Process intensification is recognized as a promising strategy to satisfy the objectives of sustainable development and economic competitiveness. Unfortunately, no general methodology still enables to choose the best available technologies from the many potential solutions. This work describes a step-by-step methodology that guides engineers from a given problem to a list of existing appropriate intensified devices. The first step of the methodology consists in identifying the process limitation among a list of 16 possibilities that cover a large spectrum of cases. Then, the methodology relates, through a pre-filled connection matrix, the identified limitations to a set of intensification strategies such as geometric (micro)structuring, periodic operation or multi-scale design. The third step relates these strategies to a list of technologies that apply these strategies or in which they can be applied. The matrices enable to sort these technologies by relevance with respect to the initial problem. The final step provides quantitative charts to compare the characteristics of these potential solutions with the specifications of the problem. The methodology not only yields to a short list of appropriate solutions to be technically designed and economically assessed, but also to a list of innovation strategies.

Methodological framework for choice of intensified equipment and development of innovative technologies

Applicability of coagulation-flocculation process by the Orchis mascula tuber starch as a novel natural coagulant was investigated for the first time in the treatment of oily-saline wastewater. Three inputs variables (pH, coagulant dose, and contact time) and two outputs of chemical oxygen demand (COD) and turbidity (TU) were studied for the proposed system. Orchis mascula tuber starch showed a remarkable performance on treatment of bilge water at the optimum conditions (4 mg L−1 of coagulants dose, pH of 5.0, and contact time of 15 min), with COD and TU removal efficiencies of 92.21 % and 90.63 %, respectively. Also, this material could remove the surfactant and oil-grease up to 23 % and 93 %, respectively. The face-centered central composite design-response surface methodology (FCCCD-RSM) and multivariate adaptive regression splines (MARS), which were used comparatively for the first time in the quantitative evaluation of the studied coagulation-flocculation process, revealed satisfactory predictive performances (R2 > 0.97) for both COD and TU removals. The kinetic study concluded that the second-order model performance was superior to the first-order model. Moreover, the bonding between the particles was also observed from the Fourier-transform infrared spectroscopy (FTIR) analysis of the Orchis mascula tuber starch.

Application of Orchis mascula tuber starch as a natural coagulant for oily-saline wastewater treatment: Modeling and optimization by multivariate adaptive regression splines method and response surface methodology

Effect of impeller clearance on floc growth behaviors in a baffled square stirred-tank reactor: Flocculation-test and CFD-aided studies

https://hal.archives-ouvertes.fr/hal-02292121/document

Estimation of characteristic coagulation time based on Brownian coagulation theory and stability ratio modeling using electrokinetic measurements

The process of colloidal drying gives way to particle self-assembly in numerous fields including photonics or biotechnology. Yet, the mechanisms and conditions driving the final particle arrangement in dry colloidal layers remain elusive. Here, we examine how the drying rate selects the nanostructure of thick dried layers in four different suspensions of silica nanospheres. Depending on particle size and dispersity, either an amorphous arrangement, a crystalline arrangement, or a rate-dependent amorphous-to-crystalline transition occurs at the drying surface. Amorphous arrangements are observed in the two most polydisperse suspensions while crystallinity occurs when dispersity is lower. Counter-intuitively in the latter case, a higher drying rate favors ordering of the particles. To complement these measurements and to take stock of the bulk properties of the layer, tests on the layer porosity were undertaken. For all suspensions studied herein, faster drying yields denser dry layers. Crystalline surface arrangement implies large bulk volume fraction (∼0.65) whereas amorphous arrangements can be observed in layers with either low (down to ∼0.53) or high (∼0.65) volume fraction. Lastly, we demonstrate via targeted additional experiments and SAXS measurements, that the packing structure of the layers is mainly driven by the formation of aggregates and their subsequent packing, and not by the competition between Brownian diffusion and convection. This highlights that a second dimensionless ratio in addition to the Peclet number should be taken into account, namely the aggregation over evaporation timescale.

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Role of particle aggregation in the structure of dried colloidal silica layers.

Aggregation of acrylic latex is investigated inside tubular millireactors working under laminar hydrodynamic conditions. The size distribution and fractal dimension of aggregates are measured using light scattering. Results show that the equilibrium between rupture and aggregation is achieved quickly, allowing the study of cluster size distribution and shape at the aggregation/rupture steady state. Both laminar hydrodynamic conditions and high shear rate are suspected to promote the formation of aggregates with a high fractal dimension, which means that the particles are almost spherical, thereby offering an interesting alternative to conventional batch processes. These results can provide useful information for industries aiming at producing aggregates at specified size and quality.

https://hal.archives-ouvertes.fr/hal-01769589/document

Aggregation and breakup of acrylic latex particles inside millimetric scale reactors

This study compares the hydrodynamics in three millimeter-scale continuous reactor geometries that can be easily used in laboratories and industries – a straight tube, a coiled tube and a Dean-Hex reactor – via numerical simulations and analyses the data in a way that is specifically relevant to coagulation processes, thereby offering insights for engineers to develop new coagulation reactors. A numerical approach based on Lagrangian particle tracking is presented to better understand the impact of the geometry and flow on properties that influence coagulation. The results show that the Dean-Hex meandering geometry provides narrower residence time and shear rate distributions, as well as higher mean average shear rates and Camp number distribution than the other geometries. This is attributed to the generation of transverse flows and radial mixing in the Dean-Hex reactor and suggests that a faster and more homogenous coagulation can be expected.

/pdf/towards-the-design-of-an-intensified-coagulator-e0jkrmest9.pdf

Towards the design of an intensified coagulator

Prediction of droplets characteristic diameters and polydispersity index induced by a bifluid spraying nozzle by the means of dimensional analysis

/pdf/reactive-liquid-liquid-extraction-of-bio-based-3-14ul1opp.pdf

Reactive Liquid-Liquid Extraction of Bio-Based 3-Hydroxypropionic Acid Using a Biocompatible Organic Phase Containing a Tertiary Amine: A Model-Based Approach to Elucidate Dominant Mechanisms

K. Lachin

Papers

Aggregation and breakup of acrylic latex particles inside millimetric scale reactors

Estimation of characteristic coagulation time based on Brownian coagulation theory and stability ratio modeling using electrokinetic measurements

Towards the design of an intensified coagulator

Prediction of droplets characteristic diameters and polydispersity index induced by a bifluid spraying nozzle by the means of dimensional analysis

Reactive Liquid-Liquid Extraction of Bio-Based 3-Hydroxypropionic Acid Using a Biocompatible Organic Phase Containing a Tertiary Amine: A Model-Based Approach to Elucidate Dominant Mechanisms