SHAKEN and stirred
15 Jan 2000
Mixing and blending of reactants or ingredients is vital to the process industry and is still the subject of considerable research. Turning the research into commercial equipment is producing a stream of innovative products, some of which are described here and on the following pages.
Efficiency of mixing and blending operations is the goal of many manufactuers looking to provide novel solutions to customer demands.
Maelstrom Advanced Technologies is one such firm taking advantage of demanding specialities production. One of Maelstrom's founding brothers Peter Brown says: `Some speciality emulsions cannot be made using conventional technology. We are having to develop extremely exotic machines to meet requirements.'
Maelstrom has isolated a number of efficient micro mechanisms for mixing and blending in its patented mixing head. The IPM mixing head comprises three cylinders. The inner and outer cylinders are joined and have a motion relative to the middle cylinder. Flow through the channel provides extensional and shear flow stresses for dispersive mixing. The extension mechanism stretches the liquid flow then cuts it. Flow between channels provides distributive mixing. In one test, a small portable IPM mixer formed 50 litres of complete, persistent oil and water emulsion in under 40seconds without stabilising chemicals.
Like Maelstrom, Chemineer also finds equipment development is led by new chemicals. Neil Cathie of Chemineer says: `Speciality chemicals are putting pressure on us. We've had to fill in gaps in our range to meet demand and offer a complete range, from high shear mixers for emulsification to low shear machines that provide movement in sewage treatment tanks.
`We develop products which require careful specifying and they want a company that gives a complete service.' Chemineer now offers specifying software for picking the right equipment for the process.
Sulzer harnesses advances in computational fluid dynamics (CFD) to refine its mixer designs. Sulzer has recently developed, using CFD techniques, the SMI low viscosity static mixer for turbulent flows. Sulzer md Jeff Coe says: ` We can achieve process intensification with the help of static mixing technology. In a loop flow reaction process, static mixers can be retrofitted into a process. This needs less energy, maintenance, and saves space.'
Jet pumps are another low cost, low maintenance method of mixing to aid process intensification. Niro designs and manufactures this simple mixing mechanism for gases, vapours, liquids or solids. The jet pump emits a high velocity jet of the motive medium through a nozzle which draws in any surrounding material, mixes it with the motive stream, propelling it forward.
These developments show that mixing and blending technology is anything but stagnant and with correct application, add to the overall internal efficiencies of any process plant.
