3. What is Centrifugal compressor?
• It is a machine in which a gas or vapor is compressed by a radial acceleration by
an impeller
• Principle:-
A centrifugal compressor imparts kinetic energy into the airstream by
increasing the velocity of the air using a rotating element and then converts
this kinetic energy into potential energy in the form of pressure
6. Single stage
compressor
Types of Single stage compressor
- Overhung Single Stage Centrifugal Compressor
- Between bearing design single stage compressors
- Integrally geared single stage compressors
7. Overhung Single
Stage
Centrifugal
Compressor
● Located at the non-drive end of
the shaft
● These type of compressors have
axial flow suction nozzle
● Mainly designed for low
pressure, high volume application
● It can handle Gas flows up to
60,000 m³/hr and pressure ratio up
to 3.5 can be achieved
8. Between bearing
design single stage
compressors
● The impeller is mounted
between the bearings
● The impellers are semi open
type
● It can handle Gas flows up to
40,000 m³/hr, pressure ratio up to
1.45 and discharge pressure up to
2 bar can be achieved
9. Integrally
geared single
stage
compressors
● These have overhung semi open
impellers
● Impeller is overhung mounted
directly onto the high-speed shaft
of gearbox
● It can handle Gas flows up to
300,000 m³/hr, pressure ratio up to
3.5 and discharge pressure up to 50
bar can be achieved
11. Horizontally
split casing
compressor
● Cylindrical casing is divided
into two halves joined along the
center line by bolting
● It is used where the gas
operating pressure is less than
60 bars (870 psi)
● In these types the advantage
is maintenance of internal items
can be done by only removing
the upper half
12. Vertically split
casing
compressors
● Vertically split casings are formed
by a cylinder closed by two end
covers referred as barrel
● The advantage of the vertically
split joint is its high-pressure
capability due to the one-piece
construction and conventional,
proven flange type seals at each end.
● These machines which are
generally multistage are used for
high pressure services up to 680 bar
(9900 psi).
13. Compressor with
bell casing
● Used for high pressures
● These have bell shaped
casings and are closed with
shear rings instead of
bolts.
14. Pipeline
compressor
● These have bell-shaped casings with
a single vertical end cover
● They are generally used for natural
gas transportation
● They normally have side suction
and delivery nozzles positioned
opposite each other to facilitate
installation on gas pipelines
● These are generally designed for
pressure up to 100 bar (1400psi)
15. Integrally geared
multistage
compressors
● These are used either for low-flow/high
pressure, or high-flow/low pressure
conditions
● This type of compressor has a bull gear
and from one to four high speed pinions.
One or two impellers can be mounted on
each pinion-shaft
● Optimal impeller speed and the ability
to inter-cool compression stages
guarantee very high efficiency
16. Advantages
• When compared to other compressors, it is relatively agile and easy to
manufacturer.
• As this compressor does not require any special foundation it is highly energy
efficient and reliable.
• They consist of a small number of rubbing parts and are absolutely oil free in
nature.
• It generates a higher pressure ratio per stage than the axial flow compressor
17. Disadvantages
• They produce a limited amount of pressure and are not suitable for very high
compression.
• As they work at relatively high speed an enlightened or worldly mounting is
required.
• They are very sensitive towards problems such as stalling and choking
