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Tank Aeration

Tank Aeration

Transvac Venturi Aerators are a mass momentum exchange device which uses the energy of pressurised liquid to entrain, mix and pump air into a secondary liquid.

 

We have been supplying Venturi Aerators and Mixers into the Water Treatment industry for decades, with hundreds of projects successfully carried out. As a result, we are able to share extensive process and project expertise to support your next tank aeration projects.

 

 

Tank Aerators : Principle of Operation

 

Transvac Venturi Aerators use the energy of pressurised liquid to entrain air (or oxygen) into a secondary liquid for the purpose of aerating and mixing in a process vessel or pipeline.

 

Recirculated liquid is pumped from the process vessel and into the Aerator 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 this, the plume changes to a buoyant low-density mixture rising to the liquid surface to complete the aeration and mixing process.

 

As well as our Venturi Aerators (liquid entraining air), we also offer Venturi Jet Mixers (liquid entraining liquid) to provide tank mixing/agitation.

Tank Aeration with Venturi Aerators
Transvac Venturi Tank Aerator

Our Core Capabilities : To support your next Aeration Project

In-house process design, mechanical design and manufacture of Jet Mixers

In-house CFD Analysis to determine the optimum mixing arrangement

Customised material options including plastics, metals and exotics

Manifold design and supply

Structural support or skid design and supply

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.

 

 

Standard configurations of self-aspirating units

 

  • Free standing
  • Floating
  • Through-wall
  • Guide rail mounted

Through-wall Aerator

Single-barrel Venturi Aerator on raw sludge tank 

Advantages of Venturi Aerators for Tank Aeration

No moving Aerator parts

High oxygen transfer

Minimal maintenance

Virtually silent operation

No aerosol spray

Simple to install and retrofit

Materials can be customised to suit the process

High alpha factors

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.

Transvac Venturi Aerator

Transvac Size 6 Venturi Aerator with 10” Tank Connection

Materials of construction

 

Depending on your specific requirements, we can manufacture from Stainless Steel, Carbon Steel, u-PVC and Polypropylene. Pumps and ancillary equipment materials are selected to suit the process conditions.

 

For more information on materials of construction, please visit our Materials page here.

Aeration proven through CFD

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 (CFD) page.

Using CFD to model efficient Tank Aeration

CFD used to model Tank Aeration