Records with Subject: Reaction Engineering
Showing records 1 to 25 of 146. [First] Page: 1 2 3 4 5 Last
Catalytic Aquathermolysis of Boca de Jaruco Heavy Oil with Nickel-Based Oil-Soluble Catalyst
Alexey V. Vakhin, Firdavs A. Aliev, Irek I. Mukhamatdinov, Sergey A. Sitnov, Andrey V. Sharifullin, Sergey I. Kudryashov, Igor S. Afanasiev, Oleg V. Petrashov, Danis K. Nurgaliev
July 2, 2020 (v1)
Keywords: aquathermolysis, catalyst, heavy oil, in situ upgrading, nickel, SARA-analysis
This paper investigates aquathermolysis of heavy oil in carbonate reservoir rocks from Boca de Jaruco, which is developed by the cyclic steam stimulation method. The nickel-based catalyst precursor was introduced in order to intensify the conversion processes of heavy oil components. The active form of such catalysts—nickel sulfides—are achieved after steam treatment of crude oil at reservoir conditions. The experiments were carried out on a rock sample extracted from the depth of 1900 m. Changes in composition and structure of heavy oil after the conversion were identified using SARA-analysis, Gas Chromatography-Mass Spectroscopy of saturated fractions, FTIR spectroscopy of saturated fractions, and MALDI of resins. It is revealed that catalyst particles provide a reduction in the content of resins and asphaltenes due to the destruction of carbon-heteroatom bonds. Moreover, the destruction of C=Carom. bonds and interactions with aromatic rings are heightened. In contrast, the results o... [more]
Catalytic Performance of Metal Oxides Promoted Nickel Catalysts Supported on Mesoporous γ-Alumina in Dry Reforming of Methane
Anis H. Fakeeha, Abdulaziz A. Bagabas, Mahmud S. Lanre, Ahmed I. Osman, Samsudeen O. Kasim, Ahmed A. Ibrahim, Rasheed Arasheed, Abdulmajeed Alkhalifa, Ahmed Y. Elnour, Ahmed E. Abasaeed, Ahmed S. Al-Fatesh
July 2, 2020 (v1)
Keywords: Dry Reforming, Gd-promoted catalyst, mesoporous γ-alumina, metal oxide promoters, methane, Ni-based catalyst, synthesis gas
Dry reforming of CH4 was conducted over promoted Ni catalysts, supported on mesoporous gamma-alumina. The Ni catalysts were promoted by various metal oxides (CuO, ZnO, Ga2O3, or Gd2O3) and were synthesized by the incipient wetness impregnation method. The influence of the promoters on the catalyst stability, coke deposition, and H2/CO mole ratio was investigated. Stability tests were carried out for 460 min. The H2 yield was 87% over 5Ni+1Gd/Al, while the CH4 and CO2 conversions were found to decrease in the following order: 5Ni+1Gd/Al > 5Ni+1Ga/Al > 5Ni+1Zn/Al > 5Ni/Al > 5Ni+1Cu/Al. The high catalytic performance of 5Ni+1Gd/Al, 5Ni+1Ga/Al, and 5Ni+1Zn/Al was found to be closely related to their contents of NiO species, which interacted moderately and strongly with the support, whereas free NiO in 5Ni+1Cu/Al made it catalytically inactive, even than 5Ni/Al. The 5Ni+1Gd/Al catalyst showed the highest CH4 conversion of 83% with H2/CO mole ratio of ~1.0.
Thermal Biomass Conversion: A Review
Witold M. Lewandowski, Michał Ryms, Wojciech Kosakowski
July 2, 2020 (v1)
Keywords: Biomass, gasification, pyrolysis, thermal conversion, torrefaction
In this paper, the most important methods of thermal conversion of biomass, such as: hydrothermal carbonization (180−250 °C), torrefaction (200−300 °C), slow pyrolysis (carbonization) (300−450 °C), fast pyrolysis (500−800 °C), gasification (800−1000 °C), supercritical steam gasification, high temperature steam gasification (>1000 °C) and combustion, were gathered, compared and ranked according to increasing temperature. A comprehensive model of thermal conversion as a function of temperature, pressure and heating rate of biomass has been provided. For the most important, basic process, which is pyrolysis, five mechanisms of thermal decomposition kinetics of its components (lignin, cellulose, hemicellulose) were presented. The most important apparatuses and implementing devices have been provided for all biomass conversion methods excluding combustion. The process of combustion, which is energy recycling, was omitted in this review of biomass thermal conversion methods for two reasons.... [more]
Hydrogen Production by Partial Oxidation Reforming of Methane over Ni Catalysts Supported on High and Low Surface Area Alumina and Zirconia
Anis Fakeeha, Ahmed A. Ibrahim, Hesham Aljuraywi, Yazeed Alqahtani, Ahmad Alkhodair, Suliman Alswaidan, Ahmed E. Abasaeed, Samsudeen O. Kasim, Sofiu Mahmud, Ahmed S. Al-Fatesh
July 2, 2020 (v1)
Keywords: Al2O3, calcination, partial oxidation, reforming of methane, supported nickel, ZrO2
The catalytic activity of the partial oxidation reforming reaction for hydrogen production over 10% Ni supported on high and low surface area alumina and zirconia was investigated. The reforming reactions, under atmospheric pressure, were performed with a feed molar ratio of CH4/O2 = 2.0. The reaction temperature was set to 450−650 °C. The catalytic activity, stability, and carbon formation were determined via TGA, TPO, Raman, and H2 yield. The catalysts were calcined at 600 and 800 °C. The catalysts were prepared via the wet-impregnation method. Various characterizations were conducted using BET, XRD, TPR, TGA, TPD, TPO, and Raman. The highest methane conversion (90%) and hydrogen yield (72%) were obtained at a 650 °C reaction temperature using Ni-Al-H-600, which also showed the highest stability for the ranges of the reaction temperatures investigated. Indeed, the time-on-stream for 7 h of the Ni-Al-H-600 catalyst displayed high activity and a stable profile when the reaction tempera... [more]
Study on the Effect of Iron-Based Deoxidizing Inhibitors for Coal Spontaneous Combustion Prevention
Chaoyu Hao, Yanling Chen, Jiren Wang, Cunbao Deng, Guang Xu, Fengwei Dai, Rui Si, Hongfei Wang, Haoyu Wang
June 23, 2020 (v1)
Keywords: coal spontaneous combustion, comparative experiment, coordination resistance, iron-based deoxidizing inhibitor, oxygen consumption
To improve the prevention of spontaneous coal combustion, reduced iron powder and other ingredients should be added together to form an iron-based deoxidizing inhibitor, with the dual effect of oxygen consumption and inhibition. The oxygen consumption rate of the inhibitor was studied through experiments. According to the theory of coordination resistance, the coordination resistance of Fe3+ was studied via the density functional method. Subsequently, a comparative experiment of the effects on spontaneous coal combustion was conducted. The research shows that several kinds of common resistance agents that are added to the reduced iron powder can consume oxygen. However, the rate of oxygen consumption varies. Fe3+ produced by the reduced iron powder indicates a strong coordination resistance. When compared with traditional inhibitors of Mg2+, Fe3+ has a stronger inhibition effect on the N, P, and S reactive groups in coal. The overall inhibitory effect is better than that of traditional... [more]
Thermal and Torrefaction Characteristics of a Small-Scale Rotating Drum Reactor
Nitipong Soponpongpipat, Suwat Nanetoe, Paisan Comsawang
June 23, 2020 (v1)
Keywords: energy yield, heat loss, heating rate, mass yield, rotating drum reactor, torrefaction
The small-scale rotating drum reactor (SS-RDR) was designed and constructed without using purge gas for the purpose of household application. The thermal and torrefaction characteristics of SS-RDR were studied and compared with other reactor types. It was found that the heat loss at the reactor wall and heat loss from exhaust gas of the SS-RDR were in the range of 6.3−12.4% and 27.9−42.8%, respectively. The increase of flue gas temperature resulted in the decrease of heat loss at the reactor wall and the increase of heat loss from exhaust gas. The heating rate of the SS-RDR was in the range of 7.3−21.4 °C/min. The higher heating value (HHV) ratio, mass yield, and energy yield ofthe SS-RDR were in the range of 1.2−1.6, 35.0−81.0%, and 56.2−96.5%, respectively. A comparison of torrefaction characteristics of various reactor types on HHV ratio-mass yield-iso-energy yield diagram indicated that the torrefaction characteristics of the SS-RDR were better than that of the rotating drum reacto... [more]
Oxidation and Characterization of Low-Concentration Gas in a High-Temperature Reactor
Jinhua Chen, Guangcai Wen, Song Yan, Xiangyun Lan, Lu Xiao
June 23, 2020 (v1)
Keywords: gas, high-temperature oxidation, low-concentration, reactor
To achieve the efficient utilization of low-concentration mine gas, reduce resource waste and alleviate environmental pollution, the high-temperature oxidation of low-concentration gas at a concentration range of 1.00% to 1.50%, which is directly discharged into the atmosphere during coal mine production, was carried out to recover heat for reuse. The gas oxidation equipment was improved for the heating process and the safety of low-concentration gas oxidation under a high-temperature environment was evaluated. The experimental results showed that the reactor could provide a 1000 °C high-temperature oxidation environment for gas oxidation after installing high-temperature resistant ceramics. The pressure variation curves of the reactor with air and different concentrations of gas were similar. Due to the thermal expansion, the air pressure slightly increased and then returned to normal pressure. In contrast, the low-concentration gas exhibited a stable pressure response in the high-tem... [more]
Combustion Kinetics Characteristics of Solid Fuel in the Sintering Process
Jihui Liu, Yaqiang Yuan, Junhong Zhang, Zhijun He, Yaowei Yu
June 23, 2020 (v1)
Keywords: apparent activation energy, coupling effect, monomer blended fuel, quasi-particle fuel, quasi-particle structure
In order to systematically elucidate the combustion performance of fuel during sintering, this paper explores the influence of three factors, namely coal substitution for coke, quasi-particle structure and the coupling effect with reduction and oxidation of iron oxide, on fuel combustion characteristics, and carries out the kinetic calculation of monomer blended fuel (MBF) and quasi-granular fuel (QPF). The results show that replacing coke powder with anthracite can accelerate the whole combustion process. MBF and QPF are more consistent with the combustion law of the double-parallel random pore model. Although the quasi-particle structure increases the apparent activation energy of fuel combustion, it can also produce a heat storage effect on fuel particles, improve their combustion performance, and reduce the adverse effect of diffusion on the reaction process. In the early stage of reaction, the coupling between combustion of volatiles and reduction of iron oxide is obvious. The oxi... [more]
Catalytic Oxidation of Methylene Blue by Use of Natural Zeolite-Based Silver and Magnetite Nanocomposites
Aldiyar Kuntubek, Nurassyl Kinayat, Kulyash Meiramkulova, Stavros G. Poulopoulos, Joseph C. Bear, Vassilis J. Inglezakis
June 23, 2020 (v1)
Keywords: clinoptilolite, magnetite, methylene blue, nanoparticles, oxidation, silver, silver oxide, zeolites
This work reports the synthesis of natural zeolite-based silver and magnetite nanocomposites and their application for the catalytic oxidation of methylene blue in water. The zeolite was impregnated with 5.5 wt.% Fe in the form of magnetite nanoparticles with size of 32 nm, and with 6.4 wt.% Ag in the form of silver oxide and metallic silver nanoparticles with sizes of 42 and 20 nm, respectively. The results showed that physical adsorption contributed to the removal of methylene blue by 25−36% and that Fe3O4@NZU is superior to Ag2O@NZU and Ag0@NZU, leading to 55% removal without oxidant and 97% in the presence of H2O2. However, there is no evidence of significant mineralization of methylene blue. The application of reaction rate models showed that the reaction order changes from zero to first and second order depending on the H2O2 concentration.
Renewable Pulverized Biomass Fuel for Internal Combustion Engines
Ashraf Elfasakhany, Mishal Alsehli, Bahaa Saleh, Ayman A. Aly, Mohamed Bassuoni
June 23, 2020 (v1)
Keywords: biomass powder, combustion engines, gasification/devolatilization, micro-scale size, Modelling, renewable fuel, validation
Biomass is currently one of the world’s major renewable energy sources. Biomass in a powder form has been recently proposed as the most encouraging of biomass contours, especially because it burns like a gas. In the current study, biomass powder was examined, for the first time, as a direct solid fuel in internal combustion engines. The aim of the current study was to investigate modeling tools for simulation of biomass powder in combustion engines (CE). The biomass powder applied was in a micro-scale size with a typical irregular shape; the powder length was in the range of 75−5800 μm, and the diameter was in the range 30−1380 μm. Different mechanisms for biomass powder drying and devolatilization/gasification were proposed, including different schemes’ and mechanisms’ rate constants. A comparison between the proposed models and experiments was carried out and results showed good matching. Nevertheless, it is important that a biomass powder simulation addresses overlapping/complicated... [more]
Experimental Study on Hydrothermal Carbonization of Lignocellulosic Biomass with Magnesium Chloride for Solid Fuel Production
Samuel Carrasco, Javier Silva, Ernesto Pino-Cortés, Jaime Gómez, Fidel Vallejo, Luis Díaz-Robles, Valeria Campos, Francisco Cubillos, Stefan Pelz, Sebastian Paczkowski, Francisco Cereceda-Balic, Albero Vergara-Fernández, Magín Lapuerta, Amparo Pazo, Esperanza Monedero, Kent Hoekman
June 22, 2020 (v1)
Keywords: additives, hydrothermal carbonization, lignocellulosic biomass, magnesium chloride, waste to energy
The effect of magnesium chloride as an additive of hydrothermal carbonization (HTC) of lignocellulosic biomass (Pinus radiata sawdust) was studied. The HTC tests were carried out at fixed conditions of temperature and residence time of 220 °C and 1 h, respectively, and varying the dose of magnesium chloride in the range 0.0−1.0 g MgCl2/g biomass. The carbonized product (hydrochar) was tested in order to determine its calorific value (HHV) while using PARR 6100 calorimeter, mass yield by gravimetry, elemental analysis using a LECO TruSpec elemental analyzer, volatile matter content, and ash content were obtained by standardized procedures using suitable ovens for it. The results show that using a dose of 0.75 g MgCl2/g biomass results in an impact on the mass yield that was almost equal to change operating conditions from 220 to 270 °C and from 0.5 to 1 h, without additive. Likewise, the calorific value increases by 33% for this additive dose, resulting in an energy yield of 68%, thus g... [more]
A Review of Methane Activation Reactions by Halogenation: Catalysis, Mechanism, Kinetics, Modeling, and Reactors
David Bajec, Matic Grom, Damjan Lašič Jurković, Andrii Kostyniuk, Matej Huš, Miha Grilc, Blaž Likozar, Andrej Pohar
June 22, 2020 (v1)
Keywords: Catalysis, density functional theory, halogenation, kinetics, mechanism, methane
Methane is the central component of natural gas, which is globally one of the most abundant feedstocks. Due to its strong C−H bond, methane activation is difficult, and its conversion into value-added chemicals and fuels has therefore been the pot of gold in the industry and academia for many years. Industrially, halogenation of methane is one of the most promising methane conversion routes, which is why this paper presents a comprehensive review of the literature on methane activation by halogenation. Homogeneous gas phase reactions and their pertinent reaction mechanisms and kinetics are presented as well as microkinetic models for methane reaction with chlorine, bromine, and iodine. The catalysts for non-oxidative and oxidative catalytic halogenation were reviewed for their activity and selectivity as well as their catalytic action. The highly reactive products of methane halogenation reactions are often converted to other chemicals in the same process, and these multi-step processe... [more]
Biorefining Oat Husks into High-Quality Lignin and Enzymatically Digestible Cellulose with Acid-Catalyzed Ethanol Organosolv Pretreatment
Rushab Chopda, Jorge A. Ferreira, Mohammad J. Taherzadeh
June 10, 2020 (v1)
Keywords: delignification, digestible glucan, high-quality lignin, oat husks, organosolv pretreatment
Oat husks are low-value lignocellulosic residues of oat processing that carry an environmental impact. Their polymers (cellulose, hemicellulose, and lignin) can be converted into a wide variety of value-added products; however, efficient pretreatment methods are needed that allow their fine separation for further tailored valorization. This study pioneered the use of milling-free and low acid-catalyzed ethanol organosolv for the delignification of oat husks, allowing their conversion into three high-quality streams, namely, glucan-rich, lignin-rich, and hemicellulosic compound-rich streams. Temperature, retention time, and solid-to-liquid ratio were found to impact the delignification of oat husks when using a one-factor-at-a-time strategy. The ideal conditions that were found (210 °C, 90 min, and solid-to-liquid ratio of 1:2) culminated into glucan and lignin fractions containing 74.5% ± 11.4% glucan and 74.9% ± 7.6% lignin, respectively. These high-purity lignin fractions open the po... [more]
Thermal Pyrolysis of Polystyrene Aided by a Nitroxide End-Functionality. Experiments and Modeling
Almendra Ordaz-Quintero, Antonio Monroy-Alonso, Enrique Saldívar-Guerra
June 10, 2020 (v1)
Keywords: mathematical modeling, nitroxide mediated polymerization, polystyrene, thermal pyrolysis
The thermal pyrolysis of polystyrene (PS) is gaining importance as the social pressure for achieving a circular economy is growing; moreover, the recovery of styrene monomer in such a process is especially relevant. In this study, a simple thermal pyrolysis process in the temperature range of 390−450 °C is developed. A working hypothesis is that by using a nitroxide-end functionalized PS (PS-T or dormant polymer), the initiation process for the production of monomer (unzipping) during the PS pyrolysis could be enhanced due to the tendency of the PS-T to activate at the nitroxide end. Two types of PS were used in this work, the first one was synthesized by free-radical polymerization (FRP-dead polymer) and the second by nitroxide-mediated polymerization (NMP) using three levels of nitroxide to initiator ratio: 1.3, 1.1, and 0.9. Analysis of the recovered products of the pyrolysis by gas-mass spectroscopy shows that the yield of styrene increases from ∼33% in the case of dead polymer to... [more]
Understanding the Operating Mode of Fe0/Fe-Sulfide/H2O Systems for Water Treatment
Minhui Xiao, Rui Hu, Xuesong Cui, Willis Gwenzi, Chicgoua Noubactep
June 10, 2020 (v1)
Keywords: contaminant removal, iron corrosion, pyrite oxidation, synergetic effects, zero-valent iron
The general suitability of water treatment systems involving metallic iron (Fe0) is well-established. Various attempts have been made to improve the efficiency of conventional Fe0 systems. One promising approach combines granular Fe0 and an iron sulfide mineral to form Fe0/Fe-sulfide/H2O systems. An improved understanding of the fundamental principles by which such systems operate is still needed. Through a systematic analysis of possible reactions and the probability of their occurrence, this study establishes that sulfide minerals primarily sustain iron corrosion by lowering the pH of the system. Thus, chemical reduction mediated by FeII species (indirect reduction) is a plausible explanation for the documented reductive transformations. Such a mechanism is consistent with the nature and distribution of reported reaction products. While considering the mass balance of iron, it appears that lowering the pH value increases Fe0 dissolution, and thus subsequent precipitation of hydroxide... [more]
Temperature Distribution Estimation in a Dwight−Lloyd Sinter Machine Based on the Combustion Rate of Charcoal Quasi-Particles
Ziming Wang, Ko-ichiro Ohno, Shunsuke Nonaka, Takayuki Maeda, Kazuya Kunitomo
June 10, 2020 (v1)
Keywords: Biomass, charcoal combustion rate, coke combustion rate, iron ore sintering process, quasi-particle, temperature distribution
The coke combustion rate in an iron ore sintering process is one of the most important determining factors of quality and productivity. Biomass carbon material is considered to be a coke substitute with a lower CO2 emission in the sintering process. The purpose of this study was to investigate the combustion rate of a biomass carbon material and to use a sintering simulation model to calculate its temperature profile. The samples were prepared using alumina powder and woody biomass powder. To simplify the experimental conditions, alumina powder, which cannot be reduced, was prepared as a substitute of iron ore. Combustion experiments were carried out in the open at 1073 K~1523 K. The results show that the combustion rates of the biomass carbon material were higher than that of coke. The results were analyzed using an unreacted core model with one reaction interface. The kinetic analysis found that the kc of charcoal was higher than that of coke. It is believed that the larger surface a... [more]
Study on the Formation of Complex Chemical Waveforms by Different Computational Methods
Jiali Ai, Chi Zhai, Wei Sun
June 3, 2020 (v1)
Keywords: Belousov–Zhabotinsky reaction, cellular automata, finite difference, partial differential equations
Chemical wave is a special phenomenon that presents periodic patterns in space-time domain, and the Belousov−Zhabotinsky (B-Z) reaction is the first well-known reaction-diffusion system that exhibits organized patterns out of a homogeneous environment. In this paper, the B-Z reaction kinetics is described by the Oregonator model, and formation and evolution of chemical waves are simulated based on this model. Two different simulation methods, partial differential equations (PDEs) and cellular automata (CA) are implemented to simulate the formation of chemical waveform patterns, i.e., target wave and spiral wave on a two-dimensional plane. For the PDEs method, reaction caused changes of molecules at different location are considered, as well as diffusion driven by local concentration difference. Specifically, a PDE model of the B-Z reaction is first established based on the B-Z reaction kinetics and mass transfer theory, and it is solved by a nine-point finite difference (FD) method to... [more]
Machine Learning-Based Prediction of a BOS Reactor Performance from Operating Parameters
Alireza Rahnama, Zushu Li, Seetharaman Sridhar
May 22, 2020 (v1)
Keywords: Artificial Intelligence, BOS reactor, Machine Learning, neural network, steelmaking
A machine learning-based analysis was applied to process data obtained from a Basic Oxygen Steelmaking (BOS) pilot plant. The first purpose was to identify correlations between operating parameters and reactor performance, defined as rate of decarburization (dc/dt). Correlation analysis showed, as expected a strong positive correlation between the rate of decarburization (dc/dt) and total oxygen flow. On the other hand, the decarburization rate exhibited a negative correlation with lance height. Less obviously, the decarburization rate, also showed a positive correlation with temperature of the waste gas and CO2 content in the waste gas. The second purpose was to train the pilot-plant dataset and develop a neural network based regression to predict the decarburization rate. This was used to predict the decarburization rate in a BOS furnace in an actual manufacturing plant based on lance height and total oxygen flow. The performance was satisfactory with a coefficient of determination o... [more]
Effect of Nitrate and Perchlorate on Selenate Reduction in a Sequencing Batch Reactor
Hyun-Woo Kim, Seong Hwan Hong, Hyeoksun Choi
May 22, 2020 (v1)
Keywords: biological selenate reduction, electron donor competition, nitrate, perchlorate, sequencing batch
Selenate removal from a water body is being vigorously debated owing to severe health impact, but inhibitions of coexisting anions have been reported. To suggest a viable treatment option, this study investigates the effect of nitrate and perchlorate on selenate reduction in a laboratory-scale sequencing batch reactor. The experimental design tests how competing electron acceptors (NO3− and ClO4−) and electron donor (acetate) limitations affect selenate reduction in the reactor. Results show that the reactor achieves almost complete selenate reduction within the initial concentration ranges of 0.1−1 mM by enriching selenate-reducing bacteria with appropriate temperature (30 °C) and acclimation period (50 days). We monitored simultaneous selenate and nitrate reduction in the reactor without specific inhibition due to a difference in microbial growth strategy related to electron donor status. Lack of perchlorate-reducing bacteria makes perchlorate addition (0.2 mM) not to be closely asso... [more]
Ultrasonic-Assisted Extraction (UAE) Process on Thymol Concentration from Plectranthus Amboinicus Leaves: Kinetic Modeling and Optimization
Nur Amirah Asifa Raisha Zahari, Gun Hean Chong, Luqman Chuah Abdullah, Bee Lin Chua
May 22, 2020 (v1)
Keywords: kinetic modeling, mechanism, Optimization, Plectranthus amboinicus, response surface methodology (RSM), Ultrasonic-assisted extraction (UAE)
Thymol shows potential medical values and it can be extracted from plants and herbs. In this study, ultrasonic-assisted extraction (UAE) was used to extract thymol from Plectranthus amboinicus leaves. From the extraction kinetics analysis of UAE on thymol, it was found that the highest concentration was collected at temperature of 25 °C with 5.51% of thymol concentration yield. An equilibrium-dependent solid−liquid extraction (EDSLE) model was found to be the best fitted model for thymol extraction using UAE. The parameters for optimization were the temperature of extraction (40 to 60 °C), extraction time (20 to 40 min), and the solid to solvent ratio (1:30 to 1:40 g/mL). The optimal UAE conditions were found at a temperature of 55 °C, 23 min of extraction, and a solid−solvent ratio of 1:35 g/mL. The changes in the structural surface of P. amboinicus after undergoing the UAE process were investigated using scanning electron microscopy (SEM). The possible mechanism of UAE was explained... [more]
Methodologies for the Design of Solar Receiver/Reactors for Thermochemical Hydrogen Production
M.A. Murmura, M.C. Annesini
May 18, 2020 (v1)
Keywords: design, Modelling, Optimization, solar reactor, solar receiver
Thermochemical hydrogen production is of great interest due to the potential for significantly reducing the dependence on fossil fuels as energy carriers. In a solar plant, the solar receiver is the unit in which solar energy is absorbed by a fluid and/or solid particles and converted into thermal energy. When the solar energy is used to drive a reaction, the receiver is also a reactor. The wide variety of thermochemical processes, and therefore of operating conditions, along with the technical requirements of coupling the receiver with the concentrating system have led to the development of numerous reactor configurations. The scope of this work is to identify general guidelines for the design of solar reactors/receivers. To do so, an overview is initially presented of solar receiver/reactor designs proposed in the literature for different applications. The main challenges of modeling these systems are then outlined. Finally, selected examples are discussed in greater detail to highli... [more]
Hydrothermal Polymerization Catalytic Process Effect of Various Organic Wastes on Reaction Time, Yield, and Temperature
Alexis F. Mackintosh, Taesung Shin, Hyunik Yang, Kangil Choe
May 18, 2020 (v1)
Keywords: biofuel, Biomass, HTP catalytic process, hydrothermal carbonization, organic waste
The purpose of this study is to optimize the processing conditions (temperature, pressure, process time, yield rate) for the conversion of biomass to a high-energy density biofuel. The hydrothermal polymerization (HTP) catalytic process has been developed for production of biofuel via hydrothermal processing using an acid-based catalyst. This study has shown that the HTP catalytic process for a reference feedstock lowered the temperature by 10 to 40 °C, reduced the pressure requirement by 1 to 2 MPa, increased the rate of yield by 22%, and shortened the total processing time by up to 3 h when compared to the conventional hydrothermal carbonization (HTC) process. FTIR spectrum analysis of the HTP catalytic biofuel has shown that lignin in the biomass is preserved, while the pure HTC process destroyed the lignin in the biomass. GC/MS analysis of the process liquid determined the changes of the intermediate soluble components as a function of time. By measuring the 2,5-hydroxymethyl furfu... [more]
Investigation into the Suppression Effects of Inert Powders on the Minimum Ignition Temperature and the Minimum Ignition Energy of Polyethylene Dust
Chendi Lin, Yingquan Qi, Xiangyang Gan, Hao Feng, Yan Wang, Wentao Ji, Xiaoping Wen
May 18, 2020 (v1)
Keywords: dust explosion, inert powder, minimum ignition energy, minimum ignition temperature, suppression effect
The risks associated with dust explosions still exist in industries that either process or handle combustible dust. This explosion risk could be prevented or mitigated by applying the principle of inherent safety. One effective principle is to add an inert material to a highly combustible material in order to decrease its ignition sensitivity. This paper deals with an experimental investigation of the influence of inert dust on the minimum ignition temperature and the minimum explosion energy of combustible dust. The experiments detailed here were performed in a Godbert−Greenwald (GG) furnace and a 1.2 L Hartmann tube. The combustible dust (polyethylene—PE; 800 mesh) and four inert powders (NaHCO3, Na2C2O4, KHCO3, and K2C2O4) were used. The suppression effects of the four inert powders on the minimum ignition temperature and the minimum explosion energy of the PE dust have been evaluated and compared with each other. The results show that all of the four different inert dusts have an e... [more]
RF-ICP Thermal Plasma for Thermoplastic Waste Pyrolysis Process with High Conversion Yield and Tar Elimination
Mohamed Aboughaly, Hossam A. Gabbar, Vahid Damideh, Isaac Hassen
May 8, 2020 (v1)
Keywords: gasoline and diesel production, intelligent feedback control system, process control algorithms, radio frequency thermal plasma, Renewable and Sustainable Energy, thermochemical processes, time-dependent 3D comsol simulation, waste-to-energy
This paper demonstrates an RF thermal plasma pyrolysis reaction apparatus that achieves 89 wt.% reaction conversion yield with no tar content. The demonstrated experimental apparatus consists of a 1100 W RFVII Inc. (104 Church St, Newfield, NJ 08344, United States) @ 13.56 MHz RF thermal plasma generator, a Navio matching network, intelligent feedback controller, and an 8-turn copper RF-ICP torch embedded in a 12 L thermochemical reactor. The intelligent feedback controller optimizes the thermal performance based on feedback signals from three online gas analyzers: CO, CO2 and NOx. The feedback controller output signal controls the RF thermal plasma torch current that provides real-time temperature control. The proposed reaction system achieves precise temperature profiles for both pyrolysis and gasification as well as increases end-product yield and eliminates undesired products such as tar and char. The identified hydrocarbon liquid mixture is 90 wt.% gasoline and 10 wt.%. diesel. Th... [more]
Laser-Induced Ignition and Combustion of Individual Aluminum Particles Below 10 μm by Microscopic High-Speed Cinematography
Fengting Hou, Shengji Li, Yue Wang, Xuefeng Huang
May 8, 2020 (v1)
Keywords: combustion mechanism, individual aluminum, laser ignition, microscopic high-speed cinematography, submicron particle
Metal aluminum has been widely used as an ingredient in propellant, gunpowder and thermite, but there is less understanding of the combustion mechanism of aluminum particles from submicron to several microns in diameter. This paper proposes to experimentally investigate the ignition and combustion characteristics of individual aluminum particles below 10 μm. A specific in situ diagnostic experimental apparatus was first designed for directly observing the ignition and combustion behaviors of individual aluminum particles, with a submicrometer spatial resolution and a temporal resolution of tens of microseconds. Direct observation through microscopic high-speed cinematography demonstrated that, when heated by a continuous laser, individual aluminum particles thermally expanded, followed by shell rupture; the molten aluminum core overflowed and evaporated, leading to ignition and combustion. Further results showed that, when the laser power densities were gradually increased (5.88, 7.56... [more]
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