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Reciprocating Compressor Seals Partner Savings From Compressor Rod Packing. Presented to 2005 EPA Star Conference - Midland June 8, 2005 Jim Rauh, Compressor Engineering Rick Loveless, Northern Natural Gas. Engine and Compressor. Discussion Points. Standard packing cases How packing works
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Reciprocating Compressor Seals Partner Savings From Compressor Rod Packing Presented to 2005 EPA Star Conference - Midland June 8, 2005 Jim Rauh, Compressor Engineering Rick Loveless, Northern Natural Gas
Discussion Points • Standard packing cases • How packing works • Impediments to proper sealing • Packing case leaks • Northern Natural case histories • Low Emission Packing (LEP) • Summary/Q and A
Ways packing case can leak Nose gasket (no crush) Packing to rod (surface finish) Packing to cup (lapped surface) Packing to packing (dirt/lube) Cup to cup (out of tolerance) What makes packing leak? Dirt or foreign matter (trash) Worn rod (.0015”/per inch dia.) Insufficient/too much lubrication Packing cup out of tolerance (+.002”/-.000”) Improper break-in on startup Liquids (dilutes oil) Incorrect packing installed (backward or wrong type/style) Impediments to Proper Sealing
Leakage Rates • Packing is designed to restrict leakage • Fugitive natural gas emissions result in significant loss of revenue/greenhouse gas • Average rod leak rate is .98 to 1.86 scfm (28-53 liters/minute) based on Pipeline Research Committee findings
Northern Natural/CECO Historical Data on Units A/B • Monitored emission units are methane leakage in liters/minute for two locations • Testing is still in progress, current 3 months leak rate shows zero leakage • Unit A leakage as high as 301 liters/min • Unit B leakage as high as 105 liters/min
NNG Packing Leakage Economic Replacement Point • Approximate packing replacement cost is $3000 per compressor rod (parts/labor) • Assuming gas at $5/MCF: 1CFM=28.316L • 50 liters per min/28.316=1.766 scfm • 1.766 x 1440min/day=2543 scf per day • 2543/1000=2.543 MCF • 2.543 x 365 days= 928MCF per year • 928 x $5MCF=$4640 per year leakage
Here Is the Solution • Low emission packing (LEP) overcomes low pressure to prevent leakage. • The side load eliminates clearance and maintains positive seal on cup face. • LEP is a static seal, not a dynamic seal. No pressure is required to activate the packing. • This design works in existing packing case with limited to no modifications required.
Reasons to Use LEP • Upgrade is very inexpensive. • Significant cost savings and reduction of greenhouse gas are major benefit. • Refining, petrochemical and air separation plants have used this design for many years to minimize fugitive emissions. • Should the natural gas industry follow suit?
What’s in Your Packing Case? • Consult with operations to verify your current packing case configuration. • What are the current leak rates? • Typical LEP conversion is around $125 and with gas at $6 MSCF, packing case leakage should be identified and fixed. • Monitoring emissions reduces greenhouse gas release.
Summary • Packing is a dynamic seal designed to restrict leakage. • Verify your current leakage rate. • Low Emission Packing (LEP) is an inexpensive conversion to reduce fugitive emissions.
Questions? Thank you!