project

Eutectic Freeze Crystallisation

Expert(s):
Erwin Beerendonk BSc

  • Start date
    01 Jul 2013
  • End date
    31 Dec 2016
  • collaborating partners
    EFC, Evides Industriewater, Hatenboer Water and KWR Watercycle Research Institute

The objective of this project is to determine the feasibility of EFC for the treatment of regenerant from ion exchange – as applied in DOC removal/decolouration and softening (especially drinking water and water-related industrial applications) – through research on a semi-industrial, pilot scale under practical conditions at several locations.

Technology

EFC is a promising technique for the processing of concentrated saline solutions. Ideally, the salt concentration is close to the saturation limit; at lower levels, a concentration step is needed to achieve the ideal level. The technique has been proven on a small scale. The anticipated cost level is attractive when compared to the alternatives, such as evaporation followed by crystallisation. The next steps for the further development of the EFC technology are research under practical conditions, research into further scaling-up in a continuous process, and definition of the implementation possibilities from the end-user’s perspective.

This TKI projects is connected to the ongoing project aimed at EFC modelling via TTIW / Wetsus (participants: Vewin, Evides Industriewater (EIW) and EFC Separations).

Challenge

This TKI project delivers four results:

  1. Inventory of water-related (industrial) applications of IEX, and a determination of the possible operating window to carry out the semi-industrial pilot. The possible reuse and valorisation of residuals is also examined.
  2. Realisation of a semi-industrial pilot installation.
  3. Experimental assessment on-site, based on the pilot, of the operation of EFC under practical conditions.
  4. On the basis of the results, establishment of the feasibility of EFC for specified applications compared to alternative methods.

Solution

The inventory of water-related (industrial) applications of IEX as well as the determination of design conditions of the semi-industrial pilot have been concluded. The projected pilot will be used for the recovery of the excess salt (NaCl) regenerant. The salt crystallises at the eutectic point of -21°C and 23.3%. The pilot is to be equipped with an improved crystalliser with a capacity of 50-300 kg of ice per hour, and a new settler which enables a more efficient separation of the ice and salt crystals. During the pilot provisions are also to be taken to wash both the ice and salt crystals to improve the quality of the recovered water and salt.

The pilot has been realised by EFC and installed and made operational at the EIW location DWP Botlek. The pilot will be extensively tested at this location using the spent regenerant from DWP Botlek. The plan is to have the pilot tested at a second location; the feasibility study will then be finalised.