methane emission reductions from reciprocating compressors

Methane Emission Reductions from Methane Emission Reductions from Reciprocating CompressorsReciprocating Compressors

Lessons Learned Lessons Learned

from Natural Gas STARfrom Natural Gas STAR

EPA’s Natural Gas STAR Program,EPA’s Natural Gas STAR Program,

Pioneer Natural Resources USA, Inc., andPioneer Natural Resources USA, Inc., and

The Gas Processors AssociationThe Gas Processors Association

June 17, 2003June 17, 2003

Reducing Emissions, Increasing Efficiency, Maximizing Profits

Methane Emission Reductions from Methane Emission Reductions from Reciprocating CompressorsReciprocating Compressors

Introduction to CompressorsIntroduction to Compressors Methane LossesMethane Losses Steps to Reduce Methane LossesSteps to Reduce Methane Losses Cost EffectivenessCost Effectiveness Future TrendsFuture Trends


Location and Types of CompressorsLocation and Types of Compressors

CompressorStation

CompressorStation

Production

32,000 Compressors

Processing

5,000 Compressors

Transmission & Storage

8,500 Compressors

Distribution

0 Compressors

CompressorStation


Reciprocating Compressor Rod Packing Reciprocating Compressor Rod Packing SystemsSystems


Methane LossesMethane Losses

Compressor seals are fourth largest Compressor seals are fourth largest emission source at 16 Bcf/yremission source at 16 Bcf/yr

Leakage typically occursLeakage typically occurs Around the packing case nose gasketAround the packing case nose gasket Between the packing cupsBetween the packing cups Around rings from slight movement in the cup Around rings from slight movement in the cup Between the rings and shaftBetween the rings and shaft

All packing systems normally leakAll packing systems normally leak New systems lose ~ 60 scfh New systems lose ~ 60 scfh Badly worn systems lose ~ 900 scfhBadly worn systems lose ~ 900 scfh


Steps to Reduce Methane LossesSteps to Reduce Methane Losses

Leakage can be reduced though monitoring Leakage can be reduced though monitoring and economic replacementand economic replacement Conventional packing rings need to be replaced Conventional packing rings need to be replaced

every 3 to 5 yearsevery 3 to 5 years An economic leak rate can be determined An economic leak rate can be determined

based on costs and gas savingsbased on costs and gas savings Replacing rings when it is economicalReplacing rings when it is economical

Saves gas and moneySaves gas and money Extends the life of the compressor rodExtends the life of the compressor rod


Economic AnalysisEconomic Analysis

Partners should develop an “economic Partners should develop an “economic replacement threshold” that defines the point replacement threshold” that defines the point when it is cost-effective to replace rings and when it is cost-effective to replace rings and rodsrods

Economic Replacement Threshold (scfh) =Economic Replacement Threshold (scfh) =

(CR * DF) / [(H * GP) /1,000](CR * DF) / [(H * GP) /1,000]where:where:

CR = cost of replacement ($)CR = cost of replacement ($)

DF = capital recoveryDF = capital recovery

H = hours of compressor operationH = hours of compressor operation

GP = gas price ($/Mcf)GP = gas price ($/Mcf)

DF = DF = i i ((1+ 1+ ii))nn /[(/[(1+ 1+ ii))nn –1]–1]


Economic AnalysisEconomic AnalysisCompressor Rod Packing SystemCompressor Rod Packing System

LRE (scfh)

Payback Period1

(yrs)

55 1

29 2

20 3

16 4

13 5

1 Assumes packing ring replacement costs of $1,200, $3.00/Mcf gas and 8,000 hr/yr

Economic Replacement Threshold

for Packing Rings

Economic Replacement Threshold

for Rod and Rings

LRE (scfh)

Payback Period1

(yrs)

376 1

197 2

137 3

108 4

90 5 1 Assumes packing ring replacement costs of $1,200, rod replacement cost of $7,000, $3.00/Mcf gas and 8,000 hr/yr


Partner ExperiencePartner Experience

One partner conducted semi-annual One partner conducted semi-annual inspections of compressor rod packinginspections of compressor rod packing Replaced packing cases at eight stations costing Replaced packing cases at eight stations costing

$1,050 per case, installed$1,050 per case, installed Saved 55 MMcf/yr valued at $165,000Saved 55 MMcf/yr valued at $165,000


Future TrendsFuture Trends

Install axially loaded rings in reciprocating Install axially loaded rings in reciprocating compressorscompressors

Install combination rings that serve as a Install combination rings that serve as a static seal when compressors are shut down static seal when compressors are shut down and kept pressurizedand kept pressurized

Vented and purged sealsVented and purged seals


Axially Loaded RingsAxially Loaded Rings

Source: Compressor Engineering Corporation


Three Ring Rod PackingThree Ring Rod Packing

Three ring rod packing is becoming more Three ring rod packing is becoming more wide spreadwide spread

The rings are typically installed in one of the The rings are typically installed in one of the last two cupslast two cups

This design could be installed without any This design could be installed without any replacement or modification on the packing replacement or modification on the packing case cupcase cup


Discussion QuestionsDiscussion Questions

To what extent are you implementing this To what extent are you implementing this Lesson Learned?Lesson Learned?

How can this Lesson Learned be improved How can this Lesson Learned be improved upon or altered for use in your operation(s)?upon or altered for use in your operation(s)?

What are the barriers (technological, What are the barriers (technological, economic, lack of information, regulatory, economic, lack of information, regulatory, etc.) that are preventing you frometc.) that are preventing you from implementing this technology?implementing this technology?

methane emission reductions from reciprocating compressors

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