Method and apparatus for separating a substance from a liquid mixture by fractional crystallization

Abstract

The crystalliser (70) has an inlet (77) for the crystal medium to be fractionated and an outlet (84) from which the mother liquor followed by the molten crystals can be withdrawn at the end of the crystallisation process. During the crystallisation process, a number of tubes (75) closed at the top can be supplied from above with a trickling film of liquid mixture. The tubes are internally supplied with a trickling film of a liquid heat exchange medium used for cooling. The liquid heat exchange medium is supplied via a riser (87), and a medium distributor (92) guides the flow of medium heat exchange under the distribution tray (81). The pressure of the evaporating coolant in the medium chamber (80), to which the inner space of the tubes also belongs, is controlled, thus controlling the temperature of the wall of the tubes where crystallisation takes place. In order to melt the crystals, gaseous heat exchange medium is introduced through a spigot (96) into the crystalliser under controlled pressure. The crystalliser can serve selectively as an evaporator or as a condenser in a refrigeration machine, in order to use both cooling energy and waste heat from the machine.

Dependencies are inferred from the claim text.