Some questions regarding aromatic extraction (extractive distillation); I welcome advice from those with more experience.

I’m not sure what kind of partition you mean at the bottom of the extraction tower; it’s definitely not a tower plate or a filtering screen, right? In the system, the solvent flow rate is monitored using a flow meter; as for the total amount, it is estimated based on the total amount of solvent used at startup and the amount lost. The total amount of solvent used can be calculated from the difference in liquid levels before and after the solvent tank, along with the volume of the tank. Under ideal conditions, the water content in the extraction system should not be lost; the amount of water circulating mainly affects the amount of solute present in the non-aromatic compounds. In other words, the sulfur content decreases as the washing ratio increases, and the regenerated solvent also needs to be carried away by steam. However, an excessive water circulation rate can also lead to operational difficulties and excessive load; the specific values depend on the adjustment of the feed components.

The function of the baffle is to separate the liquid drawn from the bottom of the tower from the heated medium that is returned to that same bottom area; this is what is commonly referred to as the high liquid level and the low liquid level in distillation and extraction towers, as there is a liquid level gauge on each side. The total amount of solvent is the value recorded during calibration at the start of operation, when liquid is supplied to the system from the fresh solvent tank. There are extraction distillations with solvents that contain water and those without water. For solvents without water, xylene is often used as a co-solvent; the solvent that contains water is steam used for stripping. Its functions are: 1) to act as stripping steam in the extraction tower, 2) to increase the selectivity of the solvent, and 3) when the solvent containing water enters the solvent regeneration tower, the water condenses at the top of the tower, which helps maintain negative pressure in the tower.

The partition he mentioned is probably the one in the liquid collection tank at the bottom of the tower – that plate used to collect liquid in the heat exchanger. To achieve a more precise level of solvent filling, it’s possible only by estimating based on the drop in liquid level when a new solvent tank is added. The water content in the lean solvent ranges from 0.5 to 1.0 weight percent; generally, keeping this value around 0.6 is sufficient, as it affects the selectivity of the solvent. What is adjusted occasionally is the amount of stripping steam~ it decreases a bit as a result of non-aromatic and mixed aromatic losses~