Plug Flow Reactor¶
The IDAES Plug Flow Reactor (PFR) model represents a unit operation where a material stream passes through a linear reactor vessel whilst undergoing some chemical reaction(s). This model requires modeling the system in one spatial dimension.
Degrees of Freedom¶
PFRs generally have at least 2 degrees of freedom.
Typical fixed variables are:
- 2 of reactor length, area and volume.
Model Structure¶
The core PFR unit model consists of a single ControlVolume1DBlock (named control_volume) with one Inlet Port (named inlet) and one Outlet Port (named outlet).
Variables¶
PFR units add the following additional Variables:
| Variable | Name | Notes |
|---|---|---|
| \(L\) | length | Reference to control_volume.length |
| \(A\) | area | Reference to control_volume.area |
| \(V\) | volume | Reference to control_volume.volume |
| \(Q_{t,x}\) | heat | Only if has_heat_transfer = True, reference to holdup.heat |
| \(\Delta P_{t,x}\) | deltaP | Only if has_pressure_change = True, reference to holdup.deltaP |
Constraints¶
PFR units write the following additional Constraints at all points in the spatial domain:
\[X_{t,x,r} = A \times r_{t,x,r}\]
where \(X_{t,x,r}\) is the extent of reaction of reaction \(r\) at point \(x\) and time \(t\), \(A\) is the cross-sectional area of the reactor and \(r_{t,r}\) is the volumetric rate of reaction of reaction \(r\) at point \(x\) and time \(t\) (from the outlet StateBlock).
PFR Class¶
-
class
idaes.unit_models.plug_flow_reactor.PFR(*args, **kwargs)¶ Parameters: - rule (function) – A rule function or None. Default rule calls build().
- concrete (bool) – If True, make this a toplevel model. Default - False.
- ctype (str) – Pyomo ctype of the block. Default - “Block”
- default (dict) –
Default ProcessBlockData config
- Keys
- dynamic
- Indicates whether this model will be dynamic or not, default = useDefault. Valid values: { useDefault - get flag from parent (default = False), True - set as a dynamic model, False - set as a steady-state model.}
- has_holdup
- Indicates whether holdup terms should be constructed or not. Must be True if dynamic = True, default - False. Valid values: { True - construct holdup terms, False - do not construct holdup terms}
- material_balance_type
- Indicates what type of mass balance should be constructed, default - MaterialBalanceType.componentPhase. Valid values: { MaterialBalanceType.none - exclude material balances, MaterialBalanceType.componentPhase - use phase component balances, MaterialBalanceType.componentTotal - use total component balances, MaterialBalanceType.elementTotal - use total element balances, MaterialBalanceType.total - use total material balance.}
- energy_balance_type
- Indicates what type of energy balance should be constructed, default - EnergyBalanceType.enthalpyTotal. Valid values: { EnergyBalanceType.none - exclude energy balances, EnergyBalanceType.enthalpyTotal - single enthalpy balance for material, EnergyBalanceType.enthalpyPhase - enthalpy balances for each phase, EnergyBalanceType.energyTotal - single energy balance for material, EnergyBalanceType.energyPhase - energy balances for each phase.}
- momentum_balance_type
- Indicates what type of momentum balance should be constructed, default - MomentumBalanceType.pressureTotal. Valid values: { MomentumBalanceType.none - exclude momentum balances, MomentumBalanceType.pressureTotal - single pressure balance for material, MomentumBalanceType.pressurePhase - pressure balances for each phase, MomentumBalanceType.momentumTotal - single momentum balance for material, MomentumBalanceType.momentumPhase - momentum balances for each phase.}
- has_equilibrium_reactions
- Indicates whether terms for equilibrium controlled reactions should be constructed, default - True. Valid values: { True - include equilibrium reaction terms, False - exclude equilibrium reaction terms.}
- has_phase_equilibrium
- Indicates whether terms for phase equilibrium should be constructed, default = False. Valid values: { True - include phase equilibrium terms False - exclude phase equilibrium terms.}
- has_heat_of_reaction
- Indicates whether terms for heat of reaction terms should be constructed, default - False. Valid values: { True - include heat of reaction terms, False - exclude heat of reaction terms.}
- has_heat_transfer
- Indicates whether terms for heat transfer should be constructed, default - False. Valid values: { True - include heat transfer terms, False - exclude heat transfer terms.}
- has_pressure_change
- Indicates whether terms for pressure change should be constructed, default - False. Valid values: { True - include pressure change terms, False - exclude pressure change terms.}
- property_package
- Property parameter object used to define property calculations, default - useDefault. Valid values: { useDefault - use default package from parent model or flowsheet, PropertyParameterObject - a PropertyParameterBlock object.}
- property_package_args
- A ConfigBlock with arguments to be passed to a property block(s) and used when constructing these, default - None. Valid values: { see property package for documentation.}
- reaction_package
- Reaction parameter object used to define reaction calculations, default - None. Valid values: { None - no reaction package, ReactionParameterBlock - a ReactionParameterBlock object.}
- reaction_package_args
- A ConfigBlock with arguments to be passed to a reaction block(s) and used when constructing these, default - None. Valid values: { see reaction package for documentation.}
- length_domain_set
- A list of values to be used when constructing the length domain of the reactor. Point must lie between 0.0 and 1.0, default - [0.0, 1.0]. Valid values: { a list of floats}
- transformation_method
- Method to use to transform domain. Must be a method recognised by the Pyomo TransformationFactory, default - “dae.finite_difference”.
- transformation_scheme
- Scheme to use when transformating domain. See Pyomo documentation for supported schemes, default - “BACKWARD”.
- finite_elements
- Number of finite elements to use when transforming length domain, default - 20.
- collocation_points
- Number of collocation points to use when transforming length domain, default - 3.
- initialize (dict) – ProcessBlockData config for individual elements. Keys are BlockData indexes and values are dictionaries described under the “default” argument above.
- idx_map (function) – Function to take the index of a BlockData element and return the index in the initialize dict from which to read arguments. This can be provided to overide the default behavior of matching the BlockData index exactly to the index in initialize.
Returns: (PFR) New instance