Abstract: In a rotatable filter, such as a disk filter, for separating solid particles from a liquid mixture, in which a filter material (3) is partially immersed, a cake-removal member (11) is designed to take off a layer of the formed cake of solid particles from the filter material, so that a liquid-permeable coating, which itself acts as a filter medium, is left on the filter material which is moved down into the liquid mixture which is to be separated. According to the invention, for renewing the coating a spraying apparatus (13-17) is designed to spray jets of liquid in at least one spray zone (18), through which only a part of the filter material passes upwards during the rotating movement of the filter material, so that the whole cake of coarse particles, including the coating, is removed from the part of the filter material by the jets of liquid.

Abstract: A device for cleaning caustic liquor mixtures containing lime, comprising a closed chamber 7 for the caustic liquor mixture to be cleaned with an upper horizontal wall 5, to which a number of hollow filter elements 8 are attached. The filter elements extend downwardly in the chamber and communicate with the latter via a great number of filtrate holes 9 in the filter elements. Each filter element is provided with a filter material 10, which covers the filtrate holes. According to the invention, the filtrate holes 9 are arranged below a horizontal plane P, which is situated below and at a distance from the horizontal wall 5 such that during operation gas is enclosed between the wall and the uncleaned caustic liquor mixture. As a result the caustic liquor mixture in the chamber is prevented from contacting the wall 5, which counteracts the formation of permanent tight layers of lime on the filter material.

Abstract: A method for controlling a filtration assembly wherein the amount of medium introduced into the filtration assembly is constant, even though the filterability of the medium or the condition of the filters has changed. The working cycle of the filtration assembly changes when the pressure difference across the filter mesh increases over a certain period of time. The control system is capable of distinguishing between the filterability of the medium introduced and the condition of the filter mesh.