JPH0510454A - Tandem dry gas seal - Google Patents

Abstract

PURPOSE:To prevent the intermixture of bearing oil mist into a dry gas seal by reversing the direction of the dry gas seal on the atmospheric air side, and filling seal gas from the atmospheric air side of the atmospheric air side dry gas seal. CONSTITUTION:The direction of the rotary ring 1 and static ring 2 on the atmospheric air side of a dry gas seal is made reverse to that of the rotary ring 3 and static ring 4 on the gas side. The rotary ring 1 is placed on the atmospheric air side, and dry and clean gas such as nitrogen gas is filled from the atmospheric air side. A part of filler gas passes a gap between the rotary ring 1 and the static ring 2 and is discharged from a vent 8 together with leak gas from the gas side dry gas seal, but the most of the filler gas flows into a bearing chamber 11 through an oil thrower labyrinth 9 disposed between the dry gas seal and a bearing 6. Filler gas can be filled from a chamber 10 right by the side of the atmospheric air side dry gas seal, so that the pressure of the chamber 10 can be positively made higher than that of the bearing chamber 11. The intermixture of oil mist can be thereby prevented completely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry gas seal structure and system for a non-contact dry gas seal mounted on a compressor or a blower, which completely prevents the lubricating oil for bearings from being mixed into the dry gas seal.

[0002]

2. Description of the Related Art Tandem seals are generally used in compressors that handle hazardous gases. In the tandem seal, normally only the gas side seal acts as a seal, and the atmosphere side seal acts as a backup seal only when the gas side seal causes an abnormal leak. On the other hand, the dry gas seal must be dry as an atmosphere, and when using an oil-lubricated bearing, nitrogen or air is generally used between the bearing and the dry gas seal to prevent oil mist from entering the dry gas seal side. It is sealed to prevent oil mist from entering the Trigas seal side. However, if the filled part of the filled gas cannot be sufficiently spanned with the bearing and the dry gas seal due to a structural problem, the pressure of the filled gas will not rise and the effect of the filled gas will not be effective and the oil mist will not flow to the dry gas seal side. If mixed in, the dry gas seal may be damaged. still,
The general tandem dry gas seal type is 1987
Turbomachinery maintenance congress (TURBOMACHINERYMAINTENANCE CONGRES) held in Dallas, USA
"DRY GAS SEALS FOR LOWER MAI" announced by MR.RAU.C DOREY in S)
NTENANCE AND OPERATING COSTS ”).

[0003]

The above-mentioned prior art has a problem that no consideration is given to the mixing of oil mist in the bearing. In other words, dry gas seals are generally not allowed to apply back pressure, and the most problem is that when tandem seals are used, it is not possible to inject the enclosed gas from the atmosphere side vent of the atmosphere side dry gas seal. is there.

An object of the present invention is to prevent the oil mist of the bearing from being mixed into the dry gas seal by introducing a sealed gas from the atmosphere side vent of the atmosphere side dry gas seal of the tandem seal.

[0005]

In order to achieve the above object, the atmosphere side seal of the tandem dry gas seal is reversed and both sides have a high pressure and a common vent is provided between the gas side and atmosphere side dry gas seals. It was done like this. Also,
In order to prevent the oil mist of the bearing from being mixed, the enclosed gas can be introduced directly into the dry gas seal on the atmosphere side.

[0006]

[Function] The dry gas seal consists of a rotary ring with a spiral groove cut on the high pressure side and a carbon stationary ring on the low pressure side.
This stationary ring is pressed against the rotating ring by a spring. During operation, a dynamic pressure that overcomes this spring force is generated and a high pressure gas is sealed with a slight gap. However, when back pressure is applied, this force acts to push the stationary ring against the rotating ring, so a back pressure of 0.1 Bar or more will damage the dry gas seal, and back pressure must be avoided as much as possible. I won't. Therefore, the direction of the dry gas seal on the atmosphere side is reversed, and the rotary ring with spiral grooves cut in the opposite direction to the gas side is placed on the atmosphere side, and the stationary ring is placed on the gas side. As a result, the atmosphere-side enclosed gas can be enclosed immediately from the side of the dry gas, which increases the reliability of preventing the oil mist from being mixed.

[0007]

Embodiments of the present invention will be described below with reference to FIGS. In FIG. 1, the rotary ring 1 and the stationary ring 2 on the atmosphere side of the tandem dry gas seal are oriented opposite to the rotary ring 3 and the stationary ring 4 on the gas side so that the rotary ring 1 comes to the atmospheric side. The gas side is generally higher in pressure than the atmosphere, and if the gas to be handled contains moisture or is a desired gas, the buffer gas 5 of higher pressure is introduced, and it is mainly sealed by a dry gas seal on the gas side. .. At this time, the dry gas seal on the atmosphere side serves as a backup for preventing the gas from leaking to the atmosphere when the dry gas seal on the gas side becomes abnormal. Even if a dry gas seal is used, if the bearing 6 is an oil lubricated bearing, it is necessary to prevent this oil mist from entering the dry gas seal side. Therefore, a clean gas such as nitrogen gas is filled from the atmosphere side of the atmosphere side dry gas seal with a dry gas. A part of the enclosed gas passes through the clearance between the rotary ring 1 and the stationary ring 2 of the atmosphere side dry gas seal and is released mainly from the leak gas of the gas side dry guy seal and the vent 8, but most of it is between the bearing 6. Through the oil-draining labyrinth 9 into the bearing chamber. In the conventional method, the room 10 on the atmosphere side of the atmosphere-side dry gas seal is connected to the vent line, and the enclosed gas for preventing the mixing of the oil mist can only be put from between the oil-off labyrinths 9. According to the method, since the gas can be sealed from the chamber 10 right next to the atmospheric dry gas seal, the pressure in this chamber 10 can be made higher than the pressure in the bearing chamber 11 without fail.
Therefore, it is possible to completely prevent mixing of the oil mist. Even if the gas side dry gas seal is damaged and gas pressure is applied to the atmosphere side dry gas seal, the force acts to press the stationary ring 2 against the rotary ring 1, so long as the atmosphere side dry gas seal is not damaged. Gas does not leak to the atmosphere side. In addition, if a system that detects the pressure of the vent chamber 12 of the dry gas seal and makes the pressure of the room 10 on the atmosphere side higher than that of the dry gas seal vent chamber 12 in the event of an abnormality is used, leakage to the atmosphere side will be more than that of a conventional tandem seal. High reliability can be obtained.

In FIG. 2, single dry gas seals 13 and 14 are installed in place of the tandem seal so that the atmosphere side seal 14 is opposite to the gas side seal 13, so that the same effect as the tandem seal of FIG. 1 can be obtained. You can

[0009]

According to the present invention, it is possible to completely prevent oil mist from entering the dry seal side. In addition, the vent of the dry gas seal on the atmosphere side can be used as the sealed gas introduction hole, and the number of vent lines can be reduced as compared with the conventional case. Further, in the conventional tandem seal, if the dry gas seal on the gas side was normal, it could not be detected even if the seal on the atmosphere side became abnormal, but according to the present invention, the seal on the atmosphere side as well as the gas side If an abnormality occurs and the leak increases, it can be detected in the same way as on the gas side.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a tandem seal that is an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a combination of single seals that is an embodiment of the present invention.

[Explanation of symbols]

1 ... Dry gas seal atmosphere side rotating ring, 2 ... Dry gas seal atmosphere side stationary ring, 3 ... Dry gas seal gas side rotating ring, 4 ... Dry gas seal gas side stationary ring, 7 ... Filled gas introduction hole , 9 ... Oil-drain labyrinth, 12 ... Dry gas seal vent chamber.

Claims (1)

Claim: What is claimed is: 1. A tandem dry gas, characterized in that the direction of the dry gas seal on the atmosphere side is reversed in the tandem drum gas seal, and the seal gas is sealed from the atmosphere side of the atmosphere side dry gas seal. sticker.