Overview of floating ring seals and common advantages and disadvantages

The floating ring seal is referred to as a floating ring seal and is used for shaft seals such as centrifugal compressors, hydrogen cooled gas turbine generators, and centrifugal pumps.
Available in medium and high pressure centrifugal compressors are: mechanical seals, labyrinth seals and packing seals. However, since the heat dissipation and lubrication conditions of the gas are not as good as the liquid, the packing seal is only used for small and low speed, and the mechanical seal is difficult to adapt after the peripheral speed is higher than 40 m/s and the temperature is higher than 200 °C. Only the labyrinth seal and the floating ring seal are The two most common ways.

Floating ring seals have the following advantages:

1) The sealing structure is simple, and there are only a few simple rings, pins, springs and other parts. Multi-layer floating rings also have only a combination of these simple parts, less than mechanically sealed parts.

2) It is not sensitive to the running state of the machine and has stable sealing performance.

3) The seals are not worn, the seal is reliable, the maintenance is simple, and the maintenance is convenient.

4) Because the seal material is metal, it is solid and resistant to high temperatures.

5) The floating ring can be used in parallel to form a multi-layer floating ring, which can effectively seal the high pressure of 10 MPa or more.

6) It can be used for high-speed rotary fluid machines of 10000～20000r/min, especially for gas compressors, and its allowable speed is up to 100m/s, which is unmatched by other seals.

7) As long as the corrosion-resistant metal material or the non-metallic material (such as graphite) which is lining corrosion-resistant is used as the floating ring, it can be used for the sealing of strong corrosive medium.

8) Because the liquid gap is in the seal gap, the friction power is extremely small, so that the machine has higher efficiency.

Disadvantages of the floating ring seal: the manufacturing precision of the seal is high, and the different degrees of the ring and the non-perpendicularity of the end face and the surface roughness have a significant influence on the sealing performance. In addition, this seal does not seal the liquid. Although the gas can be sealed, it requires a complicated and expensive automatic oil supply system.
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