What type of pump is used for highly viscous fluid and Why?

When it comes to pumping highly viscous fluids — think heavy oils, sludges, syrups, or even molasses — the engineering challenges are considerable. The choice of pump technology becomes critical, and in most cases, positive displacement pumps, specifically gear pumps and screw pumps, emerge as the preferred choice. There are several reasons why these types of pumps are more appropriate for handling highly viscous fluids.

Firstly, positive displacement pumps move fluids in discrete, enclosed volumes, making it easier to handle thicker substances. In these pumps, fluid is caught in the cavities formed between the pump components, be it the interlocking gears in a gear pump or the helical rotors in a screw pump. This enclosed volume is then moved from the inlet to the outlet, ensuring a continuous and consistent flow. Because the volume is enclosed, the pump’s efficiency remains relatively constant irrespective of the fluid’s viscosity.

Secondly, gear and screw pumps are inherently self-priming, which means they can initiate pumping without requiring the fluid to be fed into the system, a significant advantage when dealing with viscous fluids that do not flow freely. Self-priming capability simplifies the design of the overall system and makes operation more straightforward.

Thirdly, the mechanical simplicity of positive displacement pumps, particularly gear pumps, allows them to be robust and relatively easy to maintain. This is a crucial factor in industrial applications where downtime can be costly. These pumps are designed to be sturdy, capable of handling the wear and tear associated with moving thick, sometimes abrasive, fluids.

Fourthly, these pumps allow for a wide range of flow control options. While the viscosity of the fluid may change due to temperature or other factors, positive displacement pumps can adapt to these changes more readily than other pump types. This makes them highly versatile and adaptable to varying operational conditions.

However, it’s worth mentioning the potential drawbacks. Positive displacement pumps, particularly when handling highly viscous fluids, may require more frequent maintenance to replace worn components. They may also be less energy-efficient than other types of pumps when used in applications they are not specifically designed for. Despite these limitations, their advantages make them the preferred choice for highly viscous fluid applications.

In summary, for pumping highly viscous fluids, gear pumps and screw pumps, types of positive displacement pumps, are often employed. They offer consistent flow rates irrespective of fluid viscosity, self-priming capabilities, robustness, and versatility, making them the go-to technology in industries such as food processing, petrochemicals, and waste management.