Cyclopentane hydrates – A candidate for desalination?

International audienceThis article presents a systematic review on the past developments of Hydrate-Based Desalination process using Cyclopentane as hydrate guest. This is the first review that covers all required fundamental data, such as multiphase equilibria data, kinetics, morphology, or physical properties of cyclopentane hydrates, in order to develop an effective and sustainable desalination process. Furthermore, this state-of-the-art describes research and commercialization perspectives. When compared to traditional applications, cyclopentane hydrate-based desalination process could be a promising solution. Indeed, it operates under normal atmospheric pressure, lower operation energies are required, etc… However, there are some challenges yet to overcome. A decision aid in the form of a diagram is proposed for a new cyclopentane hydrates-based desalination process. Hopefully, concepts reviewed in this study will suggest new ideas to advance technical solutions in order to make commercial hydrate-based desalination processes a reality

Thermodynamics of cyclopentane hydrates formation from brine: experimental and modelling study

International audienceCyclopentane hydrates-based salt-removal has been considered to be one promising technologies for desalination because it requires a low amount of operating compared to traditional methods such as thermal distillation, membrane separation, or freezing. In order to design a desalination, or water treatment, plant, it is necessary to understand both the thermodynamics of crystallization of hydrates (CPH) in presence of salt, and the kinetics. Therefore, this study aims to determine and model the equilibria of cyclopentane hydrates in the presence of electrolytes. Eight salt mixtures have been considered: NaCl, KCl, NaCl-KCl, CaCl2, Na2SO4, MgCl2, MgCl2-NaCl, MgCl2-NaCl-KCl, with a wide range of concentrations. Two successive experimental procedures, quick and slow, have been applied to determine equilibrium temperatures. The objective of the quick procedure is to provide an initial estimate of the equilibrium temperature. Then, the slow procedure is used to obtain more accurate data. Experimental results show that equilibrium temperatures dropped significantly with an increase in salt concentration, whatever the kinds of salt. In comparison with the literature, the final slow procedure in pure water provides, or with NaCl, provide results very close to studies of Kishimoto et al. [2] and Zylyftari et al. [3], obtained either by slow dissociation or micro Differential Scanning Calorimetry (&#0181-DSC). Moreover, salt co-precipitation can be achieved simultaneously with the cyclopentane hydrate formation. For instance, the eutectic point of four phase equilibrium of {liquid water + liquid CP + CPH + Na2SO4.10H2O} has been obtained in this study. This provides possibility for by-products, or value added products, recovery thanks to CPH. Afterward, four thermodynamic approaches have been considered for the results modelling. One is based on Standard Freezing Point Depression method. Another one considers the very new Hu-Lee-Sum (HLS) correlation, designed to predict the suppression temperature of clathrate hydrates when an additive is introduced into the system. The two last models are based on van der Waals and Platteeuw model, using either Kihara potential, or a correlation instead (ABOC).All models provide data with a difference lower than 0.7°C compared to experimental results. However, the best method is the ABOC method (activity based occupancy correlation). This approach uses a correlation between the clathrate occupancy, and the water activity. It furnishes equilibrium temperatures within 0.2°C uncertainty

Equilibres thermodynamiques des hydrates de cyclopentane en présence de sels pour la purification de l’eau: données expérimentales et modélisation

Thème: Aspects fondamentaux de la cristallisation et de la précipitationNational audienc

Experimental Study and Modelling of Cyclopentane Hydrates in the presence of NaCl, KCl and a mixture of NaCl -KCl

Sessions : Gas Hydrate FundamentalsInternational audienceResults from an experimental study of cyclopentane hydrate in the presence of NaCl (0 –23% t), KCl (0 -20% wt) and an equi-massmixture of NaCl-KCl (0 -22% wt) following a quick and a slow dissociation procedures are reported. The results show that the equilibrium temperatures of cyclopentane hydrate dropped significantly with an increase in salt concentration . A temperature shift between the equilibrium temperatures following the quick and the slow procedure was also observed.Two thermodynamic approaches are then presented to predict the equilibrium temperatures. The predicted-equilibrium temperatures are in good agreement with the experimental ones

Modeling of Air –Water Flow in a Rock&Roll Flow Loop

Congrès en distanciel, visio-conférenceNational audienceGas-liquid flow dynamics in pipes is a complex phenomenon encountered in many industrial spheres. Particularly, in petroleum production and transportation the design of the facilities, safety, and efficiency of the industrial operations strongly depend on accurate prediction of flow behavior. Since the seventies, two-phase flow models and correlations predicting the liquid holdup and pressure drop, have been actively developed. However, there are still mismatches between model predictions and experimental results. These discrepancies may be attributed to the benchtop limitations in length, complexity of the gas-liquid interface, and accuracy of empirical correlations used within a model

Air - Water Flow in a Rock&Roll Ring Flow Loop: Visualization and Modeling

Session 2: Crystallisation and flow modelling - Prix du meilleur poster du congrès ECGH 2022International audienceUnderstanding the interdependence between flow morphology and hydrate formation is essential for the safe and efficient transport of multiphase flow systems along pipelines. This work is an initial milestone in the development of experimental and analytical tools for studying the formation and flow of gas hydrates in curved pipes. The scientific problem underlying this effort is whether the methodologies used to solve the horizontal multiphase flow can be extended to the present geometry

Multiphase flow in the Rock&Roll Ring-Flowloop

En cette année 2020 un peu particulière, la journée scientifique s'est tenu sous la forme d’un webinaire organisé par le site clermontois représenté par l’Institut Pascal (IP).National audienceThe aim of this work is to conduct an experimental study on gas-liquid flow patterns in an in-house made Ring flowloop called Rock&Roll. The Rock&Roll flowloop is a unique apparatus the pipe is installed on a disk that is sequentially inclined by an axis in 4 positions, to induce the motion of the fluid, inside the ring-tube, similarly to a rocking cell. Two parameters drive the torus: the inclination angle and the rotation speed. The absence of pump enables undisturbed flow, while the endless test section affords flow to become fully developed. The first experimental investigations enabled to establish the experimental protocol and study the air-water two-phase flow patterns in the torus by varying liquid loading, diameter of the tube and rotation speed of the torus. On the base of qualitative observations, a flow regime map was produced

Behavior of cyclopentane hydrates formation and dissociation in pure water and in the presence of sodium chloride

Session: International Conference on Integrated Petroleum Engineering (IPE)International audienceThis paper reports the temperature and conductivity behaviors of the cyclopentane hydrate formation and dissociation with and without sodium chloride. The experiments were all performed in a jacketed vessel connected to a chiller having the operating temperature down to -20 °C. The equilibrium temperatures of cyclopentane hydrate were determined in the presence of sodium chloride solution with concentration from 0% to 26% in mass fraction (the saturated concentration of NaCl at 20 oC) according to an environmental dissociation method. The results showed that the temperature of mixture inside the vessel increased when cyclopentane hydrates formed due to the exothermic nature property of the crystallization. The slope of the temperature curve decreased when cyclopentane hydrates dissociated intensely resulting from its endothermic characteristic. The conductivity of mixture had illogical tendencies owing to the appearance of air bubbles and hydrate solid phase during crystallization and dissociation. The results also showed that the equilibrium temperatures of cyclopentane hydrate range from 7.7 °C down to -13.2 °C, and are inversely proportional to the salt concentration

Mécanismes de cristallisation et vitesse de croissance d’hydrates de cyclopentane en présence de sels

Thème: Aspects fondamentaux de la cristallisation et de la précipitationNational audienc

Crystallization Mechanisms and Rates of Cyclopentane Hydrates Formation in Brine

International audienceClathrate hydrates most often grow at the interface between liquid water and another fluid phase (hydrocarbon) acting as a provider for the hydrate guest molecules, and some transfer through this shell is required for the hydrate growth to proceed, thus self-limiting the reaction rate. An optical microscope and a horizontal reaction cell are utilized to capture the shell growth phenomenology and to estimate the hydrate layer growth rates from sequential pictures. Cyclopentane (CP) is chosen as the hydrate-forming molecule to obtain hydrates at low pressure. Experimental hydrate layer growth rates are provided for the CP + brine system, using various combinations of salts and various degrees of subcooling