A common challenge faced by oil and gas operators is the formation of gas hydrate blockages in production lines. There is no consensus on the methodologies and apparatus used to assess gas hydrate blockage risk, and extrapolating laboratory results to field conditions remains a significant challenge. This highlights the importance of comparing different techniques and experimental scales. This study aims to investigate the influence of key variables, such as shear, gas-liquid ratio, water cut, salinity, subcooling, gas composition, and wax content, on gas hydrate transportability at different scales. From an industrial perspective, the objective is to determine the most effective technique for translating laboratory data into field-scale applications. To this end, three experimental setups are employed: a high-pressure rheometer, a rock-flow cell, and a pilot-scale flow loop.

Flow assurance remains a critical challenge in oil and gas production, with hydrate and wax deposition representing two of the most significant risks to safe and continuous operations. This study investigates the coupled transport of gas hydrates and wax in multiphase systems, with a focus on understanding how dispersed wax particles influence hydrate formation and the risk of pipeline plugging. Experiments were performed in a highpressure flow loop using a water-in-oil emulsion (10% water cut), where both flow rate and wax concentration were systematically varied. The results demonstrate that the presence of wax significantly reduces the hydrate volume fraction, thereby mitigating plugging risk. For instance, at a flow rate of 400 L/h, the hydrate fraction decreased from 8.6% in wax-free oil to 1.8% with 5 wt% wax. This effect is linked to the increased apparent viscosity caused by wax precipitation, which promotes particle agglomeration and reduces the active surface area hydrate crystallization. These findings offer new insight into the complex interplay between wax and hydrate multiphase flow systems and suggest that wax presence, under certain conditions, may play a protective role against hydrate plugging.

Tungsten (W), a rare metal, is categorized as a Critical and Strategic Raw Material (CRM) by the European Union (EU), with the highest economic importance of all selected CRMs since 2014. Tungsten and its derivatives are extracted from their commercial raw materials, mainly wolframite [(Fe,Mn)WO4] and scheelite (CaWO4) ores. Subsequently to mining and mineral processing, the W ore is submitted to thermal treatment and hydrometallurgy under aggressive conditions (high pressure and temperature), which are usually applied for the extraction of tungsten compounds. This paper aims to investigate a thermal route for scheelite processing using various selected chemical agents, resulting in a W-bearing material that is capable of being leached under softer conditions. In this context, a thermodynamic study of the interaction between FeWO4, MnWO4 and CaWO4 and various chemical reagents is described. The thermochemical calculations and data modeling show that, among other considerations, the reaction of CaWO4 with magnesium chloride (MgCl2) can lead to the formation of magnesium tungsten oxide (MgWO4), which appears to be more easily leachable than CaWO4. Experimental tests of the reaction of scheelite with MgCl2 appear to validate the thermodynamic predictions with satisfactory process kinetics at temperatures from 725 to 775 °C.

Crystallization is regarded as an important unit operation for separation and purification, as well as the production of solid particles with specified end-use properties. However, it is still difficult to control or to optimize the crystallization process due to the complexity of the coupled phenomena taking place simultaneously in the liquid and solid phases. In order to overcome such drawback, different analytical technologies have been implemented in the literature for monitoring (in situ, at best) the key crystallization parameters, e.g. solute concentration and crystal size distribution, which in turn enhances the comprehension about this operation. In our work, a multi-probe monitoring system composed of acoustic emission, ATR-FTIR and imaging probes was applied to the crystallization of a model system (an aqueous solution of adipic acid) in a semi-batch crystallizer. The crystallization was carried out under two different feed rates and under vacuum or atmospheric pressure. The goal was to demonstrate the usefulness of the multi-probe system for monitoring the crystallization process and to study the influence of the process (stirring rotation speed, cooling speed, etc.) on the acoustic emission. As a matter of fact, the multi-probe system tracked information about the dissolved adipic acid in the liquid phase with the ATR-FTIR spectrometry, while the crystal size, shape and number were monitored with the help of the imaging probe (with image treatment methods). The acoustic emission probes were used to detect the beginning of crystallization and the phenomena of crystal growth and agglomeration

To enhance control and monitoring of industrial crystallization processes, we propose an innovative nondestructive imaging method utilizing in situ 2D vision sensors. This approach enables the acquisition of 2D videos depicting crystal aggregates throughout the batch crystallization process. Our approach is built upon experimental observations, specifically regarding the process dynamics and sensor fouling. It involves dynamic segmentation of observed aggregates, from which quantitative analyses are derived. Notably, our method allows for tracking the evolution of the particle size distribution of crystal aggregates over time and the determination of the growth kinetics of crystals that agglomerate at the sensor air gap. This enables the detection of key stages in the crystallization process and the geometric characterization of crystal aggregate production.

Hydrate formation poses a threat to the safety of petroleum transport in flow lines due to the risk of plugging. In this work, conceptual mechanisms of hydrate formation and plugging in oil-water systems are proposed, based on flow loop tests at 30%, 50% and 80% water cut (water fraction). The experiments were conducted with Kerdane oil, water (with 30 g/L of NaCl) and natural gas at 75 bar and 4 degrees C. The employment of several instruments, such as acoustic emission, permittivity, and flowmeter, to cite a few, allowed identifying the different flow patterns until hydrate blockage and detecting the phase that carries the hydrates. A model based on density measurement is proposed to calculate the fraction of hydrates flowing locally. It was observed that there are local accumulations of most of the hydrates in a small portion of the flowing volume, which, together with deposition, ends up leading to plugging. (c) 2023 Elsevier Ltd. All rights reserved.

Crystallization is regarded as an important unit operation for separation and purification. However, it is still difficult to control or to optimize the crystallization process due to the complexity of the coupled phenomena taking place simultaneously in the liquid and solid phases. In order to overcome such drawbacks, different analytical technologies have been implemented in the literature for monitoring the key crystallization parameters. In our work, a multi-probe monitoring system composed of acoustic emission, spectroscopic and imaging probes was applied to the crystallization of a model system (an aqueous solution of adipic acid). The crystallization was carried out under vacuum or atmospheric pressures. The goal was to demonstrate the usefulness of the multi-probe system for monitoring the crystallization process, with special attention to the information given by the acoustic emission, in terms of absolute energy, and the spectroscopic probes. Firstly, the influence of the crystal load on the absolute energy is demonstrated. Then, it is shown how the absolute energy can capture the modifications in the crystallization dynamics due to the different experimental conditions. Such dynamics can also be observed from other acoustic emission descriptors.

The influence of laser texturing parameters and chemical curing environments on the wettability of flat soda-lime silica glass surfaces was studied by contact angle measurements. The surfaces were textured using femtosecond laser pulses with varying fluence, periodicity, and pulse number. By exposing these textured surfaces to different chemical curing environments, a range of hydrophilicity and hydrophobicity was observed. Experimental characterizations of the roughness produced by the texturing, using the optical profilometer, and contact angle hysteresis measurements showed a transition from a Wenzel regime to a Cassie–Baxter regime, induced by the chemical environment.

The formation of natural gas hydrates in oil and gas pipelines is an important concern due to the risk of hydrate blockage. In order to reduce the expenses with the use of chemicals to avoid hydrate plugging, more studies about the slurry flow and the mechanisms of blockage in flowing conditions are necessary. In this study, it is presented an experimental work combined with a multi-instrumental data analysis to allow monitoring hydrate formation and track the particles in time and space. Acoustic emission (AE) is used in a high pressure flow loop apparatus to capture acoustic waves generated by the flow and to detect the presence of hydrates flowing in the system. The tests are conducted with Kerdane oil, saline water and natural gas at 75 bar and 4 degrees C. Two tests are presented, one at 30 and another at 80% water cut (water fraction in volume). It is shown that, with the absolute energy obtained from the AE sensors, it was possible to detect the beginning of hydrate crystallization and the hydrates displacement in the pipeline, because the absolute energy increases as the collisions of particles generate more acoustic emission. The results show that, for the tests performed, the flow became heterogeneous after hydrate formation, with some regions of the flowing volume containing more hydrates than others. It is also shown that the non-flowing volume of hydrates with entrapped liquid, caused by deposition or settling, can be estimated with AE.

The kinetic behavior of Zircaloy-4 tube samples was examined during high temperature steam oxidation in order to propose a mechanism with detailed elementary steps. The study revealed that steam and hydrogen partial pressures have no effect on the reaction kinetics. Based on these experiments, the kinetic model established herein takes into account the oxide growth and the oxygen dissolution in the metal. A rate-determining step of diffusion of oxygen vacancies in the oxide governs the kinetics of the reaction in both pre- and post-breakaway regimes meaning that the oxide growth and oxygen dissolution in the metal advance at proportional rates.

HT-XRD analyses were performed on Zircaloy-4 sheet samples in steam and oxygen mixtures at high temperatures in order to investigate any possible relation between zirconia phase transformation and the breakaway oxidation. The tetragonal phase fraction decreases for temperatures less than 1000 degrees C. At 1000 degrees C and 1030 degrees C, breakaway oxidation occurred, however, the tetragonal phase fraction remained constant during the isothermal oxidation showing no sudden decrease that could be attributed to the onset of breakaway oxidation. These results demonstrate that the tetragonal-to-monoclinic phase transformation in the external surface of the oxide could not be correlated to the occurrence of the breakaway oxidation.

Les alliages de zirconium sont utilises comme materiaux de structure des crayons de combustible nucleaire pour les centrales nucleaires a eau legere en raison de leurs proprietes neutroniques, mecaniques satisfaisantes et de leur resistance a la corrosion. En conditions nominales de fonctionnement (environ 150 bar et 350°C), les tubes en alliage de zirconium sont sujets a une oxydation maitrisee en presence d’eau pressurisee, servant de caloporteur. La demonstration de la surete des reacteurs nucleaires integre l’etude des scenarios accidentels hypothetiques, tels que l’Accident de Perte de Refrigerant Primaire (APRP). Dans ce scenario, une breche dans le circuit primaire du reacteur peut conduire les crayons de combustible a etre oxydes en milieu de vapeur d’eau a haute temperature (jusqu’a 1200°C). Il a ete demontre [1]–[3] que dans l’intervalle de temperature [900-1050°C] et apres un certain temps d’oxydation sous vapeur d’eau, le phenomene de breakaway peut apparaitre. Il se manifeste par une acceleration de la cinetique d’oxydation, par la perte du caractere protecteur de la couche d’oxyde et par l’absorption d’hydrogene du materiau. Un tel phenomene implique donc une deterioration des proprietes mecaniques de la gaine et menace son integrite pendant et apres le transitoire accidentel. Les mecanismes fondamentaux a l’origine du breakaway sont encore mal connus. Dans ce cadre, ce travail de these a pour objectif de caracteriser les conditions d’apparitions du breakaway et d’ameliorer la comprehension des mecanismes physiques sous-jacents. Pour ce faire, des essais d’oxydation sur des echantillons de Zy-4 en thermobalance symetrique ont permis d’etudier l’influence de la temperature, de la pression partielle de vapeur d’eau et du temps sur l’occurrence du breakaway. La couche d’oxyde formee a ete caracterisee par des observations en microscopie optique et des analyses en DRX in-situ pour suivre l’evolution des phases de la zircone durant l’oxydation.

Acoustic emission has been successfully applied for monitoring a large variety of solids elaboration processes. In order to know the applicability of this technique in an industrial process such as grinding, mixing or also fluidized bed, we need to initially study the impacts of particles on different material surfaces. Namely, these will aim to simulate the industrial vessel walls. A wide range of powders and impact surfaces has been examined and the Hertz law has been applied to characterize the impact of particles. By considering only elastic deformations, the law has been simplified obtaining several parameters, such as the total displacement or the total load applied, which describe the impact. The influence on the acoustic emission of particle size and speed has also been explored in this study. A quasi-linear correlation has been found between these variables with a slope, which depends from material properties. Relevant differences have been observed within impact surfaces, especially in energy, caused by a different attenuation capacity in surface’s material. These differences are evident in waveforms obtained during experimental phase. Regarding other parameters such as amplitude a correlation has been found with elastic properties of particles and surfaces. In particular, sugar particles have produced higher amplitudes caused by plastic deformations. Finally, centroids frequencies have shown values completely different, allowing understanding the composition of the surface. In conclusion, surface’s properties influence frequency and energy fields, on the contrary particles elastic properties seem to affect amplitude values.

Experimental studies on flow loop allow estimating the amount of formed hydrate and their transport during time. The amount of hydrates formed spatially during flow is unknown together with the location of the beginning of sedimentation and plug. This experimental study was carried on to verify the use of acoustic emission (AE) to spatially follow the formation of hydrates but also sedimentation and agglomeration. The AE energy variations allowed to follow the emulsification, to identify the beginning of the crystallization and to follow the crystallization, agglomeration and plug/sedimentation in the flow loop.

Acoustic emission (AE), which has been successfully applied for monitoring a rather wide variety of solids elaboration processes, was almost never evaluated in the field of industrial crystallization for pharmaceutical or chemical products. Few papers reported that crystallization processes give rise to acoustic emission signals that could be related to the development of the basic crystallization phenomena. This study is intended to demonstrate new perspectives opened up by the possible use of acoustic emission (AE) as a non-intrusive and non destructive sensor for monitoring crystallization with a particular focus being put on real industrial processes. The preliminary results of the study will be reported in this work namely concerning the ability of the EA to follow the crystallization processes under different operating conditions and different types of crystallisation, and the obtained crystals in terms of particle size distribution and agglomeration degree.

Inorganic powder recycling should be a crucial process for the “smart factories” in the future. A complex three-phase system (bauxite mixed with ordinary Portland cement and water) with a new-coupled vibration-compaction device is studied. The compressive stress of compacts seems to be improved by using this device at low compaction pressure leaving the other characteristics unchanged. The tomographic study of macroscopic porosities shows differences in the pores repartitions inside vibrated and untreated compacts. Classic porosity repartition is shown in the classic compacted bauxite compacts whereas in the vibrated-compacted bauxite exhibits inhomogeneities. Despite this, we find these results quite promising for further investigations.

Acoustic emission (AE), which has been successfully applied for monitoring a rather wide variety of solids elaboration processes, was almost never evaluated in the field of industrial crystallization for pharmaceutical or chemical products. Few papers reported that crystallization processes give rise to acoustic emission signals that could be related to the development of the basic crystallization phenomena. This study is intended to demonstrate new perspectives opened up by the possible use of acoustic emission (AE) as a non-intrusive and non destructive sensor for monitoring crystallization with a particular focus being put on real industrial processes. The preliminary results of the study will be reported in this work namely concerning the ability of the EA to follow the crystallization processes under different operating conditions and different types of crystallisation, and the obtained crystals in terms of particle size distribution and agglomeration degree.

Zircaloy-4 oxidation behavior at high temperature (900 degrees C), which can be reached in case of severe accidental situations in nuclear pressurised water reactor, was studied using acoustic emission analysis coupled with thermogravimetry. Two different atmospheres were used to study the oxidation of Zircaloy-4: (a) helium and pure oxygen, (b) helium and oxygen combined with slight addition of air. The experiments with 20% of oxygen confirm the dependence on oxygen anions diffusion in the oxide scale. Under a mixture of oxygen and air in helium, an acceleration of the corrosion was observed due to the detrimental effect of nitrogen. The kinetic rate increased significantly after a kinetic transition (breakaway). This acceleration was accompanied by an acoustic emission activity. Most of the acoustic emission bursts were recorded after the kinetic transition (post-transition) or during the cooling of the sample. The characteristic features of the acoustic emission signals appear to be correlated with the different populations of cracks and their occurrence in the ZrO2 layer or in the alpha-Zr(O) layer. Acoustic events were recorded during the isothermal dwell time at high temperature under air. They were associated with large cracks in the zirconia porous layer. Acoustic events were also recorded during cooling after oxidation tests both under air or oxygen. For the latter, cracks were observed in the oxygen enriched zirconium metal phase and not in the dense zirconia layer after 5 h of oxidation. (C) 2015 Elsevier B.V. All rights reserved.

High temperature corrosion of metallic alloys causes significant damage on industrial pipes, tanks or reactors in the field of refining and petrochemical processes. Oxidation or carburization can create stresses in the corroded outer layer of the alloys; the relaxation of these stresses produces cracks followed by transient elastic waves. Different methods allow to record and analyze these transient elastic waves. In this study an innovative In situ equipment has been developed. Thermogravimetric analysis (TGA) has been coupled with an acoustic emission (EA) device to measure acoustic signals emitted during the corrosion process at high temperature. The sample mass variation was recorded simultaneously with the acoustic signals in order to understand the corrosion mechanisms. Piezoelectric sensors were fixed on the cold part of a symmetric thermogravimetric analyzer. An alumina waveguide used to transmit waves from the metal sample to sensors was specially designed based on several factors: internal diameter of the furnace, maximum acceptable weight for the balance, experimental atmosphere conditions, temperature. Moreover alumina best preserves the waveforms. The Hsu Nielsen test was applied to check the waveguide at room temperature. To check it at high temperature, a test based on the oxidation of a zirconium alloy which produces cracks in the oxide layer was developed and presented here. Zircaloy-4 oxidation behavior at high temperature (900°C), which can be reached in case of severe accidental situations in nuclear pressurized water reactor, was studied using acoustic emission analysis coupled with thermogravimetry. Two different atmospheres were used to study the oxidation of Zircaloy-4: a-helium and pure oxygen, b- helium and oxygen combined with slight addition of air. The mass gain rate curve under 20% of oxygen confirms the parabolic law due to oxygen diffusion in the inward oxide scale. Under a mixture of oxygen and air in helium, an acceleration of the corrosion was observed due to the detrimental effect of nitrogen. The kinetic rate increased significantly after a kinetic transition (breakaway). This acceleration was accompanied by an acoustic emission activity. Most of the acoustic emission bursts were recorded after the kinetic transition (post-transition) or during the cooling of the sample. The characteristic features of the acoustic emission signals clearly appear to be strongly correlated with the different populations of cracks and their occurrence in the ZrO 2 layer or in the α - Zr(O) layer. Acoustic events were recorded during the isothermal dwell time at high temperature under air. They were associated with large cracks in the zirconia porous layer. Acoustic events were also recorded during cooling after oxidation tests both under air or oxygen. For the latter, cracks were observed in the oxygen enriched zirconium metal phase and not in the dense zirconia layer after 5 hours of oxidation. Thermogravimetric experiments coupled with acoustic emission analysis are of interest in improving understanding of metallic material corrosion at high temperature. AE analysis is complementary for post-mortem oxidized sample characterizations. The AE technique has enabled detailed study of Zircaloy-4 oxidation behavior at high temperatures.