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2.830J / 6.780J / ESD.63J Control of Manufacturing Processes (SMA 6303)
Spring 2008
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2007518
2.830
Control
of
Manufacturing
Systems
Final
Project
Profit
Maximization
in
Ethanol
Production
(May
2007)
R.
Sriram,
S.
Subramanian,
and
G.
Tomlin
Abstract
 We
document
an
experimental
study
to
optimize
yield
of
an
ethanol
distillation
process.
The
yield
is
expressed
in
terms
of
concentration
of
the
ethanol
obtained,
and
the
profit
from
the
process.
Concentration
is
a
function
of
six
input
factors
that
can
be
varied
within
a
given
range.
Profit
is
a
function
of
the
revenue
(which
depends
on
the
concentration
of
ethanol
achieved)
and
costs
(which
vary
with
the
input
factor
settings).
We
started
by
determining
a
practical
operating
range
for
the
six
input
parameters
where
the
constraints
of
the
system
(pressure
in
the
distillation
column
and
holding
tanks)
were
not
violated.
We
then
conducted
a
factorial
experimental
analysis
and
used
a
response
surface
method
(path
of
steepest
ascent)
to
determine
an
operating
point
where
the
desired
concentration
level
is
achieved.
Finally,
we
used
a
space
filling
experimental
design
in
a
narrow
region
around
the
operating
point
to
determine
the
effect
of
various
input
parameters
on
robustness
and
profit.
Index
Terms
—Ethanol,
Design
of
Experiments,
Optimization
O
I.
PROBLEM
DEFINITION
ur
team
found
a
distillation
simulator
[2]
that
was
used
as
the
basis
of
a
project
at
Virginia
Tech.
This
simulator
can
be
found
at
www.stat.vt.edu/~vining
.
The
simulator
takes
an
input
of
6
factors
and
gives
outputs
of
concentration,
profit
and
pressure.
The
objective
is
to
maximize
profit
by
changing
the
six
factors.
The
six
factors
are:
Feed
Rate
(gallons
per
minute)
Feed
Temperature
(Fahrenheit)
Distillate
Rate
(gallons
per
minute)
Condensate
Temperature
(Fahrenheit)
Reboil
Temperature
(Fahrenheit)
Reflux
ratio
(percent)
Having
no
knowledge
of
the
operating
conditions,
we
were
provided
with
costs,
revenues,
and
constraints.
This
gave
us
a
basic
understanding
of
the
premise,
and
we
were
able
to
use
given
pilot
values
as
a
starting
point
for
our
analysis.
The
given
costs
are:
Fixed
Costs
$1,000
per
run
Heating
Costs
$0.08
/
100,000
Btu
Cooling
Costs
$0.04
/
100,000
Btu
Raw
Material
Costs
$0.015
/
gallon
The
given
revenue
is:
concentration
<
80%
=
$
0
80%<
concentration
<
90%
=
$
.50/gallon
90%<
concentration
<
95%
=
$1.00/gallon
95%<
concentration
<
100%
=
$1.25/gallon
Constraints
given
are
pressure
limits.
If
maximum
pressure
is
exceeded
then
the
process
fails,
no
product
is
made
and
repair
costs
are
extraordinary.
II.
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This note was uploaded on 09/24/2010 for the course MECHE 2.830J taught by Professor Davidhardt during the Spring '08 term at MIT.
 Spring '08
 DavidHardt

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