Unit#

class Unit(ID='', ins=None, outs=(), thermo=None, **kwargs)[source]#

Abstract class for Unit objects. Child objects must contain _run, _design and _cost methods to estimate stream outlets of a Unit and find design and cost information.

Parameters:

ID (str, optional) – A unique identification. If ID is None, unit will not be registered in flowsheet. By default, a unique ID will be chosen.
ins (Stream], optional) – Inlet streams or IDs to initialize inlet streams. If empty tuple, streams with default IDs will be created. By default, streams will be missing.
outs (Stream], optional) – Outlet streams or IDs to initialize outlet streams. By default, streams with unique IDs will be created. If None, streams will be missing.
thermo (Thermo, optional) – Thermo object to initialize inlet and outlet streams. Defaults to settings.thermo.

Notes

The free on board (f.o.b.) purchase costs and installed equipment costs (i.e. bare-module cost) for each item in the baseline_purchase_costs dictionary and in auxiliary units are automatically added to the purchase_costs and installed_costs dictionaries.

As explained in [1], the f.o.b. purchase cost is given by:

\[C_{P} = C_{Pb}F_{D}F_{P}F_{M}\]

And the installed equipment cost is given by:

\[C_{BM} = C_{Pb} (F_{BM} + F_{D}F_{P}F_{M} - 1)\]

Where:

\(C_{Pb}\): Baseline purchase cost.
\(F_{BM}\): Bare module factor.
\(F_{D}\): Design factor.
\(F_{P}\): Pressure factor.
\(F_{M}\): Material factor.

Values for the bare-module, design, pressure, and material factors of each equipment should be stored in the F_BM, F_D, F_P, and F_M dictionaries.

Examples

Creating a Unit

-pipe- notation

Inheriting from Unit

References

_units: dict[str, str] = {}#: class-attribute Units of measure for design_results dictionary.

_F_BM_default: dict[str, float] = {}#: class-attribute Default bare-module factors for each purchase cost item. Items in this dictionary are copied to the F_BM attribute during initialization.

_materials_and_maintenance: frozen:py:class:set[str] = frozenset({})#: class-attribute Cost items that need to be summed across operation modes for flexible operation (e.g., filtration membranes).

auxiliary_unit_names: tuple[str, ...] = ()#: class-attribute Name of attributes that are auxiliary units. These units will be accounted for in the purchase and installed equipment costs without having to add these costs in the baseline_purchase_costs dictionary. Heat and power utilities are also automatically accounted for.

_N_ins: int = 1#: class-attribute Expected number of inlet streams. Defaults to 1.

_N_outs: int = 1#: class-attribute Expected number of outlet streams. Defaults to 1

_ins_size_is_fixed: bool = True#: class-attribute Whether the number of streams in ins is fixed.

_outs_size_is_fixed: bool = True#: class-attribute Whether the number of streams in outs is fixed.

line: str = 'Unit'#: class-attribute Name denoting the type of Unit class. Defaults to the class name of the first child class

_default_equipment_lifetime: int | dict[str, int] = {}#: class-attribute Lifetime of equipment. Defaults to lifetime of production venture. Use an integer to specify the lifetime for all items in the unit purchase costs. Use a dictionary to specify the lifetime of each purchase cost item.

_graphics: :py:class:`~biosteam.Unit`Graphics = UnitGraphics(node={'shape': 'box', 'style': 'filled', 'gradientangle': '0', 'width': '0.6', 'height': '0.6', 'orientation': '0.0', 'peripheries': '1', 'margin': 'default', 'fontname': 'Arial'}, edge_in=({'headport': 'c'},), edge_out=({'tailport': 'c'},))#: class-attribute Settings for diagram representation. Defaults to a box with the same number of inlet and outlet edges as _N_ins and _N_outs.

_run = AbstractMethod#: Run mass and energy balances and update outlet streams (without user-defined specifications).

_design = AbstractMethod#: Add design requirements to the design_results dictionary.

_cost = AbstractMethod#: Add itemized purchase costs to the baseline_purchase_costs dictionary.

heat_utilities: list[HeatUtility, ...]#: All heat utilities associated to unit. Cooling and heating requirements are stored here (including auxiliary requirements).

power_utility: PowerUtility#: Electric utility associated to unit (including auxiliary requirements).

F_BM: dict[str, float]#: All bare-module factors for each purchase cost. Defaults to values in the class attribute _F_BM_default.

F_D: dict[str, float]#: All design factors for each purchase cost item in baseline_purchase_costs.

F_P: dict[str, float]#: All pressure factors for each purchase cost item in baseline_purchase_costs.

F_M: dict[str, float]#: All material factors for each purchase cost item in baseline_purchase_costs.

design_results: dict[str, object]#: All design requirements excluding utility requirements and detailed auxiliary unit requirements.

baseline_purchase_costs: dict[str, float]#: All baseline purchase costs without accounting for design, pressure, and material factors.

purchase_costs: dict[str, float]#: Itemized purchase costs (including auxiliary units) accounting for design, pressure, and material factors (i.e., F_D, F_P, F_M). Items here are automatically updated at the end of unit simulation.

installed_costs: dict[str, float]#: All installed costs accounting for bare module, design, pressure, and material factors. Items here are automatically updated at the end of unit simulation.

equipment_lifetime: int | dict[str, int]#: Lifetime of equipment. Defaults to values in the class attribute _default_equipment_lifetime. Use an integer to specify the lifetime for all items in the unit purchase costs. Use a dictionary to specify the lifetime of each purchase cost item.

run_after_specifications: bool#: Whether to run mass and energy balance after calling specification functions

prioritize: bool#: Whether to prioritize unit operation specification within recycle loop (if any).

parallel: dict[str, int]#: Name-number pairs of baseline purchase costs and auxiliary unit operations in parallel. Use ‘self’ to refer to the main unit. Capital and heat and power utilities in parallel will become proportional to this value.

responses: set[GenericResponse]#: Unit design decisions that must be solved to satisfy specifications. While adding responses is optional, simulations benefit from responses by being able to predict better guesses.

response(name)[source]#: Register response for convergence model prediction.

property net_power: float#: Net power consumption [kW].

property net_duty: float#: Net duty including heat transfer losses [kJ/hr].

property net_cooling_duty: float#: Net cooling duty including heat transfer losses [kJ/hr].

property net_heating_duty: float#: Net cooling duty including heat transfer losses [kJ/hr].

property feed: Stream#: Equivalent to ins[0] when the number of inlets is 1.

property inlet: Stream#: Equivalent to ins[0] when the number of inlets is 1.

property influent: Stream#: Equivalent to ins[0] when the number of inlets is 1.

property product: Stream#: Equivalent to outs[0] when the number of outlets is 1.

property outlet: Stream#: Equivalent to outs[0] when the number of outlets is 1.

property effluent: Stream#: Equivalent to outs[0] when the number of outlets is 1.

add_power_utility(power)[source]#: Add power utility [kW]. Use a positive value for consumption and a negative for production.

create_heat_utility(agent=None, heat_transfer_efficiency=None)[source]#: Create heat utility object associated to unit.

add_heat_utility(unit_duty, T_in, T_out=None, agent=None, heat_transfer_efficiency=None, hxn_ok=False)[source]#

Add utility requirement given the duty and inlet and outlet temperatures.

Parameters:

unit_duty (float) – Unit duty requirement [kJ/hr]
T_in (float) – Inlet process stream temperature [K]
T_out (float, optional) – Outlet process stream temperature [K]
agent (UtilityAgent, optional) – Utility agent to use. Defaults to a suitable agent from predefined heating/cooling utility agents.
heat_transfer_efficiency (float, optional) – Enforced fraction of heat transfered from utility (due to losses to environment).
hxn_ok (bool, optional) – Whether heat utility can be satisfied within a heat exchanger network.

define_utility(name, stream)[source]#

Define an inlet or outlet stream as a utility by name.

Parameters:

name (str) – Name of utility, as defined in settings.stream_utility_prices.
stream (Stream) – Inlet or outlet utility stream.

get_node()[source]#: Return unit node attributes for graphviz.

get_design_result(key, units)[source]#

Return design result in a new set of units of measure.

Parameters:

key (str) – Name of design result.
units (str) – Units of measure.

Examples

>>> import biosteam as bst
>>> bst.settings.set_thermo(['Water'], cache=True)
>>> feed = bst.Stream(None, Water=100)
>>> tank = bst.StorageTank(None, feed)
>>> tank.simulate()
>>> tank.get_design_result('Total volume', 'm3')
1214.19
>>> tank.get_design_result('Total volume', 'L')
1214191.0

add_specification(f=None, run=None, args=(), impacted_units=None, prioritize=None)[source]#

Add a specification.

Parameters:

f (Callable, optional) – Specification function runned for mass and energy balance.
run (bool, optional) – Whether to run the built-in mass and energy balance after specifications. Defaults to False.
args (tuple, optional) – Arguments to pass to the specification function.
impacted_units (tuple`[:py:class:`~biosteam.Unit, ...], optional) – Other units impacted by specification. The system will make sure to run itermediate upstream units when simulating.
prioritize (bool, optional) – Whether to prioritize the unit operation within a recycle loop (if any).

Examples

Process specifications