18, a check valve 19, a gate valve 20, and a gate valve 21 are incorporated in the exhaust system 35. . The exhaust system 35 is connected to the vacuum pipe 36 through the gate valve 20 and is depressurized by the vacuum pump 7.

FIG. 2 is an enlarged cross-sectional view of the shaft seal device of this embodiment. A first air seal formed by a first air seal ring 8, a first air chamber 9, and a second air seal formed by a second air seal ring 10 are loaded in the air seal casing 22 around the rotary shaft 3 in this order from the rotary blade 2 side. The oil seal 12 is disposed so as to be sandwiched between the ring-shaped air seal retainers 23, and the oil seal 12 held by the oil seal casing 24 is disposed below the air seal retainer 23.
A ring-shaped packing 25 is inserted between the air seal casing 22 and the oil seal casing 24, and the second air chamber 11 partitioned by these and the rotary shaft 3 is formed.

  Pressurized gas is supplied from the air supply system 34 to the first air chamber 9 via the lantern ring 26 and the air supply holes 27. The air supply holes 27 are formed in and communicated with the air seal casing 22, the air seal retainer 23, the oil seal casing 24, and the packing 25, respectively.

  The lantern ring 26 is a metal ring having a ring-shaped groove on the outer periphery and a plurality of outlet holes provided on the inner peripheral wall at substantially equal intervals. The outlet of the air supply hole 27 opens at the position of the groove on the outer peripheral portion. Thus, the pressurized gas can be supplied uniformly over the entire circumference of the first air chamber 9.

  An exhaust pipe 28 is opened in the second air chamber 11, and the other end of the exhaust pipe 28 is connected to an exhaust system 35. The shaft seal device portion is fixed by a bearing casing 29 and a bearing retainer 31 fixed to the bearing casing 29 with fixing bolts 30.

  The first air seal ring 8 and the second air seal ring 10 are made of fluororesin and surround the rotary shaft 3 with a gap of about 0.2 to 1.0 mm. The oil seal 12 is made of synthetic rubber, fluororubber, fluororesin, or the like, and lubricating oil is applied to the contact portion with the rotating shaft 3.

FIG. 3 is a plan view of a packing having a function of securing the space of the second air chamber. The packing 25 is provided with a through hole at the position of the air supply hole 27 and a notch portion reaching the inner periphery corresponding to the position of the exhaust pipe 28 to secure the internal volume of the second air chamber 11. A passage for discharging the gas in the second air chamber 11 is formed in the exhaust pipe 28.
Further, the packing 25 is provided with a bolt hole 33 through which the fixing bolt 32 is passed.

  Bolt holes are also provided in the air seal casing 22 and the air seal retainer 23, and the air seal casing 22, the air seal retainer 23, and the packing 25 are passed through the fixing bolt 32 from the container 1 side in the same manner as shown in FIG. Thus, the air seal portion is detachably fixed by being screwed into a nut provided in the oil seal casing 24.

In the shaft seal device of the rotating shaft of the present embodiment, a gas having a pressure higher than the pressure in the container 1 and the second air chamber 11 is supplied from the air supply system 34 to the first air chamber 9, and the container from the first air chamber 9 is supplied. The shaft seal of the first air seal ring 8 and the second air seal ring 10 is maintained by the high-pressure gas flowing into the first and second air chambers 11. Compressed air is usually used as the gas to be supplied, but N ₂ gas or the like can be used when the container 1 is operated in an inert gas atmosphere.

  In the gap between the rotary shaft 3 and the first air seal ring 8, an air flow is always generated from the first air chamber 9 toward the container 1, so that the powder that has approached the first air seal ring 8 from within the container 1 is 1 is pushed back into the gap of the first air seal ring 8. Similarly, since an air flow is generated from the first air chamber 9 toward the second air chamber 11 in the gap between the rotating shaft 3 and the second air seal ring 10, the splashes and friction of the lubricating oil generated from the oil seal 12 are generated. Powder does not enter the first air chamber 9. The generated splashes and friction powder flow out from the exhaust pipe 28 to the exhaust system 35 together with the supplied compressed air.

  Thus, according to the shaft sealing device of the rotating shaft of the present embodiment, the material powder and the friction powder are reliably isolated and do not mix with each other. Therefore, even when the contamination of materials must be strictly managed, such as in the medical / fine chemical field, the quality of the product can be reliably maintained.

  Further, in the shaft seal device of the present embodiment, even if the oil seal 12 is worn and the atmosphere flows in from the outside, the flowing-in air is discharged from the exhaust system 35, so that the atmosphere of the container 1 is affected. There is no. Therefore, even when the container 1 is operated at a reduced pressure or filled with an inert gas, the wear of the oil seal 12 does not immediately affect the operating state or the quality of the product.

Further, in the shaft seal device of the present embodiment, the air seal portion including the first air seal ring 8, the first air chamber 9, the second air seal ring 10, the air seal casing 22, the air seal retainer 23, and the packing 25 is unitized. It can be easily removed from the shaft seal device. Even if powder that can become a contamination source remains in the remaining mechanism from which the air seal portion is removed, there is no fear of flowing into the container 1 during operation.
Therefore, conventionally, every time the raw material to be processed in the container 1 is changed, it is necessary to remove the shaft seal device from the rotary shaft 3 and clean the entire mechanism. However, in the shaft seal device of this embodiment, only the air seal portion is used. Just take it out and wash it. Therefore, the labor for cleaning the device is greatly reduced.

  In the shaft seal device of the rotary shaft of the present embodiment, when the container 1 is operated at atmospheric pressure, the pressure of the gas such as air supplied from the air supply system 34 is set to about 0.03 MPaG by the pressure adjustment valve 14, and the second air The pressure in the chamber 11 and the exhaust system 35 may be adjusted to about 0 to 0.01 MPaG by the throttle valve 18. In order to ensure the sealing effect, it is desirable to ensure a difference between the supply pressure and the pressure of the container 1 and the second air chamber 11 to 0.01 MPa or more.

  When the air pressure in the second air chamber 11 becomes lower than the pressure in the container 1, most of the gas such as air supplied to the first air chamber 9 flows out into the second air chamber 11, and the container 1 side There is a possibility that the air flow squirting on the surface decreases and the original sealing effect cannot be sufficiently obtained. Therefore, the gas pressure in the second air chamber 11 is preferably equal to or slightly higher than the pressure in the container 1.

  When the container 1 is operated in a reduced pressure atmosphere, for example, when the internal pressure of the container 1 is set to -0.09 MPaG, the supply gas pressure may be set to 0.02 MPaG, the exhaust pressure may be set to -0.08 MPaG, or the like. .

  In the shaft seal device of the present embodiment shown in FIG. 1, both the vacuum pipe 36 connected to the container 1 and the exhaust system 35 are connected to one vacuum pump 7. Therefore, the throttle valve 18 is inserted into the exhaust system 35 so that the pressure of the second air chamber 11 is adjusted higher than the pressure of the container 1. The vacuum pipe 36 and the exhaust system 35 are equally sucked by the vacuum pump 7, but the amount of gas sucked from the second air chamber 11 is reduced by inserting the throttle valve 18, and the pressure is lower than that of the container 1. I try not to.

  During operation, the pressure of the second air chamber 11 may be controlled by adjusting the throttle of the throttle valve 18 while comparing the pressure gauge 5 provided in the container 1 with the pressure gauge 16 provided in the exhaust system 35. The exhaust system 35 may be provided with a relief valve instead of the throttle valve 18 and the flow meter 17 may be used to perform control based on the gas flow rate.

The effect was confirmed by applying the shaft seal device of this example to an actual machine.
For a high-speed stirrer with a container capacity of 25 liters, a main shaft diameter of 60 mm, and a stirring blade speed of 100 to 500 rpm, the pressure of the pressurized air is adjusted to 0.03 MPaG, and the throttle valve provided in the exhaust system is adjusted while looking at the flow meter Then, after adjusting the air supply amount to 84 Nl / min and the air exhaust rate 17 Nl / min, charging 8 kg of the dry powder raw material into the container and carrying out a stirring test at a stirring blade speed of 300 rpm for 10 minutes, When disassembled and inspected, it was confirmed that the powder raw material did not enter the shaft seal portion.

In addition, simulated powder was attached to the vicinity of the oil seal by simulating the wear of the contact-type seal, but it was confirmed that the pseudo powder did not enter the container.
If the amount of exhaust air is small, the air seal effect is inferior, and if it is large, the amount of air consumption is increased.
The shaft seal device can be operated by adjusting the pressure.
The pressure in the container is set to 0 MPaG, the supply pressure of the pressurized air system is adjusted to 0.03 MPaG by the pressure adjustment valve, the exhaust pressure is adjusted to 0 to 0.01 MPaG by the relief valve provided in the exhaust system, and the above When the same test operation was performed, it was confirmed that the powder raw material did not enter the shaft seal portion.

In addition, when the operation is performed under reduced pressure, when the stirrer operation is performed under the conditions of the container internal pressure of -0.09 MPaG, the supply air pressure of 0.02 MPaG, and the exhaust air pressure of -0.08 MPaG, No intrusion of body ingredients could be observed.
If the difference between the supply pressure of the pressurized air and the exhaust pressure is too small, the pressurized air escapes into the container and the shaft sealing effect between the second air chamber is reduced.
Note that the optimum flow rate and pressure of the pressurized air vary depending on the type of the high-speed stirrer, the type and amount of the processing raw material, and other operating conditions, and therefore it is desirable that the pressurized air can be adjusted to meet the optimum conditions.

FIG. 4 is a sectional view of a shaft seal device of a stirrer according to another embodiment of the present invention. In the shaft seal device of the present embodiment, a metal labyrinth seal is used as an air seal. In principle, the labyrinth seal is formed so that the unevenness of the rotating portion and the unevenness of the fixed portion are engaged with each other, and a shaft seal effect is obtained by overlapping the recessed portion and the protruding portion in multiple stages.
A first labyrinth seal 40 is provided between the bottom surface of the bearing portion of the stirring blade 2 connected to the rotating shaft 3 and the first air chamber 9, and the second air chamber 9 is provided between the first air chamber 9 and the second air chamber 11. A labyrinth seal 41 is provided. Both the first labyrinth seal 40 and the second labyrinth seal 41 are opposed to the rotating body with a minute gap therebetween.
The shaft seal device of the present embodiment also exhibits the same operational effects as the shaft seal device of the embodiment shown in FIG.

  The shaft seal device of the rotary shaft according to the present invention prevents the material powder loaded in the container from entering the shaft seal portion, and prevents the friction powder and the splash of lubricating oil generated by the contact type seal from entering the container. be able to. Therefore, in various fields where contamination must be strictly managed, such as the medical field and fine chemical field, powder processing apparatuses such as a stirrer can be operated while maintaining the purity of the material.

DESCRIPTION OF SYMBOLS 1 Container 2 Stirring blade 3 Rotating shaft 4 Drive device 5 Pressure gauge 6 Bag filter 7 Vacuum pump 8 1st air seal ring 9 1st air chamber 10 2nd air seal ring 11 2nd air chamber 12 Oil seal 13 Flowmeter 14 Pressure control valve 15 Pressure gauge 16 Pressure gauge 17 Flow meter 18 Throttle valve 19 Check valve 20 Gate valve 21 Gate valve 22 Air seal casing 23 Air seal retainer 24 Oil seal casing 25 Packing 26 Lantern ring 27 Air supply hole 28 Exhaust pipe 29 Bearing casing 30 Fixing bolt 31 Bearing retainer 32 Fixing bolt 33 Bolt hole 34 Air supply system 35 Exhaust system 36 Vacuum piping 40 First labyrinth seal 41 Second labyrinth seal

Claims (5)

In a container of a powder processing apparatus that operates under reduced pressure , a first non-contact seal, a first air chamber, and a second air chamber are arranged from the inner side of the container with respect to a rotating shaft that penetrates the wall of the container. The non-contact type seal, the second air chamber, and the first contact type seal are arranged in order, and the second air chamber is operated so as to have a pressure higher than the pressure of the container . A shaft seal device for a rotating shaft, wherein the gas pressure in one air chamber is maintained higher than the gas pressure in the container and the gas pressure in the second air chamber.   The shaft sealing device for a rotary shaft according to claim 1, wherein the first air chamber is supplied with a gas via a lantern ring having a ring shape and a plurality of holes provided in an inner peripheral portion. The rotation axis of the shaft seal device according to claim 1 or 2, characterized in that it comprises a second vacuum device for depressurizing the first vacuum device and the second air chamber for depressurizing the vessel. The second provided with a throttle or the relief valve in an exhaust system connected to the air chamber from claim 1, wherein the second pressure of the air chamber, characterized in that it is adjusted to not lower than the pressure of the container 3 The shaft seal device of the rotating shaft according to any one of the above. The said 1st non-contact-type seal | sticker, the said 1st air chamber, and the said 2nd non-contact-type seal | sticker are integrally formed so that removal is possible, The any one of Claim 1 to 4 characterized by the above-mentioned. 2. A shaft seal device for a rotary shaft according to item 1.

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