In this paper, an optical technique based on fluorescence intensity is applied and calibrated to simultaneously measure film thickness (up to 8 mm) and interfacial velocity of the liquid film flow. Thus, thin-film flows at intermediate and low Reynolds number (13 < Re < 290) are experimentally studied with special attention given to the spatial variation, the frequency of the waves, and interfacial liquid velocity associated with global visual observation. Two fluids (water-ethanol mixture) characterized by low surface tension (a = 35 and 50 mN/m) and three fluids (water-glycerin mixture) with high viscosity (mu = 5, 10, and 15 mPa.s) are used to investigate the influence of physico-chemical properties on thin-film flow on flat and corrugated plate topologies. First, the effect of physico-chemical properties on the global variation of waves shape and instability evolution has been investigated. Different work fluids were used in the same experimental conditions on a flat plate. Results showed that decreasing surface tension has a stabilizing effect on the flow, dampening the capillary waves that should otherwise arise. At high viscosity, solitary waves with high thickness followed by an undisturbed thin-film with a constant thickness appear. The impact of liquid flow rate and inclination (0 = 10 degrees and 20 degrees) was also studied. It shows that at higher inclination the film thickness decreases and then increases as the liquid flow rate increases. Next, the impact of counter-current gas was studied and we demonstrated that the amplitude of the main waves significantly increases even at low gas velocity while the effect on the velocity of the wave starts to be significant at a counter-current gas velocity of 3 - 4 m/s. Finally, the effect of the corrugation of the solid plate at a high inclination angle (0 = 60 degrees) shows the onset of the breaking waves phenomenon, especially for fluids with low surface tension.

The RSP200X, as one of the latest generation of Raschig’s structured packings (Raschig Super-Pak, RSP), has been investigated for use in scrubbing columns operating at high liquid loads where it could be particularly well adapted. These RSP packings offer a good potential for increasing capacity while maintaining mass transfer efficiencies at high levels. IFPEN has measured hydraulic and mass transfer performances in two columns of different diameters (146mm and 1000mm). Flooding limits were in agreement with literature, however at high liquid loads and for the tested X-Style RSP they were 30–40% lower than those calculated with the Winsorp Software delivered by Raschig. With the support of the present results a modified version of Winsorp has been elaborated for high liquid loads and X-Style RSP. In terms of mass transfer, the CO2/MDEA system was used to measure kLae while the classic CO2/NaOH and SO2/NaOH systems were used for ae and kGae measurements. The RSP200X was found to develop a high interfacial area compared to its geometric area. While for standard packings the gas flow rate is often considered to have only a small effect on effective area when operating below the loading point, its effect measured on RSP200X is significant and of the same order as for liquid load. Measurements of kLa and kGa further confirm these trends.

Wall wipers are commonly used in columns filled with structured packings in order to reduce the liquid flow along the column walls. In small diameter columns wall regions are prominent and wall flow, if not well tended to, can adversely affect measured mass transfer parameters, particularly the liquid side mass transfer coefficient kLae. Wire gauze wall wipers provided by some manufacturers do not properly prevent wall liquid flow. In this work, specific wall wipers designed to re-direct liquid wall flow onto packing surfaces were tested against standard wall wipers that do not always properly reduce wall flow. Tests were run on two distinct facilities each with a column diameter of about 150 mm and with bed heights from 0.42 to 1.68 m of Mellapak™ 250.Y packing. The results demonstrate that with the more effective wall wipers it is possible to measure intrinsic height independent values of kLae that match those obtained in a 300 mm diameter column with standard wall wipers.

Wall wipers are commonly used in columns filled with structured packings in order to reduce the liquid flow along the column walls. In small diameter columns wall regions are prominent and wall flow, if not well tended to, can adversely affect measured mass transfer parameters, particularly the liquid side mass transfer coefficient kLae. Wire gauze wall wipers provided by some manufacturers do not properly prevent wall liquid flow. In this work, specific wall wipers designed to re-direct liquid wall flow onto packing surfaces were tested against standard wall wipers that do not always properly reduce wall flow. Tests were run on two distinct facilities each with a column diameter of about 150 mm and with bed heights from 0.42 to 1.68 m of Mellapak™ 250.Y packing. The results demonstrate that with the more effective wall wipers it is possible to measure intrinsic height independent values of kLae that match those obtained in a 300 mm diameter column with standard wall wipers.

A commonly used class of methods for the numerical simulation of two-phase flows is level set. It is often reported though that this method does not accurately conserve mass of each fluid, unlike other interface capturing techniques such as volume-of-fluid. A further concern besides mass conservation is the formation of any parasitic currents. Since the initial formulation of level-set methods, however, numerous modifications have been proposed, and it does not seem clear whether mass conservation errors and parasitic currents are problematic for all of these and, if not, what key steps could be taken to avoid them. Furthermore, results reported in the literature are often for benchmark tests in two dimensions, and it is not clear whether a good performance there holds up in three dimensions. We undertake here a comparative study, reporting test results in two and three dimensions for various level-set methods on a variety of problems. Kinematical tests are first performed for prescribed velocity fields, followed by benchmark tests including the solution of the Navier–Stokes equations. It is shown that higher-order schemes for spatial and temporal discretization may improve mass conservation and avoid interface distortion. In particular, two reinitialization methods that are straightforward to implement perform very well at all these tests. It is demonstrated that some schemes introduce parasitic oscillations in the simulation of Rayleigh–Taylor instability.

A new method is presented to perform three-dimensional simulations of two-phase flows with moving contact lines using level-set. To account for the full range of length scales involved in the physical problem under realistic conditions, without having to resolve the flow down to the smallest continuum scale, a dynamic contact angle model based on asymptotic theory is used in conjunction with the computational method. Contact-angle hysteresis is also represented in this methodology. The method is validated against simulations wherein the flow is fully resolved over all length scales, and experiments of spreading droplets and droplets sliding down an inclined substrate.

Methods for the determination of mass‐transfer coefficients and effective interfacial areas in packed absorption columns are reviewed. For each parameter, the methods are grouped into categories on the basis of their physical principle; the chemical systems used, experimental protocol, and the advantages and inconveniences are discussed. The treatment of end effects, the influence of packed bed height, and the recent efforts in standardization of measurement methods are also treated. The aim of the review is to give a broad overview of the methods used in literature in the last eight decades, some of which might be reconsidered in the light of modern measurement techniques and to evaluate them in relation to precision, practicality and hazardousness thereby to facilitate the search for reliable, precise, and convenient experimental practices. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3246–3275, 2017

Abstract The objective of this paper is to present new improvements in the knowledge of the performance of an Acid Gas Removal Unit (AGRU) installed on a floating gas production facility, thanks to a R&D program testing the influence of 3D motions and accelerations. The accurate design of the Acid Gas Removal Unit has a great importance for the profitability and success of a FLNG project. In order to limit both weight and footprint, it shall rely on the lowest possible solvent flowrate and on the minimal and optimum equipment size to treat the feed gas while taking into account motions of the floating support. The proposed paper will demonstrate how a tight but safe design of an amine unit can be proposed thanks to the results of an extensive experimental program. Total, Prosernat and IFPEN have conducted a four-year R&D program at Heriot-Watt University based on pilot tests aiming at modelization of mass transfer and hydraulics of tilting and moving towers. This program has included the testing of multiple parameters such as liquid/gas flowrates, liquid viscosity, diameter of towers, height of packing beds, packing efficiency. This has been done under various conditions: static tilt, pitch and 3D motions generated by a hexapod robot with six degrees of freedom. The motion conditions tested were similar to those experienced by a column installed on a floating gas production support or on a FLNG. The collected information on hydraulics and mass transfer showed a significant impact of motions on liquid and gas distribution along the packing beds that can, under conditions of loads of gas and liquids, lead to a significant loss of absorption performances. An in-depth analysis of the large experimental data set with a comprehensive understanding of the phenomena in place allowed the development team to propose a robust model. This model is now embedded in a rated base mass transfer proprietary simulator of AGRU that can predict with good accuracy the impact of motions of the floating support on the performance of the unit. This paper will present key results accumulated along the program about the impact of motions on liquid/gas maldistribution along a packing bed. It will explain how the accumulated knowledge enables to size tight but reliable AGRU's for installation on a floating support, in the presence of CO2, but also of other contaminants like H2S. The discussion will be supported by comprehensive examples of degradation of the absorption performances on real cases affected by sea motion.

distributor tray exchange column (1) heat and / or matter between a gas and a liquid including at least one partition (6) defining compartments (8, 9) on the upper face of said tray (2) , said partition (6) perforations to allow circulation of a portion of the liquid between said compartments (8, 9), wherein said tray includes at least one compartment of distribution (8) comprising at least one means for liquid passage (5, 11) through said tray (2) and at least one means for gas passage (4) through said tray (2), wherein said tray includes at least one retaining compartment (9) at the periphery of said tray (2) includes no means for the passage of liquid through said tray.

A dynamic contact angle model is developed with a level-set method to simulate three-dimensional macroscopic flows with moving contact lines. The code has been validated against Direct Numerical Simulations (DNS) and experimental results of droplet spreading in viscous and inertial regimes. The code allows simulating three-dimensional flows with moving contact lines taking into account contact angle hysteresis.

Post-combustion capture processes using amines are considered as one of the preferred options for CO2 Capture and Storage (CCS). However, the cost of avoided CO2 is very large and must be reduced. The latter cost is strongly linked with column designs which consequently must be optimized. In the present article, hydrodynamics and mass transfer performances of random and structured packings are discussed in terms of pressure drop, capacity and most importantly in terms of mass transfer parameters, in particular in terms of interfacial area which is the most important parameter for CO2 absorbers design. Comparison of different commercial high efficiency packings is discussed from experimental characterization and from CFD simulations and a methodology for future developments is proposed.

Interfacial effective area and liquid hold-up in structured packing geometries are investigated using the volume of fluid method. Three-dimensional numerical simulations of gas-liquid flow on inclined plane plate and in a structured packing are performed. The VOF method is used to capture the gas-liquid interface motion. After a first validation case on the wetting phenomena prediction on an inclined plane plate, the effective interfacial area, the liquid holdup and the degree of wetting of packing are studied as function of liquid flow rate and wall surface characteristic (adherence contact angle). Results show that the liquid flow-rate and the contact angle play a significant role. It is found that the interfacial effective area and the degree of wetting of packing increase as the liquid flow rate increases and as the contact angle decreases. Moreover, under the influence of the contact angle, different liquid film shapes are observed. The simulations results are compared to experimental data available in literature. This work shows that the CFD is a powerful tool to investigate performance characteristics of structured packings. Moreover, this work shows how CFD can be used as an effective tool to provide information on fluid flow behavior and determination of interfacial area, liquid hold-up and minimum flow-rate to ensure complete wetting. These parameters could be further used in process simulation at larger scale for the development and the design of efficient packings. (C) 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

To conquer the current FLNG challenge, experts have to answer the question " What effect does the movement of the ship have on the amine process?". It is necessary to rely on accurate knowledge of the impact of the floating support movement on the towers operation, to first secure then optimize the design of the process units. Indeed both flooding and internals efficiency will significantly impact the towers sizing (diameter and height) and thus the whole FLNG project. It is a complex problem to be able to take into account the multitude of factors such as liquid viscosity, height of packing, diameter of column, acceleration, liquid/gas flowrate, type of packing, and motions imposed on the system. After first years of work when they completed an extensive review of bibliographic data to build an early model of maldistribution based on a theoretical approach, Total, Prosernat and IFPEN have now performed more than one year research and development at Heriot-Watt University to model mass transfer and hydraulics of a tilting, moving tower. To assess the impact of experimental column diameter and to be in position to scale-up the results, two columns have been used and will be described. The program has included both static and motion tests with varying periods and angles, at different liquid loads to map the distortion of liquid distribution at adjustable heights of packing. The data now acquired has shown, depending on operating conditions, a significant impact on liquid distribution in the packing bed, leading to differentiated wetted zones, including dry and overloaded areas. Some examples will be given to illustrate the impact on tower efficiency and the corresponding tower oversizing based on the results of test campaign.

An electrolyte equation of state based on Redlich Kwong Soave EOS is applied to the representation of the equilibrium properties of the water-CO2-diethanolamine system in the 298-366.5 K temperature range. In this work we have developed a model which is able to represent the liquid phase speciation as well as the CO2 solubility in the amine solutions. For this purpose the database used for the parameters determination consists of solubility data as well as Henry's constants and speciation data including experimental concentrations of molecular CO2 and of carbamate. The need of such speciation data is shown by a comparison of the speciation results obtained and those predicted using models from the literature based only on the data treatment of experimental VLE values. (C) 2013 Elsevier B.V. All rights reserved.