Impact of Process and Machine Parameters in the Charging Section on the Triboelectric Separation of Wheat Flour in a Vertical Separator

Triboelectric separation has recently been investigated as a novel process for dry enrichmentand separation of protein of various crops like wheat flour. The triboelectric effect allows for theseparation of starch and protein particles in an electric field based on their different charging behaviordespite having a similar density and size distribution. Particles are triboelectrically charged in acharging section before being separated in an electric field based on their polarity. While the chargingsection is crucial, the influence of process parameters remains largely unexplored. Thus, the influenceof the charging sections’ dimensions and the particle concentration as process key parameters wasinvestigated experimentally. Varying the length (0, 105, and 210 mm) showed that the protein shiftincreases with the length (max. 0.53%) during separation. Varying the diameter (6, 8, and 10 mm)influenced the charging behavior, resulting in an increase in protein accumulation on the negativeelectrode as the diameter decreased. Varying the mass flow of flour (40, 80, 160, and 320 g·h−1) alsoaffected the separability, leading to a maximum protein shift of 0.61%. Based on the observed results,it is hypothesized that the electrostatic agglomeration behavior of oppositely charged particles isdirectly affected by alterations in machine parameters. These agglomerates have a charge-to-massratio that is too low for separation in the electric field.