Homogenization technology in the food, chemical, pharmaceutical and other industries has become the key to improving product quality. At present, the traditional homogenizing equipment used in the domestic food industry is mostly high-pressure homogenizer, colloid mill, sand mill and roller mill. In recent years, new high-shear homogenizer equipment has appeared. As for these homogeneity The application of equipment in various industries has not been systematically studied. In this regard, the author conducted a comparative analysis of the homogenization principle, the process flow of different materials and experimental data for the high-pressure homogenizer and high-shear homogenizer currently used. 1 Homogeneity mechanism analysis The direct cause of fragmentation of dispersed phase particles or droplets in a liquid material dispersion is the effect of shear and pressure. The specific hydrodynamic effects that cause shear and pressure are mainly laminar, turbulent and cavitation effects. The laminar flow effect causes shearing and elongation of the dispersed phase particles or droplets; the turbulence effect causes random deformation of the dispersed phase particles or droplets under pressure fluctuation; the cavitation effect is to cause the formed small bubbles to instantaneously break to generate shock waves. And caused a strong agitation. High shear homogenization mechanism At present, the line speed of the shear homogenizer commonly used in China is usually 10 to 25 m/s. Practice has proved that its homogenization effect is not ideal. The high shear homogenizer refers to a shear homogenizer with a line speed of 30-40 m/s. The main working parts are 1 or more stages of stator and rotor. The rotor has several layers of ring gears. Working principle: the rotor with blades rotates at high speed to produce a strong separation The heart field forms a strong negative pressure zone in the center of the rotor. The liquid (liquid-liquid or liquid-solid mixture) is sucked from the center of the stator. Under the action of centrifugal force, the material spreads from the center to the periphery and spreads around. During the process, the material is first agitated by the blades and at the end faces of the blades and the stator The narrow gap inside the ring gear is sheared and then enters the narrow gap between the inner ring and the fixed tooth. Under the action of mechanical force and hydrodynamic effect, it produces large shear, friction, impact and material. The collision and friction of the dispersed phase cause the dispersed phase particles or droplets to break. As the linear speed of the rotating tooth is gradually increased from the inner ring to the outer ring, the pulverizing environment is continuously improved, and the material is crushed more and more by the action of shearing, friction, impact and collision during the outer ring movement. The finer it is, the more homogeneous the emulsification is achieved. At the same time, in the negative pressure region of the rotor center, when the pressure is lower than the saturated vapor pressure (or air separation pressure) of the liquid, a large number of bubbles are generated, and the bubbles are crushed with the liquid flow to the stator ring gear or collapse with the pressure rise. . At the moment of collapse, a microjet is formed at the center of the bubble. The jet velocity can reach 100 m/s or even 300 m/s. The impact force generated can be estimated by the water hammer pressure formula, ie P = ÏCaC, where Ï is Liquid density; Ca is the speed of sound in the liquid; C is the speed of the microjet. Let C be 100 m / s, the resulting pulse pressure is close to 200M Pa, which is the cavitation effect. Strong pressure waves can cause soft, semi-soft particles to be comminuted, or hard agglomerated fine particles to be dispersed. It can be seen from the analysis that the mechanism of homogenization of materials in the stator and rotor cavity is more complicated. The author believes that shearing plays a leading role, followed by cavitation. High pressure homogenization mechanism High-pressure homogenization is the use of high pressure to cause the liquid material to flow through a narrow gap at a high speed, and the strong shear force, the liquid material is impacted on the metal ring to generate a strong impact force, and the cavity generated by the sudden drop and sudden rise of the static pressure. The combination of explosive force and the like, the process of processing a relatively coarse emulsion or suspension into a very fine stable emulsion or suspension. When the homogeneous material passes through the adjustable gap h (usually 011 mm) between the valve seat and the valve stem, the flow rate is accelerated to 200-300 m/s in an instant, resulting in a huge pressure drop when the pressure is reduced. At the saturated vapor pressure (or air separation pressure) of the liquid at the working temperature, the liquid begins to "boiling" and rapidly "vaporizes", generating a large amount of bubbles inside. The liquid containing a large amount of micro-bubbles flows out toward the slit outlet, the flow rate is gradually reduced, and the pressure is increased. When the pressure is increased to a certain value, the bubble in the liquid suddenly bursts and re-condenses, and the bubble is generated and collapsed instantaneously. A cavitation phenomenon is formed. The phenomenon of cavitation is like a myriad of miniature bombs. The intense release of energy produces strong high-frequency vibrations. At the same time, with the strong shear force generated by strong turbulence, the soft and semi-soft particles in the liquid are in the cavity and turbulent. The shear force is combined to be pulverized into particles, wherein the effect of the cavitation effect is considered to be large. The pulverized particles are then impacted at high speed onto the impact ring and further pulverized and dispersed. Comparison and analysis According to the above analysis, the high-shear homogenizer is mainly due to the high shearing action caused by the relatively high-speed motion between the stator and rotor, and the material particles are dispersed, refined and homogenized with strong cavitation. And the high pressure homogenizer is mainly strong by high pressure fluid Xmas Gummy Candy,Christmas Gummies,Christmas Gummy Candy,Fruity Christmas Candy Montreal Shantou Food Co., Ltd , https://www.montrealsnack.com