Brochure

16 GE Centrifugal & Axial Compressors
Seals
Shaft end seals eliminate or minimize the
leakage of compressed gas or the entry of air
into the compressor casing. Depending on the
nature of the gas to be compressed and on
the degree of sealing to be achieved, different
types of seals may be used.
Labyrinth seals
They are used when the properties and
pressure of a gas permit a minimal leakage.
The labyrinths are made of light alloy or other
corrosion-resistant material and are easily
replaceable. The number of teeth and
clearance depend on the operating
conditions, as well as the geometry (plain,
step, ring type, honey-comb, etc.). To minimize
leakage, abradable seals are used. In this
case the labyrinth teeth are fitted to the rotor
and are in contact with an abradable material
on the stator.
When no leakage whatsoever is permissible
(poisonous or explosive gases, etc.) labyrinth
seals are combined with extraction and/or
injection systems.
Dry gas seals
Sealing is ensured by a gas lock created by
the grooves machined into a rotating seal
fitted on the rotor. Depending on the
application it is possible to use gas - taken off
the compressor at different levels: first
impeller diffuser, intermediate or discharge
nozzles or an insert gas.
Hydrostatic and hydrodynamic forces balance
to maintain a clearance of a few microns
between the rotating seals and the stationary
face. This very small clearance reduces gas
leakage to a negligible amount.
Different patented solutions are available to
temper the seals to prevent liquid or hydrate
formation or for controlling the temperature of
the seal.
Extensive experience has been accumulated on
dry gas seal systems that have been developed
to meet specific process requirements.
Oil seals and mechanical seals are available at
request, tend to be replaced by Dry Gas Seals.
Compressor Components