What Is Screw Pump
A screw pump, occasionally referred to as a water screw, is an instance of positive displacement (PD) pump that transports liquids or solids along the screw axis using one or more screws. In the simplest possible form, material is moved along the screw’s spindle by a single screw rotating within a cylindrical chamber. Many low-tech applications, such irrigation systems and agricultural machinery used for transporting grain and other resources, still make use of this outdated design.
An array of multi-axis technologies, using carefully constructed screws spinning in opposite directions or sitting still within a container, are being made available by the creation of the screw pump. It is attainable to contour the cavity to create “locked-in” cavities for the material that is being supplied. A three-spindle screw pump is frequently employed in offshore and maritime applications to pump viscous fluid at high pressure. The pumped liquid in a closed chamber is pulled forward by three screws. The liquid that is pumped travels along the screw’s spindles as the screws rotate in opposite directions.
Viscous liquids having lubricating properties are shipped using screw pumps with three spindles. Many applications, such as fuel injection, oil burners, supercharging, hydraulic systems, fuel, lubrication, circulation, supply, and more, are suitable for them. Especially contrasted with centrifugal pumps, positive displacement pumps offer an assortment of advantages. Because there is no turbulence as the pumped substance moves axially, viscous liquids do not froth. Higher viscosity liquids can also be pumped without reducing flow rate. In addition, PD pumps are generally immune to changes in the pressure disparity in comparison with centrifugal pumps.
Screw pumps are versatile tools used for transporting viscous fluids with lubricating characteristics. They have various uses in industries like mining, manufacturing, gas, and oil. These pumps are suitable for high viscosity fluids like asphalt, oil, and multi-stage liquids. They are used in various systems like lubrication, hydraulic systems, multi-phase pumping, and heavy oil pipelines. The use of screw pumps allows for efficient transportation of viscous fluids, ensuring their safety and efficiency.
How Does Screw Pump Works?
Two counter-rotating screw rotors that rotate “towards each other” are used in screw pump activities. As a consequence, gas accumulates in the area between their rotors’ “screws.” This volume decreases as the nuts turn, squeezing the gas and forcing it in the opposite direction of the exhaust. In the first situation, the rotors have support at both ends by mechanical bearings. The rotors can be internally cooled and maintained at the high-pressure end by the cantilever design solution. Through a gear, a motor controls the two rotors.
The compression is oil-free because the gear and bearings are lubricated but maintained separate from the pumping mechanism (which is also referred to as the “vacuum generator”) by shaft seals or labyrinth seals. There is no mechanical wear since there is no contact between the rotors and the pump housing. Modern pumps are controlled by an electronic frequency converter and rotate less rapidly at pressure ranges that are near atmospheric pressure with the goal to reduce the installed electrical power. Some modifications, in order to preserve a constant velocity of rotation regardless of increased pressures, replace blow-off valves. Water is generally employed for cooling.
Screw pumps are a popular choice for various applications, including high-power applications like oil movement across tubes, small-scale projects like hydraulic systems, and multiple hydraulic and tube oil applications. There are numerous variants of screw pumps, such as PC pumps, progressive cavity pumps, and worm pumps. These pumps have rotors that resemble twisted round shafts, making them less related to the screw pump family.
Two-screw pumps, also known as double screw pumps, are commonly used in high-power applications, such as oil movement across tubes. Timing gears are typically used when combined with the motor to drive the next screw in the pumps. Three-screw pumps, also known as triple screw pumps, are used in small-scale projects like hydraulic systems. The pump’s remaining screws turn without the need for timing gears, using the motor to detect which screw needs to be turned.
Pumps with four screws, similar to two-screw pumps, have two screws traveling in opposite directions, capturing liquid in the suction port and sending it to both pumps. They have a timing mechanism to turn on the second rotor, similar to the double screw pump. Pumps with five screws, similar to triple screw pumps, have a single diving rotor that turns on the remaining screws. They are widely used for multiple hydraulic and tube oil applications.
The advantages of screw pumps include flexibility with various liquid types, pressures, flow rates, viscosities, steady flow rates, elevated volumetric effectiveness, manageable yield, minimal internal velocities, high tolerance to air or gases, silent and seamless functioning, extremely faint heartbeat, self-priming traits, and reduced mechanical vibration. However, disadvantages include carrying a lot and being heavy, vulnerable to fluid viscosity fluctuations, low mechanical and thermodynamic efficiencies, and high production costs for precise screw production.
