Disc Stack Centrifuge for Clarification and Concentration of Plant Extract

Plant extraction is a common process to obtain active ingredients from herbs, fruits and botanical raw materials. After hot water or ethanol extraction, the feed liquid is mixed with tiny plant fiber, cell debris and sticky colloidal substances. If these impurities are not removed effectively, they will cause blockage of filter cloth or membrane pores, increase cleaning frequency and shorten the service life of downstream separation modules. Traditional plate-and-frame filter press can remove solid residues, but it has obvious defects: long batch operation cycle, labor-intensive cake discharging, high loss of target liquid in filter cake, and the filtrate still contains submicron particles which cannot be completely removed.

Disc stack centrifuge uses a set of closely stacked conical discs inside the bowl. When the bowl rotates at high speed, the density difference between solid phase and liquid phase generates powerful centrifugal force. Fine solid particles quickly settle on the inner wall of the bowl, while the clarified liquid flows out from the light phase outlet. According to the solid content of feed liquid, the machine can adopt automatic slag discharge at fixed intervals or manual slag discharge mode. For plant extract projects, the centrifuge is usually arranged as the front pre-clarification unit before membrane filtration.

A typical combined process is: leaching tank → coarse filter → feed tank → disc stack centrifuge → intermediate tank → membrane concentration system. The centrifuge removes most of the coarse and fine slag first, greatly lowering the solid load entering the membrane module. This matching mode effectively reduces membrane fouling frequency, stabilizes membrane flux and cuts the consumption of cleaning chemicals. Operators can adjust feeding flow rate, bowl rotating speed and slag discharge interval according to raw material types and seasonal changes of plant materials.

This equipment has prominent advantages in botanical processing. The separation speed is fast, and continuous feeding and discharging can be realized. The clarified liquid has better transparency, and the loss of active liquid is much lower than filter press. The whole unit is designed with sanitary grade structure, easy to clean and sterilize, which meets the hygienic requirements of food and health product raw material production. It occupies a small floor area and can be integrated into an automatic extraction line together with pumps and control cabinet.

At the same time, proper operation limits must be noticed. If the feed liquid has extremely high viscosity or high oil content, the separation effect will decline. In this case, temperature adjustment or dilution pre-treatment is required. Too high feeding flow will shorten the settling time of particles and lead to turbid outlet liquid. Operators need to test the material first to confirm the suitable parameters. Regular inspection of seals, bearings and hydraulic system is necessary to keep stable long-time running.

As the market puts forward higher requirements on the clarity and shelf life of plant extracts, the combination of disc stack centrifuge and membrane separation becomes a mainstream process solution. The centrifuge undertakes the heavy load of solid removal, while the membrane system completes fine purification and concentration. This matched process helps manufacturers improve product yield, reduce auxiliary material cost and obtain stable and high-quality botanical raw liquid.