Flow problems arising in a papermaking machine due to the multiphase nature of pulps strongly affect the machinery effectiveness and paper quality. That is why cross-flow distributors and central (or circular) flow distributors, which ensure the uniformity of solids distribution, are among the most important headbox components. In Poland, cross-flow distributors are mostly used. Hydrodynamic and rheologic calculations of those devices are carried out using finite element techniques of fluid dynamics and fluid-flow simulation software. In some of the state-of-the-art headboxes, e.g. in the Valmet Sym Flo Headbox, edge flows, misalignment angle profiles, and slice lip adjustment controls are effectively used to solve the flow problems. Dilution headboxes with consistency, viscosity, flow rate and orientation angle profiling are recommended.
