The impeller of a centrifugal pump transfers the energy of the prime mover through centrifugal force to the liquid in the pump, which increases the speed and pressure of the liquid, and causes the liquid discharged from the pump, and the liquid in the inlet pipeline is sucked into it.
Common materials for impeller are cast iron HT20~40, HT25~47, cast steel ZG15 and ZG25, cast copper ZGCuR, stainless steel 1Cr13, 2Cr13, 1Cr18Ni9Ti, and aluminum cast iron as well.
The impeller according to the structure can be divided into four forms: the first form, is composed of a front cover, a back cover, a blade and a hub, called closed impeller (figure a); second kinds of forms, composed of a back cover, a blade and a hub, called semi open impeller (figure b); third kinds of forms. Composed of blade and hub, called open impeller (Figure C); fourth, 7 by the two front cover, blade and hub, with two in two on both sides of the inlet, called double suction impeller (Figure D).
Semi open and fully open impeller are often used to transport liquids containing more impurities. Double suction impeller is usually used in large displacement occasions, which has good cavitation resistance and high efficiency.
Centrifugal pump impeller is mainly in the following 4 forms, closed, the first half of the open, the second half of the open, the open type of these four.
1, closed impeller is composed of blades and before and after the cover. The efficiency of the closed impeller is high and the manufacturing difficulty is great. It is used most in centrifugal pump. A clean liquid which is suitable for conveying clean water and less viscosity of the solution.
2, the semi open impeller: there are two kinds of structure for the first half open, composed of back cover and leaf structure, the impeller efficiency is low, in order to improve the efficiency to be matched with adjustable gap sealing ring for another half open, is composed of a front cover plate and the blade, as can be applied with closed impeller pump the sealing rings of the same efficiency? And closed impeller and blade are basically the same, in addition to conveying liquid, also has a sealing function of back blades or vice impeller. The semi open impeller is suitable for transporting liquid containing suspended solids, such as solid particles and fibers. Semi open impeller manufacturing is less difficult, cheaper and adaptable. In recent years, it has been applied more widely in centrifugal pumps for refining and chemical industry, and is used for transporting liquid with clear and near clean water.
3, open impeller: only blade and blade reinforcement, no front and rear cover of the impeller. The number of open impeller blades is less than 2-5 pieces. The pump impeller has low efficiency and less application. It is mainly used to transport the liquid with high viscosity and slurry.
The blade of the impeller of a centrifugal pump type pump is generally a rear curved blade. The blades are cylindrical and twisted. The twisted blades can reduce the load of the blades, and improve the suction performance of the centrifugal pump and improve the anti cavitation capability. But the manufacturing is difficult and the cost is high. Two The centrifugal pump used for the pump impeller refining chemical industry requires the impeller to be the whole pump impeller of the cast or the full weld. The impeller of the welding pump is developed in recent years. It is mostly used for metal materials with poor casting performance, such as iron and its alloys, and special centrifugal pumps used in chemical industry. The geometric precision and surface finish of the impeller of the welding pump are all better than the cast impeller, which is helpful to improve the efficiency of the centrifugal pump.
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