dip_10.ppt p. 1 diseño integrado de procesos (simulador) dip 10.ppt separation of a mixture of...
Post on 27-Mar-2015
215 Views
Preview:
TRANSCRIPT
DIP_10.ppt p. 1
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
DIP 10.ppt
Separation of a mixture of methanol + water
• Property Method Selection • Model parameters• Experimental data correlation• Optimization • Columns specifications
DIP_10.ppt p. 2
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
The problem...
Separate a 100 kmol/h stream mixture of methanol + water in an atmospheric column.
• Property Method: a collection of methods and models to evaluate physical properties and phase equilibrium.
• The first step is choosing the appropriate property method.
DIP_10.ppt p. 3
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
Property Method Selection
DIP_10.ppt p. 4
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
• Main characteristic: phase equilibria calculation. Classification:
• IDEAL• EOS (PR, RK, BWR,....)• Activity coefficient (NRTL, UNIFAC, ...)• Electrolites (ELECNRTL, PITZER)• Special methods (AMINES, STEAMNBS,...)
• Selection: Help
DIP_10.ppt p. 5
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
DIP_10.ppt p. 6
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
1
DIP_10.ppt p. 7
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
2
DIP_10.ppt p. 8
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
3
DIP_10.ppt p. 9
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
More about Property Methods ... APrSystem Help: /Data /Properties [F1]
DIP_10.ppt p. 10
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
Separation of a mixture of methanol + water in an atmospheric column:
Open a new file (General with metric units) and define components (METHANOL, WATER) and Property Method (NRTL).
Polar ?
Electrolyte ?
Yes
P < 10 bar ?
No
ij ?
Yes
LL ?
Yes
Wilson, NRTL, UNIQAC
No
DIP_10.ppt p. 11
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
How does the Property Method calculate a specific property?
The properties used in the simulation are classified into categories depending on how they are evaluated:
Some general concepts:
1. MODELS
2. METHODS
3. ROUTES
DIP_10.ppt p. 12
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
How does the Property Method calculate a specific property?
The properties used in the simulation are classified into categories depending on how they are evaluated:
1. MODELS: models calculate properties by direct use of an empirical expression or a theoretical model. For example:
GAMMA: liquid mixture activity coefficients.Possible MODELS: GMRENON: NRTL original
GMUFAC: UNIFAC
GMUFDMD: UNIFAC, modif. Dormund
.... (up to 32 MODELS)
DIP_10.ppt p. 13
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
2. METHODS: in this case the property is evaluated using a thermodynamic expression where required properties are evaluated with MODELS. Different thermodynamic expressions (METHODS) may be available to evaluate a specific property.
For example, four METHODS are available to evaluate the enthalpy of a liquid mixture (HLMX) :
METHOD 1: Empiric expressionHLMX = f(T, P, x_i,
parámetros)
METHOD 2: From the ideal liquid mixture enthalpy (Hi*L) y the excess
enthalpy (HEX).HLMX = Σxi Hi
*L + HEX
METHOD 3: From ideal gas mixture enthalpy (Hmig) and departure
enthalpy (Hdepart):HLMX = Hm
ig + Hdepart
METHOD 4: ElectrolytesHLMX = f(xTRUE)
How does the Property Method calculate a specific property?
The properties used in the simulation are classified into categories depending on how they are evaluated:
DIP_10.ppt p. 14
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
3. ROUTES: The group of specific METHOD and MODELS selected to evaluate a property is named a ROUTE.
How does the Property Method calculate a specific property?
The properties used in the simulation are classified into categories depending on how they are evaluated:
DIP_10.ppt p. 15
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
• /Properties / Property Methods /NRTL: Routes , Select HLMX, View
View a ROUTE description
DIP_10.ppt p. 16
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
DIP_10.ppt p. 17
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
Types of properties depending on their use and how they are calculated:
MAJOR: Are those properties required for calculations by unit operation models. They ere evaluated according to ROUTES, and may depend on other MAJOR, SUBORDINATE and INTERMEDIATE properties .
Properties: PHI, H, G, S, V, MU, K, D, SIGMA (Pure and mixtures)
SUBORDINATE: these properties are also calculated using ROUTES, but are not directly required for unit operation model calculations. They are used to calculate MAJOR properties.
Ex.: HLXS (excess enthalpy), ...
INTERMEDIATE: calculated by MODELS, they are used to calculate MAJOR and SUBORDINATE properties.
Ex.: GAMMA (activity coefficients),...
How does the Property Method calculate a specific property?
DIP_10.ppt p. 18
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
• /Properties / Property Methods /NRTL: Models , Select GMRENON
Check a MODEL
F1
DIP_10.ppt p. 19
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
Model ParametersReid,Prausnitz y Pooling, The Properties of Gases & Liquids, 4th Ed, Cap. 8, p. 380-1.
DIP_10.ppt p. 20
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
The recommended order of use of the parameters (the same one used by Aspen): 1) experimental values (parameters or data correlation) 2) bibliographic (literature or Aspen database) 3) Estimates (PCES)
Points 2 and 3 have already been presented in previous classes.
• Check parameters: /Properties /Parameters /Binary interaction /NRTL-1• Check residuals from correlation (press button [Reg. Info] after selecting the parameter)• Check parameters available from other Databanks.
DIP_10.ppt p. 21
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
• Add a second model (/Properties /Specifications: Referenced -> WILSON) and compare residuals with NRTL model (F1).
DIP_10.ppt p. 22
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
Experimental data correlation
Correlate equilibrium TXY values at 760 mmHg: Ramalho R.S. et al, Ind.Eng.Chem. 53, 89 (1961)
• Change Run Type in Setup form to Data Regression.• /Properties /Data: New
• ID: D-1• Select type: MIXTURE• Write literature citation in the comments form• Write data
T (ºC) xMEOH yMEOH95.2 0.0293 0.183189.2 0.0948 0.414277.6 0.3004 0.688274.0 0.4564 0.766865.7 0.9293 0.9771
DIP_10.ppt p. 23
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
• /Properties /Regression: New
DIP_10.ppt p. 24
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
Help on NRTL parameters (F1)
DIP_10.ppt p. 25
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
• Modify the selection of parameters to be regressed: aij = 0bij regresscij = 0.30
Metanol+Agua_01.apw
DIP_10.ppt p. 26
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
• Run: confirm parameters replacement when asked.
Metanol+Agua_02.apw
DIP_10.ppt p. 27
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
NRTL parameters have been replaced in /Properties /Parameters /Binary Interaction /NRTL-1
DIP_10.ppt p. 28
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
Plot using Plot Wizard from form: /Regression /R-1 /Results: Profiles
DIP_10.ppt p. 29
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
Check other results in /Regression /R-1 /Results
DIP_10.ppt p. 30
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
Selection criteria:
• Choose the model giving the lowest Residual Root Mean Square.
Non-trustable regressions:
• A standard deviation for a regressed parameter is 0.0, indicating the parameter is at a bound.
• A large residual root mean square error value. Normally, this value should be less than 10 for VLE data and less than 100 for LLE data.
• Your VLE data fail the thermodynamic consistency test.
DIP_10.ppt p. 31
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
Optimization
• /Setup: Run Type -> Flowsheet.• Draw PFD, stream 1 and column.
It is intended to separate a 100 kmol/h stream containing a mixture of MeOH + water (60 mol% MeOH). The mixture is 1 bar and it is at its boiling point. Use first a shortcut (DSTWU) to design a tower with a recovery of 99% for further optimization.
Corriente 1
Metanol+Agua_03.apw
DIP_10.ppt p. 32
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
Results...
DIP_10.ppt p. 33
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
Operation will be optimized using an objective function to minimize total costs:
. . .. . B CN Q Q
F OLKR
2
0 012 8 3 4 6
, where N is the number of theoretical stages, QB the reboiler duty, QC the condenser duty and LKR is the light key recovery. Perform a sensitivity analysis to study the behavior of the tower prior to the optimization.
• /Model Analysis Tools /Sensitivity: New, S-1
DIP_10.ppt p. 34
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
Results:
Metanol+Agua_04.apw
DIP_10.ppt p. 35
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
• /Model Analysis Tools /Sensitivity: S-1, Hide• /Model Analysis Tools /Optimization: New, O-1
Optimization:
DIP_10.ppt p. 36
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
/Convergence/Convergence/$OLVER01/Results
Metanol+Agua_05.apw
DIP_10.ppt p. 37
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
NOTE: although the optimization block is hidden (Hide) or deleted (Delete) the value of the optimized variable is preserved, if not ‘Reinitialize' is performed. This is because the optimized value of the variable is retained in the results form.
/Blocks /D-110 /Input /Blocks /D-110 /Results
0.49601.093
0.4536mín
RR
RR
DIP_10.ppt p. 38
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
• /Model Analysis Tools /Optimization: O-1 -> Hide• Write calculated design and operating variables: 31 stages, feed stage=20, D/F=0.598,
RR=0.4960• Change to RADFRAC• /Setup /Report Options /Stream: Fraction Basis – Mole: ON
Replace the shortcut (DSTWU) for a rigorous (RADFRAC) unit operation.
Resultados
Metanol+Agua_06.apw
DIP_10.ppt p. 39
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
• /Blocks /D-110 /Design Specs: New = 1• Specify 99.2%mol MeOH in stream 2
Let's see now, forgetting the optimization, how purity may be specified in distillate and bottoms, allowing the software evaluate operating variables.
/Blocks /D-110 /Design Specs /1
DIP_10.ppt p. 40
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
• /Blocks /D-110 /Vary: New = 1• Allow RR vary between 0.1 y 10
/Blocks /D-110 /Vary /1
• Run
/Blocks /D-110 /Design Spec /1 /Blocks /D-1101 /Vary /1
Metanol+Agua_07.apw
DIP_10.ppt p. 41
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
• /Blocks /D-110 /Design Specs: New = 2• Specify 99%mol WATER in stream 3
Specify now 99%mol WATER in stream 3, varying another column specification
/Blocks /D-110 /Design Specs /2
/Blocks /D-110 /Vary /2
Metanol+Agua_08.apw
DIP_10.ppt p. 42
Dis
eño
Inte
gra
do
de
Pro
ceso
s (S
imu
lad
or)
/Blocks /D-110 /Vary /2
/Blocks /D-110 /Results /Blocks /D-110 /Stream Results
top related