What is a scroll pump?

What is a scroll pump? What are the types and structural characteristics?

The impeller of the scroll pump is a disc of equal thickness, and there are many small radial blades on both sides of its outer edge. There is an annular flow passage with equal cross section on the pump shell corresponding to the blade. The whole flow passage is divided into suction and drainage by a tongue separator, which are connected with the suction and drainage pipelines of the pump respectively. When the liquid in the pump rotates with the impeller, it produces a certain centrifugal force, throws it outward into the annular flow passage in the pump shell, and is forced to return under the restriction of the flow passage shape, and re-enters the other blade passage behind from the blade root. Therefore, the liquid motion trace between the blade and the annular channel is a forward spiral for the stationary pump case, and a backward spiral for the rotating impeller. Scroll pump are named for the vortical motion of liquids. The liquid can enter the blades for energy several times continuously until it is finally discharged from the outlet. Scroll pump work a little like multistage centrifugal pumps, but they do not have energy conversion devices like volutes or guide vanes of centrifugal pumps. Scroll pump transfer energy to liquid mainly by means of continuous work for many times, so they can produce higher pressure. In the process of energy transfer, due to multiple impacts of liquid, the energy loss is large and the efficiency of the pump is low, generally 20-50%. Scroll pump are only suitable for situations requiring small flow (1-40 m 3/h) and high lift (up to 250 m), such as fire pumps, gasoline pumps on aircraft refueling trucks, small boiler feed pumps, etc.

Scroll pump can transport highly volatile and gaseous liquids, but they are not used to transport thicker liquids with viscosity greater than 7 Pa. seconds and unclean liquids with solid particles. Scroll pump features small flow, high lift, self-priming function, can be used to transport viscous less than 5 degrees E solid particles and its similar to water liquids. Such as gasoline, kerosene, alcohol, etc., can be used for small steam boiler water supply, chemical industry, pharmaceutical, high-rise water supply and other purposes. Overflow parts and stainless steel and other materials can be used to transport acid, alkali corrosive liquids. The temperature of the conveying medium is – 20 ~ + 80 degrees. From the structure, it can be divided into single-stage, double-stage, multi-stage, direct connection form and so on.

Scroll pump is a kind of vane pump. It first appeared in 1920. It was manufactured by German Siemens and Hensch Company. The important layout of the scroll pump includes impeller, pump body, pump cover and annular flow passage composed of them. The transport medium enters the runner from the suction pipe, and the rotating impeller obtains energy, which is transported to the extrusion pipe to complete the process of the pump. The working principle, layout and characteristic curve of the scroll pump are different from those of the centrifugal pump, the axial flow pump and the mixed flow pump. It is a kind of pump with small flow rate and high head, and its specific speed is usually less than 40. The minimum flow rate of the scroll pump can be 0.05L/s or less, and the large flow rate can reach 12L/s, which can replace the centrifugal pump in some places. When the specific speed of Ns is over 40, it is usually less used because of its obedience far lower than that of centrifugal pumps.

Scroll pump of Classification and Characteristics

Scroll pump can be divided into open type and closed type according to impeller type. Now there are impellers between open type and closed type impellers. Closed impeller blade is short, which is formed by milling grooves on the outer edge of impeller disc. The inner radius of impeller is the inner radius of flow passage. The liquid is transported directly from suction pipeline to flow passage. The inner radius of open impeller blade is less than the inner radius of flow passage. The liquid enters the impeller from suction tube, and the upside-down blade falls behind the flow passage. Long.

The impeller type is related to cavitation, self-suction and vapor-liquid mixing. According to the relative position of the runner and the extrusion port, it can be divided into open runner scroll pump, centripetal runner scroll pump and closed runner scroll pump. According to the relative position of flow passage and impeller, it can be divided into peripheral flow passage scroll pump, open peripheral side flow passage scroll pump and closed edge flow passage scroll pump.

Scroll Pump of Characteristics

Although the scroll pump belongs to the field of vane pump, its course, layout and shape of characteristic curve are quite different from those of centrifugal pump and other typical pumps. Because of the differences in the expression of the principle of the scroll pump by the quintessence of different countries. In the course of the operation of the scroll pump, because of the rotation of the impeller, the liquid in the impeller and in the passage has circumferential biased movement, so centrifugal force occurs. The circumferential velocity of the liquid in the impeller is larger than that of the liquid in the passage, that is, the centrifugal force of the liquid in the impeller is larger, so the axial and radial vortices are formed. Name.