Although ultrafiltration technology has started late in China, it has developed very rapidly. With the continuous promotion of this technology and people's increasing awareness of it, the beverage production industry will certainly gain more benefits.
Ultrafiltration membrane equipment in industrial applications have flat, tubular, spiral plate-like and hollow fiber-like in several different forms. Most of the domestic applications are plate and tube, especially hollow fiber membranes (hollow fiber membranes) have also been widely used in water treatment.
Hollow fiber ultrafiltration membrane is the most mature and advanced form of ultrafiltration technology. This membrane is a thin film with a spatial three-dimensional geometry developed on the basis of a flat membrane, so that a unit volume of the membrane device does not rely on an extremely thin semipermeable membrane and has a large membrane permeability. The hollow fiber tube wall is covered with micropores, and the pore size is expressed in terms of the relative molecular mass of the retentate material, and the molecular weight can be several thousand to several hundred thousand. Due to the hollow-cylindrical configuration, the capacity per unit volume of membrane infiltration equipment is greatly increased. The raw water flows under pressure in the outside of the hollow fiber or in the inner cavity and constitutes an external pressure type and an internal pressure type, respectively. Ultrafiltration is a dynamic filtration process, and the retained substances can be eliminated with the concentration without blocking the membrane surface and can be continuously operated for a long period of time. It can be proved that in the ultrafiltration application, using a cylindrical bundle of a small-diameter hollow fiber membrane with a reasonable size, the amount of permeate generated would be equivalent to that obtained by a dozen square meters of ultra-thin flat membranes.
The hollow fiber is a slender membrane tube, and the inner wall is a membrane layer. The membrane layer is bonded to the sponge-like outer wall. The outer wall has coarse pores, and the inner layer performs ultrafiltration separation. The size of the hole in the inner membrane determines the size of the hindered substance in the tube. The hollow fibers have an inner diameter of about 200 μm, made of an inert non-ionic polymer, and have a unique anisotropic (skin) structure with a clearly high flow rate. Its characteristics are as follows: 1 The membrane area per unit volume of the device is large; 2 The membrane wall is thin, the liquid permeation speed is fast; 3 The hollow fiber has a certain pressure resistance performance due to its geometric configuration, so the strength is high.