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# The Institute for the Design of Advanced Energy Systems Integrated Platform
# Framework (IDAES IP) was produced under the DOE Institute for the
# Design of Advanced Energy Systems (IDAES).
#
# Copyright (c) 2018-2023 by the software owners: The Regents of the
# University of California, through Lawrence Berkeley National Laboratory,
# National Technology & Engineering Solutions of Sandia, LLC, Carnegie Mellon
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Supercritical CO2 Property Surrogate with ALAMO Surrogate Object - flowsheet_optimization (Part 3)#
Maintainer: Javal Vyas
Author: Javal Vyas
Updated: 2024-01-24
With the surrogate model being embedded in the property package, it is ready to be used in the flowsheet. We start by creating the following flowsheet using the IDAES package.
from IPython.display import Image
from pathlib import Path
def datafile_path(name):
return Path("..") / name
Image(datafile_path("CO2_flowsheet.png"))
1. Importing libraries#
We will be using the unit models from the IDAES
package along with components from pyomo.environ
and pyomo.network
.
from pyomo.environ import (ConcreteModel,
Block,
Var,
Param,
Constraint,
SolverFactory,
TransformationFactory, TerminationCondition,
value, Expression, minimize, units)
from pyomo.network import Arc, SequentialDecomposition
# Import IDAES libraries
from idaes.core import FlowsheetBlock, UnitModelBlockData
from idaes.models.unit_models import (Mixer, MomentumMixingType,
PressureChanger, Heater,
Separator, HeatExchanger)
from idaes.models.unit_models.pressure_changer import ThermodynamicAssumption
from idaes.core.util.model_statistics import degrees_of_freedom
from idaes.core.util.initialization import propagate_state
from properties import SCO2ParameterBlock
import idaes.logger as idaeslog
_log = idaeslog.getModelLogger("my_model", level=idaeslog.DEBUG, tag="model")
2. Constructing the flowsheet#
To construct the flowsheet we need to define a ConcreteModel using pyomo and then add a FlowsheetBlock to the ConcreteModel. Here since we are focusing on the steady state process, we shall have the dynamic flag as False in the FlowsheetBlock. Next, we define the properties in the FlowsheetBlock that we imported from the properties.py file. Then start adding the unit models to the FlowsheetBlock with the suitable arguments, after which we connect them using Arcs as in the flowsheet above.
Once we have the connected flowsheet, we initialize individual unit models. Before initializing, we fix desired variables for the desired behavior of the unit model and then use propagate_state
to pass on the state variables to next unit model in the flowsheet. After completely initializing the flowsheet, we convert the network to a mathematical form by using network.expand_arcs
from the TransformationFactory and apply it on the flowsheet block. Then we call the solver and solve the flowsheet to calculate the total work in the process.
def main():
# Setup solver and options
solver = SolverFactory('ipopt')
outlvl = 0
tee = True
# Set up concrete model
m = ConcreteModel()
# Create a flowsheet block
m.fs = FlowsheetBlock(dynamic=False)
# Create the properties param block
m.fs.properties = SCO2ParameterBlock()
# Add unit models to the flowsheet
m.fs.boiler = Heater(dynamic=False,property_package= m.fs.properties,has_pressure_change=True)
m.fs.turbine = PressureChanger(dynamic=False,
property_package= m.fs.properties,
compressor=False,
thermodynamic_assumption=ThermodynamicAssumption.isentropic)
m.fs.HTR_pseudo_shell = Heater(dynamic= False,
property_package= m.fs.properties,
has_pressure_change= True)
m.fs.HTR_pseudo_tube = Heater(dynamic=False,
property_package= m.fs.properties,
has_pressure_change= True)
m.fs.LTR_pseudo_shell = Heater(dynamic= False,
property_package= m.fs.properties,
has_pressure_change=True)
m.fs.LTR_pseudo_tube = Heater(dynamic= False,
property_package= m.fs.properties,
has_pressure_change=True)
m.fs.splitter_1 = Separator(property_package= m.fs.properties,
outlet_list= ["bypass", "to_cooler"])
m.fs.co2_cooler = Heater(dynamic= False,
property_package=m.fs.properties,
has_pressure_change= True)
m.fs.main_compressor = PressureChanger(dynamic= False,
property_package= m.fs.properties,
compressor= True,
thermodynamic_assumption= ThermodynamicAssumption.isentropic)
m.fs.bypass_compressor = PressureChanger(dynamic= False,
property_package= m.fs.properties,
compressor= True,
thermodynamic_assumption= ThermodynamicAssumption.isentropic)
m.fs.splitter_2 = Separator(property_package= m.fs.properties,
ideal_separation= False,
outlet_list= ["to_FG_cooler",
"to_LTR"])
m.fs.FG_cooler = Heater(dynamic= False,
property_package= m.fs.properties,
has_pressure_change= True)
m.fs.mixer = Mixer(property_package= m.fs.properties,
inlet_list=["FG_out", "LTR_out", "bypass"])
# # Connect the flowsheet
m.fs.s01 = Arc(source=m.fs.boiler.outlet,
destination=m.fs.turbine.inlet)
m.fs.s02 = Arc(source=m.fs.turbine.outlet,
destination=m.fs.HTR_pseudo_shell.inlet)
m.fs.s03 = Arc(source=m.fs.HTR_pseudo_shell.outlet,
destination=m.fs.LTR_pseudo_shell.inlet)
m.fs.s04 = Arc(source=m.fs.LTR_pseudo_shell.outlet,
destination=m.fs.splitter_1.inlet)
m.fs.s05 = Arc(source=m.fs.splitter_1.to_cooler,
destination=m.fs.co2_cooler.inlet)
m.fs.s06 = Arc(source=m.fs.splitter_1.bypass,
destination=m.fs.bypass_compressor.inlet)
m.fs.s07 = Arc(source=m.fs.co2_cooler.outlet,
destination=m.fs.main_compressor.inlet)
m.fs.s08 = Arc(source=m.fs.bypass_compressor.outlet,
destination=m.fs.mixer.bypass)
m.fs.s09 = Arc(source=m.fs.main_compressor.outlet,
destination=m.fs.splitter_2.inlet)
m.fs.s10 = Arc(source=m.fs.splitter_2.to_FG_cooler,
destination=m.fs.FG_cooler.inlet)
m.fs.s11 = Arc(source=m.fs.splitter_2.to_LTR,
destination=m.fs.LTR_pseudo_tube.inlet)
m.fs.s12 = Arc(source=m.fs.LTR_pseudo_tube.outlet,
destination=m.fs.mixer.LTR_out)
m.fs.s13 = Arc(source=m.fs.FG_cooler.outlet,
destination=m.fs.mixer.FG_out)
m.fs.s14 = Arc(source=m.fs.mixer.outlet,
destination=m.fs.HTR_pseudo_tube.inlet)
# NETL Baseline
m.fs.boiler.inlet.flow_mol.fix(121.1)
m.fs.boiler.inlet.temperature.fix(685.15)
m.fs.boiler.inlet.pressure.fix(34.51)
m.fs.boiler.outlet.temperature.fix(893.15) # Turbine inlet T = 620 C
m.fs.boiler.deltaP.fix(-0.21)
m.fs.boiler.initialize(outlvl=outlvl)
propagate_state(m.fs.s01)
m.fs.turbine.ratioP.fix(1/3.68)
m.fs.turbine.efficiency_isentropic.fix(0.927)
m.fs.turbine.initialize(outlvl=outlvl)
propagate_state(m.fs.s02)
m.fs.HTR_pseudo_shell.outlet.temperature.fix(489.15)
m.fs.HTR_pseudo_shell.deltaP.fix(-0.07)
m.fs.HTR_pseudo_shell.initialize(outlvl=outlvl)
propagate_state(m.fs.s03)
m.fs.LTR_pseudo_shell.outlet.temperature.fix(354.15)
m.fs.LTR_pseudo_shell.deltaP.fix(-0.07)
m.fs.LTR_pseudo_shell.initialize(outlvl=outlvl)
propagate_state(m.fs.s04)
m.fs.splitter_1.split_fraction[0, "bypass"].fix(0.25)
m.fs.splitter_1.initialize(outlvl=outlvl)
propagate_state(m.fs.s05)
m.fs.co2_cooler.outlet.temperature.fix(308.15)
m.fs.co2_cooler.deltaP.fix(-0.07)
m.fs.co2_cooler.initialize(outlvl=outlvl)
propagate_state(m.fs.s06)
m.fs.bypass_compressor.efficiency_isentropic.fix(0.85)
m.fs.bypass_compressor.ratioP.fix(3.8)
m.fs.bypass_compressor.initialize(outlvl=outlvl)
propagate_state(m.fs.s07)
m.fs.main_compressor.efficiency_isentropic.fix(0.85)
m.fs.main_compressor.ratioP.fix(3.8)
m.fs.main_compressor.initialize(outlvl=outlvl)
propagate_state(m.fs.s09)
m.fs.splitter_2.split_fraction[0, "to_FG_cooler"].fix(0.046)
m.fs.splitter_2.initialize(outlvl=outlvl)
propagate_state(m.fs.s10)
m.fs.FG_cooler.outlet.temperature.fix(483.15)
m.fs.FG_cooler.deltaP.fix(-0.06)
m.fs.FG_cooler.initialize(outlvl=outlvl)
propagate_state(m.fs.s11)
m.fs.LTR_pseudo_tube.deltaP.fix(0)
m.fs.LTR_pseudo_tube.heat_duty[0].\
fix(-value(m.fs.LTR_pseudo_shell.heat_duty[0]))
m.fs.LTR_pseudo_tube.initialize(outlvl=outlvl)
# Add constraint heats of the LTR_pseudo shell and tube
m.fs.LTR_pseudo_tube.heat_duty[0].unfix()
m.fs.c1 = Constraint(expr=m.fs.LTR_pseudo_shell.heat_duty[0] ==
-m.fs.LTR_pseudo_tube.heat_duty[0])
propagate_state(m.fs.s08)
propagate_state(m.fs.s12)
propagate_state(m.fs.s13)
m.fs.mixer.initialize(outlvl=outlvl)
propagate_state(m.fs.s14)
m.fs.HTR_pseudo_tube.heat_duty[0].\
fix(-value(m.fs.HTR_pseudo_shell.heat_duty[0]))
m.fs.HTR_pseudo_tube.deltaP.fix(-0.07)
m.fs.HTR_pseudo_tube.initialize(outlvl=outlvl)
m.fs.HTR_pseudo_tube.heat_duty[0].unfix()
m.fs.c2 = Constraint(expr=m.fs.HTR_pseudo_shell.heat_duty[0] ==
-m.fs.HTR_pseudo_tube.heat_duty[0])
TransformationFactory("network.expand_arcs").apply_to(m.fs)
print("--------------------------------------------------------------------")
print("The degrees of freedom for the flowsheet is ", degrees_of_freedom(m))
print("--------------------------------------------------------------------")
solver.solve(m, tee=tee)
#
from idaes.core.util.units_of_measurement import convert_quantity_to_reporting_units,report_quantity
# Print reports
for i in m.fs.component_objects(Block):
if isinstance(i, UnitModelBlockData):
i.report()
# Converting units for readability
print(-1*value(units.convert(m.fs.turbine.work_mechanical[0],units.kW))\
-1*value(units.convert(m.fs.main_compressor.work_mechanical[0],units.kW))\
-1*value(units.convert(m.fs.bypass_compressor.work_mechanical[0],units.kW)),units.kW)
return m
if __name__ == "__main__":
m = main()
2024-05-09 18:37:25 [INFO] idaes.init.fs.boiler.control_volume: Initialization Complete
---------------------------------------------------------------------------
ApplicationError Traceback (most recent call last)
Cell In[4], line 213
210 return m
212 if __name__ == "__main__":
--> 213 m = main()
Cell In[4], line 108, in main()
105 m.fs.boiler.outlet.temperature.fix(893.15) # Turbine inlet T = 620 C
106 m.fs.boiler.deltaP.fix(-0.21)
--> 108 m.fs.boiler.initialize(outlvl=outlvl)
110 propagate_state(m.fs.s01)
112 m.fs.turbine.ratioP.fix(1/3.68)
File ~/checkouts/readthedocs.org/user_builds/idaes-examples/envs/latest/lib/python3.8/site-packages/idaes/core/base/unit_model.py:540, in UnitModelBlockData.initialize(blk, *args, **kwargs)
537 c.deactivate()
539 # Remember to collect flags for fixed vars
--> 540 flags = blk.initialize_build(*args, **kwargs)
542 # If costing block exists, activate and initialize
543 for c in init_order:
File ~/checkouts/readthedocs.org/user_builds/idaes-examples/envs/latest/lib/python3.8/site-packages/idaes/core/base/unit_model.py:601, in UnitModelBlockData.initialize_build(blk, state_args, outlvl, solver, optarg)
598 # ---------------------------------------------------------------------
599 # Solve unit
600 with idaeslog.solver_log(solve_log, idaeslog.DEBUG) as slc:
--> 601 results = opt.solve(blk, tee=slc.tee)
603 init_log.info_high(
604 "Initialization Step 2 {}.".format(idaeslog.condition(results))
605 )
607 # ---------------------------------------------------------------------
608 # Release Inlet state
File ~/checkouts/readthedocs.org/user_builds/idaes-examples/envs/latest/lib/python3.8/site-packages/pyomo/opt/base/solvers.py:534, in OptSolver.solve(self, *args, **kwds)
531 def solve(self, *args, **kwds):
532 """Solve the problem"""
--> 534 self.available(exception_flag=True)
535 #
536 # If the inputs are models, then validate that they have been
537 # constructed! Collect suffix names to try and import from solution.
538 #
539 from pyomo.core.base.block import BlockData
File ~/checkouts/readthedocs.org/user_builds/idaes-examples/envs/latest/lib/python3.8/site-packages/pyomo/opt/solver/shellcmd.py:140, in SystemCallSolver.available(self, exception_flag)
138 if exception_flag:
139 msg = "No executable found for solver '%s'"
--> 140 raise ApplicationError(msg % self.name)
141 return False
142 return True
ApplicationError: No executable found for solver 'ipopt'