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Mitchell Scientific, Inc.
Chapter 16: Methods for Estimating Air Emissions from Chemical
Manufacturing Facilities
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GUIDANCE DOCUMENT EVOLUTION
1978 CTG
1994 ACT
2007 CHAPTER 16
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CHAPTER 16 BASIC PRINCIPLES
APPLIES TO MOST CHEMICAL PROCESS OPERATIONS
PROVIDES STANDARDIZED CALCULATIONS
CONSERVATIVE ESTIMATES (WORST CASE)
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IDEAL GAS LAW
n PVRT=
nRT PV=
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DALTON’S LAW
n PVRTi
i=
P P P P PT n= + + + +• • •1 2 3
n n n n nT n= + + + +• • •1 2 3
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PURE COMPONENTVAPOR PRESSURE
0.00
500.00
1000.00
1500.00
2000.00
2500.00
3000.00
0 10 20 30 40 50 60 70 80 90 100
ACETONE
ETHYL ACETATE
WATER
TOLUENE
TEMPERATURE °C
PRESSURE(mm Hg)
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PURE COMPONENTVAPOR PRESSURE MODELS
( TYPICAL OF ALL VOLATILE ORGANIC COMPOUNDS )
T = T = °°K, K, °°C, C, °°F, F, °°R, ???R, ???
•Clapeyron Equation
•Antoine Equation
•Riedel Equation
•DIPPER Database Equation
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RAOULT’S LAW
p x Pi i i=
iiii Pxp γ=
IDEAL MIXTURE
NON IDEAL MIXTURE
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Mole Fraction of Component ‘i’ in Gas Space
T
ii P
py =
iiii Pxp γ=
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FILLING OPERATIONS
Equations
RTPVEn =
RTVpE i
i =
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PARTIAL PRESSURE RATIO MODELS
nc
inci p
pnn =
nc
i
nc
i
pp
nn
=
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PURGE / SWEEP OPERATIONS
satnc
sati
incRnc
incRiR p
pSE
pp
EE −−− ==
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PURGE / SWEEP OPERATIONS
KAFKA
Pp
S Sati
ii +
==
Vapor Pressure Saturation Level in Exit Purge Gasas a Function of F, K, A
00.10.20.30.40.50.60.70.80.9
1
0 20 40 60 80 100 120
Purge Rate (ft3/min)
Satu
ratio
n Le
vel
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VACUUM OPERATION
Equationnc
inci p
pEE =
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GAS EVOLUTION
Equation
rxn
irxni p
pEE =
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DYNAMIC CHANGING CONDITION MODELS
EMPTY VESSEL PURGE
DEPRESSURIZATION
HEATING
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EMPTY VESSEL PURGE
Equations
VFtii epp /1,2,−=
⎟⎠⎞⎜
⎝⎛ −=
−−
VFti
in eRT
VpE 11,
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DEPRESSURIZATION
⎟⎟⎠
⎞⎜⎜⎝
⎛=
2,
1,,, ln
nc
ncvslvocoutvoc P
Pnn
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HEATING
( )headspacevocvoc
nc
ncavgoutvoc nn
pp
Nn 1.2,2,
1,, ln −−⎟
⎟⎠
⎞⎜⎜⎝
⎛=
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PROCESS OPERATIONS
LIQUID TRANSFERS / FILLING OPERATIONSFILLED VESSEL PURGE OPERATIONSGAS SWEEP MODELSEMI-CONTINUOUS VACUUM OPERATIONSGAS EVOLUTIONEMPTY VESSEL PURGETEMPERATURE ELEVATIONSYSTEM DEPRESSURIZATIONOTHER ACTIVITIES . . .
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SINGLE STAGE VENT DEVICES
VENT CONDENSERSLIQUID RING VACUUM PUMPSVACUUM STEAM JETS
ACETONEACETONEMeOHMeOHTHFTHF
65%65%95%95%88%88%
35%35%5%5%12%12%
EFFICIENCYEFFICIENCY
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CONDENSERS
AcetoneAcetoneMethanolMethanol
THFTHF. . . . . .
NitrogenNitrogen
TT°°C ?C ?P ?P ?
AcetoneAcetoneMethanolMethanol
THFTHFNitrogen Nitrogen
AcetoneAcetoneMethanolMethanol
THFTHFCondensateCondensate
EmissionsEmissions
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VACUUM PUMP
AcetoneAcetoneMethanolMethanol
THFTHF. . . . . .
NitrogenNitrogen
TT°°C ?C ?P ?P ?
AcetoneAcetoneMethanolMethanol
THFTHFNitrogen Nitrogen
AcetoneAcetoneMethanolMethanol
THFTHF
EmissionsEmissions
LIQUID RING VACUUM PUMP
DISCHARGESUPPLY
Process VentProcess Vent
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VACUUM STEAM JET
AcetoneAcetoneMethanolMethanol
THFTHF. . . . . .
NitrogenNitrogen
TT°°C ?C ?P ?P ?
AcetoneAcetoneMethanolMethanol
THFTHF
EmissionsEmissionsProcess VentProcess Vent
condensate
steam
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SINGLE STAGE VENT DEVICESModified RachfordModified Rachford--Rice EquationRice Equation
( ) ( )( ) 0
111
11=+
−+−
= ∑∑==
nccond C
i
iC
i i
ii
FVz
FVKzK
FVf
i
ii x
yK =
ki
kLikLi
nn
,
,,1,, φ=+
Fi
ViLii n
nn
,
,, +=φ
( )( )ki
kikLikLi nf
nfnn
,
,,,1,, '−=+ ViLii ppnf ,,)( −=
Partial Pressure Correction MethodPartial Pressure Correction Method
Partial Pressure Correction MethodPartial Pressure Correction Method
