the coking properties of coal at elevated pressures. - Argonne ...

R =
K KD C
Kc + KD
where % = -k x
1
Kc = -k2x 2
(See equations 28) and 31) for values of kl and k2)) C is the oxygen
concentration (moles/m3) in the particulate phase of tge bed and is a function
of time.
by
The rate of consumption of carbon at the particle surface is therefore given
3
-k k X- Mo C
5 = 1 2 p
2
dt k x + k x
I P 2P
leading to
dx -2M C
p = OP
dt TP
where x is the diameter of a particle of mass m and M is the molecular weight
of oxyggn. P
klandf = - 1
For convenience let F(C) = 2M C , e = -
op 2 kl
TP
If after a time t a particle whose original diameter was x bums to give
a diameter xt, then
t
t f
Let the original size distribution of a batch of carbon delivered to the
fluidised bed be given by an equation of the form.
w. = e(x) 7)
where W. is the initial weight of the batch which consists of particles whose
diamete? is greater than or equal to X. It will be assumed that x must lie in
the range x1