Static Mixers

Static mixers are inline, passive mixing devices that generate controlled fluid mixing through engineered internal geometry — without any rotating or moving parts. The mixer body contains a series of fixed mixing elements (helical, corrugated plate, tab, or multi-hole types) that repeatedly split, redirect, and recombine flowing fluid streams, achieving efficient mixing through a combination of radial convection, laminar striation, and (at higher Reynolds numbers) induced turbulence. They are among the most robust and maintenance-free components in a continuous flow chemistry or industrial process train, suitable for gas–gas, gas–liquid, and liquid–liquid mixing duties across an enormous range of viscosities and flow rates. The mixing efficiency of a static mixer is quantified by the Coefficient of Variation (CoV) of the mixed stream, with values below 0.05 (5%) considered well-mixed for most process chemistry applications. The number of mixing elements required to achieve a target CoV depends on the Reynolds number, viscosity ratio, and diffusivity of the species to be mixed. For low-viscosity liquids at process flow rates, 6–12 elements typically achieve CoV < 0.01. For high-viscosity or high-density-ratio systems, 18–24 elements may be required.

For flow chemistry applications, static mixers serve as the primary mixing point for reagent addition upstream of tubular reactors and CSTRs, as quench addition mixers in downstream workup, and as heat exchange and solvent exchange contact devices. In pharmaceutical continuous manufacturing, inline static mixers are used for API precipitation, buffer preparation, and pH adjustment. Wetted materials are selected based on process chemistry: SS 316L for general organic and aqueous media; PTFE-lined or Hastelloy designs for HCl, HBr, HF, or corrosive organic streams; PEEK designs for high-temperature acidic or oxidising conditions. All designs can be equipped with injection ports, sampling nozzles, and thermowell connections.