Title and Link to Calc:

Distillation : McCabe-Thiele Method : DS-MCCSMI-0031

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 eng-calc@eng-calcs.com

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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