What is the difference between a screw pump and a centrifugal pump?

The centrifugal pump is a liquid conveying machine that rotates the impeller, transfers mechanical energy to the liquid, allows the liquid to obtain kinetic energy, and converts the kinetic energy into static pressure energy through the volute. The working principle is centrifugal action. The characteristic of centrifugal pump is that the working range is large, and the pressure head changes with the lift.

The working principle of a centrifugal pump is centrifugal motion. Centrifugation is actually a manifestation of the inertia of an object, such as water droplets on an umbrella. When the umbrella rotates slowly, the water droplets will rotate with the umbrella. This is because the friction between the umbrella and the water droplets acts as the centripetal force for the water droplets. caused by. But if the umbrella rotates faster, the friction force is not enough to make the water droplets move in a circular motion, then the water droplets will move away from the umbrella and move to the outer edge, just like pulling a rock with a rope to make a circular motion. If the speed is too fast, the rope will Disconnect, the stone will fly out, this is the so-called centrifugation.

When the centrifugal pump is working, the high-speed rotating impeller blades drive the liquid to rotate, and the liquid is thrown out, so as to achieve the purpose of conveying. Before the centrifugal pump works, the pump body and the water inlet pipe must be filled with liquid to form a vacuum state. When the impeller rotates rapidly, the blades cause the liquid to rotate quickly, and the rotating liquid flies away from the impeller under the action of centrifugal force. After the liquid is thrown out, the central part of the impeller forms a vacuum area, and the external liquid is pressed into the water inlet pipe through the pipe network under the action of atmospheric pressure. This cycle is endless, and continuous conveying can be achieved.

The screw pump is similar to the gear pump in many aspects. It uses the rotation of the screw to suck and discharge the liquid. The mutual meshing of the screws and the close cooperation between the screw and the inner wall of the liner will be between the suction port and the discharge port of the pump. Divided into one or more sealed spaces. With the rotation and meshing of the screw, these sealed spaces are continuously formed at the suction end of the pump, enclosing the liquid in the suction chamber, and continuously moving from the suction chamber to the discharge end along the axial direction of the screw, sealing the liquid enclosed in each space. The liquid is continuously discharged, just as a nut is continuously pushed forward when the thread rotates. This is the basic working principle of the screw pump.

The screw pump is suitable for conveying high-viscosity media, and can convey media with a viscosity ranging from 37000-200000 centipoise according to the size of the pump. For media containing particles or fibers, the particle diameter can be 30mm (not exceeding the rotor eccentricity). Fiber length can be 350mm (equivalent to 0.4 rotor pitch).Its content is generally up to 40% of the medium pit. If the solid in the medium is in the form of fine powder, the content can reach 60% or more and can also be transported. When the conveying pressure is required to be stable and the inherent structure of the medium is not damaged, it is ideal to use a screw pump for conveying. According to the number of screws, there are several types of single-screw pumps, twin-screw pumps and multi-screw pumps.

 

 

 


Post time: Sep-16-2022