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GMRC Eng ine Ana ly zer & Re l iab i l i t y W or k shopNashville, TN
July 27-29, 2011
COMPRESSOR EMI SSI ONS
TECHNOLOGY REVI EW
Cra ig Mar t inApplications Engineering Supervisor
Aleksey Dubrov enskyProject Engineer
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Pot en t ia l Leak Po in t s
Oil WiperPacking
Packing CaseNose Gasket
Between Packing Case Cups
Distance PieceVent/Drain
Outer Head
Gasket
Valve CoverGasket
Valve UnloaderPacking
Packing Case Vent
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Pack in g Leak age Fact or s
Failure to account for em issions escap ing in t o t hed is t ance p iece may result in underestimation of
packing related emissions by up to 4 0 % .- U.S. EPA Natural Gas STAR Reducing Methane Emissions From Compressor Rod
Packing Systems, July 2003
+ + + + + =LEAKAGE AT
FRAMEBREATHER
LEAKAGE AT
SECONDARYDISTANCEPIECE VENT
LEAKAGE AT
DISTANCEPIECE DRAIN
LEAKAGE AT
DISTANCEPIECE VENT
LEAKAGE AT
PACKING CASE
LEAKAGE AT
VALVEUNLOADERPACKING
TOTALLEAKAGE
SECONDARY DISTANCEPIECE DRAIN
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New Em issions Regu lat ions
EPA: Best Available Measurement Methods must beused to measure all greenhouse gas (GHG) emissions
Required by July 31st or September 30th, 2011
Petroleum & Natural Gas Systems of the Greenhouse Reporting Rule:Subpart W (40 CFR Parts 98)
EPA defines GHG as any gas that absorbs infraredradiation
Water vapor
CH4
N2O
CFCs
SF6
CO2 HCFCs
HFCs
PFCs
1
Source: EPA Climate Change Directory http://www.epa.gov/climatechange/index.html1
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For ces Dr iv in g Em ission s Redu ct ion s
New emissions regulations
Currently limited to emissions measurement
Possibly future cap-and-trade restrictions on emissions
Economics
Lost production is very costly
Payback on upgrades typically less than one year
Reliability Increase lifecycle of equipment
Operating efficiency becoming a competitive necessity
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Em ission s Man agem ent
Vapor Recovery System
Channel emissions back to a controlled source
Can be expensive and complicated
Modify Existing Packing Case to Reduce Leakage WAT ring used to restrict gas flow into the vent
Field testing confirms low leakage
Additional frictional heat loading on piston rod
Application temperatures should be reviewed
Low-Friction Seal Technology
Low Leak Packing Technology
Possibly able to utilize existing cases Documented results from years of field applications
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WAT Ring
Side-loaded ring, single-acting
Seals well at low pressures
Vent Rin gs
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Tr ad i t ion a l Pack in g Seal Rin gs
Basic functionality of a single-acting seal ring:
During discharge stroke, high pressure gas enterspacking case
Pressure loads ring against sealing surfaces
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Traditional setup
Several seal rings
Standard vent seal
Outdated design
St an dar d Pr essu r e Pack in g
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Low Leak Pack in g Tech n o log y
More effective seals
Fewer rings required
Years of documented field results
Near-zero leakage
Longer packing life
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Seal Rin gs
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Seal Rin gs
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Seal Rin gs
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Seal Rin gs
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100
150
200
250
300
350
0 500 1000 1500 2000 2500 3000 3500
DISCHARGE PRESSURE ~ PSI
RODTEMPERATURE~F
Conventional Packing
Low Leak Technology
Pist on Rod Tem per a t u r e
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WAT Ring
Side-loaded ring, single-acting
Seals well at low pressures
Vent Rin gs
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Ven t Seal Rin gs
Vent Seal RingUpstream of Vent
Typical Low LeakPacking Design
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Pist on Rod Tem per a t u r e:
Vent -Seal Ring Ups t r eam o f Ven t Cu p
0
100
200
300
400
Standard Packing Vent Seal Ring Upstreamof Vent Cup
Tempera
ture(F)
Test 1
Test 2Test 3
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Low - Fr ict ion Seal Tech n o log y
Restricts gas flow into the vent
Reduced frictional heat on piston rod
Friction causes increased piston rod temperatures
Increased leakage rates
Decreased packing lifespan
Controls leakage in standby mode
Confirmed field and lab results
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FI ELD DATA
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Static cylinders can resultin significant leakage Cylinder 1 8.93 SCFM
$38,675 / yr (based on$8 / decatherm)
* Year based on8,760 run hours
Std. BronzeLow Leak
Low Leak
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It is possible to obtain lowrates (~0.1 SCFM) in
running conditions.
Leak rates are below 0.1
SCFM
* Year based on8,760 run hours
Low Leak
Low LeakStd. Bronze
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A small number of cylinderscan cause a large amount of
the total leakage.
96% of the total packing leakagecomes from Cylinder 1 24
SCFM - ~$100K / yr!
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Distance Piece leakage cancontribute a significant amount
to the total leakage.
23% of the total leakageis coming from thedistance piece vent
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Unknown packing and Low Leak packing maintained
low leak rates. Standard bronze packing hasdeveloped a moderate leak at 12,900 hours.
Std.
Low Leak =
Low Leak =
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Cu m u la t i ve Leak age Com par ison
The area under the curve represents the totalleakage throughout the life of the packing
STANDARD
UpgradedPacking Case
Low LeakTechnology
Standard PackingSeal Rings
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STANDARD
Cu m u la t i ve Leak age Com par ison
The area under the curve represents the totalleakage throughout the life of the packing
UpgradedPacking Case
Low LeakTechnology
Standard PackingSeal Rings
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STANDARD
Cu m u la t i ve Leak age Com par ison
The area under the curve represents the totalleakage throughout the life of the packing
UpgradedPacking Case
Low LeakTechnology
Standard PackingSeal Rings
Jus t i f i ca t ionfo r Pack in g
Rep lacement
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Packing case maintenance
Upgrade nose gasket to a spiral wound gasket
Replace existing BD vent rings to a WAT
Lap cups 4 light bands flatness
Verify parallelism of cup faces
Within .001
Verify cup depths & ring clearances Verify rod surface finish
8-12 Ra for induction-hardened rod
6-8 Ra for TC-coated or nitrided rod
Verify packing case alignment Ensure proper bolt tightening procedures
Best Pr act ices
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CASE STUDI ES
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Case St u d y I
Measured packing vent flow
Two identical H2 machines
Five-throw Worthington BDCs
Utilized thermal mass flow meterto gather emissions data
Provided options for emissions
measurement
Permanent installation
Portable installation
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Resul ts
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Case St u dy I I
24 cylinders
Standard packing
Measured packing vent leakage on-site
Changed all cases over to Low Leak technology
Measured leakage after upgrades
Below measurable range of flow meter
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Leak age Com par ison ( SCFM)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Low Leak StandardLeakage
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OTHER EMI SSI ONS
SOURCES
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Dr esser Ran d KVR Un loader
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Before After
Air Cylinder
Rope Packing
Seal
Cartridge
Plug
Actuator Rod
Indicator Pin
Up gr ade t o Seal Car t r idg e
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Com pr essor Va lve
Un load er & Act u at o r
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Jack Bo l t St y le Ret a iner s
Poor sealingaround the jack
bolt results infugitiveemissions, whichcan be hazardous
to people and theenvironment
Potential Leak
Hi h S h R i
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High St r en g t h Ret a in er
Replace the single jam nutwith a multiple jam nutdesign
O-ring around the cagejack bolt provide superiorsealing
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Th an k You !