Tank Mixing Eductors

Tank Mixing Eductors — In-Tank Jet Eductors

RTM TLM521 tank mixing eductors provide an effective way to mix liquids in open or enclosed tanks. They produce an intimate mixing action between the components of a liquid, while keeping the contents of the tank in constant motion. In many cases they produce a mixing action that cannot be duplicated using mechanical methods.

RTM TLM521 tank eductors can handle a variety of viscosities and types of liquids, including slurries and suspensions. Their thorough mixing action makes them especially useful for maintaining uniform liquid characteristics throughout the tank contents, such as temperature, pH, or solids distribution. The RTM TLM521 tank eductor is also used to prevent separation of non-mixable liquids or stratification of liquids having different specific gravities.

Tank mixing eductors offer low initial cost, lightweight and easy installation. They are inherently non-clogging and with no moving parts, require little or no maintenance. Tank eductors allow the use of a smaller recirculating pump than normally would be needed to move a given volume of liquid. This saves energy while providing more effective mixing and circulation.

How Tank Mixing Eductors Work

Tank mixing eductors are innovative devices that efficiently mix liquids in tanks without any moving parts. They operate by directing a high-velocity stream of fluid to create a low-pressure zone, which effectively draws in the surrounding tank contents. This process generates a highly uniform mixture, proving effective even in challenging applications like blending slurries and suspensions.

Typically, tank mixing eductors are installed at the bottom of a tank and connected to a recirculating pump. The pump supplies the motive fluid, often water or another low-cost fluid, which the eductor then converts into a high-velocity stream to entrain the surrounding liquid from the tank. The resulting mixture is discharged back into the tank, establishing a continuous mixing loop.

Industries Served

Key Advantages

• Low initial cost and minimal maintenance requirements.
• Capability to handle diverse viscosities and liquid types.
• A gentle mixing action that helps preserve product integrity.
• Absence of moving parts, eliminating risks of contamination or explosion.
• They are available in materials to suit a variety of applications in food, chemical, refining and other process industries.

Turnover Rate

The rate at which fluid in the tank must be completely turned over will determine the overall capacity of the tank eductors needed. When the inlet pressure supplied to the tank eductor is within a range of 20 to 70 PSI (133 to 483 kPa), 3–5 gallons of tank contents can be mixed for every gallon of operating fluid passing through the tank eductor. That is, the volume of fluid discharged from the tank eductor will be four times greater than the volume of operating fluid entering the circulating tank eductor inlet.

The ratio of tank contents that can be mixed for each gallon of operating fluid will be approximately 2.6:1 for pressures outside the 20 to 70 PSI range.

In fluids such as water or mineral oil (Newtonian fluids), the length of the tank eductor discharge plume increases proportionally with increased operating fluid pressure. Flow will be evident one foot away from the tank eductor discharge for every 1 PSI of pressure drop across the nozzle (or one meter away for every 23 kPa pressure drop).

Tank Shape and Size

Tank shape and size influence the placement and number of circulating tank eductors required to assure even agitation of the entire volume of fluid. A spherical tank with a single circulating tank eductor makes the best use of the mixing and flow characteristics of the circulating tank eductor. With no corners to impede fluid flow, the fluid circulates evenly and naturally. A single circulating tank eductor will often be sufficient to circulate the entire tank contents.

The angular intersection of surfaces in cylindrical, square or rectangular tanks can interrupt fluid flow patterns and cause fluid stagnation in these areas. A single circulating tank eductor, mounted as shown in the illustration, will tend to minimize this effect. However, multiple circulating tank eductors can often produce more efficient mixing when using these tank shapes.

Long, narrow tanks such as tank trucks or railroad cars, normally require multiple circulating tank eductors when the ratio of their length to diameter is greater than 2:1. Larger tanks of any shape may require multiple circulating tank eductors to maintain agitation in all parts of the tank.

NCI Tank Eductor Performance Table — Model TLM

Operating Fluid Flow — GPM (m³/minute) at Pressure Differential — Inlet to Tank Pressure — PSI (kPa)