Special purpose inline mixers are a range of complex machines and systems which deliver very good uniform dispersions, normally in particular fluid applications, including those at the nano scale. For example, high pressure valve homogenisers are used in the processing of milk to ensure that the milk fats droplets are reduced in size and evenly dispersed throughout the bulk. This stops the cream separating from the milk. The inline mixer comprises a very high pressure pump and a controlled valve nozzle through which the fluid is forced at very high velocity to rupture the fat droplets through extensional stressing. The jet impinging mixer is another type of disperser which uses high velocity fluid streams, except that in this case, the fluid impinges on a plate or contra-jet to rupture the droplets or particles using impact stressing. Inline mixers and membrane mixers provide extremely small droplet sizes, although their cost, complexity and fragility mean that few are used in medium to large volume production applications.
Apart from the above factors influencing horsepower inputs is the relative dissolving rate or reaction rate between gas and liquid. Some gases absorb or react rapidly particularly in the initial stages of the reaction. Others are considerably slower to react. The slower reacting applications require a finer gas dispersion and therefore greater horsepower input.
There are theories and formulas put forward as the key to scale-up, but the mixing characteristics of inline high shear mixers are complex and no single rule can reliably be applied. Rotor tip speed, workhead design, power input, volume turnover, liquid rheology (characteristics of the liquid under shear) and viscosity all affect the end result. However, with more than 60 years experience in helping clients solve some of the most difficult mixing challenges, We can offer expert advice and ensure you obtain the right inline high shear mixer for your application.
bio-equip.cn
中文
