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

The maximum height that a large particle can reach is
z
's vsi
Hmax = 2(Ps - Pg)g
for descending particles
v S =- J-) =
Since the local velocity of each particle is obtained in analytic form, the particle
density (Equation 12) yields a closed-form expression:
(Large particles
P(Z) = 2(1-Yc)Eo fidvsi not elutriacted)
J
I
(1-y )E f.dv (Large particles
c 0 1 si
elutriated)
2
vsi -2€!Z(Ps-Pg)/Ps
(Small particles
18)
elutriated)
I > y(d )
YC
where u (d ) < u is the mass fraction of small particles, and fi d vsi
t Pi g
represents the mass fraction of particles with an initial velocity between v andv .
s1
+ dv .. The validity of the approximations made in simplifying the nodel wasSi
s1
by comparing the particle censities predicted by the two methods (15). The
maximum discrepancy was less than 30% of the particle density predicted by the complete
model, and the significant features of both density profiles were identical.
The results presented here were obtained using the simpler model.
Two Component Bed
When the bed :,as two components, for example a very small amount of char mixed
with stone, the initial entrainment of the char, Eo , is a small fraction of the
total initial entrainment. Assuming that the stratification factor is equal to the
density ratio.
The initial velocity distribution for the char is the same as €or the stone, and the
total char density is found by the same procedure as before, with p in place
s ,c
of Ps.
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