A sustainable technology: Eutectic freeze crystallization - From batch laboratory to continuous industry applications

F. E. Genceli*, R. S. Gärtner, D. Trambitas, M. Rodriguez, G. J. Witkamp

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations

Abstract

Eutectic Freeze Crystallization (EFC) offers a technically and economically attractive alternative for conventional separation techniques for the recovery of dissolved salts. EFC operates around the eutectic temperature and composition of aqueous solutions, but can treat a wide variety of feed solutions. Both highly pure salt and ice crystals can be simultaneously obtained as valuable products. Theoretically 100% yield and up to 70% energy cost saving (typically 50%) can be achieved compared to triple stage evaporative crystallization. Separation of ice and salt products takes place inside the crystallizer, based on their density difference. EFC is discussed in terms of its state of the art (from 10-liters lab-scale to 250-liter industrial scale), economical evaluation (compared to triple-stage evaporation and cooling crystallization), product qualities (crystal sizes and impurity contents) and industrial applications. A complete mobile, skid mounted pilot unit for EFC applications was designed and constructed together with industrial partners, allowing the system to be easily installed and connected to an industrial plant. As a practical application, the skid mounted unit was designed for producing 130 ton/year MgSO47H2O salt with a crystallizer volume of 250-liters, and 6.83 m2/m3 cooling surface area. The particle sizes of MgSO412H2O(s) and ice crystals range from 150 to 300 μm. MgSO4.12H2O(s) is not stable above 0°C, at ambient temperature it transforms into MgSO4.7H 2O(s). The impurities in the ice are almost exclusively due to adhering liquor; the ice crystals are in general extremely pure. Washing the ice twice brings its impurity level of Mg2+ and SO4 2- to 10 and 45 ppm respectively, which makes it suitable for use as process water. The impurity level in the MgSO4.7H20 salt is below the detection limit after two times washings (≪ 1 ppm). The recovery of magnesium sulphate as hydrates from washing liquid from ex-flue gas desulphurization has payback times for conventional cooling crystallization of 5.2, for three-stage evaporative crystallization 2.7 and for EFC 2.4 years.

Original languageEnglish (US)
Title of host publicationPapers presented at
Subtitle of host publicationSustainable (Bio)Chemical Process Technology - Incorporating the 6th Intenational Conference on Process Intensification
EditorsP. Jansens, A. Stankiewicz, A. Green
Pages235-242
Number of pages8
StatePublished - Dec 1 2005
Externally publishedYes
EventSustainable (Bio)Chemical Process Technology - Incorporating the 6th Intenational Conference on Process Intensification - Delft, Netherlands
Duration: Sep 27 2005Sep 29 2005

Conference

ConferenceSustainable (Bio)Chemical Process Technology - Incorporating the 6th Intenational Conference on Process Intensification
CountryNetherlands
CityDelft
Period09/27/0509/29/05

ASJC Scopus subject areas

  • Engineering(all)

Fingerprint Dive into the research topics of 'A sustainable technology: Eutectic freeze crystallization - From batch laboratory to continuous industry applications'. Together they form a unique fingerprint.

Cite this