JP2021081021A - Shaft sealing device - Google Patents

Abstract

To provide a shaft sealing device which does not need large processing to a stationary sealing ring, and has a non-contact type mechanical seal which can exactly grasp a clearance between both sealing rings.SOLUTION: A shaft sealing device has a non-contact type mechanical seal 2 which comprises; a seal case 4 having a spring retainer 4c hung down from a machine-outside rear side end part, and a holding body 4d extending to an in-machine region side from an internal peripheral part of the spring retainer; a stationary sealing ring 18 held on the holding body 4d so as to be movable in an axial line direction; and a rotation sealing ring 19 fixed to a rotating shaft 6 while opposing the stationary sealing ring. The non-contact type mechanical seal is formed so as to relatively rotate both the sealing rings 18, 19 in a non-contact manner. An abnormality detection device 26 comprises: a measured plate 27 arranged on a base end face of the stationary sealing ring 18; a non-contact type sensor 28 arranged at the spring retainer 4c, and measuring a distance between the measured plate 27 and the spring retainer; and an alarm for issuing a warning when a detection value detected by the non-contact type sensor 28 is out of a range of a threshold T.SELECTED DRAWING: Figure 2

Description

The present invention relates to a shaft sealing device having a non-contact mechanical seal.

As shown in Patent Document 1, the non-contact type mechanical seal is in a non-contact state in which a static sealing ring held in a seal case so as to be movable in the axial direction and a rotating sealing ring fixed to a rotating shaft have a minute gap. It rotates relative to each other to seal the gas.

Therefore, in the non-contact type mechanical seal, it is necessary to constantly monitor whether or not the gap formed between the two sealing rings is an appropriate gap.

Therefore, in the conventional non-contact type mechanical seal, as described in Patent Document 1, page 2, page 13, line 3, page 4, line 4, a gas that seals whether the two sealing rings have an appropriate gap with a flow meter. A non-contact sensor provided in a statically sealed ring by forming a non-penetrating hole from the base end side of the statically sealed ring, which can be grasped by the change in amount or as disclosed in FIG. It is proposed to detect by.

Actual Kaihei 04-084868

However, the change in the amount of gas can only roughly grasp whether the gap between the two sealed rings is appropriate when a leak occurs from both sealed rings, and whether the gap between the two sealed rings is the appropriate gap. Cannot be grasped accurately. On the other hand, in the case of the non-contact type sensor, since the gap between the two sealing rings is directly detected, it is possible to accurately grasp whether or not the distance is appropriate, but the non-contact type is applied to the static sealing ring. Large processing such as making a hole to accommodate the sensor is required.

An object of the present invention is to provide a shaft sealing device having a non-contact type mechanical seal capable of accurately grasping the gap between both sealing rings without requiring a large processing on the static sealing ring.

In order to achieve this object, the present invention has a seal case having a spring retainer hanging from an end on the outer region side and a holding body extending from the inner peripheral portion thereof to the inner region side, and the holding body can be moved in the axial direction. A non-contact mechanical seal provided with a statically sealed ring held on the ground and a rotary sealing ring fixed to a rotating shaft facing the statically sealed ring so that both sealed rings are relatively rotated in a non-contact state. An abnormality detection device is provided on the spring retainer to measure the distance between the plate to be measured provided on the base end surface of the static sealing ring and the plate to be measured. We propose a shaft sealing device including a contact type sensor and an alarm device that issues an alarm when the value detected by the non-contact type sensor deviates from the threshold range.

In a preferred embodiment of the shaft sealing device, the non-contact type mechanical seal is arranged on the outer region side of the machine, and the sealing ring provided on the seal case and rotation are provided on the inner region side. A contact-type mechanical seal that rotates relative to the sealing ring provided on the shaft is provided, and purge gas is supplied to the region partitioned by both mechanical seals. Further, in such a case, the static sealing ring is composed of a sealing ring body facing the rotary sealing ring and a pressing body connected to the sealing ring body via an O-ring, and the plate to be measured is a pressing body. Provided on the base end surface, the seal case is formed with a barge gas supply path to which the purge gas is supplied toward the static sealing ring and a drain path for discharging the purge gas from the vicinity of the rotary sealing ring. Is preferable. Further, it is preferable that the plate to be measured is integrally molded with the base end surface of the static sealing ring.

In the shaft sealing device of the present invention, the distance between the plate under test provided on the base end surface of the static sealing ring and the non-contact sensor provided on the spring retainer of the seal case is measured, and this distance is within the threshold range. Since an alarm is issued when the ring is disengaged, it is possible to accurately grasp the case where the gap between the two sealing rings is not in the proper gap, and the static sealing ring does not require a large processing.

It is sectional drawing which shows an example of the shaft sealing device which concerns on this invention. It is a detailed view which shows the main part of FIG. 1 in an enlarged manner. It is sectional drawing of the partial notch which shows the modification of the shaft sealing apparatus which concerns on this invention.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

FIG. 1 is a cross section showing an example of a shaft sealing device according to the present invention, and FIG. 2 is a detailed view showing an enlarged main part of FIG.

As shown in FIG. 1, the shaft sealing device according to the present invention is installed in a rotating device such as a pump that handles liquids, and the in-flight area A and the outside area (atmospheric area) B of the rotating device are divided into an in-flight area. The end face contact type mechanical seal 1 on the side and the non-contact type mechanical seal 2 on the outer region side are configured to partition through the purge gas region C formed between the mechanical seals 1 and 2. ..

As shown in FIG. 1, the end face contact type mechanical seal 1 on the in-flight region side seals the liquid (sealed fluid) in the in-flight region A, and the seal case 4 attached to the shaft sealing portion casing 3 of the rotating device. A sealing ring (fixed sealing ring) 5 fixed to the seal case 4 and a sealing ring (movable sealing ring) held concentrically on the rotating shaft 6 of the rotating device that penetrates the seal case 4 so as to be movable in the axial direction. ) 7 and a spring 8 for pressing the movable sealing ring 7 against the fixed sealing ring 5, and the sealing ends 5a and 7a, which are the opposite end faces of the sealing rings 5 and 7, are sealed by the relative rotary sliding contact action. The in-flight region A, which is the outer peripheral side region of the end faces 5a and 7a, and the purge gas region C, which is the inner peripheral side region thereof, are partitioned.

The seal case 4 is a machine having an in-machine area side main body 4a attached to the shaft sealing portion casing 3 of the rotating device, an out-of-machine area side main body 4b attached to the in-machine area side main body 4a, and an out-of-machine area side main body 4b. A metal cylindrical structure composed of a ring plate-shaped spring retainer 4c hanging from the outer region side end and a cylindrical holder 4d integrally formed on the inner peripheral portion of the spring retainer 4c and extending in the in-flight region A direction. Is. A supply passage 9 for supplying the flushing liquid F is formed in the main body 4a on the in-flight region side, and the sealed end faces 5a of both sealing rings 5 and 7 are formed from a plurality of ejection holes 9a formed at the downstream end of the supply passage 9. , 7a, the flushing liquid F is ejected toward the entire circumference.

The fixed sealing ring 5 is configured such that its tip surface is a sealed end surface 5a which is a smooth annular plane orthogonal to the axis line, and is fixed to the base end portion of the in-machine region side main body 4a of the seal case 4. The fixed sealing ring 5 is made of carbon or the like.

A sleeve 10 having both ends 10a and 10b protruding from the seal case 4 is fitted to the rotating shaft 6. The sleeve 10 has a fixing ring 11 fitted to a base end portion 10a protruding from the seal case 4 in the direction of the outer region, and an appropriate number of first screws 12a and a sleeve 10 tightened to the rotating shaft 6 on the fixing ring 11. It is fixed to the rotating shaft 6 by screwing an appropriate number of second screws 12b tightened to. The mechanical seals 1 and 2 are rotated in the assembled state by attaching an appropriate number of connecting claws 13 engaged with the annular recess 10c formed in the sleeve 10 to the end of the seal case 4 on the outer region side. It can be attached and detached from the device.

The movable sealing ring 7 is formed by a metal sealing ring holding body 7b held on the tip 10b of the sleeve 10 via an O-ring 14 so as to be movable in the axial direction, and by shrink fitting or the like on the tip of the sealing ring holding body 7b. It is composed of a fixed sealed ring main body 7c and a metal sleeve receiver 7d connected to a base end portion of the sealed ring holder 7b so as not to rotate relative to each other. The sealing ring main body 7c is formed of a sealing end surface 7a which is a smooth annular plane whose tip surface is orthogonal to the axis, and is harder than the constituent material of the fixed sealing ring 5 (ceramics such as silicon carbide or tungsten carbide). It is composed of cemented carbide, etc.). The movable sealing ring 7 (sealing ring main body 7c) is relative to the sleeve 10 (rotating shaft 6) by engaging the drive pin 15 provided on the spring receiver 7d with the spring retainer 16 fixed to the tip portion 10b of the sleeve 10. The rotation is blocked.

The spring 8 is loaded between the spring receiver 7d of the movable sealing ring 7 and the spring retainer 16, and biases the sealing ring main body 7b of the movable sealing ring 7 against the fixed sealing ring 5.

As shown in FIG. 1, the non-contact mechanical seal 2 on the outer region side moves axially to the outer region side main body 4b of the seal case 4, the spring retainer 4c and the holding body 4d, and the holding body 4d of the seal case 4. A statically sealed ring 18 that is possibly held, a rotary sealing ring 19 that is arranged to face the statically sealed ring 18 and is fixed to the rotating shaft 6, and a spring retainer 4c of the statically sealed ring 18 and the seal case 4. A spring 20 loaded in between is provided, and the sealed end faces 18a and 19a, which are opposite end faces of both sealing rings 18 and 19, are relatively rotated while being held in a non-contact state by the dynamic pressure generated between them. This is a dynamic pressure type configured to partition the purge gas region C, which is the outer peripheral side region of the sealed end faces 18a, 19a, and the external region B, which is the inner peripheral side region thereof.

The main body 4b on the outside region side of the seal case 4 is provided with a purge gas supply path 21 for supplying the purge gas P to the purge gas region C and a drain passage 22 for discharging the purge gas P from the purge gas region C. As the purge gas P, a gas that does not hinder leakage to the outside region (atmosphere region) B and is inactive with the liquid in the inside region A is selected, and nitrogen gas is used in this example.

As shown in FIGS. 1 and 2, the static sealing ring 18 has a sealing ring main body 18b held by the holding body 4d of the sealing case 4 so as to be movable in the axial direction, and an O-ring 23 at the base end of the sealing ring main body 18b. It is composed of a metal (titanium, stainless steel, etc.) pressing body 18c connected via a press. The sealing ring main body 18b is made of carbon or the like, and the tip surface is formed of a sealing end surface 18a which is a smooth annular plane orthogonal to the axis. The sealing ring main body 18b of the static sealing ring 18 is prevented from rotating relative to the sealing case 4 by a drive pin (not shown) provided between the sealing ring main body 18b and the spring retainer 4c of the sealing case 4.

The rotary sealing ring 19 includes a metal sealing ring holder 19b fixed to the sleeve 10 via an O-ring 24 and a sealing ring main body 19c fixed to the tip of the sealing ring holder 19b via an O-ring 25. It consists of. The sealed ring body 19c is made of a ceramic such as carbon or silicon carbide, a cemented carbide such as tungsten, or the like. The tip surface of the sealing ring main body 19c is formed of a sealing end surface 19a which is a smooth annular plane orthogonal to the axis, and a dynamic pressure generating groove 19d opening in the purge gas region C is formed on the sealing end surface 19a. The dynamic pressure generating groove 19d is formed by forming a shallow groove such as a spiral shape that opens in the purge gas region C on the sealed end surface 19a of the sealing ring main body 19c.

The spring 20 is loaded between the pressing body 18c of the static sealing ring 18 and the spring retainer 4c of the sealing case 4, and the sealing ring main body 18b of the static sealing ring 18 is passed through the pressing body 18c to the rotary sealing ring 19. It is attached in the direction of the sealing ring body 19c.

By the way, in the purge gas supply path 21, the purge gas P is supplied toward the sealing ring main body 18b of the static sealing ring 18, and the supplied purge gas P is a stopper ring 4e provided on the inner peripheral portion of the outer region side main body 4b of the seal case 4. A part of the sealing end faces 18a and 19a of both sealing rings 18 and 19 flows out to the outer region B, and the other part of the rotating sealing ring 19 is guided along the outer peripheral surface of the rotating sealing ring 19. It flows out from the side to the sealed ring holder 19b and flows out from the drain path 22 with the liquid leaking from the sealed end faces 5a and 7a of the mechanical seal 1 on the in-machine region side to the purge gas region C.

According to the non-contact mechanical seal 2 on the outer region side, the purge gas P in the purge gas region C is caught between the sealed end surface 18a of the static sealing ring 18 and the sealed end surface 19a of the rotary sealing ring 19, and both sealed end surfaces 18a. Dynamic pressure is generated between the and 19a, and both sealed end faces 18a and 19a are held in a non-contact state having a minute gap (appropriate gap). A part of the purge gas P supplied from the purge gas supply path 21 to the purge gas region C is discharged to the outside region (atmospheric region) B through between the sealed end faces 18a and 19a of both sealing rings 18 and 19, and the other one. The portion is discharged from the drain path 22 with the liquid leaked from the end face contact type mechanical seal 1 on the in-machine region side.

Therefore, in the shaft sealing device according to the present invention, when the sealing function by the non-contact mechanical seal 2 on the outside region side is not functioning, the abnormality detecting device 26 detects this and issues an alarm. Is provided.

That is, as shown in FIG. 1, the abnormality detection device 26 is provided between the measured plate 27 provided on the base end surface of the static sealing ring 18 and the spring retainer 4c of the seal case 4 and between the measured plate 27. A non-contact sensor 28 that measures a distance, a controller 29 that compares the detected value of the non-contact sensor 28 with a threshold value, and an alarm device 30 that issues an alarm when the detected value of the non-contact sensor 28 deviates from the threshold value. And.

The plate 27 to be measured provided on the base end surface of the static sealing ring 18 is provided in a state orthogonal to the axis line on the base end surface of the pressing body 18c of the static sealing ring 18. In this example, since the pressing body 18c is made of a conductive metal material (titanium or the like), the plate 27 to be measured is integrally molded with the pressing body 18c, and is pressed according to the detection range of the non-contact sensor 28. It is integrally formed so that a part of the body 18c protrudes from the base end surface.

As shown in FIGS. 1 and 2, the spring retainer 4c of the seal case 4 is a non-contact type that measures the distance from the plate 27 to be measured provided on the base end surface (base end surface of the pressing body 18c) of the static sealing ring 18. A sensor 28 is provided. As the non-contact type sensor 28, for example, a non-contact type sensor that measures the distance to the plate 27 to be measured by an eddy current is used, and a male screw is formed on the outer peripheral portion thereof. The non-contact sensor 28 forms a horizontally penetrating screw hole 4f in the spring retainer 4c, and the non-contact sensor 28 is screwed into the screw hole 4f. The non-contact sensor 28 is screwed in with both ends slightly protruding from the spring retainer 4c, and a nut 31 is screwed into the base end protruding from the spring retainer 4c. The nut 31 is screwed into the non-contact sensor 28 via a sealing member 32 such as a gasket between the nut 31 and the spring retainer 4c, and seals between the non-contact sensor 28 and the spring retainer 4c. The non-contact sensor 28 is provided in the purge region C by the seal member 32 in a state of being sealed from the spring retainer 4c.

As shown in FIG. 2, the distance T between the tip of the non-contact sensor 28 and the plate 27 of the static sealing ring 18 is such that the sealing end surface 18a of the static sealing ring 18 is the sealed end surface 19a of the rotary sealing ring 19. The distance is set when the gap becomes an appropriate gap. That is, the distance is the threshold value T. Then, the controller 29 compares the value detected by the non-contact sensor 28 with the threshold value T, and when the detected value is out of the range of the threshold value T, the alarm device 30 issues an alarm (sound, light, etc.).

According to the shaft sealing device configured as described above, the liquid in the in-flight region A is sealed by the mechanical seal 1 on the in-flight region side, and when a large amount of liquid in the in-flight region A leaks into the barge region C, the liquid in the in-flight region side The non-contact type mechanical seal 2 of the above causes a leak to accompany the purge gas P and discharges the leak from the drain path 22. On the other hand, a part of the purge gas P is discharged from the purge gas region C to the outside region B.

Then, when the sealing function of the non-contact mechanical seal 2 on the outer region side becomes inappropriate for some reason and the sealing end faces 18a and 19a of both sealing rings 18 and 19 are wider or narrower than the appropriate gap. That is, when the detected value of the non-contact type sensor 28 is out of the range of the threshold value T (when it exceeds the upper limit value or falls below the lower limit value), the alarm device 30 issues an alarm. When an alarm is issued, the equipment is stopped, and the non-contact mechanical seal 2 is inspected and repaired. Immediately after the start of operation of the non-contact type mechanical seal 2, the sealed end faces 18a and 19a of both sealing rings 18 and 19 do not reach the proper gap, and the value detected by the non-contact sensor 28 is the lower limit value of the threshold value T. In this case, no alarm is issued because it is below.

At this time, since the non-contact sensor 27 is provided on the spring retainer 4c that hangs down from the end of the seal case 4 on the outside region side, the case where the sensor as disclosed in FIG. 1 of Patent Document 1 is provided. It is not necessary to perform complicated processing on the static sealing ring and the seal case portion that holds the static sealing ring, and it is necessary to process the sealing ring main body 18b of the static sealing ring 18 for the non-contact sensor 28. Absent. Therefore, the sealing ring main body 18b of the static sealing ring 18 and the holding body 4d of the sealing case 4 that holds the sealing ring body 18b do not require any processing, and the non-contact sensor 28 can be simply attached to the spring retainer 4c of the sealing case 4. Since it is only necessary to provide the screw hole 4f, the non-contact sensor 28 can be easily attached to the existing shaft sealing device. Further, since the non-contact type sensor 28 issues an alarm only when the detected value is out of the range of the threshold value T, the distance between the sealed end faces 18a and 19a of both the sealing rings 18 and 19 exceeds the appropriate distance. It is possible to accurately grasp the time point.

Further, since the pressing body 18c of the static sealing ring 18 is made of a conductive metal material (titanium or the like), the sealing main body 18b of the static sealing ring 18 is made of a material that is not superior to the conductive material such as carbon or non-conductive. It can be made of a material, and it is not necessary to make the mating sealing ring (sealing ring main body 19b of the rotary sealing ring 19) made of a conductive material as in Patent Document 1. Further, since the plate 27 to be measured is provided on the pressing body 18c which is not directly related to the function of the static sealing ring 18, the plate 27 to be measured can be integrally molded on the pressing body 18c, and one of the plates 27 to be measured. When the portion is not within the detection range of the non-contact sensor 27, a portion protruding outside the pressing body 18c can be formed. Therefore, the material of the sealing ring main body 18b of the static sealing ring 18 and the sealing ring main body 19b of the rotary sealing ring 19 can be made of the original material of the sealing ring, and the constituent materials are not limited.

Further, although the liquid leaked from the in-flight region A flows out from the drain path 22, the barge gas P accompanied by this liquid does not pass near the non-contact sensor 28. That is, the non-contact sensor 28 is sealed between the spring retainer 4c of the seal case 4 and the stopper ring 4e by the seal member 32, and only the clean purge gas P supplied from the purge gas supply path 21 invades there. Since it does not come into contact with the purge gas P accompanied by the liquid flowing out from the drain path 22, there is no possibility that the non-contact sensor 28 is contaminated or malfunctions. Therefore, the operation of the non-contact sensor 28 is always well maintained.

The configuration of the shaft sealing measure of the present invention is not limited to the above-described embodiment, and can be appropriately improved or changed without departing from the basic principle of the present invention.

For example, the end face contact type mechanical seal 1 on the in-machine region side may be composed of a movable sealing ring held in the seal case 4 so as to be movable in the axial direction and a fixed sealing ring fixed to the rotating shaft 2. Further, as the shaft sealing device, it can be applied to the case where the end face contact type mechanical seal 1 is not provided and the dynamic pressure type non-contact type mechanical seal 2 is used as a single seal. It is gas. Of course, the static sealing ring 18 may be configured as a single sealing ring, but in this case, when the single sealing ring is a material having poor conductivity such as carbon or a non-conductive material, it is covered. It is preferable that the measuring plate 27 is made of a metal material.

Further, as shown in FIG. 3, the shaft sealing device of the present invention can also be applied to the static pressure type non-contact type mechanical seal 40. That is, in the static pressure type non-contact type mechanical seal 40, the main body 42a is attached to the shaft sealing portion casing 41 of the rotating device, and the annular plate-shaped spring retainer 42b is hung down from the end of the main body 42 on the outer region side. The seal case 42, which is formed by integrally molding a cylindrical holding body 42c extending in the in-machine region A direction on the inner peripheral portion of the spring retainer 42b, and the holding body 42c of the seal case 42 can be moved in the axial direction via an O-ring 43. A statically sealed ring 44 made of held carbon or the like, and a rotary sealing ring 47 made of carbon, ceramics or the like fixed to the sleeve 46 fitted to the rotating shaft 45 of the rotating device so as to face the statically sealed ring 44. A spring (not shown) that is loaded between the base end of the static sealing ring 44 and the spring retainer 42b of the sealing case 42 and presses the static sealing ring 44 in the direction of the rotary sealing ring 47, and the main body of the sealing case 42. It includes purge gas injection paths 49, 50, and 51 that communicate the purge gas supply path 48 formed in 42a and the static pressure generating groove 44b formed in the sealed end surface 44a of the static sealing ring 44. The barge gas injection passages 49, 50, 51 are sealed by O-rings 52, 53 between the inner peripheral portion of the main body 42a of the seal case 42 and the outer peripheral portion of the static sealing ring 44, and are connected to the purge gas supply passage 48. It is composed of 49, a passage 50 formed in a static sealing ring 44 from this space 49 and connected to the static pressure generation groove 44b, and an orifice 51 interposed in the passage 50. Therefore, by supplying the barge gas P from the purge gas supply path 48 to the static pressure generation groove 44b of the static sealing ring 44, a static pressure is applied between the sealing end surface 44a of the static sealing ring 44 and the sealing end surface 47a of the rotary sealing ring 47. It is generated and the sealed end faces 44a and 47a of both sealing rings 44 and 47 are held in a non-contact state.

The static pressure type non-contact type mechanical seal 40 is provided with an abnormality detection device 54 similar to the abnormality detection device 26. That is, as shown in FIG. 3, the abnormality detection device 54 has the same non-contact sensor 28, controller 29, and alarm device 30 as described above, and a plate 55 to be measured provided on the base end surface of the static sealing ring 44. Equipped. The non-contact sensor 27 is screwed into the horizontal screw hole 4f formed in the spring retainer 42b of the seal case 42, and is fixed by the nut 31 via the seal member 32. The plate 55 to be measured is provided on the base end surface of the static sealing ring 44, but since the static sealing ring 44 is made of carbon or the like having poor conductivity, the base end surface of the static sealing ring 44 is made of metal. Is provided. Further, since the base end surface of the static sealing ring 44 is within the detection range of the non-contact sensor 27, the plate 55 to be measured has a shape that does not protrude from the base end surface of the static sealing ring 44.

Therefore, according to the abnormality detection device 54, similarly to the abnormality detection device 26, when the value detected by the non-contact sensor 27 is out of the threshold value T, that is, the sealed end faces of both the sealing rings 44 and 47. When 44a and 47a spread beyond an appropriate interval, an alarm is issued. When an alarm is issued, the equipment is stopped, and the static pressure type non-contact type mechanical seal 40 is inspected and repaired.

1 End face contact type mechanical seal 2 Non-contact type mechanical seal 4 Seal case 4c Spring retainer 4d retainer 5 Fixed sealing ring (sealing ring provided on the seal case)
6 Rotating shaft 7 Movable sealing ring (sealing ring provided on the rotating shaft)
18 Static sealed ring 18a Sealed end face 18b Sealed ring body 18c Pressing body 19 Rotating sealed ring 19a Sealed end face 21 Purge gas supply path 22 Drain path 23 O-ring 26 Abnormality detection device 27 Measured plate 28 Non-contact sensor 30 Alarm 40 Non-contact Mechanical seal 42 Seal case 42b Spring retainer 42c Holder 44 Static sealing ring 44 Sealed end face 45 Rotating shaft 47 Rotating sealing ring 47a Sealed end face 54 Abnormality detection device 55 Measured plate A Inside area B Outside area (atmospheric area)
C Purge gas area P Purge gas T Threshold

Claims (4)

A seal case having a spring retainer hanging from an end on the outer region side and a holding body extending from the inner peripheral portion thereof to the inner region side, a static sealing ring held by the holding body so as to be movable in the axial direction, and static sealing A shaft sealing device having a rotary sealing ring fixed to a rotating shaft facing the ring and having a non-contact mechanical seal that allows both sealing rings to rotate relative to each other in a non-contact state.
An abnormality detection device includes a non-contact sensor provided on the base end surface of the static sealing ring and a non-contact sensor provided on the spring retainer to measure the distance between the plate to be measured, and the non-contact type. A shaft sealing device including an alarm that issues an alarm when a value detected by a sensor deviates from the threshold range. The non-contact type mechanical seal is arranged on the outer region side of the machine, and the sealing ring provided on the seal case and the sealing ring provided on the rotating shaft rotate relative to each other on the inner region side in a contact state. The shaft sealing device according to claim 1, wherein an end face contact type mechanical seal is provided, and purge gas is supplied to a region partitioned by both mechanical seals. The static sealing ring is composed of a sealing ring body facing the rotary sealing ring and a pressing body connected to the sealing ring body via an O-ring, and the plate to be measured is provided on the base end surface of the pressing body. The seal case is characterized in that a barge gas supply path for supplying the purge gas toward the static sealing ring and a drain path for discharging the purge gas from the vicinity of the rotary sealing ring are formed. , The shaft sealing device according to claim 2. The shaft sealing device according to any one of claims 1 to 3, wherein the plate to be measured is integrally molded with a base end surface of the static sealing ring.

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