This document discusses a study of the kinetics of self-reducing mixtures composed of iron ore, steel mill waste (BOF dust), and biomass from elephant grass. Kinetic runs were performed using thermogravimetric analysis at temperatures from 900-1100°C and carbon contents of 15-30%. The reaction fractions over time showed good agreement with first-order kinetics. Activation energies were estimated, with the highest kinetic constants occurring at 1100°C with 30% carbon: 0.0037 s-1 for the Fe3O4→FeO reaction and 0.0258 s-1 for FeO→Fe. The kinetic behavior supported chemical reaction control over diffusion control for self-reducing pellet reactions.
The Addition of Aluminum Nanoparticles to Polypropylene Increases Its Thermal...IJERA Editor
This work reports the thermal degradation kinetics of isotactic polypropylene (iPP) and iPP with incorporated Al nanoparticles. The Friedman, Flynn-Wall–Ozawa (FWO), ASTM E698 and Coats-Redfern methods were used to calculate the activation energy of the samples from thermogravimetric data. The thermal stability of the iPP was improved by the introduction of the nanoparticles: the maximum decomposition temperature of the nanocomposite increased from 453 ºC to 457 ºC and the activation energy from 226 kJ/mol to 244 kJ/mol. The thermal degradation models of iPP can be described by “Contracting Sphere” model, whereas that to nanocomposite by Rn (n= 4.8) model (phase boundary reaction).
The Addition of Aluminum Nanoparticles to Polypropylene Increases Its Thermal...IJERA Editor
This work reports the thermal degradation kinetics of isotactic polypropylene (iPP) and iPP with incorporated Al nanoparticles. The Friedman, Flynn-Wall–Ozawa (FWO), ASTM E698 and Coats-Redfern methods were used to calculate the activation energy of the samples from thermogravimetric data. The thermal stability of the iPP was improved by the introduction of the nanoparticles: the maximum decomposition temperature of the nanocomposite increased from 453 ºC to 457 ºC and the activation energy from 226 kJ/mol to 244 kJ/mol. The thermal degradation models of iPP can be described by “Contracting Sphere” model, whereas that to nanocomposite by Rn (n= 4.8) model (phase boundary reaction).
Biomass is considered as a potential source of energy production.Gasification can be employed to convert
dilute biomass energy source in to gaseous products holding concentrated form of energy. A steady state model for fluidized
bed biomass gasifier is developed based on reaction kinetics and hydrodynamic aspects of fluidization. The presence of
sorbent for absorption of carbon dioxide from the product gas is also incorporated in the model.The developed model
predicts the variation of syngas composition, temperature, pressure and velocity along the height of gasifier. Experiments
were carried out in a lab scale fluidized bed biomass gasifier and the results were used to validate the model.An increase of
50.35% in H2 mole fraction and a decrease of 50.88 % in CO2 mole fraction were observed when CaO was used as the
sorbent.
Solvent Effect on the Enthalpy and Entropy of Activation for the Hydrolysis o...IJEACS
The rate of alkaline hydrolysis of ethyl cinnamate was measured over the temperature range of 20o C to 40 o C in water-acetone mixture at different composition 30 to 70% (v/v). The influence of solvent variation on reaction rate was examined in term of changes in the activation parameter. Depletion of H* and S* value with simultaneous increase in G* of the reaction in reaction media, reveals that the reaction is Enthalpy domination and Entropy controlled. The Iso- dielectric activation energy(ED) of reaction was found to decrease from 52.43 to 47.28 which is calculated by plotting log k values against different D. The Values of Iso-kinetic Temperature which is less than 300, clearly indicates that there is no appreciable interaction between solvent and solute present in the reaction media, i.e. reaction is not ion-dipole but ion-molecule type.
Linking Ab Initio-Calphad for the Assessment of the AluminiumLutetium SystemIRJESJOURNAL
Abstract: First-principles calculations within density functional theory (DFT) were used to investigate intermetallics in the Al-Lu system at 0 K. The five compounds of the system were investigated in their observed experimental structures. Thermodynamic modelling of the Au–Lu system was carried out by means of the CALPHAD (calculation of phase diagrams) method. The liquid phase and the intermetallic compounds Al3Lu, Al2Lu, AlLu, Al2Lu3 and AlLu2 are taken into consideration in this optimization. The substitutional solution model was used to describe the liquid phase. The five compounds are treated as stoichiometric phases. The enthalpies of formation of the compounds were found by the ab initio calculations and used in the optimization of the phase diagram.
THE PHASE RULE
phase rule
degree of freedom in mixture
one component system
two component system
pressure temperature diagram sulfur hydrogen
eutectic eutectoid mixture
Mechanism of the Reaction of Plasma Albumin with Formaldehyde in Ethanol - Wa...IOSR Journals
The Spectrophotometric determination of the acid dissociation/ionisation constant (pKa) of plasma albumin-formaldehyde adduct in both water solution and Ethanol solutions was carried out in this study. The pKa values obtained in both media were used to establish the Bronsted-linear type constants from plots of pKa against logarithm of second order rate constants obtained at varying pHs in the study. The result of the pKa values obtained in both water solution and ethanol-water mixtures were found to be in the range of 5.0 - 8.0. This pointed to the fact that only lysine residue with pKa value 8.3 that might have possibly reacted with formaldehyde in this reaction of all the known amino acid residues in plasma albumin. The corresponding Brønsted-type plots proportionality constants (β) for the reaction in water and ethanol-water mixtures were found to be β = 0.059 and 0.0057 respectively. The reaction mechanisms that have low values for proportionality constants α or β are considered to have a transition state closely resembling the reactant with little proton transfer (Cox et al, 1988). Thus, one would suggest that the cross-linking of formaldehyde with plasma albumin in water and ethanol-water mixtures proceeds through little proton transfer
Definition - Mechanism - Effect of dielectric constant on the rate of reactions in solutions - Salt effect - Primary salt effect - Bronsted – Bjerrum equation - Secondary salt effect - Effect of pressure on rate of reaction in solution - Volume of activation - Significance
inovaDay SC | Cetem | 26 de Setembro
Éverton Alvarenga
O Gastos Abertos é uma plataforma digital e educacional para esmiuçar os gastos públicos de modo que qualquer um possa entender como o governo gasta o nosso dinheiro. O projeto foi um dos finalistas do Desafio de Impacto Social do Google e recebeu uma doação de R$ 500 mil reais para sua implementação. A iniciativa ainda está na fase de concepção e a implementação está prevista para os próximos dois anos.
Biomass is considered as a potential source of energy production.Gasification can be employed to convert
dilute biomass energy source in to gaseous products holding concentrated form of energy. A steady state model for fluidized
bed biomass gasifier is developed based on reaction kinetics and hydrodynamic aspects of fluidization. The presence of
sorbent for absorption of carbon dioxide from the product gas is also incorporated in the model.The developed model
predicts the variation of syngas composition, temperature, pressure and velocity along the height of gasifier. Experiments
were carried out in a lab scale fluidized bed biomass gasifier and the results were used to validate the model.An increase of
50.35% in H2 mole fraction and a decrease of 50.88 % in CO2 mole fraction were observed when CaO was used as the
sorbent.
Solvent Effect on the Enthalpy and Entropy of Activation for the Hydrolysis o...IJEACS
The rate of alkaline hydrolysis of ethyl cinnamate was measured over the temperature range of 20o C to 40 o C in water-acetone mixture at different composition 30 to 70% (v/v). The influence of solvent variation on reaction rate was examined in term of changes in the activation parameter. Depletion of H* and S* value with simultaneous increase in G* of the reaction in reaction media, reveals that the reaction is Enthalpy domination and Entropy controlled. The Iso- dielectric activation energy(ED) of reaction was found to decrease from 52.43 to 47.28 which is calculated by plotting log k values against different D. The Values of Iso-kinetic Temperature which is less than 300, clearly indicates that there is no appreciable interaction between solvent and solute present in the reaction media, i.e. reaction is not ion-dipole but ion-molecule type.
Linking Ab Initio-Calphad for the Assessment of the AluminiumLutetium SystemIRJESJOURNAL
Abstract: First-principles calculations within density functional theory (DFT) were used to investigate intermetallics in the Al-Lu system at 0 K. The five compounds of the system were investigated in their observed experimental structures. Thermodynamic modelling of the Au–Lu system was carried out by means of the CALPHAD (calculation of phase diagrams) method. The liquid phase and the intermetallic compounds Al3Lu, Al2Lu, AlLu, Al2Lu3 and AlLu2 are taken into consideration in this optimization. The substitutional solution model was used to describe the liquid phase. The five compounds are treated as stoichiometric phases. The enthalpies of formation of the compounds were found by the ab initio calculations and used in the optimization of the phase diagram.
THE PHASE RULE
phase rule
degree of freedom in mixture
one component system
two component system
pressure temperature diagram sulfur hydrogen
eutectic eutectoid mixture
Mechanism of the Reaction of Plasma Albumin with Formaldehyde in Ethanol - Wa...IOSR Journals
The Spectrophotometric determination of the acid dissociation/ionisation constant (pKa) of plasma albumin-formaldehyde adduct in both water solution and Ethanol solutions was carried out in this study. The pKa values obtained in both media were used to establish the Bronsted-linear type constants from plots of pKa against logarithm of second order rate constants obtained at varying pHs in the study. The result of the pKa values obtained in both water solution and ethanol-water mixtures were found to be in the range of 5.0 - 8.0. This pointed to the fact that only lysine residue with pKa value 8.3 that might have possibly reacted with formaldehyde in this reaction of all the known amino acid residues in plasma albumin. The corresponding Brønsted-type plots proportionality constants (β) for the reaction in water and ethanol-water mixtures were found to be β = 0.059 and 0.0057 respectively. The reaction mechanisms that have low values for proportionality constants α or β are considered to have a transition state closely resembling the reactant with little proton transfer (Cox et al, 1988). Thus, one would suggest that the cross-linking of formaldehyde with plasma albumin in water and ethanol-water mixtures proceeds through little proton transfer
Definition - Mechanism - Effect of dielectric constant on the rate of reactions in solutions - Salt effect - Primary salt effect - Bronsted – Bjerrum equation - Secondary salt effect - Effect of pressure on rate of reaction in solution - Volume of activation - Significance
inovaDay SC | Cetem | 26 de Setembro
Éverton Alvarenga
O Gastos Abertos é uma plataforma digital e educacional para esmiuçar os gastos públicos de modo que qualquer um possa entender como o governo gasta o nosso dinheiro. O projeto foi um dos finalistas do Desafio de Impacto Social do Google e recebeu uma doação de R$ 500 mil reais para sua implementação. A iniciativa ainda está na fase de concepção e a implementação está prevista para os próximos dois anos.
Edição 158 do Diz Jornal, um jornal plural que aborda desde política, internet, direitos dos consumidores, cinema e saúde. Circula na cidade de Niterói.
Material de apoyo preparado por el grupo de Coordinadores de Capacitación, como tarea curricular dentro del curso de formación de Coordinadores; ciclo 2010. Anibal Carro https://orcid.org/0000-0003-0365-5638, et al.
Edital para o concurso do Ministério do Planejamento, Orçamento e Gestão para 150 vagas de Especialista em Políticas Públicas e Gestão Governamental (EPPGG).
Estude com as videoaulas do Concurso Virtual: www.concursovirtual.com.br
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Study of the Influence of Nickel Content and Reaction Temperature on Glycerol...IJRESJOURNAL
ABSTRACT: La2O3-SiO2-supported nickel catalysts were evaluated in glycerol steam reforming. The samples (30wt% La and 5, 10 and 15wt% of Ni on 70wt% commercial SiO2), prepared by the simultaneous impregnation method, were characterized by EDX, nitrogen physisorption, XRD, in-situ XRD, XANES and TPR. The analyses revealed NiO species weakly interact with the support and the different metallic surface areas of the catalysts. Catalytic tests were performed in a fixed bed reactor at 600oC and 15Ni catalyst, which showed the best performance, was also evaluated at 500oC and 700oC. According to the results, the Ni content on the catalyst surface interferes in the distribution of gaseous products H2, CO, CO2 and CH4. The increase in the Ni content increases the carbon formation during reaction. The reaction temperature affected the catalytic performance and the best results were obtained with the 15Ni catalyst at 600oC, which was also tested for 20 hours for the analysis of its stability.
Thermal regeneration of activated carbon saturated with nitrate ions from an ...IJAEMSJORNAL
The present study was initiated to help the simple and less expensive regeneration of activated carbons after saturation in rural area. In order to determine a regeneration time and the number of regeneration cycles, an adsorption test was necessary. Thus, 3h and 4 cycles of carbon regeneration are obtained after evaluation of the performance, percentage and adsorption capacity after each cycle. Regeneration percentages of 71.29, 54.05, 40.40, 28.06 % and 72.6, 69.84, 64.33, 34.98 %for respective concentrations of 30± 1.2 mg/L and 55 ± 1.6 mg/L are observed. Also, the performances of activated carbon 8.5, 10, 12, 20 g/L and capacities 24.04, 19.93, 14.9 and 10.35mg/g 35.7, 34.12, 31.43 and 17.09 mg/g respectively for dry season and rainy season were necessary to fix the number of cycles. The artisanal furnace with its ease of installation and its maximum temperature of 500±2°C is suitable for the regeneration of saturated activated carbon.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
This presentation speaks about competitive adsorption of CO2 and CH4 on coal. However, this project may be extended to any porous media on which competitive adsorption is to be observed.
A ruthenium-carbamato-complex derived from a siloxylated amine and carbon dio...Pawan Kumar
The rutheniumcarbamate complex derived from3-trimethoxysilyl-1-
propyl amine and carbon dioxidewas found to be a novel catalyst for
the oxidative cyanation of aromatic and cyclic tertiary amines to
corresponding a-amino nitriles in high to excellent yields by using
hydrogen peroxide and molecular oxygen as enviro-economic
oxidants. The developed protocol suggested an efficient alternative
for recycling carbon dioxide.
Solution Manual for Physical Chemistry – Robert AlbertyHenningEnoksen
https://www.book4me.xyz/solution-manual-physical-chemistry-alberty/
Solution Manual for Physical Chemistry - 6th Edition
Author(s) : Robert A. Alberty
This solution manual include all chapters of textbook (1 to 21).
HEAP SORT ILLUSTRATED WITH HEAPIFY, BUILD HEAP FOR DYNAMIC ARRAYS.
Heap sort is a comparison-based sorting technique based on Binary Heap data structure. It is similar to the selection sort where we first find the minimum element and place the minimum element at the beginning. Repeat the same process for the remaining elements.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
NUMERICAL SIMULATIONS OF HEAT AND MASS TRANSFER IN CONDENSING HEAT EXCHANGERS...ssuser7dcef0
Power plants release a large amount of water vapor into the
atmosphere through the stack. The flue gas can be a potential
source for obtaining much needed cooling water for a power
plant. If a power plant could recover and reuse a portion of this
moisture, it could reduce its total cooling water intake
requirement. One of the most practical way to recover water
from flue gas is to use a condensing heat exchanger. The power
plant could also recover latent heat due to condensation as well
as sensible heat due to lowering the flue gas exit temperature.
Additionally, harmful acids released from the stack can be
reduced in a condensing heat exchanger by acid condensation. reduced in a condensing heat exchanger by acid condensation.
Condensation of vapors in flue gas is a complicated
phenomenon since heat and mass transfer of water vapor and
various acids simultaneously occur in the presence of noncondensable
gases such as nitrogen and oxygen. Design of a
condenser depends on the knowledge and understanding of the
heat and mass transfer processes. A computer program for
numerical simulations of water (H2O) and sulfuric acid (H2SO4)
condensation in a flue gas condensing heat exchanger was
developed using MATLAB. Governing equations based on
mass and energy balances for the system were derived to
predict variables such as flue gas exit temperature, cooling
water outlet temperature, mole fraction and condensation rates
of water and sulfuric acid vapors. The equations were solved
using an iterative solution technique with calculations of heat
and mass transfer coefficients and physical properties.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
CW RADAR, FMCW RADAR, FMCW ALTIMETER, AND THEIR PARAMETERSveerababupersonal22
It consists of cw radar and fmcw radar ,range measurement,if amplifier and fmcw altimeterThe CW radar operates using continuous wave transmission, while the FMCW radar employs frequency-modulated continuous wave technology. Range measurement is a crucial aspect of radar systems, providing information about the distance to a target. The IF amplifier plays a key role in signal processing, amplifying intermediate frequency signals for further analysis. The FMCW altimeter utilizes frequency-modulated continuous wave technology to accurately measure altitude above a reference point.
2. Where α is the converted fraction, including devolatilization, Boudouard and reduction
reactions; k is the kinetic constant and t is the time reaction.
In the case of self-reducing pellets, the diffusion of the gases occurs inside to outside of the
pellet and the reactions take place within the agglomerates which leads to the control of the
reactions progresses commonly controlled by chemical and heat supply steps, and thus turns the
diffusion control irrelevant for the kinetic behavior. These phenomena ensure that the kinetic
behavior of the self-reducing pellets is essentially controlled by chemical reactions, where the
Boudouard reaction at lower temperatures plays the major role with heat transfer at higher
temperatures being the most important parameter to be controlled [3].
Materials and Methods
In this work kinetic runs in TGA-DSC Q600 were carried out to analyze the kinetic behavior
of self-reducing mixtures. Some important kinetic parameters were obtained such as kinetic
constant temperature dependence and apparent activation energy.
Self-reducing mixtures production
The compositions of the mixtures were based on the carbon percentage according to the
Table 1.
Table 1. Composition of the self-reducing mixtures.
Mixtures % Pellet Feed % BOF dust % Biomass
Mixture 1 36.5 47.7 15.8
Mixture 2 32.1 47.1 20.8
Mixture 3 27.9 41.0 31.1
The percentage values of the mixtures described in the Table 1were based on the carbon
content in the biomass (56.2% of fixed carbon).
In addition, a special attention was paid to the zinc oxide percentage present in the mixtures
due to well-known deleterious effects on the conventional reduction processes. In this work the
maximum zinc oxide was kept lower than 2.9% which limited the amount BOF slag in the mixtures.
Kinetic runs of the self-reducing mixtures
The mass changes during the experiment were recorded using TGA-DSC Q600 equipment
as can be seen in Fig. 1. Some parameters used in the experiments were: heating rate 5ºC/min, until
to achieve the temperatures 900, 950, 1000, 1050 and 1100ºC and keeping at this temperature for 60
minutes (except for 1100ºC, the experiment took around 5 hours in this temperature to ensure that
all carbon present in the sample is reacted). In addition, the atmosphere used was nitrogen with a
flow constant of 100ml/min.
(a) (b)
Fig. 1. (a) Inner furnace of the equipment; (b) TGA-DSC used for kinetic runs.
1008 21st Brazilian Conference on Materials Science and Engineering
3. Kinetic Parameters Estimation
The reacted fraction was calculated applying the Eq. 7.
(7)
Where mo is the initial mass, mt is the mass changing with the time and mf is the final mass
in the higher temperature, in this case, 1100ºC. The diagrams for the three different concentrations
were divided in regions according to the reactions that occur during the time. Applying Equation 6,
it was obtained the kinetic constant for the different regions; and using these results the activation
energy was predicted according to Eq. 8.
(8)
The regions were defined according to the change of the inclination of the curve in the
diagram α x t, showed in the Table 2.
Table 2. Different regions where the reactions occur.
Regions Definition Temperature range
1 Humidity Until 300ºC
2 Devolatilization 300ºC < T < 380ºC
3 Boudouard and Reduction Fe2O3 → Fe3O4 650ºC < T < 750ºC
4 Reduction Fe3O4 → FeO 800ºC < T < 880ºC
5 Reduction FeO → Fe 880ºC < T < until the end
Results and Discussion
Results of TGA-DSC experiments
The results are presented taking the derivative values of the converted fractions and the heat
flows during the runs.
(a) (b)
Materials Science Forum Vol. 869 1009
4. (c) (d)
(e) (f)
Fig. 2. (a), (c) and (e): derivative of α for 15, 20 and 30% of carbon present in the mixtures,
respectively. (b), (d) and (f): heat flow curves for 15, 20 and 30% of carbon present in the mixtures,
respectively.
The Fig. 2 (a to f) are the results of the derivative of α versus time and heat flow versus time
for the three mixtures with different carbon content. The peaks that appear in the diagrams obtained
for (dα/dt) versus time represent the weight change that occurs when different reactions happen,
described in Table 2. For all mixtures (15, 20 and 30% of carbon), it was possible to observe the
highest degree of conversion occurred at 1100 ° C, since the endothermic character of the reactions;
whereas for 1000 and 1050ºC with 30% of carbon, the reduction process was completed around
300min, with a maximum peak around 200 min test, that probably represents the reaction
mechanism FeO → Fe. For the results for the mixture containing 15% of carbon at 1050ºC it is
possible to visualize a peak around to 200 min of run which is smaller than the previous peak, and
this fact does not occur for 20 and 30% of carbon. This guarantees that for 20 and 30% of carbon
the reaction was completed since for the mixture containing 15% of carbon is not allowing the
amount of carbon to complete the reduction. For lower temperatures and for all concentrations the
converted fraction was lower compared to higher temperatures. In addition, the first peak that
appears around the 50 min of run occurs between the temperature values of 350 to 400o
C and this
was corroborated by an experiment performed in previous research [5] that is consistent with the
kinetic analysis of elephant grass biomass using TGA-DSC. Analyzing the heat flow diagrams in
Figures 2 (b), (d) and (f) it is possible to observe the inflections along the curve in the same time
intervals where the peaks of dα/dt. occur These inflections represent the endothermic reactions and
the heat flux is negative due to the output of energy of the furnace to the sample.
1010 21st Brazilian Conference on Materials Science and Engineering
5. Results of kinetic parameters
Applying the kinetic law of order first, described in Equation 6, to the different regions
defined in this study it was possible to find the kinetic constant, k, for the reactions corresponding
to the different regions. Tab. 3 shows the results of the kinetic constants for each region defined, for
the three concentrations, being that for regions 1, 2 and 3, it was displayed the average constant,
since all the peaks for these regions were obtained in the same temperature, due to the heating rate
has been constant.
Table 3. Kinetic constants for regions 1, 2 and 3 for the different concentrations of carbon.
Concentration Regions Kinetic constant(s-1
)
1 0.00082
15% 2 0.00098
3 0.0066
1 0.00088
20% 2 0.00094
3 0.00638
1 0.00086
30% 2 0.00112
3 0.00756
The bigger constant was for the sample containing 30% of carbon for the mechanism Fe2O3
→Fe3O4 (region 3), since a bigger fraction of hematite is reacted.
For 4 and 5 regions the kinetic constant values were increasing according to the increase of
temperature. Applying Equation 8, the activation energy was predicted for these regions. The results
are displayed in the Tab. 4. The bigger kinetic constants obtained for the 4 and 5 regions were
respectively, 0.00237 e 0.0258 s-1
for 1100 o
C temperature to the 30% of carbon samples.
According to the studies performed previously [6], many authors have determined the activation
energy using Arrhenius law and the values reported are between 40KJ/mol and 418KJ/mol.
Table 4. Apparent activation energy for different samples of 4 and 5 regions.
Carbon Regions Apparent Activation Energy (J/mol)
15% 5801.84
20% 4 9601.84
30% 12727.07
15% 84578.32
20% 5 142011.42
30% 178327.00
The lowest apparent activation energy values were for mixtures containing 15% of carbon,
since this composition is not enough to complete the reaction.
Conclusions
• In this work it was verified that the self-reducing mixtures containing biomass elephant
grass, iron ore and dust LD follows the first order kinetic law.
• The difference of kinetic behavior for samples containing, 20 and 30% of carbon was
negligible, and then, it is advantageous use the mixture with less fuel.
• When the activation energy values obtained for the reactions of Fe3O4 → FeO and FeO →
Fe are compared with values of global activation energy for self-reducing agglomerates
reported in the literature, the values obtained in this work were relatively lower, due to the
high reactivity of the biomass requiring a smaller energy demand.
• Applying the biomass as a carbonaceous source for self-reducing pellets requires a further
studies. However, according with these preliminary results, it is clear the kinetic advantages
of the mixtures with biomasses of elephant grass compared with fossil fuels.
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6. References
[1] F.F. Grillo, J.A.S. Tenório, J.R Oliveira: Rev. Esc. Minas Vol. 66 (2013), p. 301.
[2] J.C. D’abreu, K.M. Martins, J.H. Noldin Junior, The iron morphology of self-reducing
briquettes. In: Brazil-Japan Symposium on dust processing-energy-environment in
metallurgical industries, 4, 2002, Sao Paulo. Proceedings…São Paulo: EPUSP 89-102.
[3] M.B. Mourão, C. Takano: Mineral Processing and Extractive Metallurgy Review: An
International Journal Vol. 24 (2002), p.183.
[4] A. Bonalde, A. Henriquez, M. Manrique: ISIJ International Vol. 45 (2005), p. 1255.
[5] V. Strezov, T.J. Evans, C. Hayman: Bioresource Technology Vol. 99 (2008), p. 8394.
[6] M.B. Mourão, R.C. Nascimento, C. Takano: Canadian Metallurgical Quarterly Vol. 45 (2006),
p. 161.
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