proII simulates the crude oil distillation process
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It consists of a primary distillation tower, an atmospheric pressure tower, and a vacuum distillation tower. What are some tips for convergence in mediation? Thank you!
The pre-fractionator has converged, but the atmospheric tower still doesn’t converge. What can be done? Thank you!
In the atmospheric pressure column, water becomes supersaturated in the oil phase; it is likely this issue that causes the lack of convergence. I chose the BK model. How can this be resolved? Thank you
In my opinion, the trick to achieving convergence lies in using the following combinations when setting the tower’s specifications: 1. Reflux ratio + top temperature; 2. Reflux ratio + amount taken from the top of the tower or the flow rate at the top of the tower. These two approaches make it easier to achieve convergence, but they may not meet the separation requirements for your product; in such cases, you need to adjust these two parameters to meet those separation requirements. Not recommended: 1. Multiple separation requirements. Apart from this, it is recommended to use a shortcut tower first; based on the separation requirements you set (which need to be specified in the shortcut tower), calculate the theoretical number of theoretical plates, feed position, reflux ratio, etc., and then apply these values to a complex tower for distillation. Generally, using the reflux ratio and temperature specified by the shortcut tower as parameters will yield separation results that are similar to those you intended. But there are still sometimes significant differences, which need to be taken into account.
It’s quite useful; it even solved a small problem I just encountered. Thank you!
Why not try the NRTL model, which is suitable for water and organic substances?
Is there any information on combinations?
In crude oil simulation, GS can be used for the atmospheric distillation column, while BK is suitable for the vacuum distillation column; the aqueous phase should be the product formed at the top of the column
NRTL is applicable to electrolytes, but not to atmospheric and vacuum distillation! !
The fundamental reason for non-convergence lies not in the material property method. The settings of the model itself determine whether it is easy to converge. The initial stage of operation in a column is relatively simple and convergence usually occurs. In constant-pressure and reduced-pressure columns, there are side streams for product extraction as well as heat removal at intermediate stages, which makes them more complex; convergence is more difficult and requires more time for tuning. Especially when doing it for the first time, if all the heat exchange processes are taken into account, it’s definitely not something that can be completed in just a few days.
I have benefited from learning this; thank you all for sharing your experiences