Changeset 848 for trunk/eml


Ignore:
Timestamp:
Oct 3, 2009, 7:15:28 PM (13 years ago)
Author:
Rafael de Pelegrini Soares
Message:

Improved packed column models

Location:
trunk/eml/stage_separators
Files:
2 edited

Legend:

Unmodified
Added
Removed
  • trunk/eml/stage_separators/column.mso

    r511 r848  
    13081308       
    13091309        EQUATIONS
    1310         stage.deltaP = dP/NStages;
     1310        #stage.deltaP = dP/NStages;
     1311        dP = stage(bot).OutletL.P - stage(top).OutletL.P;
    13111312       
    13121313        CONNECTIONS
     
    13521353";
    13531354       
    1354         PARAMETERS
    1355         VapourFlow as Switcher(Valid = ["on", "off"], Default = "on");
    1356        
    13571355        VARIABLES
    13581356        cond as condenser;
     
    13731371       
    13741372        EQUATIONS
    1375         switch VapourFlow
    1376                 case "on":
    1377                 stage(bot).InletV.F*stage(bot).vV = sqrt((reb.OutletV.P - stage(bot).OutletV.P)/
    1378                                         (stage(bot).rhoV*stage(bot).Qsil*20))*(stage(bot).d^2*3.14159/4*stage(bot).e - stage(bot).Al);
    1379                 when stage(bot).InletV.F < 1e-6 * 'kmol/h' switchto "off";
    1380                
    1381                 case "off":
    1382                 stage(bot).InletV.F = 0 * 'mol/s';
    1383                 when reb.OutletV.P > stage(bot).OutletV.P + 1e-1 * 'atm' switchto "on";
    1384         end
    1385 
    1386 end
     1373        stage(top).InletV.F = stage(top).OutletV.F + stage(top).Inlet.F*stage(top).Inlet.v;
     1374
     1375end
  • trunk/eml/stage_separators/tray.mso

    r706 r848  
    405405outer PP as Plugin(Brief = "External Physical Properties", Type="PP");
    406406outer NComp as Integer;
    407         PPwater as Plugin(Brief="Physical Properties",
    408                 Type="PP",
    409                 Components = [ "water" ],
    410                 LiquidModel = "PR",
    411                 VapourModel = "PR"
    412         );
    413407
    414408        V as volume(Brief="Total Volume of the tray");
     
    419413        g as acceleration;
    420414        e as Real (Brief="Void fraction of packing, m^3/m^3");
    421         Cpo as Real (Brief="Constant for resitance equation"); # Billet and Schultes, 1999.
    422415        Mw(NComp)       as molweight    (Brief = "Component Mol Weight");
    423416        hs as length (Brief="Height of the packing stage");
    424         Qsil as positive (Brief="Resistance coefficient on the liquid load", Default=1);
     417        Qsil as positive (Brief="Resistance coefficient on the liquid load", Default=0.6);
     418
     419        VapourFlow as Switcher(Valid = ["on", "off"], Default = "on");
    425420
    426421        VARIABLES
     
    439434       
    440435        miL as viscosity (Brief="Liquid dynamic viscosity", DisplayUnit='kg/m/s');
    441         miV as viscosity (Brief="Vapor dynamic viscosity", DisplayUnit='kg/m/s');
    442436        rhoL as dens_mass;
    443437        rhoV as dens_mass;
    444438       
    445         deltaP as pressure;
    446        
    447         uL as velocity (Brief="volume flow rate of liquid, m^3/m^2/s", Lower=-10, Upper=100);
    448         uV as velocity (Brief="volume flow rate of vapor, m^3/m^2/s", Lower=-10, Upper=100);
    449         dp as length (Brief="Particle diameter", Default=1e-3, Lower=0, Upper=10);
    450         invK as positive (Brief="Wall factor", Default=1, Upper=10);
    451         Rev as Real (Brief="Reynolds number of the vapor stream", Default=4000);
    452         Al as area (Brief="Area occupied by the liquid", Default=0.001, Upper=1);
    453         hl as positive (Brief="Column holdup", Unit='m^3/m^3', Default=0.01,Upper=10);
    454 
     439        deltaP as pressure(Lower=-10);
     440       
     441        uL as velocity (Brief="volume flow rate of liquid, m^3/m^2/s", Lower=0, Upper=100);
     442        uV as velocity (Brief="volume flow rate of vapor, m^3/m^2/s", Lower=0, Upper=100);
     443        Al as area (Brief="Area occupied by the liquid", Default=0.001, Upper=10);
     444        hl as positive (Brief="Column holdup", Unit='m^3/m^3', Default=0.04,Upper=1);
     445       
    455446        SET
    456447        Mw = PP.MolecularWeight();
     
    473464        "Mol fraction normalisation"
    474465        sum(OutletL.z)= 1.0;
    475        
     466        sum(OutletL.z)=sum(OutletV.z);
     467
    476468        "Liquid Volume"
    477469        vL = PP.LiquidVolume(OutletL.T, OutletL.P, OutletL.z);
     
    498490        "Liquid viscosity"
    499491        miL = PP.LiquidViscosity(OutletL.T, OutletL.P, OutletL.z);
    500         "Vapour viscosity"
    501         miV = PP.VapourViscosity(InletV.T, InletV.P, InletV.z);
    502492
    503493        "Area occupied by the liquid"
     
    507497        uL * Al = OutletL.F * vL;
    508498        "Volume flow rate of vapor, m^3/m^2/s"
    509         uV * ((d^2*3.14159/4)*e - Al) = OutletV.F * vV;
     499        uV * (V*e/hs - Al) = InletV.F * vV;
    510500       
    511501        "Liquid holdup"
    512         hl = ML*vL/V/e;
    513        
    514         "Particle diameter"
    515         dp = 6 * (1-e)/a;
    516        
    517         "Wall Factor"
    518         invK = (1 + (2*dp/(3*d*(1-e))));
    519        
    520         "Reynolds number of the vapor stream"
    521         Rev*invK = dp*uV*rhoV / (miV*(1-e));
    522        
     502        hl*V*e = ML*vL;
     503       
     504        "Liquid velocity as a function of liquid holdup, Billet (4-27)"
     505        hl^3 = (12/g) * a^2 * (miL/rhoL) * uL;
     506       
     507        switch VapourFlow
     508                case "on":
     509                "Pressure drop and Vapor flow, Billet (4-58)"
     510                deltaP/hs  = Qsil * (a/2 + 2/d) * 1/((e-hl)^3) * (uV^2) * rhoV;
     511               
     512                when InletV.F < 1e-6 * 'kmol/h' switchto "off";
     513               
     514                case "off":
     515                InletV.F = 0 * 'mol/s';
     516                when deltaP > 1e-4 * 'atm' switchto "on";
     517        end
     518
     519        "Pressure profile"
    523520        deltaP = InletV.P - OutletV.P;
    524        
    525         "Pressure drop and Vapor flow"
    526         deltaP/hs  = Qsil*a*uV^2*rhoV*invK / (2*(e-hl)^3);
    527 
    528         "Liquid holdup"
    529         hl = (12*miL*a^2*uL/rhoL/g)^1/3;
    530521end
    531522
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