Centrifugal pump is mainly composed of impeller, shaft, pump shell, shaft seal and sealing ring. Structure plan of centrifugal pump (see figure).

(1) there are two types of pump shell: axial section and radial section. Most single-stage pump shells are volute, and the multi-stage pump radial split shells are generally circular or circular.

Generally, the inner cavity of the volute pump shell is a spiral channel for collecting the liquid thrown from the impeller and leading the diffusion tube to the pump outlet. The pump housing bears all the working pressure and the heat load of the liquid.

(2) the impeller is a working component, and the pump does work on the liquid through the impeller. There are three types of impeller: closed, open and semi-open. The closed impeller consists of a blade, a front cover and a back cover. The semi-open impeller consists of a blade and a rear cover plate. An open impeller has only blades and no front cover. Closed impeller efficiency is high, open impeller efficiency is low.

(3) sealing ring seal ring is also called mouth ring. The function of the sealing ring is to prevent the internal and external leakage of the pump. The sealing ring made of wear-resistant materials is mounted on the front and rear cover of the impeller and the pump shell, which can be replaced after wear.

(4) the impeller is fixed at one end of shaft and bearing pump shaft, and the coupling is installed at one end. According to the size of the pump, the bearing can choose rolling bearing and sliding bearing.

(5) shaft seal shaft seal generally includes mechanical seal and packing seal. General pumps are designed to fill both the stuffing and mechanical seal.

Working principle of centrifugal pump centrifugal pump commonly before the start of the pump shell filled with liquid, when the prime the pump shaft and the impeller rotates, the liquid on the one hand, with the impeller do circular motion, on the one hand, under the action of centrifugal force, the impeller center to the peripheral thrown, liquid can can get the pressure from the impeller and speed. When the liquid flows through the volute to the outlet, part of the velocity can be converted into static pressure energy. When the liquid is ejected from the impeller, the central part of the impeller creates a low pressure zone, which is different from the pressure on the suction surface, so the liquid is continuously inhaled and discharged with certain pressure.

Centrifugal pump has many advantages, such as wide range of performance, uniform flow, simple structure, reliable operation and convenient maintenance. Therefore, centrifugal pump is widely used in industrial production. In addition to the small flow or high-pressure measurement often used reciprocating pump, the liquid gas often used vortex pump and the positive displacement pump, high viscosity rotor pump is commonly used medium, the rest of the occasion, most of the use of centrifugal pump. According to statistics, in chemical production (including petrochemical) equipment, centrifugal pumps account for 70 to 80 percent of the total volume of pumps.