Apparatus and method for the concentration of a liquid by evaporation

Apparatus for the concentration of a liquid by evaporation comprising

• (a) a heat exchanger having a plurality of upwardly extending riser tubes for flow of the liquid being treated, which tubes have open upper and lower ends and in use are contacted by a relatively hot medium for heat transfer to the liquid being treated,
• (b) upper and lower chambers respectively above and below the heat exchanger, the riser tubes opening at respectively their upper and lower ends into said upper and lower chambers, the upper chamber having a base and the riser tubes extending above that base,
• (c) a granular mass which is fluidizable in use by the flow of the liquid being treated so as to occupy at least the said riser tubes,
• (d) means for vapour collection and discharge from the upper chamber,
• (e) at least one return conduit for passage of the liquid being treated and the granular mass from the upper chamber to the lower chamber, which return conduit is connected into the upper and lower chambers in each case at a lower level than the opening of the riser tubes into the respective chamber, and
• (f) supply and discharge connections for the liquid being teated located at levels lower than the opening of the riser tubes into the upper chamber.