Transcript CHEMCAD Distillation

CHEMCAD Distillation
David Weglein
Savannah Green
Heather Cook
Michael Wellen
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What if…
•
You have a Japanese client working in Yen, who liked everything about the metric scale
except length measurements, thinks the Rankine scale is underrated, and likes his vapor
density in lb/ft3
•
No problem!
Checklist
Choosing a Thermodynamic Model
Recommendations
Gas Phase Only
Ideal Solution
Non-ideal Solution
Checking Equilibrium Data
CHEMCAD Distillation Columns
• 4 types of columns, differ in:
– What algorithm they use
– What information load they can handle
– What parameters you can find from simulation
#1 – Shortcut Column
• Uses Fenske-Underwood
method
• One feed, bottoms and
distillate
• Typically used as a way to
get rough estimates
– Reboiler/condenser duties,
number of theoretical
stages, optimum feed
location, fractional
recoveries.
• Industrial users will
(should) not use this one
#2 - SCDS
• Simultaneous Correction
Distillation System
– Uses a “simultaneous correction”
algorithm
• Can do reactive distillation, mass
transfer distillation (packing)
• Stable with non-ideal
thermodynamics
• Handles a large number of stages
• Multiple feeds, side stream
possible
• In addition to what the SHOR
column can do, can also do mass
transfer and tray efficiency
• Commonly used
#3 - Tower
• “Inside-out algorithm”
• Used for large number of
components, small
number of stages
• Can do dynamic (nonsteady-state) simulations
• No efficiencies, mass
transfer, or reactive
distillation
• Used more for
hydrocarbons
#4 – Tower+
• Used for crude oil
• Complex columns
Recommendations
Demo