Triethylene Glycol Solution Research Articles

Effect of operating variables on isopropanol absorbed by triethylene glycol solution and discussions on the mass transfer coefficient predicted by artificial neural network

The mass transfer performance of isopropanol (IPA) absorption by triethylene glycol (TEG) aqueous solution in a spray-bed absorber was investigated, and the mass transfer coefficients predicted by an artificial neural network (ANN) and response surface methodology were compared in this study. The operating variables affecting the mass transfer performance of a spray-bed absorber include the gas and TEG fluxes, concentration of IPA, concentration of TEG aqueous solution, and operating temperature. The experimental results demonstrated that the mass transfer coefficient of a spray-bed absorber increased with increases in gas and liquid fluxes and decreased with increases in concentration of IPA. The Back-Propagation algorithm in the ANN model was selected to predict the mass transfer coefficients of the spray–bed absorption system. Hidden layers with 2, 4 and 6 neurons respectively were set to analyze the effect of the number of neurons on the target value, and then different transfer functions were used to compare the accuracy in predicting mass transfer coefficient. Finally, the influences of the number of hidden layers and different learning rules on the prediction of mass transfer coefficients were examined. The simulated results showed that the average error of the ANN using the TanhAxon transfer function, the Conjugate Gradient learning rule, two hidden layers, and 6 neurons in each hidden layer was within 1%. The results not only verified the successful establishment of the experimental device but also proved the accurate prediction of mass transfer coefficients by the ANN model.

Electropolishing of Magnesium and Its Alloys using a Safe Glycol Solution containing Sodium Chloride

Abstract The electropolishing behavior of pure magnesium and its alloys in ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TrEG), and tetraethylene glycol (TeEG) solutions containing sodium chloride was investigated using electrochemical measurements, microscopic observations, and reflectance measurements. Large light-grayish cloudy areas with micrometer-scale linear irregularities were formed on the magnesium surface via constant-voltage electrolysis in the EG solution, whereas mirror-finished magnesium surfaces were successfully obtained in the DEG and TeEG solutions. Among these, the DEG solution is considered appropriate for electropolishing because of its lower viscosity and market price. The reflectance of the entire visible wavelength region gradually increased with time during electrolysis in the DEG solution at 308 K. We found that short-term electrolysis for 3 min at the higher voltage of 75 V should be selected if a moderately polished surface is to be rapidly obtained, whereas long-term electrolysis for 60-300 min at 50 V should be performed if a highly polished surface with an extremely high reflectivity measuring more than 80% can be obtained. Three-dimensional magnesium specimens with curved and spiral shapes and an LZ91 magnesium alloy consisting of a simple solid-solution matrix can also be electropolished via electrolysis in a DEG solution.

Reversible phase transformations between Pb nanocrystals and a viscous liquid-like phase.

Phase transformations have been a prominent topic of study for both fundamental and applied science. Solid-liquid reaction-induced phase transformations can be hard to characterize, and the transformation mechanisms are often not fully understood. Here, we report reversible phase transformations between a metal (Pb) nanocrystal and a viscous liquid-like phase unveiled by in situ liquid cell transmission electron microscopy. The reversible phase transformations are obtained by modulating the electron current density (between 1000 and 3000 electrons Å-2 s-1). The metal-organic viscous liquid-like phase exhibits short-range ordering with a preferred Pb-Pb distance of 0.5 nm. Assisted by density functional theory and molecular dynamics calculations, we show that the viscous liquid-like phase results from the reactions of Pb with the CH3O fragments from the triethylene glycol solution under electron beam irradiation. Such reversible phase transformations may find broad implementations.

Multicomponent vapor-liquid equilibrium measurements and modeling of triethylene glycol, water, and natural gas mixtures at 6.0, 9.0 and 12.5 MPa

Triethylene glycol (TEG) is commonly used for natural gas dehydration, and with subsea processing facilities on the rise, an increasing interest is being shown in complex phase equilibria involving petroleum fluids and polar compounds. In this study, examples of such phase equilibria have been studied. New measurements for multicomponent vapor-liquid equilibrium (VLE) of TEG/Water/Natural Gas systems have been performed at pressures ranging from 6.0 MPa to 12.5 MPa and temperatures in the range 15 °C to 40 °C. Two types of natural gas, a Synthetic Gas (xCH4=0.62) and a Real Gas (xCH4=0.92), were mixed with an aqueous TEG solution, with TEG weight percentages ranging from 95 wt.% to 99 wt.%. Glycol in gas (y1), water in gas (y2), and gas solubility in liquid (xNG) were measured with relative experimental uncertainties below 32%. Since the systems are highly associating, the Cubic-Plus-Association (CPA) equation of state (EoS) was selected to model their phase behavior . Different association schemes (4C, 4F, 5F, 6F and 5C) were tested for TEG, and the classical 4C scheme is shown to perform best. The CPA EoS performed in general terms well, considering the number of components in the systems, the associated complexities, and high measurement uncertainty for such low concentrations (<1 ppm) in the gas phase. Furthermore, the content of N2, CO2, CH4 and ethane were modelled in the liquid phase at various conditions.

Optimization of operating conditions for energy conservation in a packed-bed absorber

Indoor humidity can be adjusted by an absorption air conditioning system; however, reaching zero humidity is not absolutely the purpose of such adjustment. Therefore, one of the purposes of this study was to discuss the suitable operating conditions in the packed-bed absorber under conformable environments. Triethylene glycol (TEG) solution was used in this study to remove water vapor from air in a packed-bed absorber. The JMP software was adopted to run the response surface methodology, and the methodology was used to determine the operating conditions in a packed-bed absorber. Both experimental and statistical results demonstrated that the amount of water vapor removed by the packed-bed absorber increased with increases in the gas/liquid flow rates and TEG concentration. Analysis with the response surface methodology suggested that the liquid flow rate should be 0.013 to 0.015 kg/s and that the gas flow rate should be 0.022 to 0.025 kg/s to achieve 65% to 80% flooding. The suggested concentration of TEG solution is 70.65 to 85 wt.% due to the lower absorption performance below 70.65 wt.% and the larger energy consumption beyond 85 wt.%. With this range, not only is the amount of water vapor removed acceptable, but the requirement of energy-saving is met. The average error between experimental and predicted removal amounts is about 3.6%. The statistical method is recommended to obtain the mass transfer correlation for mass transfer devices in various operating conditions and the mass transfer amount can be predicted by the absorber designer.

Effects of Vapor Pressure of Desiccant Solution on Mass Transfer Performance for a Spray-Bed Absorber

The depression in vapor pressure caused by adding desiccant to liquid water can be regarded as the driving force for the dehumidification process. The vapor pressure depends on the temperature and the concentration. Therefore, the purpose in this study is to discuss the mass transfer performance affected by operating variables and to show that the vapor pressure is a key factor affecting the mass transfer performance for absorbing water vapor by triethylene glycol (TEG) solution. The experimental results showed that the mass transfer coefficients were decreased with increases in the temperature and increased with increases in the concentration, respectively, while the mass transfer coefficients were increased with increases in the vapor pressure depression. Although both the average error is within 5% among the mass transfer correlation involving the vapor pressure and that involving the temperature and the concentration in predicting the mass transfer coefficient, there are just two terms, those are vapor pressure and fluid flow rate, associated with operating variables used in the mass transfer correlation. The depression in vapor pressure was not only proved to be the driving force for absorbing water vapor by a desiccant solution, but also a key factor affecting the mass transfer performance.

Enhanced Regeneration of Triethylene Glycol Solution by Rotating Packed Bed for Offshore Natural Gas Dehydration Process: Experimental and Modeling Study

To address the problems of confined space for offshore application, rotating packed bed (RPB) was firstly used to enhance the regeneration of TEG solution in natural gas dehydration process. The performance of the regeneration, which was exhibited in terms of the desorption efficiency and mass transfer coefficient, was investigated experimentally. The effects of various operating parameters, including rotation speed, gas-liquid ratio, liquid flow rate, liquid inlet temperature, and inlet concentration of rich TEG were studied to assess the impacts on the regeneration process. It was found that the purity of regenerated TEG solution by RPB was basically above 99.7% under a common gas-liquid ratio of 45 (volume ratio), and even higher than 99.98% under the optimal conditions. A mass transfer model combined two-film theory and penetration theory was established, which could well predict the TEG solution regeneration performance in RPB. According to the established model and ASPEN simulation result, an RPB and a packed column were designed respectively for a specific TEG regeneration task. It was found the volume reduction factor of RPB was about 8, which showed well adaptation of RPB for the offshore natural gas extraction due to the outstanding mass transfer performance in the TEG regeneration process.

Prediction of equilibrium conditions for gas hydrates in the organic inhibitor aqueous solutions using a thermodynamic consistency-based model

Considering organic inhibitor plays a great role in preventing hydrate formation in oil and gas industry by shifting the hydrate phase equilibrium conditions, it is necessary to study the effects of organic inhibitors on the phase behavior of gas hydrates. In this study, a thermodynamic consistency-based model was developed to predict the phase equilibria of gas hydrates in methanol (MeOH), ethanol (EtOH), monoethylene glycol (MEG), diethylene glycol (DEG), triethylene glycol (TEG) and glycerol (GLY) solutions with concentrations of 5.44 wt%~ 65 wt%, respectively. The Chen-Guo model was applied to hydrate system. Compared with the original Hu-Lee-Sum correlation, a modified HLS type correlation that additionally considers the slight effect of temperature on calculating the activity of water was proposed. The prediction accuracy was characterized by the average absolute deviation in temperature (AADT). Results show that for CH4 hydrate the Chen-Guo model coupled with HLS correlation performs as good as the original HLS correlation and PVTSim. The corresponding AADT for each organic inhibitor can be further decreased by at least 20.95% when using the Chen-Guo model coupled with the modified HLS type correlation. Besides, this modified model also shows a better performance in predicting the phase equilibria of C2H6 and CO2 hydrates in the presence of these organic inhibitors than the Chen-Guo model coupled with HLS correlation do.

High-efficiency water vapor absorption by tri-ethylene glycol combined with methyldiethanolamine

• MDEA combined with TEG to improve water vapor absorption. • Effects of gas/liquid flow rates and MDEA concentration were studied. • The effect of MDEA concentration on foaming of solution was investigated. • MDEA had no significant effect on foaming in the experimental condition. • Solution of 10 vol% MDEA and 90 vol% TEG has the highest water vapor absorption. This study investigated methyldiethanolamine (MDEA) effects on gas dehydration using tri-ethylene glycol (TEG) solution in a packed tower. The gas phase has entered the bottom of the contact tower, and it contacted the TEG to separate the moisture after passing through a humidifying tower. The key parameters were the concentration of MDEA in TEG solution, the concentration of water in the solution, and the gas and liquid flow rates. The results revealed that existence of MDEA in the dehydration process did not decrease the absorption efficiency and it even slightly increased the absorption performance of water vapor at some concentrations. The results also showed that increasing the liquid flow rate has a little effect on the absorption efficiency which can be due to the very high solubility of water vapor in TEG. However, the gas flow rate increase reduced the absorption efficiency, which showed that the main mass transfer resistance was in the gas phase. Also, the presence of 5 vol% water in the absorbent solution reduces the water vapor absorption efficiency by approximately 20%. Finally, the effect of MDEA concentration on foaming of solution was investigated, and it was shown that the presence of MDEA had no significant effect on foaming in the experimental condition.

Solvent Regeneration by Thermopervaporation in Subsea Natural Gas Dehydration: An Experimental and Simulation Study

An in-house designed membrane process suitable for subsea natural gas dehydration was studied. The use of a membrane absorber together with a thermopervaporation (TPV) unit for solvent regeneration in a closed loop enables the effective and clean production of high-pressure natural gas close to the wellhead. This process avoids the continuous chemical injection for preventing hydrate formation in natural gas pipelines. The regeneration of the absorbent agent (triethylene glycol (TEG)) by TPV in the closed loop is highly energy-efficient, owing to the unlimited free cooling energy from the cold subsea water. In this work, the performance of membranes in TPV for TEG regeneration was evaluated experimentally for the first time. Morphological and permeation characterizations of an AF2400 thin-film composite membrane were carried out, and high separation factors outperforming the vapor–liquid equilibrium (VLE) were obtained for the solutions containing various water contents at feed temperatures ranging from 30 to 70 °C. The highest values of a separation factor (128,000) and a permeability (2380 (Barrer)) were obtained for the TEG solution containing 30 wt % water at 30 °C, while the highest water flux (468 (g/m2·h)) was reached at 70 °C. Moreover, the concentration polarization phenomenon induced by the temperature gradient was revealed in the membrane’s vicinity of the feed channel. A 3D computational fluid dynamics simulation was performed over the entire module to correct the driving force for a more precise assessment of the membrane permeance. The temperature and concentration profiles in the membrane module domains were explored, and a good agreement with experimental data was obtained.

Air dehumidification using various TEG based nano solvents in hollow fiber membrane contactors

In this study, tri-ethylene glycol (TEG) based nanofluids of carbon nanotubes (CNT), silica (SiO2) and aluminum oxide (Al2O3) in different weight percents of 0.01 and 0.05 wt% were employed to improve the properties of TEG for water vapor absorption in a hollow fiber membrane contactor (HFMC). To do so, the impact of various operational parameters including nanofluid type, nanoparticles (NPs) concentration, liquid and gas flow rate on water vapor separation were elucidated. According to obtained results, CNT nanofluid was more capable on water vapor absorption toward SiO2 and Al2O3, so that the injection of CNT nanofluid led to water vapor absorption enhancement up to 10.8 % as compared to TEG solution alone. The results also indicated that the gas flow rate has an inverse relationship with the amount of water vapor absorption efficiency, whereas increasing the liquid flow rate has no tangible effect on absorption efficiency, which is because of the very high solubility of water vapor in TEG. Ultimately, dynamic light scattering (DLS) analysis was carried out to evaluate the stability of nanofluids and size distribution of nanostructures in the base fluid.

Synthesis of monodisperse SnCo nanoparticles in triethylene glycol and its carbon composites for advanced lithium-ion batteries

The tin-based materials are one kind of the most promising high-capacity anode candidates for advanced Li-ion energy storage systems. However, they still face the problem of large volume expansion during charge–discharge processes, which causes rapid capacity decay and thus largely limit their serving life in practical application. In this work, ultra-fined SnCo alloy particles were successfully synthesized by a facile reduction of metal salts in triethylene glycol (TEG) solution, and then SnCo-anchored carbon composites were obtained through the calcination of SnCo-doped poly-(2-ethyl-2-oxazoline) (PEtOx) clusters. The microstructure, morphology, chemical composition and phase constitution are systematically analyzed. It is found that the as-prepared SnCo alloy particles exhibit a uniformly dispersed spherical morphology with a small average grain size of 20 nm and also a high reversible capacity of 459.1 mAh g[Formula: see text] after 100 cycles. More significantly, the SnCo/C nanocomposites present an excellent capacity retention ratio of 91.1% over 200 cycles at 100 mA g[Formula: see text] as well as good rate capability, suggesting that due to the accelerated electrons and Li[Formula: see text] transportation, the introduction of carbon matrix could significantly improve the stability of the active SnCo nanoparticles and inhibit the occurrence of their volume expansion during cycling.

Density, viscosity, surface tension and intermolecular interaction of triethylene glycol and 1,2-diaminopropane binary solution &amp; its potential downstream usage for bioplastic production

In this work, triethylene glycol (TEG) and 1,2-diaminopropane (DAP) binary mixture was proposed as a novel CO2 capturing solution. In order to understand the binary system better, the key physical and chemical properties of TEG and DAP binary solution including the density, viscosity and surface tension were determined and analyzed. The excess molar volume (VmE), viscosity deviation (Δη) and surface tension deviation (Δγ) of the solution were calculated and fitted by Redlich-Kister (R-K) equation to evaluate the factor and standard deviations between the experimental and calculated quantities. Meanwhile, the as-determined UV–Vis, FTIR, and Fluorescence spectra suggested that intermolecular hydrogen bonds were formed within the binary solution. In term of the excess molar volume, the intermolecular bonds were closely formed when the molar ratio of TEG to DAP was at 1: 1. This system showed strong CO2 capture capability, in which about 0.34 g CO2 was absorbed by per gram of DAP and TEG system. The resulting CO2-Storage Material (CO2SM) was further applied as potential carbon source for Poly-β-hydroxybutyrate (PHB, bioplastic) production by a photoautotrophic-cyanobacterium, and intracellular content of 12.92 wt% was achieved. This work used new biological methods to convert CO2, the fundamental, physical and chemical properties of the alcohol-amine system were studied, further, the basic data as the reference were provided for PHB downstream synthesis optimization.

Analysis of design parameter effects on gas dehumidification in hollow fiber membrane contactor: Theoretical and experimental study

Tri-ethylene glycol (TEG) solution is an appropriate solvent for the effective separation of water vapor from the gas stream. In this study, a comprehensive two-dimensional axisymmetric mathematical modeling has been performed for simulation of water absorption into tri-ethylene glycol solution in a hollow fiber membrane contactor. The obtained governing equations for different sections of membrane contactor (tube side, membrane and shell side) along with the proper boundary conditions have been solved with the aid of COMSOL Multiphysics software. The experiment has been conducted to validate the proposed model and confirm the calculated values by the model. The effects of different parameters such as gas flow rate, desiccant solvent flow rate, TEG concentration, flow direction and wetting on membrane performance have been investigated using the model. The experimental data and predicted values are in excellent agreement with an error of only 2%, indicating the validation of CFD model for process simulation. The results reveal that the resistance in the liquid phase is not the limiting factor for this system. Also, membrane wetting by tri-ethylene glycol could decrease the absorption flux significantly.

Copper selenide crystallites synthesized using the hot-injection process

Nearly dispersed CuSe and Cu2−xSe crystals were successfully prepared using copper and selenium–triethylene glycol (TEG) solution thermal decomposition using triethylenetetramine (TETA) as the reducing agent and polyvinylpyrrolidone (PVP) as the capping agent at 230°C for 1h. The crystalline structure, electronic and copper selenide particles optical characterization were investigated using transmission electron microscopy (TEM), X-ray diffractometer (XRD), UV–visible absorbance spectra. The TETA addition effects on crystal phase development and morphology were investigated. The obtained copper selenides are CuSe and Cu2−xSe single phase for the samples added with TETA of 0.7 and 2.2ml, respectively. The measured energy gaps for CuSe and Cu2−xSe are 2.0eV and 2.17eV, respectively. These synthesized compounds provide promising candidates for solar cell applications.

Carbon dioxide solubility in Triethylene Glycol and aqueous solutions

CO2 transportation has become a hot topic for research due to its implications for Carbon Capture and Storage (CCS) as well as Enhanced Oil Recovery (EOR). Triethylene Glycol (TEG) is one of the most commonly used chemicals in the gas processing industry. It is used in glycol dehydration units as well as occasionally for hydrate inhibition, hence for economic engineering design, it is essential to understand its phase behavior in the presence of CO2 and/or water. The solubility data are essential in adjusting binary interaction parameters used in predicting inhibitor distribution in multi-component systems. A number of measurements were made to determine the solubility of CO2 in TEG and 90, 60 and 40 weight percent (wt %) TEG solutions. These measurements were conducted in the range of 263.15–343.15 K and 0.3–37 MPa. The experimental measurements from this work are compared to open literature data available together with the thermodynamic model calculations. The solubility of CO2 in TEG and aqueous solutions were correlated with CPA-SRK72 model, using a single variable binary interaction parameter. The CPA-SRK72 EoS showed an absolute average deviation of 2.55% for pure TEG.

Solid solution synthesis of (In1−xGax)2Se3 Nanocrystals (0≤x≤1) by a triethylene glycol based solution process

(In1−xGax)2Se3 nanocrystals (0≤x≤1) were synthesized by a facile, air pressure ethylenediamine/N-dodecyl mercaptan co-assisted triethylene glycol solution process using InCl3·4H2O, GaCl3 and Se powder as precursors. The synthesized products were deposited on clean glass substrates by nanocrystals ink dip-coating method, and then were annealed at 500°C for 1h. Morphologies, solid solution stoichiometries, phase compositions, band gap energies and Hall parameters of the synthesized (In1−xGax)2Se3 nanocrystals with solid solution range of 0≤x≤1 were investigated. Results showed that the solid solution stoichiometry could be well tuned by changing precursor atom ratios in the reaction solution. (In1−xGax)2Se3 products showed a phase transformation from wurtzite to zinc-blende in the range from x=0.4–0.5, accompanying change of band gap energies and Hall parameters.

Experimental and theoretical investigation on Nano-fluid surface tension

Effect of γ-Al2O3 and MgO nanoparticle on surface tension of Tri Ethylene Glycol (TEG) was studied for different nanoparticle concentrations. Furthermore, the effect of nanoparticle size on the Nano-fluid surface tension was investigated. Results showed that surface tension increases for some particle concentrations and decreases for some others; in other words, a certain particle concentration could not be determined as the boundary for the increase or decrease of surface tension. Moreover, Sorbitan oleate was added to TEG solution to investigate the changes in surface tension that may occur due to the addition of surfactants. It is shown that by increasing surfactant concentration, Nano-fluid surface tension would decrease. The effect of nanoparticle size on surface tension was analyzed as well. Using experimental data, five empirical and thermodynamic-based models; i.e., Redlich–Kister (RK), Malanovsky-Marsh (MM), Jufu et al. (JBZ), Chunxi et al. (CWZ) and Santos et al. (SFF) were evaluated for surface tension estimation, and it was found that SFF method is the best method to correlate nano fluid surface tension in this study.

Prediction performance of natural gas dehydration units for water removal efficiency using a least-square support vector machine

Natural gas dehydration unit is employed to eliminate water from natural gas liquids and natural gas, and it is needed to avoid condensation of free water and creation of hydrates in transportation and processing facilities, prevent corrosion, and meet a water content condition. In this paper, a least-square support vector machine (LSSVM) coupled with genetic algorithm (GA) was employed to estimate the water dew point of a natural gas stream in equilibrium with a triethylene glycol (TEG) solution at different TEG concentrations and temperatures. Results showed that GA–LSSVM accomplishes more reliable outputs compared with real recorded data in terms of statistical criteria.

Large-scale fabrication and application of magnetite coated Ag NW-core water-dispersible hybrid nanomaterials.

In this work, we report a large scale synthetic procedure that allows attachment of magnetite nanoparticles onto Ag NWs in situ, which was conducted in a triethylene glycol (TREG) solution with iron acetylacetonate and Ag NWs as starting materials. The as-prepared Ag NW/Fe3O4 NP composites are well characterized by SEM, TEM, XRD, XPS, FT-IR, and VSM techniques. It was found that the mass ratio of iron acetylacetonate to Ag NWs plays a crucial role in controlling the amount of magnetite nanoparticles decorated on the Ag NWs. The resulting Ag NW/Fe3O4 NP composites exhibit superparamagnetic properties at room temperature, and can be well dispersed in aqueous and organic solutions, which is greatly beneficial for their application and functionality. Thus, the as-prepared magnetic silver nanowires show good catalytic activity, using the catalytic reduction of methylene blue (MB) as a model reaction. Furthermore, the Ag NW/Fe3O4 NP composites can be functionalized with polydopamine (Pdop), resorcinol-formaldehyde resin (PFR), and SiO2, respectively, in aqueous/ethanol solution. Meanwhile they can also be coated with polyphosphazene (PZS) in organic solution, resulting in a unique nanocable with well-defined core shell structures. Besides, taking Ag NW/Fe3O4@SiO2 as an example, a hollow magnetic silica nanotube can be obtained with the use of Ag NWs as physical templates and a solution of ammonium and H2O2. These can greatly improve the application of the Ag NW/Fe3O4 NP composites. The as-synthesized above nanocomposites have high potential for applications in the fields of polymers, wastewater treatment, sensors, and biomaterials.