Mixing is a ubiquitous operation in process engineering. It is not only used for combining materials, but also for promoting heat and mass transfer, increasing aeration, suspending solids, and modifying material structure. Measurement techniques have the potential to optimise industrial mixing processes and improve product quality by monitoring critical process parameters. Real-time sensing techniques that do not require manual material sampling are of particular interest owing to their automatic data acquisition capability. This makes them suitable for use in control systems for process automation and eventually as connected sensors in Industry 4.0. This review article focuses on these measurement techniques, defined as in- and on-line, along with their capability for implementation in industrial processes. The applications reviewed include liquid–liquid, gas–liquid, solid–liquid, solid–gas–liquid, in addition to solids blending. A technique selection section discussing the decision-making process when choosing a sensor and a summary table including the advantages, disadvantages, applications and limitations of each technique are provided. The article concludes by discussing the future of monitoring techniques for mixing processes.

A review of in-line and on-line measurement techniques to monitor industrial mixing processes

Recent trends and future perspective of pharmaceutical wet granulation for better process understanding and product development

A Statistical Analysis of Powder Flowability in Metal Additive Manufacturing

Laser powder bed fusion (LPBF) is a powder-based Additive Manufacturing (AM) technology, where the quality control of powder feedstock is critical as the particle packing on the powder bed and laser–particle interaction during laser melting influence the quality of the final parts. In this work, two AlSi10Mg powder batches with satellite particles and non-satellite particles were used to fabricated LPBF AlSi10Mg samples, and the influences of the different powder properties on the defect, microstructure, and surface morphology were quantified. The satellite and agglomeration of powder leads to the formation of the large powder cluster and poor powder flowability and subsequently forms the inter-particle gap left in the powder bed. In the LPBF process, these powder properties can cause uneven recoating and rough surface, which continues to accumulate, eventually forming internal defects such as lack-of-fusion or unfilled irregular shaped defects in parts.

Influence of satellite and agglomeration of powder on the processability of AlSi10Mg powder in Laser Powder Bed Fusion

Heat and mass transfer as well as chemical reactions in technical processes can be enhanced by using electric fields. This paper provides an overview of current fundamental and applied research as well as potential technical applications of electric fields in energy and process engineering. This includes electrosprays, technical combustors as well as electrochemical reforming and plasma gasification of waste or biomass. Other emerging fields are plasma technologies for treatment of water, surfaces and gases including flue gases. In particle or aerosol-laden flows, plasmas are used to promote particle nucleation and surface growth for controlled nanomaterial synthesis. Furthermore, non-invasive diagnostics based on electromagnetic fields and electric fluid properties are relevant techniques for online control and optimization of technical processes. Finally, an overview of laser-based techniques is provided for studying electro-hydrodynamic effects, temperature, and species concentrations in plasma and electric-field enhanced processes.

P.J. Clark

Papers

Using a Freeman FT4 rheometer and Electrical Capacitance Tomography to assess powder blending