When creating a fluid or pneumatic conveyor system, eductors can be a good options in place of fans, blowers, and pumps. Eductors are jet pumps to create a vacuum that can simplify a system and improve overall efficiency. They come in many different designs, and can be customized to accommodate the needs of various conveying systems.
Eductors have a lot to offer and are definitely an avenue that’s worth exploring when creating a conveying system. Let’s take a look at what they are and how they work.
What are eductors?
Also known as a liquid jet pump, an eductor is a tool that pumps air, gas or liquid. Eductors require only a motive or driving fluid to operate, and they have no moving parts. This flexibility allows the tool to move a lot of various materials with low ongoing maintenance or troubleshooting.
How do eductors work?
Eductors are simple pumps that use the Venturi effect. The Venturi effect is essentially a reduction in fluid pressure that results when a gas or liquid flows through a constricted section of a pipe. The pumps rely on pressure and an artificially created vacuum to transport air, gas and liquids. The high-pressure, low-velocity fluid is transformed into a low-pressure, high-velocity fluid.
While there are many different types of eductors, they all work the same way. A fluid, gas or undissolved solid enters the eductor through an inlet and flows through a converging section, which narrows the cross-sectional area, increases the velocity and decreases the pressure of the flow. The product then moves into a constricted throat that further increases velocity and exits into a diverging section that increases the pressure. This design essentially creates an area that has low pressure that allows introduction of a secondary solid, liquid or gas as the motive fluid is pumped from one location to another.
Types of eductors
If an eductor pump appears like a good choice for the production line, it’s important to dive deeper into the various types that are available. They all utilize some type of vacuum to function. With that said, the most common types of eductor pumps include:
- Venturi eductors. Eductor venturi pumps require only a positive pressure from a suitable blower or pump to initiate the conveying process. They’re often used to transport low viscosity liquids, pellets, granular bulk solids and powders in lean phase (dilute) pneumatic conveying systems, and are often found in industries like cement, mining, power generation and food processing.
- Multistage eductors. These eductor pumps operate in multiple stages, as the name suggests. The first stage consists of an inlet, outlet and venturi throat. The second stage has a similar configuration but is used to increase the pressure and vacuum. The characteristics and properties of the second stage can be altered to modify the driving fluid flow rates. These pumps are most suited for wastewater treatment purposes, as they can entrain air and prevent solids from settling.
- Liquid ring eductors. These eductors are rotating positive-displacement pumps that have liquid under a centrifugal force. The centrifugal force on the liquid creates an impenetrable seal between the vanes and the pump housing. Liquid ring eductor pumps are often used as vacuum pumps and to transport gases through a system. They do not add as much heat load to the system and have lower cooling water requirements in comparison to other positive displacement pumps.
- Peristaltic eductors. Peristaltic pumps are low maintenance and simple. They can handle undissolved solids and dirty fluids and can operate with high-viscosity fluids. These pumps work by using a squeezing and releasing motion to move fluids through the pump. The materials are transported inside tubing placed over a roller. As these pumps have a pulsating pumping motion, they may not be ideal for applications that require a smooth continuous flow.
The various eductor pumps are designed for different purposes. As a result, it’s vital to familiarize oneself with the design and the overall use to make an informed decision on how to integrate each pump into a conveying system. The right type of features and specifications can improve the overall eductor production by a significant margin.
Why are eductors used?
There are many reasons why eductors are popular solutions in the conveying industry. For one, they prevent product clumping and improve operational speed and efficiency. These pumps also avoid problems like plugged filters. They’re easy to install, set up and use, and they’re even easier to maintain and clean. The design will have a huge influence on the overall efficiency and flow rate.
As a result, they’re often found in industries such as industrial processing, wastewater treatment, chemical processing and food production. The composition of the tubing also needs to be considered, depending on the application and chemical compatibility.
Many industries use eductors as a standard, but they are underutilized in many types of processing. They prevent contamination and can improve the efficiency of the system. The lack of moving parts ensures minimal maintenance and there are fewer blockages to deal with.
Most importantly, installation is relatively simple and they’re easy to use. They come with digital interfaces and other features. Because these pumps rely on the venturi effect, they have few parts and are easy to maintain.
Incorporate eductor pumps in the conveying system
Due to the various benefits that can be enjoyed with eductor pumps, it’s no wonder they are popular in the conveying industry. They’re used in many different applications. It’s wise to consider incorporating them into new and existing pneumatic and liquid conveying systems to improve operational efficiency and lower production costs. Click here to learn more.
