Introduction to Eductor nozzles
Eductor nozzles, are an indispensable component in many industrial applications that require mixing, have issues with sedimentation and beyond. They operate on the Venturi principle, utilizing the pressure differential to create a suction effect that draws in and mixes surrounding fluids. This mechanism makes them highly effective for mixing, agitating, and circulating liquids within tanks, ensuring uniformity and preventing sedimentation. Their ability to move large volumes of fluid with minimal energy input makes them a cost-effective solution.
Why Eductor nozzles are used
Eductor nozzles are primarily used to maintain homogeneity in liquid tanks. They are particularly beneficial in applications where sedimentation or separation of liquids is undesirable. By continuously circulating the liquid, eductor nozzles ensure that the contents of the tank remain well-mixed, preventing solids from settling at the bottom. This is crucial in industries such as chemical processing, water treatment, and food and beverage production, where consistent fluid properties are essential for product quality and process efficiency.
Key considerations for using Eductor nozzles
Mathematics Behind Eductor Nozzles
Eductor nozzles move approximately five times the volume of the pumped fluid due to the suction effect created by the pressure differential through the shroud of the nozzle. The flow rate through the eductor is proportional to the pressure drop across the nozzle. Therefore, consulting flow rate vs. pressure charts is necessary to determine the appropriate size and number of eductors required for a given application.
For example, if an eductor is designed to ‘turn’ 1/5th of the tank’s fluid volume per hour, and the tank holds 1000 litres, the eductor should move 200 litres per hour. Given the 5x multiplier, the actual pumped fluid would be 40 litres per hour. This relationship is crucial for ensuring that the eductor system is neither underpowered nor overpowered for the application, which could be adverse to the desired goal.
Sizing Eductors
The sizing of eductors depends on the desired turnover rate, which varies by application:
For instance, in a blending application requiring 50 turns per hour in a 2000-liter tank, the eductor system must move 100,000 litres per hour. Given the 5x multiplier, the actual pumped fluid would be 20,000 litres per hour. This ensures that the fluid is thoroughly mixed and that any solids remain suspended.
Positioning Eductors
Proper positioning of eductors is critical for effective mixing. Eductors produce a plume of moving fluid with a length of 4.3 meters per 1 bar of pressure drop and a spray angle of around 12 degrees. They should be positioned to cover as much of the tank as possible, ideally hitting the opposite wall to maximize fluid movement and minimize blind spots. For applications requiring no sedimentation, eductors can be angled downwards to sweep the tank floor, with the plume reach halved to 2.15 meters per bar.
In a large tank, multiple eductors may be necessary to ensure even coverage. For example, in a 10-meter diameter tank, positioning eductors around the perimeter and angling them to create overlapping plumes can ensure thorough mixing. This setup prevents dead zones where sedimentation could occur.
Applications of Eductor Nozzles
Eductor nozzles find applications in various industries:
Conclusion
Eductor nozzles are invaluable tools in maintaining fluid uniformity in tanks. By understanding the specific gravity of the liquid, the volume of the tank, and the appropriate sizing and positioning of eductors, one can ensure efficient and effective mixing, preventing sedimentation and ensuring consistent fluid properties throughout the tank. Their versatility and efficiency make them a preferred choice in many industrial applications, contributing to improved process performance and product quality.