New Mixers bring about big energy drop in Cote d’Ivoire chocolate production
In replacing its aging stirring equipment, a major chocolate factory in Cote d’Ivoire has reduced its energy consumption for the process by more than 70%.
Serving eight tanks from 500-litres up to 30m3, agitators made by Mixel (part of the GMM Pfaudler Group), are successfully homogenising, mixing, holding and suspending highly viscous products up to 6300 cps across process temperatures of 95oC to 130oC.
Marvin Bouterra from Mixel, commented: “We’re often brought in to provide an enhanced mixing solution, where the perceived belief is that more power will somehow be the answer. However, with CFD and finite element calculations, we have, in this part of Africa, been able to demonstrate that smaller motors, designed in with the right amount of specially inclined propellers would not only reduce energy costs, but also improve the whole process.”
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He added: “The customer’s tanks in Cote d’Ivoire are all cigar-shaped, which presents the significant challenge of trying to achieve comprehensive mixing in vessels that are extremely high in relation to their diameter.
“Typically for water applications, we’d usually install a single helix to create sufficient axial flow over the height of the tank, but with chocolate, for such a wide variety of operations (mixing, high/low speed, homogenization, heat exchange, storage, blending, preparation and suspension), our design experience of more than 50 years shows that we have to install three, four or even five agitators.”
He continued: “Each ingredient, from cocoa liquor to lecithin, cocoa butter and fat, has its own behaviour in terms of viscosity and density when mixed, so the additional helixes provide sufficient turbulence to obtain a good shear and axial flow that comprehensively mixes the tanks. The mixing of chocolate is mechanically demanding though, and likely to weaken the agitator if it is not specified correctly.”
Mixel also saw clearly that although the chocolate factory’s old flat turbines (inclined at 45 degrees) had functioned quite well, their single-surface, single-tilt-design meant that they were very energy-intensive.
Established in 1969, and with almost 50,000 agitators installed worldwide, Mixel has developed numerous mixing solutions, including its innovative Multiplane propellers, which have the advantage of offering several different inclinations.
Mixel’s overall solution for this Cote d’Ivoire factory also provided mixing with just the right torque for an optimum stirring rate, with turbines installed at the base of each tank to stop solids from settling.
