MODELING CHAR OXIDATION AS A FUNCTION OF PRESSURE ...
MODELING CHAR OXIDATION AS A FUNCTION OF PRESSURE ... MODELING CHAR OXIDATION AS A FUNCTION OF PRESSURE ...
vc the volume of combustible material in a char particle W neighbor in the negative x direction, i.e., on the west side x oxygen mole fraction xa fraction of ash Greek symbols power index of the normalized density-diameter relationship observed reaction rate over the maximum reaction rate allowed by boundary layer diffusion H1 heat of reaction for C + O2 → CO2 H2 heat of reaction for C + 0.5O2 → CO emissivity second effectiveness factor total porosity M macro porosity micro porosity ( - 1)/( + 1) effectiveness factor thermal conductivity o, O, O2 stoichiometric coefficient of oxygen for each mole of carbon consumed fraction of covered carbon sites normalized oxygen concentration, equal to C/Cs particle density, g/cm 3 , p app b a c apparent density, same as particle density, g/cm 3 bed density, defined as mass of particle/(volume of solid + intra-particle void volume + inter-particle void volume) density of ash, g/cm 3 density of combustible material, g/cm 3 tortuosity factor roughness factor normalized r, equal to r/rs fraction of carbon converted to CO2 for each mole of carbon consumed Subscript a ash c combustible material diff diffusion E neighbor in the positive x direction e effective f at film temperature, T f = 0.5(T p + T g) g bulk steam xviii
in intrinsic K Knudsen diffusion M macro o initial obs observed P central grid point under consideration rxn reaction W neighbor in the negative x direction s on external surface μ micro ∞ in the bulk stream xix
- Page 1 and 2: MODELING CHAR OXIDATION AS A FUNCTI
- Page 3 and 4: BRIGHAM YOUNG UNIVERSITY As chair o
- Page 5 and 6: CBK model uses: 1) an intrinsic Lan
- Page 7 and 8: Table of Contents List of Figures..
- Page 9: Appendices.........................
- Page 12 and 13: Figure A.2. Mass releases of the Ko
- Page 14 and 15: Table 7.6. Parameters Used in Model
- Page 16 and 17: Ed activation energy of desorption,
- Page 21 and 22: Background 1. Introduction The rate
- Page 23: the CBK model developed at Brown Un
- Page 26 and 27: Zone III rate ∝ C og E obs → 0
- Page 28 and 29: coal-general kinetic rate constants
- Page 30 and 31: Boundary Layer Diffusion The molar
- Page 32 and 33: = q obs q max The factor can be use
- Page 34 and 35: where k 1 and K are two kinetic par
- Page 36 and 37: particle can therefore be convenien
- Page 38 and 39: This is the first time that the gen
- Page 40 and 41: Data of Mathias Mathias (1996) perf
- Page 42 and 43: urn with shrinking diameters, and t
- Page 45 and 46: 3. Objectives and Approach The obje
- Page 47 and 48: Introduction 4. Analytical Solution
- Page 49 and 50: Task and Methodology Task One of th
- Page 51 and 52: 2 [ (i +1) − (i − 1)] i b = −
- Page 53 and 54: Table 4.1. The Relative Error * (%)
- Page 55 and 56: The resulting observations regardin
- Page 57 and 58: correction. The values of functions
- Page 59 and 60: Table 4.6. The Relative Error* (%)
- Page 61 and 62: Table 4.8. The Relative Error* (%)
- Page 63 and 64: general asymptotic solution. An arc
- Page 65 and 66: 5. Theoretical Developments The int
- Page 67 and 68: order of a reaction is usually dete
vc the volume of combustible material in a char particle<br />
W neighbor in the negative x direction, i.e., on the west side<br />
x oxygen mole fraction<br />
xa fraction of ash<br />
Greek symbols<br />
power index of the normalized density-diameter relationship<br />
observed reaction rate over the maximum reaction rate allowed by<br />
boundary layer diffusion<br />
H1 heat of reaction for C + O2 → CO2 H2 heat of reaction for C + 0.5O2 → CO<br />
emissivity<br />
second effectiveness factor<br />
total porosity<br />
M<br />
macro porosity<br />
micro porosity<br />
( - 1)/( + 1)<br />
effectiveness factor<br />
thermal conductivity<br />
o, O, O2 stoichiometric coefficient of oxygen for each mole of carbon consumed<br />
fraction of covered carbon sites<br />
normalized oxygen concentration, equal to C/Cs particle density, g/cm 3<br />
, p<br />
app<br />
b<br />
a<br />
c<br />
apparent density, same as particle density, g/cm 3<br />
bed density, defined as mass of particle/(volume of solid + intra-particle<br />
void volume + inter-particle void volume)<br />
density of ash, g/cm 3<br />
density of combustible material, g/cm 3<br />
tortuosity factor<br />
roughness factor<br />
normalized r, equal to r/rs fraction of carbon converted to CO2 for each mole of carbon consumed<br />
Subscript<br />
a ash<br />
c combustible material<br />
diff diffusion<br />
E neighbor in the positive x direction<br />
e effective<br />
f at film temperature, T f = 0.5(T p + T g)<br />
g bulk steam<br />
xviii
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