Page 13 - Pressure Swing Adsorption

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LIST OF SYMBOLS CONTENTS xm
c, volumetnc heat capacity of soi id (pC ,..)
p" high pressure (at end of pressunzat10n)
CJISlcd heat caoaclty of steel wall (mass basts) (Table 5. IO)
a mternal diameter of adsorbent coiurnn J\ feed pressure
D diffus1v1ty PL low pressure (during purge step}
D, microoore or mtracrystalline diffusivity pelf high pressure for compressor
D. effective diffusivity P,L low pressure for comoressor
DK Knudsen diffusivity Pe Peclet number (u HL/DL)
0
DL axial dispersion coefticient IP ahsolutc pressure ratio P 11 / Pi,
Dm molecular diffus1v1ty IP' pressure ratio PH/PF
D, oore ditfus1v1ty IP F pressure ratio PF/ P1.
E diffusmnaJ activation energy IP H pressure ratm PH/PL (end of oressunzation versus end of
EA ennchment of heavy component (y /y AF) blowdown)
' absolute compress1on ratio PcHI PcL
Ji, J isotherm function for component i at composition
!/ isotherm slope (da* /de) at composition 1 adsorbed phase concentratmn
F total feed volume 1 eauilibrium vaiue of a
F.~ free energy of adsorbed phase (Eo. 2.11) vaiue of a at equilibnum with feed (concentration c)
FA, FB value of a averageG over an adsorbent oart1cle
fractions of comoonents A, B desorbed from column during saturation limtt
depressunzat10n
molar gas flow rate
purge.to-feed velocity ratio
radial coordinate m rn1crooart1cle
Gibbs free energy of adsorbed Phase (Eq, 2.8) m1croparticle radius
overall heat transfer coefficient inner and outer radii of column
enthalpy change on adsorption
flux of sorbate radial coordinaie m a m1crooart1cle; gas constant (RR); product
recovery
overall mass transfer (LDF) rate coefficient based on macrooarticie radius
adsorbed Phase concentrat10n
K equilibnum seiect1v1ty KA/K 8
actsorotion equilibrium constant or isotherm slooe; constant in kinetic selectivity DA/D
Ea. 7.5 8
Kc adsorption equilibrium constant on crystal (micropartJCie) volume Sherwood number 2Rpkr/Dm
K' ,. time
adsorvt10n eauilibnum constant or isotherm slope based on adsorption or desorot1on time
sorbate pressure
temperature
pre-exponent1al factors (Eq. 2.2)
feed temoerature
effective thermat conduct1v1ty of steel wall (Table 5.10) internal energy change or adsorption
adsorbent bed length
tnterstitial gas velocity
_Phenomenological coefficients
Interstitial gas velocity at mlet
moJecuiar weight; constant in auadratic isostherm expression
fl dimens1onless mterstttal gas velocity u/v H
exponent 111 Freundlich 1sothenn exoress10n 0
n., motes of actsorbable component (Eq, 2.8) volume
n,. moJes of solid adsorbent (Eo. 2.8) velocity of concentration front
N velocity of temperature front
flux relative to fixed frame of reference (Eo. 2.26); total moles velocity of shock front
(gaseous anct adsorbed) in bed at time t
p partial pressure of sorbate mole fraction (of component A) m adsorbed ohase; dimensionless
P, saturation vapor pressure adsorbed phase concentration averaged over a
p macropart1cle citliiis
absolute pressure On column)
P' dimensionless adsorbed phase concentration averaged over a
rate of change of pressure durmg feed step (Eq. 4.35)
m1crooart1cle (q/q)