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Winterization – dewaxing

Winterization is a thermo-mechanical process in which solids are crystallized under controlled temperature conditions. The next stage is their mechanical separation. The process is used for oils that produce turbidity below 5°C, such as cotton and sunflower oil. The cause of turbidity may be an increased content of saturated triglycerides or the presence of waxes. For example, sunflower oil contains waxes , so the term dewaxing is used here.

The equipment works on the principle of crystallization of waxes with the aid of a crystallizing agent while gradually cooling the oil, followed by filtration on a horizontal plate filter.

The technology works continuously and is fully automated.

Description of the process:

The oil must be cooled in the recuperative exchanger and to the desired temperature in the cooling exchanger.

Prior to entering the winterizer, the mixture of the crystallizing agent and oil is dispensed through a static mixer. This mixture is prepared in an expeller-equipped vessel with an automatic silica feeder. The mixture is pumped into the static mixer before entering the winterizer.

While being lightly stirred, the oil is gradually cooled and flows through a crystallizer where wax crystals grow with the help of the added crystallizing agent and low temperature.

Next, the oil is pumped into the expeller-equipped vessel before filtration, where the oil mixture mixed with silica is added by a separate pump from the same vessel that also goes into the winterizer. The oil and blend ratio is controlled automatically by flow meters.

After winterization, the oil required for the filtration cycle is collected. Thereafter, filtration proceeds according to the following steps:

  1. Filling
  2. Accumulation
  3. Filtration
  4. Extrusion
  5. Drying
  6. Regeneration

The filtration process is automatic, except the regeneration step, which must be done manually. Therefore, vertical filters that cannot be shaken (cleaned) cannot be used, as the wax filter cake is very sticky.

It is also not possible to blow steam through the filter because the crystallized waxes would dissolve.

A bag filter is located in the pipe behind the automatic filter, which is designed to capture any small debris from the main filter or if the main filter is damaged.

Winterization – line for production of edible oil, capacity 10 000 t/year, Croatia