Using Physical Modeling to Optimize the Aluminium Refining Process

This research investigates bio-oil production from soursop seed through pyrolysis, with process modelling and optimization conducted using RSM via Box-Benkhen design. Soursop seeds were oven-dried, ground, and sieved into various particle sizes within 1.0 to 6 mm range before undergoing pyrolysis at temperatures between 400 to 600 °C under inert nitrogen gas flow rates between 1.0 to 1.5 L/min. A Box-Behnken design under Response Surface Methodology (RSM) was used to model and optimize the effects of temperature, particle size, and inert gas flow on bio-oil yield. Proximate and ultimate analyses characterized the feedstock, while SEM revealed a porous structure favorable for pyrolysis. Bio-oil was characterized using FTIR and GC-MS to identify key functional groups and fatty acid composition. Proximate analysis showed the seeds had high volatile matter and fixed carbon, indicating good potential for pyrolysis. Ultimate analysis revealed carbon, hydrogen, nitrogen, oxygen, and sulphur contents of 51.29%, 5.90%, 0.50%, 42.30%, and 0.01%, respectively. Scanning Electron Microscopy (SEM) showed a rough, porous structure with oil-like droplets on the surface, which enhanced pyrolysis efficiency by providing a larger reactive surface area and improving devolatilization rates. The experimental design considered temperature, particle size, and gas flow rate combinations, with the bio-oil yield as the response. Results showed that increases in these parameters significantly affected bio-oil production. The maximum observed yield of 33.1% was achieved at 500°C, 6 mm particle size, and 1.0 L/min gas flow. The RSM model showed a high degree of fit with an R² value of 0.9875, adjusted R² of 0.9715, and predicted R² of 0.8007. Optimization predicted a maximum yield of 31.43% under conditions of 461.84°C, 3.84 mm particle size, and 1.02 L/min flow rate, with a desirability of 1.0. Experimental results closely matched these predictions, validating the model. Similarly, FTIR analysis indicates that the predominant monounsaturated fatty acid made up 45.55% of the total fatty acid content, which depicts that the oil belongs to the linoleic acid group. Furthermore, the FTIR analysis reveals that the alkene group contributes to increased reactivity and combustion efficiency, boosts the octane number of the bio-oil, and decreases the boiling point of the oil. Therefore, the FTIR and GC-MS analysis findings confirm that the bio-oil was within ASTM specifications.

Membrane evaporation of amine solution for energy saving in post-combustion carbon capture: Performance evaluation

In 2021, estimation shows that the worldwide annual hydrogen production is around 94 Mt. Exploitation of native hydrogen being not mature, it is obtained by its separation from other elements by different methods such as steam methane reforming, and electrolysis of water. The latter supplied by a renewable power source will take part in the development of a green hydrogen economy [1]. In this context, Proton Exchange Membrane (PEM) Electrolyzer is a promising technology due to its flexibility and very quick adaptation to load variations. However, its current development still confronts some limitations at a large industrial scale. For instance, efficiency and durability are directly impacted by the mass transport and electrical transfer within the porous materials at the anode side. Limitation of the water supply to the catalyst layer happens once there is a poor oxygen evacuation which decreases the performance of the device by inducing high overpotential. Furthermore, the PTL has an important role as an electrical conductor for charge transfer from the catalyst layer [1]. The efficiency of all the transport phenomena through the PTL and porous electrode assembly depends on their transport properties which are related to their microstructure and operating conditions. For instance, PTL with a large pore size allows good water and gas transport, while produced electrons choose a long-distance path generating an electrical resistance higher than that in the case of PTL with a small pore size [1]. So, controlled and optimum porosity and pore size could contribute to efficient water, gas, and electron transport. To define the best porous layers morphologies, a deep and accurate understanding of the phenomena is developed in this work by combining modeling and experiments.The magnetic resonance imaging (MRI) technique was used to quantify the water content within the porous layer during the two-phase flow. Instead of the real PTL made of titanium which is paramagnetic and cannot be used in the MRI, borosilicate filters with thickness, porosity, and pore size similar to the PTL were used. After positioning the sample in the 600 MHz vertical imager (Figure 1-A), a constant water flow rate is introduced while the gas flow rate is varied. The saturation profiles measured through the porous material depend on the gas flow rate and a semi-dryness of the sample occurs (Figure 1-B) with a residual quantity trapped between pores (minimum stable water content). The water flow rate variation in the channel does not affect saturation, but a higher gas flow rate is needed to reach a minimum stable water content for higher water flow rate.The gas pressure drop through the porous medium was measured and bubble formation in the channel was also analyzed. The results show that the pressure drops and types of flow (slug, annular, and bubble flow) depend on orientation of the water channel (horizontally and vertically) and flow direction (up or downward), and on the water and gas flow rates.To reach a better understanding of the dynamic characteristics of water and oxygen transport over the PTL, the phase-field model based on the Cahn-Hilliard theory was used to simulate the two-phase flow through a porous medium [2]. In this model, the modified Navier-Stokes equations for two phases are coupled with a phase-field equation for describing the diffuse interface. Numerical simulations performed in the COMSOL® multiphysics software were carried on 2D geometries composed of spherical solid grains of different sizes, having properties similar to the PTL used in the MRI experiments. Gas is injected on one side of the sample and flows through the porous medium initially saturated and evacuated on another side in contact with the water channel (Figure 1-C). Gas flow in the porous medium and bubble formation in the water channel are studied while varying the gas and water flow rates. The simulation results give information about the gas pathways within the porous medium and the saturation profiles over time, depending on the gas/water flow rates, which will be compared with experimental results.[1] J. Parra-Restrepo, “Caractérisation des hétérogénéités de fonctionnement et de dégradation au sein d’un électrolyseur à membrane échangeuse de protons (PEM),” Université de Lorraine, 2020.[2] J. W. Cahn and J. E. Hilliard, “Free Energy of a Nonuniform System. I. Interfacial Free Energy,” The Journal of Chemical Physics, vol. 28, no. 2, pp. 258–267, Feb. 1958. Figure 1

Thermocells represent a promising way to utilize heat as a power source. The aim of this work is to develop a thermocell with identical gas electrodes using molten carbonate-based electrolytes. The cell can generate power from waste heat, and can also utilize the CO2 rich off-gas available in metal producing industries. The flow rate of the gas supply to the electrodes needs to be optimized. Its effect on the Seebeck coefficient was not studied systematically before. The addition of solid oxide to the molten carbonate melt alters also the system's Seebeck coefficient. We report measurements where we vary the content of solid oxide in the liquid eutectic electrolyte mixture as well as the electrode gas flow rate. The Seebeck coefficient is reported for various ratios of eutectic (Li,Na)2CO3 molten carbonate and dispersed solid oxide MgO, and for varying gas (CO2|O2) flow rates to the electrode interfaces.

Analytical aspects of different adjustment of parameters of an inductively coupled plasma atomic emission spectrometer (ICP‐AES) were investigated. The ICP‐AES was a LABTAM 8440M (now called GBC) spectrometer. Since at many times, the elemental concentration of the analyte is near to the detection limit, the lowest possible detection limit has to be reached. When the signal‐to‐background ratio (SBR) is maximized, the detection limit is the smallest. This is the reason why the effects of each adjustable parameters on the signal‐to‐background ratios were investigated. Seven adjustable parameters can be analyzed in this equipment: (i) viewing height, (ii) forward power, (iii) sample gas, (iv) coolant gas, (v) auxiliary gas, (vi) flushing gas, and (vii) sample uptake flow rates. Furthermore aerosol distribution by droplet size and nebulization efficiency were also examined applying three different sample gas flow rates and four elements [iron (Fe), magnesium (Mg), manganese (Mn), and nickel (Ni)]. The alkali metals with low excitation energy [potassium (K), lithium (Li), and sodium (Na)] were detectable in higher regions of the plasma, some alkali‐earth and transition metals with medium excitation energy [calcium (Ca), srontium (Sr), and copper (Cu)] were well detectable in medium height, whereas the maximum signal‐to‐background ratios of the other elements with relatively high excitation energy [e.g. cadmium (Cd), Ni, and phosphorus (P)] reached in lower regions of the plasma. On the basis of results the compromised viewing height for all the elements is found 5 mm, the optimum sample gas flow rate 1.14 dm3 min‐1 and the forward power 1200 W. Change of coolant and auxiliary gas flow rates has not changed the signal‐to‐background ratios significantly. Consequently the optimum argon flow rates in aspect of consumption of argon are the possible lowest flow rates, where plasma remains stable. For coolant and auxiliary gas flow rates these values are 10 dm3 min‐1 and 0.1 dm3 min‐1, respectively. Changing the rate of peristaltic pump (i.e. sample uptake rate) the signal‐to‐background ratios increase to 4‐ or 5‐fold of the original values, therefore the optimum sample uptake rate is considered 4 cm3min‐1. Increase of flushing gas flow rate has not changed the signal‐to‐background ratios significantly, except in case of sulfur (S) and P, because of oxygen (O2) absorption from the air. When analysis of S and P content is necessary, 0.13 dm3min‐1 and 0.2 dm3 min‐1, respectively, of flushing gas flow rate is recommended to use.

Factorial design application to evaluate thermochemical conversion of shredder residues

It is really hard to determine the phenomena occurring during aluminum refining process using argon blowing through the liquid metal in industrial conditions. The solution of such problem is physical modelling. This kind of modelling gives possibility to determine the level of dispersion of the refining gas in liquid metal. Especially in steel metallurgy RTD (Residence Time Distribution) analysis and visualization process with some colour tracer, which can give extra information about time of mixing are very popularly used. Because the modelling research (especially visualization) is pictorial, the research was conducted to check if it is possible to estimate quantitatively impeller working effectiveness basing on determination of the RTD curves. The examined object was model of URO-200 batch refining reactor. The RTD curves was registered and discussed for three different impellers and four different variants of processing parameters (rotary impeller speed: 300-500 rpm, and gas flow rate: 15-20 l·min–1). Additionally, the process of mixing of the inert gas with water as a modelling agent was enabled to be observed due to introduction of colour tracer (KMnO4). Results obtained from both measuring methods were graphically presented, compared and shortly discussed.

Coriolis devices are continuously evolving to meet the demands of different conditions, such as wet gas flow. However, their application in wet gas flow has not yet been thoroughly explored. The impact of steady flow disturbances on Coriolis flow meters is well-documented, and empirical compensation or correction methods can be implemented accordingly. However, there has been inadequate investigation into the response of Coriolis meters under transient flow conditions and their comparison with steady flow in a wet gas. In this study, a Coriolis device was horizontally installed in a 50 mm pipe diameter. The experimental fluids consisted of air and water, with Lockhart-Martinelli (XLM) values ranging from 0.02 to 0.40. Steady and transient flow conditions at different gas and liquid flow rates were studied. The findings demonstrate the capability of standard deviation (STD) in distinguishing transient flow from steady one. Additionally, a strong correlation was observed between XLM and gas Over-Reading (OR) across various gas flow rates and XLM values. This correlation is particularly evident for XLM < 0.1. At extremely low liquid loading (XLM < 0.05), the average percentage error remains below 7 % even without the utilization of any correction models. Furthermore, the impact of different sensor installations, which had been largely overlooked in previous studies, was investigated.

The present paper describes a comparison of the efficiency of different types of rotors used in the refining of aluminium melt at a foundry degassing unit (FDU). Physical modelling was used to obtain data for six different rotor types under defined experimental conditions. In order to evaluate the data from the physical model, an evaluation method based on the interpolation of degassing curves was developed in such a way that the resulting characteristic can be expressed by a single parameter. Using the new methodology, the datasets were replaced by a single dimensionless parameter, a, which characterizes the rotor performance at a given gas flow rate. Based on the comparison of these performance parameters, it was possible to mutually compare the rotor efficiency depending on the selected conditions. The comparison is also demonstrated on the expected degassing time to a certain required concentration. Based on the physical model results, the study found that rotor D had the highest degassing efficiency, followed by rotors F and A. Rotors B and E had similar efficiency at a flow rate of 17 Nl·min−1. However, rotor B showed better efficiency at higher inert gas flow rates (19 and 21 Nl·min−1), while rotor E showed better efficiency at lower flow rates (13 and 15 Nl·min−1).

Physical scale modeling (PSM) is an experimental technology that has been used to evaluate and design shipboard impressed current cathodic protection (ICCP) systems by various researchers and designers. PSM is also a preferred tool for validating ICCP numerical modeling results, owing to the well-controlled conditions in PSM experiments. However, one issue in using PSM for the validation of numerical modeling results is the lack of information on the actual polarization behavior of the cathodes on a model hull during PSM experiments. Consequently, the polarization curve data used as boundary conditions in numerical modeling trials is usually different from the polarization behavior of the cathodes in PSM experiments. This difference can result in a discrepancy between the numerical modeling and the PSM results, which is difficult to separate from other numerical errors. A discrete area current control (DACC) technique was developed in a previous ICCP PSM study to simulate the polarization behavior of a propeller material under various conditions. The present study extended the DACC technique to simulate the polarization curve behavior of four discrete cathodes representing one nickel aluminum bronze (NAB) propeller and three discrete steel patches. This study also demonstrated that use of the DACC technique can ensure that both PSM and numerical modeling studies use identical polarization curve relationships as boundary conditions. The technique facilitates the use of the PSM results for comparison with numerical modeling results. The comparison study showed good agreement between the PSM results and numerical modeling results, in both simulated static and dynamic flow conditions.

The EFSA Panel on Food Contact Materials, Enzymes and Processing Aids (CEP) assessed the safety of the recycling process Ester Industries (EU register number RECYC261) using the recoSTAR PET FG technology. The input is hot washed and dried poly(ethylene terephthalate) (PET) flakes originating from collected post‐consumer PET containers, mainly bottles, with no more than 5% PET from non‐food consumer applications. The flakes are processed continuously under an inert gas flow. They are dried and crystallised in a first reactor and then further heated in a second reactor before being extruded into pellets. Having examined the challenge test provided, the Panel concluded that the drying and crystallisation (step 2), and the heating of the crystallised flakes (step 3) are the critical steps that determine the decontamination efficiency of the process. The operating parameters to control the performance of these critical steps are temperature, residence time and gas flow rate. It was demonstrated that this recycling process is able to ensure that the level of migration of potential unknown contaminants into food is below the conservatively modelled migration of 0.1 μg/kg food. Therefore, the Panel concluded that the recycled PET obtained from this process is not of safety concern, when used at up to 100% for the manufacture of materials and articles for contact with all types of foodstuffs for long‐term storage at room temperature, with or without hotfill. Trays made of this recycled PET are not intended to be used in microwave and conventional ovens and such use is not covered by this evaluation.

Hydrodynamics characteristics of HDS trickle bed test reactor

The effects of ratio of draft tube to reactor diameter (Dd/D), liquid nozzle diameter (dN), aeration tube diameter (dG) and immersion height of the two‐fluid nozzle into the draft tube (HN) on overall and annulus gas holdups for the air‐water system were evaluated experimentally in a reversed flow jet loop reactor over wide ranges of gas and liquid flow rates. Both the gas holdups increased with increasing gas and liquid flow rates and with decreasing dN and HN. The influence of dG on gas holdups is found to vary with gas flow rates. Correlations are proposed to predict gas holdups.

The most of past studies in foaming trickle bed reactors aimed at the improvement of efficiency and operational parameters leads to high economic advantages. Conventionally most of the industries rely on frequently used gas continuous flow (GCF) where operational output is satisfactory but not yields efficiently as in pulsing flow (PF) and foaming pulsing flow (FPF). Hydrodynamic characteristics like regime transitions are significantly influenced by foaming nature of liquid as well as gas and liquid flow rates. This study?s aim was to demonstrate experimentally the effects of liquid flow rate, gas flow rates and liquid surface tension on regime transition. These parameters were analyzed for the air-aqueous Sodium Lauryl Sulphate and air-water systems. More than 240 experiments were done to obtain the transition boundary for trickle flow (GCF) to foaming pulsing flow (PF/FPF) by use excessive foaming 15-60 ppm surfactant compositions. The trickle to pulse flow transition appeared at lower gas and liquid flow rates with decrease in liquid surface tension. All experimental data had been collected and drawn in the form of four different transitional plots which are compared and drawn by using flow coordinates proposed by different researchers. A prominent decrease in dynamic liquid saturation was observed especially during regime transitional change. The reactor two phase pressure evident a sharp rise to verify the regime transition shift from GCF to PF/FPF. Present study reveals, the regime transition boundary significantly influenced by any change in hydrodynamic as well as physiochemical properties including surface tension.

Effects of water-gas two-phase flow on methane hydrate dissociation in porous media