Foaming behaviour of primary, secondary and tertiary aqueous solution of amine for the removal of carbon dioxide

This study is focusing on the effect by the usage of different amine in order to remove acid gases that is foaming. Foam is made up of thousands of gas filled bubbles. Bubbles are formed when a liquid film encapsulates gas. This research is to investigate the foaming behaviour on the different cases for the primary (monoethanolamine, MEA), secondary (diethanolamine, DEA) and tertiary (methyldiethanolamine, MDEA) amine on the effect of concentration, temperature and impurities. Effect of all this parameters will be evaluated based on height of foam and collapse time of foam. Nitrogen gas (N2) will be used in this experiments as bubble gas. For this work several hypothesis has been set according to respectively cases. The hypothesis of this study is a higher solution concentration of MEA will reduce the foaminess. Other hypothesis is a higher solution temperature of MEA and DEA will reduce the foaminess also. Effects of impurities toward foaming formation are classified as following: iron sulphide, for MDEA solution foaming decrease; sodium chloride, for MDEA solution tendency for formation of foam decrease; methanol, foaming decrease in MDEA solution. It is apparently iron sulphide meet the most influential contaminants to the foam formation at the same concentrations of all impurities studie

Simultaneous mass transfer of H2S and CO2 with complex chemical reactions in an aqueous di-isopropanolamine solution = Gleichzeitige absorption von H2S und CO2 in Wässriger Di-isopropanolaminlösung \ud

The absorption of H2S and CO2 into an aqueous di-isopropanolamine (DIPA) solution was studied experimentally and theoretically as an example of simultaneous mass transfer with complex reversible reactions.\ud \ud The absorption phenomena were classified into three regimes: (1) negligible mutual interaction between the CO2 and H2S absorption, (2) intermediate interaction, and (3) extreme interaction leading to forced desorption of one of the gaseous components, while based on its overall driving force absorption would be expected. The key parameter largely determining the transitions between these regimes is the extent of depletion of the alkanolamine in the penetration zone.\ud \ud In order to study these phenomena, simultaneous absorption experiments were carried out in each of the three regimes mentioned above using a stirred cell reactor and for some experiments a wetted wall column.\ud \ud The experimental results were evaluated by means of a numerical solution of the penetration model description of simultaneous mass transfer with complex reactions (Cornelisse et al., Chem. Eng. Sci., 35 (1980) 1245). Recently we derived a numerical film theory description, which has also been incorporated in the evaluation. The measured hydrogen sulphide fluxes fall between film and penetration theory calculations, whereas the CO2 fluxes are closer to the film theory

Yttria stabilised zirconia (YSZ) membranes and their applications

1 Abstract The development of ceramic hollow-fibre membranes has gradually grown in the past decade. This specific geometry which has a high surface area per unit volume can dramatically increase the efficiency of separation processes and can be adapted to a variety of industrial applications. In addition, ceramic membranes are well known for their superior chemical and thermal stability which allows them to operate at high temperatures and/or in chemically harsh environments. Nevertheless, the main challenge for their industrial application is their insufficient mechanical strength. Yttria-stabilized zirconia (YSZ) is selected as a membrane material in this study. This is because the material has superior mechanical strength and it is relatively cheaper than other ceramic materials. The ionic conducting property of YSZ material is also a benefit when it is used in electrochemical applications. Porous and dense YSZ hollow-fibre membranes have been developed in the study using a combined phase inversion and sintering process. Different membrane morphologies, surface properties, mechanical strength and porosity could be achieved by controlling the YSZ content and sintering temperature. The developed YSZ hollow-fibre membranes with porous or dense structures show great potential for a variety of applications. Porous YSZ hollow-fibre membranes can be used as membrane contactors in aqueous media or for fluid separations in harsh environments, which most polymeric membranes cannot withstand. For the application of membrane contactors in aqueous media, the nature of the YSZ membranes must be modified from hydrophilic to hydrophobic in order to keep them non-wetted during the aqueous contacting processes. A robust and hydrophobic YSZ hollow-fibre membrane was developed by introducing a pretreatment technique, followed by a grafting procedure. The hydrophobic YSZ membrane was found to be thermally stable up to 270 °C and chemically stable in hexane for 100 h. This membrane was then applied to the absorption of carbon dioxide from a high concentration aqueous ethanolamine solution. The results demonstrated the high efficiency of the ceramic hollow-fibre membrane contactor compared to traditional devices. Dense YSZ hollow-fibre membranes with outer diameters of 1.28 mm have been used as an electrolyte support in a solid oxide fuel cell. The YSZ electrolyte-supported SOFC was prepared at relatively lower sintering temperatures and shorter sintering durations. The YSZ-based hollow fibre SOFC demonstrated its ionic stability in a redox environment and mechanical stability at temperatures up to 800 °C. The results also demonstrated its electrochemical performance at high temperature. In summary, this thesis focuses on the development of YSZ hollow-fibre membranes from the initial step of fabricating the membrane to the final step of their potential application. Different structures of YSZ hollow-fibre membranes were studied, discussed and their potential performance was compared to the achievements of others in order to gain more understanding and information on the use of the membranes for practical applications

Electrowetting: from basics to applications

Electrowetting has become one of the most widely used tools for manipulating tiny amounts of liquids on surfaces. Applications range from 'lab-on-a-chip' devices to adjustable lenses and new kinds of electronic displays. In the present article, we review the recent progress in this rapidly growing field including both fundamental and applied aspects. We compare the various approaches used to derive the basic electrowetting equation, which has been shown to be very reliable as long as the applied voltage is not too high. We discuss in detail the origin of the electrostatic forces that induce both contact angle reduction and the motion of entire droplets. We examine the limitations of the electrowetting equation and present a variety of recent extensions to the theory that account for distortions of the liquid surface due to local electric fields, for the finite penetration depth of electric fields into the liquid, as well as for finite conductivity effects in the presence of AC voltage. The most prominent failure of the electrowetting equation, namely the saturation of the contact angle at high voltage, is discussed in a separate section. Recent work in this direction indicates that a variety of distinct physical effects¿rather than a unique one¿are responsible for the saturation phenomenon, depending on experimental details. In the presence of suitable electrode patterns or topographic structures on the substrate surface, variations of the contact angle can give rise not only to continuous changes of the droplet shape, but also to discontinuous morphological transitions between distinct liquid morphologies. The dynamics of electrowetting are discussed briefly. Finally, we give an overview of recent work aimed at commercial applications, in particular in the fields of adjustable lenses, display technology, fibre optics, and biotechnology-related microfluidic devices

Rate-based Approaches for the Carbon Capture with Aqueous Ammonia Without Salt Precipitation

The aim of this paper is the evaluation of the influence of the kinetic of the NH3-CO2-H2O reactions in the absorber with respect to the electric power losses due to the steam bleeding from the turbine for the regeneration of the solvent. The results exposed conclude that there are few works about the kinetic of the aqueous reaction of the system NH3-CO2-H2O and data from the literature are not in agreement among them probably due to a dependence of the kinetic constants on the ammonia concentration in the liquid. The kinetic parameters have a strong influence on the specific electric power losses

Hydrodynamics in a cocurrent gas-liquid trickle bed at elevated pressures

Data on design and operation of trickle beds at elevated pressures are scarce. In this study the influence of the gas density on the liquid holdup, the pressure drop, and the transition between trickle and pulse flow has been investigated in a tricklebed reactor operating up to 7.5 MPa and with nitrogen or helium as the gas phase. Gas-liquid interfacial areas have been determined up to 5.0 MPa by means of CO2 absorption from CO2/N2 gas mixtures into amine solutions. \ud A comparison of the results from nitrogen as the gas phase to those of helium shows that at equal gas densities the hydrodynamic states are the same. The gas-liquid interfacial area increases when operating at higher gas densities. When the determined dimensionless interfacial areas agl/as are all within the range 0.25-0.8, the trickle-bed reactor is suggested to operate in the trickle-flow regime. The gas density has a strong influence on the liquid holdup. Due to the higher pressure gradients at elevated gas densities, the liquid holdup decreases noticeably. Besides, the boundary between the trickle-flow and pulse-flow regime shifts toward higher liquid throughputs: the region for trickle-flow operationg becomes larger. For the liquid holdup and the pressure gradient in the trickle-flow regime, correlations derived based on dimensionless numbers can be applied to high-prssure trickle beds

Mass transfer in gas-liquid slurry reactors

A critical review is presented on the mass transfer characteristics of gas¿liquid slurry reactors. The recent findings on the influence of the presence of solid particles on the following mass transfer parameters in slurry reactors are discussed: volumetric gas¿liquid mass transfer coefficients (kLa, kGa), liquid-side mass transfer coefficients (kL and kS) and specific gas¿slurry contact area (a). The second part of this paper reviews the recent progress in our knowledge and understanding of the enhancement of gas¿slurry mass transfer due to the presence of solids. Five different cases are distinguished, i.e. \ud \ud ¿ enhanced mass transfer by physical adsorption on small particles.\ud \ud ¿ enhanced mass transfer by fast homogeneous reactions in the slurry, due to inert particles,\ud \ud ¿ enhanced mass transfer by homogenous reaction in the liquid with dissolving particles,\ud \ud ¿ enhanced mass transfer due to reactive particles and\ud \ud ¿ enhanced mass transfer due to catalytic particles in heterogeneous reactive systems.\ud \ud Prospective areas for additional research are identified

CO<inf>2</inf> absorption using diethanolamine-water solutions in a rotating spiral contactor

Results for mass transfer in a rotating spiral device are presented here for absorption of carbon dioxide from nitrogen carrier gas using mixtures of diethanolamine (DEA) and water. The ability of the device to examine the full range of flow rate ratio for the two phases while controlling the relative thicknesses of the phase layers is applied to surveying absorption performance over a wide range of DEA concentration at 312 K and 1.8 bara. Comparisons are made for a fixed 86 μm liquid layer thickness, which is shown to fix also the fraction of the liquid accessible by diffusion, while maintaining 90% removal of CO2 from a gas stream of 10% (mole) CO2 in nitrogen. The increasing liquid viscosity with DEA fraction is countered by reducing the liquid flow rate to maintain constant liquid layer thickness and diffusion depth. The allowed gas throughput, while meeting 90% removal, increases with DEA concentration until the increasing viscosity gives sufficient reduction in liquid flow rate to offset the increasing CO2 capacity of the liquid. The maximum gas flow rate has a broad peak centred at a DEA mole fraction of about 0.072 (31% by mass). Utilisation of the amine is increased as DEA concentration increases, apparently as a result of the longer residence time, suggesting an effect of chemical time scales on the order of seconds. For a fixed concentration, full utilisation of the amine is achieved by decreasing the liquid flow rate, which reduces layer thickness and increases diffusion time. The work highlights the use of the rotating spiral for rapid and accurate testing to determine optimum liquid composition of absorbent formulations