1 | #*------------------------------------------------------------------- |
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2 | * EMSO Model Library (EML) Copyright (C) 2004 - 2007 ALSOC. |
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3 | * |
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4 | * This LIBRARY is free software; you can distribute it and/or modify |
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5 | * it under the therms of the ALSOC FREE LICENSE as available at |
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6 | * http://www.enq.ufrgs.br/alsoc. |
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7 | * |
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8 | * EMSO Copyright (C) 2004 - 2007 ALSOC, original code |
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9 | * from http://www.rps.eng.br Copyright (C) 2002-2004. |
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10 | * All rights reserved. |
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11 | * |
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12 | * EMSO is distributed under the therms of the ALSOC LICENSE as |
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13 | * available at http://www.enq.ufrgs.br/alsoc. |
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14 | * |
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15 | *------------------------------------------------------------------- |
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16 | * Model of a static PH flash |
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17 | *-------------------------------------------------------------------- |
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18 | * - Streams |
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19 | * * a liquid outlet stream |
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20 | * * a vapour outlet stream |
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21 | * * a feed stream |
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22 | * |
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23 | * - Assumptions |
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24 | * * both phases are perfectly mixed |
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25 | * |
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26 | * - Specify: |
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27 | * * the feed stream; |
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28 | * * the heat duty |
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29 | * * the outlet pressure |
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30 | * |
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31 | *---------------------------------------------------------------------- |
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32 | * Author: Rafael de P. Soares and Paula B. Staudt |
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33 | * $Id: flashPH.mso 97 2007-01-03 13:31:49Z rafael $ |
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34 | *--------------------------------------------------------------------*# |
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35 | |
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36 | using "streams"; |
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37 | |
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38 | Model FlashPHSteady |
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39 | PARAMETERS |
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40 | ext PP as CalcObject; |
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41 | ext NComp as Integer; |
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42 | B as Real(Default=1000, Brief="Regularization Factor"); |
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43 | |
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44 | VARIABLES |
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45 | in Inlet as stream; #(Brief="Feed Stream"); |
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46 | out OutletL as stream_therm; #(Brief="Liquid outlet stream"); |
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47 | out OutletV as stream_therm; #(Brief="Vapour outlet stream"); |
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48 | in Q as heat_rate (Brief="Rate of heat supply"); |
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49 | vfrac as fraction(Brief="Real vaporization fraction"); |
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50 | vsat as Real(Lower=-1, Upper=2, Brief="Vaporization fraction if saturated"); |
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51 | Tsat as temperature(Lower=173, Upper=473, Brief="Temperature if saturated"); |
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52 | xsat(NComp) as Real(Lower=-5, Upper=5, Brief="Liquid composition if saturated"); |
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53 | ysat(NComp) as Real(Lower=-5, Upper=5, Brief="Vapour composition if saturated"); |
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54 | |
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55 | zero_one as fraction(Brief="Regularization Variable"); |
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56 | one_zero as fraction(Brief="Regularization Variable"); |
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57 | |
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58 | EQUATIONS |
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59 | "Chemical equilibrium" |
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60 | PP.LiquidFugacityCoefficient(Tsat, OutletL.P, OutletL.z)*xsat = |
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61 | PP.VapourFugacityCoefficient(Tsat, OutletV.P, OutletV.z)*ysat; |
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62 | |
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63 | "Global Molar Balance" |
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64 | Inlet.F = OutletV.F + OutletL.F; |
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65 | OutletV.F = Inlet.F * vfrac; |
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66 | |
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67 | "Component Molar Balance" |
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68 | Inlet.F*Inlet.z = OutletL.F*xsat + OutletV.F*ysat; |
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69 | sum(xsat) = sum(ysat); |
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70 | |
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71 | "Energy Balance if saturated" |
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72 | Inlet.F*Inlet.h + Q = |
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73 | Inlet.F*(1-vsat)*PP.LiquidEnthalpy(Tsat, OutletL.P, OutletL.z) + |
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74 | Inlet.F*vsat*PP.VapourEnthalpy(Tsat, OutletV.P, OutletV.z); |
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75 | |
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76 | "Real Energy Balance" |
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77 | Inlet.F*Inlet.h + Q = |
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78 | Inlet.F*(1-vfrac)*OutletL.h + Inlet.F*vfrac*OutletV.h; |
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79 | |
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80 | "Thermal Equilibrium" |
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81 | OutletV.T = OutletL.T; |
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82 | |
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83 | "Mechanical Equilibrium" |
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84 | OutletV.P = OutletL.P; |
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85 | |
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86 | "vaporization fraction " |
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87 | OutletV.v = 1.0; |
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88 | "vaporization fraction " |
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89 | OutletL.v = 0.0; |
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90 | |
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91 | # regularization functions |
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92 | zero_one = (1 + tanh(B * vsat))/2; |
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93 | one_zero = (1 - tanh(B * (vsat - 1)))/2; |
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94 | |
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95 | vfrac = zero_one * one_zero * vsat + 1 - one_zero; |
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96 | OutletL.z = zero_one*one_zero*xsat + (1-zero_one*one_zero)*Inlet.z; |
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97 | OutletV.z = zero_one*one_zero*ysat + (1-zero_one*one_zero)*Inlet.z; |
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98 | end |
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