Chemical Addition (ZO)

Model Type

This unit model is formulated as a pass-through model form. See documentation for pass-through Helper Methods.

Electricity Consumption

The constraint used to calculate energy consumption is described in the Additional Constraints section below. More details can be found in the unit model class.

Costing Method

Costing is calculated using the cost_chemical_addition() method. For full details on costing, see documentation for the zero-order costing package.

Additional Variables

Description	Variable Name	Units
Dosing rate of chemical	chemical_dosage	\(mg/l\)
Mass density of chemical solution	solution_density	\(kg/m^3\)
Mass fraction of chemical in solution	ratio_in_solution	\(dimensionless\)
Volumetric flow rate of chemical solution	chemical_flow_vol	\(m^3/s\)
Electricity consumption of unit	electricity	\(kW\)

Additional Constraints

Description	Constraint Name
None	chemical_flow_constraint
Constraint for electricity consumption based on pump flowrate.	electricity_consumption

Class Documentation

This module contains a zero-order representation of a chemical addition unit operation.

class watertap.unit_models.zero_order.chemical_addition_zo.ChemicalAdditionZO(*args, **kwds)

Parameters:

• rule (function) – A rule function or None. Default rule calls build().

• concrete (bool) – If True, make this a toplevel model. Default - False.

• ctype (class) –

  Pyomo ctype of the block. Default - pyomo.environ.Block

  Config args

  dynamic

  All zero-order models are steady-state only

  has_holdup

  Zero order models do not include holdup

  property_package

  Property parameter object used to define property calculations, default - useDefault. Valid values: { useDefault - use default package from parent model or flowsheet, PhysicalParameterObject - a PhysicalParameterBlock 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.}

  database

  An instance of a WaterTAP Database to use for parameters.

  process_subtype

  Process subtype to use when looking up parameters from database.

  isothermal

  Isothermal assumption, or ignore temperature variables in unit. Default=True

  isobaric

  Isobaric assumption, or ignore pressure variables in unit. Default=True

• initialize (dict) – ProcessBlockData config for individual elements. Keys are BlockData indexes and values are dictionaries with config arguments as keys.

• 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 override the default behavior of matching the BlockData index exactly to the index in initialize.

Returns:

(ChemicalAdditionZO) New instance

class watertap.unit_models.zero_order.chemical_addition_zo.ChemicalAdditionZOData(component)

Zero-Order model for a chemical addition unit operation.

build()

General build method for UnitModelBlockData. This method calls a number of sub-methods which automate the construction of expected attributes of unit models.

Inheriting models should call super().build.

Parameters:

None –

Returns:

None

static cost_chemical_addition(blk, number_of_parallel_units=1)

General method for costing chemical addition processes. Capital cost is based on the mass flow rate of chemical added. This method also registers the chemical flow and electricity demand as costed flows. :param number_of_parallel_units: number_of_parallel_units parallel units (default: 1) :type number_of_parallel_units: int, optional