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Chinese Library Classification Number: TS211.3 Document Code: A Article Number: 1005–1295(2006) 05–0048–02 At present, the soy product industry in China makes extensive use of centrifugal separators in production to separate soy milk from soy dregs. However, there are many different brands and models of such machines, most of which have low efficiency and high power consumption. To this end, improving its work efficiency and standardizing standards is a topic of research. 1 Principle and Application of Centrifugal Slurry Separators. A centrifuge is a machine that utilizes inertial centrifugal force for the centrifugal separation of solid-liquid and liquid-liquid phases. The main component of a centrifuge is the drum (sieve barrel) mounted on a vertical or horizontal axis, with small holes in its walls. The slurry is fed into the drum and rotates with it; separation is achieved under the action of inertial force, a process known as centrifugal filtration. The separation factor is the main indicator used to represent the separation performance of a centrifuge. It is defined as the ratio of the centrifugal force acting on a material to its weight, and it is also equal to the ratio of the centrifugal acceleration to the gravitational acceleration. That is, KC = Rω²/g, where KC is the separation factor ； ω—Rotational angular velocity of the drum ； R—drum radius ； g—acceleration due to gravity ； 2. Analysis of the structure and operation of the centrifugal slurry separator. This machine is composed of components such as a feed pipe, a screening tank, a nylon filter mesh, a main shaft, bearing housings, and a frame. The soybean milk paste entering through the feed port is stirred by the distributor and evenly sprayed onto the rapidly rotating inner wall filter screen. Under the effect of centrifugal force, the slurry is quickly flung out through the pores in the filter cake on the wall of the sieve barrel; after gathering in the lower housing, it flows out through the discharge port. Under the combined effect of its own gravity and centrifugal force, the soybean dregs slide continuously along the inner wall of the screening barrel toward the opening of the barrel, and then flow out through the discharge port, thereby achieving the separation of the pulp from the dregs. 3 Main factors affecting separation efficiency and design 1. Separation factor Kc ； 2. Concentration, viscosity, and particle size of soybean paste ； 3. Size of the mesh holes ； 4. Geometric shape, length, and taper of the screen ； To improve the separation efficiency from a design perspective, four aspects need to be considered. The separation factor is one of these aspects, but it is merely a range value; usually, several empirical parameters are employed. Even if the rotation speed of the screening barrel is increased significantly or its diameter is enlarged, it is still subject to limitations imposed by the strength of the material. Therefore, we started by studying the taper of the screening barrel in order to improve the screening efficiency. During the screening process, as soon as the soybean paste enters the rapidly rotating screening drum, under the action of centrifugal force and friction with the drum walls, a dense layer of soybean residue is immediately formed on the wall of the drum; this layer rotates at the same speed as the drum. We call this layer the retention layer. The soybean paste that enters the drum afterward can only slide along the inner surface of this retention layer in order to flow out of the drum, as the friction between the particles is less than the friction between the soybean paste and the drum walls. The retention layer serves both to filter out the soy milk and to create resistance to its flow out. Therefore, developing an appropriate retention layer is key to improving the efficiency of screening. 1 – Feed funnel 2 – Setting screw 3 – Front baffle 4 – Slurry separation partition 5 – Feed pipe 6 – Upper cover 7 – Slurry separator 8 – Main shaft and nozzle 9 – Bearing seat 10 – Lower cover 11 – Screening barrel 12 – Nylon filter screen and fixing clamp 13 – Slurry striking pipe 14 – Frame 15 – Connecting screw 16 – Foot screw 17 – Electric motor 18 – Motor fixing inclined plate 19 – Triangular belt. Since mathematical models based on theoretical calculations are not yet fully developed, we conducted numerous experiments and statistical analyses; as a result, we found that there is a close relationship between the angle of the screening barrel and the thickness of the slurry retention layer. The greater the cone angle, the thinner the retention layer, and the faster the slurry is discharged. When the cone angle is 20°, the thickness of the retention layer is approximately 4 millimeters, at which point the slurry discharge rate is highest. The statistical analysis data below is sufficient to illustrate this point. See the relevant illustration. Actual use has proven that the design is successful and practical, holding certain value for wider adoption. References: [1] Hu Jiqiang. Food Engineering Technology Equipment [M]. Beijing: Science Press, 2004. [2] Wang Hai. Principles of Food Engineering [M]. Beijing: Machinery Press, 1995. [3] Xu Hao. Mechanical Design Handbook [M]. Beijing: Machinery Press, 1991