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valve.mso @ 808

Last change on this file since 808 was 808, checked in by gerson bicca, 14 years ago
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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	*---------------------------------------------------------------------
16	* Author: Estefane Horn, Núbia do Carmo Ferreira
17	*$Id: valve.mso 808 2009-08-03 21:15:55Z bicca $
18	-------------------------------------------------------------------#
19
20	using "streams";
21
22	#*-------------------------------------------------------------------
23	* Model of a valve (simplified)
24	*--------------------------------------------------------------------
25	*
26	* Author: Paula B. Staudt
27	--------------------------------------------------------------------#
28	Model valve_simplified
29	ATTRIBUTES
30	Pallete = true;
31	Icon = "icon/Valve";
32	Brief = "Model of a very simple valve - used in distillation column models.";
33	Info =
34	"== Assumptions ==
35	* no flashing liquid in the valve;
36	* the flow in the valve is adiabatic;
37	* dynamics in the valve are neglected;
38	* linear flow type.
39
40	== Specify ==
41	* the inlet stream
42	* the plug position (x) OR outlet temperature (Outlet.T) OR outlet pressure (Outlet.P)
43
44	OR
45
46	* the inlet stream excluding its flow (Inlet.F)
47	* the outlet pressure (Outlet.P) OR outlet flow (Outlet.F)
48	* the plug position (x)
49	";
50
51	PARAMETERS
52	outer PP as Plugin(Type="PP");
53	outer NComp as Integer;
54
55	VARIABLES
56	in Inlet as stream (Brief = "Inlet stream", PosX=0, PosY=0.7365, Symbol="_{in}");
57	out Outlet as streamPH (Brief = "Outlet stream", PosX=1, PosY=0.7365, Symbol="_{out}");
58	x as fraction (Brief="Plug Position");
59	rho as dens_mass (Brief="Fluid Density", Default=1e3);
60	v as vol_mol (Brief="Specific volume", Default=1e3);
61	Pdrop as press_delta (Brief = "Pressure Drop", DisplayUnit = 'kPa', Symbol ="\Delta P");
62	Pratio as positive (Brief = "Pressure Ratio", Symbol ="P_{ratio}");
63
64	PARAMETERS
65	rho_ref as dens_mass (Brief="Reference Density", Default=1e4);
66	k as Real (Brief="Valve Constant", Unit='gal/min/psi^0.5');
67
68	EQUATIONS
69	"Overall Molar Balance"
70	Inlet.F = Outlet.F;
71
72	"Componente Molar Balance"
73	Inlet.z = Outlet.z;
74
75	"Energy Balance"
76	Inlet.h = Outlet.h;
77
78	"Pressure Drop"
79	Outlet.P = Inlet.P - Pdrop;
80
81	"Pressure Ratio"
82	Outlet.P = Inlet.P * Pratio;
83
84	"Density"
85	rho = Inlet.v*PP.VapourDensity((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z) +
86	(1-Inlet.v)*PP.LiquidDensity((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z);
87
88	"Volume"
89	v = Inlet.v*PP.VapourVolume((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z) +
90	(1-Inlet.v)*PP.LiquidVolume((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z);
91
92	if Pdrop > 0 then
93	"Flow"
94	Outlet.F * v = kxsqrt(Pdrop * rho_ref / rho ) ;
95	else
96	"Closed"
97	Outlet.F = 0 * 'kmol/h';
98	end
99	end
100
101	Model valve_flow
102
103	ATTRIBUTES
104	Pallete = true;
105	Icon = "icon/Valve";
106	Brief = "Model of a very simple valve for setting the flow with a controller.";
107	Info =
108	"== ASSUMPTIONS ==
109	* nothing happens in this valve
110
111	== SET ==
112	* MinFlow: the Minimum Flow Allowable in the valve;
113	* MaxFlow: the Maximum Flow Allowable in the valve;
114
115	== SPECIFY ==
116	* the Inlet stream
117	* the FlowFraction (the model requires an inlet signal, also you can use a controller for setting the FlowFraction)
118	";
119
120	PARAMETERS
121	outer PP as Plugin (Brief = "External Physical Properties", Type="PP");
122	outer NComp as Integer (Brief="Number of Components");
123
124	MinFlow as flow_mol(Brief="Minimum Flow Allowable in the valve", Default=0);
125	MaxFlow as flow_mol(Brief="Maximum Flow Allowable in the valve", Default=1000);
126
127	VARIABLES
128
129	in Inlet as stream (Brief ="Inlet stream", PosX=0, PosY=0.7365, Symbol="_{in}",Protected=true);
130	out Outlet as stream (Brief ="Outlet stream", PosX=1, PosY=0.7365, Symbol="_{out}",Protected=true);
131	in FlowFraction as fraction (Brief ="Flow Signal", PosX=0.5, PosY=0,Protected=true);
132
133	EQUATIONS
134	"Overall Molar Balance"
135	Outlet.F = Inlet.F;
136
137	"Temperature"
138	Outlet.T = Inlet.T;
139
140	"Pressure"
141	Outlet.P = Inlet.P;
142
143	"Energy Balance"
144	Outlet.h = Inlet.h;
145
146	"Vapour fraction"
147	Outlet.v = Inlet.v;
148
149	"Componente Molar Balance"
150	Outlet.z = Inlet.z;
151
152	"Flow computation"
153	Outlet.F = MinFlow + FlowFraction*(MaxFlow-MinFlow);
154
155	end
156
157	Model valve
158
159	ATTRIBUTES
160	Pallete = true;
161	Icon = "icon/Valve";
162	Brief = "Model of a valve.";
163	Info =
164	"== Model of valves ==
165	* Linear;
166	* Parabolic;
167	* Equal;
168	* Quick;
169	* Hyperbolic.
170
171	== Assumptions ==
172	* First Order Dynamic;
173	* Only Liquid or Only Vapour;
174	* Isentalpic.
175
176	== Specify ==
177	* the valve type;
178	* the Valve Coefficient (Cv);
179	* the valve time constant (Tau).
180	";
181
182	PARAMETERS
183
184	outer PP as Plugin (Brief = "External Physical Properties", Type = "PP");
185	outer NComp as Integer (Brief = "Number of chemical components", Lower = 1);
186
187	ValveType as Switcher (Valid = ["linear", "parabolic", "equal", "quick", "hyperbolic"], Default = "linear");
188	ValidPhases as Switcher (Brief = "Valid Phases for Flash Calculation", Valid = ["Vapour-Only", "Liquid-Only"], Default="Liquid-Only");
189	# Tau as time_sec (Brief="valve time constant");
190	rho60F as dens_mass (Brief = "Water Mass Density at 60 F",Hidden=true);
191
192	VARIABLES
193	W as flow_mass(DisplayUnit='kg/s');
194	Pdrop as press_delta (Brief = "Pressure Drop", DisplayUnit = 'kPa', Symbol ="\Delta P");
195	Fvol as flow_vol (Brief = "Volumetric Flow");
196	fc as positive (Brief = "Opening Function",Hidden=true);
197	Cv as Real (Brief="Valve Flow Coefficient", Unit='gal/min/psi^0.5');
198	Cv1 as Real (Brief="Valve Flow Coefficient", Unit='m^2');
199	Cg as Real (Brief="Valve Gas Flow Coefficient", Unit='ft^3/h/psi');
200	C as Real (Brief="Liquid-gas Coefficient Ratio", Unit='(ft^3/gal)*(min/h)/(psi^.5)');
201	StemPosition as fraction (Brief = "Actual valve stem position");
202	a as Real;
203	#b as Real (Brief="d", Unit='1/(psi^.5)');
204	vm as vol_mol (Brief = "Mixture Molar Volume");
205	rho as dens_mass (Brief = "Mixture Mass Density");
206	# vsp as fraction (Brief = "Valve stem position",Hidden=true);
207
208	in Inlet as stream (Brief = "Inlet stream", PosX=0, PosY=0.7365, Symbol="_{in}");
209	out Outlet as streamPH (Brief = "Outlet stream", PosX=1, PosY=0.7365, Symbol="_{out}");
210	#in vsignal as fraction (Brief = "Flow Signal", PosX=0.5, PosY=0);
211
212	SET
213
214	rho60F = 984.252 * 'kg/m^3';
215
216	EQUATIONS
217
218	#"First order valve dynamics"
219	# Tau*diff(StemPosition) = vsp-StemPosition;
220
221	#"Flow Signal"
222	# vsp = vsignal;
223
224	"Pressure Drop"
225	Outlet.P = Inlet.P - Pdrop;
226
227	"Enthalpy Balance"
228	Outlet.h = Inlet.h;
229
230	"Molar Balance"
231	Outlet.F = Inlet.F;
232
233	"Outlet Composition"
234	Outlet.z = Inlet.z;
235
236	Cv1=Cv'1/(gal/min/psi^0.5)'2.3837e-5*'m^2';
237
238	switch ValidPhases
239
240	#############################################################
241
242	case "Liquid-Only":
243
244	if Pdrop > 0 then
245
246	"Valve Equation - Liquid Flow"
247	Fvol = fc(Cv/sqrt(1/rho60F))sqrt(Pdrop/rho);
248	"Liquid-gas Coefficient Ratio"
249	C*Cv=Cg;
250	a=1/(1.6764e-2C'1/((ft^3/gal)(min/h)/(psi^.5))')sqrt(Pdrop/Inlet.P);
251	else
252
253	"Valve Equation - Liquid Flow"
254	Fvol = fc(Cv/sqrt(1/rho60F))sqrt(Pdrop/rho);
255	"Liquid-gas Coefficient Ratio"
256	C*Cv=Cg;
257	a=1/(1.6764e-2C'1/((ft^3/gal)(min/h)/(psi^.5))')sqrt(Pdrop/Inlet.P);
258	end
259
260	"Liquid Mass Density"
261	rho = PP.LiquidDensity(Inlet.T,Inlet.P,Inlet.z);
262
263	"Liquid Molar Volume"
264	vm = PP.LiquidVolume(Inlet.T,Inlet.P,Inlet.z);
265
266
267
268	############################################################
269
270	case "Vapour-Only":
271
272	if Pdrop > 0 then #Update for gas flow !!!!
273
274	"Liquid-gas Coefficient Ratio"
275	C*Cv=Cg;
276	a=1/(1.6764e-2C'1/((ft^3/gal)(min/h)/(psi^.5))')sqrt(Pdrop/Inlet.P);
277
278	if 1.5708 > a then
279	"Valve Equation - Vapour Flow"
280	#Fvol = fcCgsqrt(Inlet.P/1000*rho60F/rho);####rho60f/rho ok!!!!
281	#Fvol = fcCvsqrt(Pdrop/1000*rho60F/rho);
282	#W = fcCv1sqrt(Pdrop/1000*rho);
283	Fvol = fc0.13446'psi^.5'Cgsqrt(Inlet.P/1000rho60F/rho)sin(a*'rad');
284
285	else
286	"Valve Equation - Vapour Flow"
287	Fvol = fc0.13446Cvsqrt(Inlet.Prho60F/rho);
288	end
289	else
290
291	"Valve Equation - Vapour Flow"
292	Fvol = fc(Cv/sqrt(1/rho60F))sqrt(Pdrop/rho);
293
294	"Liquid-gas Coefficient Ratio"
295	C*Cv=Cg;
296	a=1/(1.6764e-2C'1/((ft^3/gal)(min/h)/(psi^.5))')sqrt(Pdrop/Inlet.P);
297	end
298
299	"Vapour Mass Density"
300	rho = PP.VapourDensity(Inlet.T,Inlet.P,Inlet.z);
301	#rho=3.708741*'kg/m^3';
302	"Vapour Molar Volume"
303	vm = PP.VapourVolume(Inlet.T,Inlet.P,Inlet.z);
304
305	end
306
307	######################################################
308
309	"Calculate Mass Flow"
310	Fvol = Inlet.F*vm;
311
312	W=Fvol*rho;
313
314
315	switch ValveType #Update the valve Type
316
317	case "linear":
318
319	"Opening Equation"
320	fc = StemPosition;
321
322	case "parabolic":
323
324	"Opening Equation"
325	fc = StemPosition^2;
326
327	case "equal":
328
329	"Opening Equation"
330	fc = StemPosition^2/(2-StemPosition^4)^(1/2);
331
332	case "quick":
333
334	"Opening Equation"
335	fc = 10StemPosition/sqrt(1+99StemPosition^2);
336
337	case "hyperbolic":
338
339	"Opening Equation"
340	fc = 0.1StemPosition/sqrt(1-0.99StemPosition^2);
341
342	end
343
344	end
345

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