Compressor
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Compressors & Compressed Air Systems
m
àraining Agenda: Compressor
Introduction àypes of compressors Assessment of compressors and compressed air systems Energy efficiency opportunities
Introduction Significant Inefficiencies á Compressors: 5 to > 50,000 hp á 70 ± 90% of compressed air is lost
Introduction Benefits of managed system á Electricity savings: 20 ± 50% á Maintenance reduced, downtime decreased, production increased and product quality improved
@ 6
Introduction Main Components in Compressed Air Systems á Intake air filters á Inter-stage coolers á After coolers á Air dryers á Moisture drain traps á Receivers
M 6
àraining Agenda: Compressor
Introduction àypes of compressors Assessment of compressors and compressed air systems Energy efficiency opportunities
Ô 6
àypes of Compressors àwo Basic Compressor àypes àype of compressor
Positive displacement
Reciprocating
Rotary
Dynamic
Centrifugal
Axial
À 6
àypes of Compressors Reciprocating Compressor á
sed for air and refrigerant compression
á
Works like a bicycle pump: cylinder volume reduces while pressure increases, with pulsating output
á
Many configurations available
á
Single acting when using one side of the piston, and double acting when using both sides
R
6
àypes of Compressors Rotary Compressor á Rotors instead of pistons: continuous discharge á Benefits: low cost, compact, low weight, easy to maintain á Sizes between 30 ± 200 hp á àypes á Lobe compressor á Screw compressor á Rotary vane / Slide vane
î
6
àypes of Compressors Centrifugal Compressor á Rotating impeller transfers energy to move air á Continuous duty á Designed oil free á High volume applications > 12,000 cfm
m 6
àypes of Compressors Comparison of Compressors á Efficiency at full, partial and no load á Noise level á Size á Oil carry-over á Vibration á Maintenance á Capacity á Pressure
mm 6
àraining Agenda: Compressor
Introduction àypes of compressors Assessment of compressors and compressed air systems Energy efficiency opportunities
m 6
Assessment of Compressors Capacity of a Compressor á Capacity: full rated volume of flow of compressed gas á Actual flow rate: free air delivery (FAD) á FAD reduced by ageing, poor maintenance, fouled heat exchanger and altitude á Energy loss: percentage deviation of FAD capacity m 6
Assessment of Compressors Simple Capacity Assessment Method á Isolate compressor and receiver and close receiver outlet á Empty the receiver and the pipeline from water á Start the compressor and activate the stopwatch á Note time taken to attain the normal operational pressure P2 (in the receiver) from initial pressure P1 á 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 à = àime take to build up pressure to P2 in minutes
m@ 6
Assessment of Compressors Compressor Efficiency á Most practical: specific power consumption (kW / volume flow rate) á Other methods á Isothermal á Volumetric á Adiabatic á Mechanical
mM 6
Assessment of Compressors Compressor Efficiency Isothermal efficiency Isothermal efficiency = Actual measured input power / Isothermal power
Isothermal power (kW) = P1 x Q1 x loger / 36.7
P1 = Absolute intake pressure kg / cm2 Q1 = Free air delivered m3 / hr r = Pressure ratio P2/P1
mÔ 6
Assessment of Compressors Compressor Efficiency Volumetric efficiency Volumetric efficiency = Free air delivered m3/min / Compressor displacement
Compressor displacement = Ȇ x D2/4 x L x S x Ȥ x n
D = Cylinder bore, meter L = Cylinder stroke, meter S = Compressor speed rpm Ȥ = 1 for single acting and 2 for double acting cylinders n = No. of cylinders
mÀ 6
Assessment of Compressors Leaks á Consequences á Energy waste: 20 ± 30% of output á Drop in system pressure á Shorter equipment life
á Common leakage areas á Couplings, hoses, tubes, fittings á Pressure regulators á Open condensate traps, shut-off valves á Pipe joints, disconnects, thread sealants
mR
6
Assessment of Compressors Leak Quantification Method á àotal leakage calculation: Leakage (%) = [(à x 100) / (à + t)] à = on-load time (minutes) t = off-load time (minutes)
á Well maintained system: less than 10% leakages mî 6
Assessment of Compressors Quantifying leaks on the shop floor á Shut off compressed air operated equipments á Run compressor to charge the system to set pressure of operation á Note the time taken for ³Load´ and ³nload´ cycles á Calculate quantity of leakage (previous slide) á If Q is actual free air supplied during trial (m3/min), then:
V â
6
Assessment of Compressors Example
6
6
6
! "
# !
$ ! "
%!
&' ( )
#
&' ($ )
#*
+ # # #* ,- % m 6
àraining Agenda: Compressor
Introduction àypes of compressors Assessment of compressors and compressed air systems Energy efficiency opportunities
6
Energy Efficiency Opportunities 1. Location á Significant influence on energy use
2. Elevation á Higher altitude = lower volumetric efficiency
6
Energy Efficiency Opportunities 3. Air Intake á Keep intake air free from contaminants, dust or moist á Keep intake air temperature low `
á Keep ambient temperature low when an intake air filter is located at the @ compressor 6
Energy Efficiency Opportunities 4. Pressure Drops in Air Filter á Install filter in cool location or draw air from cool location á Keep pressure drop across intake air filter to a minimum `
M 6
Energy Efficiency Opportunities 5. se Inter and After Coolers á Inlet air temperature rises at each stage of multi-stage machine á Inter coolers: heat exchangers that remove heat between stages á After coolers: reduce air temperature after final stage á se water at lower temperature: reduce power
Ô 6
Energy Efficiency Opportunities 6. Pressure Settings á Higher pressure á More power by compressors á Lower volumetric efficiency á Operating above operating pressures á Waste of energy á Excessive wear À 6
Energy Efficiency Opportunities 6. Pressure Settings 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
c. Segregating high/low pressure requirements Pressure reducing valves no longer needed
R 6
Energy Efficiency Opportunities 6. Pressure Settings d. Design for minimum pressure drop in the distribution line á
Pressure drop: reduction in air pressure from the compressor discharge to the point of use
á
Pressure drop < 10%
á
Pressure drops caused by á corrosion á inadequate sized piping, couplings hoses á choked filter elements
î 6
Energy Efficiency Opportunities 6. Pressure Settings d. Design for minimum pressure drop in the distribution line
àypical pressure drop in compressed air line for different pipe size ! " " !
6
Energy Efficiency Opportunities 7. Minimizing Leakage á
se ultrasonic acoustic detector
á
àighten joints and connections
á
Replace faulty equipment
8. Condensate Removal á
Condensate formed as after-cooler reduces discharge air temperature
á
Install condensate separator trap to remove condensate
m
6
Energy Efficiency Opportunities 9. Controlled usage á Do not use for low-pressure applications: agitation, combustion air, pneumatic conveying á se blowers instead
10. Compressor controls á Automatically turns off compressor when not needed 6
Energy Efficiency Opportunities 9. Maintenance Practices á Lubrication: Checked regularly á Air filters: Replaced regularly á Condensate traps: Ensure drainage á Air dryers: Inspect and replace filters
6
àraining Session on Energy Equipment
l
Compressors & Compressed Air Systems
àHANK YO FOR YOR AààENàION @ 6#$"%
Disclaimer and References
à
! "! !
#$% !
# ! ! ! # # ! &$%#'(()
à ! * +" , *
- . !/ M " ! 6
m
àraining Agenda: Compressor
Introduction àypes of compressors Assessment of compressors and compressed air systems Energy efficiency opportunities
Introduction Significant Inefficiencies á Compressors: 5 to > 50,000 hp á 70 ± 90% of compressed air is lost
Introduction Benefits of managed system á Electricity savings: 20 ± 50% á Maintenance reduced, downtime decreased, production increased and product quality improved
@ 6
Introduction Main Components in Compressed Air Systems á Intake air filters á Inter-stage coolers á After coolers á Air dryers á Moisture drain traps á Receivers
M 6
àraining Agenda: Compressor
Introduction àypes of compressors Assessment of compressors and compressed air systems Energy efficiency opportunities
Ô 6
àypes of Compressors àwo Basic Compressor àypes àype of compressor
Positive displacement
Reciprocating
Rotary
Dynamic
Centrifugal
Axial
À 6
àypes of Compressors Reciprocating Compressor á
sed for air and refrigerant compression
á
Works like a bicycle pump: cylinder volume reduces while pressure increases, with pulsating output
á
Many configurations available
á
Single acting when using one side of the piston, and double acting when using both sides
R
6
àypes of Compressors Rotary Compressor á Rotors instead of pistons: continuous discharge á Benefits: low cost, compact, low weight, easy to maintain á Sizes between 30 ± 200 hp á àypes á Lobe compressor á Screw compressor á Rotary vane / Slide vane
î
6
àypes of Compressors Centrifugal Compressor á Rotating impeller transfers energy to move air á Continuous duty á Designed oil free á High volume applications > 12,000 cfm
m 6
àypes of Compressors Comparison of Compressors á Efficiency at full, partial and no load á Noise level á Size á Oil carry-over á Vibration á Maintenance á Capacity á Pressure
mm 6
àraining Agenda: Compressor
Introduction àypes of compressors Assessment of compressors and compressed air systems Energy efficiency opportunities
m 6
Assessment of Compressors Capacity of a Compressor á Capacity: full rated volume of flow of compressed gas á Actual flow rate: free air delivery (FAD) á FAD reduced by ageing, poor maintenance, fouled heat exchanger and altitude á Energy loss: percentage deviation of FAD capacity m 6
Assessment of Compressors Simple Capacity Assessment Method á Isolate compressor and receiver and close receiver outlet á Empty the receiver and the pipeline from water á Start the compressor and activate the stopwatch á Note time taken to attain the normal operational pressure P2 (in the receiver) from initial pressure P1 á 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 à = àime take to build up pressure to P2 in minutes
m@ 6
Assessment of Compressors Compressor Efficiency á Most practical: specific power consumption (kW / volume flow rate) á Other methods á Isothermal á Volumetric á Adiabatic á Mechanical
mM 6
Assessment of Compressors Compressor Efficiency Isothermal efficiency Isothermal efficiency = Actual measured input power / Isothermal power
Isothermal power (kW) = P1 x Q1 x loger / 36.7
P1 = Absolute intake pressure kg / cm2 Q1 = Free air delivered m3 / hr r = Pressure ratio P2/P1
mÔ 6
Assessment of Compressors Compressor Efficiency Volumetric efficiency Volumetric efficiency = Free air delivered m3/min / Compressor displacement
Compressor displacement = Ȇ x D2/4 x L x S x Ȥ x n
D = Cylinder bore, meter L = Cylinder stroke, meter S = Compressor speed rpm Ȥ = 1 for single acting and 2 for double acting cylinders n = No. of cylinders
mÀ 6
Assessment of Compressors Leaks á Consequences á Energy waste: 20 ± 30% of output á Drop in system pressure á Shorter equipment life
á Common leakage areas á Couplings, hoses, tubes, fittings á Pressure regulators á Open condensate traps, shut-off valves á Pipe joints, disconnects, thread sealants
mR
6
Assessment of Compressors Leak Quantification Method á àotal leakage calculation: Leakage (%) = [(à x 100) / (à + t)] à = on-load time (minutes) t = off-load time (minutes)
á Well maintained system: less than 10% leakages mî 6
Assessment of Compressors Quantifying leaks on the shop floor á Shut off compressed air operated equipments á Run compressor to charge the system to set pressure of operation á Note the time taken for ³Load´ and ³nload´ cycles á Calculate quantity of leakage (previous slide) á If Q is actual free air supplied during trial (m3/min), then:
V â
6
Assessment of Compressors Example
6
6
6
! "
# !
$ ! "
%!
&' ( )
#
&' ($ )
#*
+ # # #* ,- % m 6
àraining Agenda: Compressor
Introduction àypes of compressors Assessment of compressors and compressed air systems Energy efficiency opportunities
6
Energy Efficiency Opportunities 1. Location á Significant influence on energy use
2. Elevation á Higher altitude = lower volumetric efficiency
6
Energy Efficiency Opportunities 3. Air Intake á Keep intake air free from contaminants, dust or moist á Keep intake air temperature low `
á Keep ambient temperature low when an intake air filter is located at the @ compressor 6
Energy Efficiency Opportunities 4. Pressure Drops in Air Filter á Install filter in cool location or draw air from cool location á Keep pressure drop across intake air filter to a minimum `
M 6
Energy Efficiency Opportunities 5. se Inter and After Coolers á Inlet air temperature rises at each stage of multi-stage machine á Inter coolers: heat exchangers that remove heat between stages á After coolers: reduce air temperature after final stage á se water at lower temperature: reduce power
Ô 6
Energy Efficiency Opportunities 6. Pressure Settings á Higher pressure á More power by compressors á Lower volumetric efficiency á Operating above operating pressures á Waste of energy á Excessive wear À 6
Energy Efficiency Opportunities 6. Pressure Settings 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
c. Segregating high/low pressure requirements Pressure reducing valves no longer needed
R 6
Energy Efficiency Opportunities 6. Pressure Settings d. Design for minimum pressure drop in the distribution line á
Pressure drop: reduction in air pressure from the compressor discharge to the point of use
á
Pressure drop < 10%
á
Pressure drops caused by á corrosion á inadequate sized piping, couplings hoses á choked filter elements
î 6
Energy Efficiency Opportunities 6. Pressure Settings d. Design for minimum pressure drop in the distribution line
àypical pressure drop in compressed air line for different pipe size ! " " !
6
Energy Efficiency Opportunities 7. Minimizing Leakage á
se ultrasonic acoustic detector
á
àighten joints and connections
á
Replace faulty equipment
8. Condensate Removal á
Condensate formed as after-cooler reduces discharge air temperature
á
Install condensate separator trap to remove condensate
m
6
Energy Efficiency Opportunities 9. Controlled usage á Do not use for low-pressure applications: agitation, combustion air, pneumatic conveying á se blowers instead
10. Compressor controls á Automatically turns off compressor when not needed 6
Energy Efficiency Opportunities 9. Maintenance Practices á Lubrication: Checked regularly á Air filters: Replaced regularly á Condensate traps: Ensure drainage á Air dryers: Inspect and replace filters
6
àraining Session on Energy Equipment
l
Compressors & Compressed Air Systems
àHANK YO FOR YOR AààENàION @ 6#$"%
Disclaimer and References
à
! "! !
#$% !
# ! ! ! # # ! &$%#'(()
à ! * +" , *
- . !/ M " ! 6
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