Screw pump is divided into single screw pump, twin screw pump, three screw pump. This article describes in detail their structure, characteristics, performance parameters, the difference between the four aspects of the application, as well as their advantages and disadvantages. Such as single-screw pump structure for the single-headed male screw rotors in a special double-headed female screw rotors eccentric (stator is soft), can swing back and forth along the pump center line with the stator always maintain engagement, twin screw pump structure There are two screw shafts of the same size, one is a driving shaft, one is a driven shaft, and a synchronous rotation is achieved through gear transmission. Single screw pump structure: The single-headed male screw rotor rotates eccentrically within a special double-headed female screw stator (the stator is soft), swings back and forth along the pump centerline, and remains engaged with the stator. Features: 1, can transport liquid containing solid particles 2, almost any viscosity of the fluid, especially for high viscosity and non-Newtonian fluid 3, the working temperature is limited by the stator material Performance parameters: Flow up to 150m3 / h, pressure up to 20MPa Application: For molasses, pulp, starch paste, chocolate pulp, paint, tar, paraffin, grease, mud, clay, clay and so on. Twin screw pump structure: There are two the same size of the screw shaft, a drive shaft, a driven shaft, through the gear drive to achieve synchronous rotation. Features: 1, Screw and pump body, as well as between the screw to maintain 0.05 ~ 0.15mm gap, wear small, long life 2, stuffing box only by the suction pressure less leakage 3, compared with the three screw pump, the impurity is not sensitive Performance parameters: The pressure is generally about 1.4MPa, viscous liquid maximum of 7 MPa, the viscosity of the liquid up to 3 MPa, the flow is generally 6 ~ 600m3 / h, the maximum 1600 m3 / h Liquid viscosity can not exceed 1500mm2 / s Application: For lubricating oil, grease, crude oil, asphalt, fuel oil and other high viscosity oil. Three screw pump Structure: It consists of an active screw rod and two driven screw rods engaged with it. Features: 1, the active screw directly driven driven screw, without gear, the structure is simple 2, the pump itself as a screw bearing, no need to install radial bearings 3, the screw does not withstand the bending load, can be made very long, so high pressure can be obtained 4, should not be transported with more than 600μm solid impurities in the liquid 5, high-speed operation, is a small high-flow pump, high volumetric efficiency 6, stuffing box connected only with suction pressure, less leakage Performance parameters: Pressure up to 70 MPa, flow up to 2000m3 / h. Suitable viscosity of 5 ~ 250 mm2 / s medium. Application: Suitable for transporting lubricating oil, heavy oil, light oil and crude oil. Can also be used for glycerol and viscose and other highly viscous liquid delivery.