Basic Theory of Compress Air Plant Engineering

3/13/2020
phorose174@gmail.com 1
DJJ6182 : ENGINEERING PLANT
TECHNOLOGY
Prepared by;
Petrus Banati @ Fazzerius,
M. Mfg. Eng. (Mfg. Sys. Eng.), UTeM
B. Mech. Eng. (Plant), (Hons), UTHM
Dip. Edu. (Mech. Eng.) , IPTKL
Dip. Mech. Eng. (Automotive), PKB
Grad. IEM
Mechanical Engineering Department,
Polytechnic of Kota Kinabalu, Sabah
Dis 2019
COMPRESSED AIR PLANT (05 : 00)
• This topic introduces on the arrangement,
tools and usage of compressed air plant. This
topic explains on the advantages of using
compressed air as task agent by providing
examples of usage.

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 Compressed Air => air kept under a
pressure greater than atmospheric
pressure.
 Serve many domestic and industrial
purpose.
 Use in Pneumatic System.

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• To gather and compress air from normal to high pressure. Those air
compressors in which successive volumes of air are enclosed and then
elevated to a higher pressure by reducing the volume of the enclosure
holding air
COMPRESSOR
• To receive and keep compressed air. Receiver should be fitted with a
safety valve, pressure gauge to manage the air pressure
AIR TANK
• To dry the compressed air before it is provided to pneumatic system and
to avoid pneumatic components from corrosion
AIR DRYER
• Normally consist of three components. There are filter, regulator and
lubricator. Its functions is to remove all contaminants such as dust and
rust particles from the compressed air, manage air pressure and to
extend the life of pneumatic system components which need lubrication
SERVICE UNIT
• Determines the flow of air between its ports by opening, closing or
changing its internal connections. So, directional valve is used to control
air and cylinder direction or movement.
DIRECTIONAL VALVE
• To transform the potential energy of the compressed air into mechanical
work. The work done by pneumatic actuator can be linear or rotary.
ACTUATOR
Pneumatic System
For continuing performance of control systems and working elements it is
necessary
to guarantee that the air supply is:
The equipment to be considered in the generation and preparation of air
include:
At the required pressure Dry Clean
Inlet filter
Air compressor
Air reservoir
Air dryer
Air filter with water separator
Pressure regulator
Air lubricator as require
Drainage point

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ms4.18 Basic Pneumatic System/Tieh SF 7
Air Compressor
 It takes in atmospheric
air.
 Compresses the air so
as to increase the air
pressure.
 Transfers the
compressed air into an
air receiver.
 Intake Air Filter
◦ Prevent dust from entering compressor
 Inter-stage Coolers
◦ Reduce the temperature of the air before enter the
next stage.
 After Coolers
◦ To remove the moisture in the air by reducing the
temperature in water-cooled heat exchanger.

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 Air-dryers
◦ Removes the remaining traces of moisture after
after-cooler using absorbent like silica gel or
refrigerant dryers.
 Moisture Drain Traps
◦ Remove moisture in compressed air.
 Receivers
◦ Provide storage and smoothening pulsating air
output.
◦ Reducing pressure variation from compressor.

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 Mining
◦ Rock drilling and carriage systems
◦ Pneumatic hammer and chisels
 Plastic Industry
◦ Transport of granulate in pipes
◦ Ejecting work piece from production
 Textile Industry
◦ Thread detector
◦ Sewing needle and system cooling

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 Easily Transported
◦ Air is available everywhere
◦ Compressed air can be transported over great
distance in pipeline
 Easily Stored
◦ Easy to store compressed air in purpose-built tank
◦ Compressed air bottles can be used at location with
no pipe lines (underwater)
 Lightweight
◦ Pneumatic device lighter than equipment with
electrical power units.
◦ Pneumatic screw drivers and hammers
 Safe To Use
◦ Work perfectly when there are great temperature
fluctuation and the temperatures are extreme
◦ For operating forge presses and blast furnace doors
 Accident Proof
◦ Even in areas with risk of fire, explosion and
extreme weather, pneumatic element can be used.
 Fast Work Medium
◦ The very high flows speeds allow rapid completion
of work cycles.
◦ Provide short cut in time and fast conversion energy
to work

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Compressor
Dynamic
(Centrifugal)
Positive
Displacement
 There are two main categories of compressor -
dynamic and positive displacement. Almost all
pumps fall into one of these two categories.
 The main difference between dynamic and positive
displacement pumps lies in the method of fluid
transfer. A dynamic pump imparts velocity energy
to the fluid, which is converted to pressure energy
upon exiting the pump casing. A positive
displacement pump moves a fixed volume of fluid
within the pump casing by applying a force to
moveable boundaries containing the fluid volume.

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 Dynamic pumps can be further divided into two categories of pumps
- centrifugal and special effect. Special effect pumps include jet
pumps, reversible centrifugal, gas lift, electromagnetic and hydraulic
ram.
 Special effect pumps are not commonly used relative to centrifugal
pumps, so they will not be covered in this course. Positive
displacement pumps are also divided into two major pump
categories - reciprocating and rotary.
 Reciprocating pumps transfer a volume of fluid by a crankshaft,
eccentric cam or an alternating fluid pressure acting on a piston,
plunger or a diaphragm in a reciprocating motion. Rotary pumps
operate by transferring a volume of fluid in cavities located between
rotating and stationary components inside the pump casing.

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 compressor a cylinder bore encloses a
moving piston.
 As the crankshaft of the compressor rotate,
the piston moves within the cylinder, similar
to the piston in a car engine
 the piston is pulled down, the volume
increases, creating a lower atmospheric
pressure in the piston chamber.
 This difference in pressure causes air to enter
via the inlet valve
 This difference in pressure causes air to enter
via the inlet valve
 As the piston is forced upwards the volume of
air reduces
 The air pressure therefore increases.
Eventually the pressure forces the outlet valve
to open.

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 Reciprocating
◦ Most widely used
◦ They are characterized by a flow output that
remains nearly constant over a range of discharge
pressures.
◦ The compressor capacity is directly proportional to
the speed. The output, however, is a pulsating one.

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 Rotary Compressor
◦ Rotary compressors have rotors in place of pistons
and give a continuous, pulsation free discharge air
◦ Require smaller foundations, vibrate less, and have
a lower number of parts - which means less failure
rate.
4.2.4 Rotor Dynamic Compressor

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 uses a combination of the reciprocating action of a
rubber, thermoplastic or teflon diaphragm and suitable
non-return check valves to pump a fluid. ◦ Slide ram compressor
◦ Screw compressor

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The size of a compressed air reservoir depends on
the:
- Delivery volume of the compressor
- Air consumption for the application
- Network size
- Type of compressor cycle regulation
- Permissible pressure drop in the supply network

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 Free air delivery refers to harmonized
measure of the capacity of an air compressor.
To determine the free air delivery of a
compressor, the temperature and pressure at
the inlet of the compressor are required in
addition to the pressure and temperature of
the outlet air along with the volume
discharged.
ms4.18 Basic Pneumatic
System/Tieh SF 38
Simplified representation
 Air Service Unit
 Air filter with water
separator
 Pressure regulator
with pressure gauge
 Oil mist lubricator
Detailed representation
Pressure
regulating
valve
Lubricator
Filter
Pressure
gauge

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 Lubrication helps reduce friction between
sliding surfaces to not only improve efficiency
and increase cycling speed of a component,
but reduces wear, which ultimately means
longer component life and less maintenance.
 a device which removes contaminants from
a compressed air stream.
 This can be done using a number of different
techniques, from using a "media" type that
traps particulates, but allows air to pass
through to a venturi, to a membrane that only
allows air to pass through.

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 Proper compressor control is essential to
efficient operation and high performance.
 System master controls coordinate all of the
functions necessary to optimize compressed
air as a utility
 the ability to monitor and control all
components in the system, as well as
trending data, to enhance maintenance
functions and minimize costs of operation
 allow the removal of condensate from the
compressed air system.
 Automatic condensate traps are used to
conserve energy by preventing the loss of air
through open petcocks and valves.
 Poorly maintained traps can waste a lot of
compressed air.

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 Both a general purpose pre-filter and an oil
filter and an oil removal filter should be
installed just downstream of the
compressor aftercooler to remove solid
contaminants, water and oil.
 A dryer should be installed between the
aftercooler and receiver.
 Pressure drop between the receiver and the
point of use should be kept at a minimum.
The loss should be 3% or less of the line
pressure.
 The electric generator is the motor that is
used to compress air.
 At night, it uses electricity to create a
mechanical force, and in the daytime
mechanical power is applied to generate
electricity.

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Industry Example Compressed Air Uses
Food Dehydration, bottling, controls and actuators,
conveying, spraying coatings, cleaning, vacuum
packing
Textiles Agitating liquids, clamping, conveying,
automated equipment, controls and actuators,
loom jet weaving, spinning, texturizing
Apparel Conveying, clamping, tool powering, controls
and actuators, automated equipment
Lumber and
Wood
Sawing, hoisting, clamping, pressure treatment,
controls and actuators
Furniture Air piston powering, tool powering, clamping,
spraying, controls and actuators

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Industry Example Compressed Air Uses
Pulp and Paper Conveying, controls and actuators
Chemicals Conveying, controls and actuators
Petroleum Process gas compressing, controls and
actuators
Rubber and
Plastics
Tool powering, clamping, controls and
actuators, forming, mold press powering,
injection molding
Stone, Clay, and
Glass
Conveying, blending, mixing, controls and
actuators, glass blowing and molding, cooling
Primary Metals Vacuum melting, controls and actuators,
hoisting
Metals
Fabrication
Assembly station powering, tool powering,
controls and actuators, injection molding,
spraying
 Industrial facilities use compressed air for a
multitude of operations.
 Almost every industrial facility has at least
two compressors, and in a medium-sized
plant there may be hundreds of different uses
of compressed air.

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 A variable-speed drive (VSD) air
compressor is an air compressor that takes
advantage of variable-speed
drive technology. This type of compressor
uses a special drive to control the speed
(RPM) of the unit, which in turn saves energy
compared to a fixed speed equivalent
 The benefits of this technology included
reducing power cost, reducing power surges
(from starting AC motors), and delivering a
more constant pressure. The down side of
this technology is the heavy expense
associated with the drive, and the sensitivity
of these drives – specifically to heat and
moisture.

Basic Theory of Compress Air Plant Engineering

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