Centrifugal Pumps and Compressor.pdf [Autosaved].pptx

Centrifugal Pumps
and
Compressor

Machinery Maintenance Practices Overview
Maintenance procedure and preparation
Basics of Plant Equipment Functionality and Operation
Pumps Classifications and Selections
Troubleshooting of Centrifugal Pumps
Compressor Classifications and Selections
Diagnostic Techniques for Compressor Troubleshooting
Program Content :-

Time Money
Resources Life
Why Maintenance

Quality
Efficiency
Safety
Operation Criteria

Breakdown
Anticipation
Production
Readiness
Plan
anticipation
Maintenance Goals

MAINTENANCE PROCEDURE
WORK ORDER
PLANNING
PERMIT TO WORK (P.T.W) AND TAGGING
SAFETY DURING MAINTENANCE WORK
TROUBLESHOOTING

WORK ORDER
Investigation
Wrong
Cause
to be done
how long

PLANNING
Analyze
Contractor Or
Manpower
Material And Parts
Basic Approach
Overhauled
Replaced
Phased Out
Operation Effect

Isolate The
Equipment Or
System
Put The Tag On
That.
Work Permit
Classification
Authorization
operations
supervisor
needed it to
remove the tags
When Work
Done
PERMIT TO WORK (P.T.W)

Beating, Grinding, Welding, Burning,
Cutting, Using An Air Hose
Hard Hat Gloves
Safety
Glasses
SOLVENTS ( skin
irritations , volatile ,
inhaled cause illness,
death)
Respiratory Boots
Tagging out safety preparations

A mechanical
Aid Should Be
Used To Move
Anything Over
Fifty Pounds.
The Buddy
System Should
Used Whenever
Any Hazardous
Job Is Being
Performed
Moving Heavy Loads Is Often A Part Of Maintenance Work
Squatting Down,
Keeping The Back
Straight,
And Using The
Legs For Leverage.

Troubleshooting
Step One: Identify
distracting features
to isolate the
essential core.
Step Two: Analyze
that central issue

Troubleshooting Manual
•machinery history record logged
Troubleshooting Reference

Machinery History Record Logged
The Work Done On A Component Since Its Installation.
Initial Tests,
Maintenance Performed On A Piece During Its Operation.
Baseline Readings Difference May Indicate A Problem
Eventual Solutions,
Time Required For Repair,
Tool Used, Parts Number
Names Of Personnel Who Helped Solve Problems

Troubleshooting Manual
Symptoms Probable Cause
Possible Solutions

Strategies Run-to- Failure Failure-based
Preventive Time-based
Predictive Condition-based

lube oil analysis
contamination.
Acid
overheating
oxidizing

Thermographs Tribology
Vibration
Analysis
Ultrasonic
monitoring
Visual
Inspection
Predictive Maintenance Techniques

Thermographs
Infrared Energy
Emitted
Transmitted
Reflected

Tribology
Wear
Friction
Lubrication

Ferrography
wear particles a microscopic
examination and analysis

Vibration
Temperature
Pressure
Flow
Current
Detection of machine faults Parameters

Why Do We Prefer Vibration Monitoring As a PdM Technique?
• Vibration data can help us identify faults or detect warning signs of
potential failures. It can also aid in the detection of misalignment or
unbalance of assets such as bearings and rotating pieces of equipment.
• Vibrations generally had two influences: first, particles reached a higher
average temperature, and second, they attained more uniform temperature
distribution. The particles average temperature generally increased by
increasing vibration amplitude and frequency
• The effect of the flowing fluid is to reduce the frequencies of vibration and
to increase the damping when the flow velocity is low. As the flow velocity
increases, some roots cross the real axis and the system loses stability by
flutter.

These open-loop control systems operate
on a fixed schedule or input setting, without
adjusting to changes in the environment or
the output.
This can lead to inefficiencies or
inaccuracies in the system's performance.

In a closed-loop control system, this feedback loop
is used to continuously monitor and adjust the
output of the system, ensuring that it remains within
a desired range or set point.
This allows the system to adapt to changes in the
environment or input, providing more accurate and
reliable control compared to open-loop control
systems

• 1. Automatic doors: Automatic doors in public places such as shopping
malls or airports use an open-loop control system to open and close the
doors. Sensors detect the presence of a person and trigger the doors to
open for a fixed amount of time, after which they close automatically.
• 2. Traffic signals: Traffic signals use an open-loop control system to
regulate the flow of traffic at intersections. The signals operate on a
fixed timing schedule, with no feedback mechanism to adjust the
timing based on traffic volume or other factors.
Examples Of Open-loop Control Systems

Examples Of Closed Loop Control System
99Electric Oven
controlled
variable
is the internal
oven
temperature
manipulated
variable
power supplied
to the heating
elements+
disturbances external factors
oven door,
room
temperature
properties
amount of food
inside the oven.

Main
Components
A Sensor
Control Variable
Disturbances
Providing
Feedback To
The Controller.
A Controller
Processing The
Sensor Data
Computing
Response
Sent Actuator
An Actuator
Converting The
Input Into An
Output
Adjust The
Manipulated
Variables
Feedback in a control system consists of

C.F
Stage
Single
Multi
Arrangem
ent
Parallel Flow Rate
Series Pressure
PD
Reduce
Volume
Within
Pump
Variable
V
P
H = Hs –
Hd (Sam
Level )
H = H Lift
(atm ) + H
dis
Axis Of
Rotation
Dis/Suc
Casing
V to p
Diff Vane
Impeller
Shape Of
The Van
Redial
Single
Double
Open
Semi
Open
Shrould
one Side
Closed
Shrould
Double
Side
V/v
C/H
R/N
Primming
Vent
Vacum
Ejector
C.V/v
Priming
Tank
Warming
Shaft
Bearing
(Ball/
Roller )
Redial
Thrust
Frame
Assemply
Packing
Box
Lannon
Ring
Ext Lub
Mechanic
al Seal
Int Lub
Hard Face
Metal –
Stationary
Non
Metallic –
Carbon
Ring –
Rotate
Contact
Spring
Ring
Adjustabl
e Packing
Gland
Cavitation NPSH
Increase
Head
Pressure
Decrease
Required
Available

Hydraulic Basics Course
Lesson 1.0 Pump

Displacement
Rotary
Vane
Screw
Gear
Lobe
Reciprocating
Piston
Diaphragm
Pump Classifications Class1

Positive-Displacement Pumps
• By definition, PD pumps displace a
known quantity of liquid with each
revolution of the pumping elements
(i.e., gears, rotors, screws, vanes).
• PD pumps displace liquid by creating a
space between the pumping elements
and trapping liquid in the space. The
rotation of the pumping elements then
reduces the size of the space and
moves the liquid out of the pump.
• PD pumps can handle fluids of all
viscosities up to 1,320,000 cSt SSU,
capacities up to 1,150 M3/Hr and
pressures up to 700 BAR / 10,000 PSI.
• Rotary pumps are self-priming and
deliver a constant, smooth flow,
regardless of pressure variations.

Crescent Pump (Internal Gear)
• This pump consists of two rotating gears;
an Internal Gear with the teeth on the
outside, and an External gear with the
teeth on the inside. The External Gear is
larger and has more teeth, but the teeth
are the same size.
• As the teeth separate (lower left side in
this drawing) they pass over the intake
hole they "suck" in fluid, then the gears
are separated by a Crescent Seal (shown
in brown.)
• When the teeth start to come together
again (upper right here) they squeeze the
fluid through the outlet hole
• Normally the inner gear is attached to a
drive shaft and the outer gear is turned
by the inner gear at the point of contact
(upper left area of this drawing.)
• Advantages of the crescent pump include
its simple design and low maintenance
requirements.

b. Positive-Displacement Pumps. With this pump, a definite volume of liquid is
delivered for each cycle of pump operation, regardless of resistance, as long as the
capacity of the power unit driving a pump is not exceeded. If an outlet is completely
closed, either the unit driving a pump will stall or something will break. Therefore, a
positive-displacement-type pump requires a pressure regulator or pressure-relief valve in
the system. Figure 3-2 shows a reciprocating-type, positive-displacement pump.
Lesson 1.0 Pump

Gerotor Pump
• Gerotor pumps are positive
displacement pumps using nested
hypocycloid gear elements as their
pumping mechanism. The name
gerotor is derived from the phrase
generated rotor, and describes the
mathematical procedure for
generating the shape of the inner
rotor from the outer rotor.
• In a gerotor pump, either the
inner or the outer element is
driven by a motor, and this
element then drives the other.

Gear Pump
• For simple systems with a relatively low level of pressure (about 140 to
180 bar) the gear pump is the most used type of pump.
• The gear pump is a very simple, reliable, relatively cheap and less dirt
sensitive hydraulic pump.

Gear Pump, 2-Lobe
• This type of gear pump has
two lobes on each shaft. The
lobes nearly touch each other
in the center forming a fairly
tight seal.
• They also nearly touch the
casing and when they revolve
they carry fluid around the
outer edge to the outlet, at
the top in this drawing.
• This type of gear pump is
often used as a supercharger
for diesel engines, forcing air
(not liquid) into the power
cylinder.

Gear Pump, 3-Lobe
• This is a basically a type of
Gear Pump but with lobes
instead of gears.
• The three-lobe gear pump,
like the two-lobe version, is
commonly used to force
high-pressure air into
combustion compartments
of a diesel engine.
• The output of these pumps is
more pulsed than the output
of a gear pump because
there are fewer teeth. The
fluid is delivered in
comparatively larger packets.

Star Pump
• The inner gear is usually the drive
gear and pushes the outer, larger
gear around. A tight fit where the
gears mesh keeps fluid advancing
around the pump.
• The dark kidney-shaped hole on
the right is the intake and the one
on the left is the outlet. As the
teeth on the two gears separate
the suction draws in the liquid.
• This pump is best used for
pumping lubricating fluids such as
oil because the teeth must rub
against each other somewhat. The
amount of rubbing is slight but not
insignificant.
• Star pumps are also called
GEROTOR PUMPS and the gears
are called gerotor gears.
The STAR PUMP consists of a
rotating star shaped gear inside of
another gear. The inner gear has
one less tooth than the outer gear.

Screw Pump
• The screw pump is a positive
displacement pump which
comes with two or three screws.
• The pump forms hollow cavities
which contain the fluid and
move it along the screws. One
screw is the drive screw and the
other screw or screws is/are
driven by the drive screw.
• The two-bladed pump shown
here has a plexiglass casing so
that the internal gearing can be
seen.

Quimby Screw Pump
• Quimby Screw Pumps use closely
matched screws which mesh to form
pockets of fluid. Each shaft has a left-
hand screw and a right-hand screw, for
hydraulic pressure balance.
• On the left is a side view and a top (or
bottom) view. The inlet is at each end
and the outlet is in the middle. The
two shafts are geared together and
revolve at the same rate, up to about
1750 RPM.
• Quimby Screws often pump oil, which
lubricates the meshing gears. They
have no valves or small parts to wear
out or break, and the stuffing boxes
are in the low pressure part of the
pump where they are less prone to
wear.
• A Quimby Screw can pump 4,000
gallons per minute at 1,000 P.S.I.

Vane Pump
• The vanes are in slots in the rotor.
When the rotor spins, centrifugal
force pushes the vanes out to touch
the casing, where they trap and
propel fluid. Sometimes springs also
push the vanes outward.
• When the vanes reach the return
side they are pushed back into the
rotor by the casing. Fluid escapes
through a channel or groove cut into
the casing, shown here on the lower
right side in black.
• On this vane pump there is
considerable unbalanced force on
the drive shaft, since the high-
pressure, outlet area is all on one
side. Vane pumps can be designed in
balanced configurations where there
are two inlet and two outlet ports.
•A very common type of pump,
this is one of many variations.
•Power steering units often rely
on a vane pump to obtain the
pressure needed for the Power
Cylinder. Automatic transmissions
often use them too.

Vane Pump
• On many industrial
installations with a
maximum pressure of
about 200 bar, vane
pumps are applied.
• The advantage of vane
pumps is the pulse free
delivery and low level of
noise.
• The shaft of the rotor
with the radial mounted
vanes is driven by an
engine or motor.

Piston Pump
• The basic Piston Pump is very
simple having just two valves
and one stuffing box.
• In this example the
reciprocating piston is driven
back and forth by a rotating
mechanism.
• This piston pump uses suction
to raise water into the chamber.
The lower valve can be placed
below water level.
• The piston must be within
about 25 feet of the water
level, but the water can then be
raised quite high.

Force Pump, Double Acting
• This pump is more efficient that a
single-acting force pump such as a
simple Lift Pump or a hand-operated
Bilge Pump.
• Each stroke of the piston fills one
chamber and empties another, which
nearly doubles the flow rate (less the
volume of the piston rod) over a
single-acting force pump. It also
smoothes the flow.
• From the outside this pump can take
many forms, but the basic principal of
operation will be identical.

Diaphragm Pump
• Cars often use a Diaphragm Pump to move
gasoline from the gas tank to the carburetor or
fuel injection plugs.
• The gasoline diaphragm pump is operated by a
cam geared directly to rotating parts of the
engine. The cam pushes a pushrod.
• The brown rod shown in this drawing is moved
by the pushrod. It pushes the diaphragm in (a
spring forces it back out.)
• Fuel pumps like this one operate continuously
but have a safety valve which returns fuel to the
input side of the pump if pressure rises above a
set level.
• Diaphragm pumps are very common and come
in many sizes. Modern plastics are flexible and
long lasting making this an ideal low-
maintenance pump for many applications.

Double-Diaphragm Pump
• Double Diaphragm pumps offer smooth flow, reliable
operation, and the ability to pump a wide variety of
viscous and impure liquids. The Air Operated Double
Diaphragm pump is illustrated. This pump uses a very
simple valve system to move the DIAPHRAGM ROD.
The flexible diaphragms are round disks attached at
each end of the Diaphragm Rod.
• The PILOT SPOOL (the middle of the three
horizontal rods) is pushed back and forth whenever
the Diaphragm Rod reaches the end of its throw. The
Pilot Spool allows air to move the Air Distribution
Valve (the top rod in this drawing) back and forth.
• The AIR DISTRIBUTION ROD controls air flow to
the left or right air chamber, reversing on each stroke.
• The four BALL VALVES are free-floating and
operated by pressure differences in the pumped liquid.
Flapper valves are also commonly used. Liquid flow is
from the bottom to the top.
• Sanitary Double Diaphragm pumps, often made of
plastic and/or stainless steel, are used in the food
industry to pump everything from sliced fruit, to
sausage, to chocolate.

. With this pump, the volume of liquid delivered for each cycle depends on the
resistance offered to flow. A pump produces a force on the liquid that is constant for
each particular speed of the pump. Resistance in a discharge line produces a force in
the opposite direction. When these forces are equal, a liquid is in a state of
equilibrium and does not flow.
If the outlet of a nonpositive-displacement pump is completely closed, the discharge
pressure will rise to the maximum for a pump operating at a maximum speed. A
pump will churn a liquid and produce heat. Figure 3-1 shows a nonpositive-
displacement pump. A water wheel picks up the fluid and moves it.
a. Nonpositive-Displacement Pumps

Dynamics
Centrifugal
Radial
Axial
Mixa
Pump Classifications Class 2

Screw Centrifugal Pump
The screw centrifugal impeller
provides several key benefits:
• Large free passages for pumping
liquid with solid objects and fibrous
materials
• Able to pump liquids and viscosity's
above values normally possible with
conventional centrifugal pumps
• Steep H/Q curves with closed valve
twice best efficiency point
• Low NPSH characteristics
• Flat non-overloading power curves
• High hydraulic efficiencies

Cavitation
• An undesired phenomena in
hydraulic system is cavitation.
Most of the time cavitation
occurs in the suction part of the
system. When cavitation takes
place the pressure in the fluid
decreases to a level below the
ambient pressure thus forming
'vacuum holes' in the fluid.
When the pressure increases, for
example in the pump, these
'vacuum holes' implode.

• During this implosion the pressure increases tremendously and the
temperature rises to about 1100 degrees Celsius. The high pressure in
combination with the high temperature, causes a lot of damage to
the hydraulic components. A cavitating pump might be completely
damaged in several hours and the wear parts may cause damage in
the system. cavitation can be caused by:
acceleration of the oil flow behind a throttle or when the oil contains
water or air
high fluid temperature
a resistance in the suction part of the system
a suction line which is to small in diameter
a suction hose with a damaged inside liner
a suction filter which is saturated with dirt (animation)
high oil viscosity
insufficient breezing of the reservoir

cavitation occurs when the pressure of a liquid drops below its
vapor pressure, causing the formation of vapor bubbles that can
collapse and generate damaging pressure changes

Bernoulli equation tells us that fluid speed and pressure are
related. When speed increases, pressure decreases, and when
speed decreases, pressure increases.

NPSH
NPSHR is the minimum suction
pressure a pump requires to avoid
cavitation. This is specified by the pump
manufacturer. NPSHA is the actual
suction pressure the system can provide
to the pump inlet. This depends on
piping, tank levels, flowrate. NPSHA
must be greater than NPSHR to prevent
cavitation. This provides the net positive
suction head. Cavitation occurs when
liquid vaporizes due to low inlet
pressure, forming bubbles that collapse
violently. If NPSHA < NPSHR, there is
insufficient net positive suction head
and cavitation occurs.

pressure drop in a heat exchanger can increase fluid velocity,
which may lead to cavitation if the pressure drops below the vapor
pressure of the fluid. The Bernoulli equation helps us understand
the relationship between fluid velocity and pressure,

imagine blowing air into a glass of water through a straw. As you blow air, you
create low-pressure regions in the water near the straw. If the pressure drops low
enough, you might see small bubbles forming. When you stop blowing and the
pressure normalizes, the bubbles collapse, making a popping sound. In a similar
way, cavitation in a heat exchanger involves the formation and subsequent collapse
of tiny vapor bubbles within the liquid.

Motor Coupling Shaft
Stuffing box
• Mechanical
• Gasket
Case
Pipe In/Out
Impeller Control Valve

• Oil degradation: Excess oil can cause the lubricant to overheat and oxidize, resulting in
sludge formation, viscosity increase, and additive depletion1. This can reduce the
lubricant’s ability to protect the bearings and other components from wear and
corrosion. Oil degradation can also lead to seal failures, as the oil may leak into the
process fluid or the atmosphere
• Bearing distress: Over-lubrication can create excessive pressure and heat in the bearing
housing, which can damage the rolling elements, cages, and races of the bearings1.
• Over-lubrication can also cause oil rings to slip or skip on the shaft, resulting in poor oil
distribution and increased friction1. Moreover, over-lubrication can interfere with the
balancing holes that are designed to equalize the air pressures on each side of the
bearings2. This can cause axial thrust and vibration problems
• Increased power consumption: Over-lubrication can increase the drag and resistance in
the bearing housing, which can reduce the pump efficiency and increase the power
consumption. This can also increase the operating costs and carbon footprint of the pump.
Why Over-lubrication Can damage ?!

Valve Testation
Cleaning Pre Installing
how to correctly pack the gland of a valve
• Stem Damage Due packing rings be installed with
the butts hard against each other.
• Instead provide sufficient breathing1/16 inch gap
Between packing rings butts .

Globe Valve
• slacken back when the valve opened hard against the back
seat. This often happens when a valve cheater bar or
wrench is used to open the valve
Bearing
• 150% Vertical Movement More Than Original Clearance
Valve Cases

Centrifugal
Operation
Pattern
Motor AMPS
Vs Fluid S.G
@ > Specific
Viscosity
RPM Vs
Discharge Head
Function Fluid
S.G
As Bernolies
Law

Mechanical System
Motor Coupling Shaft Stuffing box
Mechanical Gasket
Case
Pipe
In/Out
Impeller
Control
Valve

MECHANICAL
SEAL
he primary function of a mechanical
seal is to prevent fluid leakage from
the pump. It creates a barrier
between the rotating shaft and the
stationary housing, ensuring that the
fluid being pumped stays contained
These two parts have special
surfaces that fit together tightly to
create a seal. When the pump is
running, they are pressed together
by a spring or another device,
ensuring a tight connection between
them.

Vacuum
Candle
Flame
Plastic
Wrap
Dye Pressure
Leak Test

Candle Flame
smoke test,
safety hazard,
and appropriate
precautions
Isolate
smoke trail is
directed
smoke to be
drawn out of
leaks
identified path
of the smoke
trail.
Leak Test

•Dye
Isolate Injected
Fluorescent Dye
back into service
inspected using
a UV light
identify any
areas where the
dye has escaped.
may not be
effective for
detecting very
small leaks

Vacuum
pump
Gauge
Plastic Wrap
leak detection solution
applied to the external
surface of the area
suspected
solution create a visible
mark around the affected
area
colored dye
specific application
type of Fluid

Heat Exchanger and Fired Heater
Operation & Troubleshooting

turbulence of the fluid,
which leads to an increase
in the number of eddies
and vortices in the fluid.
These eddies and vortices
enhance the mixing of the
fluid, which increases the
rate of heat transfer
between the fluid and the
solid surface..

Elements Influencing the
Corrosion Speed of Metals
Temperature
Hygroscopic
salts
Aerobic
conditions
bacteria on
the metal
surface
Bi-metallic
contact.
Acids and
alkalis

Corrosion Triangle
Electrolyte
Anode
Corrosion
Cathode

Cathodic
Protection
The principle of cathodic protection
is to connect an external anode to
the metal to be protected and to pass
a DC current between them so that
the metal becomes cathodic and
does not corrode In Order To
Reverse electrochemical process Of
Corrosion Which normally
occurring at the anode

Classification of air
compressors

What are compressors?
Compressors are mechanical devices that
compresses gases. It is widely used in
industries and has various applications

What are its applications?
Compressors have many everyday uses, such as in :
• Air conditioners, (car, home)
• Home and industrial refrigeration
• Hydraulic compressors for industrial machines
• Air compressors for industrial manufacturing
Refrigeration compressor

What are its various types?
Compressor classification can be described by following flow chart:

What are positive displacement
compressors?
Positive displacement compressors causes movement by trapping a fixed
amount of air then forcing (displacing) that trapped volume into the discharge
pipe.
It can be further classified according to the mechanism used to move air.
Rotary Compressor
Reciprocating compressor

What are dynamic compressors?
The dynamic compressor is continuous flow compressor is characterized by rotating
impeller to add velocity and thus pressure to fluid.
It is widely used in chemical and petroleum refinery industry for specific services.
There are two types of dynamic compressors
 Centrifugal Compressor
 Axial Flow Compressor

Positive Displacement-Rotary compressors-
Lobe

screw

scroll type

Vane type

Reciprocating compressor
It is a positive-displacement compressor that
 Uses pistons driven by a crankshaft to deliver
gases at high pressure.
The intake gas enters the suction manifold, then
flows into the compression cylinder
It gets compressed by a piston driven in a
reciprocating motion via a crankshaft,
Discharged at higher pressure

Positive Displacement-Reciprocating
compressors-Diaphragm type

compressors-single acting Piston type

compressors-double acting Piston type

Dynamic compressors
The dynamic compressor is continuous flow compressor is characterized by rotating
impeller to add velocity and thus pressure to fluid.
It is widely used in chemical and petroleum refinery industry for specific services.
There are two types of dynamic compressors
 Centrifugal Compressor
 Axial Flow Compressor

Dynamic compressors:Centrifugal
Compressor
Achieves compression by applying inertial forces to the gas by means of
rotating impellers.
It is multiple stage ; each stage consists of an impeller as the rotating
element and the stationary element, i.e. diffuser
 Fluid flow enters the impeller axially and discharged radially
 The gas next flows through a circular chamber (diffuser), where it loses
velocity and increases pressure.

Dynamic compressors: Axial flow compressor
Working fluid principally flows
parallel to the axis of rotation.
 The energy level of air or gas
flowing through it is increased by the
action of the rotor blades which exert a
torque on the fluid
Have the benefits of
high efficiency and large mass
flow rate
Require several rows of
airfoils to achieve large
pressure rises making them
complex and expensive

Why multistage compressor?
High temp rise leads into limitation for the maximum achievable pressure
rise.
Discharge temperature shall not exceed 150ºC and should not exceed 1350C
for hydrogen rich services
A multistage centrifugal compressor compresses air to the required
pressure in multiple stages.
Intercoolers are used in between each stage to removes heat and decrease
the temperature of gas so that gas could be compressed to higher pressure
without much rise in temperature
Intercooler

Advantages and Disadvantages of dynamic compressors
Advantages Disadvantages
Dynamic
Compressors
Centrifugal •Wide operating range
•High reliability
•Low Maintenance
•Instability at reduced flow
•Sensitive to gas composition
change
Axial •High Capacity for given
size
•High efficiency
•Heavy duty
•Low maintenance
•Low Compression ratios
•Limited turndown

Advantages and disadvantages of positive displacement
type compressor
Advantages Disadvantages
Positive displacement
compressor
Reciprocating •Wide pressure ratios
•High efficiency
•Heavy foundation required
•Flow pulsation
•High maintenance
Diaphragm •Very high pressure
•Low flow
•No moving seal
•Limited capacity range
•Periodic replacement of
diaphragm
Screw •Wide application
•High efficiency
•High pressure ratio
•Expensive
•Unsuitable for corrosive or dirty
gases

What is a compressor?
A compressor is a mechanical
device that produces flow and/or
pressure in a fluid by the
expenditure of work. Usually used
to handle large volumes of gas at
pressure increases from 10.32KPa
to several hundred KPa.

Types of Compressors
Continuous-flow compressors (operate by
accelerating the gas and converting the energy
to pressure)
• Centrifugal
• Axial flow
Positive Displacement compressors (operate by
trapping a specific volume of gas and forcing it
into a smaller volume)
• Rotary
• Reciprocating

Compressor Selection
Centrifugal – Used for medium to high
pressure delivery and medium flow
Axial Flow – Used for low pressure and
high flow
Positive Displacement - Used for high
pressure and low flow characteristics

Compressor Selection
Factors to be considered:
1. Flowrate
2. Head or pressure
3. Temperature Limitations
4. Method of Sealing
5. Method of Lubrication
6. Power Consumption
7. Serviceability
8. Cost

Multistage Compressor
11
9
■ Multistage containing a series of impellers on a
single shaft rotating at high speed in a massive
casing internal channel
■ It lead from the discharge of one impeller to the
inlet of next these machines and compress measure
volumes
• of air.

Surge
■ Surge is the BACKFLOW of gas in compressor.
■ Sustain oscillation
■ Important element it protects the compressor from
surge over the range of compressor operations.
12
1

Surge Description
12
2
■ Flow reverses in 20 to 50 milisec.
■ Surge cycle at a rate of 0.3 to 3 sec.
■ Compressor Vibrates.
■ Temperature rises.
■ Whooshing noise.
■ Trips may occur.

Compressor Operating Curve
Hp
Q
1
3
1. STONEWALL POINT
2. NORMAL POINT
3. SURGE POINT
MAX.STABLE COMP. FLOW POINT
12
3
MIN.STABLE FLOW POINT
.
2

Development of Surge Cycle
12
4

Development of Surge Cycle
From B TO C 20-50 ms
From D TO A 20-120 ms
ABCDA 0.3 TO 3 sec
12
5

Anti-surge control system
14
DISCHARGE
SUCTION
VALVE TAKES COMPRESSOR
AWAY FROM SURGE
R PROCESS
R PROCESS
+VALVE
RECYCLE VALVE

In positive displacement compressors, such as reciprocating and rotary
pumps, an increase in viscosity can actually improve performance. This is
because higher viscosity reduces leakage (also known as slip), which
increases the displacement volume and volumetric efficiency2.
However, as viscosity increases, there is additional resistance to shear. This
typically results in a small reduction in flow, a more significant reduction in
head or pressure, and a substantial increase in power draw

Liquid Ring

Anti-surge control operation
SLL
SCL
A
B
WHEN OPERATING POINT CROSSES
SCL, PI CONTROLLER WILL OPEN
RECYCLE VALVE
SUITABLE FOR SMALL DISTURBANCE
Output
CLOSE LOOP CONTROL PI
to valve
Tim
e
Medium disturbance
12
9
100%
C
0%

ADAPTIVE GAIN
SLL
SCL
b
WHEN THE OPERATING POINT MOVES FAST
TOWARD SCL , ADAPTIVE GAIN MOVES
THE SCL TOWARD OPERATING POINT
THIS ALLOWS THE PI CONTROLLER TO
REACT EARLIER
Large disturbance
SUITABLE FOR FAST DISTURBANCE
Output
to valve
Tim
e
Total
PI Control
C
13
0

RECYCLE TRIP LINE
SLL
SCL
A
B
C
OPERATING POINT MOVES BACK
TO SAFE SIDE OF RTL
RTL
OPERATING POINT HITS RTL
OPEN LOOP RESPONSE IS TRIGGERED
VALVE
TOTAL
RTL
PI
PI Control
Recycle Trip®
Action
+
To antisurge valve
O/P
13
1

SAFETY ON LINE (SOL)
SOL
13
2
SLL
RTL
SO RESPONSE SHIFTS THE SCL AND
SCL RTL TO RIGHT
IF OPERATING POINT CROSSES
THE SOL LINE THE COMP IS IN SURGE
SO ADDITIONAL SURGE MARGIN IS
ADDED
BENEFITS OF SOL
1.ADDITIONAL SURGING IS
AVOIDED BY LARGE SURGE
MARGIN
2.ALARM OF SURGE IS
PRODUCED

Conclusion
13
3
What we have presented so far in this presentation is that what is surge and it’s
generation. In this presentation we discussed characteristics of compressor,
phenomenon of surge like surge process, surge cycle, surge point, surge line,
surge control line, surge margin etc. We also mentioned here causes of surge in
centrifugal compressor and it’s effect and consequence centrifugal compressor
and also the prevention of surge occurrence(Anti-surge system).

Reciprocating Compressor
Principles, Construction &
Design Philosophies

BASIC COMPONENTS
CONNECTING ROD
CROSSHEAD
PISTON
VALVE
PISTON ROD
PISTON ROD
PACKING
PISTON
CYLINDER
CRANKSHAFT
CRANKCASE

Pressure-Volume Diagram
The P-V diagram (pressure-volume diagram) is a plot of the pressure inside the compression chamber
(inside the bore) versus the volume of gas inside the chamber. A complete circuit around the diagram
represents one revolution of the crankshaft. This is an “ideal” diagram in that it does not show any valve
pressure and therefore no valve loss horsepower. PD is discharge pressure (typically said to be the
pressure that exists at the cylinder flange). PS is suction pressure.
THEORY OF OPERATION:

This depicts the compression event. It starts at the point where the suction valve closes. When the suction
valve closes, gas is trapped inside the compression chamber at suction pressure and suction temperature.
As the piston moves towards the other end of the compression chamber, the volume is decreasing, the
pressure increasing and the temperature increasing. Compression stops when the discharge valve opens.
The shape of the curve of the compression event is determined by the adiabatic exponent (k-value or n-
value).
Compression

When the discharge valve opens, compression stops, and gas at discharge pressure and discharge
temperature is pushed out of the compression chamber through the discharge valve, into the discharge
gas passage and out into the discharge piping. The discharge event continues until the piston reaches the
end of the stroke, where the discharge valve closes and the next event, expansion, begins. The
compression and discharge events together represent one-half of one revolution of the crankshaft and
one stroke length.
Discharge

When the discharge valve closes at the end of the discharge event, there is still some gas left in the
compression chamber. This volume of gas is referred to as the “fixed clearance volume” and is usually
expressed as a percentage. As the piston moves away from the head, the volume inside the compression
chamber increases with all of the valves (suction and discharge) closed. The gas in the fixed clearance
volume expands, decreasing in pressure and temperature, until the pressure inside the compression
chamber reaches suction pressure, where the suction valve opens and the expansion event ceases.
Expansion

Suction
At the end of the expansion event, the suction valve opens opening the compression chamber to the
suction gas passage and suction piping system. As the piston moves, the volume in the compression
chamber is increasing and the compression chamber fills with gas at suction pressure and suction
temperature. The suction event ceases when the piston reaches the other end of the stroke, the suction
valves closes and the piston turns around and goes the other direction. The end of the suction event
marks the end of one complete cycle. One complete cycle requires one complete revolution of the
crankshaft and two stroke lengths.

COMPRESSOR VALVE TYPES:
Valves are key components for the successful operation of a piston compressor. They are the most
stressed components of the compressor. Their perfect operation is decisive for the delivery of the gas.
According to a study, more than one third of all compressor-related shut-downs are caused by valve
problems. The most important valve types are– plate, ring and poppet valves. The common feature of
these valves is that they are self-acting, i.e. by means of differential pressure. The principal components
are the valve seat, stroke limiter and central bolt together with sealing elements in the form of plates,
rings or poppets and their associated spring elements and spacer rings.

1. PLATE
The plate valve is the oldest self-acting design. Concentric rings joined together by radial connections
with the appropriate spring constitute the sealing element. Depending on the design, one or more
damper plates are employed. Metal or plastic material is used for the valve and damper plates. Plate
valves have large flow areas, but they have unfavorable flow characteristics. The gas has to be
deflected twice through 90°, which leads to corresponding valve losses.

Open Position Close Position
Valve Seat Body
Seat Plate Valve Spring
Valve Guard
Cross-Sectional View

2. RING
The sealing elements of ring valves comprise single rings that are always made of plastic. Ring valves are
among the most flow-effective valves, because gas can flow through the valve with only slight deflections.
This leads to lower losses, despite their smaller flow areas. Further advantages of this valve are its simple
assembly and the stable form of the sealing elements, which reduces the risk of fracture. A further
positive feature is that foreign particles can embed themselves in the plastic material, and so they are
more robust than comparable metal-plate valves. Moreover, there is less danger of clogging by
condensing gases or gases containing hard particles. The machining of the valve seats during refurbishing
of ring valves is even more complex. In addition, plastic is not suitable as a ring material for some gases,
and high-temperature plastic rings cost considerably more than metal plates.

3. POPPET
Poppets have been used in the earliest valve designs for
compressors. Weight and impact forces limited the use of
bronze and steel poppets. The modern poppet valve was
introduced in the 1950's. It used mushroom shaped sealing
elements made of metallic materials or thermoplastics. The
poppet material determines the application range of the
valves. The use of metallic poppets limits the compressor
speed to about 450 rpm. The development of heavy-duty
thermoplastic materials like PEEK and their application for
sealing elements has extended the range for poppet valves
significantly. Compressor speed of up to 1800 rpm,
temperatures up to 220°C and differential pressures of 100
bars are no longer a problem. Their characteristics are very
similar to those of ring valves. They also have effective flow
characteristics, i.e., the losses in the sealing gap are lower
than those of plate valves. Poppet valves are less likely to
leak at higher temperatures, because geometric distortions
and thermal expansion of the poppets do not have any
negative effects. One disadvantage, however, is the larger
number of sealing elements, with which the failure
probability of a single element increases. Nevertheless, this
point can also be viewed in a positive manner, because
further operation is possible even if individual poppets
should fail for a certain period of time.

Centrifugal Compressor
Principles, Construction &
Design Philosophies

THEORY OF OPERATION:
Centrifugal compressors accelerate 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.
Centrifugal force is utilized to do the work of
the compressor. The gas particles enter the
eye of the impeller designated D in the figure
shown. As the impeller rotates, air is thrown
against the casing of the compressor. The air
becomes compressed as more and more air is
thrown out to the casing by the impeller
blades. The air is pushed along the path
designated A, B, and C in the figure. The
pressure of the air is increased as it is pushed
along this path. Note in the figure that the
impeller blades curve forward. Centrifugal
compressors can use a variety of blade
orientation including forward and backward
curves as well as other designs. There may
be several stages to a centrifugal compressor
and the result is that a higher pressure would
be produced.

Figure 1 – Dry Gas Seal Cross-section
PRIMARY SYSTEM SEALING:

Dry gas seals have been applied in process gas centrifugal compressors for over 20 years. Over 80
percent of centrifugal gas compressors manufactured today are equipped with dry gas seals. Dry
gas seals are available in a variety of configurations, but the "tandem" style seal (Fig. 1) is
typically applied in process gas service. Other types of gas seals (such as double opposed) are not
considered. Tandem seals consist of a primary seal and a secondary seal, contained within a single
cartridge. During normal operation, the primary seal absorbs the total pressure drop to the user's
vent system, and the secondary seal serves as a backup should the primary seal fail. Dry gas seals
are basically mechanical face seals, consisting of a mating (rotating) ring and a primary
(stationary) ring (Fig. 2). During operation, grooves in the mating ring (Fig. 3) generate a fluid-
dynamic force causing the primary ring to separate from the mating ring creating a "running gap"
between the two rings. Inboard of the dry gas seal is the inner labyrinth seal, which separates the
process gas from the gas seal. A sealing gas is injected between the inner labyrinth seal and the
gas seal, providing the working fluid for the running gap and the seal between the atmosphere or
flare system and the compressor internal process gas.
Figure 3
Figure 2

The following are the general requirements before
overhauling the equipment:
•Make sure the system is purged and evacuated of hydrocarbons.
•Install spades at the necessary blinding points.
•Tools and other lifting devices delivered and installed on site.
•Coordination meeting on the extent of the job to be performed.
•Checklist and other information on clearances are available.

• Rod drop-out/ crosshead clearances
• Rod packing, oil scrapers and seals
• Deflection and Alignment on Crankshaft
• Valve condition
• General Clearances and Alignment
• Connecting rod/ Piston Rod
• Equipment Levelling
• Cleanliness
The following are the things to be inspected during the assembly and
disassembly process of the equipment:
As a prerequisite the following tests shall also be done in following parts
of the equipment:
• Dye Penetrant Testing of Pistons, Crossheads, Valves,
Main bearing metal, Cylinder liner and housing (if
necessary)
• Radiographic Testing on the piston nut and rod threads
RECIPROCATING COMPRESSORS:

• Impeller tip/seal clearances
• Drive bearings condition
• Dry gas seal condition
• General Clearances and Alignment
• Equipment Levelling
• Cleanliness
The following are the things to be inspected during the assembly and
disassembly process of the equipment:
As a prerequisite the following tests shall also be done in following parts
of the equipment:
• Dye Penetrant Testing of housing (if necessary)
CENTRIFUGAL COMPRESSORS:

For each particular design of compressor the maintenance
and overhauling manual should be provided by the
manufacturer. This should be the main reference of the
maintenance technician when doing the maintenance. All of
these are available in the library. The technician should
familiarize himself with all the details necessary for the
maintenance of the compressor as recommended by the
vendor.

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