Temperature of heating utility agents

[yalinli2]

Hi @yoelcortes , @jiananf2 is designing an HTL system where multiple unit operations would need pretty high T/P (highest one is a hydrotreating unit at 405°C I think), but none of the UtilityAgent in biosteam can currently reach that temperature.

I'm wondering how the temperature for those agents were decided? E.g., now

>>> import biosteam as bst
>>> for ha in bst.HeatUtility.heating_agents:
...     print(ha.ID, ha.T)
low_pressure_steam 412.189
medium_pressure_steam 454.77
high_pressure_steam 508.991

were 412.189/454.77/508.991 from Perry or other books? I think there are cases where we just change the temperature, e.g., in the cornstover biorefinery:
https://github.com/BioSTEAMDevelopmentGroup/Bioindustrial-Park/blob/5cfb8f34d314412fc63490ab627473a6b69b05b2/biorefineries/cornstover/_process_settings.py#L45

    _ha = bst.HeatUtility.get_heating_agent('low_pressure_steam')
    _ha.heat_transfer_efficiency = 0.90
    _ha.T = 529.2
    _ha.P = 44e5
    _ha.regeneration_price = 0.

Thank you!

[yoelcortes]

@yalinli2, @jiananf2,

The steam pressures come from Warren Seiders's product and process design principles. The temperature is the dew point temperature. Steam utilities work by transferring heat as they condense. For temperatures above the critical point (370 C), you'll need to define another heating agent (not water) with a higher critical point... But a better option is probably to use natural gas (or any other fuel) directly. Heat utilities do not support heat transfer by combustion yet, so you'll need to hard code the energy balance and set the natural gas as an inlet stream.

Hope this helps,
Thanks!

[yoelcortes]

Also, you may also want to consider the cost of the compressor to pump air for the natural gas to combust.

[yalinli2]

sounds good thanks for the inputs! I'll let this issue open for some time till we figure out a good way to handle this and then follow up, thanks!

[yalinli2]

Just a note that Jianan has added hot oil as a new utility agent - we'll submit a PR when we are comfortable with the assumptions and clean up codes.

[yalinli2]

Just to see the status on this, @jiananf2 do you want to add a new heating agents? Thanks!