JPS6238056Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a shaft sealing device used for a rotating shaft of a turbo compressor or the like.

Conventionally, in this type of shaft sealing device, as shown in FIG. Shaft sealing liquid is supplied from a supply source to the shaft sealing liquid supply chamber 4 through a supply path 10 . An overhead tank 2 is provided in communication with the supply path 10, and a gas phase portion of the overhead tank 2 and an equal pressure gas chamber 3 are communicated through a reference gas line 5. 6 is a control valve that adjusts the liquid level of the shaft sealing liquid in the overhead tank 2; 7 is a control valve that detects the liquid level of the shaft sealing liquid in the overhead tank 2, and detects the level between the level target value. The level controller is a level control mechanism that outputs a level signal to operate the control valve 6 according to the amount of deviation, and is used to maintain the liquid level at a predetermined level. The internal pressure is set to a predetermined differential pressure (for example, 0.35 to 0.6 kg) than the internal pressure of the equalizing gas chamber 3.
In order to maintain this differential pressure as high as ¹ /cm2), this pressure difference is provided by a predetermined water head corresponding to the liquid level in the overhead tank 2.

However, in such conventional systems, the gas pressure within the pressure equalizing gas chamber 3 changes rapidly during transient conditions such as when the compressor 1 is started, when the load changes, or when the compressor 1 is stopped. tank 2
Since there is a gas section with a certain volume in the upper part of the tank, there is a time delay before the gas pressure pressing down on the shaft sealing liquid level in the overhead tank 2 reaches the gas pressure in the pressure equalizing gas chamber 3. It may not be possible to maintain a sufficient differential pressure, and compressed gas may leak to the outside.

The present invention eliminates the above-mentioned drawbacks of the conventional devices and provides a shaft sealing device that always maintains the necessary differential pressure and prevents gas leakage even if the pressure in the pressure-equalizing gas chamber suddenly changes in a transient state. This is the purpose.

The present invention provides a shaft sealing section including a pressure equalizing gas chamber and a shaft sealing liquid supply chamber provided in a shaft penetrating portion of a rotating shaft, and a shaft sealing section that communicates with the shaft sealing liquid supply chamber and the pressure equalizing gas chamber. an overhead tank that applies pressure; a supply path that supplies shaft sealing liquid to the overhead tank and the shaft sealing liquid supply chamber; and a control valve provided in the supply path that adjusts the liquid level in the overhead tank. a level control mechanism that detects the liquid level and operates the control valve according to a level deviation amount between the liquid level and the level target value; an internal pressure of the pressure equalizing gas chamber; Detecting the differential pressure between the internal pressure of the shaft sealing liquid supply chamber, emitting a differential pressure signal according to the amount of differential pressure deviation between the detected differential pressure and the differential pressure target value, and controlling the differential pressure signal to the level. a differential pressure control mechanism for controlling the differential pressure; and changing the target level value according to the differential pressure signal when the deviation amount of the differential pressure from the target differential pressure value exceeds a predetermined allowable limit. This is a shaft sealing device characterized in that the shaft sealing device is configured to be set as follows.

Embodiments of the present invention will be described using the drawings.

In FIG. 2, 8 is a differential pressure controller as a differential pressure control mechanism, which detects the differential pressure between the internal pressure of the pressure equalizing gas chamber 3 and the pressure of the supply path 10, and uses this detected differential pressure,
A differential pressure signal corresponding to a differential pressure deviation amount from a predetermined target differential pressure value is generated.

This differential pressure signal is sent to the level controller 7 to set a level target value. That is, the level target value of the level controller 7 is changed and set according to the differential pressure detected by the differential pressure controller 8.

For the differential pressure target value, positive and negative tolerance limits are determined as deviation amounts, and a differential pressure signal is issued when the deviation amount of the detected differential pressure exceeds the tolerance limits. The positive limit is to prevent the shaft sealing liquid from flowing into the pressure equalizing gas chamber 3 due to too large a pressure difference.

A limiter 9 regulates the upper and lower limits of the target level value setting range.

During normal operation, the deviation amount of the differential pressure is within the permissible limit, so no differential pressure signal is output, and level control is performed with respect to the level target value set to the normal value. When the differential pressure exceeds the allowable limit, a differential pressure signal is generated, and the level target value is set to change in response to the actual differential pressure, creating a deviation from the liquid level, and the control valve is adjusted based on this deviation amount. 6 is operated to control the water level, and the pressure in the shaft sealing liquid supply chamber 4 is increased to compensate for the lack of pressure due to a delay in the pressure of the gas phase portion of the overhead tank 2 with the water head due to the rise in the water level, thereby increasing the pressure in the shaft sealing liquid supply chamber 4 to a predetermined difference. It's starting to gain pressure.

With this invention, the shaft sealing liquid pressure is always kept higher than the equalized gas chamber pressure by a predetermined differential pressure even in transient conditions such as when the compressor starts, stops, or when the load suddenly changes, thereby preventing gas leakage. It is possible to provide a shaft sealing device that is free from fear, and it is possible to achieve extremely great effects in terms of practical safety.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram of a conventional example, and FIG. 2 is a flow diagram of an embodiment of the present invention. 1...Compressor, 2...Overhead tank,
3... Equal pressure gas chamber, 4... Shaft sealing liquid supply chamber, 5...
Reference gas line, 6... Control valve, 7...
Level controller, 8... Differential pressure controller, 9... Limiter, 10... Supply path.

Claims (1)

[Scope of utility model registration request] A shaft sealing section consisting of a pressure equalizing gas chamber and a shaft sealing liquid supply chamber provided in a shaft penetrating portion of the rotating shaft, and an overpass that communicates with the shaft sealing liquid supply chamber and the pressure equalizing gas chamber to provide a differential pressure. A head tank, a supply path for supplying shaft sealing liquid to the overhead tank and the shaft sealing liquid supply chamber, and a control valve provided in the supply path to adjust the liquid level in the overhead tank. In the shaft sealing device; a level control mechanism that detects the liquid level and operates the control valve according to a level deviation amount from the level target value; an internal pressure of the pressure equalizing gas chamber and the shaft sealing liquid supply; A differential pressure sensor that detects a differential pressure with the internal pressure of a room, generates a differential pressure signal according to the amount of differential pressure deviation between the detected differential pressure and a differential pressure target value, and supplies the differential pressure signal to the level control mechanism. A pressure control mechanism;
When the deviation amount of the differential pressure from the target differential pressure value exceeds a predetermined tolerance limit, depending on the differential pressure signal,
A shaft sealing device characterized in that the level target value is changed and set.