Hungarian Materials and Chemical Sciences and Engineering

Coal Char Steam Gasification of Three Different Hungarian Coal Types

2023-11-03T19:41:42+01:00

In this study, there were two brown coal sample and a black coal sample gasified in a down draft fixed bed reactor at 800 and 900 °C, within 10 g/min of steam flow rate in all experiments. The aim of this research is the investigation of gasification process using Hungarian brown coal char and back coal char samples from pyrolysis process in the distribution of dry gas yields, as well as the synthesis gas composition. Based on the gasification experiments, the brown coal samples showed a potential utilisation for the gasification process. In the case of brown coal samples, the gasification time was shorter at the higher gasification temperature. Using steam as reactant in the gasification process generated a significant quantity of gas with a high hydrogen concentration, which may be suitable to produce secondary raw materials, as methanol.

Hungarian Low Rank Coal Gasification and Single Line Multi-Stage Gasification: Short Review

2023-11-03T20:37:35+01:00

Presently, the thermochemical process is widely used in the utilisation of fossil fuels. In which, gasification processes are the most attractive solutions for the cleaner utilisation of coal. One of the main challenges is the development of the reactor considering a better conversion efficiency. In this paper, the background research shows that there is a field of research with a gap within the gasification of low rank coals, especially regarding the fine-tuning of the synthesis gas composition within the process. There are several research focusing on multistage gasifiers, however, these approaches mainly focused on the multi-stage gasification of biomass fuel to enhance the quality of synthesis gas, especially in the reduction of tar content to use in combustion process as internal combustion engine or combined heat and power plant. In addition, using air as reactant showed the poor result in the ratio of H₂/CO for further direct application in the chemical process.

Developement of Application Tailored Low-Cost Steam Generator for Gasification Process

2023-11-03T21:58:54+01:00

The gasification process is considered as the centre of clean coal technology. Several types of gasifying reactants can be used in the gasification process. Amongst them, using steam is recommended for the high concentration of hydrogen in the synthesis gas. Commercially available steam generators are readily available to purchase in the market. However, their cost and accessibility are the main disadvantages for use in tailored research applications as laboratory scale gasification. In this paper, the development and setting up of a steam generator will be presented, with the mass flow ratecontrolled by a microcontroller. The total power of the steam generator is 1800 W, and the mass flow rate is adjustable between 1 and 20 g/min. The produced steam can be supplied by the steam generator at a high temperature of 300 °C continuosly during the experiment. The main advantage of this steam generator is the cost/value of the tailored setup that could also be easily connected to the main PLC controller of the gasifier.

Pyrolysis of the 3D printing plastic waste

2023-11-03T22:07:13+01:00

The amount of plastic waste generated by 3D printing is growing dramatically; thus, recycling is becoming increasingly vital. This research aims to investigate the potential of pyrolysis technology for the recycling of 3D printing plastic waste by employing thermogravimetric analysis. The pyrolysis of Polyethylene Terephthalate Glycol (PETG), Polylactic Acid (PLA), and Acrylonitrile Butadiene Styrene (ABS) was studied using three different heating rates of 5, 10, and 20 °C/min. As a result, all three materials showed one step of degradation based on thermogravimetric analyses. In addition, different mixtures were also investigated to see the influence of polymer combinations. The thermogravimetric analysis of the three heating rates described above demonstrated two stages of mixture decomposition in the presence of PLA. The findings suggest that the thermal behavior of a mixture, including mass loss and solid residue, can be estimated by calculating a weighted average of the solid residues of individual plastic waste components. This method provides a useful tool for predicting the thermal behavior of mixtures and can aid in the development of more efficient waste management strategies.

Elasticity and Heat Resistivity of Heat-Treated High Voltage Conductors

2023-11-03T22:31:32+01:00

The increase in electricity demand puts a large load on electricity transmission and distribution networks. A quick solution for a given section is to replace the conductor with hightemperature low sag conductors. A continuous operating temperature of 150–200 °C instead of 80 °C means a higher current carrying capacity. However, an important issue is the size of the clearance, that is, the sag of the conductor. It is necessary to consider the change in the sag not only at the operating temperature but also in case of possible overloading. The value of the sag may be different from one span length to another, so it is worth examining the elastic behavior of the conductors in a general study. The article presents the results of this study for three conductors constructed from different aluminum alloys and steel grades. Standard ACSR conductor tested which contain hard drawn, unalloyed aluminum wires and galvanized steel wires. An AACSR conductor is produced with the same construction as ACSR one from alloyed aluminum wires and galvanized high strength steel wire which was also tested. The results compared to the measured values of a high-temperature low sag conductor consisting of heat-resistant aluminum wires and aluminum cladded steel wires.

The Effect of Surface Treatment on the Audible Noise of a High Voltage Conductor

2023-11-03T22:52:34+01:00

The conductors of high-voltage electrical transmission networks emit strong noise in wet weather. It is caused by the formation of corona radiation on their surface. The high electrical field gradient at the surface deforms the water droplets formed on the conductors’ and the droplets amplify the corona radiation. The corona radiation not only indicates noise, but it is a loss too. The reduction of the corona radiation also reduces the loss of the transmission. Reducing the intensity of corona radiation can be achieved by improving the wettability of the surface to hinder the formation of large droplets. One way to do this is to blast the surface. However, in addition to the study of wettability, an important question is how the conductor behaves during operation. It is possible to examine in laboratory conditions with the application of high voltage and artificial rainfall. The experience gained from this type of experiment is presented in the article.

Enhancing the Metal Yield of the Rotary Converter Melting of Aluminium Drosses with Simple Sodium-Chloride: Thermodynamic and Kinetic Consideration

2023-11-04T10:53:29+01:00

The rotary converter melting of Al-containing drosses with and without NaCl addition was examined. It was found that simple NaCl can enhance the recovery by 9% while decreasing the mass of the secondary dross. It implied a significant decrease in the metallic Al concentration, which indicates a superior coalescence of the molten metal drops when NaCl is present. However, the thermodynamic analysis showed that it might also imply the possibility of a certain degree of aluminothermic and magnesiothermic reduction of NaCl. On the other hand, neither the analysis of the flue dust nor that of the tapped metal showed the presence of the reaction products; thus, no melt contamination occurred.

The Fundamental Aspects of Ferro-Alloy Production from Spent Lithium-Ion Batteries by Reduction Using Calcium-Aluminate Slags

2023-11-04T11:30:30+01:00

The production of ferro-alloys from waste Li-ion batteries has been examined thermosdynamically and experimentally. It was found that Co and Ni can be reduced even with relatively low pCO/pCO₂ratios in the gas phase, while the reduction of Mn or Fe requires strongly reducing conditions and higher temperatures. Even the reduction and selective recovery of Li are thermodynamically possible due to the possible evaporation. The optimum slag compositions were evaluated theoretically, followed by an experimental investigation. Ferrocobalt, ferrocobalt-nickel and ferrocobalt-nickelmanganese were produced using calcium-magnesium-ferrite type slags. Furthermore, secondary Al dross – containing Al – was also tested both as a reducing and a slag-forming agent for the production of ferrocobalt and ferromanganese affiné.

The Recovery of Pure Zinc from Spent Pickling Liquor by Combining Anion Exchange and Electrodeposition

2023-11-04T16:52:38+01:00

Zn recovery from spent pickling liquors (SPL) from hot dip galvanization was examined with modelled solutions by combining anion exchange separation and electrodeposition processes. The solution was purified to be suitable for the electrodeposition of Zn with the main goal of eliminating the iron content. The anion-exchange resin bed in a chromatographic column primarily retained Zn, while divalent Fe was removed in the loading and rinsing steps. At the end of the process, the elution of Zn was carried out by a significantly reduced Cl– ion background. In parallel with the purification process, the potentiodynamic study (1 min runs at 40 mV/s polarization speed) of Zn electrodeposition in the series of Fe concentrations was examined. During the separation process, the preliminary reduction of the iron to its divalent state was found to be of utmost importance. The separation of iron could be improved by controlling the preliminary reduction. It was found that the effect of iron concentration on the polarization curves is complex. Initially, hydrogen bubble formation causes inhibition, but at higher iron concentrations a Zn-Fe deposit is soon formed, promoting hydrogen evolution, thereby depressing polarization but also the current efficiency. The loss of the dendritic structure obtained from pure zinc solutions also characterizes the effect of mixed Fe-Zn deposition. In order to recover pure zinc at the cathode, the pre-purification of the Zn electrolyte is essential.

Bond Dissociation Enthalpy as a Tool to Study Urethane Degradation

2023-11-04T17:19:13+01:00

Polyurethane is the most important class of polymers. It contains several urethane bonds, which connect the building blocks of the polymer. Thus, the chemical recycling and the degradation of the polymer depend on the strength of the urethane bond. To better understand polyurethane degradation at the molecular level, three model systems were created, carbamic acid, methyl N-methylcarbamate, and phenyl N-phenyl carbamate, and studied by using computational chemical tools. Each of the model compounds contained one urethane bond. Thus, the effect of various functional groups around this motif can be studied by comparing the corresponding bond dissociation enthalpies (BDEs) within these compounds. The BDEs were computed by using the B3LYP density functional theory (DFT) method in combination with the 6-31G(d) basis set in the gas phase. It was found that in the case of phenyl Nphenyl carbamate, the degradation is more probable because the corresponding BDEs are lower than in the other two compounds.

Analysis of Molecular Dynamics Simulation of Carbonic Anhydrase

2023-11-04T18:06:51+01:00

Molecular Dynamics (MD) simulation is a computational method for analyzing the physical movements of atoms and molecules allowed to interact for a fixed duration of time. In this study, the thermal stability of carbonic anhydrase, which catalyzes the reaction of water and carbon dioxide, was investigated. Our simulations were performed in a box of water at four different temperatures, 300 K, 310 K, 320 K, and 330 K. The duration of each simulation was 100 ns, and thereafter the hydrogen bonds, Solvent Accessible Surface Area (SASA), as well as Root Mean Square Deviation (RMSD) were analyzed. Moreover, cluster analysis was done to identify representative structures at each temperature. The results showed that changing the temperature did not significantly impact the number of hydrogen bonds. The SASA had more fluctuation when the temperature increased. Moreover, the higher the temperature of the simulation was, the more clusters were obtained. The higher number of clusters indicates higher conformational flexibility and less-stable conformers forming during the simulation.

Investigating Collagen as a Bio-Material by Molecular Dynamics Simulations

2023-11-04T20:56:28+01:00

In this work, molecular dynamics simulation is used to describe and analyze the behavior of model collagen polymer (Pro-Pro-Gly)9. This project aims to highlight the important role of molecular dynamic simulation in determining the structural stability of collagen, and establishing collagen as a hydrophobic or hydrophilic protein under different temperatures. The system was simulated at four different temperatures (300, 310, 320, and 330 K). The results indicate that the average number of hydrogen bonds within the protein and the protein backbone was similar at each temperature. The solvent-accessible surface area of hydrophobic and hydrophilic atoms for the four temperatures indicates that the collagen model peptide is mostly hydrophobic. All the results show that the structure of the studied polymer was the least stable at 320 K and the most stable at lower temperatures (300 K). The average effect across the first 100 ns was investigated. The dominant states obtained within this time interval will be explored in following studies. Researchers can use the results of this work to develop collagen with the appropriate thermal stability for biological applications.

Salt Recovery from the Hot Treated Aluminium Melting Dross Residue

2023-11-04T21:26:58+01:00

In the aluminium industry, the large amount of dross – a by-product of scrap melting – is usually further processed at high temperature re-melting to reclaim the high metallic content entrapped in material. The residue of the hot dross treatment is mainly composed of oxides, and chloride salts from the flux added during the thermo-mechanical process. The major NaCl and KCl components of the added salt are removed by a technically simple leaching process, however, the brine must be treated to remove the dissolved chlorides. We have investigated the energy requirement and efficiency of the evaporation procedure with a simple vessel of insulated walls and submerged heater. The specific heat capacity of the examined NaCl/KCl saturated solution of 2 : 1 mass ratio was determined as ~3155 J/kgK and the latent heat as 1538 J/kgK. The heat efficiency obtained with the system at room temperature initially was found to approach a 97% level as stable conditions were reached. The crystallized NaCl/KCl salt mixture – with possible modifications of it composition – can be recycled to the furnace.