METHOD FOR THE REVERSE-OSMOSIS SEPARATION OF SALT CRYSTALS FROM MINERALISED WATER, DEVICE FOR REALISING THE SAME, MEMBRANE INSTALLATION AND MEMBRANE APPARATUS

摘要

The present invention relates to methods for freshening and desalting mineralised natural water or waste water. This invention more precisely relates to a method for the reverse-osmosis separation of salt crystals from mineralised water, as well as to a device for realising said method. This method involves supplying starting water under pressure into a membrane installation comprising a membrane apparatus. A permeate and a concentrate are obtained from the starting at the outlet of the membrane installation, wherein said concentrate is cooled down first in a heat exchanger and then in a crystalliser provided with a cooling system, the heat generated being discharged towards a cold source. The cooled concentrate is further fed into a separator in order to separate the crystals in the form of a dry product, the remaining solution being mixed back with the starting water by feeding it through a heat exchanger. The membrane installation includes sand filters, intermediate vessels with microfiltres, a high-pressure pump as well as membrane apparatus, wherein the installation includes at least three pairs of sand filters and intermediate vessels. The membrane apparatus are connected to each other in parallel and their number is at least equal to two. This installation also includes a chemical reactant vessel connected to the pump for supplying the starting mineralised water through a dosing pump. The membrane apparatus includes a body in which a plurality of membrane elements are provided together with filtrate discharge channels and connection pegs arranged between said membrane elements. The apparatus further includes covers provided with ducts for supplying the starting mineralised liquid and for discharging the permeate and the concentrate.