Ignore:
Timestamp:
Nov 3, 2009, 12:28:44 PM (13 years ago)
Author:
gerson bicca
Message:

packed column/tray revised

File:
1 edited

Legend:

Unmodified
Added
Removed
  • branches/gui/eml/stage_separators/tray.mso

    r873 r875  
    281281-------------------------------------*#
    282282Model packedStage
    283         ATTRIBUTES
     283
     284ATTRIBUTES
    284285        Pallete         = false;
    285         Icon            = "icon/PackedStage";
    286286        Brief           = "Complete model of a packed column stage.";
    287287        Info            =
     
    296296* the liquid molar holdup ML
    297297* (NoComps - 1) OutletLiquid compositions
    298 ";     
    299        
     298";
     299
    300300PARAMETERS
    301301
    302 outer PP as Plugin(Brief = "External Physical Properties", Type="PP");
    303 outer NComp as Integer;
    304 
    305         Mw(NComp)       as molweight    (Brief = "Component Mol Weight");
    306        
    307 VARIABLES
    308 
    309         Inlet                   as stream                               (Brief="Feed stream", PosX=0, PosY=0.4932, Symbol="_{in}");
    310 in      InletLiquid                     as stream                               (Brief="Inlet liquid stream", PosX=0.5195, PosY=0, Symbol="_{inL}");
    311 in      InletVapour                     as stream                               (Brief="Inlet vapour stream", PosX=0.4994, PosY=1, Symbol="_{inV}");
    312 out     OutletLiquid    as liquid_stream        (Brief="Outlet liquid stream", PosX=0.8277, PosY=1, Symbol="_{outL}");
    313 out     OutletVapour    as vapour_stream        (Brief="Outlet vapour stream", PosX=0.8043, PosY=0, Symbol="_{outV}");
    314 
    315         M(NComp) as mol (Brief="Molar Holdup in the tray", Default=0.01, Lower=0, Upper=100);
    316         ML as mol (Brief="Molar liquid holdup", Default=0.01, Lower=0, Upper=100);
    317         MV as mol (Brief="Molar vapour holdup", Default=0.01, Lower=0, Upper=100);
    318         E as energy (Brief="Total Energy Holdup on tray", Default=-500);
    319         vL as volume_mol (Brief="Liquid Molar Volume");
    320         vV as volume_mol (Brief="Vapour Molar volume");
    321        
    322         miL as viscosity (Brief="Liquid dynamic viscosity", DisplayUnit='kg/m/s');
    323         rhoL as dens_mass;
    324         rhoV as dens_mass;
    325        
    326         deltaP as pressure;
    327        
    328         uL as velocity (Brief="volume flow rate of liquid, m^3/m^2/s", Lower=-10, Upper=1000);
    329         uV as velocity (Brief="volume flow rate of vapor, m^3/m^2/s", Lower=-10, Upper=1000);
    330         Al as area (Brief="Area occupied by the liquid", Default=0.001, Upper=10);
    331         hl as positive (Brief="Column holdup", Unit='m^3/m^3', Default=0.01,Upper=10);
     302outer PP        as Plugin       (Brief = "External Physical Properties", Type="PP");
     303outer NComp as Integer  (Brief = "Number Of Components");
     304
     305        LiquidResistanceCoeff   as positive     (Brief="Resistance coefficient on the liquid load", Default=1,Hidden=true);
     306        AreaPerPackingVolume    as Real                 (Brief="surface area per packing volume", Unit='m^2/m^3',Hidden=true);
     307        ColumnInternalDiameter  as length               (Brief="Column diameter",Hidden=true);
     308        PackingVoidFraction             as Real                 (Brief="Void fraction of packing, (m^3 void space/m^3 packed bed)",Hidden=true);
     309        HeightOfPacking                 as length               (Brief="Height of packing",Hidden=true);
     310        Number_Stages                   as Integer              (Brief="Number of Stages", Default=3,Hidden=true);
     311        HeatOnStage                     as heat_rate    (Brief="Rate of heat supply",Hidden=true);
     312
     313        HETP                    as length               (Brief="The Height Equivalent to a Theoretical Plate",Hidden=true);
     314        ColumnArea              as area                 (Brief="Column Sectional Cross Area",Hidden=true);
     315        V                               as volume               (Brief="Total Volume of the tray",Hidden=true);
     316        Pi                              as constant     (Brief="Pi Number",Default=3.14159265, Symbol = "\pi",Hidden=true);
     317        Gconst                  as acceleration (Brief="Gravity Acceleration",Default=9.81,Hidden=true);
     318       
     319        low_flow                as flow_mol     (Brief ="Low Flow",Default = 1E-6, Hidden=true);
     320        low_pressure    as pressure     (Brief ="Low Pressure",Default = 1E-6, Hidden=true);
     321        zero_flow               as flow_mol     (Brief ="No Flow",Default = 0, Hidden=true);
     322
     323        Mw(NComp)       as molweight    (Brief = "Component Mol Weight",Hidden=true);
     324        VapourFlow  as Switcher         (Brief = "Vapour Flow", Valid = ["on", "off"], Default = "on",Hidden=true);
    332325
    333326SET
    334327        Mw = PP.MolecularWeight();
     328       
     329        ColumnArea      = 0.25*Pi*ColumnInternalDiameter^2;
     330        HETP            = HeightOfPacking/Number_Stages;       
     331        V                       = HETP * ColumnArea;
     332       
     333        low_pressure = 1E-4 * 'atm';
     334        low_flow = 1E-6 * 'kmol/h';
     335        zero_flow = 0 * 'kmol/h';
     336
     337VARIABLES
     338
     339        Inlet                   as stream                       (Brief="Feed stream", Symbol="_{in}",Protected=true);
     340in      InletLiquid     as stream                       (Brief="Inlet liquid stream",  Symbol="_{inL}",Protected=true);
     341in      InletVapour     as stream                       (Brief="Inlet vapour stream",  Symbol="_{inV}",Protected=true);
     342out     OutletLiquid    as liquid_stream        (Brief="Outlet liquid stream", Symbol="_{outL}",Protected=true);
     343out     OutletVapour    as vapour_stream        (Brief="Outlet vapour stream", Symbol="_{outV}",Protected=true);
     344
     345        M(NComp)        as mol                  (Brief="Molar Holdup in the tray", Default=0.01, Lower=0, Upper=100,Protected=true);
     346        ML                      as mol                  (Brief="Molar liquid holdup", Default=0.01, Lower=0, Upper=100,Protected=true);
     347        MV                      as mol                  (Brief="Molar vapour holdup", Default=0.01, Lower=0, Upper=100,Protected=true);
     348        E                       as energy               (Brief="Total Energy Holdup on tray", Default=-500,Protected=true);
     349        vL                      as volume_mol   (Brief="Liquid Molar Volume",Protected=true);
     350        vV                      as volume_mol   (Brief="Vapour Molar volume",Protected=true);
     351        miL             as viscosity    (Brief="Liquid dynamic viscosity", DisplayUnit='kg/m/s',Protected=true);
     352        rhoL            as dens_mass    (Brief="Liquid mass density",Protected=true);
     353        rhoV            as dens_mass    (Brief="Vapour mass density",Protected=true);
     354        uL                      as velocity     (Brief="volume flow rate of liquid, m^3/m^2/s", Lower=-10, Upper=1000,Protected=true);
     355        uV                      as velocity     (Brief="volume flow rate of vapor, m^3/m^2/s", Lower=-10, Upper=1000,Protected=true);
     356        Al                      as area                 (Brief="Area occupied by the liquid", Default=0.001, Upper=10,Protected=true);
     357        hl                      as positive     (Brief="Column holdup", Unit='m^3/m^3', Default=0.01,Upper=10,Protected=true);
     358        deltaP          as pressure     (Brief="Stage Pressure drop",Protected=true);
    335359
    336360EQUATIONS
     361
     362switch VapourFlow
     363       
     364        case "on":
     365"Pressure drop and Vapor flow, Billet (4-58)"
     366        deltaP/HETP  = LiquidResistanceCoeff *( 0.5*AreaPerPackingVolume + 2/ColumnInternalDiameter) * 1/((PackingVoidFraction-hl)^3) * (uV^2) *rhoV;
     367       
     368        when InletVapour.F < low_flow switchto "off";
     369       
     370        case "off":
     371"Vapour Flow"
     372        InletVapour.F = zero_flow;
     373       
     374        when deltaP > low_pressure switchto "on";
     375
     376end
     377
     378"Energy Balance"
     379        diff(E) = (Inlet.F*Inlet.h + InletLiquid.F*InletLiquid.h + InletVapour.F*InletVapour.h- OutletLiquid.F*OutletLiquid.h
     380        - OutletVapour.F*OutletVapour.h + HeatOnStage );
     381
     382"Energy Holdup"
     383        E = ML*OutletLiquid.h + MV*OutletVapour.h - OutletLiquid.P*V;
     384
     385"Geometry Constraint"
     386        V*PackingVoidFraction= ML*vL + MV*vV;
     387
     388"Volume flow rate of vapor, m^3/m^2/s"
     389        uV * (V*PackingVoidFraction/HETP - Al) = InletVapour.F * vV;
     390
     391"Liquid holdup"
     392        hl*V*PackingVoidFraction = ML*vL;
     393
     394"Liquid velocity as a function of liquid holdup, Billet (4-27)"
     395        hl^3 = (12/Gconst) * AreaPerPackingVolume^2 * (miL/rhoL) * uL;
     396
     397"Area occupied by the liquid"
     398        Al = ML*vL/HETP;
    337399
    338400"Component Molar Balance"
     
    341403"Molar Holdup"
    342404        M = ML*OutletLiquid.z + MV*OutletVapour.z;
    343        
     405
    344406"Mol Fraction Normalisation"
    345407        sum(OutletLiquid.z)= 1.0;
     
    376438       
    377439"Pressure Drop"
    378         deltaP = InletVapour.P - OutletVapour.P;
     440        deltaP = InletVapour.P - OutletVapour.P;       
    379441
    380442end
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