Plant for cleaning caustic lye - has several, parallel-coupled, discontinuously effective filter units to separate calcium carbonate and white lye

摘要

The causticated lye is continuously cleaned to separate calcium carbonate and white lye, viz. sodium hydroxide, and for the sepn. process, involves the use of one or more filter units out of several which are parallel-coupled, and discontinuously effective. The remaining filter units are used for a cleaning sequence. The filter units each include an upper space for sepd. white lye, and a lower space for causticated lye and sepd. calcium carbonate. All or a part of the white lye in the upper space can be fed to a container by means of gas or air, and before the gas or air is allowed to pass through the filters for the cleaning sequence. The outlet for white lye is arranged in the upper space and in immediate proximity of the lower space, and an inlet for pressurised gas or air is arranged beneath the outlet and in the lower space.