JP2002022018A - Shaft seal device by gland packing of rotation shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To considerably prevent a fine powder particle from entering a seal surface, reduce abrasion of an inner peripheral surface of a gland packing, reduce tightening frequency of the gland packing, and improve durability of a shaft seal device. SOLUTION: In a shaft seal device by a gland packing G with respect to a high pressure gas in which the fine powder particle is mixed, a dust seal 2 by a lip seal, a labyrinth seal R, a fluid seal F by a seal gas, and the gland packing G to which a grease lubrication is applied are arranged in this order from an inside of a high pressure container. While an outer seal 19 is arranged in a gland pushing end of the gland packing, and the seal gas introduced from an outside is discharged inside the container through the fluid seal F, the labyrinth seal R, and the dust seal 2, an appropriate amount of the seal gas is discharged from a space of the fluid seal to the outside, and before being contact with the gland packing, the entering powder particle is surely and positively discharged to the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft sealing device using a gland packing of a mechanical device having a rotating shaft installed in a high-temperature and high-pressure gas containing fine particles. The purpose of the present invention is to suppress the wear of the gland packing and the deterioration of the sealing function caused by the abrasion, thereby remarkably improving the durability of the shaft sealing device using the gland packing.

[0002]

2. Description of the Related Art A mechanical device in which a rotating shaft penetrating an end wall of a high-temperature, high-pressure (for example, 1 kg / 1 cm ² or more) gas container containing fine particles is sealed with a shaft sealing device using gland packing is known. There are various things. Particularly in a pressurized fluidized bed boiler (hereinafter referred to as PFBC), ash particles are contained in a high-temperature and high-pressure combustion gas in a range from submicron to several mm, and are collected by furnace bottom ash or cyclones extracted from the PFBC body. The fly ash to be discharged is also discharged by a mechanical device having a rotating shaft. As a shaft sealing device, a combination of a gland packing as shown in FIG. 2 and a fluid seal using an inert gas is generally used. Used in The shaft seal device shown in FIG. 2 is an example of a screw feeder shaft seal device installed for cooling and conveying furnace bottom ash and fly ash of PFBC. A screw feeder shaft 21 penetrates the end wall 20 of the screw feeder,
From the inner side, a gland packing 22, a lantern ring 23 for introducing a seal gas, and a gland packing 24 are arranged in this order. The inert gas (air or N ₂ gas, etc.) introduced from the lantern ring is adjusted at a pressure slightly higher than the internal pressure of the screw feeder, so as to reliably purge the fine ash that tends to enter the gland packing side from inside the screw feeder. Is what you do. In the conventional shaft sealing device described above, the ash that has invaded the gland packing by the inert gas is to be purged. However, the gap between the rotation shaft and the gland packing is not uniform due to the holding or runout of the rotation shaft. In addition, it is inevitable that the flow rate of the purge gas becomes unbalanced and fine ash enters the gland packing to some extent and comes into contact with the inner surface of the gland packing. Coal ash is highly abrasive and, once in contact with the gland packing, will severely damage the gland packing, resulting in a remarkable increase in the amount of seal gas and frequent retightening of the gland packing.
In addition, as a result, frequent replacement of the gland packing is required, which increases maintenance costs. The above problem qualitatively occurs regardless of the degree of abrasion (polishing action) of the fine granular material, but in the case of coal ash,
This is a particularly serious problem as it is extremely significant.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a shaft sealing device using a gland packing for a high-pressure gas mixed with a fine particle to prevent the fine particles from entering the inner surface of the gland reliably. It is assumed that.

[0004]

Means taken to solve the problem The means adopted for the above solution is based on the premise that a shaft sealing device using a gland packing for high-pressure gas mixed with fine particles is used as follows.
(D). (A) A dust seal, a labyrinth seal, a fluid seal portion having a seal gas inlet and an exhaust port, and a gland packing are arranged in order from the inside of the high-pressure vessel. (Port) A seal gas inlet and an exhaust port are provided. (C) A grease reservoir was provided in the middle of the gland packing, and (d) an external seal was provided in the gland presser.

[0005]

[Action] flow rate regulated sealed gas regulating valve or an orifice or the like (air or an inert gas such as N ₂ gas) is passed through the labyrinth seal, the dust seal is released into the container. Since the dust seal is made of an elastic material such as rubber according to the pressure and temperature conditions, the gap between the rotating shaft and the dust seal is always kept to a minimum, and a small amount of the seal gas is required to secure a seal gas velocity that can be purged. Will be. The labyrinth seal is made as small as possible, regardless of whether it is made of metal or non-metal, so that the gap with the rotating shaft is reduced as much as possible, the seal gas is made uniform in the circumferential direction, and the dust seal is damaged by any chance. Also acts as a backup in case. When the rotation axis is inclined, etc., it is not possible to completely prevent the intrusion of the fine particles by itself, and the fine particles that have entered through the exhaust port provided in the fluid seal portion are forcibly discharged. . The amount of exhaust is calculated from the relationship between the amount of seal gas flowing in and the required amount of purge into the pressure vessel, and is adjusted by a control valve, an orifice, or the like. Also, in order to effectively discharge the fine particles that have entered, the exhaust port is provided on the inner side than the inlet of the seal gas so that the seal gas flows in the direction opposite to the direction in which the fine particles enter. . As described above, the fine particles that have entered will be discharged without contacting the gland packing, but in order to ensure safety and reliability, make sure that the sealing gas does not escape from the gland packing to the atmosphere. is necessary. For this purpose, the gland packing is forcibly lubricated with grease to improve the sealing performance on the inner surface of the gland packing and extend the life of the gland packing. In addition, by installing an external seal such as a seal made of an elastic material such as rubber or a mechanical seal made of graphite etc. in the gland holding part, the seal gas escapes to the atmosphere by minimizing the difference between the inside and outside pressure applied to the gland packing. Can be minimized.

[0006]

Next, an example in which the present invention is applied to a shaft sealing device for a rotary shaft of a screw feeder provided below a cyclone of a pressurized fluidized-bed boiler will be described with reference to FIG. A dust seal 2 with a lip made of heat-resistant rubber (for example, a fluorine resin) suitable for the ambient temperature is installed on the innermost side of the wall of the container 20 to block most of the high-temperature powder. If there is a possibility that the temperature of the high-temperature granular material may exceed the allowable temperature of the sealing material, the surroundings may be provided with a water-cooled structure, or a flame-retardant sheet packing may be provided in front of the sealing material. Next to the dust seal, a plurality of plate rings 3 made of metal or non-metal (for example, a plate gasket or the like) are provided to provide a labyrinth effect so that fine powder passing through the dust seal can be effectively purged with a small amount of seal gas. I do. Tighten the dust seal and labyrinth seal with a bolt
Tighten with. Two annular grooves are provided adjacently on the inner peripheral surface at the container-side end of the cylindrical body 4, and a supply hole 10 for an inert gas (for example, N ₂ gas) communicates with the outer annular groove 7. An inert gas discharge hole 11 communicates with the annular groove 8 on the side. An orifice (or a control valve) is provided in the inert gas supply pipe so that the flow velocity is optimal for purging fine powder that is going to enter from the dust seal section and the labyrinth seal section. The exhaust pipe is provided with an orifice that discharges about 10 to 30% of the supply amount of the inert gas so that the powder passing through the labyrinth can be reliably discharged to the outside of the system, and the aging of the labyrinth and the like can be prevented. High temperature gas inside the container is not released even in case of damage. The other end of the cylindrical body 4 has a stuffing box shape, and ground packing rings 12 and 13 are provided (two or more of the same type or different types) to form a ground packing loop A. A spacer ring 14 having an H-shaped cross section is interposed outside the ground packing loop A, and the space of the spacer ring is filled with grease. A grease injection hole is provided in the cylindrical body so that grease can be supplied to the spacer ring from the outside. Gland packing rings 12 and 13 are provided outside the spacer ring (three or more of the same type or different types) to form a gland packing loop B. The gland packing retainer 17 is pressed by a spring so as to always apply an appropriate tightening surface pressure to the gland packing loops A and B. An outer seal 19 made of heat-resistant rubber is provided at an end of the gland packing retainer 17 to prevent grease from flowing out and minimize a differential pressure applied to the gland packing. In FIG. 1, the left side of the end wall 20 is the inside of the screw feeder, and the rotation axis of the screw feeder is inclined by 15 degrees. N injected from the supply hole 10
_{The two} gases form an N ₂ gas curtain in the process from the annular groove 7 to the annular groove 8 so as to effectively purge the powder that has entered. In the annular groove 8, the N ₂ gas is branched for the purge gas on the labyrinth seal side and for the exhaust gas to the exhaust hole 11 side for discharging the intruding powder out of the system. N ₂ gas for the purge gas passes through the multi-stage labyrinth seal R,
Further, the air is blown into the screw feeder through a dust seal having a lip seal structure. In this embodiment, the gas passing speed in the labyrinth portion and the dust seal portion is set to 3 m / sec or more, and the sedimentation speed for the maximum possible particle diameter of the intruding powder is secured. Also, the supply pipe 16
Because the grease filled is filled in the grease reservoir 15 from gland packing group A, the sliding surface of the rotary shaft of B are lubricated with oil film, prevents the escape to the atmosphere side of the N ₂ gas The wear of the gland packing is suppressed. When the gland packing wears and the outflow of N ₂ gas to the atmosphere increases, the invading powder tends to enter the gap between the gland packing and the rotating shaft, and the gland packing is abraded at an accelerated rate. In order to prevent this, in this embodiment, the end of the gland packing retainer is N
₍₂₎ A U-shaped seal made of heat-resistant rubber is provided to minimize outflow of gas.

[0007]

As described above, according to the present invention, the purging action by the seal gas in the lip-shaped dust seal or labyrinth seal portion, the air curtain action by the purge gas in the intermediate portion, and the forcibly entering the fine powder out of the system. The discharged powder excluding action prevents the fine powder from entering the gland packing, thereby preventing abrasion damage caused by the invading powder of the gland packing. In addition, by providing a grease reservoir between the gland packing loops and further providing an external seal at the gland packing holding end, the above-described effect is surely further improved, and the durability of the shaft sealing device by the gland packing is greatly improved. be able to.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a shaft sealing device for a rotating shaft using a gland packing according to an embodiment.

FIG. 2 is a sectional view of a conventional shaft sealing device for a rotating shaft using a gland packing.

FIG. 3 is a front view of a coal ash transport screw feeder attached to a cyclone of a coal-fired boiler to which the present invention is applied.

[Explanation of symbols]

2: Lip sealing ring (dust) 3: Labyrinth rings 4: cylinder 10: _{N 2} gas inlet holes 10 12 and 13: gland packing ring 14: the spacer ring 15: grease reservoir 17: Ground 19: outer seal 20: container End wall 21: Rotating shaft E: Escape port F: Fluid seal G: Gland packing R: Labyrinth seal S: Sleeve

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kazuyoshi Ochi 2-1-1, Minamisuna, Koto-ku, Tokyo Inside Kawasaki Heavy Industries, Ltd. Tokyo Design Office (72) Inventor Tokuaki Ishikawa 2--11, Minamisuna, Koto-ku, Tokyo No. 1 Kawasaki Heavy Industries, Ltd. Tokyo Design Office F-term (reference) 3J042 AA04 AA12 BA03 CA10 DA09 3J043 AA16 DA09 HA01 HA03 HA04

Claims (5)

[Claims] 1. A shaft sealing device for a rotating shaft by a gland packing against a high-pressure gas mixed with fine particles, wherein a dust seal, a labyrinth seal,
A fluid seal portion and a gland packing are arranged in order, and the labyrinth seal and the dust seal are passed with the seal gas flowing into the fluid seal portion to purge fine particles that are about to enter, and to the fluid seal portion. A shaft sealing device for a rotating shaft that positively discharges fine particles that have entered through an exhaust port provided. 2. The shaft seal according to claim 1, wherein the position of the seal gas inlet and the seal gas outlet is shifted in the axial direction, and the fine particles entering the space are exhausted by the counterflow seal gas. apparatus. 3. The method according to claim 1, wherein the flow rate of the sealing gas is adjusted and the flow rate of the sealing gas is adjusted so that the amount of the sealing gas is suppressed, the amount of the gas purged into the high-pressure vessel is ensured, and the fine particles that have entered are reliably exhausted. The shaft sealing device according to claim 1. 4. The shaft sealing device according to claim 1, wherein grease is forcibly lubricated on the sliding surface for improving the sealing property of the gland packing and extending the life. 5. An external seal is provided outside the gland packing to prevent the gas inside the high-pressure vessel from flowing out to the outside air.
5. The shaft sealing device according to claim 1, wherein dust is prevented from entering the gland packing.