This presentation covers the type of compressors, its application, capacity control methods, surge control, cooling system, advantage and disadvantage of compressors.

1. R. AJITHKUMAR
GET - PROCESS

2. CONTENTS
➢INTRODUCTION
➢TYPES OF COMPRESSOR
➢APPLICATION OF COMPRESSOR
➢COOLING SYSTEM
➢SURGE AND ANTI-SURGE CONDITIONS
➢CONTROLS AND INSTRUMENTATION
➢PIPING AND INSTRUMENTATION DIAGRAM
➢ADVANTAGE AND DISADVANTAGE OF TYPES OF COMPRESSORS
➢COMPRESSOR DATA SHEET
➢BATTERY LIMIT

3. INTRODUCTION
➢Compression of gases and vapours is an important operation in chemical and petrochemical plants.
➢Compressor is a mechanical device used to increase the pressure of compressible fluid, either gas
or vapour, by reducing the fluid specific volume during passage of the fluid through compressor.
➢Compressors are similar to pumps: both increase the pressure on a fluid and both transports the
fluid through a pipe. As gases are compressible, the compressor reduces the volume of the gas. But
the Liquids are relatively incompressible, while some can be compressed, the main action of a
pump is to pressurize and transport liquids.
➢The benefits of operating the gas at higher pressures includes the ability to transmit larger volumes
of gas through a given size of a pipeline, lower transmission losses due to friction, and the
capability to transmit gas over long distances without additional boosting stations.

4. TYPES OF COMPRESSOR

5. APPLICATIONS
➢Gas lift
➢Reinjection of gas for pressure maintenance
➢Gas gathering
➢Gas processing operations (circulation of gas through the process or
system)
➢Transmission and distribution systems
➢Reducing the gas volume for shipment by tankers or for storage

6. POSITIVE DISPLACEMENT COMPRESSOR
➢ Positive displacement compressors deliver a fixed volume of gas at high pressures.
➢ In all positive displacement machines, a certain inlet volume of gas is confined in a given space and
subsequently compressed by reducing this confined space or volume.
➢ At this elevated pressure, the gas is next expelled into the discharge piping or vessel system.
TYPES OF PDC
➢ Reciprocating compressor
➢ Rotary compressor

7. RECIPROCATING COMPRESSOR
➢Reciprocating compressors are positive displacement machines in
which the compressing and displacing element is a piston having a
reciprocating motion within a cylinder
➢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, and discharged at higher pressure

8. PV DIAGRAM

9. RECIPROCATING COMPRESSOR BASIC PARTS
➢ Cylinder
➢ Piston
➢ Crank shaft
➢ Connecting piece
➢ Bearing
➢ Compressor valves

10. CYLINDER
• Cylinder is a pressure vessel
• Single-acting cylinders compress gas in only one direction of piston travel
• Double-acting cylinders compress gas in both directions of piston travel.
• Most reciprocating compressors use double-acting cylinders.
MOC
• Cast iron = 1,000 psi.
• Nodular iron =1,500 psi.
• Cast steel = 1,500 - 2,500 psi.
• Forged steel = >2,500 psi
FROM API STANDARD 618

11. SINGLE ACTING DOUBLE ACTING
A Single Acting Reciprocating (piston)
compressor consists of a single cylinder which
only takes in and discharges fluid at one end.
A Double acting unit also has only one cylinder but
it is piped up to take in and discharge fluid at both
ends

12. PISTON
➢The piston is located at the end of the piston
rod and acts as the movable barrier in the
compressor cylinder
➢Its made-up of lightweight material
➢Aluminum
➢Cast iron
➢Steel
➢It have hollow cylinder for weight reduction

13. CRANKSHAFT
➢ The piston can perform reciprocating motion inside the cylinder because of the rotary motion of the crankshaft.
➢ On one side it is connected to the electric motor directly by the coupling or by the belt and pulley arrangement.
➢ The rotation of the motor shaft brings about the rotation of the crankshaft. On the other side the crankshaft is also
connected to the connecting rod, which is then connected to the piston at it other end.
➢ The rotary motion of the crankshaft is converted into the reciprocating motion of the piston by connecting rod.
➢ In case of the multi-cylinder compressors, the number of connecting rods connected to the crankshaft is same as the
number of cylinders.

14. DISTANCE PIECE
➢ The distance piece provides separation between the
compressor cylinder and the compressor frame
➢ Crosshead guide end of the piston rod is isolated
from the crankcase by a packing, which provides
seal to prevent leakages
BEARINGS
➢ Bearings located throughout the compressor frame assure
proper radial and axial positioning of compressor components.
➢ Main bearings are fitted in the frame to properly position the
crankshaft.
➢ Most of the bearings in reciprocating compressors are
hydrodynamic lubricated bearings.
➢ Pressurized oil is supplied to each bearing through oil supply
grooves on the bearing surface.

15. COMPRESSOR VALVES
• The essential function of compressor valves is to permit gas flow in the desired direction and to
block all flow in the opposite (undesired) direction.
• Each operating end of a compressor cylinder must have two sets of valves.
• The set of inlet (suction) valves admits gas into the cylinder.
• The set of discharge valves is used to evacuate compressed gas from the cylinder.
VALVE TYPE PRESSURE
(PSI)
DIFFERENCIAL
PRESSURE (PSI)
SPEED
(RPM)
TEMPERATURE
(C)
PLATE 15000 10000 2000 260
CONCENTRIC RING
VALVES
15000 10000 2000 260
POPPET-STYLE
VALVES
3000 1400 450 260

16. POPPET VALVE RING VALVE
PLATE VALVE

17. PULSATION
➢ The flow of gas through a reciprocating compressor inherently produces pulsation because the suction and
discharge valves are not open for the entire compression stroke.
➢ Pulsation damping is needed to create a more uniform flow through the compressor to assure uniform loading
and to reduce piping vibration levels.
PULSATION CONTROL DEVICES
➢ If long, straight runs of piping of the same diameter as the compressor cylinder line connection can be
provided, and the stage power is less than 150 hp, separate volume bottles or pulsation vessels may not be
required.
➢ For most applications, volume bottles or pulsation vessels with internal baffles and/or choke tubes should be
located as close to the cylinder as possible for optimum valve reliability.
➢ The addition of orifices at key locations in the piping can also reduce piping pulsations. Several different
bottle-sizing formulae are available. Typical bottle sizes are five to ten times the cylinder swept volume.

18. LUBRICATION
FRAME LUBRICATION
➢The frame lubrication system delivers oil to the frame bearings, connecting rod bearings, and
crosshead shoes.
SPLASH LUBRICATION
➢Splash lubrication systems distribute lubricating oil by the splashing of the crank through the
lubricant surface in the pump.
➢Splash systems are used on small, horizontal, single-stage compressors with power demands up to
100 hp
PRESSURIZED LUBRICATION
➢The most common type of frame lubrication is the pressurized system.
➢Oil enters passages drilled into the crankshaft and flows through the main shaft and crank pin
bearings.

19. CYLINDER COOLING
• The Heat of compression and friction between the piston rings and the cylinder add heat to the cylinder.
Removing some of this heat is beneficial to the performance and reliability of the compressor by using
cooling system.
• Cylinder cooling reduces losses in capacity and power caused by suction gas preheating
• Cylinder cooling also promotes better lubrication for longer life and reduced maintenance
TYPES OF CYLINDER COOLING
1. AIR COOLED
In air cooled system, cooling fins provide a sufficient surface area to cool the cylinder by transferring
heat with atmosphere air.
2. THERMOSIPHON
The driving force for a thermosiphon derives from the change in density of the cooling fluid from the
hot to cold sections of the system. Discharge temperature below 99 ˚C is needed to use thermosiphon.
3. PRESSURIZED COOLING.
In locations where cooling water is not available, a self-contained, closed cooling fluid system may be
used. The system consists of a circulating pump, surge tank, and a fan-cooled radiator or air-to-liquid heat
exchanger.

20. CAPACITY CONTROL SYSTEM
TWO MAIN REASONS FOR COMPRESSOR CAPACITY REGULATION
➢Adjust the suction flow to match the process demand
➢Save energy
TYPES OF CCS
➢Speed variation
➢Clearance variation
➢Bypass system
➢valve removal
MODERN CCS
➢Stepless control system
➢Split range control system

21. PERFORMANCE FACTOR
SETTLING OUT PRESSURE
➢ The pressure of the compressor system when compressor is shutdown.
SUCTION PRESSURE
➢ Compression ratio inversely proportional to suction pressure.
SUCTION TEMPERATURE
➢ Cylinder capacity is inversely proportional to absolute suction temperature.
RATIO OF SPECIFIC HEATS(K)
➢ Volumetric efficiency directly proportional to K.
SPEED
➢ Cylinder capacity is directly proportional to compressor speed.

22. PERFORMANCE CURVE

23. APPLICATIONS
➢Automotive industry
➢Biogas plants
➢Chemical and petrochemical industry
➢Industrial gas manufacturing
➢Laboratory and research facilities
➢Food industry
➢Hydrogen filling stations

24. DIAPHRAGM COMPRESSOR
➢ The compression of gas occurs by means of a flexible membrane, instead of an intake element.
➢ The back and forth moving membrane is driven by a rod and a crankshaft mechanism. Only the
membrane and the compressor box come in touch with pumped gas. For this reason this
construction is the best suited for pumping toxic and explosive gases.
➢The membrane has to be reliable enough to take the strain of pumped gas. It must also have
adequate chemical properties and sufficient temperature resistance.

25. ROTARY COMPRESSOR
• Rotary compressor is a positive displacement machine used for gas
compression by reducing its volume.
TYPES OF ROTARY COMPRESSOR
➢Root Blower
➢Vane Type
➢Liquid Ring
➢Screw Compressor
➢Scroll Compressor

26. ROOT BLOWER
➢ The Roots type blower is a positive displacement compressor
which operates by pumping a fluid with a pair of lobes.
➢ Fluid is trapped in pockets surrounding the lobes and carried
from the intake side to the exhaust.
➢ The most common application of the Root type blower has
been as the induction device on two-stroke Diesel engines.
➢ Roots blowers are also used in reverse to measure the flow of
gases or liquids, for example, in gas meters
APPLICATIONS
➢ Waste water treatment
➢ Bio-gas recovery and re-circulation
➢ Soil hydrocarbon and solvent vapor extraction
➢ Drinking water purification
➢ Food, Beverage, and Pharmaceutical industries
➢ petrochemical industries

27. VANE TYPE ROTARY COMPRESSOR
➢The Vane type Air Compressor is having a fixed casing
and a rotary rotor disc which has slots for holding the
sliding plates as shown in the figure.
➢As the rotor rotates, the disc also rotates, thus allowing
the sliding plates to slide as the inner surface of the
casing is eccentric.
➢Thus the sliding plates moves away from the centre,
huge quantities of air will be trapped in, thus as the
plates converge, the air gets compressed and thus
results in compressed air.
APPLICATION
➢ Food and Beverage
➢ Dry Cleaning
➢ Pharmaceutical

28. LIQUID RING COMPRESSOR
• A liquid-ring compressor is a rotating positive-
displacement device that is very similar to a
rotary vane compressor
• It differs in having vanes that are an integral
part of the rotor that churn a rotating ring of
liquid to form the compression chamber seal.
APPLICATIONS
➢ Breathing air
➢ vent gas boosting/recovery
➢ Explosive gas boosting & chemical processes

29. SCREW COMPRESSOR
➢The screw compressors are efficient in low air
pressure requirements.
➢Two screws rotate with each other, thus trapping
air between the screws and the compressor
casing, forming pockets which progressively
travel and gets squeezed and delivering it at a
higher pressure which opens the delivery valve.
➢The compressed air delivery is continuous and
quiet in operation than a reciprocating
compressor.
APPLICATIONS
➢ process refrigeration
➢ Natural gas applications
➢ Fuel gas compression

30. SCROLL COMPRESSOR
➢The Scroll type compressors are having scrolls driven by the prime mover.
➢The scrolls outer edges trap air and then as they rotate, the air travel from outwards to inwards thus
getting compressed due to the reduction in the area.
➢Thus the compressed air is delivered through the central space of the scroll to the delivery air line.
APPLICATIONS
➢ food and fruit refrigeration
➢ truck transportation
➢ marine containers as well as residential and small
to medium scale commercial air-conditioning
applications.

31. DYNAMIC COMPRESSOR
• Dynamic compressor is a continuous-flow compressor which includes centrifugal compressor and
axial flow compressor.
• It is widely used in chemical and petroleum refinery industry for specifies services.
• They are also used in other industries such as the iron and steel industry, pipeline booster, and on
offshore platforms for reinjection compressors.
• The dynamic compressor is characterized by rotating impeller to add velocity and pressure to fluid.
TYPES
➢ Centrifugal compressor
➢ Axial flow compressor

32. CENTRIFUGAL COMPRESSOR
➢ The centrifugal compressor is well established for the compression of gases and vapours.
➢ It has proven its economy and uniqueness in many applications, particularly in which large volumes are
handled at medium pressures.
➢ A centrifugal compressor raises gas pressure by accelerating the gas as it flows radially out through the
impeller
➢ And converting this velocity energy to pressure by passage through a diffuser section.

33. TYPES OF MULTISTAGE CENTRIFUGAL COMPRESSOR
Straight-through (inline) centrifugal compressor cross section. Inline (compound) centrifugal compressor cross section.
➢ Inter cooling is not needed ➢ Inter cooling is needed

34. Back-to-back centrifugal compressor cross section. Dual-flow centrifugal compressor cross section.
➢ Inter cooling is needed
➢ Its used for high-flow/low-head
applications
➢ Inter cooling is needed

35. CASING
HORIZONTALLY SPLIT CASE
➢ A horizontally split case is split parallel to the axis of the
rotor.
➢ Access to the internals of the compressor for inspection
and maintenance is facilitated with this case design.
➢ The horizontally split design is inherently pressure-
limited to prevent gas leakage at the case split joint.
VERTICALLY SPLIT CASE
➢ This case is split perpendicular to the axis of the rotor.
➢ Heads (end covers) are installed at both ends for pressure
containment.
➢ The vertically split case configuration is capable of
handling higher pressures than the horizontally split type.

36. IMPELLER
➢ The impellers impart velocity to the gas with
blades that are attached to a rotating disc.
➢ An open impeller is used for high heads and
small-to-large-flow.
➢ A semi-enclosed impeller is used for large
flow.
➢ In an enclosed impeller, the gas is drawn into
the eye and flows out the edge or rim.
MOC
➢High-strength alloy steel
➢Stainless steel

37. TYPE OF IMPELLER ADVANTAGES DISADVANTAGES
Radial blades
➢ Reasonable compromise
between low energy transfer and high
absolute outlet
velocity
➢ No complex bending stress
➢ Ease in manufacturing
➢ Surge margin is narrow
Backward curved
blades
➢ Low outlet kinetic energy
➢ Low diffuser inlet Mach
number
➢ Surge margin is widest of Three
➢ Low energy transfer
➢ Complex bending stress
➢ Difficulty in Manufacturing
Forward curved
blades
➢ High energy transfer ➢ High outlet kinetic energy
➢ High diffuser inlet Mach
number
➢ Complex bending stress
➢ Difficulty in Manufacturing

38. DIFFUSER
The diffuser is an important part of the stationary flow path that
usually comprises two parallel walls forming a radial flow channel
➢ In the diffuser, the gas velocity decreases and dynamic pressure
is converted to static pressure.
➢ Return bend creates a 180-degree turn in the direction of flow
(i.e., from radially outward to radially inward).
➢ The diaphragms are usually made of cast iron or other hard
metal, like steel, and do not rotate with the shaft.
➢ Adjacent walls of the diaphragms form a passage called the
diffuser. After the gas travels through the diffuser, it enters the
return passage which guides it into the next impeller

39. TYPES OF SEALS
LABYRINTH SEALS
➢ Labyrinth type seals are used to Minimize recirculation losses within the
compressor
➢ A labyrinth seal consists of a number of teeth (knife-edges) that can be either
stationary or rotating.
➢ Sealing action is the result of flow resistance caused by repeated throttling across the
labyrinth teeth.
➢ The softer material yields on contact without damage to the harder material

40. LIQUID FILM SEALS
BRUSHING TYPE SEALS
➢ The bushing type is a very simple and rugged design that incorporates two adjacent
seal rings (bushings) at each end of the compressor.
➢ A sealing fluid is introduced into the space between the seal rings at a pressure
slightly above the process gas pressure inboard from the inner ring.
➢ For almost all centrifugal compressors equipped with liquid film seals, the sealing
fluid is the same light turbine oil as that used to lubricate the bearings.
MEACHANICAL CONTACT SEALS
➢ Mechanical contact seals employ a stationary carbon ring against a rotating seal
face. Oil is also used as the sealing medium in mechanical contact seals.
➢ The sealing oil is introduced by a pressure-regulating valve that is maintained at 25
to 40 psi above the seal reference pressure.
➢ One advantage of mechanical contact seals is a significantly reduced sour oil
leakage compared with the bushing design.

41. PERFORMANCE CURVE

42. SURGE CONDITIONS
➢ Surge is operating point , where maximum
head and minimum flow capacity is reached
STONEWALL POINT
➢ Stonewall is operating point, where low head and
high flowrate is reached
SETTLING OUT PRESSURE
➢ The pressure of the compressor system when
compressor is shutdown.

43. ANTI-SURGE CONTROL

44. CAPACITY CONTROL
SPEED VARIATION
• For a given discharge pressure, compressor capacity can be increased by merely increasing the speed of
rotation of impeller. Conversely, capacity may be decreased by reducing compressor speed.
• Capacity control by speed variation is the most effective way to maximize the operating flexibility of a
centrifugal compressor.
SUCTION THROTTLE VALVE
➢ When operating at lower capacities, the compressor inherently delivers a greater discharge pressure (for a
given process suction pressure) than desired. The solution to this problem is to install a throttle valve at the
inlet of the compressor.
➢ Suction pressure reduction by throttling increases the pressure ratio required to deliver a given discharge
pressure.
VARIABLE INLET GUIDE VANES
➢ When a system of variable inlet guide vanes is employed, it is possible to adjust the inlet guide vane angles to
maintain a desired discharge pressure over a range of capacity.
➢ For single stage compressors, this method of control is sometimes quite effective. However, for multistage
compressors, the range of control is less effective and becomes even less so with increasing numbers of
stages.

45. LOAD SHARING CONTROL
➢ Load sharing control is used to balance the load
to all compressors used in parallel.
➢ The aim is to prevent the compressor from
surging while other compressors are still far
from surging, also to increase efficiency.

46. APPLICATIONS
➢In gas turbines and auxiliary power units.
➢In automotive engine and diesel engine turbochargers and superchargers.
➢In pipeline compressors of natural gas to move the gas from the production site to
the consumer.
➢In oil refineries, natural gas processing, petrochemical and chemical plants.
➢Air-conditioning and refrigeration and HVAC: Centrifugal compressors quite
often supply the compression in water chillers cycles.

47. AXIAL FLOWCOMPRESSOR
• Axial compressor is a compressor that can
continuously pressurize gases.
• It is a rotating, airfoil-based compressor in which
the gas or working fluid principally flows parallel
to the axis of rotation, or axially.
• The energy level of the fluid increases as it flows
through the compressor due to the action of the
rotor blades which exert a torque on the fluid.
• Axial flow compressors are mainly used for
applications where the head required is low and
with the high intake volume of flow.
• The efficiency in an axial flow compressor is
higher than the centrifugal compressor.

48. COOLING SYSTEM
➢ The gas is cooled outside of the
compressor. Once the gas is cooled, it is
returned to the compressor
➢ the gas is cooled after it leaves the
compressor. The gas flows through the
aftercooler and on into the flow line.
Cooling is a crucial step in the compressed air process. The ideal gas law states that the pressure is directly
proportional to the temperature for any constant volume gas. so without cooling, the hot compressed air may
damage the equipment.

49. IMPERFECT INTERSTAGE COOLING

50. PERFECT INTERSTAGE COOLING

51. CONTROLS AND INSTRUMENTATION
➢ Flow control
➢ Speed control
➢ Suction throttle valves
➢ Anti surge control
➢ Flare valves
➢ Shutdown valves
➢ Blowdown valve
➢ Discharge check valve
➢ Relief valve
➢ Purge valve
➢ Discharge coolers
➢ Suction scrubbers
➢ Vent valve

52. PIPING AND INSTRUMENTATION DIAGRAM
LINK
COMPRESSOR DATA SHEETreciprocating compressor p&id.pdf

53. Summary of Typical Operating Characteristics of Compressors
From PIP REEC001 Compressor Selection Guidelines

54. TYPES OF
COMPRESSORS
ADVANTAGE DISADVANTAGE
Dynamic compressor
➢ Wide operating range
➢ High reliability
➢ Low maintenance
➢ Instability at reduced flow
➢ Sensitive to changes in gas composition
➢ Susceptible to rotor-dynamics problems
➢ Sensitive to liquids in the gas stream
Integrally Geared
Centrifugal
➢ Relatively inexpensive method of obtaining a
high compression ration
➢ High efficiency at best efficiency point
➢ Limited operating flow range
➢ High efficiency is limited to flow rates near the best
efficiency point
➢ Sensitive to liquids in the gas stream
Axial
➢ High capacity for a given size and high
efficiency
➢ Heavy duty and low maintenance
➢ Low compression ratios
➢ Limited turndown
Thermal/Jet
➢ No moving parts and low maintenance
➢ High pressure ratio
➢ Very low efficiency
➢ Narrow range of application

55. Positive Displacement
Compressors More tolerant to changes in gas composition than dynamic compressors.
Reciprocating (Piston)
➢ Wide pressure ratios
➢ High efficiency
➢ Heavy foundations required due to unbalanced forces
➢ Flow pulsation can cause vibration and structural
problems
➢ High maintenance compared to dynamic compressors
➢ Sensitive to liquids in the gas stream
Diaphragm
➢ Very high pressure
➢ Available in special materials
➢ No moving seals
➢ Low flow
➢ Limited capacity range
➢ Periodic replacement of diaphragms required
➢ Flow pulsation problems
Screw
➢ Wide range of applications
➢ Wet screw has high efficiency and high
pressure ratio
➢ Dry screw insensitive to changes in gas
composition and can handle dirty gases
➢ Noisy
➢ Wet screw not suitable for corrosive or dirty gases
Lobe
➢ Simple in design and construction
➢ Low cost
➢ Limited operating range and pressure ratio
➢ Capacity control limited to suction throttling

56. Sliding Vane
➢ Simple in design
➢ High single-stage pressure ratio
➢ Able to tolerate small quantities of liquids in the
process gas
➢ Generally unsuitable for process gases
➢ Low reliability
Liquid Ring
➢ High vacuum capability
➢ Able to tolerate small quantities of liquids in the
process gas
➢ High single-stage pressure ratio
➢ High reliability
➢ Sealing liquid/process gas compatibility required Sealing
liquid separation equipment required
➢ Limited suction pressure

57. COMPRESSOR DATASHEET
➢COMPRESSOR DATA SHEETcentrifugal compressor.pdf
➢COMPRESSOR DATA SHEETreciprocating compressor.pdf

58. BATTERY LIMIT
• DISCHARGE PRESSURE = 80 – 120 kg/cm2.gauge
• DISCHARGE TEMPERATURE = 50˚C
• STANDARD FLOWRATE = 15MMCFD

59. THANK YOU