(Meth) acrylic acid and / or method of cleaning plate column that was used for the liquid to rectification processes containing ester thereof

(Meth) the plate column that was used for rectifying treating a liquid containing an acrylic compound, a basic liquid is supplied downward from above in the plate column, the column of gas in a basic liquid and countercurrent how to clean by conduction, the average gas phase difference pressure over all trays in this case is at least 0.5 mbar per tray.