Tank Aeration

Aeration

Transvac Venturi Aerators and Mixers have been successfully implemented for Aeration and Tank Mixing applications throughout a number of industries. These include Oil and Gas, Pharmaceutical, Chemical, Food and Water industries.

Our core capabilities

There are two products available either Venturi Aerators (liquid entraining air) or Venturi Jet Mixers (liquid entraining liquid).

Computational Fluid Dynamics

In order to avoid bypassing of the fluid or dead-spots within the tanks, our in-house CFD team can assess the quality of mixing based on various installation options including manifold layouts, mixer inlet elevations and spool piece angles. Learn more on our Computational Fluid Dynamics page.

Principle of Operation

Transvac Venturi Aerators use the energy of pressurised liquid to entrain air into a  secondary liquid for mixing and pumping purposes. Although atmospheric air is commonly used in this application, blown oxygen is also an option.

The Transvac Venturi Aerator uses this principle to entrain air or oxygen (atmospheric or blown) and mix it with liquid for the purpose of aerating and mixing in a process vessel or pipeline. Essentially, recirculated liquid is pumped from the process vessel and into the venturi where it is accelerated through a unique vortexing jet. This results in an area of low pressure and high velocity into which air is drawn and intimately mixed with the liquid under conditions of high shear.

The mixture is then forced through the venturi, receiving a pressure boost sufficient to overcome the backpressure created by the head of liquid in the process vessel. The high energy turbulent plume is freely discharged with a velocity capable of entraining the surrounding liquid, following which, the plume changes to a buoyant low-density mixture rising to the liquid surface to complete the aeration and mixing process.

System Performance

Recirculating pumps provide the liquid motive power and are chosen to suit the characteristics of the fluid and the venturi. Pumps are normally centrifugal type and are either submersible or drywell mounted. The standard motor power for the self-entraining single venturi option is 7.5kW, but will depend upon the application. Multi-venturi systems with single larger pumps are also available.

The ability of the standard Transvac Venturi Aerator to self-entrain air at liquid depths up to 6.5m ensures flexibility over the vast majority of applications. At greater liquid depths efficient operation is still achieved by employing higher pressure pumps or blown air. To accommodate deep process vessels (or unusually high oxygen demands) a Transvac ‘Forced Air Aerator’ has been developed utilising a mechanical blower. High energy efficient aeration and mixing can be achieved in the deepest of vessels (a particular advantage when space is at a premium).

Standard self-aspirating units can operate at tank depths of up to 7 metres and offer typical efficiencies between 1.2 and 1.8 kg02/kWh at standard conditions. High alpha factors, simplicity, reliability and low cost make the Transvac Venturi Aerator very competitive with other forms of aeration equipment on the market.

The action of the Venturi Aerator makes it particularly suited to processes that require directional mixing, such as in ‘race-track’ type oxidation ditches or in-line aeration packaged sewage treatment plants.

Corrosion resistant materials are available where necessary, making our Aerators ideal for mixing applications in hazardous/aggressive liquid or effluent.

The oxygen transfer feature of the Transvac Mixer / Aerator is used to it’s full on food waste balance tank mixing because it can keep the effluent ‘fresh’, avoiding unpleasant odours.

Operating Efficiencies

Our Aerators offer superior oxygen transfer rates and improved performance over many other types of aerating units. This is thanks to the unique vortexing action which provides a high shear gas/liquid interface and extended gas/liquid contact times.

Mixing is of fundamental importance to the overall aeration process efficiency.
The Transvac Venturi Aerator requires less air for oxygen transfer than other aerator types because the recirculated liquid provides significant energy to enhance the mixing process. This results in lower operating costs and beneficial process considerations such as reduced off-gas volumes.

Advantages

Standard Configurations of Transvac self-aspirating units

Materials of construction

Standard Venturi Aerator materials include Stainless Steel, Carbon Steel, u-PVC and Polypropylene. Pumps and ancillary equipment materials are selected to suit the process conditions.

Venturi Jet Mixers

Our Venturi Jet mixers use the mass momentum exchange principle. They entrain, mix and pump air into a liquid by using a pressurised liquid motive.

By installing a simple external recirculation line with a pump, our Aerators can be installed inside a tank, on a manifold, or through-the-wall to offer a mixing arrangement with no moving parts inside the tank. Once installed, our units are virtually maintenance free.

Advantages