Feed Block

Feed Blocks are used to represent sources of material in Flowsheets. These can be used to determine the full state of a material (including equilibrium) based on a sufficient set of state variables prior to being passed to the first unit operation.

Degrees of Freedom

The degrees of freedom of Feed blocks depends on the property package being used and the number of state variables necessary to fully define the system. Users should refer to documentation on the property package they are using.

Model Structure

Feed Blocks consists of a single HoldupStatic Block (named holdup), each with one Outlet Port (named outlet).

Construction Arguments

The Feed model has the following construction arguments:

  • property_package - property package to use when constructing Property Block for the Feed Block (default = ‘use_parent_value’). This is provided as a Property Parameter Block by the Flowsheet when creating the model. If a value is not provided, the Holdup Block will try to use the default property package if one is defined.
  • property_package_args - set of arguments to be passed to the Property Block when they are created.
  • outlet_list - list of names to be passed to the build_outlets method (default = None).
  • num_outlets - number of outlets argument to be passed to the build_outlets method (default = None).

Additionally, Feed Blocks have the following construction arguments which are passed to the Holdup Block for determining which terms to construct in the balance equations. Feed Blocks do not support dynamic = True.

Argument Default Value
material_balance_type ‘component_phase’
energy_balance_type ‘total’
momentum_balance_type ‘total’
dynamic False (cannot be True)
include_holdup False
has_rate_reactions False
has_equilibrium_reactions False
has_phase_equilibrium False
has_mass_transfer False
has_heat_transfer False
has_work_transfer False
has_pressure_change False

Additional Methods

Feed Blocks define three additional methods useful for defining and interpreting the feed conditions. These methods are documented below in the FeedData Class section;

  1. display()
  2. fix()
  3. unfix()

Additional Constraints

Feed Blocks write no additional constraints to the model.

Variables

Feed blocks add no additional Variables.

FeedData Class

class idaes.models.feed.FeedData(component)[source]

Standard Feed Block Class

build()[source]

Begin building model (pre-DAE transformation).

Parameters:None
Returns:None
display(display_block=False, ostream=None, prefix='')[source]

Display the contents of Feed unit.

Parameters:
  • display_block – indicates whether to display the entire Block
  • object (default = False) –
  • ostream – output stream (default = None)
  • prefix – str to append to each line of output (default = ‘’)
Returns:

None

fix(var, comp=None, value=None, time=None)[source]

Method for fixing Vars in Feed Block.

Parameters:
  • var – variable name to be fixed (as str)
  • comp – index of var to be fixed (if applicable, default = None)
  • value – value to use when fixing var (default = None)
  • time – list of time points at which to fix var (can be float, int
  • list) (or) –
Returns:

None

post_transform_build()[source]

Continue model construction after DAE transformation.

Parameters:None
Returns:None
unfix(var, comp=None, time=None)[source]

Method for unfixing Vars in Feed Block.

Parameters:
  • var – variable name to be unfixed (as str)
  • comp – index of var to be unfixed (if applicable, default = None)
  • time – list of time points at which to unfix var (can be float, int
  • list) (or) –
Returns:

None