THERMOCHEMICAL CONVERSION: AN INTRODUCTION TO FAST PYROLYSIS - Biomass as a Sustainable Energy Source for the Future - page 382

V s , 0 = ρ b +

V s ð ρ c + ρ ab Þ

: :

ð Eq 11 13 Þ

ρ b , 0

i=1

E a , i
R u T

k i =k 0 , i exp

− : :

… 3 ð Eq 11 14 Þ

r 1 =k 1 ρ b ð Eq : 11 : 15 Þ

r i =k i ρ ab i = 2, 3 ð Eq : 11 : 16 Þ

ρ b = m b
V

ð Eq : 11 : 17a Þ

ρ c = m c ð Eq : 11 : 17b Þ

V

ρ g = m g

V g = m g

ð Eq : 11 : 17c Þ

ε V

= V g
V

ε ð Eq : 11 : 17d Þ

V g =V − V s ð Eq : 11 : 17e Þ

Q r =k 1 ρ b Δ h 1 +T ð − T 0 Þ c p , b − c p , ab

+k 2 ρ ab Δ h 2 +T ð − T 0 Þ c p , ab − ν c c p , c − ν g c p , g

+k 3 ρ ab Δ h 3 +T ð − T 0 Þ c p , ab − c p , v ð Eq : 11 : 18 Þ

T 3 d x
ω

λ x = χλ b , x +1 ð − χ Þ λ c : x + ε λ g + σ ð Eq : 11 : 19 Þ

T 3 d y
ω

λ y = χλ b , y +1 ð − χ Þ λ c : y + ελ g + σ ð Eq : 11 : 20 Þ

B x = χ B b , x +1 ð − χ Þ B c : x ð Eq : 11 : 21 Þ

B y = χ B b , y +1 ð − χ Þ B c : y ð Eq : 11 : 22 Þ

= ρ ab +

ð ρ b Þ

χ ð Eq : 11 : 23 Þ

ρ b , 0

The density of the gas phase in the model (combination of the tars and gases, since
both are in the gas phase inside the particle during pyrolysis) is expressed in kg m gas ,

=

m particle .

while the density of the char/biomass/active biomass is expressed in kg =

The boundary conditions are as follows:

At t = 0

Initially, there is only biomass; the particle density depends on the type of biomass
and moisture content.