ned
Daop
Date
Expt.No.
SIMPLE
DISTILLATION
AIM
To
verify
the
Rayleigh's
equation for
simple
distillation.
APPARATUS
Measuring
jar,
specific
gravity
bottle,
weight
box
THEORY
Simple disti|lation
is
the
process
consisting of infinite
number
of
successive
steps
of
flash
vaporization.
Where
in
each
step,
an
infinite small portion of liquid is
vaporized
and
the
resulting
vapour
that
is
in
equlibrium
with
the
liquid
is
removed.
Simple distillation is a
batch
operation.
This
operation
is
used
to
separate
liquid
whose
components have
fairily
large
difference
in
their
boiling
points.
This
type
of
distillation
is
frequently
employed
in
laboratory
and
in
pilot plants to
concentrate
one
component
in
the
distillate
or
residue.
It
is
also
used
for
analytical
evaluation
of
boiling
range
of
mixtures.
Rayleigh
developed
a
mathematica!
equation
for
simple
distillation,
which
is
given
by
dx
where
F
Kg
moles
of
feed
W =
Kg
moles
of
residue
X
mole
fraction
of
more
volatile
component
in
feed
X
mole
fraction
of
more
volatile component
in
the
residue
y =
equilibrium
mole
fraction
of
more
volatile
component
in
vapour
x=
equilibrium
mole
fraction
of
more
volatile
component
in
liquid.
Rayeigh's equation holds well
under
the
following
assumptions
.he
composition
of
liquid
is
uniform
2.
The
process
is
carried
out
slowly,
so
that
vapours
leaving
the
stll
are
in
equilibrium
with
the
liquid
in
the
still
3.
There
is
no
entrainment of the liquid.
Gre
is
no
condensation
of
the
vapour
betore
it
reaches
the
condensor.
For an ideal
svstem,
relative volatility a is
constant
and
Rayleigh's
equation
gives,
Ther
F(1-x)
Fxf
gvc
In(1-X,
In
WXw
