EPA’s Natural Gas STAR Program, El Paso Corporation, and Southern Gas Association

Gas STAR Technologies and PracticesGas STAR Technologies and Practicesfor DI&M and Compressor Sealsfor DI&M and Compressor Seals

((Opportunities for Cost Effective Methane Sensors)Opportunities for Cost Effective Methane Sensors)

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

El Paso Corporation, andEl Paso Corporation, and

Southern Gas AssociationSouthern Gas AssociationOctober 27, 2003October 27, 2003

Page 2Reducing Emissions, Increasing Efficiency, Maximizing Profits

AgendaAgenda Equipment leaksEquipment leaks

What is the problem?What is the problem? Where are the leaks?Where are the leaks? What Gas STAR Partners are doing.What Gas STAR Partners are doing. A low-cost sensor option.A low-cost sensor option.

Compressor sealsCompressor seals What is the problem?What is the problem? Where are the leaks?Where are the leaks? What Gas STAR Partners are doing.What Gas STAR Partners are doing. A low-cost sensor option.A low-cost sensor option.


STAR partners find that valves, STAR partners find that valves, connectors, compressors and open-connectors, compressors and open-ended lines (OEL) are major leak sourcesended lines (OEL) are major leak sources 50.7 Bcf/yr of methane are emitted by 50.7 Bcf/yr of methane are emitted by

compressors and facility componentscompressors and facility components 1% of the leakers contribute 90% of the 1% of the leakers contribute 90% of the

emissionsemissions Fugitive emissions depend on operating Fugitive emissions depend on operating

practices, equipment age and practices, equipment age and maintenancemaintenance

Equipment leaksEquipment leaksWhat is the Problem?What is the Problem?


Distribution of Natural Gas Losses Distribution of Natural Gas Losses by Source Categoryby Source Category

Combustion EquipmentCombustion Equipment9.9%9.9%

Amine VentsAmine Vents0.5%0.5%

Flare SystemsFlare Systems24.4%24.4%

Non-leaking ComponentsNon-leaking Components0.1%0.1%

NRU VentsNRU Vents0.3%0.3%

Storage TanksStorage Tanks11.8%11.8%

Leaking ComponentsLeaking Components

53.1%53.1%

Source: Clearstone Engineering, 2002Source: Clearstone Engineering, 2002


Natural Gas Losses from Natural Gas Losses from Equipment Leaks by Type of ComponentEquipment Leaks by Type of Component

Control ValvesControl Valves4.0%4.0%

Open-Ended LinesOpen-Ended Lines11.1%11.1%

Other Flow MetersOther Flow Meters0.2%0.2%

Orifice MetersOrifice Meters0.1%0.1%

Pressure Relief ValvesPressure Relief Valves3.5%3.5%

ValvesValves26.0%26.0%

BlowdownsBlowdowns0.8%0.8%

ConnectorsConnectors24.4%24.4%

Compressor SealsCompressor Seals23.4%23.4%

Crankcase VentsCrankcase Vents4.2%4.2%

Pump SealsPump Seals1.9%1.9%

Pressure RegulatorsPressure Regulators0.4%0.4%

Source: Clearstone Engineering, 2002Source: Clearstone Engineering, 2002


Where are the leaks?Where are the leaks?

Valves account for 30%Valves account for 30% Block valves = 26%Block valves = 26% Control valves = 4%Control valves = 4%

Stem seal leaks are the Stem seal leaks are the primary sourceprimary source Balance between packing Balance between packing

pressure and valve pressure and valve movement forcemovement force

Packing wears, requiring Packing wears, requiring either more pressure or either more pressure or replacementreplacement



Open ended lines (OEL) Open ended lines (OEL) account for 11%account for 11% Block valvesBlock valves Blowdown vents, motor Blowdown vents, motor

starters, vent and drain starters, vent and drain connectionsconnections

Through-valve leakage is Through-valve leakage is the primary sourcethe primary source Often from vent stacksOften from vent stacks Valve seat wears or fouls, Valve seat wears or fouls,

requiring either more requiring either more pressure, cleaning or pressure, cleaning or replacementreplacement



Pressure Relief Valves Pressure Relief Valves (PRV) account for 3.5%(PRV) account for 3.5% Fewer of them, so higher Fewer of them, so higher

individual leakageindividual leakage Protect equipment from Protect equipment from

over-pressureover-pressure Through-valve leakage is Through-valve leakage is

the primary sourcethe primary source Often from vent stacksOften from vent stacks Valve seat wears or Valve seat wears or

fouls, requiring either fouls, requiring either cleaning or replacementcleaning or replacement


What Gas STAR Partners are doing?What Gas STAR Partners are doing? Implementing a Directed Implementing a Directed

Inspection and Inspection and Maintenance Program Maintenance Program (DI&M)(DI&M) Voluntary program to identify Voluntary program to identify

and fix leaks that are cost and fix leaks that are cost effective to repaireffective to repair

Survey cost will pay out Survey cost will pay out in the first yearin the first year

Provides valuable data Provides valuable data on leakerson leakers

Acoustic Leak Detection

Leak Measurement Using a High Volume Sampler


Current DI&M TechniquesCurrent DI&M Techniques

Summary of Screening and Measurement Techniques

Instrument/

Technique Effectiveness

Approximate

Capital Cost

Soap Solution

$

Electronic Gas Detectors

$$

Acoustic Detection/ Ultrasound Detection

$$$

TVA (FID)

$$$

Bagging

$$$

High Volume Sampler

$$$

Rotameter

$$

Source: EPA’s Lessons Learned Study


Cost-Effective Repair ExamplesCost-Effective Repair Examples

Repair the Cost Effective Components

Component Value of

Lost gas1 ($)

Estimated Repair cost

($)

Payback (Months)

Plug Valve: Valve Body 12,641 200 0.2

Open-Ended Line 6,959 60 0.1

Pressure Relief Valve 982

293 3.5

Gate Valve 4,729 60 0.2

Source: Hydrocarbon Processing, May 2002 1Based on $3/Mcf gas price


Opportunities for Inexpensive Leak SensorsOpportunities for Inexpensive Leak Sensors

Application: Valves, Open-Ended Lines (OELs), Application: Valves, Open-Ended Lines (OELs), Pressure Relief Valves (PRVs)Pressure Relief Valves (PRVs)

Objective: Automated detection of LARGE leaks Objective: Automated detection of LARGE leaks that are cost-effective to repairthat are cost-effective to repair

Potential application:Potential application:

Equipment alerts operator to cost-effective leakEquipment alerts operator to cost-effective leak

Business as usual site visitBusiness as usual site visit

Operator directs repairs on the spotOperator directs repairs on the spot


DI&M – Transmission Partner ExperienceDI&M – Transmission Partner Experience Partner A: 15 Stations surveyed annually Partner A: 15 Stations surveyed annually

Survey and repairs averaged $350/station Survey and repairs averaged $350/station Methane savings averaged 11,067Mcf/stationMethane savings averaged 11,067Mcf/station

Partner B: 2 Stations surveyed quarterly Partner B: 2 Stations surveyed quarterly Survey costs $200/station Survey costs $200/station 24 leaks detected & repaired; 23 repaired at 24 leaks detected & repaired; 23 repaired at

average $50 eachaverage $50 each

Total Gas Savings $ 498,030Total Gas Savings $ 498,030

Total DI&M Cost Total DI&M Cost $ (5,250)$ (5,250)

SAVINGS $ 492,780SAVINGS $ 492,780

Total Gas Savings $ 51,240Total Gas Savings $ 51,240

Total DI&M Cost Total DI&M Cost $ (2,750)$ (2,750)

SAVINGS $ 48,490SAVINGS $ 48,490


Compressor sealsCompressor sealsWhat is the problem?What is the problem?

Compressor seals account for 23.4% of emissionsCompressor seals account for 23.4% of emissions 11.9 Bcf/yr of methane are emitted by compressors11.9 Bcf/yr of methane are emitted by compressors Over 8,500 compressors in gas transmission sectorOver 8,500 compressors in gas transmission sector

CompressorStation

CompressorStation

Production

32,000 Compressors

Processing

5,000 Compressors

Transmission & Storage

8,500 Compressors

Distribution

0 Compressors

CompressorStation


Where are the leaks?Where are the leaks? Reciprocating compressor rod packingReciprocating compressor rod packing

Fourth largest gas industry emissions at 16 Bcf/yrFourth largest gas industry emissions at 16 Bcf/yr Leakage typically occurs from:Leakage typically occurs from:

Nose gasketNose gasket Between cupsBetween cups Ring movementRing movement Down shaftDown shaft

All packings leakAll packings leak ~60 scfh new~60 scfh new >900 scfh worn>900 scfh worn

Distance Piece

Piston Rod

Lubrication

Flange

GasLeakage Piston Rod

(Side View, Cut in Half)

(Side View, Cut in Half)

OIL

Cylinder

Suction

Discharge

Cylinder Wall

High Pressure Gas Inside

Cylinder

Piston

Rod Packing Case

Two Rings(In Three Segments )

Springs

Packing Cup


Where are the leaks?Where are the leaks? Centrifugal compressor wet sealsCentrifugal compressor wet seals

90% of new compressors for transmission are 90% of new compressors for transmission are centrifugalcentrifugal

Leakage typically occurs from:Leakage typically occurs from: Labyrinth seal Labyrinth seal

into seal oil into seal oil Seal oil Seal oil degassing degassing

ventvent Very little leakage from Very little leakage from

seal faceseal face Seal oil vents emitSeal oil vents emit

40-200 scfm40-200 scfm

Spinning Shaft

Motor and

Shaft Bearing Side

“Outboard”

Compressor Side “Inboard”

Seal Oil Inlet

Seal Oil Outlet (Uncontaminated)

Seal Oil Outlet

(Contaminated with Gas)

“Outboard” Labyrinth

Seal

Seal Housing

Process Gas Leaks Through “Inboard”

Labyrinth Seal


Where are the leaks?Where are the leaks? Centrifugal compressor dry sealsCentrifugal compressor dry seals

Most new compressors are supplied with dry sealsMost new compressors are supplied with dry seals Leakage typically occurs from:Leakage typically occurs from:

Labyrinth seal into static barrierLabyrinth seal into static barrier Seal vent Seal vent

after tandem after tandem sealseal

Little leakage Little leakage from seal facefrom seal face

Seal vents emitSeal vents emit 0.5-3 scfm0.5-3 scfm Spinning

ShaftSprings Push Stationary

Ring Against Rotating Ring

Motor End

Tandem RotatingRings with Grooves

Gas Pressurebetween Rings

Prevents Process Gas From Leaking

Very Little ProcessGas Leakage

(Fugitive)

Process Gas Leaks Through

Labyrinth


What Gas STAR Partners are doing.What Gas STAR Partners are doing.

Leakage is reduced through routine Leakage is reduced through routine monitoring and seal maintenancemonitoring and seal maintenance Conventional rod packing rings require Conventional rod packing rings require

replacement every 3 to 5 yearsreplacement every 3 to 5 years An economic leak rate is determined An economic leak rate is determined

based on costs and gas savingsbased on costs and gas savings Replace rings when it is economicalReplace rings when it is economical

Saves gas and moneySaves gas and money Extends the life of the piston rodExtends the life of the piston rod Reduces methane emissionsReduces methane emissions


Best Practice Compressor Emissions ControlBest Practice Compressor Emissions ControlCompressor Rod Packing SystemsCompressor Rod Packing Systems

Partners develop an “economic Partners develop an “economic replacement threshold” that defines replacement threshold” that defines

the point when it is cost-effective to the point when it is cost-effective to replace rings and rodsreplace rings and rods

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 = company discount factor (%)DF = company discount factor (%)

H = hours of compressor operationH = hours of compressor operation

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


Economic AnalysisEconomic AnalysisCompressor Rod Packing SystemCompressor Rod Packing System

LRE(scfh)

PaybackPeriod1

(yrs)

83 1

43 2

30 3

24 4

20 5

1 Assumes packing ringreplacement 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)

PaybackPeriod1

(yrs)

564 1

295 2

206 3

162 4

135 51 Assumes packing ringreplacement costs of $1,200,rod replacement cost of $7,000,$3.00/Mcf gas and 8,000 hr/yr


Opportunities for Inexpensive Leak SensorsOpportunities for Inexpensive Leak Sensors

Application: Compressor seal and seal oil ventsApplication: Compressor seal and seal oil vents

Objective: Automated detection of LARGE leaks Objective: Automated detection of LARGE leaks that are cost-effective to repairthat are cost-effective to repair

Potential application:Potential application:

Equipment alerts operator to cost-effective leakEquipment alerts operator to cost-effective leak

Business as usual site visitBusiness as usual site visit

Operator schedules cost-effective repairsOperator schedules cost-effective repairs


Company ExperienceCompany 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 Replaced packing cases at eight stations costing $1,050 per case, installedcosting $1,050 per case, installed

• Saved 55 MMcf/yr valued at $165,000Saved 55 MMcf/yr valued at $165,000


DiscussionDiscussion Questions Questions

How accurate would sensors need to be How accurate would sensors need to be in quantifying methane emissions?in quantifying methane emissions?

Would methane emissions sensor Would methane emissions sensor outputs need to be transmitted to a outputs need to be transmitted to a SCADA center?SCADA center?

To what degree are candidate sites for To what degree are candidate sites for low cost fugitive sensors non-electrified?low cost fugitive sensors non-electrified?

What are other applications for What are other applications for inexpensive methane emissions inexpensive methane emissions sensors?sensors?

Documents

EPA’s Natural Gas STAR Program, El Paso Corporation, and Southern Gas Association