Problems with the slurry in the catalytic fractionation tower and the internals in the reprocessing tower
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See attached figure: Is the 1st refinery extraction a full extraction? It’s not all drawn out – how can it be returned to the slurry washing section in the re-refining process? Are the trays at the upper part of the tower where the oil slurry returns a blind tray? Why use a toothed weir?
Semi-extraction re-refining means returning the oil slurry to the section above the tower. The oil slurry rises to the upper trays; we are using floating valve trays, and the toothed weirs are used to distribute the washing oil slurry evenly.
Re-refining oil extraction is full extraction. It’s a problem with the drawing; looking at the position of the reflux back to the tower, the liquid dropping section on the return tray isn’t indicated in the schematic diagram.
Is the 1st refining extraction a complete extraction? It’s not all drawn out – how can it be returned to the slurry washing section in the re-refining process? Answer: It is completely extracted; everything is distilled from the 3rd tray. One path leads back to the 2nd tray as a liquid-phase reflux in the re-refining tower, while the other path goes to the second intermediate stage. Re-refined oil is not returned directly to the slurry washing section. Are the trays at the upper part of the tower where the oil slurry returns a blind tray? Why use a toothed weir? Answer: What is a blind tray? The toothed weir should be a distributor.
The recycle stream at the top of the fractionation tower, as well as the intermediate recycle oil collection tank, are known as blind trays; these trays have vapor lift holes.
We call this an oil collection tank; it is not included in the count of tray numbers.
This layer does not have the function of vapor-liquid exchange, nor can it facilitate mass or heat transfer; therefore, it is not included in the count of tray numbers.