Influence of Mixing System Design and Operating Parameters on Dissolution Process

Abstract

Over recent years, the solid dissolution rate in liquid has been the subject of intense and profitable scientific developments. This work aims to study the influence of hydrodynamics on the dissolution rate of solid in water. The impact of the mixing system design was also investigated. The dissolution process can be followed through several parameters. First, experimental results were validated by kinetic models based on mass transfer coefficients such as the Hixson-Crowell equation. The Weibull model and n-order model were also tested. Then, the dissolution time t d,x% was defined as the time needed to reach a given dissolution degree (X). Finally, the dimensionless dissolution number (N t d ) was defined and correlated with the Reynolds number. This correlation provides a more direct and simple link between operating conditions and process efficiency.

Towards a better control of dairy powder rehydration processes

“…This step was first observed by Hixon and Crowell (1931). This has also been observed more recently for mineral powders such as sodium hydroxide pellets (André, Richard, Le Page, Jeantet, & Delaplace, 2012). The last step deals with final reduction of particle size.…”

“…In this work, such a process relationships were shown to be valid for other dairy powders (NPC, NPC/WPI, NPC/lactose) and mixing systems. Recently, André et al (2012) measured dissolution time for non-food powder (highly soluble particles of sodium hydroxide) dispersed in aqueous solution, using similar approach. For another mixing system, the revolution number achieved by the agitator governed the rehydration time and was almost independent of Reynolds number (range 5000e100,000).…”

Promotion of Chemical Reactions by a Grid in a Shear Mixing Layer

“…Fluid mixing with chemical reactions in a free shear flow like jet and mixing layer is commonly applied in various industrial and environmental situations 1–11. Efficient mixing and reaction are often desired in industry to develop high‐performance devices such as mixers, chemical reactors, and combustors.…”

Inclined-Shaft Agitation for Improved Viscous Mixing

“…Furthermore, baffles are frequently an obstacle for the reduction of power consumption and the enhancement of mass transfer for solids suspension. 13,14 The objective of this work was, therefore, to introduce impeller inclination into a vessel without baffles to enhance the mixing quality by eliminating the segregated regions that are usually present above and below the impeller under laminar conditions. The motivation of this modification was to alter the symmetric flows inside the stirred vessel, aiming to attain complete mixing conditions.…”

“…From the aspect of mineral industries, however, not only the mixing time but also the power consumption are key factors for process design. Furthermore, baffles are frequently an obstacle for the reduction of power consumption and the enhancement of mass transfer for solids suspension. , …”