Embed Size (px)
DESCRIPTION
Separations Lab Presentation
Citation preview
Gas Membrane Separation Gas Membrane Separation
Separations & Reaction Engineering LabSeparations & Reaction Engineering LabMarch 21, 2006March 21, 2006
Kate CannadyKate Cannady
Christopher MillerChristopher Miller
Matt MobilyMatt Mobily
Jennifer PrattJennifer Pratt
Today’s ScheduleToday’s Schedule
• Introduction & ApplicationsIntroduction & Applications• Design ChallengeDesign Challenge• Apparatus & MethodsApparatus & Methods• TheoryTheory• Preliminary Data, Results & Thoughts Preliminary Data, Results & Thoughts
on Scale Upon Scale Up• Conclusions & Future PlansConclusions & Future Plans• ReferencesReferences
What is Gas Membrane Separation?What is Gas Membrane Separation?
• Separation of a known component into Separation of a known component into two product streams (known as the two product streams (known as the permeate and reject, or retentate) permeate and reject, or retentate) through a semi-permeable polymeric through a semi-permeable polymeric membranemembrane – Permeate is oxygen rich (smaller)Permeate is oxygen rich (smaller)– Reject is nitrogen rich (larger)Reject is nitrogen rich (larger)
Industrial Uses?Industrial Uses?
• HH22 Separation Separation– HH22/N/N22 separation in ammonia plants & H separation in ammonia plants & H22/hydrocarbon /hydrocarbon
separation in petrochemical applicationsseparation in petrochemical applications
• NN22/Air Separation/Air Separation• COCO22 & H & H22O removal from natural gasO removal from natural gas• Organic vapor removal from air or NOrganic vapor removal from air or N22 streams streams• InertingInerting
– Chemical industry products stored in inert atmosphereChemical industry products stored in inert atmosphere– Reduces risk by removing OReduces risk by removing O22
• BlanketingBlanketing– Uses NUses N22 to ‘cover’ liquid to ‘cover’ liquid
• Prevents vaporizationPrevents vaporization• Maintains atmosphere to reduce ignition potentialMaintains atmosphere to reduce ignition potential• Prevents oxidation or contamination by reducing Prevents oxidation or contamination by reducing
exposure to atmospheric airexposure to atmospheric air
AdvantagesAdvantages• Separation units smaller than other types
– Small footprint = good for operations such as offshore gas-processing platforms
• Environmentally friendly (no waste product)• Wide operating parameters (flexible)• Requires less energy than other separation processes (no
phase change)• Very reliable • Lacks mechanical complexity – no supervision required
(low operating cost)
DisadvantagesDisadvantages
• Membrane fouling - more frequent than other membranes due to is configuration (contaminated feed) • Expensive - more so than other types available (fabrication method)• Lack of research - less research done compared to other types of membrane
Hollow FiberHollow Fiber
Factors to ConsiderFactors to Consider
• Properties of componentProperties of component– PermeabilityPermeability
• Relative permeation ratesRelative permeation rates
Slow: NSlow: N22, Ar, CO, Ar, CO
Medium: COMedium: CO22, O, O22
Fast: HFast: H22O, HO, H22, He, He
– DiffusivityDiffusivity– SelectivitySelectivity
• Properties of membraneProperties of membrane– MaterialMaterial– Estimated lifetimeEstimated lifetime– Size, shape & thicknessSize, shape & thickness
• Operating parametersOperating parameters– Feed flow rateFeed flow rate– Pressure settingsPressure settings
Industrial Hollow Fiber MembraneIndustrial Hollow Fiber Membrane
• Typically 300,000 – 500,000 individual fibersTypically 300,000 – 500,000 individual fibers– OD ~ 300OD ~ 300μμmm– ID ~ 150ID ~ 150μμmm– FYI – diameter of a human hair is ~ 100FYI – diameter of a human hair is ~ 100μμmm
• Housing usually 6-12” diameter and about 40” longHousing usually 6-12” diameter and about 40” long
Design ChallengeDesign Challenge
• Determine optimal conditions for Determine optimal conditions for separation of an air stream into enriched separation of an air stream into enriched O2 & N2 streams using hollow-fiber O2 & N2 streams using hollow-fiber membrane technologymembrane technology
• Size a membrane gas separator for a Size a membrane gas separator for a selected applicationselected application
Apparatus & MethodsApparatus & Methods• Initial calibration of flow Initial calibration of flow
controlled and flow metercontrolled and flow meter
• Oxygen analyzer Oxygen analyzer calibrated to 21% in calibrated to 21% in ambient conditions & ambient conditions & probe placed in collection probe placed in collection traptrap
• Inlet flow set to desired Inlet flow set to desired flow rate flow rate
• Pressure valves set to Pressure valves set to desired levelsdesired levels
• Once steady state Once steady state achieved, oxygen achieved, oxygen concentration recorded concentration recorded for both permeate and for both permeate and reject streamsreject streams
gas separation unit
collection trap
oxygen analyzer and probe
flow controller
permeate and reject pressure
controls
flow meters
flow inlet
• Procedure repeated varying flow rate and pressure settings Procedure repeated varying flow rate and pressure settings until desired data collecteduntil desired data collected
Polysulfone - CPolysulfone - C2727HH2222OO44SS
• Oxygen PermeabilityOxygen Permeability– PPAA = 1.38 = 1.38
• Nitrogen PermeabilityNitrogen Permeability– PPBB = 0.239 = 0.239
• SelectivitySelectivity– αα = P = PAA/P/PBB
– αα = 1.38/0.238 = 5.8 = 1.38/0.238 = 5.8
TheoryTheory
)( VA
LA
AA PyPx
t
PN
])1()1[( VA
LA
BB PyPx
t
PN
BA
BB NN
Ny
BA
AA NN
Ny
B
A
B
A
N
N
y
y
Flux of A across film:Flux of A across film:
Flux of B across film:Flux of B across film:
xxAA = mole fraction of A on high pressure = mole fraction of A on high pressure
side (reject)side (reject)
yyAA = mole fraction of A on low pressure = mole fraction of A on low pressure
side (permeate)side (permeate)
PPLL = reject pressure = reject pressure
PPVV = permeate pressure = permeate pressure
PPAA = permeability of A = permeability of A
PPBB = permeability of B = permeability of B
t = membrane thickness t = membrane thickness
A variation of Fick’s…A variation of Fick’s…
More Theory…More Theory…
B
A
P
P
)( VA
LA
AA PyPx
t
PN
])1()1[( VA
LA
BB PyPx
t
PN
In terms of selectivity: In terms of selectivity:
From before:From before:
andand
becomebecome)( V
AL
A
AA PyPx
tNP
])1()1[( VA
LA
BB PyPx
tNP
andand
And More Theory…And More Theory…
])1()1[(
)(
VA
LA
B
VA
LA
A
PyPxtNPyPx
tN
tN
PyPx
PyPx
tN
B
VA
LA
VA
LA
A )1()1(*)(
)(
)1()1(V
AL
A
VA
LA
B
A
PyPx
PyPx
N
N
So…So…
Recall thatRecall thatB
A
B
A
N
N
y
y
)(
)1()1(V
AL
A
VA
LA
B
A
PyPx
PyPx
y
y
Data & ResultsData & Results
• Highest OHighest O22 concentration at concentration at ΔΔPPmaxmax
• ConditionsConditions– Reject Pressure = 80psiReject Pressure = 80psi– Permeate Pressure = 10psiPermeate Pressure = 10psi
Flow Rate (mL/s)Flow Rate (mL/s)** OO2 2 Concentration (%)Concentration (%)
108108 27.4 27.4216216 33.4 33.4324324 36.5 36.5
** Flow rates adjusted based on calibration (originally 100, 200 and 300 mL/s) Flow rates adjusted based on calibration (originally 100, 200 and 300 mL/s)
Data & ResultsData & Results
For calculating selectivity…For calculating selectivity…
PPLL yyAA xxAAPPVV
yyB B = (1-y= (1-yAA))
)(
)1()1(V
AL
A
VA
LA
B
A
PyPx
PyPx
y
y
Data & ResultsData & Results
Selectivity Results for Collected Data:Selectivity Results for Collected Data:
Recall Recall ααidealideal = 5.80 = 5.80
Conclusions & To Do ListConclusions & To Do List
• ConclusionsConclusions– Highest O2 concentration at largest Highest O2 concentration at largest ΔΔP and at P and at
higher flow rateshigher flow rates– Overall experimental selectivity is a bit lower Overall experimental selectivity is a bit lower
than ideal than ideal • Increases with Increases with ΔΔP, but a change in flow rate does P, but a change in flow rate does
not appear to affect selectivitynot appear to affect selectivity
• To DoTo Do– Determine conditions for highest separation Determine conditions for highest separation
factorfactor– More data analysisMore data analysis– Scale-Up calculationsScale-Up calculations
ReferencesReferences
• Coker, D.T., Prabhakar, R. and Freeman, B. Gas Separation Coker, D.T., Prabhakar, R. and Freeman, B. Gas Separation Using Polymers. Chemical Engineering Education. Winter 2003. Using Polymers. Chemical Engineering Education. Winter 2003. 60-67.60-67.
• Membranes For Gas Separation. Chemical & Engineering News.Membranes For Gas Separation. Chemical & Engineering News.October 03, 2005. Volume 83: Number 40. 49-57.October 03, 2005. Volume 83: Number 40. 49-57.
• http://www.cheresources.com/blanketzz.shtmlhttp://www.cheresources.com/blanketzz.shtml
• http://www.polymerlabs.com/elsd/images/membrane.gifhttp://www.polymerlabs.com/elsd/images/membrane.gif
?
Brilliant!
??
? ?
? ?
? ???
?
?
Brilliant!
