Pressure Packing Presentation

8/13/2019 Pressure Packing Presentation

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Reciprocating Compressor SealsPartner Savings From

Compressor Rod Packing

Presented to2005 EPA Star Conference - Midland

June 8, 2005

Jim Rauh, Compressor EngineeringRick Loveless, Northern Natural Gas


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Engine and Compressor


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Discussion Points

Standard packing casesHow packing works

Impediments to proper sealingPacking case leaks

Northern Natural case histories

Low Emission Packing (LEP)Summary/Q and A


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Compressor Cylinder Cut Away


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Standard Packing Case


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Pressure Activates Packing


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Impediments to Proper SealingWays packing case can leak

Nose gasket (no crush)Packing to rod (surfacefinish)Packing to cup (lappedsurface)Packing to packing(dirt/lube)Cup to cup (out oftolerance)

What makes packing leak?Dirt or foreign matter (trash)Worn rod (.0015/per inch dia.)

Insufficient/too much lubricationPacking cup out of tolerance(+.002/ -.000) Improper break-in on startup

Liquids (dilutes oil)Incorrect packing installed(backward or wrong type/style)


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Typical Packing Leak Paths


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Leakage Rates

Packing is designed to restrict leakageFugitive natural gas emissions result in

significant loss of revenue/greenhouse gasAverage rod leak rate is .98 to 1.86 scfm(28-53 liters/minute) based on PipelineResearch Committee findings


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Northern Natural/CECOHistorical Data on Units A/B

Monitored emission units are methaneleakage in liters/minute for two locations

Testing is still in progress, current 3 monthsleak rate shows zero leakageUnit A leakage as high as 301 liters/min

Unit B leakage as high as 105 liters/min


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NNG Unit A/B Leakage Rates

0

50

100

150

200

250

300

350

1997 1998 1999 2000 2001 2002 2003 2004 2005 LEP

Unit A

Unit B


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NNG Packing LeakageEconomic 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


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Here Is the Solution

Low emission packing (LEP) overcomeslow pressure to prevent leakage.

The side load eliminates clearance andmaintains 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 casewith limited to no modifications required.


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LEP Packing Configuration


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Orientation in Cup


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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 yearsto minimize fugitive emissions.Should the natural gas industry follow suit?


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Whats in Your Packing Case?

Consult with operations to verify yourcurrent packing case configuration.

What are the current leak rates?Typical LEP conversion is around $125 andwith gas at $6 MSCF, packing case leakageshould be identified and fixed.Monitoring emissions reduces greenhousegas release.


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Reduce Fugitive Emissions


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Summary

Packing is a dynamic seal designed torestrict leakage.Verify your current leakage rate.Low Emission Packing (LEP) is aninexpensive conversion to reduce fugitiveemissions.


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Questions?

Thank you!

Pressure Packing Presentation

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