Colorado School of Mines
Pollution Prevention
Fugitive Emissions
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Fugitive Emissions

Unintentional releases, such as those due
to leaking equipment, are known as
fugitive emissions


Can originate at any place where
equipment leaks may occur
Can also arise from evaporation of
hazardous compounds from open topped
tanks
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Fugitive Emissions
Sources
Pumps and Valves
Tanks
Measurement
Calculation
Prevention
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Sources of Fugitive Emissions
Agitator seals
Loading arms
Compressor seals
Meters
Connectors
Open-ended lines
Diaphrams
Polished rods
Drains
Pressure relief devices
Dump lever arms
Pump seals
Flanges
Stuffing boxes Pumps
Hatches
Valves
Instruments
Vents
Drains
1%
27%
Valves
43%
Flanges
3%
Relief valves
18%
Compressors
8%
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Sources of Fugitive Emissions
Pumps and Valves
70% of process plant fugitive
emissions are from pumps and valves
 Measurement of fugitive emissions
will require some level of knowledge
of pumps and valves

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Sources of Fugitive Emissions
Pump Packing
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Sources of Fugitive Emissions
Centrifugal Pump
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Sources of Fugitive Emissions
Pump and Motor Assembly
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Sources of Fugitive Emissions
Pumps and Flanges
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Sources of Fugitive Emissions
Gate Valve
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Sources of Fugitive Emissions
Globe Valve
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Sources of Fugitive Emissions
Gate Valve
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Sources of Fugitive Emissions
Globe Valve
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Sources
Check Valve
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Sources: Butterfly Valves
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Sources of Fugitive Emissions
Flanges
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Sources of Fugitive Emissions
Flanges
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Piping Systems

One line diagrams



Valves
Pumps
Pipes
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Tanks
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Tanks
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Tanks
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Tanks
Fugitive Emissions


Tanks are designed to reduce fugitive
emissions
Floating roof tanks are typically used for
very large diameter tanks where a fixed
roof construction becomes expensive to
support and for products where vapor
emissions become an issue
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Fugitive Emissions from Storage
Tanks
There are six basic tank designs
 Fixed roof




vertical or horizontal
least expensive
least acceptable for storing liquids
emission are caused by changes in



temperature
pressure
liquid level
(a) Typical fixed-roof tank.
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Fugitive Emissions from Storage
Tanks

External floating roof




open-topped cylindrical steel shell
steel plate roof that floats on the surface of the liquid
emission limited to evaporation losses from
 an imperfect rim seal system
 fittings in the floating deck
 any exposed liquid on the tank wall when liquid is
withdrawn and the roof lowers
Domed external floating roof


similar to internal floating roof tank
existing floated roof tank retrofitted with a fixed roof to
block winds and minimize evaporative loses
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External Floating Roof Tanks
(b) External floating roof tank (pontoon
type).
(d) Domed external floating roof tank.
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Fugitive Emissions from Storage
Tanks

Internal floating roof


permanent fixed roof with
a floating roof inside
evaporative losses from
 deck fittings
 non-welded deck
seams
 annular space
between floating deck
and the wall
(c) Internal floating roof tank.
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Fugitive Emissions from Storage
Tanks

Variable vapor space
expandable vapor reservoirs to accommodate
volume fluctuations due to:
 temperature
 barometric pressure changes
 uses a flexible diaphragm membrane to provide
expandable volume
 losses are limited to:
 tank filling times when vapor displaced by
liquid exceeds tank’s storage capacity

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Measuring Fugitive Emissions
Instruments






Portable gas detector
Catalytic bead
Non-dispersive infrared
Photo-ionization detectors
Combustion analyzers
Standard GC with flame
ionization detector is
most commonly used
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Measuring Fugitive Emissions
Approach



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Average emission factor approach
Screening ranges approach
EPA correlation approach
Unit-specific correlation approach
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Measuring Fugitive Emissions

What factors can impact fugitive emission
measurement?
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Average Emission Factor Approach
ETOC  FA  WFTOC
ETOC = TOC emission rate from a component (kg/hr)
FA = applicable average emission factor for the component (kg/hr)
WFTOC = average mass fraction of TOC in the stream serviced by the component
Table 10.9
Average emission factors for estimating fugitive emissions
TOC emission factor
(kg/hr/source)
SOCMI
Refinery
Marketing
Terminal
Gas
Light liquid
Heavy liquid
0.00597
0.00403
0.00023
0.0268
0.0109
0.00023
1.3x10-5
4.3x10-5
-
Gas
Light liquid
Heavy liquid
0.0199
0.00862
0.144
0.021
6.5x10-5
5.4x10-4
Equipment type
Service
Valves
Pump seals
-
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Screening Ranges Approach


Leak/ No-leak approach
more exact than the average emissions
approach

relies on screening data from the facility,
rather than on industry wide averages
ETOC  ( FG  N G)  ( FL  N L )
TOC emission rate for an equipment type
FG
=
applicable emission factor for sources with screening values greater than
or equal to 10,000 ppmv (kg/hr/source)
NG
=
equipment count for sources with screening values greater than or equal to
10,000 ppmv
FL
=
applicable emission factor for sources with screening values less than
10,000 ppmv (kg/hr/source)
NL
= equipment count for sources with screening values less than 10,000 ppmv
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EPA Correlation Approach



Predicts mass emission rates as a function of
screening values for a particular equipment
type
Total fugitive emissions = sum of the
emissions associated with each of the
screening values
Default-zero leak rate is the mass emission
rate associated with a screening value of zero
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EPA Correlation Approach
Table 10.11
EPA correlations for estimating fugitive emissions
Equipment type
TOC leak rate from correlation*
(kg/hr/unit)
Default-zero
emission rate
(kg/hr/unit)
SOCMI
Refinery
Gas valves
1.8 x 10-6 SV0.873
-
6.6 x 10-7
Liquid liquid valves
6.41 x 10-6SV0.797
-
4.9 x 10-7
-
2.29 x 10-6 SV0.746
7.8 x 10-6
1.90 x 10-5 SV0.824
-
7.5 x 10-6
-
5.03 x 10-5SV0.610
2.4 x 10-5
Connectors
3.05 x 10-6SV0.885
-
6.1 x 10-7
Connectors
-
1.53 x 10-6SV0.735
7.5 x 10-6
Flanges
-
4.61 x 10-6SV0.703
3.1 x 10-7
Open-ended lines
-
2.20 x 10-6SV0.704
2.0 x 10-6
Valves (all)
Light liquid pumps
Pump seals (all)
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Unit-Specific Correlation
Approach



Most exact, but most expensive method
Screening values and corresponding mass
emissions data are collected for a
statistically significant number of units
A minimum number of leak rate
measurements and screening value pairs
must be obtained to develop the
correlations
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Controlling Fugitive Emissions


Modifying or replacing existing equipment
Implementing a leak detection and repair
(LDAR) program
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Equipment Modification
Equipment type
Modification
Approximate
control
efficiency
(%)
Pumps
Sealless design
100
Closed-vent system
90
Dual mechanical seal with barrier fluid maintained
at a higher pressure than the pumped fluid
100
Closed-vent system
90
Dual mechanical seal with barrier fluid maintained
at a higher pressure than the pumped fluid
100
Closed-vent system
varies
Rupture disk assembly
100
Valves
Sealless design
100
Connectors
Weld together
100
Open-ended lines
Blind, cap, plug or second valve
100
Sampling
connections
Closed-loop sampling
100
Compressors
Pressure-relief
devices
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Equipment Modification
Magnetic Drive Pump
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LDAR Programs


Designed to identify pieces of equipment
that are emitting sufficient amounts of
material to warrant reduction of emissions
through repair
Best applied to equipment types that can
be repaired on-line or to equipment for
which equipment modification is not
suitable
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Emissions Estimation from Storage Tanks
LT  LS  LW
LT = total losses, kg/yr
LS = standing storage losses, kg/yr
LW = working losses, kg/yr
MV PVA
WV 
RTLA
MV = vapor molecular weight
R = universal gas constant, mm Hg-L/EKThe standing storage losses are due to
mol
breathing of the vapors above the liquid in the P = vapor pressure at daily average liquid
VA
storage tank
surface temperature,
TLA = daily average liquid surface
LS  365VV WV KE KS
temperature, EK
m3
VV = vapor space volume,
WV = vapor density, kg/m3
KE = vapor space expansion factor,
dimensionless
KS = vented space saturation factor,
dimensionless
365 = days/year
 TV  PV   PB
KE 

TLA
PA  PVA
)TV = daily temperature range, EK
)PV = daily pressure range,
)PB = breather vent pressure setting range,
PA = atmospheric pressure,
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Emissions Estimation from Storage Tanks
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KS 
1  0.053PVA HVO
HVO =
vapor space outage, ft = height of a cylinder of tank diameter, D,
whose volume is equivalent to the vapor space volume of the tank
LW  0.0010 MV PVAQKN KP
Q = annual net throughput (tank capacity (bbl) times annual turnover rate), bbl/yr
KN = turnover factor, dimensionless
for turnovers > 36/year, KN = (180 + N)/6N
for turnovers # 36, KN = 1
where N = number of tank volume turnovers per year
KP = working loss product factor, dimensionless
for crude oils = 0.75
for all other liquids = 1.0
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Fugitive Emissions from Waste,
Treatment
and
Disposal
I = important
S = secondary
N = negligible or not applicable
Pathway
Surface
Wastewater treatment plants
impoundments Aerated
Non-aerated
Land
treatment
Landfill
Volatilization
I
I
I
I
I
Biodegradation
I
I
I
I
S
Photodecomp.
S
N
N
N
N
Hydrolysis
S
S
S
N
N
Oxidation/red’n
N
N
N
N
N
Adsorption
N
S
S
N
N
Hydroxyl radical
N
N
N
N
N
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