This document provides an overview of compressed air systems and opportunities for improving energy efficiency. It discusses types of compressors, how to assess compressor performance and leaks, and identifies several areas where energy efficiency can be improved, including installing intercoolers and aftercoolers, minimizing pressure drops and leakage, optimizing pressure settings, improved condensate removal, and implementing control strategies and maintenance practices. The overall message is that significant electricity savings of 20-50% are possible from a well-managed compressed air system with reduced pressure drops, leaks, and operating pressures.

1. Compressed air supply
-- Dr Nisar Ahmed Arain
-- Assistant Professor
--Anesthesia/Critical care/ER

2. 2
© UNEP 2006
--Training Agenda and Compressor
--Introduction
--Types of Compressors
--Assesment of Compressors
and compressed air system
--Energy efficiency opportunities

3. Compressors:5to>
50,000hp
70– 90%ofcompressedairislost
--INTRODUCTION
--Significant Inefficiencies

4. INTRODUCTION
--BENEFITS OF MANAGED SYSTEM
--Electricity Savings: 20—50%
--Maintenance reduced
--Downtime decreased
--Production increased and
--Product quality improved

5. Introduction
Main Components in
Compressed Air System
--Intake Air Filters
--Inter Stage
--Coolers After Coolers
--Coolers
--Air Dryers
--Moisture drain traps
--Receivers

6. -Training Agenda Compressor
--Introduction
--Types of Compressors
--Assesment of Compressors
and compressed air systems
--Energy efficiency opportunities

7. Typeof
compressor
Positive
displacement
Dynamic
Reciprocating Rotary Centrifugal Axial
-Types of Compressors
-Two Basic Compressor Types

8. -Types of Compressors
-Reciprocating Compressor
--Used for air and refrigerant Compression
--Works like a bicycle Pump: Cylinder volume
reduces while pressure increases with
pulsating output
--Many configurations are available
--Single acting when using one side of the piston
and double acting when using both sides

9. -Types of Compressors
-ROTATORY COMPRESSORS
--Rotators instead of Pistons: continuous discharge
--Benefits of Low cost, Compact, low weight, easy
to maintain sizes between 30 to 200 hp
--TYPES
--Lobe Compressor
--Screw compressor
--Rotatory Vane/Slide Vane

10. -Types of Compressors
-Centrifugal Compressor
--Rotating impeller transfers energy
to move air continuous duty
--Designed oil free High Volume
applications >12,000 cfm

11. - Types of Compressors
-Comparison of Compressors
--Efficiency at full, partial and no load
--Noise level
--Size
--Oil Carry-over
--Vibration
--Maintenance
--Capacity
--Pressure

12. -Training Agenda Compressor
--Introduction
--Types of Compressors
--Assesment of Compressors and
compressed air system
--Energy efficiency opportunity

13. --Assesment of Compressors
--Capacity of a Compressor
--Capacity:-Full rated volume of flow of
compressed gas
--Actual Flow Rate:-Free air delivery(FAD)
--FAD:- reduces by ageing, Poor Maintenance
and Fouled heat exchanger and altitude
--Energy Loss:-Percentage deviation of FAD
Capacity

14. --Assesment of Compressors
--Simple Capacity Assesment Method
--Isolate compressor and receiver and close receiver outlet
--Empty the receiver and the pipeline from water
--Start the compressor and activate the stop watch
--Note time taken to attain the normal operational pressure
P2(In the receiver)from initial pressure P1
Calculate the capacity FAD
--P2=Final Pressure after filling
(Kg/cm2a)
--P1=Initial Pressure(Kg/cm2a)
after bleeding)
--P0=Atmospheric pressure
(Kg/cm2a)
--V=Storage volume in m3 which
includes receiver, after cooler
and delivery piping
--T=Time taken to build up
pressure to P2 in minutes

15. --Assesment of Compressors
--Compressor Efficiency
--Most practical specific power consumption
(KW/Volume flow rate)
--Other methods
a-Isothermia-1
b-Volumatric
c-Adiabatic
d-Mechenical

16. -Assesment of Compressors
-Compressor Efficiency
-Isothermal efficiency
--Isothermal efficiency=Actual measured input power
per Isothermal power
--Isothermal power(KW)=P1 x Q1 x logger / 36.7-P1=
Absolute intake pressure Kg Per cm2
--Q1=Free air delivered m3 per hr
--r=Pressure ratio P2/P1s

17. -Assesment of Compressors
-Compressor Efficiency
-Volumetric efficiency
--Volumetric efficiency=Free air
delivered/compressor displacement
--Compressor displacement=ΠxD2/4xL xS xχ x
n-D=Cylinderbore,meterL=Cylinderbore,
meterL=Cylinderstroke,meterS=compressor
speedrpmX =1forsingleactingand2for
doubleactingcylindersn=No.ofcylinders

18. -Assesment of Compressors
-Leaks
--consequences
--Energy waste: 20 – 30% of output
--Drop in the system pressure
--shorter equipment life
--Common leakage areas
--Couplings, hoses, tubes, fittings
--Pressure regulators
--Open condensate traps, shut off valve
--Pipe joints, disconnects, thread sealants

19. -Assesment of Compressors
-Leak Qualification Method
-Total Leakage Calculation
--Leakage (%) = [(Tx100)/(T +
t)]
--T=On load time(minutes)
t=off load time (Minutes)
--well maintained system: less than 10%
leakages

20. -Assesment of Compressors
-Quantifying leaks on the shop floor
--Shut off compressed air operated equipment's run compressor
to charge the system to set pressure of operation
--Note the time taken for “Load” and “Unload” cycles calculate
quantity of leakage (previous slide)
If Q is actual free air supplied during trial
(m3/min) then
system leakage (m3/minute) = Q X T (T + t)

21. ---Compressor capacity (m3/minute) = 35
---Cut in pressure, kg/cm2 = 6.8
---Cut out pressure, kg/cm2 = 7.5
---Load kW drawn = 188
kW
---Unload kW drawn = 54
kW
---Average ‘Load’ time =1.5
min
---Average ‘Unload’ time
-Assesment of Compressors
--EXAMPLE

22. -Raining Agenda: Compressor
--Introduction
--Types of compressors
--Assesment of compressors
and compressed air systems
--Energy efficiency
opportunities

23. -Energy Efficiency Opportunities
1-Location
significant influence on energy use
2-Elevation
Higher altitude = lower volumetric efficiency

24. -Energy Efficiency Opportunity
3. Air Intake
--Keep intake air free from contaminants, dust
or moist Keep intake air temperature low
--Every 4oC rise in inlet air Temperature = 1%
higher
energy consumption
--Keep ambient temperature low when an intake
air
filter is located at the compressor

25. -Energy Efficiency Opportunities
4. Pressure Drops in air Filter
--Install filter in cool location or draw air from
cool places
--Keep pressure drop across intake air filter
to a minimum
--Every 250 mm WC pressure drop =
2% higher energy consumption

26. -Energy Efficiency Opportunities
-5. Use Inter and After coolers
--Inlet air temperature rises at each stage of
multistage machine
--Inter coolers: heat exchangers that remove heat
between stages
--After coolers: reduce air temperature after final
stage
--Use water at low temperature: reduce power

27. -Energy Efficiency Opportunities
6.Pressure Settings
-Higher Pressure
a-More power by compressors
b-Lower volumetric efficiency
-Operating above operating pressures
a-Waste of energy
b-Excessive wear

28. Energy Efficiency Opportunities
6.Pressure setting cont.
--a-Reducing delivery pressure operating a compressor
at 120 PSIG instead of 100 PSIG: 10% less energy
and reduced leakage rate
--b-Compressor modulation by optimum pressure
settings, Applicable when different compressors
connected Segregating high/Low pressure
requirements
Pressure reducing valves no longer needed

29. -Energy Efficiency Opportunities
6-Pressure Settings cont.
--Design for minimum pressure drop in the distribution line
--Pressure drop: reduction in air pressure from the
compressor discharge to the point of use
--Pressure drop less then 10%
--Pressure drop caused by
a-corrosion
b-Inadequate sized piping couplings hoses
c-checked filter elements inadequate sized

30. 3
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© UNEP 2006
-- Energy Efficiency Opportunities
--6-Pressure settings cont.
--Design for minimum pressure drop in the
distribution line
--Different pipe size
--Typical pressure drop in compressed air line

31. -Energy Efficiency Opportunities
7-Minimizing Leakage
--Use ultrasonic acoustic detector
tighten joints and connections
replace faulty equipment
8-Condensate Removal
--Condensate formed as after cooler
reduces discharge air temperature
--Install condensate separator trap to
remove condensate

32. -- Energy Efficiency Opportunities
9-Controlled Usage
--Do not use for low pressure applications
agitation, combustion air, Pneumatic
conveying use blowers instead
10-Compressor Controls
--Automatically terns off compressor when
not needed

33. Energy Efficiency Opportunities
9-Maintainence Practices
--Lubrication:- checked regularly
--Air Filters:-Replaced regularly
--Condensate Traps:-Ensure drainage
--Air dryers:-Inspect and replace filters

34. THANK YOU