1 | #*------------------------------------------------------------------- |
---|
2 | * EMSO Model Library (EML) Copyright (C) 2004 - 2007 ALSOC. |
---|
3 | * |
---|
4 | * This LIBRARY is free software; you can distribute it and/or modify |
---|
5 | * it under the therms of the ALSOC FREE LICENSE as available at |
---|
6 | * http://www.enq.ufrgs.br/alsoc. |
---|
7 | * |
---|
8 | * EMSO Copyright (C) 2004 - 2007 ALSOC, original code |
---|
9 | * from http://www.rps.eng.br Copyright (C) 2002-2004. |
---|
10 | * All rights reserved. |
---|
11 | * |
---|
12 | * EMSO is distributed under the therms of the ALSOC LICENSE as |
---|
13 | * available at http://www.enq.ufrgs.br/alsoc. |
---|
14 | *---------------------------------------------------------------------- |
---|
15 | * Author: Paula B. Staudt |
---|
16 | * $Id: flash.mso 372 2007-09-21 22:17:36Z arge $ |
---|
17 | *--------------------------------------------------------------------*# |
---|
18 | |
---|
19 | using "streams"; |
---|
20 | |
---|
21 | Model flash |
---|
22 | ATTRIBUTES |
---|
23 | Pallete = true; |
---|
24 | Icon = "icon/Flash"; |
---|
25 | Brief = "Model of a dynamic flash."; |
---|
26 | Info = |
---|
27 | "== Assumptions == |
---|
28 | * both phases are perfectly mixed. |
---|
29 | |
---|
30 | == Specify == |
---|
31 | * the feed stream; |
---|
32 | * the outlet flows: OutletV.F and OutletL.F. |
---|
33 | |
---|
34 | == Initial Conditions == |
---|
35 | * the flash initial temperature (OutletL.T); |
---|
36 | * the flash initial level (Level); |
---|
37 | * (NoComps - 1) OutletL (OR OutletV) compositions. |
---|
38 | "; |
---|
39 | |
---|
40 | PARAMETERS |
---|
41 | outer PP as Plugin (Brief = "External Physical Properties", Type="PP"); |
---|
42 | outer NComp as Integer (Brief = "Number of chemical components", Lower = 1); |
---|
43 | V as volume (Brief="Total Volume of the flash"); |
---|
44 | Mw(NComp) as molweight; |
---|
45 | orientation as Switcher (Valid=["vertical","horizontal"],Default="vertical"); |
---|
46 | diameter as length (Brief="Vessel diameter"); |
---|
47 | |
---|
48 | SET |
---|
49 | Mw=PP.MolecularWeight(); |
---|
50 | |
---|
51 | VARIABLES |
---|
52 | in Inlet as stream(Brief="Feed Stream", PosX=0, PosY=0.5421, Symbol="_{in}"); |
---|
53 | out OutletL as liquid_stream(Brief="Liquid outlet stream", PosX=0.4790, PosY=1, Symbol="_{outL}"); |
---|
54 | out OutletV as vapour_stream(Brief="Vapour outlet stream", PosX=0.4877, PosY=0, Symbol="_{outV}"); |
---|
55 | in InletQ as energy_stream (Brief="Rate of heat supply", PosX=1, PosY=0.7559, Symbol="_{in}"); |
---|
56 | |
---|
57 | M(NComp) as mol (Brief="Molar Holdup in the tray"); |
---|
58 | ML as mol (Brief="Molar liquid holdup"); |
---|
59 | MV as mol (Brief="Molar vapour holdup"); |
---|
60 | E as energy (Brief="Total Energy Holdup on tray"); |
---|
61 | vL as volume_mol (Brief="Liquid Molar Volume"); |
---|
62 | vV as volume_mol (Brief="Vapour Molar volume"); |
---|
63 | Level as length (Brief="liquid height"); |
---|
64 | Across as area (Brief="Flash Cross section area"); |
---|
65 | vfrac as positive (Brief="Vapourization fraction", Symbol="\phi"); |
---|
66 | Pratio as positive (Brief = "Pressure Ratio", Symbol ="P_{ratio}"); |
---|
67 | Pdrop as press_delta (Brief = "Pressure Drop", DisplayUnit = 'kPa', Symbol ="\Delta P"); |
---|
68 | |
---|
69 | EQUATIONS |
---|
70 | "Component Molar Balance" |
---|
71 | diff(M)=Inlet.F*Inlet.z - OutletL.F*OutletL.z - OutletV.F*OutletV.z; |
---|
72 | |
---|
73 | "Energy Balance" |
---|
74 | diff(E) = Inlet.F*Inlet.h - OutletL.F*OutletL.h - OutletV.F*OutletV.h + InletQ.Q; |
---|
75 | |
---|
76 | "Molar Holdup" |
---|
77 | M = ML*OutletL.z + MV*OutletV.z; |
---|
78 | |
---|
79 | "Energy Holdup" |
---|
80 | E = ML*OutletL.h + MV*OutletV.h - OutletL.P*V; |
---|
81 | |
---|
82 | "Mol fraction normalisation" |
---|
83 | sum(OutletL.z)=1.0; |
---|
84 | |
---|
85 | "Mol fraction normalisation" |
---|
86 | sum(OutletL.z)=sum(OutletV.z); |
---|
87 | |
---|
88 | "Vaporization Fraction" |
---|
89 | OutletV.F = Inlet.F * vfrac; |
---|
90 | |
---|
91 | "Liquid Volume" |
---|
92 | vL = PP.LiquidVolume(OutletL.T, OutletL.P, OutletL.z); |
---|
93 | |
---|
94 | "Vapour Volume" |
---|
95 | vV = PP.VapourVolume(OutletV.T, OutletV.P, OutletV.z); |
---|
96 | |
---|
97 | "Chemical Equilibrium" |
---|
98 | PP.LiquidFugacityCoefficient(OutletL.T, OutletL.P, OutletL.z)*OutletL.z = |
---|
99 | PP.VapourFugacityCoefficient(OutletV.T, OutletV.P, OutletV.z)*OutletV.z; |
---|
100 | |
---|
101 | "Thermal Equilibrium" |
---|
102 | OutletV.T = OutletL.T; |
---|
103 | |
---|
104 | "Mechanical Equilibrium" |
---|
105 | OutletV.P = OutletL.P; |
---|
106 | |
---|
107 | "Pressure Drop" |
---|
108 | OutletL.P = Inlet.P - Pdrop; |
---|
109 | |
---|
110 | "Pressure Ratio" |
---|
111 | OutletL.P = Inlet.P * Pratio; |
---|
112 | |
---|
113 | "Geometry Constraint" |
---|
114 | V = ML * vL + MV * vV; |
---|
115 | |
---|
116 | switch orientation |
---|
117 | case "vertical": |
---|
118 | "Cross Section Area" |
---|
119 | Across = 0.5 * asin(1) * diameter^2; |
---|
120 | |
---|
121 | "Liquid Level" |
---|
122 | ML * vL = Across * Level; |
---|
123 | |
---|
124 | case "horizontal": |
---|
125 | "Cylindrical Side Area" |
---|
126 | Across = 0.25*diameter^2 * (asin(1) - asin((diameter - 2*Level)/diameter)) + |
---|
127 | (Level - 0.5*diameter)*sqrt(Level*(diameter - Level)); |
---|
128 | |
---|
129 | "Liquid Level" |
---|
130 | 0.5 * asin(1) * diameter^2 * ML* vL = Across * V; |
---|
131 | end |
---|
132 | end |
---|
133 | |
---|
134 | #*---------------------------------------------------------------------- |
---|
135 | * Model of a Steady State flash |
---|
136 | *---------------------------------------------------------------------*# |
---|
137 | Model flash_steady |
---|
138 | ATTRIBUTES |
---|
139 | Pallete = true; |
---|
140 | Icon = "icon/Flash"; |
---|
141 | Brief = "Model of a Steady State flash."; |
---|
142 | Info = |
---|
143 | "== Assumptions == |
---|
144 | * both phases are perfectly mixed. |
---|
145 | |
---|
146 | == Specify == |
---|
147 | * the feed stream; |
---|
148 | * the outlet pressure (OutletV.P); |
---|
149 | * the outlet temperature OR the heat supplied. |
---|
150 | "; |
---|
151 | |
---|
152 | PARAMETERS |
---|
153 | outer PP as Plugin(Brief = "External Physical Properties", Type="PP"); |
---|
154 | |
---|
155 | VARIABLES |
---|
156 | in Inlet as stream(Brief="Feed Stream", PosX=0, PosY=0.5421, Symbol="_{in}"); |
---|
157 | out OutletL as liquid_stream(Brief="Liquid outlet stream", PosX=0.4790, PosY=1, Symbol="_{outL}"); |
---|
158 | out OutletV as vapour_stream(Brief="Vapour outlet stream", PosX=0.4877, PosY=0, Symbol="_{outV}"); |
---|
159 | in InletQ as energy_stream (Brief="Rate of heat supply", PosX=1, PosY=0.7559, Symbol="_{in}"); |
---|
160 | vfrac as fraction (Brief="Vapourization fraction", Symbol="\phi"); |
---|
161 | Pratio as positive (Brief = "Pressure Ratio", Symbol ="P_{ratio}"); |
---|
162 | Pdrop as press_delta (Brief = "Pressure Drop", DisplayUnit = 'kPa', Symbol ="\Delta P"); |
---|
163 | |
---|
164 | EQUATIONS |
---|
165 | "The flash calculation" |
---|
166 | [vfrac, OutletL.z, OutletV.z] = PP.Flash(OutletV.T, OutletV.P, Inlet.z); |
---|
167 | |
---|
168 | "Global Molar Balance" |
---|
169 | Inlet.F = OutletV.F + OutletL.F; |
---|
170 | |
---|
171 | "Vaporization Fraction" |
---|
172 | OutletV.F = Inlet.F * vfrac; |
---|
173 | |
---|
174 | "Energy Balance" |
---|
175 | Inlet.F*Inlet.h + InletQ.Q = OutletL.F*OutletL.h + OutletV.F*OutletV.h; |
---|
176 | |
---|
177 | "Thermal Equilibrium" |
---|
178 | OutletV.T = OutletL.T; |
---|
179 | |
---|
180 | "Mechanical Equilibrium" |
---|
181 | OutletV.P = OutletL.P; |
---|
182 | |
---|
183 | "Pressure Drop" |
---|
184 | OutletL.P = Inlet.P - Pdrop; |
---|
185 | |
---|
186 | "Pressure Ratio" |
---|
187 | OutletL.P = Inlet.P * Pratio; |
---|
188 | end |
---|
189 | |
---|
190 | #*---------------------------------------------------------------------- |
---|
191 | * Model of a steady-state PH flash. |
---|
192 | *---------------------------------------------------------------------*# |
---|
193 | Model FlashPHSteady |
---|
194 | ATTRIBUTES |
---|
195 | Pallete = true; |
---|
196 | Icon = "icon/Flash"; |
---|
197 | Brief = "Model of a static PH flash."; |
---|
198 | Info = |
---|
199 | "This model is for using the flashPH routine available on VRTherm. |
---|
200 | |
---|
201 | == Assumptions == |
---|
202 | * perfect mixing of both phases; |
---|
203 | |
---|
204 | == Specify == |
---|
205 | * the feed stream; |
---|
206 | * the heat duty; |
---|
207 | * the outlet pressure. |
---|
208 | "; |
---|
209 | |
---|
210 | PARAMETERS |
---|
211 | outer PP as Plugin(Brief = "External Physical Properties", Type="PP"); |
---|
212 | outer NComp as Integer; |
---|
213 | |
---|
214 | VARIABLES |
---|
215 | in Inlet as stream(Brief="Feed Stream", PosX=0, PosY=0.5421, Symbol="_{in}"); |
---|
216 | out OutletL as liquid_stream(Brief="Liquid outlet stream", PosX=0.4790, PosY=1, Symbol="_{outL}"); |
---|
217 | out OutletV as vapour_stream(Brief="Vapour outlet stream", PosX=0.4877, PosY=0, Symbol="_{outV}"); |
---|
218 | in InletQ as energy_stream (Brief="Rate of heat supply", PosX=1, PosY=0.7559, Symbol="_{in}"); |
---|
219 | vfrac as fraction(Brief="Vaporization fraction", Symbol="\phi"); |
---|
220 | h as enth_mol(Brief="Mixture enthalpy"); |
---|
221 | Pratio as positive (Brief = "Pressure Ratio", Symbol ="P_{ratio}"); |
---|
222 | Pdrop as press_delta (Brief = "Pressure Drop", DisplayUnit = 'kPa', Symbol ="\Delta P"); |
---|
223 | |
---|
224 | EQUATIONS |
---|
225 | |
---|
226 | "Chemical equilibrium" |
---|
227 | [vfrac,OutletL.z,OutletV.z]=PP.FlashPH(OutletL.P,h,Inlet.z); |
---|
228 | |
---|
229 | "Global Molar Balance" |
---|
230 | Inlet.F = OutletV.F + OutletL.F; |
---|
231 | OutletV.F = Inlet.F * vfrac; |
---|
232 | |
---|
233 | "Energy Balance" |
---|
234 | Inlet.F*(h - Inlet.h) = InletQ.Q; |
---|
235 | Inlet.F*h = Inlet.F*(1-vfrac)*OutletL.h + Inlet.F*vfrac*OutletV.h; |
---|
236 | |
---|
237 | "Thermal Equilibrium" |
---|
238 | OutletV.T = OutletL.T; |
---|
239 | |
---|
240 | "Mechanical Equilibrium" |
---|
241 | OutletV.P = OutletL.P; |
---|
242 | |
---|
243 | "Pressure Drop" |
---|
244 | OutletL.P = Inlet.P - Pdrop; |
---|
245 | |
---|
246 | "Pressure Ratio" |
---|
247 | OutletL.P = Inlet.P * Pratio; |
---|
248 | end |
---|
249 | |
---|
250 | #*---------------------------------------------------------------------- |
---|
251 | * Another model of a steady-state PH flash. |
---|
252 | * It is recommended to use [v,x,y]=PP.FlashPH(P,h,z) instead of. |
---|
253 | *---------------------------------------------------------------------*# |
---|
254 | Model FlashPHSteadyA |
---|
255 | ATTRIBUTES |
---|
256 | Pallete = true; |
---|
257 | Icon = "icon/Flash"; |
---|
258 | Brief = "Another model of a static PH flash."; |
---|
259 | Info = |
---|
260 | "This model shows how to model a pressure enthalpy flash |
---|
261 | directly with the EMSO modeling language. |
---|
262 | |
---|
263 | This model is for demonstration purposes only, the flashPH |
---|
264 | routine available on VRTherm is much more robust. |
---|
265 | |
---|
266 | == Assumptions == |
---|
267 | * perfect mixing of both phases; |
---|
268 | |
---|
269 | == Specify == |
---|
270 | * the feed stream; |
---|
271 | * the heat duty; |
---|
272 | * the outlet pressure. |
---|
273 | "; |
---|
274 | |
---|
275 | PARAMETERS |
---|
276 | outer PP as Plugin(Brief = "External Physical Properties", Type="PP"); |
---|
277 | outer NComp as Integer; |
---|
278 | B as Real(Default=1000, Brief="Regularization Factor"); |
---|
279 | |
---|
280 | VARIABLES |
---|
281 | in Inlet as stream(Brief="Feed Stream", PosX=0, PosY=0.5421, Symbol="_{in}"); |
---|
282 | out OutletL as liquid_stream(Brief="Liquid outlet stream", PosX=0.4790, PosY=1, Symbol="_{outL}"); |
---|
283 | out OutletV as vapour_stream(Brief="Vapour outlet stream", PosX=0.4877, PosY=0, Symbol="_{outV}"); |
---|
284 | in InletQ as energy_stream (Brief="Rate of heat supply", PosX=1, PosY=0.7559, Symbol="_{in}"); |
---|
285 | vfrac as fraction(Brief="Vaporization fraction", Symbol="\phi"); |
---|
286 | vsat as Real(Lower=-0.1, Upper=1.1, Brief="Vaporization fraction if saturated", Symbol="\phi_{sat}"); |
---|
287 | Tsat as temperature(Lower=173, Upper=1473, Brief="Temperature if saturated"); |
---|
288 | xsat(NComp) as Real(Lower=0, Upper=1, Brief="Liquid composition if saturated"); |
---|
289 | ysat(NComp) as Real(Lower=0, Upper=1, Brief="Vapour composition if saturated"); |
---|
290 | Pratio as positive (Brief = "Pressure Ratio", Symbol ="P_{ratio}"); |
---|
291 | Pdrop as press_delta (Brief = "Pressure Drop", DisplayUnit = 'kPa', Symbol ="\Delta P"); |
---|
292 | |
---|
293 | zero_one as fraction(Brief="Regularization Variable"); |
---|
294 | one_zero as fraction(Brief="Regularization Variable"); |
---|
295 | |
---|
296 | EQUATIONS |
---|
297 | "Chemical equilibrium" |
---|
298 | PP.LiquidFugacityCoefficient(Tsat, OutletL.P, xsat)*xsat = |
---|
299 | PP.VapourFugacityCoefficient(Tsat, OutletV.P, ysat)*ysat; |
---|
300 | |
---|
301 | "Global Molar Balance" |
---|
302 | Inlet.F = OutletV.F + OutletL.F; |
---|
303 | OutletV.F = Inlet.F * vfrac; |
---|
304 | |
---|
305 | "Component Molar Balance" |
---|
306 | Inlet.F*Inlet.z = OutletL.F*xsat + OutletV.F*ysat; |
---|
307 | sum(xsat) = sum(ysat); |
---|
308 | |
---|
309 | "Energy Balance if saturated" |
---|
310 | Inlet.F*Inlet.h + InletQ.Q = |
---|
311 | Inlet.F*(1-vsat)*PP.LiquidEnthalpy(Tsat, OutletL.P, xsat) + |
---|
312 | Inlet.F*vsat*PP.VapourEnthalpy(Tsat, OutletV.P, ysat); |
---|
313 | |
---|
314 | "Real Energy Balance" |
---|
315 | Inlet.F*Inlet.h + InletQ.Q = |
---|
316 | Inlet.F*(1-vfrac)*OutletL.h + Inlet.F*vfrac*OutletV.h; |
---|
317 | |
---|
318 | "Thermal Equilibrium" |
---|
319 | OutletV.T = OutletL.T; |
---|
320 | |
---|
321 | "Mechanical Equilibrium" |
---|
322 | OutletV.P = OutletL.P; |
---|
323 | |
---|
324 | "Pressure Drop" |
---|
325 | OutletL.P = Inlet.P - Pdrop; |
---|
326 | |
---|
327 | "Pressure Ratio" |
---|
328 | OutletL.P = Inlet.P * Pratio; |
---|
329 | |
---|
330 | # regularization functions |
---|
331 | zero_one = (1 + tanh(B * vsat))/2; |
---|
332 | one_zero = (1 - tanh(B * (vsat - 1)))/2; |
---|
333 | |
---|
334 | vfrac = zero_one * one_zero * vsat + 1 - one_zero; |
---|
335 | OutletL.z = zero_one*one_zero*xsat + (1-zero_one*one_zero)*Inlet.z; |
---|
336 | OutletV.z = zero_one*one_zero*ysat + (1-zero_one*one_zero)*Inlet.z; |
---|
337 | end |
---|