In chemical production, material transportation is a fundamental yet critical process. Twin-screw chemical pumps are widely used for conveying various liquid media due to their simple structure and stable operation. However, in practical applications, it has been observed that pump performance can vary with changes in the transported materials. Among these factors, viscosity plays a significant role.
Viscosity refers to a fluid’s resistance to flow. For example, water flows easily and has low viscosity, while substances like lubricating oil or asphalt are much thicker and have higher viscosity.
For twin-screw pumps, changes in viscosity directly affect suction capability, efficiency, energy consumption, and even service life. If the viscosity is too high, the pump may struggle to draw in the fluid; if it's too low, internal leakage may occur, reducing efficiency. Therefore, choosing the right pump setup based on the material’s viscosity is essential for optimal performance.
Twin-screw pumps are popular in the chemical industry due to several key advantages:
Their main strength lies in handling medium-to-high viscosity fluids, such as crude oil, resins, and syrups.
Although twin-screw pumps perform well with medium-to-high viscosity media, adjustments should be made depending on the specific viscosity level:
Low viscosity (<50 cSt): Light-duty models are recommended for liquids like gasoline or solvents, with attention to sealing design to prevent leakage.
Medium viscosity (50–1000 cSt): Standard twin-screw pumps work efficiently in this range.
High viscosity (>1000 cSt): Heavy-duty models with wider screw profiles and heating jackets are preferred for heavy oils, asphalt, and similar media.
Avoid blindly selecting large or high-speed pumps. Select the appropriate model based on the actual viscosity of the medium being transported. Choosing incorrectly can lead to poor performance and frequent failures.
Higher speed does not always mean better performance. In fact, excessive speed can increase wear and energy consumption when dealing with high-viscosity media. A reasonable speed adjustment according to viscosity helps save energy and prolong equipment life.
Some high-viscosity liquids are difficult to move at room temperature. Using heating methods—such as steam or electric heating jackets—can improve fluidity and make pumping easier.
For corrosive or high-temperature/high-viscosity media, it’s important to choose the right pump materials and sealing types. Corrosion-resistant options like stainless steel or duplex steel, combined with mechanical or packing seals, help ensure long-term reliability.
A petrochemical company needed to transport heavy fuel oil with a viscosity of 8000 cSt. Initially, they used a centrifugal pump but experienced frequent suction failure, unstable pressure, and high energy consumption.
After switching to a heavy-duty twin-screw pump equipped with a heating jacket and a variable frequency drive for speed control, they successfully resolved the transportation issues. Energy consumption dropped by more than 15%, and maintenance frequency was significantly reduced.
This case clearly shows: the right pump combined with proper viscosity adaptation leads to improved efficiency and reduced downtime.
Viscosity adaptation may not be a complex engineering challenge, but it plays a crucial role in pump performance. From selection to operation and maintenance, considering the viscosity characteristics of the transported medium is essential.
If you're facing issues such as low transfer efficiency or high equipment wear, start by reviewing your viscosity adaptation strategy.
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