Distillation : McCabe-Thiele
Method
Description:
Calculates distillation parameters per the McCabe-Thiele method as indicated
in the reference below. User must input a relative volatility for the most
volatile component. The equilibrium curve is generated per this value. The
relative volatility is assumed to be constant throughout all concentrations
(mole fractions).
Alternative Descriptors:
Binary Distillation Modeling, McCabe Thiele distillation modeling.
Calc Number:
DS-MCCSMI-0031
Calc Status:
Beta
Reference:
Unit Operations of Chemical Engineering, Third Edition, McCabe and Smith,
pgs. 551-563
Reference Example(s) Modeled/Generalized:
Calc Origination Date:
04/04/2006
Calc Originator:
RBC
Calc Revision History:
Calc Guidelines:
See the above reference
Access:
Activating this calc requires entry of the correct access code. Contact
[email protected]
Variables:
Variable Description - Description of the variable
Variable Label Description - The description of the variable as it appears in
the calc.
Variable Calc Name - The calc internal variable name
Variable Units - The units for the variable
Variable Calc Upper Limit - The highest allowed value in the calc.
Variable Calc Lower Limit - The lowest allowed value in the calc.
Variable Type - Either "Output" or "Input"
Variable Format - Real Number, Text, or Integer
Variable Notes - Other comments about the variable
Variable Description:
Number of Ideal (100% tray efficiency) Stages required to achieve
separation.
Variable Label
Description: Number of Stages Required
Variable Calc Name:
NST
Variable Units:
Variable Calc Upper
Limit: 1000
Variable Calc Lower
Limit: 1
Variable Type:
Output
Variable Format:
REAL
Variable Notes:
Variable Description:
Number of Stages Between Reboiler and Feed counting the reboiler.
Variable Label
Description: Stages Between Reboiler and Feed Stage
Variable Calc Name:
LOS
Variable Units:
Variable Calc Upper
Limit: 1000
Variable Calc Lower
Limit: 1
Variable Type:
Output
Variable Format:
REAL
Variable Notes:
Variable Description:
Number of Stages Between Feed and Condenser.
Variable Label
Description: Stages Between Feed Stage and Condenser
Variable Calc Name:
HOS
Variable Units:
Variable Calc Upper
Limit: 1000
Variable Calc Lower
Limit: 1
Variable Type:
Output
Variable Format:
REAL
Variable Notes:
Variable Description:
External Reflux Ratio (Mole Basis) specified by user, Distillate returned to
column divided by Distillate exiting column
Variable Label
Description: Specified External Reflux Ratio
Variable Calc Name:
ERR
Variable Units:
Variable Calc Upper
Limit: 1000
Variable Calc Lower
Limit: 0.0001
Variable Type:
Output
Variable Format:
REAL
Variable Notes: If
minimum reflux ratio is determined to be negative, then the value of 0.01 is
used as the external reflux ratio.
Variable Description:
Minimum External Reflux Ratio to achieve the required separation (Mole
Basis)
Variable Label
Description: Minimum External Reflux Ratio
Variable Calc Name:
MRR
Variable Units:
Variable Calc Upper
Limit: 1000
Variable Calc Lower
Limit: 0.0001
Variable Type:
Output
Variable Format:
REAL
Variable Notes:
Variable Description:
Minimum number of stages, at total reflux, to achieve required separation
Variable Label
Description: Total Reflux Stages
Variable Calc Name:
STR
Variable Units:
Variable Calc Upper
Limit: 1000
Variable Calc Lower
Limit: 0.0001
Variable Type:
Output
Variable Format:
REAL
Variable Notes:
Variable Description:
Ratio of Distillate Flow to Feed Flow (Mole Basis)
Variable Label
Description: Ratio of Distillate Flow to Feed Flow
Variable Calc Name:
DFR
Variable Units:
Variable Calc Upper
Limit: 0.9999
Variable Calc Lower
Limit: 0.0001
Variable Type:
Output
Variable Format:
REAL
Variable Notes:
Variable Description:
Ratio of Bottoms Flow to Feed Flow (Mole Basis)
Variable Label
Description: Ratio of Bottoms Flow to Feed Flow
Variable Calc Name:
BFR
Variable Units:
Variable Calc Upper
Limit: 0.9999
Variable Calc Lower
Limit: 0.0001
Variable Type:
Output
Variable Format:
REAL
Variable Notes:
Variable Description:
Comments
Variable Label
Description: Comments
Variable Calc Name:
COM
Variable Units:
Variable Calc Upper
Limit:
Variable Calc Lower
Limit:
Variable Type:
Output
Variable Format:
TEXT
Variable Notes:
Displays "Input(s) out of range." if an entered input variable(s) are out of
range. Displays "Output(s) out of range." if an output variable exceeds its
range. The "out of range" variable(s) are displayed in
yellow. The limited range values are used in the calculation, not the
"out of range" value(s).
Variable Description:
Mole fraction of more volatile component at the bottoms discharge of the
distillation column
Variable Label
Description: Bottoms Mole Fraction
Variable Calc Name:
BMF
Variable Units:
Variable Calc Upper
Limit: 0.9999
Variable Calc Lower
Limit: 0.0001
Variable Type:
Input
Variable Format:
REAL
Variable Notes:
Variable Description:
Mole fraction of more volatile component at the top discharge of the
distillation column
Variable Label
Description: Top Mole Fraction
Variable Calc Name:
TMF
Variable Units:
Variable Calc Upper
Limit: 0.9999
Variable Calc Lower
Limit: 0.0001
Variable Type:
Input
Variable Format:
REAL
Variable Notes:
Variable Description:
Ratio (Relative Volatility) of Equilibrium Constant (K Value) of more
volatile component (light key) to K value of less volatile component (heavy
key).
Variable Label
Description: Relative Volatility of Light Key
Variable Calc Name:
RVO
Variable Units:
Variable Calc Upper
Limit: 1000
Variable Calc Lower
Limit: 0.001
Variable Type:
Input
Variable Format:
REAL
Variable Notes:
Variable Description:
Desired Reflux Ratio divided by the Minimum Reflux Ratio
Variable Label
Description: Reflux Ratio Factor
Variable Calc Name:
RRA
Variable Units:
Variable Calc Upper
Limit: 10
Variable Calc Lower
Limit: 1
Variable Type:
Input
Variable Format:
REAL
Variable Notes: The
calc first determines the minimum reflux ratio for the system. The calc uses the
minimum reflux ratio times the Reflux Ratio Factor as the external reflux ratio.
If minimum reflux ratio is determined to be negative, then the value of 0.01 is
used for the external reflux ratio.
Variable Description:
Mole fraction of more volatile component in the feed
Variable Label
Description: Feed Mole Fraction
Variable Calc Name:
FMF
Variable Units:
Variable Calc Upper
Limit: 0.9999
Variable Calc Lower
Limit: 0.0001
Variable Type:
Input
Variable Format:
REAL
Variable Notes:
Variable Description:
State of feed measured as ratio of heat required to convert one mole of feed
to vapor to molar heat of vaporization of feed. FQ = 1 is saturated liquid feed.
FQ=0 is saturate vapor feed.
Variable Label
Description: Q Value of Feed
Variable Calc Name:
FQ
Variable Units:
Variable Calc Upper
Limit: 1
Variable Calc Lower
Limit: 0
Variable Type:
Input
Variable Format:
REAL
Variable Notes:
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