Application of Centrifuge in Wine Processing

1. Preface

The centrifuges are widely used in chemical, petroleum, wine making, pharmaceutical, mineral processing, coal, water treatment and shipping. According to the working principle, there are two kinds of centrifuges: centrifugal filtration type and centrifugal sedimentation type.

1.1 Centrifugal Filtration

Under the action of centrifugal force, the centrifugal pressure is applied to the filter medium to separate the suspensions, the larger particles are retained on the surface of the filter medium, so as to realize the effective separation of solid and liquid.

1.2 Centrifugal Sedimentation

Centrifugal sedimentation refers to the rapid settlement of different density of suspensions to separate the solid and liquid. Generally, there is a rotating cylinder in the machine, which is driven by the motor to achieve high-speed rotation. This cylinder is called drum.

2. Classification of Centrifuge

(1) According to the separation factor, the centrifuges can be divided into constant speed centrifuge (<3000), high speed centrifuge (3000-5000) and ultra-high speed centrifuge (> 5000). In wine production, the centrifuge with separation factor of 5000-8000 is generally used for grape juice clarification. And the centrifuge with separation factor of 14000-15000 is generally used for wine clarification.

(2) According to the position of the rotating shaft, the centrifuges can be divided into vertical centrifuge and horizontal centrifuge. The vertical centrifuges are widely used in wine production in China, the maximum solid content is generally no more than 5%, and the minimum diameter of separable solid particles is 0.5 micrometer. The horizontal centrifuges are rarely used in wine production, but mostly used in sewage treatment, the maximum solid content can be treated up to 60%.

3. Principle of Centrifuge

The solid which in not dissolved in the liquid is separated by the centrifugal force of high speed rotation. The centrifugal force is directly proportional to the rotating speed and the drum diameter. In addition, the separation effect is also related to the separation temperature, processing capacity, outlet pressure. The higher the separation temperature, the less the processing capacity. The higher the outlet pressure, the better the separation effect.

For the vertical disc centrifuge, also called disc separator, there is a self-cleaning drum in it. The drum is used for liquid purification or solid collection. Due to the density difference between the solid and the liquid, under the action of the centrifugal force, the solid phase is separated from the liquid phase. The suspensions are fed into the drum from the inlet, and accelerated to be thrown into the disc groups. The disc groups are composed of many conical discs stacked one by one. The solid particles are thrown at the discs and fall into the solid collection zone, and discharged regularly. The purified liquid flows to the center of the drum, enters the centripetal pump chamber, and discharged out of the drum by the pressure of the centripetal pump.

4. Application of Disc Separator in Wine Production

4.1 Used for Clarification of Dry White Grape Juice Before Alcohol Fermentation

The clarification of dry white grape juice before alcohol fermentation can reduce the content of higher alcohols in wine, and improve the content of lipids, especially the content of six, eight and ten carbon fatty acid ethyl ester, so as to improve the quality of dry white wine. In the actual production process, the pressed dry white grape juice is usually placed in a low temperature decanting tank to reduce he temperature to 0-5 ℃. After settling for 1-2 days, the supernatants will be extracted to be clarified by the disc separator.

4.2 Clarification of Wine After Fermentation

After fermentation, the wine is still turbid, because there are some suspended substances in the wine, including pectins, pericarps, seeds, etc. Due to the release of CO2, these substances are still suspended in the wine. After settling, these substances will gradually settle at the bottom of the tank, and the purpose of barrel changing is to separate the wine from the other sediments. Then, the wine needs to be clarified again by the disc separator.