The impeller refers to both the rotor with the moving blades, the components of the impeller of the impeller, and the general name of the roulette and the rotating blades mounted thereon. The impeller can be classified according to shape and opening and closing conditions.
Impeller classification
The centrifugal pump impeller mainly has the following four forms, (a) closed type; (b) front half open type; (c) rear half open type; (d) open type
1—impeller; 2—rear cover; 3—wheel hub; 4—front cover; 5—impeller seal ring; 6—reinforced rib
Closed impeller
It consists of a blade and a front and rear cover. The closed impeller has high efficiency and is difficult to manufacture, and is most widely used in centrifugal pumps. It is suitable for conveying clean water without particles, such as clean water and solution.
Semi-open impeller
Generally, there are two kinds of structures: one is a front half-open type, which is composed of a rear cover plate and a blade. The impeller of this structure is low in efficiency, and a sealing ring with an adjustable gap is needed for improving efficiency; the other is a rear half-open type. It consists of a front cover plate and a blade. Since the same sealing ring as the closed impeller can be applied, the efficiency is basically the same as that of the closed impeller, and the blade has a sealing function (back blade or auxiliary impeller) in addition to the liquid. The semi-open impeller is suitable for conveying liquids containing suspended solids such as solid particles, fibers, and the like. The semi-open impeller is less difficult to manufacture, lower in cost, and more adaptable. It is gradually used in centrifugal pumps for refining and chemical industry, and is used to transport clean water and liquids with similar water.
Open impeller
Only the blade and blade ribs, the impeller without front and rear cover (the number of open impeller blades is 2-5 pieces less). The impeller has low efficiency and low application, and is mainly used for conveying liquid with high viscosity and slurry liquid.
The blades of the centrifugal pump impeller are generally curved blades. The blade has two kinds of cylindrical and twisted shapes. The application of the twisted blade can reduce the load of the blade, improve the suction performance of the centrifugal pump, and improve the anti-cavitation capability, but it is difficult to manufacture and has a high cost.
The centrifugal pump for refining and chemical engineering requires the impeller to be an integral impeller for casting or full weld welding. The welding impeller has been developed and is used in special centrifugal pumps for chemical industry made of poorly cast metal materials such as iron and its alloys. The geometric precision and surface finish of the welding impeller are better than the casting impeller, which is beneficial to improve the efficiency of the centrifugal pump.
