Mechanism and Kinetics of Pyrolysis of Coal With High Ash and Low Fixed Carbon Contents

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Lin Yang ◽  
Jing-yu Ran ◽  
Li Zhang
Keyword(s):  
Activation Energy ◽  
High Efficiency ◽  
Diffusion Mechanism ◽  
Volatile Matter ◽  
Global Symmetry ◽  
Pyrolysis Process ◽  
Heating Rates ◽  
Characteristic Index ◽  
Pyrolysis Reaction ◽  
Second Stage

There are much coal with low content of volatile matter (Vad < 20%), high content of ash (Aad > 50%), low heating caloric (∼10,000 kJ/kg) in China. It is very important to study pyrolysis performance of the coal to ensure high efficiency of utilization and low pollution emissions. In this paper, we study the pyrolysis reaction details of different types of this coal from different regions of China under different pyrolysis pressures, temperatures, particle sizes, and heating rates by thermo-gravimetry (TG) method. The pyrolysis characteristic temperatures and the characteristic index of volatilization matter released of coal gangue (CG) are obtained in this work. In addition, the detailed process of mechanism and kinetic parameters of pyrolysis are presented. The results show that many factors have an obvious influence on the pyrolysis reaction of the coal. The pyrolysis process of the coal is comprised of two stages. At the primary stage(t < 560 °C), the pyrolysis reaction is dominated by the diffusion rate of volatile matter because of the high ash content, which is the global symmetry diffusion mechanism, and the volatile matter of this stage is more difficult to come out and a high pyrolysis activation energy is observed. With increasing pyrolysis temperature, the pyrolysis reaction is moving into diffusion limitation, the volatile matter is released plentifully, and the low activation energy is found. At the second stage (t > 560 °C), the pyrolysis reaction is governed by the tar-released reaction and the pyrolysis reaction order is 1.5. The high activation energy is also observed for the second stage pyrolysis process.

scholarly journals The Reduction Behavior of Ocean Manganese Nodules by Pyrolysis Technology Using Sawdust as the Reductant

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 850 ◽  
Author(s):  
Xiang-yi Deng ◽  
Dong-sheng He ◽  
Ru-an Chi ◽  
Chun-qiao Xiao ◽  
Jin-gang Hu
Keyword(s):  
Activation Energy ◽  
High Efficiency ◽  
Acid Leaching ◽  
Reduction Process ◽  
Reduction Reaction ◽  
Pyrolysis Process ◽  
Manganese Nodules ◽  
Valuable Metals ◽  
Shrinking Core ◽  
Isothermal Kinetic

Ocean manganese nodules, which contain abundant Cu, Co, Ni and Mn resources, were reduced using biomass (sawdust) pyrolysis technology. Valuable metals were further extracted by acid leaching after the reduction process with high efficiency. The effects of sawdust dosage, reduction temperature, and time were investigated to obtain optimal operating parameters. The extraction rates of Mn, Cu, Co, and Ni reached as high as 96.1%, 91.7%, 92.5%, and 94.4%, respectively. Results from TGA show that the main pyrolysis process of sawdust occurs at temperature range of 250–375 °C with a mass loss of 59%, releasing a large amount of volatile substances to reduce the ocean manganese nodules. The pyrolysis activation energy of sawdust was calculated to be 52.68 kJ∙mol−1 by the non-isothermal kinetic model. Additionally, the main reduction reaction behind the main sawdust pyrolysis process was identified by the comparison of the assumed and actual TG curve. The thermodynamic analysis showed that the high valence manganese minerals were gradually reduced to Mn2O3, Mn3O4, and MnO by CO generated from sawdust pyrolysis. The shrinking core model showed that the reduction process is controlled by the surface chemical reaction with activation energy of 45.5 kJ∙mol−1. The surface of reduced ore and acid leached residue exhibited a structure composed of relatively finer pores and rougher morphology than the raw ore.

Kinetic Study of PVC Pyrolysis in Air by Thermogravimetric Analysis Using the Friedman Method

2012 ◽  
Vol 427 ◽  
pp. 64-69 ◽  
Author(s):  
Bin Han ◽  
Yu Long Wu ◽  
Wei Feng ◽  
Zhen Chen ◽  
Ming De Yang
Keyword(s):  
Activation Energy ◽  
Thermogravimetric Analysis ◽  
Thermal Degradation ◽  
Heating Rate ◽  
Inert Atmosphere ◽  
Nitrogen Atmosphere ◽  
Pyrolysis Process ◽  
Pyrolysis Mechanism ◽  
Second Stage ◽  
Friedman Method

The thermal degradation of PVC in air ambience was investigated by the thermogravimetric analysis (TGA). The experiments were carried out at different heating rate of 5, 10, 20 and 40°C/min, respectively. The activation energy was calculated by the Friedman method. The pyrolysis mechanism of PVC in air was discussed and compared with that in Nitrogen atmosphere. The pyrolysis process of PVC in air could be divided into two main stages: 200 °C ~ 380 °C and 400 °C ~ 600 °C, which obtained by TGA at the heating rate of 5°C/min. The second stage could be further subdivided into two parts by 465 °C. It can be concluded that the oxygen in air affected the second stage more obviously than that of the first one, in comparison with inert atmosphere. The activation energy of the second stage was still larger than the first stage.

scholarly journals Comprehensive Kinetic Study of Pyrolysis of Sunan Candlenut: The Effect of Using Iron Oxide, Zeolite and ZSM-5 as Bed Materials

2021 ◽  
Vol 39 (2) ◽  
pp. 493-502
Author(s):  
I Made Rajendra ◽  
I Nyoman Suprapta Winaya ◽  
Ainul Ghurri ◽  
I Ketut Gede Wirawan
Keyword(s):  
Activation Energy ◽  
Iron Oxide ◽  
Fixed Bed ◽  
Calorific Value ◽  
Volatile Content ◽  
Pyrolysis Process ◽  
Heating Rates ◽  
Calculation Results ◽  
Bed Materials ◽  
Bed Material

The purpose of bed material in the pyrolysis process is to reduce the need for heat energy. In this study, three kinds of sands were observed as bed material, namely iron oxide, zeolite, and ZSM-5 in the slow fixed bed pyrolysis of sunan candlenut oilcake (SCO). To evaluate the activation energy, pyrolytic kinetics were carried out using the iso-conversional method with the KAS, OFW, and Friedman models. They involved calculating the data from the thermogravimetric analysis (TGA) test at heating rates of 5, 10, 20 and 40 K/min. Furthermore, the results showed that SCO had a high volatile content of 82.80%, alongside a calorific value of 26.93 MJ/kg. The calculation results showed that the activation energy of SCO was 169.140 kJ/mol which decreased 1.45% in the KAS model, and 1.92% in the OFW model with the addition of ZSM-5 bed material. Therefore, the use of ZSM-5 bed material in the pyrolysis process reduces the activation energy.

Study on Volatile Evolution during the Eucalyptus Pyrolysis by Using TG-FTIR Analysis

2014 ◽  
Vol 884-885 ◽  
pp. 148-153
Author(s):  
Dian Zheng Fu ◽  
Ye Tang ◽  
Zheng Hui Fu ◽  
Hong Liang Zhang ◽  
Wei Li
Keyword(s):  
Fourier Transform ◽  
Thermogravimetric Analysis ◽  
South China ◽  
Volatile Matter ◽  
Infrared Analysis ◽  
Ftir Analysis ◽  
Pyrolysis Process ◽  
Heating Rates ◽  
Pyrolysis Products ◽  
Decomposition Stage

In this study, thermogravimetric analysis coupled with Fourier transform infrared analysis (TG-FTIR) was used to studying the volatile evolution characteristic during the eucalyptus pyrolysis from South China. The thermogravimetric analysis results indicate that the pyrolysis of eucalyptus occurred in three main stages which are the moisture vaporization stage, the volatile matter release stage and the char decomposition stage. The major gases evolved during the pyrolysis process were identified to be H2O, CO, CO2, CH4. In addition, the effects of different heating rates on the emissions of these pyrolysis products have been studied.

scholarly journals Decomposition Characteristics and Kinetics of Microalgae in N2 and CO2 Atmospheres by a Thermogravimetry

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Xu Qing ◽  
Ma Xiaoqian ◽  
Yu Zhaosheng ◽  
Cai Zilin ◽  
Ling Changming
Keyword(s):  
Activation Energy ◽  
Thermogravimetric Analysis ◽  
Thermal Degradation ◽  
Apparent Activation Energy ◽  
Kinetic Parameters ◽  
Reaction Order ◽  
Heating Rates ◽  
Residual Mass ◽  
Second Stage ◽  
Kinetics Of

The thermal degradation characteristics of microalgae were investigated in highly purified N2 and CO2 atmospheres by a thermogravimetric analysis (TGA) under different heating rates (10, 20, and 40°C/min). The results indicated that the total residual mass in CO2 atmosphere (16.86%) was less than in N2 atmosphere (23.12%); in addition, the kinetics of microalgae in N2 and CO2 atmospheres could be described by the pseudo bicomponent separated state model (PBSM) and pseudo-multi-component overall model (PMOM), respectively. The kinetic parameters calculated by Coats-Redfern method showed that, in CO2 atmosphere, the apparent activation energy (E) of microalgae was between 9.863 and 309.381 kJ mol−1 and the reaction order (n) was varied from 1.1 to 7. The kinetic parameters (E,n) of the second stage in CO2 atmosphere were quite similar to those in N2 atmosphere.

scholarly journals Co-Combustion Studies of Low-Rank Coal and Refuse-Derived Fuel: Performance and Reaction Kinetics

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3796
Author(s):  
Mudassar Azam ◽  
Asma Ashraf ◽  
Saman Setoodeh Setoodeh Jahromy ◽  
Sajjad Miran ◽  
Nadeem Raza ◽  
...  
Keyword(s):  
Activation Energy ◽  
Waste Management ◽  
Energy Demand ◽  
Power Plants ◽  
Combustion Process ◽  
Isoconversional Methods ◽  
Low Rank ◽  
Heating Rates ◽  
Average Activation Energy ◽  
Refuse Derived Fuel

In connection to present energy demand and waste management crisis in Pakistan, refuse-derived fuel (RDF) is gaining importance as a potential co-fuel for existing coal fired power plants. This research focuses on the co-combustion of low-quality local coal with RDF as a mean to reduce environmental issues in terms of waste management strategy. The combustion characteristics and kinetics of coal, RDF, and their blends were experimentally investigated in a micro-thermal gravimetric analyzer at four heating rates of 10, 20, 30, and 40 °C/min to ramp the temperature from 25 to 1000 °C. The mass percentages of RDF in the coal blends were 10%, 20%, 30%, and 40%, respectively. The results show that as the RDF in blends increases, the reactivity of the blends increases, resulting in lower ignition temperatures and a shift in peak and burnout temperatures to a lower temperature zone. This indicates that there was certain interaction during the combustion process of coal and RDF. The activation energies of the samples were calculated using kinetic analysis based on Kissinger–Akahira–Sunnose (KAS) and Flynn–Wall–Ozawa (FWO), isoconversional methods. Both of the methods have produced closer results with average activation energy between 95–121 kJ/mol. With a 30% refuse-derived fuel proportion, the average activation energy of blends hit a minimum value of 95 kJ/mol by KAS method and 103 kJ/mol by FWO method.

Thermo-catalytic decomposition of polystyrene waste: Comparative analysis using different kinetic models

2019 ◽  
Vol 38 (2) ◽  
pp. 202-212 ◽  
Author(s):  
Ghulam Ali ◽  
Jan Nisar ◽  
Munawar Iqbal ◽  
Afzal Shah ◽  
Mazhar Abbas ◽  
...  
Keyword(s):  
Activation Energy ◽  
Copper Oxide ◽  
Solid Waste ◽  
Thermodynamic Parameters ◽  
Model Fitting ◽  
Catalytic Decomposition ◽  
Decomposition Reaction ◽  
Inert Atmosphere ◽  
Heating Rates ◽  
Model Free

Due to a huge increase in polymer production, a tremendous increase in municipal solid waste is observed. Every year the existing landfills for disposal of waste polymers decrease and the effective recycling techniques for waste polymers are getting more and more important. In this work pyrolysis of waste polystyrene was performed in the presence of a laboratory synthesized copper oxide. The samples were pyrolyzed at different heating rates that is, 5°Cmin−1, 10°Cmin−1, 15°Cmin−1 and 20°Cmin−1 in a thermogravimetric analyzer in inert atmosphere using nitrogen. Thermogravimetric data were interpreted using various model fitting (Coats–Redfern) and model free methods (Ozawa–Flynn–Wall, Kissinger–Akahira–Sunose and Friedman). Thermodynamic parameters for the reaction were also determined. The activation energy calculated applying Coats–Redfern, Ozawa–Flynn–Wall, Kissinger–Akahira–Sunose and Friedman models were found in the ranges 105–148.48 kJmol−1, 99.41–140.52 kJmol−1, 103.67–149.15 kJmol−1 and 99.93–141.25 kJmol−1, respectively. The lowest activation energy for polystyrene degradation in the presence of copper oxide indicates the suitability of catalyst for the decomposition reaction to take place at lower temperature. Moreover, the obtained kinetics and thermodynamic parameters would be very helpful in determining the reaction mechanism of the solid waste in a real system.

Magnetic Properties, Nanostructure, and Ordering Kinetics of Nb Additive FePtCu Films

2010 ◽  
Vol 638-642 ◽  
pp. 1743-1748
Author(s):  
G.J. Chen ◽  
Y.H. Shih ◽  
Jason S.C. Jang ◽  
S.R. Jian ◽  
P.H. Tsai ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Activation Energy ◽  
Magnetic Properties ◽  
Heating Rates ◽  
Fept Alloy ◽  
Ordering Kinetics ◽  
Nb Content ◽  
Kinetics Of ◽  
Nb Addition ◽  
Microstructure And Magnetic Properties

In this study,the (FePt)94-xCu6Nbx (x=0, 2.87, 4.52, 5.67) alloy films were prepared by co-sputtering. The effects of Nb addition content and heat treatment on the microstructure and magnetic properties of the polycrystalline FePtCu films are reported. Our previous experiments showed that the ordering temperature of the (FePt)94Cu6 films reduced to 320 °C, which is much lower than that of the FePt alloy. However, the grain growth after heat treatment limited the practical application in recording media. By adding the Nb content in the (FePt)94Cu6 film, the grain sizes of the films can be adjusted from 50 to 18nm, even for the films annealed at temperature as high as 600°C. DSC traces of as-deposited disorder films at different heating rates, to evaluate the crystallization of the order phase, revealed that the addition of Nb enhanced the activation energy of ordering from 87 kJ/mol to 288 kJ/mol for the (FePt)94-xCu6Nbx (x=0 and 2.87, respectively) films. The reduction of the grain size and the corresponding increase in the activation energy of the Fe-Pt-Cu-Nb films might result from the precipitation of the Nb atoms around the ordering FePt phase. The (FePt)94-xCu6Nbx (x=2.87) film showed a coercive force of 13.4 kOe and the magnetization of 687 emu/cc.

scholarly journals Superior Degradation Performance of Nanoporous Copper Catalysts on Methyl Orange

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 913
Author(s):  
Jinyi Wang ◽  
Sen Yang
Keyword(s):  
Activation Energy ◽  
Methyl Orange ◽  
High Efficiency ◽  
Low Cost ◽  
Degradation Process ◽  
Copper Catalysts ◽  
Reaction Rate Constant ◽  
Nanoporous Structure ◽  
Intra Particle Diffusion ◽  
Different Temperatures

The development of low-cost and high-efficiency catalysts for wastewater treatment is of great significance. Herein, nanoporous Cu/Cu2O catalysts were synthesized from MnCu, MnCuNi, and MnCuAl with similar ligament size through one-step dealloying. Meanwhile, the comparisons of three catalysts in performing methyl orange degradation were investigated. One of the catalysts possessed a degradation efficiency as high as 7.67 mg·g−1·min−1. With good linear fitting by the pseudo-first-order model, the reaction rate constant was evaluated. In order to better understand the degradation process, the adsorption behavior was considered, and it was divided into three stages based on the intra-particle diffusion model. Three different temperatures were applied to explore the activation energy of the degradation. As a photocatalytic agent, the nanoporous structure of Cu/Cu2O possessed a large surface area and it also had low activation energy, which were beneficial to the excellent degradation performance.

scholarly journals Analysis and classification of tem¬perature measurements during melting and casting of alloys using neural networks

2020 ◽  
Vol 63 (10) ◽  
pp. 856-861
Author(s):  
A. V. Fedosov ◽  
G. V. Chumachenko
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Human Factor ◽  
High Efficiency ◽  
Thermal Conditions ◽  
Second Stage ◽  
Three Stages ◽  
Fully Automatic ◽  
Artificial Neural

The article considers the issues of monitoring the thermal conditions of alloys melting and casting at foundries. It is noted that the least reliable method is when the measurement and fixing the temperature is assigned to the worker. On the other hand, a fully automatic approach is not always available for small foundries. In this regard, the expediency of using an automated approach is shown, in which the measurement is assigned to the worker, and the values are recorded automatically. This method assumes implementation of an algorithm for automatic classification of temperature measurements based on an end-to-end array of data obtained in the production stream. The solving of this task is divided into three stages. Preparing of raw data for classification process is provided on the first stage. On the second stage, the task of measurement classification is solved by using neural network principles. Analysis of the results of the artificial neural network has shown its high efficiency and degree of their correspondence with the actual situation on the work site. It was also noted that the application of artificial neural networks principles makes the classification process flexible, due to the ability to easily supplement the process with new parameters and neurons. The final stage is analysis of the obtained results. Correctly performed data classification provides an opportunity not only to assess compliance with technological discipline at the site, but also to improve the process of identifying the causes of casting defects. Application of the proposed approach allows us to reduce the influence of human factor in the analysis of thermal conditions of alloys melting and casting with minimal costs for melting monitoring.

Sign in / Sign up

Export Citation Format

Share Document