Product Design
The product design is defined by two features:
1) It makes use of pressure energy in a liquid flow to drive a gas flow. This is achieved by converting the pressure energy to kinetic energy by accelerating the flow through constricted channels. This causes a vacuum to form in the constrictions which sucks gas into the flow through openings within the constricted channels. The gas is then swept away by the liquid, leading to a continuous flow.
2) It generates a bubbly two phase flow (dispersed gas/continuous liquid) downstream of the constricted channels. The generation of a bubbly flow has two functions: it stabilises the flow, reducing the energy required to drive a given gas flow rate, and it promotes mass transfer between the two phases due to high interfacial area density.
The constricted flow channels are formed by placing a streamlined insert into a cylindrical pipe . The basic design of the insert consists of a central, torpedo shaped hub, connected to the pipe walls by six aerofoil blades. Six constricted flow channels are therefore formed by the gap between the hub, blade faces and pipe wall. Two main variants of the basic design have been developed:
1) Zero angle of attack (ZAA2) – The aerofoil blades are straight and exert no rotational forces on the flow.
2) Non-zero angle of attack (NZA2) – The aerofoil blades are angled and exert a rotational force on the flow, generating a swirling flow downstream of the device.
Both designs aim to improve the efficiency of a traditional venturi device by reducing large scale secondary flow currents which increase energy demand while retaining high levels of linear shear which enhance mass transfer rates.
Our ZAA2 design has particular application for larger volume flows such as those found in hydropower generation, irrigation systems, groundwater treatment and storm water management.
The swirl generated by the NZA2 design has three additional effects:
1) When the flow is oriented horizontally, the rotational acceleration counteracts gravity and suppresses bubble rise, enhancing mass transfer due to prolonged existence of bubbly flow.
2) Turbulence intensity in the region downstream of the device is reduced, leading to reduced energy demand.
3) It further enhances mass transfer rates.
Our NZA2 design has particular application for lower volume flows such as those found in municipal and industrial treatment flows.
The multi-bladed aerofoil inserts into a cylindrical pipe as shown typically below:
