by ELGI EQ UIPMEN TS LTD New Trends in Design and Application Aspects of Compressors Contents ELGI – capability & reach Need for Energy efficiency Energy efficiency in design § Efficiency relat ed terms § Sizing & Staging § Component selection § Manufacturing process Energy efficiency in application § Selecting the type of compressor § Maintenance & application engineering Elgi completed its 50 th year on 14 th March 2010 Sales Turnover-5810 Million Employees- More than1200 Global presence in over 60 countries • One of the few companies in the world to design and manufacture rotors and airends • State-of-the-art Horizontal, Vertical and CNC Machining Centers Capability In China Wholly-owned subsidiary with assembly plant In Middle East Wholly-owned subsidiary with warehouse facility In Brazil Wholly-owned subsidiary with warehouse facility In Europe Acquired BELAIR of France, a company engaged in assembly, sales and service of industrial compressors and accessories. Global footprint ELGI fact or y in Chi na • Exports contribute to 20% of overall sales • Expanding footprint in 63 countries with wide product range and deep reach • Larger distribution network • Well trained sales and service engineers • Footprint in 63 countries Reach Contents
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year on 14 March 2010 Capability - CIIGBC€¦ · ØELGI – capability & reach ... efficiency • Size of the compressor to match the above guide lines Energy efficiency in Sizing
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by
ELGI EQ UIPMENTS LTD
New Trends in Design and Application Aspects of Compressors
Contents
Ø ELGI – capability & reach
Ø Need for Energy efficiency
Ø Energy efficiency in design
§ Efficiency relat ed terms
§ Sizing & Staging
§ Component selection
§ Manufacturing process
Ø Energy efficiency in application
§ Selecting the type of compressor
§ Maintenance & application engineering
Elgi completed its 50th year on 14th March 2010
Sales Turnover-5810 Million
Employees- More than1200
Global presence in over 60 countries
• One of the few companies in the world to design and manufacture rotors and airends
• State-of-the-art Horizontal, Vertical and CNC Machining Centers
Capability
In ChinaWholly-owned subsidiary with assembly plant
In Middle EastWholly-owned subsidiary with warehouse facility
In BrazilWholly-owned subsidiary with warehouse facility
In EuropeAcquired BELAIR of France, a company engaged in assembly, sales and serviceof industrial compressors and accessories.
Global footprint
ELGI factor y in Chi na
• Exports contribute to 20% of overall sales
• Expanding footprint in 63 countries with wide product range and deep reach
• Larger distribution network
• Well trained sales and service engineers
• Footprint in 63 countries
Reach
Contents
Energy efficiency in compressed air systems:
• 10 to 20% of power consumed is for production of compressed air
• It’s the most expensive energy available to us (8 times more expensive than electricity)
Energy efficiency in compressed air systems: Statistics indicate that
Ø The typical compressed air system uses only 50% of its air supply for production, the
rest is wasted or lost to air leaks
Energy efficiency in compressed air systems:
Ø In the cost of compressed air, approximately 76% is constituted by electricity /fuel cost
Assumptions in this example include a 75 HP compressor operated 2 shift a day 5 days a week at an aggregate electric rate of Rs. 4.5 / kWh over 10 year of equipment life
Typical Lifetime Compressed Air Costs in perspective –Costs Over 10 years
Energy efficiency in compressed air systems:
Contents
Energy efficiency in Design
Efficiency related terms
• Free Air Delivery: Actual Volume of the air delivered by the compressor within a unit
time calculated at inlet conditions. Units: m3/hr, m3/min, cfm
• Shaft Power: Actual power consumed by the compressor to compress a given volume of
air from inlet pressure to out let pressure. This includes the volumetric and mechanical
losses inside the airend. Units: kW, hp
• Volumetric efficiency: Ratio of Actual capacity (FAD) of the compressor to swept
• Adiabatic efficiency: Ratio of the actual power to the adiabatic power
•adiabatic = Adiabatic power / Actual power
• Specific Power consumption : Shaft power consumed for an unit volume of flow
delivered, Unit:kW/m3/minContents
Energy efficiency in Sizing :
Leakages : Air flowing back through the clearance volumes. Potential & Inherent source of ineffi ciency
• The clearance volumes are inevitable
• For a given size they need to be optimized
• By optimal sizing the leakages can be reduced
A screw compressor example….
Energy efficiency in Sizing :
A screw compressor
Optimizing Clearances that Affect Performance
• Discharge end clearance (60%) : The clearance between the end face of the rotor and the
Bearing housing
• Inter lobe Clearance (30%) : The clearance between the lobes of the male and female
rotor
• Rotor Tip Clearance (10%) : The clearance between the rotor housing and the male or
female rotor tip
Energy efficiency in Design
In design the focus is to get maximum flow at a given power
• Sizing / Staging
1. Size of the compressor
2. Speed of the compressor
3. Number of stages
Variation of Volumetric Efficiency and Isentropic Efficiency with RPM
0.75
0.8
0.85
0.9
0 1000 2000 3000 4000 5000 6000 7000
Male Rotor Speed (RPM)
Effic
ienc
y, %
Volumetric EfficiencyIsentropic Efficiency
• Recommended tip speed range 10 – 40 m/sec• Minimum & Maximum flow to be positioned in that range• Design point at the optimum value of both volumetric efficiency and isentropic
efficiency• Size of the compressor to match the above guide lines
Energy efficiency in Sizing
Variation of Specific Power for different sizes of compressors
6.000
6.200
6.400
6.600
6.800
7.000
7.200
7.400
7.600
7.800
8.000
5 10 15 20 25 30 35 40TIP SPEED (m/s)
SPEC
IFIC
PO
WER
(kW
/m3/
min
)
5373102
Energy efficiency in Sizing
Thus for the same flow selecting a higher size within the guidelines of tip speed will have a higher energy
efficiency. Volumetric efficiency increases linearly with increase in size, as the displacement linearly
increases with size, but the clearances do not
Single Stage and Two Stage Compressors
• In single stage compressor, the discharge pressure required is achieved in one stage,
where as in two stage compressors, it is achieved in two stages.
• Two stage compressors are preferred over single stage due to Energy benefit or for
high pressure applications
Two stage Compressors for Energy benefit
• Inter Cooling.
• Divided Pressure Ratio
Energy efficiency in Staging
Two stage Compressors for Energy benefit
• abcd single stage
• abefgd two-stage with inter cooling
•• Area under PV diagram is work
Energy efficiency in Staging
Contents
Energy Efficiency in system component selection
Sources of energy loss in a system:• Electrical equipment• Pressure drop across the system• Friction
Electrical equipment• Main motor - Super efficiency motors, permanent magnet motors, Eff1 replacing Eff2 motors• Fan motor - Eff1 instead of Eff2 & efficient solutions like use of plastic fan, fan controlled by a
thermal switch
Pressure drop across the system
• Suction pressure drop - Whatever lost in the suction is lost forever. Components like air filter and suction valve should be appropriately sized
• Discharge pressure drop - Pressure drop in down stream components results in higher shaft power consumption
It is a good practice to have indicators across the above components in the system to indicate the pressure drop
• For example the recommended accessories for various sizes of compressors is shown in table 1
MODEL 53 73 102 159 159 S 225 284
Power4 & 5.5
kW5.5 – 11
kW11 – 22
kW30 – 37
kW45 – 55
kW55 – 75
kW55 – 75
kW90 –
160 kW160 kW
Intake Valve Size 1.5” 1.75” 2.5” 3” 4” 4” 6” 6”
Oil Injection Orifice** 6 mm 4 mm 12 mm 10 mm 10 mm 15 mm 22 mm
Discharge Pipe Size (mm) 16 NB 32 NB 40 NB 65 NB 80 NB 80 NB 80 NB
Equivalent Discharge Pipe Size as per ASTM A
106 in inches- 1.25” 1.5” 2.5” 3” 3” 3”
Return Line Orifice 0.5 mm 0.8 mm 0.8 mm 1.5 mm1.57 mm