Ultrasonic technique to determine particle size and concentration in slurry systems

Research on synergistic erosion by cavitation and sediment: A review

Sediment erosion frequently occurs in areas with high incidences of cavitation. The collaborative impact of abrasion and cavitation presents a host of challenges, threats, and damages to hydraulic engineering. However, little is known about the synergistic wear mechanism, and research conclusions remain inconsistent. In this work, relevant studies on synergistic erosion have been collected, classified, and analyzed. Presently, research on synergistic wear primarily operates at the macro and micro levels. The microscopic level enables the visualization and quantification of the process by which particles gain momentum from bubbles, the trajectory of particle acceleration, and the mechanism that triggers strong interactions between bubble-particle. At the macro level, erosion is understood as the summation of damage effects on the wall that is caused by the interaction between a plethora of bubbles of varying scales and numerous particles. The synergistic bubble-particle effect is reflected in the dual inhibiting or promoting mechanism. Furthermore, while numerical simulations could be realized by coupling cavitation, multiphase flow, and erosion models, their accuracy is not infallible. In the future, the dual role of particles, and particles driven by micro-jets or shock waves should be fully considered when establishing a combined erosion model. In addition, enhancing the influence of flow field and boundary parameters around bubbles and utilizing FSI would improve the predictive accuracy of erosion location and erosion rate. This work helps to elucidate the combined wear mechanism of hydraulic machinery components in sediment-laden flow environments and provides a theoretical basis for the design, manufacture, processing, and maintenance of hydraulic machinery.

Critical review of different aspects of liquid-solid mixing operations

Mechanically stirred slurry tanks are utilized in several industries to perform various unit operations such as crystallization, adsorption, ion-exchange, suspensions polymerization, dispersion of solid particles, leaching and dissolution, and activated sludge processes. The major goal of this review paper is to critically and thoroughly analyse the different aspects of previous research works reported in the literature in the field of liquid-solid mixing. This paper sheds light on the advantages and limitations of various particle concentration measurement methods employed to assess the suspension quality and the extent of solid suspensions in slurry reactors. Attempts are being made to identify and compare various mathematical models and methods to quantify particle dispersion and distribution in slurry reactors. It has been shown that various factors such as geometric configurations, agitation conditions, and physical characteristics of liquid and solid have pronounced influence on local suspension quality and power consumption. Computational fluid dynamics (CFD) modeling can be extremely useful in assessing the suspension of solid particles in slurry tanks. A critical review of different scale-up procedures employed for solid suspension and distribution in liquid-solid systems is presented as well. The findings of this review paper can be useful for future research works in liquid-solid mixing.

On demand for new process analytical technologies applied to injectable drug products

Currently, in the pharmaceutical manufacturing process of injectable drug products, quality is still assessed under a quality-by-test system, wherein the product quality is evaluated at fixed manufacturing steps and in the end product. The introduction of the quality by design (QbD) approach, supported on process analytical technologies (PAT) is changing this paradigm. Efficiently understanding the process parameters and material attributes and how they affect the quality profile of the final product is increasingly a real need. In this context, all manufacturing steps should be ideally monitored as they are carried out, following the evolution of quality throughout the entire process. The PAT application to injectable drug products is still in its infancy since several constraints are raised mainly due to the solvent influence. This mini-review aims at identifying PAT potentially suitable for injectable analysis and foster their adoption by the pharmaceutical industries in their industrial processes, paving the way to enhanced quality and efficient processes.

Acoustic spectroscopy: A powerful analytical method for the pharmaceutical field?

Acoustics is one of the emerging technologies developed to minimize processing, maximize quality and ensure the safety of pharmaceutical, food and chemical products. The operating principle of acoustic spectroscopy is the measurement of the ultrasound pulse intensity and phase after its propagation through a sample. The main goal of this technique is to characterise concentrated colloidal dispersions without dilution, in such a way as to be able to analyse non-transparent and even highly structured systems. This review presents the state of the art of ultrasound-based techniques in pharmaceutical pre-formulation and formulation steps, showing their potential, applicability and limits. It reports in a simplified version the theory behind acoustic spectroscopy, describes the most common equipment on the market, and finally overviews different studies performed on systems and materials used in the pharmaceutical or related fields.