Screw Pump
Screw pumps are a versatile and efficient pumping solution used for fluid transfer in a wide range of industries. These pumps are known for their reliability, low pulsation flow, and ability to handle a wide range of viscosity and solids-laden fluids. We will explore the key features, benefits and applications of screw pumps, highlighting why they are an important tool for industrial fluid handling.
What is a screw pump?
A screw pump is a type of positive displacement pump that uses one or more helical screws to move fluids along the pump’s internal cavity. The screw(s) rotate inside a cylindrical casing, pushing the fluid from the intake (suction) to the discharge (outlet) in a continuous and smooth motion. This pump is widely known for its ability to handle viscous liquids, slurry, and liquids containing solid particles with minimal pulsation.
Working Principle of Screw Pumps
Screw pumps operate based on the positive displacement principle, where a fixed volume of fluid is moved with each rotation of the screw(s). The primary mechanism of a screw pump is the movement of one or more helical screws inside a cylindrical casing, which pushes the fluid from the suction side to the discharge side.
Components of Screw Pumps
- Screw
- Rotor
- Seals
- Bearing
1. Screw
The screw in a progressive cavity pump plays a vital role in its operation. In a twin-screw, low-pitch screw pump, it consists of two closely meshing screws with tight clearance, mounted on two parallel shafts. One screw has a right-hand thread and the other a left-hand thread. One of the shafts is the drive shaft, which drives the other shaft through a set of herringbone timing gears. The purpose of these gears is to maintain the clearance between the screws as they rotate and to provide smoother and quieter operation.
2. Rotor
Rotor is the core component of a screw pump, usually in the shape of a helix, responsible for generating fluid propulsion through rotation. The movement of the rotor is key to the pump’s operating process.
3. Seals
The seal is located between the rotor and the pump shaft and is used to prevent liquid leakage. It ensures that the liquid in the pump is hermetically sealed and reduces internal wear.
4. Bearing
Bearings support the pump shaft, ensuring smooth rotation of the shaft and reducing friction and wear, extending the life of the pump.
Screw Pump Applications
- Oil & Gas
- Chemical Industry
- Food & Beverage
- Pharmaceutical Industry
- Wastewater Treatment
Types of Screw Pumps
Single Screw Pumps
Working principle: Single Screw Pumps use a single helical rotor to propel liquid flow through the relative motion between the rotor and the stator in the pump body. The liquid is gradually pushed through the chamber of the screw to form a steady flow.
Features:
o Suitable for low flow rates and low to medium pressure applications.
o Has a smooth flow output.
o Can handle high viscosity and fluids containing solid particles.
Applications: Commonly used for transferring oils, chemicals, sludge and petroleum products.
Twin Screw Pumps
Working principle: Twin Screw Pump consists of two screw rotors that engage with each other. The two rotors rotate against each other, generating negative pressure to draw the liquid in and push the liquid to flow.
Features
o Provides higher flow rates and pressures than single screw pumps.
o Smooth operation, stable flow rate and virtually no pulsation.
o Suitable for high flow rate delivery and precise fluid control.
Applications: Widely used in oil and gas, chemical industry, food processing, seawater desalination, etc. Especially suitable for handling high viscosity fluids or liquids containing small particles.
Triple Screw Pump
Working Principle: Triple screw pump consists of three helical rotors, two of which rotate in mutual engagement with each other, while the third rotor is used to maintain clearance and enhance stability. The three rotors work together to ensure liquid flow.
Features:
o Higher pressure and flow output capability.
o Suitable for high pressure, high viscosity liquids.
o Due to the three rotors meshing with each other, the pump runs very smoothly with low vibration and noise.
Applications: Widely used in the fields of oil transportation, liquid transportation and pressure lifting, especially suitable for oil fields, chemical industries, lubricating oil, and other fields.
Progressive Cavity Pump
Working Principle: The Progressive Cavity Pump usually consists of a spiral rotor and a fixed inner cavity (sleeve). The spiral rotor rotates inside the sleeve, pushing the liquid along the path of the spiral.
Features:
o Suitable for high-viscosity liquids and fluids containing solid particles.
o Provides a stable flow rate at low operating speeds and is suitable for precise flow control.
Highly efficient suction capability, capable of handling mixtures of gases and liquids.
Advantages and Disadvantages of Screw Pumps
Advantages:
- Smooth flow: Provides steady, pulsation-free fluid transfer, ideal for sensitive applications.
- Handles high-viscosity fluids: Perfect for thick liquids like oils, syrups, and slurries.
- Self-priming: Can operate without manual priming, suitable for automatic systems.
- Can handle solids: Works well with fluids containing solid particles or abrasives.
- Durable: Long service life with minimal maintenance needs.
Disadvantages:
- Higher initial cost: More expensive than other pumps, like centrifugal pumps.
- Less efficient at high flow: Efficiency drops at very high flow rates.
- Wear on components: Abrasive particles can wear out internal parts faster.
- Maintenance needed: Seals and rotors require regular maintenance.
- Limited suction head: Can’t handle very deep suction well.
- Noise and vibration: Can be noisy and generate vibrations, especially at high speeds.
Summary
Inscrew pumps are a dependable and efficient choice for industries requiring consistent, smooth, and continuous fluid transfer. Whether it’s for handling viscous liquids, slurry, or simple water transfer, their robust design and versatility ensure optimal performance across a variety of environments.
AOBl pumps are well known in the industry for their high efficiency, reliability and durability. We always insist on customer-oriented and provide the best quality products and services for our customers. If you are interested in our products, please feel free to contact us and we will customize a professional water treatment solution for you.