# Steady-State condition for CADET Process

**URL:** <https://forum.cadet-web.de/t/steady-state-condition-for-cadet-process/989>\
**Category:** Chromatography Modeling\
**Tags:** modeling\
**Created:** [July 10, 2024, 7:41pm UTC](https://forum.cadet-web.de/t/steady-state-condition-for-cadet-process/989 "2024-07-10T19:41:23Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![fmadanisani](https://forum.cadet-web.de/letter_avatar_proxy/v4/letter/f/c2a13f/32.png) [@fmadanisani](https://forum.cadet-web.de/u/fmadanisani)\
**Post date:** [July 10, 2024, 7:41pm UTC](https://forum.cadet-web.de/t/steady-state-condition-for-cadet-process/989/1 "2024-07-10T19:41:23Z")

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Hi,

I would like to know if we can use the CADET Process in a steady-state condition, meaning without the effect of time, or in other words, at infinite time when the simulated moving bed reaches steady-state.

Thank you,  
Fazlollah

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**Author:** ![ronald.jaepel](https://forum.cadet-web.de/user_avatar/forum.cadet-web.de/ronald.jaepel/32/986_2.png) [@ronald.jaepel](https://forum.cadet-web.de/u/ronald.jaepel)\
**Post date:** [July 10, 2024, 7:44pm UTC](https://forum.cadet-web.de/t/steady-state-condition-for-cadet-process/989/2 "2024-07-10T19:44:31Z")

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Hi Fazlollah,

welcome to the forum!

You can use CADET-Process for that. Here’s the documentation for [cyclic stationarity](https://cadet-process.readthedocs.io/en/latest/user_guide/simulator.html#stationarity-guide) and [steady state recycling](https://cadet-process.readthedocs.io/en/latest/examples/recycling/mrssr_process.html). If you have further questions feel free to let me know.

Best wishes,  
Ron

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**Author:** ![fmadanisani](https://forum.cadet-web.de/letter_avatar_proxy/v4/letter/f/c2a13f/32.png) [@fmadanisani](https://forum.cadet-web.de/u/fmadanisani)\
**Post date:** [July 11, 2024, 6:49am UTC](https://forum.cadet-web.de/t/steady-state-condition-for-cadet-process/989/3 "2024-07-11T06:49:12Z")

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Thank you for your reply. I understand that we can specify the cycle numbers or different criteria to reach/define a steady-state condition. However, all the equations are still solved in a time-dependent manner. Is there a mode in CADET Process where we can remove the time dependency from the mass balance equations (i.e., assume dc/dt = 0) to reduce simulation times? This would be extremely helpful for complex SMB systems with multiple columns.

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**Author:** ![j.schmoelder](https://forum.cadet-web.de/user_avatar/forum.cadet-web.de/j.schmoelder/32/93_2.png) [@j.schmoelder](https://forum.cadet-web.de/u/j.schmoelder)\
**Post date:** [July 11, 2024, 6:54am UTC](https://forum.cadet-web.de/t/steady-state-condition-for-cadet-process/989/4 "2024-07-11T06:54:07Z")

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Hi Fazlollah,

no, we currently do not provide such solutions and I’m not even sure how this would work for some very limited cases with strong assumptions (e.g. linear isotherms, rapid equilibrium, no dispersion etc). Otherwise, \frac{\partial c}{\partial t} is a function of time and space and is not equal to 0.

But maybe we’re missing something, so if you have additional information, we could have a look.

Best

Johannes

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**Author:** ![lieres](https://forum.cadet-web.de/user_avatar/forum.cadet-web.de/lieres/32/1238_2.png) [@lieres](https://forum.cadet-web.de/u/lieres)\
**Post date:** [July 11, 2024, 8:00pm UTC](https://forum.cadet-web.de/t/steady-state-condition-for-cadet-process/989/5 "2024-07-11T20:00:30Z")

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There are several ways to directly calculate the cyclic steady state without following the exact trajectory over time, e.g. as described by [He at al. (2018)](https://doi.org/10.1016/j.compchemeng.2017.12.022). However, these methods are not (yet) implemented in CADET-Process.