Transvac Tank Jet Mixers are a mass momentum exchange device which uses the energy of pressurised liquid to entrain, mix and pump a secondary liquid. The principle is used for many process applications including blending, solids suspension, dilution and heat distribution.
In operation, pressurised motive liquid is discharged through the jet nozzle into the suction chamber. The change from pressure energy to kinetic energy (velocity) creates a region of low pressure that entrains liquid from within the process vessel via the open suction ports. The motive and suction liquid streams combine and mix under high shear conditions in the venturi diffuser. The resulting mixture is then discharged into the bulk of the process liquor as a high velocity turbulent jet.
Standard Transvac Tank Jet Mixers entrain 3 parts suction liquid for every 1 part motive liquid with the discharge jet of 4 parts inducing further secondary mixing.
- No moving parts
- No splashing or aerosol created
- Operates at variable depths
- No bridges or bearings used
- No in-tank maintenance needed
- Evenly distributes mixing
- Controllable mixing
- Simple, reliable and robust
Each Tank Jet Mixer is designed to suit the process mixing requirement and single Mixers or a number of mixers mounted on an intank manifold are available. Transvac can offer the basic mixers or a complete system including pipework, pumps and valves.
Materials of construction are chosen to suit the process conditions, common materials include stainless steel, carbon steel, Polypropylene, PVCu, PTFE, and GRP. Hygienic designs are available for potable water applications
Examples of Transvac Tank Jet Mixers (from l-r) in Stainless Steel, PEEK, Duplex, Carbon Steel, Hastelloy, Polypropylene and Stainless Steel x3
Tank Mixing Performance
A Transvac Jet Mixer can normally be employed on any application in which the process liquid is capable of being handled by a centrifugal pump. The overall capacity of the Jet Mixing System is determined by the rate at which the liquid in the process vessel is completely rotated. Other important factors such as liquid volume, viscosity, specific gravity, size and percentage of solids as well as vessel geometry are used to determine the number and orientation of Jet Mixers in the system.
Because of their ability to entrain surrounding process liquid from within the mixing vessel, each Jet Mixer can achieve a discharge flowrate equal to 4 times it's motive liquid flowrate. Thus the time to rotate the entire vessel contents is simply V/(4Qm), where V is the vessel working volume and Qm is the motive liquid volume (when operating at pump differential pressures between 1 and 6 bar). Jet mixer designs are also available to suit specific applications outside this pressure range.
In general, a single Transvac Jet Mixer can effectively mix 100 to 400m3 capacity deep vessels and 5 to 100m3 capacity shallow vessels. At operating depths less than 1 metre, foaming or surface breakthrough may occur. For every 1 bar perssure drop across the Jet Mixer turbulence will be experienced for upto 5 meters within the mixing vessel. The venturi action can be employed to also entrain atmospheric air where some biological treatment is advantageous during mixing.
The standard operating characteristics outlined above apply to Newtonian liquids. Special design criteria are applied to Thixotropic (shear thinning) and Dialatent (shear thickening) liquids.
Tank Jet Mixer Product Range
There are 3 configurations of Transvc Jet Mixers, covering most applications. Custom designed units can also be provided to meet specific process requirements.
Free Standing or Slide Rail Design
Designed to stand on the vessel floor, the free standing model can be installed without the need to stop the process or drain the vessel contents and is an ideal design for emergency and standby applications. The slide rail mounted model can be removed without the need for a crane.
This model is designed so that the pump is external to the process vessel, mounted at ground level, to aid pump servicing. The design is attractive when mixing hazardous liquids as there are no moving parts in the process vessel. A single pump can be combined with a multi-jet mixing system installed on an in-tank manifold to ensure complete mixing large capacity vessels.
In-line models known as liquid jet pumps are designed to self entrain and mix predetermined quantities of a secondary liquid before pumping the mixture to a recieving vessel.
Typical Water Treatment Related Applications
General Mixing / Blending
- Municipal and Industrial Sludges - Digesters mixed to promote ideal process conditions. Pre and post digestion sludge holding tanks mixed to prevent stratification
- Odour control - Municipal / Industrial sludge balance tanks mixed to prevent anaerobic conditions (optional atmospheric air entrainment to assist process)
- Mix corrosive / hazardous waste on effluent treatment plants
- Neutralisation mixing duties using phosphoric, hydrochloric and sulphuric acids on water treatment
- Agitation of resin beads for water treatment