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TurboMachines Intro and Compressors Types 1

Turbomachine is a device in which energy
exchange is accomplished by hydrodynamic
forces arising between the moving fluid and
the rotating and stationary elements of the
- Daily
Turbomachine is a device in which energy is
transferred either to, or from a continuously
flowing fluid by dynamic action of one or
more moving bladed rows
A Turbomachine is characterised by dynamic
action of one or several rotating elements and
rapidly moving fluid
Turbomachine is a device in which
energy transfer occurs between a
continuously flowing fluid and a
rotating element due to
dynamic action and results in a
change in pressure or momentum
of fluid.
Turbomachines -Three Types
Power Generating
Gas, Hydro, Steam, Wind
Power Absorbing
Fans, Blowers, Compressors
Power Transmitting
Hydraulic coupling
Torque converter
A typical Compressor System
(CM4120 Julie King)
Sectional View
Compressors used to increase the pressure
of a gas (compressible fluid)
 Examples
– Increase the pressure for instrument air
systems (to get control valves to operate),
transport gases such as hydrogen,
nitrogen, fuel gas, etc. in a chemical plant
2 CLASSES of Compressors
Positive Displacement : Operate by trapping a
specific volume of gas and forcing it into a smaller
– 2 Basic Designs
» Rotary
» Reciprocating
Non positive Displacement /ROTODYNAMIC :
Operate by accelerating the gas and converting the
energy to pressure (THESE ARE TURBO MACHINES ! )
– 2 Basic Designs
» Centrifugal
» Axial
(Positive Displacement type)
Positive Displacement (PD)
Compressors: Rotary Design
Rotary compressors (get their name from the
rotating motion of the transfer element)
compress gases with lobes, screws, and vanes
into smaller volumes.
 4 Primary Types of PD Rotary Compressors:
– Rotary Screw
– Sliding Vane
– Lobe
– Liquid Ring
Rotary Screw Compressor
Rotary Screw Compressors
Commonly used in industry.
It operates with 2 helical rotors that rotate toward each
other, causing the teeth to mesh.
As the left rotor turns clockwise, the right rotor rotates
counterclockwise. This forces the gases to become
trapped in the central cavity.
The 2 rotors are attached to a drive shaft and drive that
provide energy to operate the compressor.
Have an inlet suction line and outlet discharge port.
Sliding Vane Compressor
Sliding Vane Compressors
Uses a slightly off-center rotor with sliding vanes
to compress gas.
Inlet gas flows into the vanes when they are fully
extended and form the largest pocket. As the vanes
turn toward the discharge port, the gases are
As the volume decreases, the pressure increases
until maximum compression is achieved. Then the
gas is discharged out of the compressor.
Lobe Compressor
Lobe Compressors
Characterized by 2 bean shaped impellers used
to trap and transfer gases.
The 2 impellers move in opposite directions on
parallel mounted shafts as the lobes sweep
across the suction port.
Compressed gases are released into the
discharge line.
The lobes do not touch each other. Very small
clearance(of the order of a fraction of mm.)
exists between the casing and lobes.
Lobe Compressors
Designed to have constant volume
discharge pressures and constant speed
 Lobe Compressors can be used as
compressors or vacuum pumps.
Liquid Ring Compressors
It has one moving transfer element and a casing
that is filled with water or seal liquid.
As the rotor turns, the fluid is centrifugally forced
to the outer wall of the elliptical casing. An air
pocket is formed in the center of the casing.
As the liquid ring compressor rotates, a small % of
the liquid escapes out through discharge port. Make
up water or seal liquid is added to the compressor
during operation. The liquid helps cool the
compressed gases.
Liquid Ring Compressors
Used to compress hazardous and toxic gases as
well as hot gases.
Liquid Ring Compressor
The rotor is positioned centrally in an oval-shaped
body. Upon rotation, which proceeds without metal to
metal contact, a ring of liquid is formed which moves
with the rotor and follows the shape of the body.
At the two points of the nearest proximity of the
rotational axis and body, this completely fills the
chambers of the rotor and as rotation proceeds, it
follows the contour of the body and recedes again,
leaving spaces to be filled by the incoming gas.These
spaces are connected via the cone porting to the inlet of
the compressor.
Liquid Ring Compressor
As a result of the suction action thus created, gas is
pulled into the compressor.
As the rotation progresses, the liquid is forced back
into the chambers, This gas is forced out of the
discharge port and then leaves the compressor via the
outlet flange.
The compressor is fed continuously with liquid which
serves the clearances between inlet and discharge port
and remove the heat of compression. This liquid
together with the gas to be compressed and is
separated from the discharge separator.
Positive Displacement Reciprocating
Most common type of compressors.
 Work by trapping and compressing specific
volumes of gas between a piston and a
cylinder wall.
 The back and forth motion incorporated by a
reciprocating compressor pulls gas in on the
suction (or intake) stroke and discharges it
on the other.
 Spring-loaded suction and discharge valves
open/close automatically as the piston moves
up and down in the cylinder chamber.
Positive Displacement Reciprocating
Basic Parts of are:
Connecting Rod
Piston Rings
Suction Line
Discharge Line
Spring -Loaded Suction and Discharge Valves
Positive Displacement:Reciprocating
Can have 1 to 4 cylinders. One shown only has
one cylinder.
Multi Stage Reciprocating
Discharge from Stage 1 is suction for Stage 2.
( Non-Positive Displacement type)
Rotodynamic Compressors
Centrifugal Compressor
Centrifugal Compressor
Centrifugal Compressor
Centrifugal Compressor
Centrifugal compressors accelerates the
velocity of the gases (increases kinetic
energy) which is then converted into
pressure as the gas flow leaves the volute
and enters the discharge pipe.
 Usually operate at speeds > 3,000 rpm.
 Deliver much higher flow rates than
positive displacement compressors.
Centrifugal Compressor
2 Types of Centrifugal Compressors
– Single- Stage : Compress the gas once
» Use for high gas flow rates, low discharge
– Multi- Stage : Take the discharge of one
stage and pass it to the suction of another
» Use for high gas flow rates, high discharge
Centrifugal Compressor
Basic Components
– Impellers, Vanes, Volutes, Suction Eyes,
Discharge lines, Diffuser Plates, Seals,
Shaft, Casing
– Suction Vane Tips = Part of the impeller
vane that comes into contact with gas first.
– Discharge Vane Tips = Part of the impeller
vane that comes into contact with gas last
Axial Compressor
Axial Compressor
Axial Compressor
Axial Compressor
Axial Compressor
Composed of a rotor that has rows of fan like
In industry, axial compressors are used a lot
where high flow rates and pressures are
Gas flows along the shaft, axially.
Rotating blades attached to a shaft push gases
over stationary blades called stators.
Stator blades are attached to the casing.
Axial Compressor……...
 As
the gas velocity is increased by the
rotating blades, the stator blades slow
it down. As the gas slows down,
kinetic energy is converted into
pressure. ( Diffuser action)
 Gas
velocity increases as it moves
from stage to stage until it reaches the
Axial Compressor……...
 Multi-Stage
axial compressors can
generate very high flow rates and
discharge pressures.
 Axial compressors are usually limited
to 16 stages (due to
temperature/material limitations)
 Axial compressors are lighter, more
efficient, and smaller than centrifugal