SME
Process Design
Process economics
Use this for “A 100 m² heat exchanger cost $80,000 when the CEPCI was 550.8. What does a 250 m² one cost now, at an index of 800?”
Chart
C(250) ≈ 201,300
This is an example. Type your own values to start a new problem.
$
C₂
=
$
C₁
×
(
S₂ (m²)
÷
S₁ (m²)
)
×
(
I₂
÷
I₁
)
Formulas
C₂
=
C₁
×
(
S₂
S₁
)
n
×
(
I₂
I₁
)
201,349
=
80,000
×
(
250
100
)
0.6
×
(
800
550.8
)
Assumptions
•
Same equipment type and material, so one cost exponent n holds; 0.6 when none is given (the six-tenths rule).
•
The two sizes are within about a factor of 10 of each other.
•
Index values are typed from the published CEPCI (Chemical Engineering Plant Cost Index) for each year.
Step-by-step
WE KNOW
C₁ = $80,000, S₁ = 100 m², S₂ = 250 m², n = 0.6, I₁ = 550.8, I₂ = 800
FIND
new cost (C₂)
Step 1 · Find new cost (C₂)
Use C₂ = C₁ × (S₂ ÷ S₁)ⁿ × (I₂ ÷ I₁)
Scale
the
base
cost
by
the
size
ratio
to
the
power
n
,
then
bring
it
to
today
by
the
ratio
of
the
indexes.
C₂
=
80,000
×
(
250
100
)
0.6
×
(
800
550.8
)
C₂
=
80,000
×
2.5
0.6
×
1.4524
C₂
=
80,000
×
1.7329
×
1.4524
80,000
×
(
250
100
)
0.6
×
(
800
550.8
)
=
201,349.2645
C₂
=
about
$201,349
Check
Put the numbers back in. Both sides should match.
201,349
=
80,000
×
(
250
100
)
0.6
×
(
800
550.8
)
✓
Topic check
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