Page 272 - Biomass Gasification, Pyrolysis And Torrefaction Practical Design and Theory

248 Biomass Gasification, Pyrolysis and Torrefaction

t time (s)
u g superficial gas velocity in Eq. (7.79) (m/s)
U fluidization velocity (m/s)
U B bubble rise velocity (m/s)
U mf minimum fluidization velocity (m/s)
X fractional change in the carbon mass of the biomass ( )
y mole fraction of a species ( )
mole fraction of gas in the bulk ( )
y l
mole fraction of gas on the char surface ( )
y ls
z height above grid or distance along a reactor from fuel
entry (m)
stoichiometric coefficient for lth gas in kth reaction ( )
α l,k
β partition coefficient ( )
λ Lagrangian multiplier ( )
thermal conductivity of gas (kJ/m K)
λ g
4
2
σ Stefan Boltzmann constant (5.67 3 10 28 W/m /K )
ΔG,ΔG 0 change in Gibbs free energy (kJ)
ΔG 0 fi change in Gibbs free energy of formation of species i (kJ)
Δξ k extent of gas-phase kth reaction ( )
3
ρ j density of jth gas (kg/m )
Q mf voidage at minimum fluidization condition
ρ g density of the bulk gas
ΔS entropy change (kJ/K)