What is a Screw Pump?

Screw pumps are pumps that utilize the rotary motion of spiral open vanes to increase the potential energy of the liquid. Spiral pump belongs to low-pressure, dilute phase transportation equipment. It consists of a motor, coupling, bearing housing, screw shaft, support, check valve, mixing chamber, nozzle, and so on.

Powder from the discharge port into the screw conveyor pump, in the variable pitch screw extrusion and strong push, the powder uniformly into the mixing chamber, in the mixing chamber is equipped with nozzles in the lower part of the compressed air through the nozzle box sprayed into the mixing chamber.

Under the effect of jet and pressure difference, the powder will enter the conveying pipeline with suspended flow rapidly, and be transported to the receiving bin, the air is filtered by the air separator at the top of the bin and then discharged into the atmosphere, and the powder falls into the receiving bin under the effect of gravity to complete the powder conveying. Screw pumps are widely used in conveying water, wet sludge, and flocculant liquid in sewage treatment plants because of their variable conveying, strong self-priming ability, reversible, and ability to convey liquids containing solid particles.

The Types of Screw Pump

The screw pump is categorized by the number of screws.

• Single screw pump-pumps in which a single screw engages and rotates in an internally threaded groove in the pump body.
• Twin-screw pump-pumps by two screws engaged with each other to transport liquid.
• Three-screw pump-by more than one screw intermeshing pumps to transport liquid.

Single Screw Pump

Single screw pump belongs to the rotor type volumetric pump, which relies on the mutual meshing of screw and liner in the suction chamber and discharge chamber to produce volume changes to transport liquid. It is a kind of internal mesh closed screw pump, the main working parts by the double-ended spiral cavity of the liner (stator) and in the stator cavity and its engagement with the single-ended spiral screw (rotor) composition.

When the input shaft through the universal joint drives the rotor around the stator center for planetary rotation, stator-rotor vice is continuously engaged to form a sealing cavity, these sealing cavity volumes are unchanged for the uniform axial movement, the conveying medium from the suction end of the stator-rotor vice conveying to the end of the pressure out of the inhalation of the media into the airtight chamber of the media flow through the stator without being stirred and destroyed.

Its advantages are simple structure, easy maintenance, and cleaning, suitable for conveying high-viscosity media and media containing hard particles, such as sewage. However, the working principle of the progressive cavity pump determines its conveying capacity in a certain range of restrictions, so it is not suitable for large flow conveying.

Twin-screw Pump

Twin-screw pumps are formed by the main driven shaft of the mutual meshing of the screw sleeve and the pump body or liner between the formation of a sealed chamber with a constant volume, the medium with the rotation of the screw shaft was sent to the middle of the pump body, the two together, and ultimately sent to the exit of the pump, to achieve the purpose of the pump conveyance.

Compared with the single-screw pump, the twin-screw pump has a higher flow rate and pressure, suitable for conveying high-speed flow media, such as petroleum, chemical, metallurgical, and other industries. Twin-screw pumps have a complex structure, requiring high manufacturing processes and technology, while the cost is also relatively high.

Three-screw Pump

Triple-screw pumps are formed by relying on the pump body and screw, when the active screw rotates, driven with its meshing slave screw to rotate together, the suction chamber at one end of the screw meshing space volume gradually increases, the pressure decreases, its is through the three mutually helical axial line to achieve the transmission of fluids.

Triple-screw pumps in the stability of the transport medium and flow than the double screw pump higher, suitable for transporting high temperature, high viscosity, flammable and explosive media, such as heavy oil, asphalt, Hays, environmental protection, and other fields. However, relatively speaking, the three screw pumps work more noise, the length of the pump body is also longer, and the installation requires more space.

Summary

Screw pump selection should follow the principle of economic, reasonable, and reliable. If the design selection is not well thought out, it will bring trouble to future use, management, and maintenance, so choosing a reasonable and reliable screw pump according to the actual needs of production can ensure smooth production and reduce repair costs.