Principles of Operation



Principles of Operation

Liquid / Liquid laminar flow of miscible fluids

Flow Division

The main   mechanism  in laminar flow in a static mixer (Reynold's number < 2000) isflow division. Vikas  Static  element styles are either helical or pseudo-helical and are arranged in a series of alternating left and right hand 180° twists. The leading edge of an element, which is on a diameter, is at 90° to the trailing edge of the upstream element.

In flow division, the leading edge of the first element splits the fluids entering the mixer into 2 streams, which are then rotated through 180°. The second element splits the flow again, this time into 4 streams, followed by a further rotation, in the opposite direction, through 180°. The third element repeats the process by splitting into 8 streams, and so on. As the number of streams or layers increases, the layer thickness decreases. Typically, 12 to 24 elements are required to provide a complete mix.

Mixture quality is a function only of mixer diameter and number of elements and, in laminar flow, is independent of flow rate and viscosity.

Liquid / Liquid turbulent flow of miscible fluids

At higher Reynold's numbers, much greater than 2000, a second mixing mechanism, acting simultaneously with flow division, becomes important to the overall mixing process:

Radial Mixing

In general terms, the fluid viscosity in turbulent flow is lower than in laminar flow. The element shape is now able to impart a rotational spin to the fluids, which changes direction with each succeeding element. Fluids are constantly moved from the pipe centre to the pipe wall and back again, with the interface between elements a particularly active zone. This mechanism is called radial mixing, which dominates the flow division mechanism in turbulent flow. It very rapidly eliminates radial differences in, for example, composition, colour, pH, temperature and velocity.

The number of mixing elements required to achieve a fully homogeneous mix in turbulent flow applications is much less than in laminar flow and is typically 1.5 to 4 elements.

Liquid / Liquid turbulent flow of immiscible fluids

The radial mixing mechanism is important in reducing radial differences in velocity and therefore shear rate. The even shear history results in a predictable average droplet size where approximately 80% of the dispersed phase is within ±20% of the average droplet size. An open pipe, without controlled mixing, provides a huge range of droplet sizes with far less surface area of contact between phases.

The average droplet size is velocity dependent, with the terminal droplet size approached after 4 elements.

Water & Wastewater Treatment

Vikas Static has the most extensive range of Motionless Mixers, for pipes and open channels, suitable for blending, dosing and gas / liquid mass transfer applications in:

  • municipal and industrial water treatment

  • municipal and industrial wastewater treatment

Vikas Static unique customised approach to static mixer design provides the most effective mixing solutions for both new treatment plants and retrofits to existing plants in an industry wide trend away from continuously stirred tanks

  • : Blade design MixerType
    : SS – 316 Material
    Viscosity range : less than 1500 cps
    Reynolds no. : greater than 500
    : ½ “ to 14”Size range
    Application : Mixing products into water or water like fluids.

  • VW-VMx-01 : using for low viscosity. The faster the fluid moves, the faster mixing. Great for mixing products into water or water like fluids.

  •  

  •  Helical design Mixer
    VW-VMx-02 : using for high viscosity blending application and when
    fluid moves more slowly through the mixer
    Material: SS – 316
    Viscosity range : greater than 1500 cps
    Reynolds no. : less than 500
    : ½ “ to 14”Size range
    Application : Epoxy blending, Fruits into yogurt, Cookies into ice cream, Thermal homogeneity, slurry suspension, Folding/stripping .

  • Customer Benefits

Excellent mixing and dispersing even with widely differing fluid
viscosities
Compact designs
Reduced product degradation due to very short residence time
Mixing of sensitive products under minimal shear stress
No deposits and blockages due to excellent cross-mixing

  • Advantage

Static mixers deliver a high level of mixing efficiency, formation of byproducts can be dramatically reduced.
Low energy consumption
Installation is very easy
Static Mixers are available in all standard pipe sizes and in the case of open channel designs, are available in any size with no upper limit.

  • Industry Served

Pulp and Paper Processing
Pharmaceuticals
Oil Refining
Petrochemicals
Food Processing
Natural Gas Processing
Water and Waste Water Treatment

  • Design Calculation

For calculating element following criteria used :
Reynolds no.= Dvñ/µ

  • Re<10 = 24-36 element
    10 100 1000 Re>10000 = 4 element

  • Pressure Drop Calculation

?P =3.061×10 6 f nsmxpx(u)2 xE
G value calculation
G = v(hf gñ/ìt)
Pipe diameter
(D)in meter = v(4Q/pv)

 

Inquiry us

:
   

© 2016 VIKAS PUMPS & PROJECTS. All rights reserved | Design by Design Museum India