8/13/2019 Pressure Packing Presentation
1/20
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
8/13/2019 Pressure Packing Presentation
2/20
Engine and Compressor
8/13/2019 Pressure Packing Presentation
3/20
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
8/13/2019 Pressure Packing Presentation
4/20
Compressor Cylinder Cut Away
8/13/2019 Pressure Packing Presentation
5/20
Standard Packing Case
8/13/2019 Pressure Packing Presentation
6/20
Pressure Activates Packing
8/13/2019 Pressure Packing Presentation
7/20
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)
8/13/2019 Pressure Packing Presentation
8/20
Typical Packing Leak Paths
8/13/2019 Pressure Packing Presentation
9/20
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
8/13/2019 Pressure Packing Presentation
10/20
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
8/13/2019 Pressure Packing Presentation
11/20
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
8/13/2019 Pressure Packing Presentation
12/20
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
8/13/2019 Pressure Packing Presentation
13/20
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.
8/13/2019 Pressure Packing Presentation
14/20
LEP Packing Configuration
8/13/2019 Pressure Packing Presentation
15/20
Orientation in Cup
8/13/2019 Pressure Packing Presentation
16/20
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?
8/13/2019 Pressure Packing Presentation
17/20
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.
8/13/2019 Pressure Packing Presentation
18/20
Reduce Fugitive Emissions
8/13/2019 Pressure Packing Presentation
19/20
Summary
Packing is a dynamic seal designed torestrict leakage.Verify your current leakage rate.Low Emission Packing (LEP) is aninexpensive conversion to reduce fugitiveemissions.
8/13/2019 Pressure Packing Presentation
20/20
Questions?
Thank you!