The feasibility of fine powder classification with a cyclone separators is illustrated by a theoretical analysis of hydrodynamics. Adequate pre-dispersion and good pre-classification are important to improve the accuracy and efficiency of the classification of cyclone separators. The key words, cyclone separators micro-powder level 1 foreword, cyclone separators have long been used in many industries as air-solid separation devices. In recent years, there has been renewed interest in research. As separators, studies of structure, separation mechanisms and fluid analysis have entered a new phase, and many empirical formulas have been refined, guided by hydrodynamics, geometry and similar theories. The classification studies of recent years have shown that it is both possible and feasible to grade fine powders using cyclone separators. It is well known that the advantages of having a cyclone separation device in terms of motor parts, job stability, low cost, maintenance facilities, etc., would undoubtedly open up a new horizon for the development of graders and the application of cyclone separators if they could be used for the classification of fine powders. This paper is intended to start with the structural improvements of the cyclone separators and to describe the feasibility of analysing their use for fine powder classification. 2 a number of previous studies suggest that cyclone separators are less efficient in separating fine particles, making it difficult to effectively grade fine particles. The main reasons for this are: (1) that, at normal air flow speed (generally 20 m/s upper limit for entry flow speed), the centrifugal effect of the flow is weak enough to separate the fine particles from the current; (2) that, at excessive air flow speed, it is possible to reduce the efficiency of separation by having the rough particles that had been separated once again in the flow because of the impact of the bumping of the rough particles on the barrel wall; and (3) that, at some point in time, the geometric dimension of the cylinder will lead to an increase in the rate of increase in the flow of air within the exhaust tube if the flow is excessive, so that the particles that have fallen to the bottom cone of the wall are re-carried with the cyclone. However, the author believes that the classification of fine particles should take into account their specificity. First of all, micro-scale particles are much smaller in mass than tens of micrometres of coarse particles, so that they have a much smaller centrifugal power at the same current speed, and, accordingly, centrifugal deposition is hundreds or thousands of times smaller, even when the flow is high. More nuanced particles are much more walled than rough particles, which make it very unlikely that they will collide back when they sink into the barrel. Secondly, according to the normal cyclone separator's current field analysis, there is a negative velocity gradient in the direction of the current, as the radius of the location of the fluid microgroup increases. The effect of this velocity gradient (repulsive resistance) may be insignificant for the repulsive of the thick particles, but it cannot be ignored for the fine particles. Thirdly, the problem with the rate of uptight air flow in the exhaust pipe to the particles on the wall of the cone can be solved by increasing the inner diameter. The formulas and those derived decades ago by rosin, rammler and intelmann and fuchs, de-vies and others demonstrate that appropriately reducing the diameter of the cyclone, increasing the speed of the imported air flow and extending the centrifugal motion of the particles within the drums can reduce the size of the class particle. A particle with a diameter of dp when moving around a radius of r's centrifugal velocity ut's circle fd's centrifugal strength f = (π6) d 3 p old p u 2 t/r(1) f d = 3 mm d p dr / dt(2)14 is the feasibility of fine powder classification with a cyclone separator doi: 10. 16759 /j. Cnki . Assn. 1007-7251. 199501. 010. 003
