source: mso/eml/stage_separators/batch_dist.mso @ 68

#*-------------------------------------------------------------------
* Model of a Batch Distillation (or Differential Distilation)
*-------------------------------------------------------------------- 
*
*       Streams:
*               * a liquid inlet stream
*               * a vapour outlet stream
*               * a inlet stream
*
*       Assumptions:
*               * perfect mixing of both phases
*               * thermodynamics equilibrium
*               * no liquid entrainment in the vapour stream
*
*       Specify:
*               * the inlet stream
*               * the liquid inlet stream
*               * the molar flow of the vapour outlet stream
*
*       Initial:
*               * the distillator temperature (T)
*               * the distillator liquid level (Ll)
*               * (NoComps - 1) compositions in the distillator
*                                       or in the OutletV
*               
*
*----------------------------------------------------------------------
* Author: Maurício Carvalho Maciel
* $Id: batch_dist.mso 1 2006-06-20 17:33:53Z rafael $
*--------------------------------------------------------------------*#
using "streams";
        
Model Diff_Dist
        
        PARAMETERS
ext PP          as CalcObject   (Brief = "External Physical Properties");
ext NComp       as Integer              (Brief = "Number of chemical components", Lower = 1);
        Across  as area                 (Brief="Cross Section Area");
        V               as volume               (Brief="Total volume");
        
        VARIABLES
in      Inlet   as stream;              #(Brief="Feed stream");
in      InletL  as stream;              #(Brief="Liquid inlet stream");
out     OutletV as stream_therm; #(Brief="Vapour outlet stream");

        M(NComp)        as mol                  (Brief="Molar Holdup in the distillator");
        ML                      as mol                  (Brief="Molar liquid holdup");
        MV                      as mol                  (Brief="Molar vapour holdup");
        E                       as energy               (Brief="Total Energy holdup on distillator");
        volL            as volume_mol   (Brief="Liquid Molar Volume");
        volV            as volume_mol   (Brief="Vapour Molar volume");
        Level           as length               (Brief="Level of liquid phase", Default=1, Lower=0);
        T                       as temperature  (Brief="Temperature on distillator");
        P                       as pressure             (Brief="Pressure on distillator");
        x(NComp)        as fraction     (Brief = "Molar Fraction of the Liquid of the distillator");
        h                       as enth_mol             (Brief="Molar Enthalpy of the liquid of the distillator");
        Q                       as heat_rate    (Brief="Heat supplied");
        
        EQUATIONS
        
        "Component Molar Balance"
        diff(M)= Inlet.F*Inlet.z + InletL.F*InletL.z - OutletV.F*OutletV.z;
        
        "Energy Balance"
        diff(E) = Inlet.F*Inlet.h + InletL.F*InletL.h - OutletV.F*OutletV.h + Q;
        
        "Molar Holdup"
        M = ML*x + MV*OutletV.z; 
        
        "Energy Holdup"
        E = ML*h + MV*OutletV.h - P*V;
        
        "Mol fraction normalisation"
        sum(x)=1.0;
        sum(x)=sum(OutletV.z);

        "Liquid Volume"
        volL = PP.LiquidVolume(T, P, x);
        
        "Vapour Volume"
        volV = PP.VapourVolume(OutletV.T, OutletV.P, OutletV.z);
        
        "Chemical Equilibrium"
        PP.LiquidFugacityCoefficient(T, P, x)*x = 
                PP.VapourFugacityCoefficient(OutletV.T, OutletV.P, OutletV.z)*OutletV.z;

        "Mechanical Equilibrium"
        P = OutletV.P;
        
        "Thermal Equilibrium"
        T = OutletV.T;
        
        "Geometry Constraint"
        V = ML*volL + MV*volV;
        
        "Level of liquid phase"
        Level = ML*volL/Across;
        
        "vaporization fraction "
        OutletV.v = 1.0;
        
        "Enthalpy"
        h = PP.LiquidEnthalpy(T, P, x);
        
end